Search

This study evaluated the effects of planning methods—pushing and pulling—on the surface topographic characteristics of Cedrela sinensis and Korean Paulownia wood boards according to ISO 25178 standards. Surface roughness was assessed using a stylus profilometer (Mitutoyo SJ301) and a 3D Optical Profilometer (VR-6000, Keyence). The parameters measured included arithmetical mean height (Ra and Sa), root mean square roughness (Rq), average maximum height of the surface (Rz and Sz), texture aspect ratio (Str), the spatial parameter of the surface (Spc), and developed interfacial area ratio (Sdr). These parameters collectively provide a comprehensive description of a surface's texture, aiding in assessing its roughness, directionality, and functional characteristics. On average, Cedrela sinensis push-finished surfaces showed Ra of 16.78 μm, while pull-finished surfaces showed Ra of 11.22 μm. For Paulownia, push-finished surfaces had Ra of 6.04 μm, while pull-finished surfaces had Ra of 5.83 μm. Statistical t-test results showed no significant differences between push and pull planning methods (p > 0.05). The surface roughness analysis reveals that Cedrela sinensis surfaces exhibit higher roughness, more significant height variations, and more complex textures than Paulownia. These findings are valuable for the woodworking industry, offering insights into optimizing planning methods for specific wood species and applications. [ABSTRACT FROM AUTHOR]

As a typical 3D printing process, fused filament fabrication still has disadvantages when operating on manufacturing lines due to the non-uniform textures of the oriented surfaces of the 3D-printed components. This work investigates the effects of structural parameters, i.e., orientations angle, ABS and PLA materials, three different layer thicknesses, three different perimeters, and three different infill rates utilizing a balanced modified Taguchi experimental design and 63 different parametric combinations to characterize the surface roughness parameters: average Ra, mean roughness depth Rz, root mean square Rq, skewness Rsk, and kurtosis Rku. The analysis of the experimental results, i.e., the levels mean values analysis plots and linear residual analysis of variances, showed that the layer thickness strongly influences all surface parameters and interacts considerably with all orientations. In contrast, material type, number of perimeters, and infill rate had insignificant impacts on surface roughness parameters. Finally, the additive linear modelling approach was utilized and validated for proper predictions, making it helpful for surface engineering applications. [ABSTRACT FROM AUTHOR]

In this paper, a novel double-disc straight groove lapping (DDSGL) method is proposed to reduce roundness error and improve surface roughness of tapered rollers. According to the conjugate surface principle and the kinematic characteristics of the tapered roller, the theoretical contour of the grinding tool working surface was designed. The contact relationship between the rollers and the working surface of the grinding tool is established. The relative motion between the tapered rollers and the grinding tool is discussed in detail, and the lapping trajectory on the rolling surface of tapered rollers is calculated and analyzed. The impact of the system's structural parameters (i.e., eccentric circular groove radius, eccentricity, and upper disc circular groove radius) as well as the kinematic parameters (lower disc rotational speed) on the uniformity of the lapping trajectory in the lapping process was explored. The structural parameters of the DDSGL equipment were determined using the standard deviation of the lapping trajectory distributed on the tapered roller rolling surface. Finally, the lapping experiments of tapered rollers were carried out in a homemade equipment, and the results show that the newly proposed method can effectively improve the roundness and reduce the surface roughness of the tapered rollers. [ABSTRACT FROM AUTHOR]

Ultrasonic rolling extrusion process (UREP) is the newly arisen surface strengthening technology, which can effectively reduce the surface roughness of the workpiece and improve the residual compressive stress at the certain depth on the surface so that it has great adaptability to the enhancement of the surface properties of the bearing ring. Through theoretical analysis, finite element simulation, and experiment method, the surface mechanical properties and the surface roughness of UREP strengthening when applied to the material of the wind power bearing ring are studied. Firstly, the strengthening principle of UREP is illustrated. Secondly, according to the motion trajectory of the rolling ball during UREP, the kinematic model of UREP is established. The forming principle of the surface micromorphology during UREP is explored. Thirdly, based on the contact characteristics between the rolling ball and the surface of the workpiece, the contact mechanics model of UREP is established. Based on Hertz contact theory, elastoplastic mechanics theory, and contact mechanics theory, the mechanical properties of the contact area between the rolling ball and the surface of the workpiece during UREP are analyzed. Finally, the simulation and experiment of 42CrMo steel cylindrical workpiece during UREP are carried out, and the variation trends in the simulation values are found to be consistent with those observed in the experimental results. The results show that the residual compressive stress generated in the surface of 42CrMo cylindrical workpiece after UREP gradually increases with the increase of the layer depth and then decreases and transforms into the residual tensile stress. Moreover, the surface roughness first decreases and then increases with the rise of the amplitude and the static pressure. Similarly, it gradually improves when the feed rate and rotational speed rises. The established UREP simulation is useful for imitating the actual machining process of 42CrMo steel during UREP, which extends the effective way for UREP parameter optimization. [ABSTRACT FROM AUTHOR]

The Ti-6Al-4V alloy is an important material used in many high-end devices, such as medical, aerospace, petrochemical, and sports equipment. Thus, the feasibility of producing Ti-6Al-4V with mirror surface quality through magnetic polishing was assessed in this study. One of the extremely challenging aspects of magnetic polishing for Ti-6Al-4V alloys is the generation of a magnetic field suitable for surface-quality finishing. Moreover, machined material residue cannot be completely removed, the alloy has limited application, and uniform surface quality on a large workpiece surface cannot be achieved because generating strong and suitable magnetic field is currently infeasible. To create a polishing process with a highly efficient magnetic field source for improving material removal rate and surface quality, a linear variable magnetic field array was proposed by Halbach. Finite element simulation processes combined with experimental validation provide an efficient polishing model with high field area and intensity generated by an improved Halbach magnet array. The magnetic force generated by the improved Halbach array and the force distribution process on the Fe3O4 magnetic particle were analyzed. Thus, material removal and the distribution and pressure of abrasive SiO2 particles acting on the polished surface were examined. The influences of technological factors on surface quality and material removal ability were systematically studied. The proposed chemical–magnetorheological finishing model showed a considerably increased magnetic field generation compared with the previous model (1.7 times that of the conventional Halbach array), thereby efficiently removing materials. Polishing models established for Ti-6Al-4V alloy markedly improved surface quality after 80 min of treatment, and an ultrafine workpiece surface showed an Ra of 1 nm, which had an initial roughness of approximately 500 nm. [ABSTRACT FROM AUTHOR]

This research studied the effect of rice husk ash (RHA) during the turning of AlSi10Mg aluminum alloy. Stir casting was the chosen fabrication technique for this investigation. The combined effects of the following turning process parameters including cutting speed (s), feed (f), depth of cut (d), and weight fraction of reinforcement ( w t ) on the responses; that is the tool wear and surface roughness were studied. Taguchi L 16 orthogonal array was adopted to determine the experimental runs. The analysis of variance (ANOVA) for the tool wear and the surface roughness showed that the feed and the cutting speed were the most significant factors influencing the tool wear and surface roughness, respectively. Using single objective optimization also affirmed the feed and cutting speed as the most influencing parameters for the tool wear and surface roughness, respectively. The predicted model for tool wear and surface roughness obtained from the regression equation shows a good correlation with the experimental results. A correlation of 95% and 94% of tool wear and surface roughness was determined between the predicted and corresponding experimental results. [ABSTRACT FROM AUTHOR]

