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Graphene/stainless steel (SUS) structures have received attention as an approach to enhancing the performance of SUS in various applications, such as energy storage and electrochemical devices. Despite many studies, the synthesis of graphene nanostructures with controllable growth orientation on SUS remains challenging. The present work demonstrates the selective synthesis of monolayer to bilayer graphene and vertical graphene (i.e., carbon nanowalls) on SUS by plasma enhanced chemical vapor deposition and also explains the associated growth mechanisms. This study indicates that the graphene nucleation density can be tuned by varying the growth temperature and CH4/H2 ratio during synthesis. It is also evident that graphene growth occurs within a mixed phase of γ-Fe and Fe3C at high temperatures, and a high carbon supply of above 900 °C triggers the transition of growth orientation from planar to vertical. [ABSTRACT FROM AUTHOR]

This paper proposes a piezoelectric energy harvester that concentrates force on the piezoelectric element by parallel springs. When vibrating, the force exerted by the mass is released at three equal points on the surface of the brass substrate through three parallel springs. This concentrated release of energy through the spring amplification effect facilitates large deformation of the piezoelectric ceramic sheet, resulting in a higher charge output. The results show that under the combined action of a 14 g annular hollow mass and a 0.3 mm wire diameter stainless steel spring, the energy harvester based on the lead zirconate titanate ceramic exhibited an outstanding output power of 1.0–32.1 mW at a low resonance frequency with acceleration amplitudes of 0.5–3 g (1 g = 9.8 m/s2). More importantly, to match the vibration frequency of the actual environment, this paper optimized the structure of the harvester and proposed that the harvester can be designed by selecting the weight of the mass block, the parameters and number of springs, and the shape of the brass substrate. The energy harvester designed in this study is expected to capture energy from low-frequency natural environments and exhibit outstanding output performance, which can provide guidelines for future efforts in this direction. [ABSTRACT FROM AUTHOR]

Active thermography using pulsed heating is a fast and reliable method for detecting flaws in composite and metallic materials. This paper analyzes the temperature decay that occurs immediately after flash heating the front surface of stainless steel specimens as a function of time, based on a novel application of the equivalent circuit approach (ECA). The temperature decay from the front surface is equated to the discharge of a capacitor. The ECA is based on the charging (temperature rise due to flash heating) of a capacitor, followed by its discharge (temperature decay) through a series of resistors (which depends on the conductivity of the material) and capacitance (which depends on the thermal capacitance of the layers) through which the heat is dissipated. The proposed approach analyzes the sequences of temperature data obtained at each pixel location during cooling from a step wedge and a specimen with multiple flat-bottom holes. Time constant maps derived from the analysis are used to ascertain the thickness of the step wedge, detect the flaws, and evaluate the remnant thickness of the flaws. A correlation has been established between the thickness and the time constants. The above approach has been used to estimate the diameter of the flat-bottom holes. [ABSTRACT FROM AUTHOR]

Additive manufacturing has the potential to repair damaged parts, but the performance of additive materials under high strain rate loading is still uncertain—especially with the added complexity of an interface with an existing wrought material. In this work, 304L stainless steel samples were intentionally damaged and then repaired with wire-fed laser additive manufacturing. The samples were subjected to shock loading to generate incipient spall. Velocimetry and post-mortem metallography results show that when the additive repair process parameters are optimized to reduce porosity and match the equation of state of the original material, the influence of the repair region on the shock propagation is negligible. The free-surface velocity profile and internal damage morphology of the repaired sample are shown to be practically identical to the pristine material. [ABSTRACT FROM AUTHOR]

Properties of fragmentation from an explosively driven 316L stainless steel spherical shell section fabricated by a laser powder bed additive manufacturing process with minimal surface finishing are investigated. This shell is driven by an insensitive high explosive, resulting in high strain rate deformation (>8 × 103 s−1) and failure of the stainless steel. Photonic Doppler velocimetry measures the expansion rate; dynamic radiography and high-speed imaging capture the fracture behavior of the stainless steel. The fracture response of the additively manufactured stainless steel shell is compared to published experimental results on additively manufactured 316L stainless steel and conventionally manufactured wrought 316L and 304 stainless steel shell fragmentation. Despite preferred crack orientation, suggesting the influence of surface grooves on fracture time, fragment size is identical to that measured in a similar experiment on wrought 304 stainless steel. Further analysis indicates that the 316L additively manufactured stainless steel shell exhibits comparable spall strength and fragmentation toughness to conventionally manufactured stainless steel yet lower failure strain due to surface stress concentrations. [ABSTRACT FROM AUTHOR]

Laser-powder bed fusion additive manufacturing (LPBF-AM) of metals is rapidly becoming one of the most important materials processing pathways for next-generation metallic parts and components in a number of important applications. However, the large parametric space that characterizes laser-based LPBF-AM makes it challenging to understand what are the variables controlling the microstructural and mechanical property outcomes. Sensitivity studies based on direct LPBF-AM processing are costly and lengthy to conduct, and are subjected to the specifications and variability of each printer. Here we develop a fast-throughput numerical approach that simulates the LPBF-AM process using a cellular automaton model of dynamic solidification and grain growth. This is accompanied by a polycrystal plasticity model that captures grain boundary strengthening due to complex grain geometry and furnishes the stress-strain curves of the resulting microstructures. Our approach connects the processing stage with the mechanical testing stage, thus capturing the effect of processing variables such as the laser power, laser spot size, scan speed, and hatch width on the yield strength and tangent moduli of the processed materials. When applied to pure Cu and stainless 316L steel, we find that laser power and scan speed have the strongest influence on grain size in each material, respectively.

