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To observe the chemical mechanical polishing (CMP) process at the atomic scale, reactive force field molecular dynamics (ReaxFF-MD) was employed to simulate the polishing of 6 H-SiC under three conditions: dry, pure water, and H2O2 solution. This study examined the reactants on the surface of 6 H-SiC during the reaction in the H2O2 solution, along with the dissociation and adsorption processes of H2O2 and water molecules. The mechanisms for atom removal during the CMP process were elucidated. Variations in the number of different bonds over time and changes in the number of amorphous SiC atoms across various environments were analyzed. A comparison was made regarding the surface morphology of SiC after polishing with diamond abrasives in the three distinct environments.The results indicate that H2O2 and water molecules can dissociate into -OH, -H, and -O-. Si atoms form Si-C bonds with carbon atoms in the abrasive or connect with carbon atoms via -O- bridges to form Si-O-C for removal. C atoms are primarily removed in the form of carbon chains. Abrasive grinding can promote the dissociation of -H2O and -OH. Both water and H2O2 solutions can mitigate surface structural damage during the polishing process, with the H2O2 solution showing superior effectiveness. [ABSTRACT FROM AUTHOR]

In this work, the cost-effective precision finishing of electroless nickel plating using a compliant tool is presented. The shape adaptive grinding (SAG) process with diamond abrasive polishing pad is used for finishing of a plated surface on a stainless-steel substrate. The variable parameters in the SAG are tool compression, rotational speed of the tool, and particle size of diamond abrasive pads (9, 15, and 30 µm). Forces acting on the workpiece and areal surface roughness are the output parameters. Diamond abrasive pads are characterized for particle distribution and topography. Detailed topographical analysis of abrasive pads provides a better understanding of the change in surface characteristics and material removal mechanism with the different abrasive sizes. It is observed that fine diamond abrasive pads generate low surface roughness, while medium and coarse pads have higher wear resistance. The final finishing is performed at the optimal process parameters, and the final areal surface roughness of 7 nm is achieved. The topography, morphology, and wettability of the surface after finishing are analysed to correlate the effect of operating conditions. The article also highlights the pad loading and abrasive wear that significantly affect the outcome of the polishing process. [ABSTRACT FROM AUTHOR]

In the grinding process, acceleration signals in both the time and frequency domains are valuable for monitoring and controlling vibration patterns, as factors such as rotational speed and the grinding head design significantly influence machining quality, efficiency, and finishing performance. This study analyzes the acceleration signals by dividing them into three distinct stages, pairing this analysis with microscopic morphology to investigate the grinding behavior of carbon fiber-reinforced polymer (CFRP). The findings reveal that high-frequency and low-amplitude vibrations enhance polishing efficiency and quality, whereas low-frequency and high amplitudes adversely affect grinding quality. Acceleration vibrations are more stable during the intermediate grinding stage compared to the initial and final stages, which helps reduce surface roughness, regardless of the rotational speed or grinding head mesh size. In addition, a coarse mesh (#40) results in an uneven surface due to a large amount of removed material, whereas a fine one (#120) results in lower material removal but continuous vertical vibrations due to the impact with the grinding surface, also resulting in poor surface quality. Thus, controlling the tool's size and rotational speed is essential in reducing the amplitude of the vibration, allowing for maximizing the grinded CFRP surface quality. [ABSTRACT FROM AUTHOR]

A novel approach to enhancing the efficacy and surface quality of magnetic polishing involves the incorporation of a magnetic liquid circulation system for abrasive particle regeneration in conjunction with a circular Halbach array. The continuous renewal of abrasive particles within the polishing zone is realised through a conveyor belt that transports new abrasive particles into the polishing liquid solution. This formation of a continuously circulating polishing system ensures uninterrupted magnetic finishing processes and maintains stability throughout the polishing operation. This study extensively explores polishing force distribution, magnetic field distribution and abrasive grain behaviour in the polishing area facilitated by the magnetic liquid solution. The application of the proposed polishing processes to polymethyl methacrylate, an optical lens material, aims to comprehend the characteristics and validate the feasibility of the polishing method. Key influencing factors in the magnetic polishing process, including abrasive grain size, magnetic particle, polishing distance and conveyor speed to surface quantity, are examined through experimental analysis. Results of the experimental polishing processes demonstrate that the utilisation of circular Halbach arrays with circulating abrasives produces a nanometric surface finish. Even in the polishing of polymethyl methacrylate with an initial rough surface (Ra = 464.895 nm), the process achieves an ultra-fine level with Ra below 9 nmwithout disruption in the material polishing processes of optical lenses. [ABSTRACT FROM AUTHOR]

In an effort to mitigate anthropogenic climate impacts the U.S. has established ambitious Nationally Determined Contribution (NDC) targets, aiming to reduce greenhouse gas emissions by 50% before 2030 and achieving net-zero emissions by 2050. Enhanced rock weathering (ERW)—the artificial enhancement of chemical weathering of rocks to accelerate atmospheric CO2 capture—is now widely seen as a potentially promising carbon dioxide removal (CDR) strategy that could help to achieve U.S. climate goals. Grinding rocks to smaller particle size, which can help to facilitate more rapid and efficient CO2 removal, is the most energy-demanding and cost-intensive step in the ERW life cycle. As a result, accurate life cycle analysis of ERW requires regional constraints on the factors influencing the energetic and economic demands of feedstock grinding for ERW. Here, we perform a state-level geospatial analysis to quantify how carbon footprints, costs, and energy demands vary among regions of the coterminous U.S. in relation to particle size and regional electricity mix. We find that CO2 emissions from the grinding process are regionally variable but relatively small compared to the CDR potential of ERW, with national averages ranging between ~5–35 kgCO2 trock−1 for modal particle sizes between ~10–100  μm. The energy cost for feedstock grinding also varies regionally but is relatively small, with national average costs for grinding of roughly 0.95–5.81 $ trock−1 using grid mix power and 1.35–8.26 $ trock−1 (levelized) for solar PV for the same particle size range. Overall energy requirements for grinding are also modest, with the demand for grinding 1 Gt of feedstock representing less than 2% of annual national electricity supply. In addition, both cost and overall energy demand are projected to decline over time. These results suggest that incorporating feedstock grinding into ERW deployment at scale in the coterminous U.S. should generally have only modest impacts on lifecycle emissions, cost-effectiveness, and energy efficiency. [ABSTRACT FROM AUTHOR]

Aspherical surfaces, with their varying curvature, minimize aberrations and enhance clarity, making them essential in optics, aerospace, medical devices, and telecommunications. However, manufacturing these surfaces is challenging because of systematic errors in CNC equipment, tool wear, measurement inaccuracies, and environmental disturbances. These issues necessitate precise error compensation to achieve the desired surface shape. Traditional methods for spherical optics are inadequate for aspherical components, making accurate surface shape error detection and compensation crucial. This study integrates advanced metrology with optimized material removal functions in the grinding and polishing processes. By combining numerical control technology, computer technology, and data analysis, we developed CAM software (version 1) tailored for aspherical surfaces. This software uses a compensation correction algorithm to process error data and generate NC programs for machining. Our approach automates and digitizes the grinding and polishing process, improving efficiency and surface accuracy. This advancement enables high-precision mass production of rotationally symmetrical aspherical optical components, addressing existing manufacturing challenges and enhancing optical system performance. [ABSTRACT FROM AUTHOR]

