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Wire- and arc-based additive manufacturing (WA-AM) technology is a prominent solution to produce components having large-scale dimensions in terms of elevated deposition rates, high material utilization efficiency, and cost effectiveness. Although many research works have explored the WA-AM process of 316L stainless steel, the selection of optimal input parameters for enhancing geometrical characteristics of the WA-AMed 316L stainless steel has not been addressed. In this paper, the variables—voltage (U), current (I), and traveling speed (V), were optimized to obtain the expected attributes of weld beads (WB) in the WA-AM of 316L SS. The empirical models of the width (BW), height (BH), and contact angle (CA) of WBs were developed using a BRFFNN (Bayesian regularized feed forward neural networks) model. To determine the best optimality, the non-dominated-sorting-genetic algorithm based on a grid partition (NSGA-GP) and TOPSIS (technique for order of preference by similarity-to-ideal solution) were adopted. The outcomes indicate that the developed BRFFNN models are adequate to predict the objectives (BW, BH, and CA). The optimized value of I, U, and V is 130 A, 22.0 V, and 0.30 m/min, respectively, which enable BW, BH, and CA to be improved by 22.97%, 11.24%, and 5.61%, respectively. The optimal parameters were used to successfully build a component without major defects, indicating their suitability for producing 316L SS components used in industrial applications. The outcomes have demonstrated the efficiency of the proposed optimization approach, which can also be used to predict optimal parameters of other AM and conventional manufacturing processes. [ABSTRACT FROM AUTHOR]

ABSTRACT This research studies the effect of variable stress levels on the rotating bending fatigue (RBF) tests of 316L stainless steel fabricated by the laser powder bed fusion (LPBF) method. The mechanical properties and fatigue behavior were evaluated to ascertain the correlation between the applied stress levels and microstructural changes that occurred during the fatigue experiments. These relationships were further investigated using a classical model developed on the Python platform. The microstructural analysis demonstrated that the face‐centered cubic structure was maintained throughout the application of stresses, varying from 255 to 402 MPa along with no phase changes. Nevertheless, the density of shear lines on the surface was substantially influenced by variations in stress levels as demonstrated by high‐stress areas in Kernel average misorientation maps. At lower stress levels, the model analysis exhibited a higher degree of reliability, with R2 values of 96.25% at lower stress rather than 89.30% at higher stress. [ABSTRACT FROM AUTHOR]

In-depth quality assessment of 3D-printed parts is vital in determining their overall characteristics. This study focuses on the use of 2D X-Ray diffraction (2D-XRD) and X-Ray micro-computed tomography (micro-CT) techniques to evaluate the crystallography and internal defects of 316L SS parts fabricated by the powder-based direct energy deposition (DED) technique. The test samples were printed in a controlled argon environment with variable laser power and print speeds, using a customized deposition pattern to achieve a high-density print (>99%). Multiple features, including hardness, elastic modulus, porosity, crystallographic orientation, and grain morphology and size were evaluated as a function of print parameters. Micro-CT was used for in-depth internal defect analysis, revealing lack-of-fusion and gas-induced (keyhole) pores and no observable micro-cracks or inclusions in most of the printed body. Some porosity was found mostly concentrated in the initial layers of print and decreased along the build direction. 2D-XRD was used for phase analysis and grain size determination. The phase analysis revealed single phase γ-austenitic FCC phase without any detectable presence of the δ-ferrite phase. A close correlation was found between Electron Backscatter Diffraction (EBSD) and 2D-XRD results on the average size distribution and the crystallographic orientation of grains in the sample. This work demonstrates the fast and reliable as-printed crystallography analysis using 2D-XRD compared to the EBSD technique, with potential for in-line integration. [ABSTRACT FROM AUTHOR]

Selective Laser Melting (SLM) is an advanced additive manufacturing technique that demands meticulous control over thermal dynamics to maintain the integrity and performance of manufactured parts. This study presents the development and validation of a thermal model designed to enhance the SLM process for 316L stainless steel (316L SS) and titanium alloy Ti6Al4V. A specially constructed Argon Chamber Setup, equipped with a 200 W continuous-wave (CW) fibre laser system, was used to create an SLM-representative environment for 316L SS, enabling precise experimental validation of the model. This validation serves as a robust baseline, facilitating the model's extension to more complex materials like Ti6Al4V, thereby supporting a cost-efficient and safe approach to initial testing. The rigorously validated thermal model offers a comprehensive link between experimental data and numerical simulations in SLM. It supports process optimisation by accurately predicting thermal behaviours, contributing significantly to additive manufacturing advancements. By fine-tuning processing parameters, this model enhances material characteristics, thereby providing practical insights applicable to industrial production and improving the consistency and quality of SLM-manufactured parts. [ABSTRACT FROM AUTHOR]

Niobium-based oxides have garnered increased attention in recent years for their remarkable enhancement of corrosion resistance, as well as biofunctional properties of various metallic materials, including 316L SS. However, the mechanical properties of these promising coatings have not been fully elucidated. This study investigated how much the environmental conditions (air, artificial saliva, and NaCl solution) impact the wear performance of 316L SS without and with Nb2O5 coatings deposited via the reactive sputtering technique. The results exhibited a notable decrease in friction coefficient (55% in air, 18% in artificial saliva, 10% in 0.9 wt% NaCl solution), wear area (46% in air, 36% in AS, 17.5% in 0.9 wt% NaCl solution), and wear rate (44.0% in air, 19.5% in AS, 12.0% in 0.9 wt% NaCl solution). Ultimately, the results obtained in the present study elucidate the synergistic mechanisms of corrosion and wear in 316L SS containing Nb2O5 coatings, highlighting its significant potential for applications in the biomedical sector. [ABSTRACT FROM AUTHOR]

316L stainless steel (SS) is widely applied as microimplant anchorage (MIA) due to its excellent mechanical properties. However, the risk that the oral microorganisms can corrode 316L SS is fully neglected. Microbiologically influenced corrosion (MIC) of 316L SS is essential to the health and safety of all patients because the accelerated corrosion caused by the oral microbiota can trigger the release of Cr and Ni ions. This study investigated the corrosion behavior and mechanism of subgingival microbiota on 316L SS by 16S rRNA and metagenome sequencing, electrochemical measurements, and surface characterization techniques. Multispecies biofilms were formed by the oral subgingival microbiota in the simulated oral anaerobic environment on 316L SS surfaces, significantly accelerating the corrosion in the form of pitting. The microbiota samples collected from the subjects differed in biofilm compositions, corrosion behaviors, and mechanisms. The oral subgingival microbiota contributed to the accelerated corrosion of 316L SS via acidic metabolites and extracellular electron transfer. Our findings provide a new insight into the underlying mechanisms of oral microbial corrosion and guide the design of oral microbial corrosion-resistant materials.