The present research aims to improve the surface quality of laser powder bed fusion (LPBF) built cobalt chrome alloy (CoCr) by pulse laser remelting. The laser power, overlap percentage, and spot diameter are varied to determine the best parameters for laser polishing. The microhardness and microstructural changes associated with pulse laser remelting are described. Surface morphology and surface roughness parameters are reported for various laser remelting parameters. Among the three different spot diameters, 1, 2, and 3 mm, the maximum (> 50%) reduction in surface roughness was obtained for 2 mm with 1J laser energy and 50% X and 20% Y as well as 20% X and 50% Y overlaps. A DoE- and RSM-based approach has been utilized for parametric optimization of the surface roughness. The squared laser power is identified as a critical parameter by ANOVA. A Pareto chart confirms the significance of squared laser power across spot diameters. Optimization suggests that a 2-mm spot diameter works best with specific parameters to produce a better surface finish. However, the nanosecond order laser pulses have a limitation on the depth of surface modification without severe ablation and thereby on the reduction in the surface roughness. [ABSTRACT FROM AUTHOR]

Gray cast iron (GCI) brake rotors are prone to corrosion, particularly in electric vehicles (EVs), owing to their regenerative braking systems. Ferritic nitrocarburizing (FNC) heat treatment has been used to improve the corrosion resistance and cleanability of GCI rotors. However, pre-existing residual stresses in the rotors can lead to distortion after FNC processing, thereby affecting the functional and tolerance requirements. This study investigated the effects of stress-relief (SR) heat treatment and natural aging (NA) on the natural frequency, damping properties, surface roughness, and geometric tolerances of GCI brake rotors before and after FNC treatment. The GCI brake rotors were subjected to SR and NA processes, followed by FNC treatment. The natural frequency, damping Q-factor, surface roughness, and geometric tolerances were measured and analyzed using two-way ANOVA at a 95% confidence level (α = 0.05). The results showed that SR heat treatment significantly reduced the effect of residual stresses and improved geometric tolerances compared to NA. The FNC treatment increased the surface roughness and slightly improved the damping properties but had an insignificant effect on the natural frequency. The combination of SR and FNC treatments provided the best overall performance in terms of quality, geometric tolerance, and surface finish. This study highlights the importance of SR heat treatment for optimizing the manufacturing process of FNC-treated GCI brake rotors for EVs. [ABSTRACT FROM AUTHOR]

Through Silicon Via (TSV), a kind of 3D packaging technique, can improve chip integration based on "More than Moore" scheme. The larger copper area ratio at the TSV barrier layer interface requires strong adjustability of the removal rate selection ratio of copper, tantalum and TEOS–SiO2, and stronger surface defect control and surface profile correction capabilities. In this paper, the effects of guanidine hydrochloride (GH) and 2,2′-[[(Methyl-1H-benzotriazol-1-yl)methyl]imino]bisethanol (TT-LYK) system on the tunability of Ta and Cu removal rate in chemical mechanical polishing (CMP) of TSV wafer barrier material were studied. GH can complex TaO 4 3 - , while TT-LYK can form a protective film on the surface of Cu, thereby achieving rate regulation. The results showed that when the concentration of GH increased from 0 to 2 wt%, the removal rate selectivity ratio of Ta and Cu raised from 1.02:1 to 1.26:1. When the concentration of TT-LYK increased from 2.5 to 10 mmol/L, the removal rate selectivity ratio of Ta and Cu increased from 1.33:1 to 1.79:1, which verified that the GH and TT-LYK systems can efficiently regulate the rate and rate selection ratio of Ta and Cu. Surface roughness for both metals decreased from pre-polishing values of 5.03 nm to post-polishing values of 0.37 nm for Ta, from pre-polishing values of 5.33 nm to post-polishing values of 1.26 nm for Cu indicating that GH and TT-LYK systems significantly improved the surface quality. [ABSTRACT FROM AUTHOR]

This paper reports a new nondestructive noncontact method of sensing surface roughness, particularly the surface undulation produced in the plowing stage of wear. This method involves inductance measurement. It is fast, provides global information and is suitable for real-time monitoring, but it is limited to electrical conductors. This amounts to structural self-sensing. Ultramild abrasive wear primarily in the plowing regime, with areal weight loss ≤ 0.075 g/cm2 and ≤ 0.040 g/cm2 for steel and aluminum, respectively (i.e., thickness loss ≤ 0.30 mm and ≤ 0.48 mm for steel and aluminum, respectively), is effectively sensed by this method. The inductance measurement involves two electrical contacts (clips) and an LCR meter (2 kHz). The inductance increases monotonically with increasing degree of wear primarily in the plowing regime, beyond which it does not increase further. This is due to the sensitivity of the inductance to the surface undulation, as expected from Faraday's law. Longitudinal wear (wear performed in the inductance measurement direction, i.e., direction along the metal bar length) and transverse wear (wear performed along the direction perpendicular to the inductance measurement direction) give similar weight loss. However, the fractional increase in inductance due to wear is greater for transverse wear than longitudinal wear, as expected from Faraday's law. Hence, the inductance method can discern the surface undulation direction, i.e., the wear direction, but the weight loss method cannot. The fractional increase in inductance due to wear is greater for steel (magnetic) than aluminum (not magnetic). However, magnetic character is not required for the sensing. [ABSTRACT FROM AUTHOR]

The effect of surface roughness on the interfacial contact resistance (ICR) and the corrosion behavior of 446 stainless steel in simulated anode environments for proton exchange membrane fuel cell (PEMFC) (i.e., 0.5 mol L−1 H2SO4 + 2 ppm F− and 5 × 10−4 mol L−1 H2SO4 + 0.1 ppm F− bubbled with hydrogen gas at 80 °C) was investigated by means of atomic force microscopy, potentiodynamic polarization, electrochemical impedance spectroscopy and ICR test. The surface roughness (Ra) produced by mechanical grinding increases noticeably with the decrease of sandpaper grit size from 1000# to 240#. 446 stainless steel shows the active state under free corrosion conditions in the two test solutions and the passive state at the typical anode working potential of PEMFC after the activation-passivation transition. The corrosion resistance decreases with the increase of roughness in both solutions. The corrosion product films formed in the solution with lower acidity are more protective, leading to the appearance of the diffusion process. The enlargement of surface roughness results in the gradual reduction of ICR, but the acceleration of active and passive dissolutions. [ABSTRACT FROM AUTHOR]

Experimental results are presented for the contact acoustic nonlinearity of interfaces between two solid surfaces in dry contact which experience a moderate level of plastic deformation. The current research aims at investigating the effects of the elastoplastic hysteresis, surface roughness, and possible adhesive force on the acoustic nonlinearity. The ultrasonic results are compared with results from the elastoplastic contact model of Kim and Lee (2007) and the clapping model of Blanloeuil et al. (2020), which reveals that the nonlinearities are dominated by clapping of lightly contacting cracks at the interface at low pressures and by the elastoplastic nonlinear spring at high pressures. On top of this major trends, there are consistent minor trends which are attributed to the effects of adhesive force. There is a critical pressure level at which the adhesive clapping of cracks starts being more pronounced. As predicted by the model, the nonlinearity increases with the surface roughness and thus is always lower during unloading in the high pressure regime. The effects of the adhesion are investigated by measuring the nonlinearity at two different relative humidity levels. Some systematic, physically reasonable trends in the experimental results illustrates possible effects of the adhesive force on the acoustic nonlinearity. [ABSTRACT FROM AUTHOR]

The present study is focused on the synthesis of zero-valent iron/cellulose acetate (Fe0-x/CA) membranes by phase inversion route for the activation of peroxymonosulfate (PMS). The generated •OH and SO4•− effectively degraded methylene blue (MB) dye in water to give comparatively non-toxic byproducts. The SEM investigations revealed that Fe0 nanoparticles are evenly dispersed into the CA membrane resulting in decline of agglomeration and enhancing the roughness of the composite surface. Moreover, the catalytic degradation of MB demonstrated that M5-alone showed 85% and was further boosted to 97% when coupled with PMS (M5/HSO5−). The catalytic degradation of degradation of MB by M5/HSO5− membrane system in acidic, neutral, and basic media indicated that the degradation was 99.5%, 98.0%, 97.0%, 86.0% and 70.0% when the pH of the medium was 3, 5, 7, and 11, respectively. Furthermore, the degradation performance of M5/HSO5− membrane system was evaluated in de-ionized water (DIW), tape water (TPW) and industrial wastewater (IWW) and the results indicated that MB catalytic degradation was in the order of DIW (97%) > TPW (84%) > IWW (68%). Besides, various parameters like water flux permeability, contact angle, porosity, and fouling performance were also investigated. In addition, the degradation products were evaluated, and the degradation pathways were proposed accordingly. [ABSTRACT FROM AUTHOR]