Development of novel abrasive systems with functional activities and physicochemical properties are of great significance in the reactive oxygen species (ROS)-enhanced chemical mechanical polishing. In this work, Ce single-doped and Ce/Cu co-doped dendritic mesoporous silica nanoparticles (DMSNs), namely Ce−DMSNs and Ce/Cu−DMSNs, were produced via a simple impregnation and thermolysis procedure. The Ce and/or Cu species involved in DMSNs frameworks were characterized through X-ray diffractometry, infrared spectroscopy, scanning electron microscopy, energy dispersive spectrometry, transmission electron microscopy, X-ray photoelectron spectroscopy, and nitrogen adsorption/desorption techniques. We report the evolution of surface morphology and roughness, defects, peak-to-valley data, image surface area difference, and material removal efficiency during ROS-enhanced polishing experiments toward silica materials. All the pure, Ce single-doped, and Ce/Cu co-doped DMSNs abrasive systems offered nearly defect-free surfaces with close-to-atom scale roughness. It might be attributed to the "springlike effect" and "soft polishing/abrasion", possibly originating from the low-modulus DMSNs carriers. Among these abrasives, the Ce/Cu co-doped DMSNs systems achieved an evident improvement in removal efficiency, especially under ultraviolet irradiation-assisted polishing conditions. The coexisted Ce(Ⅲ)/Ce(Ⅳ) and Cu(Ⅰ)/Cu(Ⅱ) couples might be responsible for the effective production of ROS in photocatalysis and Fenton-like processes, thereby contributing to the Si–OH and Ce(Ⅲ)−O–Si bonding formations. The role of the developed Ce/Cu co-doped DMSNs abrasive systems in ROS-enhanced polishing processes was discussed. [ABSTRACT FROM AUTHOR]

The chemical action mechanism in the chemical mechanical polishing of SiC substrate remains elusive, which has great limitations on the selection of polishing solution and polishing parameters. In this paper, the cutting process of unreacted SiC (U–SiC) and the SiC reacted with H 2 O (R-SiC-H 2 O) and H 2 O 2 (R-SiC-H 2 O 2) was studied with an individual diamond abrasive particle by molecular dynamics simulation. The influence of chemical reaction and cutting speed on the material removal of SiC was explored by focusing on the removal rate, surface quality, machining temperature and machining stress. The simulation results showed that the number of removed atoms increased, and the surface roughness and subsurface damage depth decreased for SiC at the same cutting speed after the chemical action. Although the number of removal atoms increased with the increase of cutting speed, the surface roughness and subsurface damage depth increased at the same time. The effects of the polishing medium on the material removal process for SiC can be attributed to the decrease of surface hardness and Si–C bonding energy after the reaction of the polishing medium and SiC. The results provide a guidance for the selection of chemical mechanical polishing systems and machining parameters. • The chemical role of polishing agent is revealed, which helps us master the material removal rules of SiC and increases its material removal rate. • A new phenomenon is found that the dislocation decreases and even disappear with the rise of cutting speed, which may help us obtain damage free SiC. • Load is taken as the controlling factor in polishing. Taking normal load as controlling parameter is in line with the traditional habit in SiC CMP. [ABSTRACT FROM AUTHOR]

As an important indicator of the surface quality of workpieces, surface roughness has a great impact on production costs and the quality performance of the finished components. Effective surface roughness prediction can not only increase productivity but also reduce costs. However, the current methods for surface roughness prediction have some limitations. On the one hand, the prediction accuracy of classical experimental and statistical-based surface roughness prediction methods is low. On the other hand, the results of deep learning-based surface roughness prediction methods are uninterpretable due to their black-box learning mechanism. Therefore, this paper presents an ensemble learning with a differential evolution algorithm, applies it to the prediction of surface roughness of abrasive water jet polishing (AWJP), and conducts an interpretability analysis to identify key factors contributing to the prediction accuracy of surface roughness. First, we proposed automatically constructing features by an Evolution Forest algorithm to train the base regression models. The differential evolution algorithm with a simplified encoding mechanism was then used to search for the best weighted-ensemble to integrate the base regression models for obtaining highly accurate prediction results. Extensive experiments have been conducted on AWJP to validate the effectiveness of our proposed methods. The results show that the prediction accuracy of our proposed method is higher than the existing machine learning algorithms. In addition, this is the first of its time for the contributions of machining parameters (i.e., features) on surface roughness prediction by using interpretable analysis methods. The analysis results can provide a reference basis for subsequent experiments and studies. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate how two different polishing techniques affect the color stability, surface roughness, and changes in surface morphology of aged and coffee-stained bulk-fill resin composites. A total of 112 disc-shaped samples were prepared using Omnichroma Flow Bulk (OB), Charisma Bulk Flow One (CB), Estelite Bulk Fill Flow (EB), and Estelite Sigma Quick (control). Samples were divided into two subgroups (n = 16) and aged using thermocycling. A profilometer was used to measure the surface roughness (Ra) and a spectrophotometer was used for color stability (ΔE00). The EB group had the highest Ra values both before aging (disc: 0.23 ± 0.05, twist: 0.42 ± 0.05) and after aging (discs: 0.28 ± 0.04, twist: 0.46 ± 0.05). The OB group had the highest ΔE00 values before and after aging (discs: 3.06 ± 0.54, twist 3.05 ± 0.41) and the highest after coffee-staining (discs: 3.75 ± 0.70, twist: 3.91 ± 0.57). Re-polishing reduced the ΔE00 values in all materials but did not restore all to clinically acceptable levels. According to the results of this study, it can be concluded that the surface roughness and color stability of resin composites are notably influenced by the polishing technique, aging process, and coffee staining. Specimens that were polished using the multi-stage Super-Snap discs consistently exhibited smoother surfaces across all bulk-fill resin composites compared to those polished with the two-stage Diacomp plus Twist. [ABSTRACT FROM AUTHOR]

Nanofinishing of blind-hole cavities is important to produce high quality products without any surface irregularities. The commonly used methods such as grinding or honing are not efficient because of the uncontrolled forces and direct contact of the solid abrasive tool with the workpiece. Magnetorheological (MR) polishing process using smart fluid has proved its effectiveness in achieving the nano-finished surface. The existing tool design uses two different operations for nano-scale finishing of a blind-hole cavity, resulting into a higher production cost. In this present work, a novel tool that can vary its dimensions during finishing operation was developed for enhancing the surface finishing of blind-hole cavities. Distribution of magnetic fields within the entire tool and blind-hole cavity surface was found appropriate and also revealed that the tool surface has maximum magnetic field for stiffening the MR polishing fluid over its surface. After 90 minutes of finishing, it was concluded that the roughness (Ra) change on the blind-hole cavity were reduced by 75.12% (on inner vertical) and 74.21% (on inner bottom). [ABSTRACT FROM AUTHOR]