In-depth quality assessment of 3D-printed parts is vital in determining their overall characteristics. This study focuses on the use of 2D X-Ray diffraction (2D-XRD) and X-Ray micro-computed tomography (micro-CT) techniques to evaluate the crystallography and internal defects of 316L SS parts fabricated by the powder-based direct energy deposition (DED) technique. The test samples were printed in a controlled argon environment with variable laser power and print speeds, using a customized deposition pattern to achieve a high-density print (>99%). Multiple features, including hardness, elastic modulus, porosity, crystallographic orientation, and grain morphology and size were evaluated as a function of print parameters. Micro-CT was used for in-depth internal defect analysis, revealing lack-of-fusion and gas-induced (keyhole) pores and no observable micro-cracks or inclusions in most of the printed body. Some porosity was found mostly concentrated in the initial layers of print and decreased along the build direction. 2D-XRD was used for phase analysis and grain size determination. The phase analysis revealed single phase γ-austenitic FCC phase without any detectable presence of the δ-ferrite phase. A close correlation was found between Electron Backscatter Diffraction (EBSD) and 2D-XRD results on the average size distribution and the crystallographic orientation of grains in the sample. This work demonstrates the fast and reliable as-printed crystallography analysis using 2D-XRD compared to the EBSD technique, with potential for in-line integration.

Niobium-based oxides have garnered increased attention in recent years for their remarkable enhancement of corrosion resistance, as well as biofunctional properties of various metallic materials, including 316L SS. However, the mechanical properties of these promising coatings have not been fully elucidated. This study investigated how much the environmental conditions (air, artificial saliva, and NaCl solution) impact the wear performance of 316L SS without and with Nb2O5 coatings deposited via the reactive sputtering technique. The results exhibited a notable decrease in friction coefficient (55% in air, 18% in artificial saliva, 10% in 0.9 wt% NaCl solution), wear area (46% in air, 36% in AS, 17.5% in 0.9 wt% NaCl solution), and wear rate (44.0% in air, 19.5% in AS, 12.0% in 0.9 wt% NaCl solution). Ultimately, the results obtained in the present study elucidate the synergistic mechanisms of corrosion and wear in 316L SS containing Nb2O5 coatings, highlighting its significant potential for applications in the biomedical sector.

In this study, the melt pool size, precisely its width and depth, are numerically investigated for a wide range of values for both laser power and beam speed. A thermal model, developed on Ansys Additive Science, simulates the SLM of a single bead. A parametric study is achieved aiming at understanding the melt pool evolution and the defects appearing while varying these two parameters. The discussed porosity defects, namely the LOF and keyhole, are determined using the calculated melt pool dimensions and through mathematical correlations from the literature. Moreover, these numerical results are validated with experimental results for the reliability of the study. This investigation reveals a proportional relationship between the melt pool size and the laser power and an inversely proportional relationship with the scan speed. The optimal combination of these two parameters has to be well studied to avoid LOF and keyhole, which is afforded by this paper. At lower laser power levels, such as 100 W, it is advisable to choose a slower scan speed ranging from 400 to 500 mm/s. As the laser power increases, so does the optimal scan speed. For instance, with 150 W, the ideal speed falls between 600 to 900 mm/s. Similarly, for 200 W, the recommended scan speed range extends from 900 to 1200 mm/s, and for 250 W, the optimal speed range lies between 1100 and 1400 mm/s. [ABSTRACT FROM AUTHOR]

WC–Co cutting tools are widely used in harsh conditions, but the brittleness of this material can limit their use. Joining steels to WC–Co can provide an alternative, by combining the toughness of steel with the high hardness and wear resistance of WC–Co. The creation of textures at the bonding interface is known to increase the adhesion between materials, through a mechanical interlocking effect and an increase in the contact area. In this sense, this work proposes the laser surface texturing of WC–Co green compacts with cross-hatched and circular micropatterns and subsequent pressure-assisted sintering of the textured and sintered WC–Co with 316L SS powder to improve the bonding between materials. Results showed that the bonding of the textured multi-material was successfully processed and an interdiffusion zone was formed at the bonding interface without the presence of detrimental compounds. The addition of textures showed a tendency to increase the shear bond strength, with the cross-hatched micropatterns generally showing a higher bonding strength than the circular micropatterns. This approach showed to have the potential to improve the bonding between materials, thus contributing to the development of novel multi-material WC–Co/316L stainless steel cutting tools with enhanced properties and performance. [ABSTRACT FROM AUTHOR]

Gas tungsten arc welding (GTAW) is commonly used for joining pipelines; however, it often leads to discoloration in the heat-affected zone (HAZ). In this study, 316L pipes were welded with different concentrations of oxygen present in the argon purge gas during welding. The objective of this study was to investigate the effect of oxygen concentration in the protective gas on the pitting corrosion resistance of welded pipes. The experimental results showed that the thickness of the oxide layer formed in the HAZ depends on the concentration of oxygen in the protective gas. Increasing the oxygen concentration in the protective gas resulted in an increase in pitting corrosion resistance until a critical value, beyond which the resistance decreased. The results showed that the thickness of the oxide layer formed in the HAZ depends on the concentration of oxygen in the protective gas. Increasing the oxygen concentration in the protective gas increased the pitting corrosion resistance until a critical value, beyond which the resistance decreased due to the formation of iron oxide. This study provides valuable insights for improving the corrosion resistance of welded pipes in the oil and gas industry. [ABSTRACT FROM AUTHOR]

In this paper, Zr(Hf)xCN coatings were deposited onto 316L stainless steel (316L SS) substrates at 400 °C using the radio-frequency (R.F.) magnetron sputtering technique with Hf-Zr-C composite target materials. The influence of Hf element content on microstructure, mechanical properties, and corrosion resistance and platelet interaction with the surface of Zr(Hf)xCN coatings were then investigated. The results indicate that the microstructure, mechanical properties, and corrosion resistance of coatings depend on their chemical composition. Corrosion resistance and platelet interaction with the surface could be improved by adding Hf to the Zr2CN. By optimizing the Hf-Zr-C ratio, Zr(Hf)xCN coatings with excellent corrosion resistance were obtained. The ZrHfCN-3 coating with a Hf element content of 7.33% possesses excellent mechanical properties and good corrosion resistance. The result of the platelet interaction with the surface confirms that Zr(Hf)xCN coatings have better platelet interaction with the surface than 316L SS. [ABSTRACT FROM AUTHOR]