The aluminum metal matrix composites (Al-MMCs), reinforced with additional elements, including silicon carbide particles (SiC), are widely used in various industrial sectors and components. The main advantages of Al-MMCs are but not limited to high hardness, strength, and lightweight, while the main disadvantages are weak machinability and high wear in cutting tools. However, the literature review denotes that only limited studies are available on the effects of different cooling and lubrication methods, especially cryonic cooling parameters, on the tool wear morphologies, tool life, and the surface quality attributes of Al-MMCs parts. In cryogenic processes, various super-cold liquids, such as nitrogen and carbon dioxide, are employed around − 200°. Therefore, in this work, the effects of both cutting and cryogenic parameters on the flank wear size and surface roughness attributes Ra, Rq, and Rz were studied in the slot milling A356-10%SiC, which has received limited attention in the literature. The statistical analysis showed that the effect of cutting and cryogenic cooling parameters on the wear size was significant (R2 = 0.97). Compared with reported works, tool life was improved by around 26% under the same cutting conditions compared to readings made under dry mode. However, despite the measurement zone, an insignificant relationship was observed between surface roughness attributes and cutting parameters. Nevertheless, regardless of the roughness measurement zone, Ra had the highest correlation of determination (R2) to variation of cutting parameters, and cryogenic pressure had the most significant effect on all studied roughness attributes. [ABSTRACT FROM AUTHOR]

Shot peening is a commonly used method of finishing machine elements in the manufacturing process. One variation of shot peening is the impulse shot peening. This paper presents the influence of impulse shot peening technological conditions on the surface roughness (parameters Ra and Rt), topography, and microhardness. The FEM was used to determine the S11 stresses. In the experiment and simulation tests, AZ31 and AZ91HP magnesium alloy samples were used. Variable parameters in the impulse shot peening process were impact energy E (15–185 mJ), ball diameter d (3–15 mm), and impact density j (3–44 mm−2). As a result of the tests carried out, it was found that after impulse shot peening, the surface topography is change, microirregularities are flattened, and numerous depressions are formed, which can be potential lubrication pockets. The 2D surface roughness parameters for most impulse shot peening conditions are lower than for the pre-machining. The roughness parameters for magnesium alloy AZ91HP are lower than for AZ31. This is most likely due to the lower elongation A. The microhardness after impulse shot peening increased by 20 to 87 HV. As a result of FEM of the impulse shot peening, compressive stresses S11 were created in the surface layer. The depth of occurrence of S11 stresses is from 1.5 to 3.5 mm, and their values for the AZ91HP magnesium alloy samples are 10 to 25% lower than for the AZ31 alloy samples. The most favorable results of the tested properties of the surface layer were obtained for E = 100 mJ, d = 10 mm, and j = 11 mm−2. The abstract serves both as a general introduction to the topic and as a brief, non-technical summary of the main results and their implications. [ABSTRACT FROM AUTHOR]

Super Duplex Stainless Steels (SDSS), in spite of their numerous commercial applications is considered to be extremely difficult to machine owing to its poor thermal conductivity, severe chemical affinity, and work hardening nature. Several studies have analysed the possibility of adopting conventional lubrication/cooling methods and coating techniques to address the machinability-related challenges of the alloy. However, limited studies have explored the use of multi-layered coatings to enhance the tool life properties while machining the alloy. Hence, this work intends to investigate the impact of using CVD TiCN-Al2O3 coated tools to analyse the significance of parameters like speed, feed rate, and depth of cut on the machinability aspects of SDSS 2507 in dry turning conditions. The experimentation analysis revealed that while speed, feed rate, and depth of cut had a significant impact on influencing the tool wear characteristics, surface roughness values were impacted by only feed rate values. Similarly, feed rate, depth of cut, and interaction effects between these factors were noted to have a considerable influence on the cutting forces. Meanwhile, the study also focuses on developing an analytical model to predict the cutting forces that consider the sticking-sliding effects by incorporating the chip groove area across the machining interface. The predicted cutting force values were observed to be in close agreement with the experimental results. The error values were noted to be below 15% in the majority of the cases, which confirms the significance of the predicted model. [ABSTRACT FROM AUTHOR]

This study concentrates on NiCrAlY-based coating with nano-boron carbide and cenosphere particles. The composition of NiCrAlY, B4C and cenosphere are maintained the same for all the samples. The plasma spray technique is used for coating. The erosive wear is carried out for different impingement angles of 30°, 60°, 75° and 90° at 900°C. The morphology of coating before and after erosive wears is studied using scanning electron microscopic analysis. Further, the study is carried out on surface roughness, scratch resistance and coefficient of friction of the eroded surface of the samples. The significant erosive wear resistance is reported for an impact angle of 60° followed by 30°. The surface roughness results reveal the formation of deep craters and the ploughing effect of material on the coatings. The scratch test and COF show the presence of coating and the brittle nature of the failure of the coating. [ABSTRACT FROM AUTHOR]

Shear thickening polishing (STP) is a finishing process that uses an non-Newtonian abrasive slurry to remove workpiece material. This method is used to polish the complex surfaces with a simple machining process. In this process, the polishing force are important factors that affect the surface roughness of workpiece. Polishing parameters are determined based on the Taguchi experimental design method. In addition, the analysis of variance (ANOVA) and regression analysis were also carried out. The polishing speed (60, 65, 70 and 75 rpm), working gap (15, 20,25 and 30 mm) and abrasive concentration (20, 25, 30 and 35 wt%) were chosen as machining parameters. In the ANOVA analysis, it was determined that the most effective parameters on force Fx/Fy/Fz values were working gap (92.86%/85.07%/90.51%), polishing speed (3.27%/11.43%/4.47%) and abrasive concentration (0.01%/0.03%/0.05%), respectively. The optimum parameter for maximum polishing force were found to be polishing speed of 75 rpm, working gap of 15 mm, and abrasive concentration of 35%. Under the optimal polishing parameter, an experimental model of STP for inner ring of angular contact spherical plain bearings has been conducted. As a result, the surface roughness Ra/Rz of inner ring is reduced from 0.08/0.53 to 0.02/0.13 μm. It was achieved about 75%/76% better. Comparing with the non-optimal STP process, the surface roughness Ra/Rz was upgraded 60%/58%. Experimental results demonstrate that the surface quality of the workpiece is significantly improved under suitable cutting force conditions. [ABSTRACT FROM AUTHOR]

In this technical paper, we present a comprehensive study on the performance of the Multiverse Optimization (MVO) algorithm combined with various machine learning models, including Decision Trees, Artificial Neural Networks, Random Forest, and XGBoost. Our primary goal is to investigate the efficacy of the MVO algorithm in enhancing the performance of these models when applied to a specific dataset and problem context. Performance metrics, such as mean squared error (MSE), mean absolute error (MAE), and R-squared value, are employed to evaluate and compare the effectiveness of each MVO-enhanced model. Our results demonstrate that the MVO-Decision Tree combination outperforms the other MVO-enhanced models, exhibiting lower MSE and MAE values and a higher R-squared value. We attribute this superior performance to several factors, including problem suitability, the metaheuristic optimization capabilities of the MVO algorithm, the simplicity and interpretability of Decision Trees, and effective model selection and hyperparameter tuning. [ABSTRACT FROM AUTHOR]