Having well-aligned and brightly white teeth are the two most preeminent components of an appleaing smile. During the 1980s, John Calamia introduced porcelain laminate veneers at New York University in the United States. Currently, Indirect restoration has become a common method for reconstructing damaged teeth. This involves using dental cement to attach the restoration to the tooth and fill the gap, preventing any displacement. The cementation process of ceramic laminates is a critical final step that requires careful handling. Cement thickness is one factor that influences the shear bond strength of luted veneers. Many factors govern cement thickness, one of them being the cement space provided either digitally or by the die spacer thickness and the number of coats applied. Success in this process has been attributed to a clinician's skill in proper case planning, selecting the appropriate ceramics, materials, and methods for cementation, conservative tooth preparation, impeccable finishing and polishing, and effective planning for ongoing restoration maintenance. [ABSTRACT FROM AUTHOR]

Surface roughness is a critical indicator to evaluate the quality of 4H-SiC grinding surfaces. Determining surface roughness experimentally is a time-consuming and laborious process, and developing a reliable model for predicting surface roughness is a key challenge in 4H-SiC grinding. However, the existing models for surface roughness in wafer rotational grinding fail to yield reasonable results because they do not adequately consider the processing parameters and material characteristics. In this study, we proposed a new analytical model for predicting surface roughness in 4H-SiC wafer rotational grinding, which comprehensively incorporates the grinding conditions and material characteristics of brittle substrate. This model derives and calculates the material's elastic recovery coefficient based on contact mechanics and elastic contact theory. Subsequently, we modified the grain depth-of-cut model by incorporating elastic recovery coefficient. Additionally, we analyze the distribution of the failure mode (ductile or brittle) on the surface of a material when the depth at which the material is cut instead follows a random distribution known as the Rayleigh distribution. To validate the accuracy of the established model, a series of grinding experiments are conducted using various grain depth-of-cut to produce 4H-SiC wafers with different surface roughness values. These results are then compared with those predicted by both this model and the traditional model. The findings demonstrate that the calculated data obtained from the proposed model exhibit better agreement with the measured data. This research addresses the need for an improved surface roughness model in 4H-SiC wafer rotational grinding. [ABSTRACT FROM AUTHOR]

In this study, the surface coating (modification) of micronized calcite (CaCO3, d50=135 μm) in a stirred media (bead) mill with stearic acid was investigated. As a result of 15 min grinding and 5 min coating experiments, a product with d50=2.15 μm and specific surface area of 3.21 m2 /cm³ was obtained. The activation rate of this final product as an indicator of coating rate was 97.7%. According to the optimum coating results, the stearic acid rate was determined as 1%, the modification time was 7.5 min, the ball load was 900 g and the stirring speed was 600 rpm. [ABSTRACT FROM AUTHOR]

This work reports the formation of a heterojunction composed of Tl2Ba2CaCu2O8 (Tl‐2212) and Bi2Se3 as the high critical temperature superconductor and topological insulator, respectively. The Bi2Se3 film is deposited on the Tl‐2212 by a chemical mechanical polishing process. Due to the rough surface of Tl‐2212, the treated Tl‐2212 is then subjected to post‐annealing at various temperatures. This temperature does not affect the formation of the interfacial layer at the heterojunction; however, an improved layered crystal structure of the Bi2Se3 film is observed at 500 °C. The in‐depth profile of the relative atomic concentration indicates the diffusion of Cu and Tl into the Bi2Se3 film with the Ba diffusion being closer to the interfacial layer. At 500 °C, Cu atoms are more actively diffused into the Bi2Se3 film, thus blocking Tl diffusion, and improving the layered crystal structure of the film. The density functional theory calculations reveal that the lowest formation energy of the Cu vacancy is when Bi2Se3 is in contact with Tl‐2212, which results in the diffusion of Cu atoms from Tl‐2212, thus transforming the interstitial Cu atoms into the film. These atoms have an n‐type doping effect and prefer intercalating at a vdW gap deep inside the layered Bi2Se3. [ABSTRACT FROM AUTHOR]

Silicon is essential to the production of integrated circuits and optical components. Grinding is a commonly used method of silicon surface machining, but it often leads to surface and subsurface damage. These damages need to be removed by subsequent processes, typically through polishing. The surface quality generated by grinding directly impacts the cost of polishing. To enhance the quality of the grinding surface and reduce the time and cost of polishing, a grind-polishing wheel with a different structure from the conventional diamond wheel was developed. This wheel utilized ultrafine zirconia with grit size of 200 nm as abrasives and nonwoven as substrate to support the abrasives. Furthermore, to optimize the wheel and achieve better grinding performance, various wheels with different abrasive mass fractions and elastic moduli were fabricated and grinding experiments were conducted. The surface integrity of processed silicon and the material removal rate (MRR) were used to compare the grinding performance of the various wheels. After optimization, the MRR of the grind-polishing wheel reaches its peak at 0.81 μm/min. The silicon wafer ground with the grind-polishing wheel exhibited a surface roughness S a of 0.51 nm and a subsurface damage depth of 74 nm, which is close to the effect of chemical mechanical polishing processing. Compared to conventional diamond grinding wheel (mesh size of #5000), the optimized grind-polishing wheel is better suited for semi-fine finishing and can significantly reduce the cost and time of polishing. [Display omitted] • Grind-polishing wheel with ultrafine abrasives and nonwoven structure is developed. • The newly developed wheel produces silicon wafer with high surface integrity. • Relationship between wheel characteristics and grinding performance is revealed. • High MRR is obtained by optimizing the characteristics of grind-polishing wheel. [ABSTRACT FROM AUTHOR]

Typically, the final process in the manufacture of molds is mechanical polishing, a process predominantly conducted manually. This is an important process step to improve the surface quality of the mold without affecting the geometry of the cavity. Currently, the European mold manufacturing industry faces two challenges for the polishing phase of manufacture. Firstly, economics when compared to global low-cost production areas. Secondly, the industry is starting to suffer the loss of skilled benchmen specialized in performing such operations. To address these two problems, robotic polishing has been investigated as an alternative or supplement to the conventional manual polishing process in the manufacturing of molds because of its high efficiency, improved reliability, and robustness. This paper presented a new methodology that allows robotic polishing to replace majority of manual polishing work for the manufacture of molds and achieves complete information integration with current CAD/CAM systems. Based on a number of experimental works, the types of features that are suitable for robotic polishing have been identified and a new robotic polishing feature classification has been proposed. A new polishing process planning has been developed to be integrated with current CAD/CAM systems, which includes a robotic polishing process knowledge database; a polishing process selection method; and a polishing process sequencing using genetic algorithm aiming to combine minimum polishing time and the specific constraints and rules for polishing process sequencing. Finally, a case study based on the proposed methods has been given, which demonstrates the proposed methodology is able to be implemented in the practical environment to allow robotic polishing to take majority of manual polishing workloads for mold manufacturing and achieve information integration with current CAD/CAM systems. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) is gaining more attention due to its capability to produce customized and complex geometries. However, one significant drawback of AM is the rough surface finish of the as-built parts, necessitating post-processing for achieving the desired surface quality that meets application requirements. Post-processing of complex geometries, such as parts with internal holes, lattice structures, and free-form surfaces, poses unique challenges compared to other components. This review classifies various post-processing methods employed for complex AM parts, presenting the experimental conditions for each treatment alongside the resulting improvement in surface roughness as a success criterion. The post-processing methods are categorized into four groups: electrochemical polishing (ECP), chemical polishing (CP), mechanical polishing, and hybrid methods. Notably, mechanical methods exhibit the highest roughness improvement at 69.9%, followed by ECP (59.9%), hybrid methods (47.4%), and CP (49.5%). Nevertheless, mechanical post-processing techniques are less frequently utilized for lattice parts, making chemical or electrochemical methods more promising alternatives. In summary, all four categories of post-processing methods can improve the internal surfaces quality of AM holes. While mechanical methods offer the most substantial roughness improvement overall, chemical and electrochemical methods show particular potential for addressing the challenges associated with complex geometries. [ABSTRACT FROM AUTHOR]