This study investigates the microstructure and corrosion behavior of the selective laser melted (SLM) 316L stainless steel in a Ringer's solution. Besides, the biocompatibility of the fabricated SLM alloy was investigated using MG63 cells. The wrought, SLM, and heat-treated at 450 °C (SLM-450) stainless steel alloys were picked for the investigation. Microscopy evaluation indicated that SLM and SLM-450 samples showed a cellular morphology due to the fast cooling rate the SLM process. SLM-450 sample showed a better corrosion performance compared to other samples. Charge transfer resistance of the SLM-450 after 330 h of immersion was two times higher than wrought and SLM samples in the corrosive solution, respectively. Moreover, the SLM-450 alloy revealed the highest biocompatibility, most probably because of the stress relief after heat treatment, the lower release of toxic cations, and the presence of round MnSiO 3 phase in the SLM-processed alloy. [ABSTRACT FROM AUTHOR]

316L stainless steel alloys are extensively used in orthopedic applications for the fixations and substitutions of defective bone tissues in the human body because of their excellent combination of mechanical and biological behavior. However, just like other metallic implants, they tend to release some toxic ions that may lead to serious health issues. Therefore, this study attempts to increase the alloy's resistance against corrosion while maintaining its good mechanical properties by applying a modified coating layer of PMMA-based composites titanium carbide as reinforcement material using dry electrostatic spray deposition (ESD) under constant conditions (25 kV, 15-20 cm distance, compressed air of 15 psi, and spraying angle about 45.0o for 3 0sec). The titanium carbide was added with ratios of (5, 10, 15, 20) wt. % respectively. The coatings’ surface morphology and phases were studied using Field Emission Scanning Electron Microscope, Energy-dispersive X-ray spectroscopy, and X-ray diffraction. Also, the biological behavior of the composite coated samples was studied by investigating their corrosion and wetting attributes. The results revealed that homogenous, uniform, crack-free coating layers and high surface wettability were obtained. Indicating the suability of PMMA/TiC for biomedical applications due to the alloy's improved corrosion resistance and biocompatibility.

The present work was focused on the corrosion properties and contact resistance behavior of poly(orthophenlyenediamine) (PoPD) coating on 316L SS bipolar plates. To reduce the corrosion rate and increase the interfacial conductivity of 316L SS bipolar plates, PoPD coating was deposited using an electropolymerization technique by the various monomer concentration of orthophenlyenediamine (oPD) on its surface. The presence of 1, 2, 4, 5- tetra substituted benzene nuclei of phenazine units in the polymer coating was confirmed by infrared spectroscopy. X-ray photoelectron spectroscopy analysis has confirmed the (%) of chemical composition in PoPD coating. The results of scanning electron microscopy analysis revealed that the uniform and compact coating with complete cover on 316L SS. The corrosion properties were investigated in 0.5 M H 2 SO 4 and 2 ppm HF solution at 80 °C. The polarization test results showed that the PoPD coating reduced the corrosion current density both in the PEMFC anode and cathode environments. The charge transfer resistance values were in the order of 316L SS ˂ 0.02 M PoPD ˂ 0.06 M PoPD ˂ 0.04 M PoPD. A very low interfacial contact resistance and good adhesion strength was observed for 0.04 M PoPD coating. The higher contact angle of 0.04 M PoPD coating explained the hydrophobic property and more benefit of water management in the PEMFC environment. The results of the analysis of total metal ion releases clearly explained that the low level of metal ions released for 0.04 M PoPD coating. The overall studies revealed the PoPD coating with optimized 0.04 M oPD concentration showed best performance and provided more anodic protection to 316L SS bipolar plates. • Anticorrosive performance of PoPD coated 316L SS was significantly increased. • PoPD coating withstands the physical barrier during long term immersion. • Lower contact resistance of PoPD coated 316L SS was greatly achieved. [ABSTRACT FROM AUTHOR]

The performance and durability of orthopedic implants are mainly determined by their surface integrity. Ball burnishing (BB) is a kind of finishing treatment which improves the surface dependant mechanical properties of metallic biomaterials. In this work, this process was applied on the flat surface of 316L stainless steel to enhance its microhardness and wear resistance. The mathematical modeling of microhardness Vickers was performed by the response surface method (RSM) based on Box–Behnken plans, and the optimum regime was applied under several passes to investigate the effect of number of passes (i) on the surface properties. The evolution of microhardness, nano-hardness and elastic modulus was then examined. Wear resistance, in terms of variation of Coefficient of friction and wear loss, was also investigated. Finally, XRD analysis was performed to evaluate any change in structure produced by BB. The results show that burnishing treatment permits to raise the microhardness by up to 38.3% and to reduce the wear loss by up to 65.2%. Nano-hardness and elastic modulus were also increased after application of the process. XRD patterns indicate that grain refinement was induced with no change in phases composition. The number of passes is proved effective in increasing the depth of the hardened layer, which influences subsequently on the frictional behavior of 316L stainless steel.

Impact of sintering temperature and aging time was investigated on purity and phase of hydroxyapatite powders synthesized through sol–gel process. Phase, composition, and morphology of the prepared hydroxyapatite powders were characterized using X‐ray diffraction (XRD), Fourier transform infrared (FT‐IR), and scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS). Plausible mechanism respective to the formation of HAP from the precursors Ca(NO3)2·4H2O and triethyl phosphite (TEP) by sol–gel process was determined from 31P NMR analysis. Further, the development of hydroxyapatite coatings on 316L SS metallic surfaces was done by varying the spin coating parameters such as spin speed, spin time, and sintering atmosphere, and their corrosion resistance behavior in SBF solution was evaluated by electrochemical impedance spectroscopy (EIS) and TAFEL polarization analysis. From the results, we inferred that the HAP coatings deposited on 316L SS surfaces at 3000 rpm/min under nitrogen atmosphere sintering have shown improved corrosion resistivity. The effect of aging time, sintering atmosphere, and spin speed was evaluated in terms of corrosion resistance behavior. [ABSTRACT FROM AUTHOR]

In this study, we have synthesized a new family of bioactive glass (BAG) comprising of SiO 2 , Na 2 O, CaO, K 2 O, P 2 O 5 and MgO via sol-gel route. The composition of these oxides has been selected in such a way that the BAG has a coefficient of thermal expansion close to the 316L stainless steel (SS). In vitro test by soaking the BAG in simulated body fluid (SBF) showed good bioactivity due to ion exchange between alkali ions from the BAG and the ions present in the SBF. The 316L SS substrates were textured using laser before application of BAG using sol-gel dip coating. Pull off test showed that the adhesion strength in case of textured and non-textured surfaces were 4.2 MPa and 2.46 MPa, respectively. This implies that texturing of the surface is helpful in increasing the adhesion strength of the coating. The bioactive glass-coated textured surface of 316L SS substrate showed better corrosion resistance in SBF than the bare substrate for which the respective corrosion current densities were 35 nA/cm2 and 353 nA/cm2, thereby indicating that the single layer sol-gel dip coating of bioactive glass improved the corrosion resistance of the 316L SS implants. The analysis of scanning electron microscopy (SEM) images of the coating after immersion in SBF shows the formation and growth of the apatite layer that will further inhibit the corrosion of the substrate. These results demonstrate the potential of the synthesized BAG as a coating material for 316L SS implants. [ABSTRACT FROM AUTHOR]

