Bare Stainless Steel Research Articles

Solar-Thermal Performance of Sparked Stainless Steel-based Solar Absorber under Solar Concentration

Solar absorbers are indispensable components in concentrated solar-thermal (CST) energy systems. Material selection is crucial in optimizing the performance of these systems. Traditional fabrication methods for solar absorbers often rely on chemical processes, which can be both costly and environmentally detrimental. This study presents the first investigation of the solar-thermal performance of a stainless steel absorber fabricated through a non-chemical sparking process in a tip-substrate configuration. Stainless steel, recognized for its cost-effectiveness and high-temperature thermal stability, emerges as a promising candidate for solar absorber applications. The sparked stainless steel exhibited enhanced solar absorptivity of 84.0% and thermal emissivity of 47.3%, representing increases of approximately 33% and 13.7%, respectively, compared to bare stainless steel. Raman spectroscopy and atomic force microscopy confirmed the formation of a random nanotexture of magnetite on the sparked surface, contributing to the improved optical properties. The solar-thermal performance of the sparked stainless steel is maximized at 84.0% when the absorber temperature aligns with the ambient temperature or under conditions of extreme optical concentration. To maintain a solar-thermal performance exceeding 70% at elevated absorber temperatures of 150 °C, 250 °C, 350 °C, and 450 °C, optical concentrations of 5, 13, 28, and 52, respectively, are required.

Enhancing puncture resistance in critical applications: A combined experimental and numerical approach

The qualification of materials for puncture resistance is essential for applications like pressure vessels and transport containers, particularly for the safe transport of radioactive materials. International regulations, set forth by organizations such as the International Atomic Energy Agency (IAEA) and the Atomic Energy Regulatory Commission (AERB), mandate the design of transport packages capable of withstanding various accident scenarios, including puncture, fire, impact, and immersion, to ensure the safety and integrity of radioactive material transport. This paper establishes a correlation between puncture energy ( E) required to penetrate stainless steel and mild steel plates, both with and without lead backing, as a function of plate thickness ( t) and punch diameter ( d). The simulation of strain and damage caused by punch impact is carried out within the elastoplastic region of structural materials, with a focus on the kinetic strengthening of the material. Abaqus finite element software is employed for numerical simulations, with model parameters derived from experimental stress-strain flow curve data using a curve-fitting technique. Dynamic compression experiments were conducted at the Refueling Technology Division (RTD) in the Bhabha Atomic Research Center (BARC) across a range of strain rates from 600 [Formula: see text] to 1750 [Formula: see text] at room temperature, using a Split Hopkinson Pressure bar. Additionally, drop weight tower (DWT) experiments were performed at RTD in the BARC facility to calibrate numerical simulations. These experiments were carried out on both bare and leaded stainless steel (SS304L) and mild steel (SA516Gr70) plates.

Intermittent polarity inversion of stainless-steel paired electrodes for efficient and durable water electrolysis

Designing robust and cost-effective catalysts through straightforward and replicable techniques is crucial for advancing water electrolysis. In this study, we introduce a dynamic polarization control method for the continuous activation of stainless steel (SS) substrates to achieve high water-splitting performance and durability. By applying periodic inverted current density during high–current–density operation (0.5 or 1 A cm−2) on bare SS adopted as both cathode and anode substrates, a NiFe-based oxide structure favorable for the hydrogen evolution reaction is formed at the cathode, while a Fe-incorporated NiOOH structure with high efficacy for the oxygen evolution reaction develops at the anode. Implemented in an anion exchange membrane water electrolysis system, this inverted polarization approach applied for the SS paired electrolyzer system successfully maintains a cell voltage of approximately 1.9 V for 500 h at a current density of 1 A cm−2 using bare SS for both electrodes.

Effect of optical stimulation temperature on the TA-OSL background and signal

The impact of readout temperature on background during optically stimulated luminescence (OSL) measurement is reported in this study. The background signal on un-irradiated phosphors has been found to increase significantly with readout temperature for the samples studied in this work, Al2O3:C and CaSO4:Dy. This increase in background signal with rising stimulation temperature on un-irradiated phosphors may overlap with the thermally assisted OSL (TA-OSL) signal. This phenomenon was observed only in the case of phosphors and not with bare stainless steel (SS) discs/planchets, and hence, this background emission should not be confused with blackbody radiation. Moreover, the reported background emission was seen to be much larger than the blackbody radiation. Although the TA-OSL signal does increase with temperature, it does not increase proportionally to the background signal. Therefore, to determine the net increase in TA-OSL due to the rise in readout temperature, the increase in background signal should be taken into consideration.

Deposition of TiO2/Polymethylene Biguanide on Stainless Steel Wire for the Enhancement of Corrosion Resistance and Stability

Background: Orthodontic treatment relies on stainless steel (SS) wires to apply forces and torque to reposition teeth. However, SS wires are susceptible to wear and corrosion in the oral environment, necessitating improvements in their durability. Objective: This study explores the potential of a coating comprising titanium dioxide (TiO2) and polymethylene biguanide (PHMB) to enhance the corrosion resistance of SS wires. Methods: SS wires were coated with a solution containing PHMB and TiO2 using a drop-casting technique. Field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDAX), and electrochemical tests, including impedance spectroscopy and potentiodynamic polarization, were conducted to characterize the coated wires and evaluate their corrosion resistance. Results: FE-SEM, EDAX, and Emap analysis confirmed the presence and uniform deposition of PHMB/TiO2 onto the SS wire surface. Electrochemical tests revealed that the PHMB/TiO2- coated SS wires exhibited a significantly lower corrosion rate (7.08×10−6 mm/year) and higher corrosion resistance (562466 Ω) compared to bare SS. Conclusion: The PHMB/TiO2 coated SS wire exhibited high corrosion resistance and offered potential benefits for orthodontic treatments. Further research and optimization of this coating may help to improve the durability and reliability of orthodontic appliances.