High-efficiency and low-cost electrocatalysts play an important role in clean hydrogen production through electrocatalytic water decomposition. Therefore, it is of great significance to develop an effective method to retrieve rusty stainless steel and facilitate the slow oxygen evolution reaction (OER) for an environment-friendly and sustainable society. Herein, we developed a method to synthesize Fe–Ni bimetallic hydroxide (RSS-LDH) using chloride ions to corrode rusty stainless steel, which can be used as an efficient and cheap catalyst for OER and hydrogen evolution reaction (HER). We found that RSS-LDH has good electrocatalytic performance toward OER (η100 = 340 mV) and HER (η100 = 310 mV). In addition, RSS-LDH can be used as an active bifunctional catalyst in overall water splitting with a low cell voltage of 1.42 V at 10 mA cm−2 (1.64 V at 100 mA cm−2) and stable operation of 10 h (100 mA cm−2). This strategy can provide a new method for the recovery of rusty stainless steel and provide a new application for electrocatalysis and energy transformation. [ABSTRACT FROM AUTHOR]

The combination of different material properties to face severe conditions has been always demanded by different industrial sectors. Traditionally, this has been achieved by conventional manufacturing of multiple materials with several steps and joining processes. However, manufacturing the entire component within the same process by additive manufacturing and the combination of two different materials is presented as a potential via to explore. In this study, three IN718/SS316 multimaterial samples were designed and successfully manufactured by a novel multilaser head deposition, wire-based Directed Energy Deposition (DED-wire) technology. Multimaterial-sandwich design strategies composed of two, three and four layers per material led to S1, S2, and S3 samples, respectively. In all of them, the direct transition between materials was applied. The cross-section of the three multimaterial samples was analyzed by optical microscopy to verify the influence of the number of the material layer on the defect appearance like porosity, cracks or lack-of-fusion. Evolution of the hardness property across the XZ direction of the three samples was assessed, and the microstructure of the IN718 region, IN718/SS316 interphase and SS316 region was evaluated across the XZ build direction (multimaterial gradient) and in the XY direction (single layer of SS316 or IN718). It was found that the multimaterial-sandwich design strategy of four layers per material employed for processing sample S3 led to IN718/SS316 interphases without the presence of relevant defects. The sample processed with two layers per material (S1) presented a similar crack pattern at each IN718-SS316 interface, but only very small and isolated pores were identified in S2 and S3 samples. A Microstructure composed of very fine grains together with a smooth transition zone was generated in a sample processed by S3. The three multimaterial samples resulted in a gradient of the hardness properties, decreasing the average hardness value from IN718 region, IN718/SS316 interphase to the SS316 region. S3 showed the hardness profile with the highest: IN718 region (55 ± 6 HRC), IN718/SS316 interphase (34 ± 1 HRC) and SS316 region (9 ± 2 HRC), where the value of IN718 is significantly higher compared to that of the conventional IN718 material (47 HRC). [ABSTRACT FROM AUTHOR]

Incremental sheet metal forming is known for its high flexibility, making it suitable for fabricating low-batch, highly customized complex parts. In this article, a localized multipass toolpath referred to as localized reforming, with reverse forming in a region of interest, is employed within the double-sided incremental forming (DSIF) process to manipulate the mechanical properties of a truncated pyramid formed from austenitic stainless steel sheet, SS304, through deformation-induced martensite transformation. DSIF forms a clamped sheet through localized deformations by two opposing tools. The toolpath effect in localized reforming is examined in terms of martensite transformation, geometrical accuracy, and thickness distribution. The results are compared with a conventional toolpath, i.e., forming in a single pass. The results show that varying toolpaths lead to different martensite transformation levels, while final geometry and thickness remain similar. The study demonstrates that localized reforming significantly increases martensite transformation in the specified region, i.e., the center of the pyramid wall, to ~70%, with a martensite fraction remaining around 25% elsewhere. In comparison, using a single pass forming toolpath leads to a decreasing martensite fraction from the base of the pyramid toward the apex, due to the heat generated, with values <10% along the entire wall. Through finite element simulation, it is shown that the increase in martensite transformation of the region of interest is with the plastic deformation accumulation during the reverse pass. These findings highlight the potential to tailor mechanical properties in specific areas using a reforming toolpath in DSIF. [ABSTRACT FROM AUTHOR]

ABSTRACT Cyclic pressures can cause fatigue failure in the brazed joints and plates of the plate heat exchangers (PHEs). This study examines the fatigue behavior of PHEs made from 316L and 304L steels brazed with copper foils employing strain‐controlled fatigue tests to explore if 304L could replace 316L in the existing production line for cost reduction. Fatigue tests were conducted at four different load levels with a stress ratio of zero and a frequency of 5 Hz. Finite Element Analysis was used to assess strain distribution and estimate PHE lifespan based on generated strain versus number of cycles to failure curves. The microstructural analysis revealed that copper diffuses more easily into 316L than 304L, and using 50 μm thick foil causes more defects compared with 100 μm foil. It was shown that 316L joints have a significantly increased fatigue life compared with 304L. Both 316L and 304L met the 15‐year lifetime requirement set by manufacturers. [ABSTRACT FROM AUTHOR]

Marine oil exploration is important yet greatly increases the risk of oil leakage, which will result in severe environment pollution and economic losses. It is an urgent need to develop effective underoil adhesives. However, realizing underoil adhesion is even harder than those underwater, due to the stubborn attachment of a highly viscous oil layer on target surface. Here, inspired by endocytosis, a tough gel tape composed of zwitterionic polymer network and zwitterionic surfactants is developed. The amphiphilic surfactants can form micelle to capture the oil droplets and transport them from the interface to gel via electrostatic attraction of polymer backbone, mimicking the endocytosis and achieving robust underoil adhesion. Benefiting from the oil‐resistance of polymer backbone, the gel further realizes a combination of i) long‐term adhesion with high durability, ii) repeated adhesion in oil, and iii) renewable adhesion efficiency after exhausted use. The tape exhibits an ultra‐high adhesive toughness of 2446.86 J m−2 to stainless steel in silicone oil after 30 days' oil‐exposure; such value of adhesive toughness surpasses many of those achieved in underwater adhesion and is greater than underoil adhesion performance of commercial tape. The strategy illustrated here will motivate the design of sustainable and efficient adhesives for wet environments. [ABSTRACT FROM AUTHOR]

In addressing issues related to defects in laser quenching technologies, this study undertakes surface passivation treatment on 2205 duplex stainless steel. The investigation explores the impact of different laser parameters on the corrosion resistance of the passive film on the steel surface. The findings may provide theoretical references for the laser passivation treatment and corrosion resistance mechanism of steel surfaces. [ABSTRACT FROM AUTHOR]