Sol-Gel-based reaction mixture sols have been long used to fabricate dense and uniform bioactive coatings with superior mechanical stability over metallic implants. On account of precise control over synthesis, fabrication, formed and low temperature of processing, this technology is one of the most feasible routes to produce bio-ceramic coatings. The study aims to develop a physical barrier over metal implants in form of bioinert Zirconia coatings, phase-stabilized using Dysprosium. The metallic substrates were cut into 10 mm × 10 mm samples and diamond polished after being polished with a 1000 grade emery sheet. Novel spin-coated zirconia films were fabricated over 316L Stainless steel substrates and were sintered at 600°C to obtain firm and uniform crack-free coatings. The thickness of the coatings was determined by ELCA-D meter thermal analysis was performed using TGA-DTA. Phase determination was performed using X-Ray diffraction followed by morphological investigations using Scanning electron microscopy. The corrosion resistance was evaluated with Polarization studies and electrokinetic data was derived using Tafel extrapolation. Biocompatibility evaluation was performed against MG-63 cell lines and RBCs along with bone-forming ability in vitro in SBF. Stable crack-free 3 Layer coatings fabricated at 2000 rpm for 3 s with a thickness of around 1 μm were found to be optimal for corrosion resistance behavior of steel implants at a low ICorr value of 0.501 µA/cm2 and adhesion strength of 40.93 MPa when untreated falling down to 39.92 MPa when immersed in SBF. The study concludes that medium rpm coatings sustain enough sol to produce crack-free coatings that form a strong physical barrier between body fluid and implant surface thereby reducing the attack of corrosive ions and protecting the implant surface without participating in any form of bioactivity but supporting native bone regeneration capabilities. [ABSTRACT FROM AUTHOR]

Sol-Gel-based reaction mixture sols have been long used to fabricate dense and uniform bioactive coatings with superior mechanical stability over metallic implants. On account of precise control over synthesis, fabrication, formed and low temperature of processing, this technology is one of the most feasible routes to produce bio-ceramic coatings. The study aims to develop a physical barrier over metal implants in form of bioinert Zirconia coatings, phase-stabilized using Dysprosium. The metallic substrates were cut into 10 mm × 10 mm samples and diamond polished after being polished with a 1000 grade emery sheet. Novel spin-coated zirconia films were fabricated over 316L Stainless steel substrates and were sintered at 600°C to obtain firm and uniform crack-free coatings. The thickness of the coatings was determined by ELCA-D meter thermal analysis was performed using TGA-DTA. Phase determination was performed using X-Ray diffraction followed by morphological investigations using Scanning electron microscopy. The corrosion resistance was evaluated with Polarization studies and electrokinetic data was derived using Tafel extrapolation. Biocompatibility evaluation was performed against MG- 63 cell lines and RBCs along with bone-forming ability in vitro in SBF. Stable crack-free 3 Layer coatings fabricated at 2000 rpm for 3 s with a thickness of around 1 µm were found to be optimal for corrosion resistance behavior of steel implants at a low ICorr value of 0.501 µA/cm2 and adhesion strength of 40.93 MPa when untreated falling down to 39.92 MPa when immersed in SBF. The study concludes that medium rpm coatings sustain enough sol to produce crack-free coatings that form a strong physical barrier between body fluid and implant surface thereby reducing the attack of corrosive ions and protecting the implant surface without participating in any form of bioactivity but supporting native bone regeneration capabilities. [ABSTRACT FROM AUTHOR]

Austenitic 316L Stainless Steel are TIG (Tungsten Inert Gas) welded and are water jet peened by varying two main parameters - pressure and stand-off distance. This induces compressive residual stresses by local plastic deformation. The residual stresses of samples before and after water jet peening are measured using XRD. TIG welded samples show residual tensile stress and peened samples show compressive stress. Compressive stresses in the range of 111MPa to 118MPa are induced by water jet peening, of which the samples peened with 50mm Stand-Off Distance (SOD) has more compressive residual stress. Samples peened with SOD of 50mm shows good corrosion resistance, micro hardness and good surface finish when compared to samples peened with SOD of 75mm. It has been observed that only SOD plays an important role in enhancing the properties after peening. The microstructure of the peened region in the weldment consists of fine grains due to impact of high pressure water jet. [ABSTRACT FROM AUTHOR]

In this study, seven 316L stainless steel (316L SS) bulks with different angles (0°, 15°, 30°, 45°, 60°, 75°, and 90°) relative to a build substrate were built via selective laser melting (SLM). The influences of different angles on the metallography, microstructure evolution, tensile properties, and corrosion resistance of 316L SS were studied. The 0° sample showed the morphology of corrugated columnar grains, while the 90° sample exhibited equiaxed grains but with a strong texture. The 60° sample had a good strength and plasticity: the tensile strength with 708 MPa, the yield strength with 588 MPa, and the elongation with 54.51%. The dislocation strengthening and grain refinement play a vital role in the mechanical properties for different anisotropy of the SLM-fabricated 316L SS. The 90° sample had greater toughness and corrosion resistance, owing to the higher volume fraction of low-angle grain boundaries and finer grains.