For hard-to-cut materials and composites abrasive water jet machine (AWJM) has been identified as a lucrative and competent material removal technique, in which a high-speed jet of abrasive and water strikes the workpiece surface to erode the desired material. In this paper, the influence of key input parameters (water pressure, standoff distance, traverse rate and abrasive mass flow rate) on responses such as surface roughness (Ra), kerf taper (Kt), and maximum delamination length (Max. DLL) of machined specimen during AWJM of glass fibre reinforced polymer (GFRP) composite is examined through experimental investigations. Response surface methodology (RSM) based central composite design (CCD) approach and Taguchi design based L16 orthogonal array is used for experimentation. Moreover, a hybrid approach of RSM-Desirability and Taguchi Methodology-Grey Relational Analysis (TM-GRA) are used for Multi-response optimization (MRO) and their results are compared for evaluation of process parameters of AWJM on GFRP. Confirmation tests are carried out to validate the experimental results, and they showed that using the RSM-Desirability approach, at the optimum level of parameters, the percentage errors for Ra, Kt, and Max. DLL have been less than 6.312%, 7.229%, and 6.78%, respectively. As per the results Ra, Kt and Max. DLL improves by 12.6%, 14.4% and 73.6% respectively by using RSM-Desirability approach as compared to TM-GRA. The microscopic features of optimally machined surfaces are investigated using the scanning electron microscope (SEM). [ABSTRACT FROM AUTHOR]

Iron scrap is one of the substances rejected in large quantities of by-products from the steel industrial sector. In this work, waste cellulosic fibers and iron shavings were used as reinforcement and abrasive particles, respectively. Two methods of the synthesis of the hybrid composites were applied namely spraying and coating. Different analytical techniques of characterization, i.e., Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA/DTG), and energy-dispersive X-ray (EDX), were used to analyze the studied samples. The morphology of the abrasives displayed the presence of spherical grains on the surface with a diameter ranging from 100 to 200 µm. In the spraying process, the surface was characterized by the presence of hollows, bumps, and small empty areas. For the coating process, the fibers of the reinforcement and some drops of resins were visible on the surface of the abrasives. The EDX analysis suggested that the abrading action of the composite surface might be done by tearing off the iron grains. The properties of the matrices, process considered, size of the grains, and their distribution were found to be the principal parameters governing the abrasive process. As the particle size increases, the surface becomes rougher, allowing for more scraping of the materials surfaces. [ABSTRACT FROM AUTHOR]

A standalone Advanced Circulation (ADCIRC) model for the east coast of India with a high-resolution grid of 100 m near the coast is used to evaluate coastal inundation resulting from the storm tides generated by recent cyclones. A directional surface roughness parametrization that alters wind speed and Manning's n friction coefficient to compute bottom friction based on land use/land cover (LULC) at a particular location is incorporated in the model. ERA5 reanalysis winds highlight that the cyclonic winds over the land are less intensive than nearby coastal oceans, particularly during landfall time, by approximately 29%–50%. Experiments are also designed to quantify the impact of surface and bottom friction on wind speed and the inward propagation of storm tides. A comparison of cyclonic wind speed after incorporating LULC data in the model is made with an automatic surface observation system (ASOS). It suggests a 15%–29% reduction, consistent with ASOS. The inundated area computed for the cyclones advocates a significant reduction (15%–50%) due to LULC. Sensitivity experiments with LULC are performed to examine the impact of mangroves in the Krishna estuary located in between two concave-shaped coastal geometries. Replacing wetlands with Mangroves results in a simultaneous decline in wind speed (12.5%) and inundated area (13.4%). It also highlights that bottom friction contributes (9.4%) in the inundated area against surface friction (4%). This study infers that further investigation and planning are mandatory to ensure coastal mangrove restoration initiatives and effective coastal management practices. [ABSTRACT FROM AUTHOR]

The coefficient of friction (CoF) between the deflection pulley and rope in a lift strongly affects the life span of the rope. Although surface roughness is a key factor affecting the metallic pulley–rope CoF, its effect on polymeric pulleys is unknown. The present study analyses the effect of roughness and working conditions on cast polyamide 6 (PA6G) deflection pulley–thermoplastic polyurethane (TPU)-coated rope contacts. The statistical analysis revealed that the effect of surface roughness on the CoF for low-load tests was significant. The present study contributes significantly to parameter selection in deflection pulley machining to minimise friction between the pulley and rope. [ABSTRACT FROM AUTHOR]

A novel galvanic-polishing-assisted near net shape forming was proposed to improve the heat dissipation capacity of the liquid-cooled plates. The coarsest upper surface roughness of channels was reduced from 74 to 37 μm. The coolant flow rate and heat dissipation capacity of the liquid-cooled plates with the polished channels were increased by 35.2 and 51.0 pct compared with those of untreated liquid-cooled plates, respectively. [ABSTRACT FROM AUTHOR]

This work demonstrates rapid solidification and precision machining to achieve 6061 aluminum alloys with extremely small surface roughness (2.05 nm), good tensile strength (325 MPa), and uniformly distributed coherent nanoprecipitates. The fundamental mechanisms are revealed by means of microstructural and nanomechanical characterization at multi-scales, together with atom probe tomography analysis. This work opens the way to manufacture metallic optics for astronomy, radar, and LED devices with unprecedented low surface roughness and sufficient mechanical strength. [ABSTRACT FROM AUTHOR]

This article presents a numerical investigation focused on how roughness of surface affects the overall performance of a counter-flow microchannel heat exchanger (CFMCHE). The study examines various microchannel shapes, including triangles, squares, circles, and trapezoids, to evaluate their performance within the context of CFMCHE. Water with consistent properties flows through aluminum microchannels used as the working fluid. The analysis employs the roughness-viscosity method to assess how surface roughness influences the CFMCHE’s performance. The study’s findings emphasize that the trapezoidal channel shape exhibits the most favorable performance among the shapes investigated. Additionally, among the operational parameters considered, the hydraulic diameter emerges as the most influential factor in determining the most suitable characteristics for CFMCHE. The presence of surface roughness was found to marginally improve thermal performance while slightly reducing hydraulic efficiency. This research provides valuable insights into the intricate interplay between surface roughness and channel shape. Notably, the impact of roughness is more pronounced in the case of the trapezoidal shape compared to other geometries. [ABSTRACT FROM AUTHOR]

Silicon carbide particle–reinforced aluminum matrix (SiCp/Al) composite materials are challenging to machine, leading to significant surface quality issues arising during milling. In this study, a single-factor experiment was conducted using carbide-coated tools to mill SiCp/Al composite materials with a 45% volume fraction of silicon carbide particles (SiCps). Scanning electron microscopy, roughness measuring instruments, and a three-dimensional optical profiler were employed to investigate the formation mechanisms of the machined surface morphologies, as well as the effects of milling parameters (milling speed, feed per revolution, and milling depth) on the surface micro-morphology of the SiCp/Al composite materials. This study assessed the suitability of various roughness characterization parameters for evaluating the milled surface of SiCp/Al composite materials, including the two-dimensional profile arithmetic mean deviation (Ra), profile root mean square deviation (Rq), and microscopic surface roughness 10-point height (Rz), as well as the three-dimensional arithmetic mean deviation of the surface profile (Sa), and root mean square deviation of the surface profile (Sq) roughness characterization parameters to evaluate the milled surface of the SiCp/Al composite materials. The findings suggest that the three-dimensional roughness characterization parameters more accurately reflected the changes in the surface roughness than the two-dimensional ones. When the milling speed increased from 0.05 to 1.2 mm/rev, Sa first decreased from 0.514 to 0.498 µm and then increased to 0.537 µm, while Sq first decreased from 0.637 to 0.616 µm and then increased to 0.658 µm. Ra, Rz, and Rq all increased with higher values of feed per revolution and milling depth. [ABSTRACT FROM AUTHOR]

