Bare 316L Stainless Steel Research Articles

Bioinspired Self-Adhesive Multifunctional Lubricated Coating for Biomedical Implant Applications.

In the realm of clinical applications, the concern surrounding biomedical device-related infections (BDI) is paramount. To mitigate the risk associated with BDI, enhancing surface characteristics such as lubrication and antibacterial efficacy is considered as a strategic approach. This study delineated the synthesis of a multifunctional copolymer, embodying self-adhesive, lubricating, and antibacterial properties, achieved through free radical polymerization and a carbodiimide coupling reaction. The copolymer was adeptly modified on the surface of stainless steel 316L (SS316L) substrates by employing a facile dip-coating technique. Comprehensive characterizations were performed by using an array of analytical techniques including Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, optical interferometry, scanning electron microscopy, and atomic force microscopy. Nanoscale tribological assessments revealed a notable reduction in the value of the friction coefficient of the copolymer-coated SS316L substrates compared to bare SS316L samples. The coating demonstrated exceptional resistance to protein adsorption, as evidenced in protein contamination models employing bovine serum albumin and fibrinogen. The bactericidal efficacy of the copolymer-modified surfaces was significantly improved against pathogenic strains such as Staphylococcus aureus and Escherichia coli. Additionally, in vitro evaluations of blood compatibility and cellular compatibility underscored the remarkable anticoagulant performance and biocompatibility. Collectively, these findings indicated that the developed copolymer coating represented a promising candidate, with its facile modification approach, for augmenting lubrication and antifouling properties in the field of biomedical implant applications.

Enhanced Long-Term Corrosion Resistance of 316L Stainless Steel by Multilayer Amorphous Carbon Coatings.

Diamond-like carbon (DLC) coatings are effective in protecting the key components of marine equipment and can greatly improve their short-term performance (1.5~4.5 h). However, the lack of investigation into their long-term (more than 200 h) performance cannot meet the service life requirements of marine equipment. Here, three multilayered DLC coatings, namely Ti/DLC, TiCx/DLC, and Ti-TiCx/DLC, were prepared, and their long-term corrosion resistance was investigated. Results showed that the corrosion current density of all DLC coatings was reduced by 1-2 orders of magnitude compared with bare 316L stainless steel (316Lss). Moreover, under long-term (63 days) immersion in a 3.5 wt.% NaCl solution, all DLC coatings could provide excellent long-term corrosion protection for 316Lss, and Ti-TiCx/DLC depicted the best corrosion resistance; the polarization resistances remained at ~3.0 × 107 Ω·cm2 after immersion for 63 days, with more interfaces to hinder the penetration of the corrosive media. Meanwhile, during neutral salt spray (3000 h), the corrosion resistance of Ti/DLC and TiCx/DLC coatings showed a certain degree of improvement because the insoluble corrosion products at the defects blocked the subsequent corrosion. This study can provide a route to designing amorphous carbon protective coatings for long-term marine applications in different environments.

Corrosion Resistance, Interfacial Contact Resistance, and Hydrophobicity of 316L Stainless Steel Bipolar Plates Coated with TiN/Amorphous Carbon Double Layer under Different Carbon Target Currents

To improve the corrosion, interfacial contact resistance, and hydrophobicity of bipolar plates used in proton-exchange membrane fuel cells, a series of TiN/amorphous carbon double-layer coatings was prepared on 316L stainless steel using magnetron sputtering. The structure of the amorphous carbon was controlled with different carbon target currents. The changed rules in the coating structure and performance under different carbon target currents were studied. Due to appropriate sputtering energy, an appropriate carbon target current reduced the grain boundary of the coating, resulting in a smoother surface, and increased the content of sp2 hybrid carbon. Compared with uncoated 316L stainless steel, the samples coated with amorphous carbon showed greatly improved corrosion resistance and conductivity. At a carbon target current of 5 A, low contact resistance and high corrosion resistance were achieved simultaneously. The significant improvement in corrosion resistance is attributed to the improvement in the quality of the coating surface. Due to the appropriate carbon target current increasing the content of sp2 hybrid carbon in the coating, the contact resistance of the coating was reduced. When the carbon target current was 5 A, the interfacial contact resistance of the sample was 3.9 mΩ·cm2, which is significantly lower than that of bare 316L stainless steel. After constant potential polarization testing, the coating still exhibited good conductivity.