Graphene oxide incorporated hydroxyapatite hybrid films were coated on 316L stainless steel substrate with the aid of electrochemical studies at the voltage of −1.5 V for 30 min using three electrode arrangements. Purity and crystallinity of the formed HAP/GO composite coatings were examined using X-ray diffraction and Fourier transform infrared spectroscopic studies. Phase of the hydroxyapatite was not affected with incorporation of graphene oxide into its matrix. Well-ordered and compact coating morphology was observed for the electrochemically deposited HAP/GO on 316L substrate using the scanning electron microscopy. High-resolution transmission electron microscopic studies reveal the tight bonding and growth of HAP particles on to the sidewalls of GO sheets. Electrochemical studies for the HAP/GO composite coating against the physiological solution showed improved corrosion efficiency. Addition of GO into HAP enhances the apatite precipitation and bone-bonding ability. These results concluded that the electrochemical deposition of bioceramic coatings on implant may be treated as an effective method for orthopedic repair and replacements. [ABSTRACT FROM AUTHOR]

The present study focuses on evaluating the corrosion resistance of 316L stainless steel substrates with Polyvinylcarbazole (PVK)/TiO 2 hybrid nanocomposite coatings (HNC). Using the chronoamperometry approach, the HNC were electrochemically synthesized on 316L stainless steel substrates, incorporating various weight (%) 1 %, 2 %, 3 % of TiO 2 nanoparticles into the PVK matrix. The findings of the surface morphology investigation verified that the 316L SS had a dense and smooth PVK/TiO 2 coating. A low surface roughness and high contact value of the PVK/TiO 2 coatings are also responsible for the decrease in corrosion rate of the 316L SS. The corrosion protection efficiency of the PVK/TiO 2 HNC were investigated through open circuit potential (OCP) measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) analysis in 3.5 wt% NaCl solution. The corrosion rate obtained from the polarization studies of the HNC coatings as follows PVKT-2 < PVKT-3 < PVKT-1 < PVK < 316L SS. Results revealed that an optimal loading of 2 wt% TiO 2 nanoparticles significantly enhanced the corrosion resistance of the coating. The enhanced electrochemical impedance response for PVK/TiO 2 coatings was verified by EIS experiments. The study demonstrates that the incorporation of TiO 2 nanoparticles into the PVK matrix effectively creates a barrier layer at the coating-metal interface, inhibiting the entry of aggressive ions. Microhardness studies revealed the increase in hardness value of the PVK and PVK/TiO 2 coatings indicated the protective nature of the coating and provided high mechanical strength to 316L SS. The tape adhesion tests carried out on the coated specimens also indicated a good adhesion of the PVK/TiO 2 on the 316L SS surface. [Display omitted] • PVK-TiO 2 nanocomposite coating was successfully deposited on 316 L SS. • Corrosion resistance of the PVK–TiO 2 nanocomposite coated 316 L SS was improved. • Contact angle values of the PVK–TiO 2 nanocomposite coating was increased. [ABSTRACT FROM AUTHOR]

Polymer coatings are increasingly used in varied fields and applications from simple coatings of barrier to intricated nanotechnology based composite. In the present study, polyvinylidene fluoride(PVDF)/Hydroxyapatite (HA )coatings were produced by spin coating technique over 316L SS. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were used to observe the coated 316L SS substrates surface morphology. The corrosion protection efficiency of pure polyvinylidene fluoride and polyvinylidene fluoride/HA nanocomposite coatings on 316L SS was inspected using potentiodynamic polarization along with the ions release techniques in Hank’s solution. A superior biocompatibility and an improved protection performance against corrosion were obtained for the 316L SS samples with nanocomposite coatings compared with the pure polyvinylidene fluoride coatings and pristine 316L SS counterparts. The 316L SS samples coated by PVDF/HA nanocomposite showed enhanced corrosion protection within Hank’s solution. The corrosion of 316L SS samples within Hank’s solution increased from 92.99% to 99.99% when using 3wt% HA due to increasing the PVDF inhibition efficiency. Good agreements in the electrochemical corrosion parameters were obtained from using ions release and potentiodynamic polarization tests.

Polymer coatings are increasingly used in varied fields and applications from simple coatings of barrier to intricated nanotechnology based composite. In the present study, polyvinylidene fluoride(PVDF)/Hydroxyapatite (HA)coatings were produced by spin coating technique over 316L SS. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were used to observe the coated 316L SS substrates surface morphology. The corrosion protection efficiency of pure polyvinylidene fluoride and polyvinylidene fluoride/HA nanocomposite coatings on 316L SS was inspected using potentiodynamic polarization along with the ions release techniques in Hank's solution. A superior biocompatibility and an improved protection performance against corrosion were obtained for the 316L SS samples with nanocomposite coatings compared with the pure polyvinylidene fluoride coatings and pristine 316L SS counterparts. The 316L SS samples coated by PVDF/HA nanocomposite showed enhanced corrosion protection within Hank's solution. The corrosion of 316L SS samples within Hank's solution increased from 92.99% to 99.99% when using 3wt% HA due to increasing the PVDF inhibition efficiency. Good agreements in the electrochemical corrosion parameters were obtained from using ions release and potentiodynamic polarization tests. [ABSTRACT FROM AUTHOR]

The corrosion of a 316L stainless steel (SS) exposed to a humid gas flow polluted with HCl has been studied. The mixture is carried out in a reactor connected to two gas feedthroughs: one with wet air and one with HCl(g). The corrosion mechanism comprehension is based on several steps. The presence of humid air polluted by HCl involves the creation of a precursor film that can evolve to droplet formation. In contact with this acid and chloride concentrated electrolyte, the 316L SS corrodes producing soluble ferrous chloride. This corrosion product can evolve to the oxide formation, depending of the HCl concentration. For high concentrations, 316L SS corrodes uniformly. However, this phenomenon is accompanied by pits when the HCl concentration is not sufficient or the HCl flow is not continuous. The particularity of the corrosion mechanisms is shown as well as the problems using materials in an HCl‐polluted gaseous environment. [ABSTRACT FROM AUTHOR]

The influences of the plastic strain and strain rate on the corrosion behaviours of 316L stainless steel (316L SS) in a simulated cathodic environment of proton exchange membrane fuel cells (PEMFCs) are investigated using potentiodynamic curves, electrochemical impedance spectroscopy (EIS), Mott-Schottky plots and X-ray photoelectron spectroscopy (XPS). The results demonstrate that 316L SS is in the passive state in the simulated cathodic environment of PEMFCs and that a passive film can be formed on the cathodic bipolar plate, which is composed of 316L SS, during PEMFC operation. The passive film can protect 316L SS from further corrosion, and the corrosion resistance of the passive film on 316L SS reaches a maximum at a plastic strain of 20%. The corrosion resistance increases with the strain rate; thus, the maximal corrosion resistance corresponds to a plastic strain of 20%, and the corrosion protection increases with the strain rate. The XPS results demonstrate that the Cr 2 O 3 content in the passive film on 316L stainless steel reaches a maximum at a plastic strain of 20%, and the increased strain rate can increase the Cr 2 O 3 content. • A passive film can be formed on 316L SS in the cathodic environment of PEMFC. • The plastic strain has an evident effect on the corrosion behavior of 316L SS. • The plastic strain of 20% corresponds to the best corrosion resistance. • The increased strain rate can improve the corrosion resistance of 316L SS. [ABSTRACT FROM AUTHOR]