When subjected to swift heavy ion (SHI) irradiation, a lattice acquires sufficient energy to induce desirable flaws in the material. In this study, the physiochemical properties of Sn-doped V2O5 (SVO) synthesized by a sol–gel process were thoroughly examined following irradiation with Ni+11 ions at 150 MeV energy and fluence of 2.51 × 1011 ions/cm2. The successful doping of Sn in V2O5 was confirmed by an increase in tensile strain, as revealed by the x-ray diffraction (XRD) spectrum, and the presence of characteristic peaks of constituent elements detected in the energy-dispersive x-ray (EDX) spectrum. Atomic force microscopy (AFM) and field-emission scanning microscopy (FESEM) images revealed an increase in surface roughness and transformation to an amorphous state, respectively. The Tauc plot indicated an increase in the electronic bandgap post-irradiation. Fourier transform infrared (FTIR) spectroscopy analysis revealed a peak shift in the fingerprint region indicating a change in the vibrational energy of the involved molecular bonds. These findings highlight the potential of SHI irradiation for the tuning of material properties, paving the way for a wide range of functional applications of the material. [ABSTRACT FROM AUTHOR]

The hot-compression bonding of Ti386 and TC4 titanium alloys takes place within a temperature range of 800 to 900 °C and under strains of 10–30% in this study. The analysis of Ti386/TC4 joints involves the interfacial microstructure and compression shear strength are conducted. Quantitative analysis reveals that the interfacial voids, as a consequence of surface roughness, notably decrease as deformation strains and temperatures increase, which leads to the highest shear strength 673.26 MPa at 900 °C/30%. The Ti386/TC4 interface exhibits distinct characteristics and presents two zones: αp(TC4)/β(Ti386) and αs + β(TC4)/β(Ti386). The αp(TC4) phase protrudes into the β(Ti386) side at the αp(TC4)/β(Ti386) interface due to the higher hardness of the stable primary αp(TC4). During the process of deformation bonding, dynamic recrystallization occurs within the interfacial region. On the TC4 side, dynamic recrystallization is primarily discontinuous dynamic recrystallization, initially observed in the lamellar αs + β areas before extending to the equiaxed αp areas. Conversely, on the Ti386 side, continuous dynamic recrystallization prevails, characterized by the transformation of low-angle grain boundaries to high-angle grain boundaries. [ABSTRACT FROM AUTHOR]

Laser powder bed fusion (L-PBF) fuses metallic powder using a high-energy laser beam, forming parts layer by layer. This technique offers flexibility and design freedom in metal additive manufacturing (MAM). However, achieving the desired surface quality remains challenging and impacts functionality and reliability. L-PBF process parameters significantly influence surface roughness. Identifying the most critical factors among numerous parameters is essential for improving quality. This study examines the effects of key process parameters on the surface roughness of AlSi10Mg, a widely used aluminum alloy in high-tech industries, fabricated by L-PBF. Part orientation, laser power, scanning speed, and layer thickness were identified as crucial parameters via cause-and-effect analysis. To systematically examine their effects, the Taguchi method was employed within the framework of the design of experiment (DoE). Experimental results and statistical analysis revealed that laser power, scanning speed, and layer thickness significantly influence surface roughness parameters: arithmetic mean (Ra) and root mean square (Rq). Main effect plots and energy density analyses confirmed their impact on surface quality. Microscopic investigations identified surface flaws such as spattering, balling, and porosity contributing to poor quality. Given the complex interplay between parameters and surface quality, accurately predicting their effects is challenging. To address this, machine learning models, specifically random forest regression (RFR) and support vector regression (SVR), were used to predict the effects on surface roughness. The RFR model's R2 values for predicting Ra and Rq are 97% and 85%, while the SVR model's predictions are 85% and 66%, respectively. Evaluation metrics demonstrated that the RFR model outperformed SVR in predicting surface roughness. [ABSTRACT FROM AUTHOR]

Laser-based metal powder bed fusion (PBF-LB/M) offers great potential for producing complex and filigree sub-millimetre parts with customised shapes, such as patient-specific vascular stents. However, stent fabrication via PBF-LB/M encounters fundamental challenges, including dimensional limitations, poor surface quality, difficult support structure handling and geometrical deviations. This study addresses these challenges by investigating the potential and limitations of a novel hybrid post-processing approach. This technique uses the combination of electrochemical polishing and chemical etching and is investigated from process and design perspectives, to emphasise the interactions between the two. With the systematic application of hybrid post-processing, the strut thickness and the surface roughness were substantially reduced. Moreover, it enabled the successful removal of part-internal support structures. Furthermore, angle and orientation-dependent geometrical deviations could be compensated, highlighting the potential of achieving homogenous strut thicknesses within parts containing variable overhang angles. This study demonstrates that the usage of hybrid (electro)chemical post-processing methods with specifically tailored process parameters is a promising approach for overcoming the design- and process-related challenges in PBF-LB/M manufactured sub-millimetre parts. [ABSTRACT FROM AUTHOR]

Sustainability and precision are fundamental requirements for machining processes. In this study, novel energy consumption and surface roughness models are established to support the multi-objective (sustainability and precision) optimisation of machining processes. In this study, the following innovative characteristics are exhibited: (i) a physically interpretable energy consumption model is designed by considering correlations between key machining parameters and machining powers used in different machining zones; (ii) a surface roughness model is designed based on combined machine learning models, and optimised weights for the combination are achieved using the genetic algorithm; (iii) based on the energy consumption and surface roughness models, a Pareto-based multi-objective optimisation algorithm is devised to obtain optimised machining parameters. Orthogonal experiments were conducted to validate the models and algorithm. Results show that the energy consumption model reached an average absolute percentage error of only 1.7% and an R2 determination coefficient of 99.1%. In comparison with other models, the surface roughness model designed in this study achieved the best performance (the mean absolute percentage error (MAPE) reached 2.5%, and the R2 coefficient was above 95%). The Pareto optimal solution set for machining parameters was obtained efficiently. [ABSTRACT FROM AUTHOR]

In recent years, the effectiveness of integrating machine learning methods to predict surface roughness in machining processes has become well-established. However, there is a noticeable gap in the literature concerning the inclusion of tool wear as an input variable. In this context, this study proposed an innovative approach by including tool flank wear as an input variable along with cutting speed, feed rate, and depth of cut to train three machine learning models: Decision Tree Regression, Random Forest, and Support Vector Regression. These models aim to predict surface roughness during the dry turning of hardened AISI 52100 steel. As a result, all three models exhibited high prediction accuracy, with R-squared values exceeding 90% and lower values for both the Mean Absolute Error (MAE) and Root Mean Square Error (RMSE). However, the Random Forest model outperformed the others, boasting the lowest RMSE and MAE values of 0.05 and 0.038, respectively, alongside the highest R-squared value of 0.91. The confirmation runs demonstrated the accuracy of the Random Forest model, with actual roughness values very close to those predicted (variation of ± 0.01 μm). The correlation analysis revealed that roughness is correlated with feed rate and flank wear. This outcome underscores the importance of including tool wear as an input variable for roughness modeling. Since roughness prediction depends on the tool wear level, it is feasible to forecast the roughness of parts machined using the same cutting edge until flank wear reaches 0.30 mm (end of life). By anticipating and understanding roughness behavior as wear progresses, decision-makers can choose cutting configurations that ensure parts meet specifications, thus avoiding rework and scrap. [ABSTRACT FROM AUTHOR]