The electrochemical and in-vitro study on electrophoretic deposition of chitosan/gelatin/hydroxyapatite coating on 316L stainless steel

In the present study, chitosan/gelatin/hydroxyapatite (HA) coating was developed on 316L stainless steel (SS) via electrophoretic deposition (EPD). This type of film exhibits a hierarchical structure consisting of hydroxyapatite particles dispersed in a chitosan/gelatin matrix. An array of different analytical, electrochemical, and bioactive techniques was used to investigate the coatings. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that HA particles are well dispersed in the chitosan/gelatin matrix. X-ray photoelectron spectroscopy (XPS) results revealed that phosphorus is well bonded to the oxygen and well confirmed by the Fourier transform infrared (FTIR) spectrum. The electrochemical studies of the chitosan/gelatin/HA and bare 316L SS were conducted by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results indicated that corrosion resistance (conducted in simulated body fluid (SBF)) is mainly contributed by the HA particles embedded in the chitosan/gelatin matrix. Moreover, pitting potential of the composite coatings increased compared to that of the bare 316L SS. Chitosan/gelatin/HA developed apatite crystals upon immersion in SBF, thus confirming the bioactive nature of the coating. Furthermore, the coating was cyto-compatible and allows the osteoblast cells to proliferate and grow. The chitosan/gelatin/HA is a suitable candidate for biomedical applications regrading to mechanical and chemical attack.

Improvement in Corrosion Resistance and Interfacial Contact Resistance Properties of 316L Stainless Steel by Coating with Cr, Ti Co-Doped Amorphous Carbon Films in the Environment of the PEMFCs.

In order to obtain films with high corrosion resistance and excellent interfacial contact resistance (ICR) on 316L stainless steel used for bipolar plates in proton-exchange membrane fuel cells (PEMFCs), Cr, Ti co-doped amorphous carbon films were prepared on 316L stainless steel. The preparation method for the coating was magnetron sputtering. The doping amount of the Ti element was controlled by a Cr target and a Ti target current. The change in the structure and properties of the coating after the change from Cr single-element doping to Cr and Ti co-doping was studied. The change rule of the structure and properties of the coating from Cr single-element doping to Cr and Ti co-doping was studied. An increase in the Ti content led to a decreased grain boundary, a flatter surface, and a higher sp2-hybridized carbon content. TiC and CrC nanocrystals were formed in the amorphous carbon structure together. The amorphous carbon films doped with Cr and Ti simultaneously achieved a low ICR and high corrosion resistance compared with single-Cr-doped amorphous carbon. The enhanced corrosion resistance was attributed to the decreasing grain boundary, the formation of the TiC crystal structure, and the smaller grain size. The best performance was obtained at a Ti target current of 2A. Compared with bare 316L stainless steel, the corrosion resistance of Cr, Ti co-doped amorphous carbon (Icorr = 5.7 × 10-8 A/cm2, Ti-2 sample) was greatly improved. Because Ti doping increased the content of sp2-hybridized carbon in the coating, the contact resistance of the coating decreased. Moreover, the interfacial contact resistance was 3.1 mΩ·cm2 in the Ti-2 sample, much lower than that of bare 316L stainless steel. After the potentiostatic polarization test, the coating still had excellent conductivity.