The thickness of the maximum undistorted chip (agmax) is a crucial component of the machining arguments and significantly affects the quality of the grind. For the purpose of investigating the impact of the agmax on the grinding removal properties of SiO2f/SiO2 composites, grinding experiments of SiO2f/SiO2 composites were conducted. The findings indicate that crack propagation, fiber cracking, matrix breaking, and interface debonding are the primary removal modes of SiO2f/SiO2 composites. Grinding force, surface roughness, and chip size all have a positive correlation with the maximum undeformed chip thickness. Surface brittle fracture brought on by SiO2 fiber microcrack results in little surface roughness. The surface quality degrades when bending fracture and compression fracture take place. Controlling the agmax can enhance the grinding surface quality of SiO2f/SiO2 composites. [ABSTRACT FROM AUTHOR]

For single crystal diamond (SCD) to gain practical use in technical applications including solid state electronics, thin (< $1 ~\mu \text{m}$), doped epitaxial SCD layers with very low (<1 nm) surface roughness are required. Conventional SCD chemical mechanical polishing (CMP) processes are insufficient to meet the requirements of such applications because the material removal rate (MRR) is often characterized inappropriately, and the material removal uniformity is seldom considered. In this study, chemical vapor deposition (CVD) growth of two lightly boron doped (p-) epilayers was performed on 3° misoriented (100) high pressure high temperature substrates of 4.5 x $4.5 mm^{2}$ area. A subsequent 8-hour oxidative CMP process utilizing potassium permanganate and a novel self-leveling holder design decreased the average surface roughness from 3.83 nm and 1.57 nm to 0.20 nm and 0.16 nm for the two samples, respectively. MRRs were determined by evaluating five circular wear monitor structures in each sample by atomic force microscopy before and after the CMP process. The average MRRs were found to be 38.6 nm/hr and 37.3 nm/hr for the two samples. The purpose of this study is to demonstrate a CMP process suitable for polishing thin SCD epilayers to meet the needs of solid-state electronics applications. [ABSTRACT FROM AUTHOR]

Chemical mechanical polishing/planarization (CMP) combines physical grinding and chemical reactions to planarize the wafer surface. The complex mechanism of CMP brings great challenges to the mechanism-based modeling process. The data-driven CMP modeling process is limited by insufficient datasets. At the same time, these two types of models generally have high computational complexity. In this paper, we introduce the group method of data handling (GMDH)-type polynomial network to build the CMP model to address the above challenges. We designed and manufactured the test chip using a 28nm process. The measurement data from the test chip shows that compared with the mechanism-based CMP model, the trained CMP model based on GMDH-type polynomial network has higher accuracy and lower computational complexity, with the average simulation speed being 115x faster. Experiments based on silicon data show that this modeling method has a small demand for data, and 20 randomly selected sets of data can meet the needs for modeling the current CMP process. [ABSTRACT FROM AUTHOR]

In the hybrid bonding process, the final stage of chemical mechanical polishing plays a critical role. It is essential to ensure that the copper surface is recessed slightly from the oxide surface. However, this recess can lead to the occurrence of interfacial voids between the bonded copper interfaces. To examine the effects of copper film thickness on bonding quality and bonding mechanisms in this study, artificial voids were intentionally introduced at the bonded interfaces at temperatures of 250 °C and 300 °C. The results revealed that as the thickness of the copper film increases, there is an increase in the bonding fraction and a decrease in the void fraction. The variations in void height with different copper film thicknesses were influenced by the bonding mechanism and bonding fraction. [ABSTRACT FROM AUTHOR]

CeO2 is widely used in the field of chemical–mechanical polishing for integrated circuits. Morphology, particle size, crystallinity, and Ce3+ concentration are crucial factors that affect polishing performance. In this study, we successfully synthesized two novel triangular CeO2 abrasives with similar particle sizes (600 nm) but different morphologies and Ce3+ concentrations using a microwave-assisted hydrothermal method with high-concentration raw materials, and no surfactants or template agents were added. It is generally believed that CeO2 with a higher Ce3+ concentration leads to better polishing performance. However, the results of polishing indicate that CeO2 synthesized at 200 °C, despite its lower Ce3+ concentration, demonstrates outstanding polishing performance, achieving a polishing rate of 324 nm/min, and the Sa of Si wafers decreased by 3.6% after polishing. This suggests that, under similar particle size conditions, the morphology of CeO2 plays a dominant role in the mechanical effects during the polishing process. Additionally, compared to commercial polishing slurries, the synthesized samples demonstrated better polishing performance. This indicates that, in CMP, the pursuit of smaller spherical abrasives may not be necessary. Instead, the appropriate shape and particle size can better balance the material removal rate and surface roughness. [ABSTRACT FROM AUTHOR]

Elastic spherical polishing tools effectively conform to the polishing surface and exhibit high efficiency in the removal of materials, so they are extensively used in the sub-aperture polishing stages of optical components. However, their processing is often accompanied by significant mid-spatial frequency (MSF) errors, which critically degrade the performance of optical systems. To suppress the MSF errors generated during polishing with spherical tools, this study investigates the influence factor of MSF errors during the polishing process through an analysis of the convolution effect in material removal. A material removal profile model is established, and a uniform removal simulation is conducted to assess the influence of different shape material removal profiles on MSF errors. Simulation and experimental results show that a Gaussian-like shape material removal profile is more effective in suppressing the MSF errors during polishing compared to the "W" and trapezoidal shape material removal profiles. In addition, based on the characteristics of the RMS decreasing in a serrated trend with the decrease in path spacing, a path spacing optimization method considering the polishing efficiency is proposed to improve the polishing efficiency while controlling the MSF errors, and the effectiveness of the path spacing optimization method is verified by comparing the MSF error at the maximum theoretical path spacing and the path spacing that is less than this. Finally, the path spacing optimization method is used to polish single-crystal silicon to further illustrate its practicality. [ABSTRACT FROM AUTHOR]