ABSTRACT This paper investigates the ability of the self‐heating method to characterize the fatigue behavior of 316L stainless steel produced by Laser Powder Bed Fusion. Nearly dense cylinders are built vertically using various process parameters corresponding to various volumetric energy densities. Fatigue specimens are then machined from these cylinders and polished. Fully reversed tension–compression fatigue tests (R = −1) are conducted. The self‐heating method is used for the estimation of the fatigue limits. These fatigue limits are compared to results obtained from S‐N curves in the high cycle regime. Whatever the set of process parameters, the self‐heating curves show three distinct domains of heat dissipation. Thanks to microstructure analysis, fractographic observations, and correlations with S–N curves, these domains can be closely linked to damage mechanisms associated or not with defects. [ABSTRACT FROM AUTHOR]

Methods such as gas stripping and vacuum-assisted gas stripping (VAGS) result in significant removal of water from the bioreactor, thus requiring continuous water replenishment in the bioreactor. In this study, we developed a hydrophobic stainless steel meshes capable of selectively recovering concentrated ABE stream from the bioreactor during VAGS. Three stainless steel meshes with pore sizes of 180 µm, 300 µm, and 425 µm were made hydrophobic and oleophilic with zinc oxide (ZnO) and polydimethylsiloxane (PDMS). Butanol concentrations in the model solutions range from 3 to 10 g/L which mimic concentrations typically produced during batch ABE fermentation. The meshes were integrated in a 5-L bioreactor containing 2.5 L of operational ABE model solution followed by the evaluation of selective extraction of ABE from both cell-free and Clostridium beijerinckii-rich ABE model solutions. The results show that the 180-µm ZnO/PDMS-coated mesh retained 54–64% more water in the bioreactor without C. beijerinckii cells and 61–65% more water with cells compared to the uncoated mesh. Furthermore, the butanol concentration of condensates recovered with 180-µm ZnO-PDMS-coated mesh was up to 10.8-fold greater than that of uncoated counterpart. Our data demonstrate that the developed ZnO-PDMS mesh can recover high concentrations of ABE while selectively retaining water in the bioreactor. Additionally, this technology demonstrates the potential for real-time ABE recovery during the fermentation of lignocellulosic and colloidal materials, without the concern of clogging the separation system. Key points: • Hydrophobic mesh enhanced water retention in the bioreactor by up to 1.65-fold. • Butanol concentration in the collected condensate was increased by up to 10.8-fold. • Hydrophobic mesh is compatible with fermentation of lignocellulose. [ABSTRACT FROM AUTHOR]

Hot deformation behavior of the maraging stainless steel is studied in temperature range from 900 to 1150 °C and strain rate from 0.1 to 10 s−1. When the deformation temperature is 900−950 °C, the abnormal stress increase is observed at the end of the flow curves. Transmission electron micrographs reveal that the Laves phase at the interface between prior austenitic (γ) and high‐temperature ferrite (δ) impedes hot deformation. The microstructure analysis shows that the dynamic recrystallization (DRX) mechanism of γ and δ is discontinuous DRX and continuous DRX, respectively. When the specimens are deformed at 950 °C, the extent of DRX at a strain rate of 5 s−1 is higher than at 0.1 s−1. This anomaly is due to adiabatic heating causing the actual deformation temperature at high strain rate (ε.$\overset{.}{\epsilon}$) to be higher than at low ε.$\overset{.}{\epsilon}$, indicating that DRX is more influenced by temperature compared to ε.$\overset{.}{\epsilon}$. The influences of adiabatic heating and friction are corrected. Strain‐dependent constitutive equation is developed based on the revised flow curves, yielding an average absolute relative error of 4.69% and a correlation coefficient of 0.99; the prediction accuracy exceeds 90% when the relative error is within 10%. [ABSTRACT FROM AUTHOR]

In metal additive manufacturing (AM), processing parameters can affect the probability of macroscopic defect formation (lack-of-fusion, keyholing, balling), which can, in turn, jeopardize the final product's integrity. A printability map classifies regions in the processing space where an alloy can be printed with or without porosity defects. However, the creation of these printability maps is resource-intensive. Previous efforts to generate printability maps have required single-track experiments on pre-alloyed powder, limiting the utilization of these printability maps for the high-throughput design of printable alloys. We address these challenges in the case of Laser Powder Bed Fusion AM (L-PBF-AM) by introducing a fully computational, predictive approach to create printability maps for arbitrary alloys. Our framework uses physics-based thermal models and a variety of defect formation criteria. We benchmark the predictive ability of the proposed framework against literature data for the following commonly printed alloys: 316 Stainless Steel, Inconel 718, Ti-6Al-4V, AF96, and Ni-5Nb. Furthermore, we deploy the framework on NiTi-based Shape Memory Alloys (SMAs) as a case study. We scrutinize the accuracy of various sets of defect criteria and use these accuracy measurements to create an uncertainty-aware probabilistic framework capable of predicting the printability maps of arbitrary alloys. This framework has the potential to guide alloy designers to potentially easy-to-print alloys, enabling the co-design of high-performing printable alloys. [ABSTRACT FROM AUTHOR]

Aluminium foam sandwich panels (AFSPs) have a high impact resistance and are suitable for a wide range of engineering applications. To improve corrosion resistance, this paper proposes an anti-corrosion sandwich panel with stainless steel as the upper sheet. Drop hammer impact tests were performed on a total of ten AFSPs to investigate their dynamic response and failure patterns. To assess the deformation performance of AFSPs, a laser displacement meter was used to obtain the bottom centre displacement. The effects of the impact energy and the thickness of each component of AFSPs on the peak impact force and deformation performance were studied. Test results showed that the thickness of each component had notable effects on the impactor and bottom displacements. In addition, the effect of the unit mass of the components in AFSPs on decreasing the bottom displacement was discussed. Compared to increasing the aluminium foam and lower sheet thicknesses, increasing the upper sheet thickness was more effective in decreasing the bottom displacement. A finite element model of AFSPs was developed to conduct parameter analysis, indicating that impactors with larger diameters resulted in higher peak forces and reduced deformation of AFSPs. [ABSTRACT FROM AUTHOR]