Electrophoretic deposition, microstructure and selected properties of zein/cloves coatings on 316L stainless steel

In the present study, we develop zein coatings containing cloves (flower buds of the Syzygium aromaticum tree, a well-known aromatic natural herb) on stainless steel substrates via electrophoretic deposition. The antibacterial activity, drug release, surface (morphology, roughness, and wettability), corrosion, and adhesion properties of the produced zein/cloves coatings were elucidated in detail. The coatings deposited an applied electric field of 20 V/cm with a deposition time of 5 min yielded uniform zein/cloves coatings with a thickness of ~9 μm, which was confirmed by scanning electron microscopy. Fourier transformation infrared spectroscopy analysis confirmed the presence of zein and cloves functional groups in the zein/cloves coatings. The results of tape tests exhibited that the adhesion between the coatings and the substrate was rated as ‘5B’ (Excellent) according to the ASTM-D3359 standard. The zein/cloves coatings exhibited an average roughness of 0.8 ± 0.05 and a contact angle of 60° ± 2°, making them appropriate for orthopedic applications. The antibacterial studies exhibited that the zein/cloves coatings developed zone of inhibition against Staphylococcus aureus and Escherichia coli, confirming the strong antibacterial potential of the coatings. UV–Vis Spectroscopy elucidated that after one week of immersion in phosphate buffer saline, ~65 % of eugenol was released from the zein/cloves coatings. Furthermore, the zein/cloves coatings improved the corrosion resistance by ~3 orders of magnitude compared to bare 316L stainless steel. Antimicrobial and drug release studies confirmed that the zein/cloves coatings can provide a targeted drug delivery system with a potent antimicrobial effect.

Mitigation of chloride driven stress corrosion cracking susceptibility of 316L austenitic stainless steel using plasma sprayed TiO2 coating

AbstractThe present study proposes a protective TiO2 coating against chloride driven stress corrosion cracking problem of 316L austenitic stainless steel. To test the performance of the proposed coating, the severe chloride‐based boiling magnesium chloride solution at 155 °C was chosen. For experimentation, the constant strain‐based U‐bend specimens were coated with TiO2 using atmospheric plasma spray method. The results indicated higher resistance by TiO2 coated specimens against stress corrosion cracking problem, while the bare specimens experienced severe damage in the boiling magnesium chloride solution under various strain loading configurations. The coating‐electrolyte system of TiO2 coated sample demonstrated over seven times higher resistance, eventually led to reduction in corrosion rate over fifteen times compared to the bare 316L stainless steel in the boiling magnesium chloride solution. This improved performance of the coated 316L stainless steel is attributed to inhibition of outward diffusion of iron‐chromium‐nickel in the corrosive environment and the high chemical stability of TiO2.

Sulfidation-Oxidation Resistance of Thermal Diffusion Multi-Layered Coatings on Steels.

The high-temperature sulfidation-oxidation corrosion resistance of protective coatings deposited on carbon and 316L steels was studied. The coatings obtained via the thermal diffusion process had multi-layered architectures and consisted of aluminides, iron borides, or iron boride–TiO2 layers. The protective coatings experienced a minimal rate of mass changes, insignificant scale formation, and no delamination and surface micro-cracking after 504 h of exposure in 1% (Vol.) H2S-air atmosphere at 500 °C. Furthermore, the coatings demonstrated a high degree of integrity compared to bare 316L stainless steel. Aluminized steels demonstrated the highest performance among the studied materials. The developed thermal diffusion coatings are promising candidates due to their enhanced stability in H2S–air atmosphere; they may be employed for protection of inner and outer surfaces of long tubing and complex shape components.

Corrosion-resistant, electrically conductive TiCN coatings for direct methanol fuel cell

To improve the resistance to corrosion attack, hydrophobicity and the electrical conductivity of stainless steel (SS) bipolar plates for usage in direct methanol fuel cells (DMFC), a TiCN nanostructured coating, with the average thickness about 15 μm, was deposited onto a 316L SS substrate using the double cathode glow discharge plasma (DCGDP) method. Electrochemical measurements were carried out at 50 °C to determine the corrosion performance of both bare and TiCN-coated 316L SS in a simulated anode environment, replicating the operating conditions of a DMFC, with different methanol concentrations (0.05 M H2SO4 + 2 ppm HF + x M methanol (where x = 5, 10, 15, 20)). The results showed that the electrochemical degradation rate of both materials decreased with increasing methanol addition due to the restriction of proton mobility in the solution through the action of the methanol. At all the methanol concentrations of the test solutions, the TiCN coating had higher corrosion potentials and lower corrosion current densities than bare 316L SS, thus showing better corrosion resistance and enhanced electrochemical stability. Moreover, interfacial contact resistance (ICR) measurements revealed that the TiCN coating immersed in all test solutions with different methanol concentrations maintained a very low ICR value, which was advantageous to the operation of DMFC. Therefore, the TiCN coating, combining excellent corrosion resistance with good electrical conductivity, is considered to be an attractive candidate to serve as a protective surface for SS bipolar plates.