Axial ultrasonic vibration-assisted micro-milling (UVAM) has emerged as an advanced technique that can be tailored to improve the machinability of difficult-to-machine materials such as 316L stainless steel. This article sets out to meticulously compare and analyze the cutting performance of conventional milling (CM) and UVAM techniques in the side milling of 316L stainless steel. The cutting separation characteristics of UVAM of 316L stainless steel are elucidated, and the air-cutting ratio in UVAM is introduced. The relationship between the air cutting ratio and spindle speed is also derived. Based on theory, the finite element simulation and experiments are compared under both milling conditions. An analysis of the results for these two sections is presented to validate the theoretical derivation. The results show that the trend and analysis of the experimental cutting forces are aligned with those in the simulation. The cutting forces also confirm the reliability of the simulation results. Due to factors such as tool wear, there is a deviation of 5–20% between the experimental values and the simulation results. A chip variation analysis in the simulation also corresponds to the trend in cutting temperature. An evaluation of the surface morphology and roughness of the experimental samples reveals that the surface quality and smoothness under UVAM are superior to those under CM. Tool wear analysis indicates that the carbide tool undergoes severe wear in the side milling of 316L stainless steel. In summary, the simulation and experiments convincingly demonstrate the advantages of UVAM technology and provide a reference for optimizing the milling process of challenging materials. [ABSTRACT FROM AUTHOR]

This in vitro study aimed to investigate potential changes in the color and roughness of dental enamel resulting from the use of different toothpaste formulations during bleaching with violet LED light (405 nm). Sixty specimens of bovine incisors, each measuring 6 × 6 × 3 mm, were segregated into six distinct experimental groups based on their respective treatments (n = 10): C + VL: Brushing with Colgate® Total 12 + bleaching with violet LED; LB + VL: Brushing with Colgate® Luminous White Brilliant + bleaching with violet LED; LI + VL: Brushing with Colgate® Luminous White Instant + violet LED bleaching; C: Brushing with Colgate® Total 12; LB: Brushing with Colgate® Luminous White Brilliant; LI: Brushing with Colgate® Luminous White Instant. The examined variables included alterations in color (∆L*, ∆a*, ∆b*, ∆Eab, and ∆E00), surface roughness (Ra), and scanning electron microscopy observations. No statistically significant distinctions emerged in total color variations (∆E00 and ∆E) among the groups under scrutiny. Notably, the groups that employed Colgate® Luminous White Instant displayed elevated roughness values, irrespective of their association with violet LED, as corroborated by scanning electron microscopy examinations. It can be concluded that whitening toothpastes associated to violet LED do not influence the color change of dental enamel in fifteen days of treatment. Toothpastes with a higher number of abrasive particles showed greater changes in enamel roughness, regardless of the use of violet LED. [ABSTRACT FROM AUTHOR]

The existence of striations, and scratches in Abrasive waterjet (AWJ) cutting surface necessitates an exploration of these features for enhancing the cutting accuracy of AWJ machining. This article investigates surface roughness and micro-scratch morphology characteristics on brass cutting surfaces. According to the variation law of surface roughness values, the cutting section can be divided into three regions: the initial region, smooth region, and rough region. Numerous micron-scale scratches were observed in the cutting section. The scratch length, width, and depth values all show an increasing trend as the cutting depth increases, with the scratch length experiencing the greatest growth and variability. The influence of position and traverse speed on scratch size was studied using variance analysis. Furthermore, the length and width of the scratches on the cutting surface are significantly influenced by their position, accounting for 89.19% and 81.13%, respectively. Traverse speed had a minor effect on scratch length and width, accounting for 0.01% and 2.64% respectively. The depth of the scratches is influenced by their position on the cutting surface at a rate of 41.12%, while traverse speed had an impact of 38.10%. Finally, a mathematical method based on standard scores was proposed to assess the quality of the cutting section based on micro-scratch dimension. [ABSTRACT FROM AUTHOR]

Rehabilitation of pulpotomized primary molars with an appropriate restoration is essential for recovering function and safeguarding the durability of the treatment. This study aimed to assess and compare the surface roughness of stainless steel (ST) crowns, zirconia (ZR) crowns, fiberglass (FG) crowns, and lithium disilicate (LD) endo-crowns as a restoration for pulpotomized primary molars also, evaluating the surface roughness of their antagonists. Sixty pulpotomized primary mandibular first molars were used for qualitative surface roughness evaluation and divided into four groups (n = 15/group) according to the crown type (group-ST, group-ZR, group-FG, group-LD). While the other sixty sound, unprepared primary maxillary first molars were used for evaluation of their surface roughness against the tested crowns. Specimens' preparation and cementation were carried out according to each crown type and manufacturer's instructions. The surface roughness was done using a two-body wear test. The data were statistically analyzed. All tested crowns showed an increased change in surface roughness, except group-ZR, which had the least change in surface roughness after mechanical wear with no statistically significant difference(P = 0.681). All crown types significantly increased the surface roughness of their antagonists after mechanical wear, except group-ST which showed insignificant affection (p ≥ 0.05). Zirconia crowns and lithium disilicate endo-crowns had the least change in surface roughness compared to other groups while SSCs showed the least tooth loss in the antagonist enamel. [ABSTRACT FROM AUTHOR]

Plasma electrolytic oxidation (PEO) coating on Zr alloy was prepared, and the corrosion behavior was investigated under 400 °C/10.3 MPa steam condition. The surface morphology, roughness, element distribution, and microstructure of PEO coating after corrosion were analyzed. The results indicate that the PEO coating after corrosion presents the typical pores and pancake structure feature, and the surface roughness of PEO coating decreases after corrosion. The PEO coating corroded for 45 days shows the best electrochemical performance because the newly formed oxide gathers to repair the pores and cracks in the oxide/metal interface. The corrosion resistance of PEO coating decreases with the corrosion time increase because the microcrack in PEO coating is connected to generate a large transverse crack, and the corrosion media can access to oxidize the substrate through the crack during the long-term corrosion process. [ABSTRACT FROM AUTHOR]

TiN coatings are one of the most widely used nitride coatings. The introduction of the light metal element Si has led to the formation of TiN-Si3N4 coatings with a two-phase nanocomposite structure. However, the high friction coefficient of TiN-Si3N4 coatings at room temperature limits their application. In order to further improve its lubrication properties, we tried to incorporate the lubricating phase Ag. TiN-Si3N4-Ag composite coatings were prepared using a multi-target magnetron sputtering by fixing the Ti-Si target power and adjusting the Ag target power. Their microstructure, mechanical and tribological properties depending on the Ag target power were investigated. The results showed that the TiN-Si3N4-Ag composite coatings exhibited the crystalline TiN and Ag phase, and amorphous Si3N4 phase. The increasing Ag target power increased the coating surface roughness from 7 to 52 nm. The nano-hardness (H), elastic modulus (E), resistance against elastic strain to failure (H/E), and the resistance against plastic strain to failure (H3/E2) of the TiN-Si3N4-Ag composite coating first increased and then decreased with the increase of Ag target power. As the Ag target power was 10 W, the hardness (9.43 ± 0.45 GPa), elastic modulus (265.29 ± 13.3 GPa), H/E (0.036), and H3/E2 (0.0119 GPa) of the TiN-Si3N4-Ag composite coating reached the maximum values, indicating this coating exhibiting the better mechanical properties. After adding Ag, the coating exhibited better lubricating effect, while the wear resistance of the coating increased. [ABSTRACT FROM AUTHOR]

Titanium alloy Ti6Al4V is widely used in the production of bone implants due to its favorable mechanical properties and biocompatibility. However, implant failures still occur due to lack of osseointegration, tissue infection, and fatigue. Laser shock peening (LSP) is a surface treatment method that can improve the physical, mechanical, and biological properties of Ti6Al4V implants. This method enhances the fatigue life of implants by inducing compressive residual stress on their surface region. In this study, Ti6Al4V samples were subjected to LSP treatment using different laser power densities (9.6 and 14.9 GW / cm 2 ) and with (vinyl tape and commercial black color) and without a protective layer. LSP-treated samples with higher power density exhibited maximum compressive residual stresses. Furthermore, hydrophobicity increased in all samples with increasing laser power density. Notably, the surface roughness results demonstrated significant improvement where the roughness increased with increasing the laser power density. The sample without a protective layer exhibited the highest surface roughness, followed by the black color coated and vinyl tape surface protected samples. The residual stress, surface roughness, and hydrophilicity of the samples were evaluated to determine the optimal LSP parameters. Fatigue tests revealed a remarkable enhancement in the fatigue life of the LSPed samples compared to untreated samples (3 and 2.9 times longer life for black-color coated and without coating samples, respectively). Moreover, the microstructure of laser peening samples and the fracture surface of the fatigue samples were characterized using field emission scanning electron microscopy (FE-SEM). To evaluate the biological characteristics of the optimal LSP-treated samples, a hydroxyapatite coating was applied, and their biological characteristics, including cell viability and adhesion, were investigated. Furthermore, the combination of LSP with hydroxyapatite coating offers a potential solution to promote osseointegration and reduce implant failures. [ABSTRACT FROM AUTHOR]