Coronary artery disease (CAD) is characterized by narrowing and subsequent blockade of coronary arteries, and imposes a significant health and economic burden. Stent and scaffold devices are introduced in advanced CAD to improve vascular stability and restore blood flow. Although in vitro flow systems like the Chandler loop have been developed to enhance the understanding of interactions between device materials, their coatings, and vascular cells, imaging-based in vitro analysis of device performance is limited. In this study, we established a novel stent flow chamber system designed to assess the thrombogenicity of bioresorbable magnesium scaffold (RMS) and stent materials in vitro. Additionally, we compared the thrombogenicity – an important clinical parameter in stent performance – of the Magmaris-316 L stainless steel stent with its predecessors, Magmaris RMS and a prototype of the third-generation RMS (DREAMS 3G). Analysis of platelet adhesion and coverage of the different devices under flow conditions demonstrated that the Magmaris RMS exhibits reduced thrombogenicity compared to the Magmaris-316 L stainless steel stent. Moreover, thrombogenicity of the DREAMS 3G prototype, composed of BIOmag material, is further decreased compared to its predecessors. The observed reduction in thrombogenicity of the DREAMS 3G prototype in vitro suggests additional improvements in clinical safety and efficacy, highlighting its promise for treating CAD. Future research on this prototype may thus open avenues for analyzing other blood components and patient-derived endothelial cells. In line with the 3R principles, this approach may also help reduce the need for animal testing. [ABSTRACT FROM AUTHOR]

To investigate the surface integrity of 17-7PH stainless steel welded structural components used in aviation, laser shock peening (LSP) with different power densities was applied to stainless steel welded joints. The microstructural morphology, structural features, full-width at half-maximum, microhardness, and surface roughness of the stainless steel welded joint specimens before and after LSP were characterized and measured using SEM, TEM, XRD, a microhardness tester, and a high-resolution confocal microscope. The effects of different laser power densities on the microstructure and properties of the stainless steel welded joints were explored. Results indicate that the stainless steel welded joints exhibit a typical BCC phase. Laser shock peening promotes grain refinement in the welded joints, leading to the phase transformation of residual austenite into martensite. The surface roughness of the specimen is positively correlated with laser power density. At a power density of 5.17 GW/cm2, the surface roughness increased to 1.919 μm, which is 117.08% higher than that of the non-peened specimen. The microhardness of the specimens shows a decreasing trend with increasing power density. When the power density is 2.79 GW/cm2, the microhardness of the specimen significantly increases to 462.94 HV0.5, which is 22.26% higher than that of the non-peened specimen. [ABSTRACT FROM AUTHOR]

Syngas, mostly hydrogen and carbon monoxide, has traditionally been produced from coal and natural gas, with biomass gasification later emerging as a renewable process. It is widely used in fuel synthesis through the Fischer–Tropsch (FT) process, where the H2/CO ratio is crucial in determining product efficiency and quality. In this sense, this study aimed to reform an emulated syngas resulting from the supercritical water gasification of biomass, tailoring it to meet the H2/CO ratio required for FT synthesis. Conditions resembling dry reforming were applied, using temperatures from 600 to 950 °C and steel wool as a catalyst. Additionally, the effects of Inconel and stainless steel as reactor materials on syngas reforming were investigated. When Inconel was used, H2/CO ratios ranged between 1.04 and 1.84 with steel wool and 1.28 and 1.67 without. When comparing reactions without steel wool performed either in the Inconel or the stainless steel reactors, those using Inconel consistently outperformed the stainless steel ones, achieving CH4 and CO2 conversions up to 95% and 76%, respectively, versus 0% and 39% with stainless steel. It was concluded that the Inconel reactor exhibited catalytic properties due to its high nickel content and specific oxides. [ABSTRACT FROM AUTHOR]

To better cope with stress in emergencies, emergency personnel undergo virtual reality (VR) stress training. Such training typically includes visual, auditory and sometimes tactile impressions, whereas olfactory stimuli are mostly neglected. This concept paper therefore examines whether odors might be beneficial for further enhancing the experience of presence and immersion into a simulated environment. The aim is to demonstrate the benefits of VR civilian stress training for emergency personnel and to investigate the role of odors as stressors by manipulating the degree of perceived psychophysiological stress via olfactory impressions. Moreover, the current paper presents the development and validation of a convenient and portable fragrance dosing system that allows personalized odor presentation in VR. The presented system can transport reproducible small quantities of an air-fragrance mixture close to the human nose using piezoelectric stainless steel micropumps. The results of the fluidic system validation indicate that the micropump is suitable for releasing odors close to the nose with constant amounts of odor presentation. Furthermore, the theoretical background and the planned experimental design of VR stress training, including odor presentation via olfactory VR technology, are elucidated. [ABSTRACT FROM AUTHOR]

Bipolar plates are one of the most important components of proton exchange membrane fuel cells. With the miniaturization of bipolar plate flow channel sizes and the increasing demand for precision, springback has become a key focus of research in the bipolar plate forming process. In this paper, the hydroforming process for 316L stainless steel bipolar plates was studied, and an FEM model was built to examine the stress and strain at various locations on the longitudinal section of the plate. Modeling accuracy was validated by the comparison of experimental profile and thickness distribution. The effects of forming pressure and grain size on springback behavior are discussed. The results show that with increasing forming pressure, the springback value decreases initially, followed by an increase, but then again decreases. When the forming pressure is 80 MPa–100 MPa, the deformation of the lower element of the upper rounded corner is not uniform with more elastic regions, and the springback is positively correlated with forming pressure. The springback distribution pattern on the cross-section of the bipolar plate changes from a normal distribution to a distribution of "M" shape with increased pressure. The larger the grain size, the lower the yield strength elastic proportion, resulting in a decrease in springback of the sheet. The maximum amount of springback of the bipolar plate is 3.1 μm when the grain size is 60.7 μm. The research results provide a reference for improving the forming quality of metal bipolar plates with different flow channel shapes. [ABSTRACT FROM AUTHOR]