Electrochemical and hydrogen evolution behaviour of a novel nano-cobalt/nano-chitosan composite coating on a surgical 316L stainless steel alloy as an implant

Herein, nanocomposite coatings consisting of chitosan (CSNPs) and cobalt nanoparticles (CoNPs) were deposited on bare 316L stainless steel alloy (316L SS) as a bone implant. Scanning electron microscope (SEM) and energy dispersive X-ray (EDX) were applied to characterize the morphological and chemical composition of the tested nanocoatings. In-vitro degradation and hydrogen evolution behaviour of the coated samples were examined by means of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques, in Hank's solution containing of 1 × 10−3 M calcium hydrogen phosphate drug at pH 7.4 and temperature 37 °C. This drug used as an inhibitor for protecting the alloy surface from the corrosive medium and minimized the hydrogen evolution rate. Results showed that the di-phasic coating (CoNPs-CSNPs) gave the highest electrochemical corrosion resistance with the lowest hydrogen evolution rate in comparison to the monophasic coatings (CS-NPs & Co-NPs). These corrosion results suggested that a CoNPs-CSNPs nanocomposite coating on 316L SS was effective for renewable or functional implants.

Improvement in the surface properties of stainless steel via zein/hydroxyapatite composite coatings for biomedical applications

Although stainless steel is renowned for its wide use as a biomaterial, but relatively higher corrosion rate in physiological environment restricts its clinical applications. To overcome the corrosion resistance of stainless steel bio-implants in physiological environment and to improve the osseointegration behavior we developed zein/hydroxyapatite (HA) composite coatings deposited on stainless steel substrate by Electrophoretic Deposition (EPD). The EPD parameters were optimized using the Taguchi Design of Experiment (DoE) approach. The EPD parameters such as the concentration of bio-ceramic particles in the polymer solution, applied voltage, and deposition time were optimized on stainless steel substrates by applying mixed design orthogonal Taguchi array. The coatings were characterized by using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and wettability studies. SEM images and EDX results indicated that zein/HA coating was successfully deposited on stainless steel substrates. The wettability and roughness studies elucidated the mild hydrophilic nature of the zein/HA coatings, which confirmed the suitability of the developed coatings for biomedical applications. Zein/HA coatings improved the corrosion resistance of bare 316L stainless steel. Moreover, zein/HA coatings showed suitable adhesion with the 316L SS substrate for biomedical applications. Zein/HA coatings developed dense HA crystal upon immersion in simulated body fluid, which confirmed the bone binding ability of the coatings. Thus, the zein/HA coatings presented strong potential to be considered for orthopedic applications.

Effect of N+ Implantation on Surface Characteristics of 316L Stainless Steels for Bipolar Plate in PEMFC

Nitrogen was implanted into 316L stainless steel by plasma immersion ion implantation (PIII) for surface modification. Due to nitrogen implantation, the corrosion resistance and interfacial contact resistance (ICR) were improved compared to the bare 316L stainless steel. The improved corrosion resistance was attributed to the formation of the expanded austenite phase (γN). The phase formation was found to be closely related to the evolution of the (111) plane texture. The formation of γN is strongly related to applied bias voltages. When bias voltages were increased to 15 kV, the γN phase was partially decomposed due to the formation of excessive nitride, including the CrN phase. For the ICR, increased crystallite size is effective in reducing contact resistance, which might arise from a reduced number of the grain boundary with electron scattering. In particular, the applied bias voltage of 10 kV was the most effective to both corrosion resistance and ICR, and its performance satisfies the demand for a bipolar plate in the Polymer Electrolyte Membrane Fuel Cells (PEMFC).