The use of surfactants is crucial in the chemical–mechanical polishing fluid system for silicon wafers. This paper examines the impact of the functional group structure of polyoxyethylene-based nonionic surfactants and the variation in the polyoxyethylene (EO) addition number on the polishing performance of monocrystalline silicon wafers, to achieve the appropriate material removal rate and surface quality. The results demonstrated that the straight-chain structure of fatty alcohol polyoxyethylene ether (AEO-9) exhibited superior performance in wafer polishing compared to octylphenol polyoxyethylene ether (OP-9) and isoprenol polyoxyethylene ether (TPEG) and polyethylene glycol (PEG). By varying the number of EO additions of AEO-type surfactants, this study demonstrated that the polishing performance of monocrystalline silicon wafers was affected by the number of EO additions. The best polishing effect was achieved when the number of EO additions was nine. The mechanism of the role of polyoxyethylene-type nonionic surfactants in silicon wafer polishing was derived through polishing experiments, the contact angle, abrasive particle size analysis, zeta potential measurement, XPS, and other means of characterization. [ABSTRACT FROM AUTHOR]

During the polishing process of complex curved PMMA parts, the polishing force is an important factor affecting the surface quality and optical performance. In this paper, a force-controlled polishing device integrated into a machining center to maintain the polishing force is investigated. In order to achieve the real-time active control of the polishing force, the linear voice coil motor and force sensors are used for motion and measurement. A compact structure was designed to couple the linear motion of the voice coil motor with the rotation for polishing. The force-controlled polishing system with a high real-time hardware architecture was developed to perform complex curved polishing path movement with precise force control. Next, the polishing force between the device and the workpiece was analyzed to obtain the mathematical model of the device. Considering the impact during the approaching phase of polishing, a fuzzy PI controller was proposed to reduce the overshoot and response time. To implement the control method, the controller model was established on Simulink and the control system was developed based on TwinCAT 3 software with real-time computing capability. Finally, a polishing experiment involving a complex curved PMMA part was conducted by a force-controlled polishing device integrated into a five-axis machining center. The results show that the device can effectively maintain the polishing force to improve surface quality and optical performance. [ABSTRACT FROM AUTHOR]

Polyetheretherketone is a high-performance thermoplastic polymer that can be used in 3D printing by fused deposition modeling, and is a promising material for dental applications. Some printing parameters are sensitive and can influence the properties of the printed object. Thus, this work aims to evaluate the influence of the print layer thickness on the surface roughness of polyetheretherketone before and after polishing and to verify the effectiveness of the polishing method used, as well as to compare it with the results obtained using polymethyl methacrylate as the control group. Specimens with different impression layer thicknesses were printed with polyetheretherketone (Group A—0.1 mm and Group B—0.3 mm). Additionally, a control group with polymethyl methacrylate specimens was milled. Roughness evaluation was conducted using a contact profilometer after the specimens had been printed (before polishing). Then, silicon carbide sandpaper was used to polish the surface, and the roughness was reassessed. Differences were observed between specimens regarding the print layer thickness and the roughness, with the 0.3 mm layer thickness showing the lowest roughness values. The results of this pilot study suggest that the surface roughness of fused deposition modeling printed polyetheretherketone is influenced by print layer thickness, with the lowest roughness seen at a thickness of 0.3 mm. [ABSTRACT FROM AUTHOR]

The purpose of this study was to clarify whether the wood grinding model -- based on an energy balance for the grinding zone -- would improve understanding of wood grinding for pulp. This study relied on previously obtained data by the Finnish Pulp and Paper Research Institute. The frictional coefficient (Pc/Pt) computed and the power-specific groundwood production (Ġw/Pt) were important x- and y- variables, respectively. Fresh spruce wood samples were ground by application of a laboratory grinder, where the stone surface speeds were 30, 15 and 7 m/s, respectively. The power-specific productivities of high- and medium-speed grindings followed one and the same mechanism, since both speeds led to a productivity of 0.99 [(kg/h)/kW]; the low-speed grinding, however, led to a level of 0.66 [(kg/h)/kW] at frictional coefficients closest to 100 mW/kW. The rate of formation of coarse rejects was -- at the same frictional coefficient as before -- 15.0, 4.3 and 2.3 mg/s for high-, medium- and low-speed grindings, respectively. However, the rate of fines formation determined by McNett apparatus was about ten times higher than that of formation of coarse rejects: 123.0, 42.2 and 23.7 mg/s, respectively. The fines-to-shives ratio (determined by a Somerville shive analyser) was assumed to indicate fiberisation for high-, medium- and low-speed grindings, and the true data, most close to 100 mW/kW, were 56.0, 55.9 and 36.1 units of fines-to-shives, respectively. The curves followed the same trend, but on slightly different levels. As for the important sheet properties, the tensile strengths of high-, medium- and low-speed grindings were low, medium and high, respectively: 37.1, 46.9 and 56.2 Nm/g. The light scattering coefficients of high-, medium- and lowspeed grindings were low, medium and high, respectively, or as data being most close to 100 mW/kW: 59.2, 66.0 and 67.5 m2/kg, respectively. Some general conclusions may be drawn from these results. To achieve the best groundwood productivity, the frictional coefficient should be kept on a level close to 100 mW/kW. Generally speaking, it seems that high- and medium-speed grindings appeared to act as following the same mechanism as far as the productivity was concerned, but the rates of shives and fines formation did not follow such a pattern. The groundwood sheets showed lower tensile strength in high-speed grinding than in medium-speed grinding, while the light scattering coefficient was much lower for the high-speed grinding than for the medium-speed grinding. Because of its low productivity, the low-speed grinding does not seem to be useful, although high tensile strength and high light scattering of the sheets would plead for it. [ABSTRACT FROM AUTHOR]

To improve the processing performance of vitrified bonded diamond fixed-abrasive lapping plates for processing sapphire substrates, a free-abrasive was added to the lapping slurry to enhance the self-dressing ability of the lapping plate to achieve efficient and high-quality processing of sapphire substrates. The processing effectiveness and mechanism of a free-abrasive assisted fixed-abrasive lapping plates (FAAFALP) lapping process for sapphire substrates were analysed and revealed via a single-factor experiment. To optimise the lapping process of the FAAFALP of sapphire substrates with good overall performance (high material removal rate (MRR), minor surface roughness (Ra) and big lapping plate wear ratio (η)), the effects and the optimal parameters combination of the lapping pressure, lapping speed and free-abrasive concentration on MRR, Ra and η of lapping-processed sapphire substrates were investigated using orthogonal experiments. Furthermore, the experimental results were combined with process parameters to establish a regression model. The multi-evaluation index optimisation problem was transformed into a single-index optimisation problem via the grey relational analysis (GRA) to evaluate each parameter's performance comprehensively. The results revealed that an MRR increased by 22.2 % to 2.48 μm/min, the smallest surface roughness Ra of 0.141 μm, and the lapping plate wear ratio η relatively increased to 14.88 was obtained when a free-abrasive of SiO 2 with a particle size of 14 μm was added into lapping slurry. Compared with no free-abrasive lapping process, free-abrasive can significantly improve the lapping plate's self-dressing ability and enhance the sapphire substrates' processing effect. The lapping speed, lapping pressure and free-abrasive concentration had different influence degrees on MRR, Ra and η. The established regression equations predicted the response values of MRR, Ra and η to be 99.87 %, 99.06 % and 98.59 %, respectively, and the relative errors between the predicted and actual measured values were <12 %. With increased lapping speed, MRR initially decreased but subsequently increased, and Ra and η gradually decreased. MRR and η continuously increased with increased lapping pressure, whereas Ra decreased. With increased free-abrasive concentration, MRR, Ra and η initially increased but subsequently decreased. Comparing the optimised results obtained by intuitive analysis, the parameters optimised via the GRA were used to obtain sapphire substrates lapping with an MRR of 3.81 μm/min, Ra of 0.133 μm and η of 20.4, and the overall lapping performance was better 42.92 %, 102.90 % and 43.60 % than that of intuitive analysis for MRR, Ra and η. Therefore, combining orthogonal experiments and GRA can provide new ideas for optimising the FAAFALP lapping process for sapphire substrates. • The processing effectiveness and mechanism for sapphire substrates were analysed and revealed. • Effects of process parameters for sapphire in lapping on MRR, Ra and lapping plate wear ratio were studied. • A regression model combined with experimental results and process parameters was established. • Grey relational analysis was used to obtain parameters with good lapping performance. [ABSTRACT FROM AUTHOR]