The influences of two types of heat-treatments on the corrosion behavior of 316L SS in the simulated cathodic environment of PEMFC, are investigated using potentiodynamic curve, electrochemical impedance spectroscopy (EIS), Mott-Schottky plot and auger electron spectroscopy (AES), respectively. The results show that 316L SS is in the passive state within the potential region from −0.1V SCE to 0.8V SCE in the simulated cathodic environment of PEMFC, and a passive film can be formed on 316L SS. The passivity of 316L SS in the simulated cathodic environment of PEMFC firstly increases and then degrades with the increased solid solution temperature or time, and the best passivity corresponds to the solid solution temperature at 1050 °C for 40 min among other solid solution treatments. While 316L SS heat-treated with the solid solution treatment at 1050 °C for 40 min plus aging treatment at 900 °C for 4 h, also has the best passivity in the same solution among other solid solution plus aging treatments. The best corrosion protection, lowest donor density and the highest thickness of the passive film corresponding to the solid solution temperature at 1050 °C for 40 min among other solid solution or solid solution plus aging heat treatments, and this treatment is mostly suitable for improving the anti-corrosion property of 316L SS in the simulated cathodic environment of proton exchange membrane fuel cell (PEMFC). • Two kinds of heat treatments were used to prepare the 316L stainless steel samples. • A passive film can be formed on 316L SS in the cathodic environment of PEMFC. • The heat treatment had an obvious effect of the film corrosion protection on 316L SS. • The solid solution treatment at 1050 °C corresponded to the best film corrosion on 316L SS. [ABSTRACT FROM AUTHOR]

The Cu2O/TiO2 p-n heterojunction composite photoelectrodes were prepared by depositing Cu2O nanoparticles on the surface of TiO2 nanotubes via anodic oxidation and constant current deposition. Field emission scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analyses showed that Cu2O nanoparticles not only deposited on the surface of TiO2 nanotube array, but also on the wall of TiO2 nanotubes. The Cu2O deposition amount could be adjusted by changing the deposition time. The photoelectrochemical cathodic protection (PECCP) performance of the prepared photoelectrodes for 316L stainless steel (SS) was tested under visible light. The constant current deposition time had a significant effect on the PECCP performance of Cu2O/TiO2-X photoelectrodes and Cu2O/TiO2-20 had the best PECCP performance for the coupled 316L SS. This was attributed to the appropriate amount and thickness of Cu2O to form p-n heterojunctions with TiO2, in which separation of the photogenerated carriers was accelerated and transfer of the photogenerated electrons to 316L SS for PECCP was facilitated. [ABSTRACT FROM AUTHOR]

Nowadays, material aging issues in the nuclear industry have received wide attention as they need costly maintenance strategies to deal with. Therefore, it is important to study the degradation mechanism of materials to improve their service life. In this study, in-situ electrochemical measurement techniques were used to investigate the fretting corrosion synergistic damage mechanism of 316L SS tube against zirconia ceramics plate in the solution with different dissolved oxygen (DO) concentrations. The results show that a more uniform passive film with the main composition of corundum oxides γ-Fe 2 O 3 and oxyhydroxide γ-FeOOH formed on the wear scar under higher DO concentration, which hindered the charge transfer and improved corrosion resistance. The passive film modifies contact pressure and changes wear behavior, resulting in a 55.5 % reduction in the fretting corrosion damage. The main damage mechanism changes from abrasive wear to a mixing mechanism of surface fatigue and abrasive wear. The contribution of the synergistic damage effect was quantified, which is the key part of fretting corrosion damage and weakens with the increase of DO concentration. According to the experimental results, a prediction model of corrosion-induced wear damage was proposed based on the Archard equation, Hertz contact theory, and passive film coverage model. • In-situ electrochemical measurement technique was used during fretting corrosion. • The fretting corrosion damage mechanism depends on the concentration of DO. • The synergistic damage effect was clarified by a quantitative calculation method. • A prediction model of corrosion-induced wear damage was proposed. [ABSTRACT FROM AUTHOR]

This work aims to investigate the influence of niobium and carbon nanostructured coatings on the corrosion resistance of the 316L SS. The coated and uncoated specimens were morphologically and structurally characterized by using OM, SEM/EDX, DRX, FTIR, Raman spectroscopy and XPS techniques. The corrosion behaviour was assessed by OCP, PPc, EIS as well as immersion tests in 0.6 mol L−1 NaCl solution. In addition, the average contact angles were used to evaluate the surfaces free energy by the Van Oss interfacial tension component theory approach. Results showed that the surface treatments positively influenced the corrosion resistance of the 316L SS and the coatings act as a protective barrier against corrosion process. The reactive sputtering technique increased the wettability of the surfaces in relation to the base material. Considering applications in aggressive media, the 316L SS/Nb 2 O 5 specimen exhibits superior performance when compared to the base material and 316L SS/carbon. [Display omitted] • Nanostructured niobium and carbon coatings deposited on the 316L SS surface. • Reactive sputtering technique as a powerful tool to produce niobium and carbon coatings. • The surface treatment increased the corrosion resistance of the 316L SS. • Nb 2 O 5 coating presented a superior performance to uniform and localised corrosion processes. • Reactive sputtering technique increased the wettability of the functionalized samples. [ABSTRACT FROM AUTHOR]

316L stainless steel (SS) is widely applied as microimplant anchorage (MIA) due to its excellent mechanical properties. However, the risk that the oral microorganisms can corrode 316L SS is fully neglected. Microbiologically influenced corrosion (MIC) of 316L SS is essential to the health and safety of all patients because the accelerated corrosion caused by the oral microbiota can trigger the release of Cr and Ni ions. This study investigated the corrosion behavior and mechanism of subgingival microbiota on 316L SS by 16S rRNA and metagenome sequencing, electrochemical measurements, and surface characterization techniques. Multispecies biofilms were formed by the oral subgingival microbiota in the simulated oral anaerobic environment on 316L SS surfaces, significantly accelerating the corrosion in the form of pitting. The microbiota samples collected from the subjects differed in biofilm compositions, corrosion behaviors, and mechanisms. The oral subgingival microbiota contributed to the accelerated corrosion of 316L SS via acidic metabolites and extracellular electron transfer. Our findings provide a new insight into the underlying mechanisms of oral microbial corrosion and guide the design of oral microbial corrosion-resistant materials., Competing Interests: The authors declare no competing interests., (© 2024 The Authors.)