Fabrication and Characterization of Zein/Hydroxyapatite Composite Coatings for Biomedical Applications

Stainless steel is renowned for its wide use as a biomaterial, but its relatively high corrosion rate in physiological environments restricts many of its clinical applications. To overcome the corrosion resistance of stainless steel bio-implants in physiological environments and to improve its osseointegration behavior, we have developed a unique zein/hydroxyapatite (HA) composite coating on a stainless steel substrate by Electrophoretic Deposition (EPD). The EPD parameters were optimized using the Taguchi Design of experiments (DoE) approach. The EPD parameters, such as the concentration of bio-ceramic particles in the polymer solution, applied voltage and deposition time were optimized on stainless steel substrates by applying a mixed design orthogonal Taguchi array. The coatings were characterized by using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and wettability studies. SEM images and EDX results indicated that the zein/HA coating was successfully deposited onto the stainless steel substrates. The wettability and roughness studies elucidated the mildly hydrophilic nature of the zein/HA coatings, which confirmed the suitability of the developed coatings for biomedical applications. Zein/HA coatings improved the corrosion resistance of bare 316L stainless steel. Moreover, zein/HA coatings showed strong adhesion with the 316L SS substrate for biomedical applications. Zein/HA developed dense HA crystals upon immersion in simulated body fluid, which confirmed the bone binding ability of the coatings. Thus the zein/HA coatings presented in this study have a strong potential to be considered for orthopedic applications.

Effect of Al content on the corrosion resistance and conductivity of metal nitride coating in the cathode environment of PEMFCs

In this paper, TiN coatings doped with various Al contents are settled on stainless steel 316L (SS316L) as bipolar plates of proton exchange membrane fuel cells (PEMFCs) through closed field unbalanced magnetron sputter ion planting. The influence of Al doping on the phase structure, surface morphology, corrosion resistance, passive film, interfacial contact resistance (ICR) and contact angle are studied. According to results of X-ray diffraction (XRD), the TiAlN coated samples have grain refinement. From the results of scanning electron microscope (SEM), TiAlN coatings are dense and uniform. Based on the potentiodynamic polarization test results, TiAlN-2A coating exhibits the highest corrosion potential of 0.17 VSCE and the lowest corrosion current density of 1.42×10−7 A cm−2 in the simulated PEMFCs cathode environment, which completely meets the DOE 2020 technical targets (<1×10−6 A cm−2), as well as the best stability and the lowest current density in the cathode potentiostatic polarization test. In addition, the electrochemical impedance spectroscopy (EIS) test reveals that TiAlN-2A coating has the highest corrosion resistance than bare SS316L and the rest coatings. Capacitance analysis shows that TiAlN-2A coated sample has lower electron donor concentration, which indicates better corrosion resistance. According to ICR results, at compaction of 1.4 MPa, the ICR value of TiAlN-2A coating is 12.6 mΩ cm2, which is close to satisfy the DOE 2020 technical targets (≤10 mΩ cm2). In addition, the corrosion and conductivity mechanism is also investigated.

Characterization of PTFE Film on 316L Stainless Steel Deposited through Spin Coating and Its Anticorrosion Performance in Multi Acidic Mediums.