As a novel surface treatment technology, in-situ laser polishing aims to improve surface finish of 3D printed parts, while laying the foundation for the integrated processing of 3D printing and laser polishing. However, the polishing process will introduce a few new surface structures (undercuts, step structures, ripples, etc.), which will affect the surface roughness. In this work, the surface roughness and surface structure after high power and low power polishing were compared respectively through experiments. In addition, a 2D transient numerical model was developed to explore the forming mechanism of different structures. The evolution of temperature field, velocity field and freedom surface of melting pool under different parameters were analyzed by the model. The results showed that the solidification induced surface structure with large roughness was generated after high power polishing. During its formation, the thermocapillary force was dominant and drove the tangential flow of fluid. While, low power polishing resulted in ripple structure with small roughness. The emergence of this structure was primarily due to the capillary force as the leading force in the melting pool flow process, which drove the normal flow of the melt, thus eliminating the large surface curvature. Furthermore, the width of the melting pool in the simulation was compared with the width of the single scanning track, and they were in good agreement. Finally, by adjusting the test strategy, it was found that the surface roughness could reach the lowest (0.88 ± 0.06 μm) only when the two structures coexisted. • High power polishing produces solidification induced surface structure with large roughness. • Low power polishing results in surface ripples with low roughness. • High power polishing is SOM mechanism, and tangential thermocapillary force is dominant. • Low power polishing is SSM mechanism, and normal capillary force predominates. • The simulation values agree well with experimental values, and the errors are all within 10 %. [ABSTRACT FROM AUTHOR]

Previously, we developed an abrasive-free polishing technique called catalyst-referred etching (CARE) for inorganic materials. In this method, the topmost site of the workpiece surface is preferentially removed via an indirect hydrolysis reaction promoted by a metal catalyst. In this study, we proposed applying the CARE method to polymer material polishing and demonstrated the polishing characteristics. Using the CARE method, polycarbonate, which has an easy cleavage of ester bond via hydrolysis, was polished, resulting in the smoothness of the surface roughness below 1.0 nm. Based on the surface observations, the removal mechanism was estimated as follows. Molecule chains are entangled to form clusters constituting the polymer surface and help determine the surface roughness. In the CARE method, the top of this cluster was selectively removed, thus creating a smooth surface. Polymers with C–C bonds, such as polymethyl methacrylate and fluorinated ethylene propylene, were also smoothed using the CARE method. These results indicate that the CARE method is highly effective in polishing polymer materials. [ABSTRACT FROM AUTHOR]

The most common method of post-weld finishing is grinding with an abrasive tool. This finishing method leads to the occurrence of faults on the treated surface: locations missed or hardened twice, structural notches and stretching residual stress in the surface layer. The faults mentioned lead to the creation and development of ordinary as well as fatigue cracks, seizing or other damage. In addition, grinding is a process that often involves manual labour, which significantly increases the time required for finishing the procedure. Moreover, it is impossible to automate this process. Also, grinding is a process that is damaging for both people and the environment. In contrast to grinding and other processes of post-weld surface finishing, the innovative method, which is the subject of this article, does not have the faults and inconveniences of the previously mentioned techniques. The post-weld surface finishing method by moving of the innovative multi-edge cutting tool along the weld bead is presented in this article. In this method, machining allowance is treated as the weld bead height, which is flush-removed with the base material in one step during one pass of the cutting tool. The adjacent teeth height of changing and increasing according to the direction of feed and the difference in height between the first and last teeth are equal to the weld bead height. The number of cutting teeth necessary to flush-finish the weld bead with the base metal surface depends on the difference in the first and last teeth height and how it is divided. The tooth length is greater than half of the distance between the adjacent cutting teeth, which enables finishing the heterogeneous post-weld surface with many defects and increased hardness. The innovative method is characterised by short machining time of the weld bead and provides an accurate, efficient and economical process. [ABSTRACT FROM AUTHOR]

In advanced integrated circuit manufacturing, the quality of chemical mechanical polishing (CMP) is a key factor affecting chip performance and yield. Designers need to use CMP simulation tools to locate and analyze the defects in the layout after the CMP process. However, the advancement of process nodes and the increase in data volume presents a great challenge to the speed of graphical display of CMP simulation data. To solve this issue, we propose a solution that uses multi-threading technology to optimize both data reading and drawing. In the process of data reading, we employ OpenMP and memory mapping (Mmap) technology to achieve parallel reading of file segmentation and propose a fast-string conversion algorithm based on the properties of simulation data. In the process of data drawing, we propose an adaptive downsampling method for data graphical display that combines multi-threading and double buffering technology to enable the parallel drawing of layouts. The effectiveness of this method is verified by testing CMP simulation data of various scales. Compared to traditional methods, this approach improves reading efficiency by over 8 times and drawing efficiency by more than 10 times. Furthermore, it enhances the smoothness of interaction with the CMP simulation tool. [ABSTRACT FROM AUTHOR]

The number and variety of paints and coating systems in the automotive industry have increased in recent years. However, the basic requirement for the quality of the paints still depends on the surfaces on which they are applied. This applies not only to the large body parts but also to all components that are integrated. There are many surface treatment processes and techniques that are used as an additional process step, such as pickling for a chemical surface treatment or blasting for a mechanical surface treatment. The present work investigates a method for optimizing the surface before painting, using the membrane cup of the ultrasonic sensor as an example for AlMgSi1 alloy, without implementing additional process steps. First, all process steps influencing the surface quality for the production of a membrane cup were considered for optimization. Then, based on a backward process chain analysis, vibratory grinding for deburring of the membrane cup was determined as the process step to be optimized. For the optimization of the vibratory grinding, experiments with two different grindstones were performed. For the characterization of the surface quality, the roughness parameters Rz and Ra were measured with a confocal laser scanning microscope and analyzed in order to determine the optimal process conditions. The experiments showed that the surface roughness can be significantly improved using dedicated process parameters and taking into account the geometry of the vibratory grinding stones. Moreover, different surface qualities can be achieved at different areas on the workpiece, this new approach provides a solution for surface optimization in various areas of the workpiece without additional process steps and costs. [ABSTRACT FROM AUTHOR]