The development of biomaterials for implants nowadays requires materials with superior mechanical and physical properties for enhanced osseointegration and sustained longevity. This research work was conducted to investigate the influence of nano hydroxyapatite (HAp) powder mixed electrical discharge machining (PMEDM) on surface morphology and microhardness of modified 316L stainless steel surface. The chosen process parameters were discharge current, pulse on/off duration and gap voltage in order to analyze the selected output responses. HAp concentration (15 g/l) along with reverse polarity was kept constant for current experimentation. The experimental results testified that surface morphology of PMEDM surface was significantly improved along with augmentation of 79% in microhardness (HV) of HAp modified surface of medical grade stainless steel. Furthermore, XRD and SEM characterization confirmed the deposition of calcium, phosphorous and inter-metallic compounds on HA-PMEDMed surface. The surface thus produced is expected to facilitate better bone-implant adhesion and bioactivity. [ABSTRACT FROM AUTHOR]

Ceramic oxide coatings are widely used in biomedical applications due to their ability to bond with bone and soft tissues. In the present study, we focus on improving the biocompatibility and corrosion resistance with self-healing properties of 316L SS by coating with cerium (Ce) incorporated niobium oxide (Nb 2 O 5) bioceramics synthesized by sol-gel technique. The effect of Ce concentrations in Nb 2 O 5 on the surface properties of 316L SS and its self-healing process during electrochemical corrosion in simulated body fluid (SBF) were deeply analyzed. The surface functional groups, morphology, chemical composition and phase transitions present in the coatings were analyzed using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), high resolution scanning electron microscopy (HRSEM) with elemental dispersive X-ray (EDX) and X-ray diffraction (XRD) studies respectively. Chemical states of Ce and Nb in the Ce incorporated niobium oxide coating were identified by X-ray photoelectron spectroscopic (XPS) studies. Results show that Ce is present as both Ce3+ and Ce4+ oxidation states in CeO 2 form whereas Ce3+ is the main species and Nb is present as Nb5+ oxidation state exists in Nb 2 O 5 form. Ce incorporated Nb 2 O 5 coatings improved the surface roughness (R a) and hydrophilic nature of 316L SS, studied through atomic force microscopy (AFM) and water contact angle measurements. Electrochemical studies were performed for the specimens immediate and after 7 days immersions in SBF solution to evaluate the corrosion resistance with self-healing behavior. Results show that increased corrosion resistance with reduction in current density (i corr) and corrosion potential (E corr) and breakdown potential (E break) shifts towards more positive potentials from potentiodynamic polarization studies whereas increased impedance values and good capacitance behavior in the low frequency regions were measured from electrochemical impedance spectroscopic (EIS) studies for the Ce incorporated Nb 2 O 5 coated 316L SS specimens. Cell culture studies were performed on specimens using osteoblast MG 63 cells, among those Ce incorporated Nb 2 O 5 coatings were showed enhanced biocompatibility for 316L SS with improved cell adhesion, significant cell spreading, proliferation and differentiation of cells. Schematic representation of the self-healing behavior of Ce incorporated Nb 2 O 5. Unlabelled Image • Successful fabrication of functional Ce incorporated Nb 2 O 5 coating over 316L SS to best fit for implant applications. • Surface morphology and properties of 316L SS were greatly enhanced by Ce incorporated Nb 2 O 5 coatings. • Enhanced corrosion resistance with self-healing behavior by Ce incorporated Nb 2 O 5 coating over 316L SS. • The Ce incorporated Nb 2 O 5 coated 316L SS exhibited more biological activity in promoting MG 63 osteoblast cells. [ABSTRACT FROM AUTHOR]

Brass alloys are used in many applications. However, improving their surface properties would help to increase their service life. For that, this study proposed to deposit using high velocity oxygen fuel (HVOF), nickel-chromium-boron-silicon (NiCrBSi) alloy, and 316L stainless steel (SS) coatings on brass substrates and investigate the mechanical properties and corrosion resistance of the coatings. The surface–interface morphologies, phases, and porosity of the coatings were analyzed using a scanning electron microscope and 3D profilometer. The adhesive strength and microhardness of the NiCrBSi and 316L SS coatings were also studied. Corrosion investigations were carried out using the salt fog test in an acetic acid salt spray atmosphere according to the NF EN ISO 9227 standard. This work showed that the 316L SS coatings presented a lower microhardness and higher adhesion strength than the NiCrBSi coatings despite their lower corrosion resistance. This could be explained by the microstructure of the coatings, the 316L SS coatings exhibiting more defects such as pores, un-melted particles, and oxides. [ABSTRACT FROM AUTHOR]

The corrosion behaviour of 316L stainless steel (316L SS) in 10% H2SO4 solution (94°C) with various concentrations of NaCl (0–0.085 mol/L) was studied by immersion corrosion test and polarization methods, combined with SEM/EDS, XPS and XRD tests. The influence of NaCl on the corrosion of 316L SS was investigated. The results showed that at lower NaCl contents (0–0.0085 mol/L), the steel presented a general corrosion characteristic with a higher corrosion speed and the corrosion rate increased with the NaCl content. At higher NaCl contents (≥0.017 mol/L), the corrosion rate decreased remarkably due to the protective corrosion products precipitation which contained metallic sulphates and NaHSO4. However, the higher concentration of chloride ions caused micron pitting-like local dissolution on the surface. The addition of Na2SO4 effectively inhibited general corrosion of the steel because of a dense and continuous products layer enriched with more NaHSO4 and metallic sulphates formed. [ABSTRACT FROM AUTHOR]

In this study, single-layer and three-layer nickel-based coatings were fabricated on 316L SS by laser additive manufacturing. The phase characterization, microstructure observation, and microhardness analysis of the coatings were carried out by X-ray diffraction (XRD), scanning electron microscope (SEM), and microhardness tester. And the wear resistance of the coatings was analyzed through dry sliding friction and wear test. The results show that the cross-section microstructure of the three-layer nickel-based coating is different from that of the single-layer one under the influence of heat accumulation; the dendrite structure in the central region of the former is equiaxial dendrite, while that of the latter still remains large columnar dendrites. The existence of solid solution phase γ-(Fe, Ni) and hard phases of Ni17Si3, Cr5B3, Ni3B in the coating significantly improve the wear resistance of the coating, and the microhardness is nearly 2.5 times higher than that of the substrate. However, the average microhardness of multilayer cladding coating is about 48 HV0.2 higher than that of the single-layer cladding coating. In addition, the fine surface structure of the three-layer nickel-based coating improves the wear resistance of the coating, making this coating with the best wear resistance.