Depositing a tritium permeation barrier on the surface of materials is a key method for reducing tritium permeability. During actual operational processes, the surface of the tritium permeation barrier may experience mechanical damage, such as spalling and scratches. The hydrogen permeability resistance of the coating will degrade due to such forms of mechanical damage. It is a significant engineering challenge to evaluate the impact of these damages on the coating's tritium resistance. In this experiment, the mechanical damage to the FeAl/Al2O3 tritium permeation barrier on 316L stainless steel was simulated through scratching, debonding, and thermal shock. Subsequently, a hydrogen isotope gas drive permeation (GDP) test was conducted. The influence of the degree of mechanical damage on the coating's tritium permeation behavior was assessed and discussed. The results indicate that, under the same damage mechanism, the coating's tritium permeability resistance is positively correlated with the integrity of the coating. Additionally, the impact of scratches on the coating surface is more severe than that of other damage mechanisms. [ABSTRACT FROM AUTHOR]

In the construction area, as well as in the restoration of old and historical buildings, different metallic materials are frequently in contact with gypsum plaster. Due to the high porosity of gypsum plaster, and particularly in high relative humidity environments, the risk of corrosion exists. In the present work, carbon, galvanized and stainless steel, as well as copper, were embedded in gypsum plaster (with varying water/gypsum ratios) and exposed to different environmental conditions, and the corrosion rate was assessed by electrochemical techniques. Stainless steel showed very low corrosion rates, carbon and galvanized steel showed considerable corrosion rates, and copper showed moderate corrosion rates. The higher the humidity, the higher the corrosion rate, independently of the water/gypsum ratio. A comparison with results obtained for the same materials embedded in mortar was performed. Except for stainless steel, the corrosion rates obtained in gypsum are higher than those obtained in mortar, being this difference up to two orders of magnitude. The differences in the pH of both matrices explained the lower corrosion rates measured in mortar. [ABSTRACT FROM AUTHOR]

Sealing is an important prerequisite for downhole heater work. This paper proposes a combination of soft and hard, and welding sealing programs, which were analysed using theoretical calculations, numerical simulation, and in-situ testing. The results show that 316 stainless steel can meet the stuffing seal requirements. The first stuffing leads to compression and gradual reduction, while the second stuffing essentially does not deform. Stuffing deformation fills the gap in the sealing hole, creating a sealing layer. The compression rate is 0.43%, 8.45%, and 12.64%, indicating that the locking stress should be more than 2000 N. The temperature at the weld is heated by heat conduction and distributed in a concentric circle. Thermal stress will influence the 50 mm barrier, but the 100 mm boundary will be mostly unaffected. Actually, the thermal stress that destroys the weld seal may be reduced by adjusting the heater output or raising the gas injection rate. During the beginning of the in-situ heat injection, the temperature of the heating rods rises simultaneously with the outlet temperature. Consequently, both show opposite tendencies. The heat generated by the heating rods will cause the injected gas to be preheated in advance. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to report the development and experimental evaluation of two kinds of PANI@semiconductor based photocathodic anti-corrosion coating, for application on stainless steel substrates. Design/methodology/approach: PANI was in situ chemical polymerized on TiO2 and BiVO4 particles, and FT-IR and SEM/EDS were used to understand the characteristics and elemental distribution of the composite particles. Composite coatings, which consisted of epoxy, PANI@TiO2 or PANI@BiVO4 and graphene, were prepared on the 304L stainless steel. Photoelectrochemical response measurement, electrochemical tests and immersion tests were used to assess the anti-corrosion performance of the prepared coatings in 45°C 3.5 wt.% NaCl solution. And the corrosion protection mechanism was further explained by combining with surface observation. Findings: The photoelectrochemical response tests revealed the good photocathodic effect of the coatings, and the reversible oxidation-reduction properties of PANI (pseudocapacitive effect) leading to the repeated usage of the coatings. Consequently, the anti-corrosion mechanism of the composite coating is attributed to the physical barrier effect of the coating, the anodic protection effect of PANI and the photocathodic and energy store effect. Originality/value: These kind coatings could prevent corrosion from day to night for stainless steel, which has great engineering application prospects on stainless steel corrosion protection. [ABSTRACT FROM AUTHOR]

In this study, polyacrylonitrile was modified to polyamidoxime to enhance foam stabilization and decontamination rate. Polyamidoxime was combined with graphene oxide, 1 wt% of saponins, and 1 wt% of alkyl glycosides to formulate the PAO/GO foam decontaminant. The outcomes demonstrated resulted in the half-life of the foam extending from 32 to 308 min. The PAO/GO foam decontaminant displayed α-ray decontamination rates of 93.30%, 98.34%, and 99.81% on stainless steel, tile, and glass surfaces. Hence, the dual functional PAO/GO in stabilizing foam while enhancing decontamination rates underscores its potential for radioactive decontamination. [ABSTRACT FROM AUTHOR]

The study aims to comprehend the behavior of nitrogen in the argon oxygen decarburization (AOD) process during the production of nitrogen‐alloyed stainless steels, where the precise adjustment of nitrogen content plays a crucial role in enhancing productivity. Furthermore, the objective is to investigate the rate of change in nitrogen content when blowing a mixture of nitrogen and argon, instead of using pure nitrogen or argon alone. Hence, both nitrogenation and denitrogenation cases are examined, and kinetic models are developed. While solution thermodynamics can predict the final nitrogen content, the kinetics are influenced by the gas flow rate, steel temperature and composition, and levels of the surface active elements in the steel. By integrating a previously developed thermodynamic equilibrium equation with the kinetic models, nitrogen contents in the range of 0.150–0.400% can be reliably predicted. Consequently, the equations can be applied to predict nitrogen content during both the nitrogenation and denitrogenation stages in the reduction and desulfurization phases of the AOD process. [ABSTRACT FROM AUTHOR]