Polytetrafluoroethylene (PTFE) was coated on 316L stainless steel (SS) substrate through a spin coating technique to enhance its corrosion resistance properties in hydrochloric acid (HCl) and nitric acid (HNO3) medium. Scanning electron microscopy (SEM) revealed the morphology of the coated and uncoated substrates and showed a uniform and crack-free PTFE coating on 316L SS substrate, while a damaged surface with thick corrosive layers was observed after the electrochemical test on the uncoated sample. However, an increased concentration of HCl and HNO3 slightly affected the surface morphology by covering the corrosive pits. An atomic force microscope (AFM) showed that the average surface roughness on 316L SS and PTFE coating was 26.3 nm and 24.1 nm, respectively. Energy dispersive X-ray spectroscopy (EDS) was used for the compositional analysis, which confirmed the presence of PTFE coating. The micro Vickers hardness test was used to estimate the hardness of 316L SS and PTFE-coated substrate, while the scratch test was used to study the adhesion properties of PTFE coating on 316L SS. The anticorrosion measurements of 316L SS and PTFE-coated substrates were made in various HCl and HNO3 solutions by using the electrochemical corrosion test. A comparison of the corrosion performance of PTFE-coated substrate with that of bare 316L SS substrate in HCl medium showed a protection efficiency (PE) of 96.7%, and in the case of HNO3 medium, the PE was 99.02%, by slightly shifting the corrosion potential of the coated sample towards the anodic direction.

Enhanced protective properties of hydrothermally synthesized Ni(OH)2-YSZ/reduced graphene oxide (rGO) nanocomposite coating

The hydrothermally synthesized Ni(OH)2-YSZ composite reinforced with reduced graphene oxide (rGO), was applied for corrosion protection of 316L stainless steel (SS) by electrophoretic deposition. The effect of rGO introduction on corrosion properties of Ni(OH)2-YSZ coating was investigated. The morphology and structures were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The corrosion properties of specimens were determined by Tafel polarization and electrochemical impedance spectroscopy (EIS) analysis in 3.5 wt% NaCl corrosive solution. The results showed that the corrosion protection properties were remarkably improved by the introduction of rGO into Ni(OH)2-YSZ composite film. The Ni(OH)2-YSZ/rGO coated SS showed a higher charge transfer resistance (1.85 × 105 Ω cm2) compared to Ni(OH)2-YSZ coated SS (6.12 × 104 Ω cm2) and bare 316L SS (4.55 × 104 Ω cm2). The addition of rGO to Ni(OH)2-YSZ composites efficaciously improved the dispersion of nanoparticles and also reduced their size. Consequently, the electrochemical enhancement caused by rGO introduction was attributed to the nano-sized particles, compaction, and uniformity of the coating, which efficiently prevented the steel substrate from corrosion attack.

A bilayer GO/nanofibrous biocomposite coating to enhance 316L stainless steel corrosion performance

A bilayer coating has been synthesized to be coated on the 316L stainless steel (SS) for bone implant application. The first layer consisted of graphene oxide (GO) which was coated via the electrophoretic deposition method. The second layer including Poly (ε-caprolactone) (PCL)/Gelatin-forsterite nanofibers was electrospun on the first layer. The morphology of the bare 316L SS, GO-coated, electrospun nanofibers, and nanofibers-coated samples were investigated using scanning electron microscopy (SEM). The electrospun nanofibers were also characterized by Fourier transform infrared spectroscopy (FTIR) and confirmed the presence of PCL, gelatin, and forsterite in the nanocomposite coating. Furthermore, the morphological investigation of the nanofibers revealed that 80:20 weight of PCL to gelatin did not show any beads, making them for coating on the GO coatings. In addition, the corrosion behavior of the coated samples was assessed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The samples coated with GO and GO/PCL-gelatin-forsterite 1% showed the best corrosion resistance in comparison with other samples. Consequently, the prepared bilayer biocomposite coating including 1 wt% forsterite nanoparticles can be a promising candidate for orthopedic implants.

Corrosion resistance and photocatalytic activity evaluation of electrophoretically deposited TiO2-rGO nanocomposite on 316L stainless steel substrate