Highlights • Poor vacuum prevents Li wetting due to the formation of a layer of complex Li compounds. • Li can easily react with O element from SS surface oxide layer to prevent Li wetting. • Baking, He-GDC, Li coating and surface textured structure improve Li wetting. Abstract Improved liquid Li wettability on a solid substrate surface is a necessary component for the research and development of blanket coolants, tritium breeders, and first wall materials for fusion device. A systemic investigation of Li wetting a 316 L SS surface, along with interfacial interactions has been successfully carried out. The results indicate that base vacuum pressure of the vessel, substrate temperature, and surface conditions of the substrate are the main factors that influence Li wetting property. It has been found that poor vacuum (>10−1Pa) along with high impurity content, especially water, can prevent Li wetting due to the formation of a layer of complex Li compounds, such as LiOH, Li 3 N and Li 2 CO 3. Also, Li wetting can be gradually improved with an increase of substrate temperature, mainly due to a decrease in surface tension of Li droplets. Moreover, Li wetting can be further improved by effective surface conditioning. It has been demonstrated that baking was beneficial in order to release impurity gas by thermal desorption and thereby achieve high vacuum during Li wetting, which resulted in a reduction of > 50 °C in Li wetting temperature on the SS substrate. He-GDC and Li coating can further decrease Li wetting temperatures to the Li melting point (∼180 °C) by avoiding the formation of Li 2 O at the interfacial surface during Li wetting. This is achieved primarily because these conditioning techniques can effectively remove and isolate the SS surface oxide layer (Cr 2 O 3), respectively, which was verified by the related testing of interfacial interactions between liquid Li and SS. Finally, surface textured structures with trenches ∼μm in size, are demonstrated to promote Li spreading along the groove direction, driven by capillary forces. These results provide the technical support for liquid Li applications in future fusion reactors. [ABSTRACT FROM AUTHOR]

The large-area Cu/SS ribbed plate is very significant for the fusion engineering but is difficult to produce by regular cold or hot processing. This thesis takes Cu-alloy plate and 316L SS ribbed plate as materials and adopts a new form of charging to carry out the deepened study and optimization of the supporting formwork from perspectives of design, filling scheme and welding parameters. It prepares a large-area dual-metal ribbed plate by the explosive weld and conducts the shear strength test, metallographic observation, scanning electron microscopy and micro-hardness test of the weld interface. The result indicates that most weld interface is the wavy metallurgical bond interface of the direct transition of Cu/SS but “coronary” vortexes containing metallic oxide exist on both sides of the crest. Crystalline grains near the bond interface are lengthened and thinned, the micro-hardness is increased significantly and the bond strength of interface is even greater than that of copper. [ABSTRACT FROM AUTHOR]

Medical grade 316L stainless steel was laser surface melted (LSM) using continuous wave Nd-YAG laser in argon atmosphere at 1 and 5 mm/s. The treated surfaces were characterized using electron backscatter diffraction to study the influence of top surface crystallographic orientation and type of grain boundaries on corrosion resistance, wettability, and biocompatibility. The laser scan velocity was found to have a marginal influence on the surface roughness and the type of grain boundaries. However, the crystal orientation density was found to be relatively high in 1 mm/s samples. The LSM samples showed a higher concentration of {101} and {123} planes parallel to the sample surface as well as a higher fraction of low-angle grain boundaries. The LSM samples were found to exhibit better surface wettability and enhanced the viability and proliferation of human fetal osteoblast cells in vitro when compared to the untreated samples. Further, the corrosion protection efficiency of 316L stainless steel was improved up to 70% by LSM in as-processed condition. The increased concentration of {101} and {123} planes on surfaces of LSM samples increases their surface energy, which is believed to be responsible for the improved in vitro cell proliferation. Further, the increased lattice spacing of these planes and high concentration of low-energy grain boundaries in LSM samples would have contributed to the better in vitro corrosion resistance than untreated 316L stainless steel. Our results indicate that LSM can be a potential treatment option for 316L stainless steel-based biomedical devices to improve biocompatibility and corrosion resistance. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 569-577, 2018. [ABSTRACT FROM AUTHOR]

Single-step electrophoretic co-deposition (EPD) technique was used to enhance the bioactivity of the 316L stainless steel (316L SS) surface by bioactive glass/chitosan composite coatings. Two modified glass compositions of Bioglass® by the addition of boron were utilized to prepare such composite layers, and the Bioglass® was synthesized for comparison. Different EPD coating factors were studied. Namely, voltage, time, glass powder, and chitosan concentrations, to obtain crack-free and good adhesive coatings. The achieved surfaces were characterized by SEM/EDX, TGA, XRD and FTIR and their wettability and roughness were investigated. The in vitro bioactivity of the coated metals was compared in simulated body fluid (SBF) and Dulbecco's modified eagle medium (DMEM) for up to 15 days. The electrochemical corrosion behavior of the coated metals was evaluated using potentiodynamic polarisation and impedance techniques in the two biological solutions SBF and DMEM at 37 °C. The results showed that the achieved coatings were uniform, homogenous and crack-free with desirable thickness. Moreover, the coating layers were exhibited by very high wettability, and their roughness values ranged from 170 ± 18 to 234 ± 17 μm. The in vitro bioactivities proved that the coating layers represented a better ability to form hydroxyapatite crystals on their surfaces in SBF than in DMEM. The corrosion resistance of 316L SS was improved by the bioactive composite coatings. [ABSTRACT FROM AUTHOR]

In the present study, Nb 2 O 5 (NZ0) composite coatings with various concentrations of zinc (NZ2, NZ4 & NZ6) are produced on 316L SS by sol-gel method with the aim of improving its antibacterial activity, bone formability and corrosion resistance properties. This work studied the surface characterization of NZ0, NZ2, NZ4 & NZ6 coated 316L SS by ATR-FTIR, XRD, HR-SEM with EDAX. The synthesized coatings were different in the morphological aspects, NZ0 shows mesoporous morphology whereas irregular cluster like morphology was observed for the zinc incorporated coatings. The chemical composition of the NZ0 and NZ4 composite coatings were studied by XPS and the results revealed that the zinc exist as ZnO and Nb as Nb 2 O 5 in the coatings. The increase in the concentration of zinc in Nb 2 O 5 increases the hydrophilic nature identified by water contact angle studies. The potentiodynamic polarization studies in simulated body fluid reveals the increase in polarization resistance with decrease in current density (i corr ) and electrochemical impedance spectroscopic studies with increase in charge transfer resistance (R ct ) and double layer capacitance (Q dl ) were observed for NZ4 coated 316L SS. The inhibition of Staphylococcus aureus and Escherichia coli bacteria were identified for NZ4 coated 316L SS by bacterial viability studies. The NZ4 coated 316L SS showed better Osseo-integration by spreading the MG 63 osteoblast cells. The study results imply that zinc incorporated Nb 2 O 5 (NZ4) composite coating exhibits antibacterial activity and also enhance the corrosion resistance and biocompatibility of the 316L SS. [ABSTRACT FROM AUTHOR]