This paper investigates the behavior of a medical guidewire within a vessel with a specific focus on its buckling, commonly known as tip load. The guidewire is simulated as a variable section microshaft embedded in an elastic environment, and a comprehensive buckling analysis is carried out based on the modified couple stress theory (MCST). The fundamental frequency is determined by applying Hamilton's principle and Rayleigh's method. A formula for calculating the buckling force is subsequently introduced. Numerical simulations were conducted to analyze the impact of the material properties, tapered tip length, core thickness, slenderness ratio, and material length scale parameter on the tip load and penetration force. Furthermore, a comparative study was carried out to validate the proposed formulation. The findings derived from this research can provide valuable insights for the optimization and exploration of various parameters related to medical guidewires. The findings indicate that coronary guidewires with lengths exceeding 10 cm exhibit minimal variations in tip load, whereas those with lengths below this threshold experience a substantial decrease of 65–75% in both tip load and penetration force when the length is doubled. In addition, nitinol guidewires demonstrate greater flexibility, with their tip load being nearly 75% lower than that of stainless steel guidewires of equivalent dimensions. Moreover, there is a notable increase in penetration force with an expanding radius, with tapered tips resulting in an approximate 20–30% increase in penetration force. [ABSTRACT FROM AUTHOR]

Fouling, the accumulation of undesirable material on manufacturing equipment surfaces, poses a pervasive challenge in industrial processes. In the food industry, the complex interactions among these compounds can give rise to stubborn deposits that deviate from conventional cleaning protocols. In this work, the forces and removal mechanisms of model fouling agents composed of mixtures of starch, whey protein, and lard deposited on solid surfaces of relevant industrial interest (i.e. stainless steel, aluminium, and PTFE) are investigated using a multi-length scale approach, involving milli-manipulation and a lab-simulated Clean-In-Place (CIP) system. The forces involved in the removal process, the types of failure observed when the deposits are subjected to shear stress (adhesive, mixed, or cohesive), and the performance of the CIP system are systematically analysed as a function of the cleaning treatments applied. For stainless steel surfaces, alkaline treatment seems to facilitate the cleaning of lard and starch deposits, while the whey foulant removal tends to be more effective using hot water under the conditions tested. Hot water is effective for stainless steel and PTFE surfaces, reducing the mechanical shear stress required, while the alkaline treatment demonstrated superior efficacy for aluminium surfaces. These findings emphasise the importance of customising cleaning protocols for CIP optimisation. [ABSTRACT FROM AUTHOR]

In order to improve the quality and efficiency of the sheet grinding and reduce the problems of distortion, local overwear, and ununiformity induced by grinding, an experimental study on the grinding of the sheet was carried out based on electromagnetic drive—the magnetic abrasive tool (MAT). Based on nonlinear fitting between the surface roughness Ra values and the variables, the microcomputer controls the current to form a transmission magnetic field-driven—the MAT—on the surface of the sheet to analyze the force and explore the force of the MAT and the characteristics of the movement, and find the core structure of the electromagnet and the coil layout of the better parameters. The MAT grinding method based on the electromagnetic drive was carried out for machining the SUS304 sheet workpiece, and the effect of current, machining gap, and magnetic field conversion frequency was analyzed. Based on the experimental study, the mathematical model was built, and the optimized combination of process parameters was validated and verified. The response surface methodology (RSM) was used for experiment design; the optimized combination of process parameters was derived as follows: current 0.72A, machining gap 0.93 mm, and magnetic field conversion frequency 149 ms. The MAT grinding with the electromagnetic drive the surface of the sheet, there is no local overwear phenomenon, the grinding surface is smooth and even, the micro-morphology and uniformity are well, and the mill efficiency is improved, which is a more significant advantage compared with the traditional grinding method. [ABSTRACT FROM AUTHOR]

Parts manufactured by wire arc additive manufacturing (WAAM) are characterized by a peculiar surface morphology, namely, surface waviness, that negatively affects the fatigue performance. To exploit the full potential of WAAM and minimize the need for postproduction work, it is crucial to utilize the components in the as‐built state. This is because conventional machining techniques, typically employed for postprocessing operations, severely curtail the freedom of geometry of the components. This study focuses on an experimental and numerical characterization of the notch effect of the surface waviness for an AISI 308 LSi stainless steel. This is done by quantifying the fatigue notch factor in a probabilistic fashion, considering the results of ad‐hoc designed fatigue tests. A finite element model is developed by considering a 3D scan of the geometry of WAAMed plates, allowing to determine the theoretical stress concentration factor. The fatigue notch factor is also estimated from the numerical model by making use of the gradient correction according to the FKM guidelines. To validate the numerical approach, test data produced for different testing conditions are correlated by using the local stress approach, showing that classical methods are also applicable to additive manufactured parts. Experimental determination of notch effect of as‐built surface in thick WAAMed plates. An FE model is formulated to estimate fatigue notch factor using FKM guidelines S‐N curves for WAAMed specimens of AISI308LSi steel at different load ratio. [ABSTRACT FROM AUTHOR]

This paper presents an experimental inverse approach to simultaneously estimate the temperature-dependent thermal properties of AISI 316 stainless steel. The heat flux conducted to the sample was corrected by using a transducer, evaluating contact resistance at microscopic level, and performing experiments under vacuum. Estimates were severely biased when heat flux correction was not applied. Metaheuristics were used to enlarge the search space, which can cover the thermal properties of all known metallic materials, thereby taking advantage of better thermal modeling adequacy. The estimation reliability was shown by comparison with literature data, statistical significance, uncertainty analysis, and inverse heat flux retrieval. [ABSTRACT FROM AUTHOR]

The Hirtisation® process is an electro-chemical process, wherein the electrolyte can easily access both external and internal surfaces. The process shows promising results in both support structure removal and reduction of surface roughness, and has the potential to solve the productivity and quality trade-off in powder bed fusion – laser beam (PBF-LB) processing. In this study, the role of the microstructure and surface topography on the capability of the Hirtisation® process to lower the PBF-LB produced surface roughness, has been investigated. A detailed microstructure analysis by SEM was used to determine the effect of the Hirtisation® process on removal of sintered powder, the effects on melt pool boundaries and grain boundaries, and thus the final surface quality. The Hirtisation® process significantly reduced surface roughness thanks to the complete removal of sintering powder from the as-built surface. Additionally, preferential material removal was detected along melt pool boundaries, leading to creation of notches of up to 10 µm in depth. [ABSTRACT FROM AUTHOR]