Abstract TiO2-rGO nanocomposite coatings were obtained by electrophoretic deposition (EPD) technique of TiO2 nanoparticles and graphene oxide (GO) on stainless steel substrate. First, GO particles were synthesized using a modified Hummers' method. GO was reduced electrochemically to form a coating in the presence of nano-sized TiO2 particles. The influences of different parameters such as GO concentration, coupling co-electro-deposition parameters (electrophoretic duration and voltage) on thickness, surface morphology and, corrosion behavior of the as-synthesized TiO2-rGO nanocomposite coatings were systematically surveyed. The morphology and microstructure were investigated by field emission scanning electron microscopy (FE-SEM), Raman spectra and X-ray diffraction (XRD) techniques. Atomic force microscopy (AFM) was harnessed to evaluate the topography of the as-prepared GO powder. The bonding characteristics of as-synthesized and as-reduced GO were examined after deposition, by Energy Dispersive Analysis of X-Ray (EDX) and Fourier-transform infrared spectroscopy (FT-IR). Corrosion behavior of coatings and that of the pure TiO2 layer were evaluated by electrochemical impedance spectroscopy (EIS) and polarization techniques (by applying potentiodynamic polarization spectroscopy (PDS)). Detailed SEM studies showed that increasing EPD voltage brings about a coating with increased porosity and microcracks with higher thickness. In addition to that, the presence of rGO reduced corrosion current density (icorr) and shifted corrosion potential (Ecorr) toward more noble values in 3.5% NaCl at room temperature. Also, Analyses revealed that the optimum electrophoretically synthesized coating was obtained at GO concentration of 1 g/L, 30 V and 30 min at room temperature. The corrosion current density of the corresponding coating was remediated up to 0.2 μA cm−2, which means an anti-corrosion ability of about 30 times compared to TiO2-coated and bare 316L stainless steel. The results of impedance spectroscopic studies demonstrated that this coating renders as a barrier layer and resistance increased from 2.95 KΩ cm2 for TiO2-coated layer to 10.49 KΩ cm2 for the optimized layer.

Effect of Incorporating MoS2 in Organic Coatings on the Corrosion Resistance of 316L Stainless Steel in a 3.5% NaCl Solution

This study discusses a new coating method to protect 316L stainless steel (SS) from pitting corrosion in high chloride environments. The SS surface was coated using a simple, eco-friendly method, and sunflower oil (SunFO) was used as a base coating and binder for molybdenum disulfide (MoS2). The coated surface was observed using scanning electron microscopy (SEM) with an energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). Corrosion behavior was examined by open-circuit potential (OCP) measurement and electrochemical impedance spectroscopy (EIS) in an 3.5% NaCl solution. The SunFO coating with MoS2 showed the highest corrosion resistance and coating durability during the immersion time relative to the SunFO coating and bare 316L SS. The increased corrosion resistance is thought to be because of the interactions with the aggregations of the SunFO lamellar structure and MoS2 in the coating film, which acted as a high order layer barrier providing protection from the metals to electrolytes.

Electrophoretic deposition of lawsone loaded bioactive glass (BG)/chitosan composite on polyetheretherketone (PEEK)/BG layers as antibacterial and bioactive coating.

In this study, chitosan/bioactive glass (BG)/lawsone coatings were deposited by electrophoretic deposition (EPD) on polyetheretherketone (PEEK)/BG layers (previously deposited by EPD on 316-L stainless steel) to produce bioactive and antibacterial coatings. First, the EPD of chitosan/BG/lawsone was optimized on stainless steel in terms of suspension stability, homogeneity and thickness of coatings. Subsequently, the optimized EPD parameters were used to produce bioresorbable chitosan/bioactive glass (BG)/lawsone coatings on PEEK/BG layers. The produced layered coatings were characterized in terms of composition, microstructure, corrosion resistance, in vitro bioactivity, drug release kinetics and antibacterial activity. Ultraviolet/Visible (UV/VIS) spectroscopic analyses confirmed the release of lawsone from the coatings. Moreover, the deposition of chitosan/BG coatings was confirmed by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared spectroscopy (FTIR). The coated specimens presented higher corrosion resistance (10 times) in comparison to that of bare 316-L stainless steel and showed convenient wettability for initial protein attachment. The presence of lawsone in the top layer provided antibacterial effects against Staphylococcus carnosus. Moreover, the developed coatings formed apatite-like crystals upon immersion in simulated body fluid, indicating the possibility of achieving close interaction between the coating surface and bone. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 3111-3122, 2018.