Achieving optimal bonding to translucent zirconia poses certain challenges as there is no consensus on ideal surface treatment method. Therefore, the aim of present investigation is to evaluate effect of Er:YAG laser treatment on wettability, surface roughness and shear-bond strength of three Yttrium oxide-stabilized zirconium-oxide polycrystal translucent zirconias. 120 specimens (n = 40/zirconia type) were prepared from three commercially-available translucent zirconias (Dentsply Sirona, USA); Translucent, High-Translucent and Ultra-Translucent zirconia. Specimens were sub-divided (n = 20/surface-treatment) into control and Er:YAG laser surface-treated groups. Regarding water wettability test; goniometer was used to measure contact angle before and after laser treatment. Surface roughness was measured using atomic force microscope. For shear-bond strength (SBS) test; the control group was sandblasted. All resin-bonded zirconia specimens were thermocycled for 5000 cycle and subjected to shear force using universal testing machine with 0.5 mm/min crosshead-speed. Results were statistically analyzed using two-way-analysis-of- variance (p ≤ 0.05). There was significant decrease in average contact angles (p-value < 0.001) in all zirconia groups after laser treatment. For roughness test; insignificant difference in average Ra in Translucent zirconia group. However, significant increase in mean Ra was revealed after laser treatment for High and Ultra-Translucent zirconias. For SBS test, results revealed insignificant difference in average bond strength after laser treatment in Translucent and High-translucent zirconia groups. Significant increase in mean bond strength of Ultra-Translucent zirconia was recorded. Er: YAG laser treatment significantly affected surface properties and shear-bond strength of Ultra-Translucent zirconia. Er:YAG laser irradiation may be a promising zirconia surface treatment method. [ABSTRACT FROM AUTHOR]

Particle geometric is a key parameter that defines the eometric attributes of calcareous sand particles and is intricately related to their mechanical traits, such as compression and shear. The scanning electron microscopy and digital imaging were applied to capture the microscopic properties and geometric projections of calcareous sand. The qualitative analysis, conventional statistical methods and fractal theory were employed to describe the geometric morphology of sand particles. Additionally, we analyzed the structural and physical traits of calcareous sand based on its unique biological genesis. We developed a hypothetical structural-physical model for calcareous sand. Our findings revealed the interwoven reticulation on the surface of calcareous gravel particles, along with an uneven distribution of pores on the external surface. As the particle size increased, the global profile factor decreased and the angularity increased. The critical threshold for the variations in flatness, surface roughness, and circularity was observed at a particle size of 5 mm, with the particle size having a relatively minor effect on these characteristics for particles smaller than 5 mm. The shape of the calcareous sand particles exhibited fractal characteristics, with fractal dimension serving as a measure of surface smoothness, particle breakage, and strength. These experimental results could significantly enhance our understanding of the mechanical behavior of calcareous sand. [ABSTRACT FROM AUTHOR]

Resin cement integrated with zein-incorporated magnesium oxide nanoparticles has previously been found to inhibit oral microbes and decrease bacterial biofilm. However, the bond strength and surface features of this biomaterial have yet to be investigated. The objective of this study was to evaluate the shear bond strength, mode of fracture, and surface roughness of resin cement modified with zein-incorporated magnesium oxide nanoparticles. Characterization of the cement was performed by X-ray diffraction, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. 126 human teeth were divided into 3 groups and cemented to lithium disilicate ceramic using resin cement with zein-incorporated magnesium oxide nanoparticles at concentrations of 0%, 1%, and 2% (n = 42). 21 samples of each group were subjected to the shear bond strength test, while the other 21 underwent thermocycling for 10,000 cycles before the test, after which all samples were evaluated for the mode of fracture. To assess surface roughness, resin cement disks were analyzed by a profilometer before and after undergoing thermocycling for 10,000 cycles. The shear bond strength of the cement with 1% and 2% nanoparticles was significantly higher than the control before thermocycling. The mode of fracture was found to be mainly adhesive with all groups, with the unmodified cement presenting the highest cohesive failure. There was no significant difference in surface roughness between the groups before or after thermocycling. The addition of zein-incorporated magnesium oxide nanoparticles to resin cement improved or maintained the shear bond strength and surface roughness of the resin cement. [ABSTRACT FROM AUTHOR]

The study investigates the impact of mechanical cleaning, citric acid+sodium hydroxide (CA), and nitric acid (NA) passivation on welded SS304 stainless steel plates, taking into consideration surface roughness. An innovative EIS paste–based cell is employed for this purpose. Welded systems in both the heat-affected (HAZ) zone and base metal (BM) are being analyzed before and after each treatment. Specifically, one welded plate underwent mechanical cleaning, another was solely subjected to CA passivation, and a third received both mechanical cleaning and CA passivation. Aging tests were conducted in a condensation chamber to confirm the effectiveness of cleaning and passivation treatments. Regarding open-circuit potential (OCP), most samples remained within the passive region, except for the mechanically cleaned heat-affected zone and the intentionally abraded surface immediately after abrasion. Rp values, which are in line with the OCP measurements, range from 104 to 107 Ω cm2 for all the observed samples. As the degree of abrasion on the NA-passivated surface increases, the electrochemical impedance spectroscopy (EIS) spectrum shifts from that characteristic of the passive towards that characteristic of the active state of the stainless steel. [ABSTRACT FROM AUTHOR]

Electrochemical machining (ECM) is one of the most ideal machining methods for difficult-to-cut material of U71Mn alloy. Therefore, it is vital to obtain the electrochemical characteristics of the material. In this paper, these characteristics are measured with an electrochemical station, and a series of experiments are conducted to verify them. The electrolyte solutions of 15 wt.% NaNO3 and 15 wt.% NaCl are selected for the experiments. The polarization experimental results indicate a broader range of passive regions in the NaNO3 electrolyte solution compared with that in the NaCl. This means that a higher voltage is required to break down the passive film in ECM experiments. Meanwhile, the current efficiency of the alloy is measured in 15 wt.% NaNO3 and 15 wt.% NaCl. The results indicate that the current efficiency of U71Mn alloy in NaCl electrolyte solution is higher than that in NaNO3 electrolyte solution. The electrochemical characteristics of U71Mn alloy are verified with a series of single-factor experiments, and reasonable machining parameters are obtained. The suitable range of machining voltage is 10 to 20 V, and the range of inter-electrode gap is 0.1 to 0.2 mm in these two electrolyte solutions. Finally, multi-parameter experiments are carried out in these two electrolyte solutions to obtain machining samples. The experimental results show that 15 wt.% NaNO3 proved to be a better electrolyte solution for U71Mn alloy, the surface roughness (SR) of the workpiece is Sa 0.72 μm, and the material removal rate (MRR) is 0.096 g/min. [ABSTRACT FROM AUTHOR]