Compatibility tests are carried out on Ni-based Hastelloy alloys and stainless steel under the influence of the molten chloride salt NaCl-CaCl2-CeCl3 to investigate the corrosion behavior of molten salts with structural materials. Weight change measurements before and after the reaction tests show that the Hastelloy alloys have better corrosion resistance than stainless steel. The effects of molten salt purification on the corrosion behavior in the Hastelloy alloys are explored. The composition of the reacting phases is identified from transmission electron microscopy analysis and the corrosion mode is homogeneous corrosion with Cr and Fe diffusion, followed by Mo and Ni elution. [ABSTRACT FROM AUTHOR]

Fused Filament Fabrication (FFF) is one of the most popular extrusion based metal Additive Manufacturing (AM) Technologies, which has unique advantages in the rapid prototyping of thermoplastic materials, enabling the fabrication of metal parts with low mechanical anisotropy and no residual stress. However, the mechanical properties and dimensional accuracy of FFF printed parts are susceptible to changes in various printing parameters, which affects the FFF application in large-scale manufacturing. This study experimentally studied the effect of various printing parameters namely layer thickness (0.1, 0.2, 0.3, and 0.4 mm), raster angle (0°, 90°, + 45°/−45°, and 0°/90°), raster width (0.3, 0.35, 0.4, and 0.45 mm), and infill density (70, 80, 90, and 100%) on mechanical properties and dimensional accuracy of 316L stainless steel fabricated by FFF. The results showed that the infill density was the most important factor affecting the mechanical properties, followed by the layer thickness, and it was found that higher values of infill density and lower layer thickness result in better tensile strength. Layer thickness was also the main factor affecting the dimensional accuracy, which increased with the decrease in the layer thickness. [ABSTRACT FROM AUTHOR]

A large variety of ultrafast laser‐matter interaction regimes and different processed surface finishing qualities of stainless steel can be achieved by varying the laser processing parameters. The optimization of the laser fluence to the most efficient ablation also leads to the lowest surface roughness of the ablated material. High laser fluence together with a high pulse repetition rate leads to heat accumulation, which results in the formation of microstructures with various morphology and scales. The use of GHz bursts allows a rough stainless‐steel surface to be smoothed and even polished. In this work, the fast and high‐quality milling of 2.5D cavities is demonstrated. Laser beam spot optimization is used to increase the throughput of the high‐power femtosecond laser (67.8 W), resulting in an ablation rate of 13 mm3 min−1. The complex cavities are produced by laser milling and cutting in layers. The formation of surface structures on stainless steel because of laser irradiation has been demonstrated. The possibilities of further GHz burst polishing are examined on previously laser‐milled stainless steel using with lowest possible surface roughness. The ability to polish the surface with microstructures below the original roughness is demonstrated by bursts of ultrashort pulses with a repetition rate in the GHz range. It has been demonstrated that mold milling in stainless steel designed for LED diffusers can be fabricated using a modern femtosecond laser source together with beam size optimization technique for efficient ablation with low surface roughness, layer‐by‐layer milling techniques, and GHz burst polishing techniques. [ABSTRACT FROM AUTHOR]

Soft grippers, generating movement immediately, are generally based on flexible materials actuated by air pressure and comprised of bulky parts, including valves, compressors/pumps, motors, and tubes. In this work, a compact soft gripper with the ability to actuate with a low boiling point liquid (acetone) is presented. SolidWorks 2021 software and 3D printing technology are used to design and manufacture the gripper molds, respectively. The constitutive material of the soft gripper body is highly flexible Ecoflex. A silver‐coated nylon fabric (SCNF) heater reinforced with stainless steel yarn (SSY) covering the external surface of the gripper is designed and manufactured using Autocad 2021 and a laser cutting machine, respectively. The idea is inspired by floating the gripper in warm water to provide smooth heat over a large surface area. The available commercial software Abaqus2021 is used to simulate the mechanical deformation of the gripper, and its results are verified with experimental results. The parameter's effect including the voltage and low boiling liquid volume on achievable force and actuating time are investigated. The relation between the electrical, thermal, and mechanical properties of the presented gripper is discussed in detail. [ABSTRACT FROM AUTHOR]

Laser powder bed fusion (LPBF) involves depositing, melting, and solidifying metal powder particles layer by layer to create 3D components. In this study, a deep fundamental understanding on how process parameters—laser power, scan speed, and hatch spacing—affect the melt pool, densification, microstructure, hardness, and thermal behavior of 420 stainless steel (420SS) parts produced by such technology is provided. The conducted investigation considers five levels of laser power and hatch spacing, and four scan speeds. Optimal single tracks, based on geometry and profile, are achieved with laser powers between 40 and 80 W and a scan speed of 10 mm s−1. In the multitrack analysis, it is indicated that a dense, smooth surface is obtained with a hatch spacing of 250 μm, corresponding to an overlapping rate of ≈30%. The 420SS samples show high densification (≈99%) and low surface roughness (≈3.62 μm). The microstructure consisted of martensite laths and retained austenite. The hardness and thermal conductivity of the samples are measured at 540 HV and 15.3 W m−1 K−1, respectively. In this study, the understanding of the process–structure–property relationships in LPBF of 420SS is expanded. [ABSTRACT FROM AUTHOR]

The purpose of this study was to fully explore the mechanical properties of five different doses of an Argon–Oxygen Decarburization slag mixture in an unconfined compressive strength test. The peak stress, elastic modulus, and stress–strain curve of the mixture were studied for 90 days. Based on the experimental data and according to the theory of damage mechanics, the concept of damage threshold (t) was introduced to construct a damage constitutive model. Referring to the damage threshold of concrete, that of the mixture was determined to be 0.7 times higher than the peak strain, and the correlation coefficient between the established model and the test curve was above 0.85. These results indicate that the addition of AOD slag and fly ash can cause hydration reactions, increase the quantity of hydration products, and enhance the peak stress and elastic modulus of the mixture. The maximum increases were 94.9% and 43.1%, respectively. Parameters a and b reflect the peak stress and brittleness of the mixture, respectively. The incorporation of Argon–Oxygen Decarburization slag can make the mixture less brittle and improve its properties. The incorporation of Argon–Oxygen Decarburization slag can protect the mixture from damage. The maximum decrease is 40.2%. [ABSTRACT FROM AUTHOR]