Protonic ceramic fuel/electrolysis cells (PCFCs/PCECs) show great potential for the efficient and reversible conversion of chemical and electrical energy. The electrolyte and oxygen electrode interface in PCFCs/PCECs is particularly crucial for achieving optimal performance. In this work, Ba evaporation and Y enrichment phenomena are investigated on the surface of a BaCe 0.7 Zr 0.1 Y 0.2 O 3-δ electrolyte during high-temperature sintering. Furthermore, an interfacial engineering strategy is proposed by removing the non-stoichiometric perovskite surface layer via a facile polishing process to enable a comparative analysis of the detrimental effects of the undesired layer on the cell performance. Polishing the electrolyte leads to a remarkable ∼50 % enhancement in PCFC performance and ∼120 % enhancement in PCEC performance at 650 °C. Electrochemical impedance spectroscopy coupled with distribution of relaxation time analysis reveals that the improved performance of the polished cell can be attributed to reductions in both the ohmic and polarization losses, with the latter primarily influenced by the facilitated oxygen electrode reactions. This interfacial engineering approach restores the high proton conductivity at the electrolyte surface and strengthens the physical and chemical adhesion between the electrolyte and the oxygen electrode. Our findings shed light on the existing challenges at the electrolyte-electrode interface and underscore the significance of interfacial engineering in enhancing PCFC/PCEC performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Thermal barrier coatings (TBCs) can significantly improve the turbine blades' high-temperature tolerance in turbine engines, the high surface roughness for the as-sprayed coating can have an adverse effect on engine performance. In order to reduce the roughness of the blade surface coating, for aero-engines and gas turbines blades, the industry's traditional method uses abrasive belts to polish the coating by manual pickup or robot clamping. The aero-engine blade studied in this paper, itself small size, the surface exhibits significant variations in curvature, the use of abrasive belt polishing method, difficult to control the polishing effect. For the current use of the model surface-based grid point division method, due to casting errors, the generated polishing path, and the actual blade, there is part of the accuracy error. To solve these problems, this paper proposes a polishing path planning method for surface TBCs applied to small blades of aero-engine turbines. By pre-processing and point cloud slicing the 3D point cloud of the blades, a polishing path is created using point cloud discretization and the B-spline curve fitting approach, guaranteeing that the accuracy error is within 0.1 mm. Simulation and experimental verification show that the method can reduce the surface roughness of blade coating to below Ra0.7 μm, which can meet the requirements and accuracy of polishing processing, while ensuring the effective thickness of the coating. [ABSTRACT FROM AUTHOR]

Adornments such as pendants, beads, and other perforated objects are an important finds category in Upper Paleolithic sites. Raw materials, production technology, and use-wear can tell us much about the objects and technocultural context of their carriers. Excavations from 2005–2015 at the Gravettian (Pavlovian) site of Krems-Wachtberg provided 110 objects which can be interpreted as adornments. They consist of mammoth ivory beads and pins, perforated canine teeth and molluscs, and fossil Serpulidae. More than half of these objects were found in the context of a double burial of infants. A recently conducted investigation describes all adornments and places them into a chronological and technological context. Analyses of all objects in this study were carried out using a Keyence VHX 7000 stereomicroscope. Micro photos were produced for all objects and allowed a wide range of measurements which would otherwise not have been possible to make considering the objects’ poor state of preservation. The produced micro photos will allow for additional non-destructive morphological analyses in the future. Information concerning the preservation of the raw material, use-wear, traces of production, method of perforation, fire exposure, and residues were collected in a database. The 53 mammoth ivory beads found in the double burial in particular allowed not only for reconstructing a chaîne opératoire for the manufacture, but provided interesting information regarding the objects’ lifecycle. Polishing on the bridges of some of the pendants’ perforations, presumably caused by a thread, and the location of the polished areas in relation to their positions show that some beads had already been worn before being deposited in the burial. This suggests that they were not explicitly made for the infants’ burial as previously suggested. [ABSTRACT FROM AUTHOR]

In the electropolishing process, the polishing quality of the metal surface varies according to the contamination of the electrolyte. In this study, the electrolyte was evaluated according to the usage time, and the effect of each factor on electropolishing was investigated. As the electrolyte is contaminated, the concentration of metal ions in the electrolyte increases and the ion conductivity decreases. In addition, the pH and specific gravity of the electrolyte increase due to the metal sludge formed as the metal ion concentration increases. When the electrolyte usage time was more than 5 days, many scratches remained on the surface of 316L stainless steel, and relatively high surface roughness was measured. The surface roughness improvement rate compared to the initial specimen was 30% for the unused electrolyte, 26% on the 3rd day, 19% on the 5th day, and 17.5% on the 13th day. Since the low current density due to electrolyte contamination causes a decrease in polishing efficiency, initial scratches on the metal surface still exist on the polished surface. Therefore, it is necessary to manage the electrolyte to maintain the quality of electropolishing. [ABSTRACT FROM AUTHOR]

In the county of Pedra Lavrada – PB, various mineral occurrences of pegmatite are observed with prominence at Alto Dois Irmãos – PB, where quartz, feldspar and mica are mined. The understanding of mineral constituents is fundamental to define their industrial employment and to implement improvements in the beneficiation process. The proposal of this research is the detailed characterization and proof of that part of the ore (quartz) considered waste, presenting low poisoning (Fe2 O3 ) and high silica (SiO2) content, to enable its industrial use. Besides that, to minimize the environmental impact through the reuse of this waste, and to determine the correct utilization of the milling equipment. For the pegmatite characterization, done were density determination tests, mineralogical identification by X-ray diffraction (XRD), chemical analysis by fluorescents X-rays and morphological analysis by scanning electron microscopy (SEM/EDS). Then tests were done for the Work Index (WI) calculous and consequently the empirical determination of the dimensions (LxD) of the pebble mill. The sterile presented a medium density of 2.66g/cm³, majority chemical composition of silicon and oxygen and quartz as the main mineralogical stage, indicating that this material has high purity. The. The Work Index (WI) was 15.9 kwh/t showing that this material can be considered resistant to breaking in the grinding process. The necessary energy to the milling was defined in 11.52 kwh/st, that corresponds to 57.28 HP. This power allowed the mill selection with diammeter and length of 1.83m, that provides the production maximization and the energy saving. [ABSTRACT FROM AUTHOR]

In order to study the effect of vibration direction on vibration-assisted fixed abrasive polishing and explore the influence rule of vibration direction on material removal rate and workpiece surface quality, a single abrasive particle vibration-assisted fixed abrasive polishing model was established to study the effect of axial and radial vibration on workpiece profile depth, surface morphology, etc. And the experiments of vibration-assisted fixed abrasive polishing in different vibration directions were carried out. The results show that axial vibration auxiliary polishing can greatly advance the processing efficiency, and improve the workpiece material removal rate by 27.6%; radial vibration auxiliary polishing can achieve better surface quality, and reduces the surface roughness by 59.8%. [ABSTRACT FROM AUTHOR]