Most wet-type multi-path ultrasonic flowmeters have their measurement accuracy rate deteriorate as the flow rate is decreased. Curve-fitting on the characteristics of ultrasonic flowmeters is essential to improve their measurement accuracy rate. This hinders their use as transfer standards in inter-laboratory comparisons for water flow metrology. A breakthrough to enhance the measurement accuracy rate of ultrasonic flowmeters is needed. This study suggests that the concept of near-wall flow velocity should enhance the characteristics of ultrasonic flowmeters. As a result, repeatability can be improved as low as ±0.02 %, which should be suitable to be used as transfer standards. Two main points of using the near-wall flow velocity for ultrasonic flowmeters are emphasized. One is a formula to describe the near-wall flow velocity as a function of both Reynolds number and surface roughness. The other is the results of comparison calibrations between two national metrology institutes, which can support measurement equivalence. In particular, the number of equivalence is less than one (∣En∣ ≤ 1), and the inconclusiveness parameter is less than two (ucomp/ubase ≤ 2) if the near-wall flow velocity is applied for ultrasonic flowmeters. This implies that the ultrasonic flowmeters could be used as transfer standards for the forthcoming inter-laboratory comparisons. [ABSTRACT FROM AUTHOR]

Recently, we have developed an algorithm to quantitatively evaluate the roughness of spherical microparticles using scanning electron microscopy (SEM) images. The algorithm calculates the root-mean-squared profile roughness (RMS-RQ) of a single particle by analyzing the particle's boundary. The information extracted from a single SEM image yields however only two-dimensional (2D) profile roughness data from the horizontal plane of a particle. The present study offers a practical procedure and the necessary software tools to gain quasi three-dimensional (3D) information from 2D particle contours recorded at different particle inclinations by tilting the sample (stage). This new approach was tested on a set of polystyrene core-iron oxide shell-silica shell particles as few micrometer-sized beads with different (tailored) surface roughness, providing the proof of principle that validates the applicability of the proposed method. SEM images of these particles were analyzed by the latest version of the developed algorithm, which allows to determine the analysis of particles in terms of roughness both within a batch and across the batches as a routine quality control procedure. A separate set of particles has been analyzed by atomic force microscopy (AFM) as a powerful complementary surface analysis technique integrated into SEM, and the roughness results have been compared. [ABSTRACT FROM AUTHOR]

Fluid injection associated with unconventional resource extraction activities can alter the friction-permeability relationship of fractures, thereby significantly affecting the stability of fractures/faults. In this study, we utilized the three-dimensional (3D) carving technique to reconstruct natural shale fractures recovered from the Longmaxi shale reservoir at a depth of 3700 m in the southeastern Sichuan Basin. Subsequently, we conducted friction-permeability coupling experiments to elucidate the relationship between friction, permeability, and stability for natural shale fractures. In the experiments, confining pressure was maintained at 3 MPa, temperature was maintained at 25 °C, the constant shearing velocity was set to 1 μm/s, and the velocity step was set to 10–1–10–1–10 μm/s. Our results show that the frictional coefficient of natural Longmaxi shale fractures ranges from 0.67 to 0.71, which is higher than that of saw-cut fractures of 0.61–0.62. Furthermore, frictional stability parameter (a–b) of the natural Longmaxi shale fracture exhibits velocity strengthening behavior under all conditions, indicating aseismic slip possibly caused by the abundant phyllosilicate content in shale fractures. However, the decrease of roughness and the effect of fluid injection reduce the frictional coefficient of natural fractures during the shearing process. At the same time, fluid injection reduces frictional stability, leading to a transition from velocity strengthening to velocity neutral. In addition, the increase in permeability of the natural fracture is more pronounced due to the velocity step shear compared to constant velocity shear. We confirm that fracture stability is influenced by a combination of factors including fracture surface roughness and fluid injection. Highlights: Three-dimensional (3D) scanning and carving techniques were employed to reproduce natural Longmaxi shale fractures. Fluid injection leads to a transition of frictional stability from velocity strengthening to velocity neutral. Frictional coefficient and stability of shale fractures are affected by both roughness and fluid flow. Compared with constant velocity shear, velocity step shear has more obvious effect on permeability enhancement. [ABSTRACT FROM AUTHOR]

Stability of fiber-reinforced shotcrete (FRS)-rock interface under high-and-variable temperature conditions during high geothermal tunnel construction is related to the safety of tunnel support. The rough rock specimen preparation method and the high-and-variable temperature conservation model were proposed based on the tunnel environment. In the present work, direct shear tests were conducted on composite specimens of FRS and rock, which were subjected to high-and-variable temperature curing (with initial curing temperatures of 46, 57, and 71 °C) and different levels of normal stress (0.5, 1.0, and 2.0 MPa). The characteristics of roughness surface changes before and after shear were analyzed based on industrial type optical surface scanning. The acoustic emission (AE) of the shear process of the combined test and the microscopic characteristics of the concrete under high-and-variable temperature curing conditions were investigated. The main findings are as follows. (1) The curing temperature, normal stress, and roughness exert significant influences on both the shear strength and failure mode of the interface between rock and FRS. Shear strength was reduced by 36% and shear displacement by 30.7% at an initial curing temperature of 71 °C compared to 46 °C at an interface height of 0.35 mm and a normal stress of 1 MPa. The interface protrusion height of 0.35 mm and the initial curing temperature of 46 °C increased the normal stress from 0.5 to 2.0 MPa, the shear strength increased by 65%, and the shear displacement increased by 28%. The shear strength increased by 28%, shear displacement decreased by 39%, and the number of AE events at the peak shear stress increased by a factor of 11 for specimens with a normal stress of 0.5 MPa, an initial curing temperature of 46 °C, and a bulge height of 3 mm relative to 0.35 mm. (2) The post-peak evolution of shear stress can be categorized into four types: fast drop, fast drop followed by rebound, fast then slow drop, fast then slow drop with fluctuations. (3) Shear failures at the interface and on the rough rock surface primarily occur on the concrete side, and the influence of the initial curing temperature on the failure mode weakens with increasing roughness and normal stress. (4) The inclusion of alkali-resistant glass fiber (AR-GF) mitigates the detrimental effects of high temperature on concrete and concurrently enhances the shear strength of the interface between rock and FRS. These research findings can provide valuable insights and support for the investigation, design, and construction of FRS support systems in high-temperature underground engineering projects. Highlights: The rough rock specimen preparation method based on 3D scanning and 3D engraving and the high-and-variable temperature curing model were proposed. Shear mechanics and acoustic emission characteristics of the shotcrete-rock interface after high-and-variable temperature curing were investigated. The rough surface analysis method based on industrial surface scanning was proposed to study the characteristics of rock rough surface changes. The effect of initial curing temperature on the shear strength of the shotcrete-rock interface decreases with increasing normal stress and roughness. [ABSTRACT FROM AUTHOR]

In order to investigate geophysical indicators of permeability changes in subsurface fractures, we conducted an experimental study on the hydraulic–mechanical–seismic coupled behaviors of granite fractures with surface roughness under stress conditions during hydraulic shearing. Our laboratory experiment yielded the following insights: (1) The "self-propping shear slip concept" unequivocally serves as the primary mechanism for maintaining the increase in fracture permeability of granite, even under stress conditions exceeding approximately 50 MPa. (2) The Gutenberg–Richter b-value gradually decreases during shear dilation and accompanying increase in fracture permeability. Thus, it could serve as an indicator for assessing changes in fracture permeability. (3) The evolution amplitude in acoustic emissions (AEs), as well as the classification of tensile/shear modes and the timing of our maximum amplitude of AE occurrence, do not seem to provide useful information for estimating fracture permeability changes during hydraulic shear slip. The reduction in b-value can be attributed to the spontaneous formation of preferential flow paths during the injection of pressurized fluid into the rock fracture and the subsequent detachment of the small contacting asperities due to localized shear slips, which naturally lead to the creation of porosity and irreversible increase in fracture permeability. Highlights: Hydraulic-mechanical-seismic coupled behaviors of granitic fracture are investigated during hydraulic shearing experiments in the laboratory. b-value gradually decreases during shear dilation and associated permeability increase of granitic fracture with rough surfaces. There is no clear correlation between fracture permeability change and amplitude/occurrence timing of AEmax amp. during hydraulic shearing. [ABSTRACT FROM AUTHOR]