Wire-based directed energy deposition (WDED) is an emerging additive manufacturing process garnering significant attention due to its potential for fabricating metal components with tailored mechanical and microstructural properties. This study reviews the WDED process, focusing on fabrication techniques, mechanical behaviors, microstructural characteristics, and quality enhancement methods. Utilizing data from the Web of Science, the study identifies leading countries in WDED research and highlights a growing interest in the field, particularly in materials engineering. Stainless steel, titanium, aluminum, and copper-based alloys are prominent materials for WDED applications. Furthermore, the study explores post-processing techniques such as machining, heat treatment, and surface finishing as integral steps for quality enhancement in WDED components. [ABSTRACT FROM AUTHOR]

This study investigates the cytotoxicity of various orthodontic archwires, which are essential in directing tooth movement through biomechanical forces. With advancements in material science, different archwire materials have been developed to balance mechanical performance with aesthetic and biological considerations. The study focuses on evaluating the biocompatibility and mechanical properties of stainless steel, nickel–titanium, and chromium–cobalt archwires, particularly their cytotoxic effects on oral cavity cells. In vitro cell culture experiments with fibroblasts, combined with scanning electron microscopy (SEM) analysis, were conducted to assess cell viability and morphology. The results revealed significant differences in cytotoxicity, with copper wires showing high toxicity and causing extensive cell death, while nickel–titanium and chromium–cobalt wires supported better cell viability and healthier cell morphology. These findings highlight the importance of selecting archwire materials that ensure mechanical efficiency without compromising cellular health, emphasizing the need for ongoing assessment of material biocompatibility in the oral environment. [ABSTRACT FROM AUTHOR]

Magnesium rechargeable batteries (RMBs) are a promising alternative to lithium‐based ones. However, a major challenge in their advance concerns the development of aprotic electrolytes from which magnesium can be electrodeposited with high efficiency and without the formation of dendrites. Of note, the mechanism of the magnesium electrodeposition from aprotic electrolytes remains largely unexplored. In this study, we propose a combined experimental and theoretical approach based on the Scharifker‐Hills (S−H) mathematical model for the potentiostatic transients to analyse the nucleation and growth of magnesium during electrodeposition in order to shed light on the nucleation process and increase battery safety and cycle lifetime. The model is used to investigate the electrodeposition of magnesium from a Magnesocene (MgCp2)‐based electrolyte onto metal current substrates such as copper, nickel, aluminium and stainless steel. [ABSTRACT FROM AUTHOR]

Compatibility tests are carried out on Ni-based Hastelloy alloys and stainless steel under the influence of the molten chloride salt NaCl-CaCl2-CeCl3 to investigate the corrosion behavior of molten salts with structural materials. Weight change measurements before and after the reaction tests show that the Hastelloy alloys have better corrosion resistance than stainless steel. The effects of molten salt purification on the corrosion behavior in the Hastelloy alloys are explored. The composition of the reacting phases is identified from transmission electron microscopy analysis and the corrosion mode is homogeneous corrosion with Cr and Fe diffusion, followed by Mo and Ni elution. [ABSTRACT FROM AUTHOR]

Hydrogen fuel cells are gaining popularity in power-consuming devices due to their zero-emission characteristics. However, ohmic resistance, which arises from the resistance to electron flow through the electrodes and external circuit, can cause reduced efficiency and voltage drops in a fuel cell. This research aims to develop current collector plates for proton exchange membrane fuel cells with optimal design, high electrical conductivity, and thermal conductivity to mitigate ohmic resistance. Six different designs and five different materials-copper, brass, aluminum, stainless steel 316, and stainless steel 304 – were considered for this purpose. The study involved experimental electrical conductivity and fuel cell performance tests to identify the best material and design for the current collector. Results indicated that brass and copper exhibited the least resistivity and favorable material characteristics. Consequently, all six current collector plate designs were developed using brass and copper with various machining and finishing processes. Performance testing on a fuel cell test station revealed that brass current collector plate design 5, featuring open ratios, demonstrated superior performance. Ultimately, the optimum design and material selection of the current collector plates have led to the development of fuel cells with reduced ohmic resistance and improved overall performance. [ABSTRACT FROM AUTHOR]

The publication presents the results of research on the influence of hydrostatic burnishing process on the value of selected parameters of surface roughness, material ratio and surface hardness. The process was carried out on shafts made of the X5CrNi18-10 stainless steel. The prepared samples were subjected to a finishing turning process with constant cutting parameters, and then hydrostatic burnishing was performed on the surface. The tests determined the influence of the variable pressure exerted by the ball on the shaft surface. The evaluation of the research results showed a significant increase in hardness in the surface layer and an improvement in surface roughness parameters and material ratio. The machining process was carried out on a conventional lathe. [ABSTRACT FROM AUTHOR]

Background: Children with dental caries are treated with stainless steel metal crowns (SSC), but the aesthetics and precision still need to be improved. Currently, both 3D‐printed resin crowns (PRC) and computer‐aided design/computer‐aided manufacture (CAD/CAM) resin crowns (CRC) meet the clinical requirements for crown applications in terms of strength, production time, cost, and aesthetics. Aim: This study replaced SSC with customized resin crowns by 3D printing and CAD/CAM. Design: In this study, PRC, CRC, and SSC were used for incisor and molar restorations, and 60 crowns were made with 10 for each group. The fabrication efficiency, surface characteristics, marginal fit, and stability of the two different crowns were evaluated. Results: PRC and CRC show superior color and surface characteristics, though production times are longer (5.3–12.4 times and 3.3–9.1 times, respectively) than for SSC (p <.05). They, however, can be completed within 80 min. Edge gaps for PRC and CRC are significantly lower (13.0–19.2 times and 13.0–13.7 times) than for SSC (p <.05). All materials exhibit good stability. Conclusion: The 3D‐PRCs and CAD/CAM resin crowns may replace SSCs as a potential choice for clinical child caries. [ABSTRACT FROM AUTHOR]