The existence of hazards and risks in businesses is inevitable, specifically, in the construction industry. The research is qualitative by nature which aimed the identification and investigation of the actual hazards and risks in the workplace as experienced by the select construction workers as main participants in the research. A total of eleven (11) constructions workers were utilized in the research and selected by way of purposive sampling. During the focus discussions, participants are divided into three groups. Among others, results revealed the following construction-related hazards: Scattered Broken Tiles, Unstable Scaffolding, Scattered Nails, Insufficient Lightning, Exposed Extension Wire and Chiselling and Grinding, No Insulation and Physical Transport of Heavy materials. The research further investigated the level of risks in the identified hazard using the probability and severity matrix. At average, the identified risks obtained a high level of probability while severity at average is to medium or moderate only. Occupational Construction and Health and Safety Program was developed based on the results of this research. [ABSTRACT FROM AUTHOR]

Polishing torque holds significance in monitoring the chemical mechanical polishing (CMP) process due to its close correlation with material removal. This study introduces a new model-based technique for estimating the material removal rate (MRR) using in-process data from CMP machines. The proposed method employs either the sequential least squares method or Kalman filter for real-time state estimation. Real-time estimation of MRR enables material removal control without relying on conventional endpoint detection (EDP) technologies. The accuracy of the proposed approach is validated through oxide CMP experiments, demonstrating precise estimation of the center-slowed MRR profile towards the end of the pad life. [ABSTRACT FROM AUTHOR]

Şarhöyük/Dorylaion (Dorylaeum) is one of the largest mounds in central Anatolia and boasts a stratigraphical sequence that spans from the Late Chalcolithic period to the end of the 12th century AD. This paper focuses on a particular set of discoveries made at Şarhöyük, namely the Olynthus millstones, or the hopper-rubbers, which are generally considered as an important development stage from basic grinding mills to complex grinding techniques. Most of the millstones discovered were found in the Hellenistic layers, either in situ or in secondary contexts. With the exception of the mill with hand grips, all other samples that can be classified based on a certain typology belong to the Olynthus Mills group with Vertical Holes for Pivot, commonly referred to as Frankel’s Type II.4 or Bombardieri’s Type IIID.3e. However, it is plausible to suggest subtypes within this group. The aim of this study is to analyse a specific ‘eastern type’ Olynthus mill and the timeframe of its usage based on archaeological data from Şarhöyük/Dorylaion and its surrounding region. [ABSTRACT FROM AUTHOR]

Six different composites were used in the study. From each material, 40 cylinder-shaped samples were made. All samples were polymerized and polished using three different methods. To evaluate surface roughness a confocal laser microscope was used, and microhardness was determined using a universal Vickers hardness tester. The data were analysed using the one-way ANOVA test at a significance level of 0.05 for both tests. The smoothest surfaces in all groups of composites were obtained for control samples. Also in all groups of composite samples no statistically significant differences were found between the Sof-Lex and Enhance+PoGo. The measurement of surface roughness obtained for the Kenda system showed significantly lower values than for the other two methods. The surfaces of the control samples showed statistically significantly lower microhardness values compared to all polishing systems for all six tested resin composites, additionally no statistically significant differences were found between all finishing and polishing methods. Regardless of the finishing and polishing method used, the lowest microhardness values among microhybrid materials were found for Charisma Flow, while among nanohybrid materials the lowest values were obtained for Herculite HRV Ultra. Finishing and polishing increases the microhardness of microhybrid and nanohybrid composite resin. The use of Kenda three step polishing system resulted in smoother surface for all tested composite materials compared to the Sof-Lex and Enhance+PoGo systems, while the finishing and polishing method had little effect on the microhardness of the surface. [ABSTRACT FROM AUTHOR]

Background: The references of gnashing the teeth historically were described in negative annotations. In many cultures the gnashing of teeth has been associated with suffering, physical pain, madness and possession. Bruxism is mentioned in the Bible in several verses. Bruxism is said to have multiple causes. They include central factors, psychosocial factors and peripheral factors. The Bruxism Association underlined several factors of causes of bruxism: 1) sleep disorders, 2) Lifestyle factors 3) Stress, anxiety and other psychological components. Therefore, the treatment is multifaceted. Treatment aims to find and remove the causes of bruxism, change the behavior that causes bruxism and repair the damage that often causes Aim: The aim of the study was systematical literature revision about historical view of bruxism. Methods: The literature review was performed using the following databases to identify relevant scientific studies. The language was restricted to English. The year of publication was limited over the last 6 Years. Results: More than 60 articles were found. 29 most relevant publications were chosen. Before 2013 there is no consensus about the definition and diagnostic grading of bruxism. A written consensus discussion was held among an international group of bruxism experts in 2013 as to formulate a definition of bruxism and to suggest a grading system for the operational-ization. Conclusion: Bruxism is a common parafunctional habit, occurring in male, female and children, in any ages. The management of bruxism should focus to prevent progression of dental wear, reduce teeth grinding sounds, and improve muscle discomfort and TMJ dysfunction. [ABSTRACT FROM AUTHOR]

A diamond gel polishing disk with self-sharpening ability is proposed to solve the problem of glazing phenomenon in the gel polishing disks. Aluminum nitride (AlN) powder with silica sol film coating (A/S powder) is added to the polishing disk, and a specific solution is used to dissolve the A/S powder during polishing, forming a pore structure on the polishing disk. To realize the self-sharpening process, the dissolution property of the A/S powder is analyzed. The effect of A/S powder content on the friction and wear performance and the polishing performance of 4H-SiC wafers are investigated. Results showed that the friction coefficient of the polishing disk with 9 wt% A/S powder content is the most stable. The surface roughness Ra of 2.25 nm can be achieved, and there is no obvious glazing phenomenon on the polishing disk after polishing. The surface roughness of the 4H-SiC wafer is reduced by 38.8% compared with that of the polishing disk with no A/S powder addition after rough polishing, and the 4H-SiC wafer then obtained a damage-free surface with a Ra less than 0.4 nm after fine polishing by chemical mechanical polishing (CMP). [ABSTRACT FROM AUTHOR]

To liberate copper from malachite, the ore has to be reduced to appropriate size using comminution processes. Ball mills are commonly used to obtain fine particles in grinding circuits. Population balance equations can be used to model grinding kinetics in a ball mill. The aim of this study was to understand the mineralogical characteristics of malachite copper ore and identify its grinding kinetics. To achieve this, chemical analysis and petrographic studies on thin slides were carried out. Additionally, grinding tests were carried out in a ball mill using five mono-sized fractions. Short grinding cycles of 0.5 minutes were used to calculate breakage distribution functions. Longer grinding cycles up to 30 mis were used to determine specific breakage rates. The experimental results were fitted into population balance models to obtain breakage parameters that characterize the material. The parameters were used to predict particle distributions. The malachite bearing copper was found to exists among other minerals. The average concentration of copper was found to be 4.7%. The specific rate of breakage increased as particle size increased to a maximum value at particle size of 2 mm. The parameters of grinding kinetics computed parameters were applied in prediction of particle size distribution. The particle distribution produced a high degree of agreement between the simulated and experimental results. The parameters can be used in the design of ore flowsheets for processing malachite ore. [ABSTRACT FROM AUTHOR]