Effect of nitrogen pressure on the microstructure, conductivity, and corrosion resistance of ZrN-coated stainless steel as bipolar plate for proton exchange membrane fuel cell

Zirconium nitride (ZrN) coatings were deposited on the stainless steel using multi-arc ion plating under varying nitrogen partial pressures (PN) ranging from 0.5 to 3.5 Pa. The effect of phase composition, microstructure, and surface morphology on the corrosion resistance and conductivity of the ZrN-coated stainless steel in a simulated proton exchange membrane fuel cell (PEMFC) cathode environment was systematically explored. XRD and TEM revealed that the columnar-structured ZrN coating mainly comprised the fcc-ZrN phase. The Zr3N4 phase was discovered near the substrate during coatings prepared at low nitrogen partial pressures. Surface defects were reduced at nitrogen partial pressures exceeding 2.5 Pa. The ZrN coating exhibited enhanced corrosion resistance and conductivity (ZrN-3.5, Ecorr = 0.307 V, Icorr = 2.085 × 10−7 A/cm2, Rct = 1.125 × 105 Ω·cm2) compared to bare stainless steel in the simulated PEMFC cathode environment. The presence of surface defects influenced the corrosion resistance, while differences in conductivity were related to the phase composition and microstructure of the coating. Thus, the findings indicate that ZrN coatings prepared under optimal deposition conditions can have potential applications in PEMFC bipolar plates.

The influence of low nitrogen doping on bacterial adhesion of sputtered a-C:H coatings

Heavily dependent on both surface and bacteria characteristics, multiple and complex parameters control bacterial adhesion to any biomaterial surface. That's why there are so many contradictory results regarding the antibacterial and adhesion inhibition properties of Diamond-Like Carbon (DLC) protective coatings, despite the well-established biocompatibility of this very broad group of materials. Aiming at Orthodontics, this study reports the modification of hydrogenated amorphous carbon coatings (a-C:H), by nitrogen incorporation upon reactive magnetron sputtering. The effect of low N content up to 10 at.% on the microstructure and bacterial adhesion was studied. Despite the progressive graphitization upon doping, the surface roughness was not significantly influenced and the water contact angles remained above 70°. The adhesion of three bacterial strains of Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa was evaluated. The median colony forming units was lower on the a-C:H and a-C:H:N coatings in comparison to the bare AISI 316L medical grade stainless steel surface, regardless the bacterial strain. The best bacterial adhesion inhibition capacity was achieved for N doping of 6 at.%, without using any antibacterial agents.

Corrosion inhibition of stainless steel through the formation of hydrophobic nanoporous oxide layer

This study investigates anti-corrosion properties of anodized and hydrophobically modified anodized SUS 304 stainless steel (SS 304). Utilizing electrochemical anodization and subsequent annealing, a well-ordered hexagonally closed-packed nanoporous oxide layer on the SS 304 surface, designated as AAS, was successfully developed. Then, a self-assembled monolayer of silane molecules, namely, octadecyltrimethoxysilane (ODTS) and 1 H,1 H,2 H,2 H-perfluorooctyltriethoxysilane (PFTS), was formed on the nanoporous oxide layer of annealed-anodized SS 304. The FTIR study confirmed the formation of the self-assembly of silane molecules on nanoporous oxide surface. The self-assembled monolayers exhibited hydrophobic surface where hydrophobicity increases with increase of silane molecule concentration and gives a water contact angles measure of 127.60° and ∼ 128.83° for 0.50 wt% ODTS and 0.50 wt% PFTS, respectively. The potentiodynamic polarization study revealed a corrosion rate of 1.485 × 10−3 mm year−1 for AAS, 0.614 × 10−3 mm year−1 for 0.50 wt% ODTS-AAS, and 0.348 × 10−3 mm year−1 for 0.50 wt% PFTS-AAS. This represents a significant reduction in corrosion rate compared to bare stainless steel (4.385 × 10−3 mm year−1) when exposed to a simulated sea water environment. The AAS, 0.50 wt% ODTS-AAS and 0.50 wt% PFTS-AAS exhibited corrosion inhibition efficiency of 66.13 %, 85.97 % and 92.06 %, respectively. Electrochemical impedance analysis revealed that PFTS exhibits roughly double the effective charge transfer resistance of ODTS and 7.4 times higher than that of annealed anodized stainless steel, confirming superior corrosion inhibition capability. Overall, this research illuminates the mechanism behind self-assembled monolayer formation, resulting in the development of hydrophobic surfaces and the inhibition of corrosion on nanoporous oxide layers on stainless steel surfaces.

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.

Electrophoretic Deposition of 58S Bioactive Glass- Polymer Composite Coatings on 316L Stainless Steel: An Optimization for Corrosion, Bioactivity, and Cytocompatibility.

This study presents a facile fabrication of 58S bioactive glass (BG)-polymer composite coatings on a 316L stainless steel (SS) substrate using the electrophoretic deposition technique. The suspension characteristics and deposition kinetics of BG, along with three different polymers, namely ethylcellulose (EC), poly(acrylic acid) (PAA), and polyvinylpyrrolidone (PVP), have been utilized to fabricate the coatings. Among all coatings, 58S BG and EC polymers are selected as the final composite coating (EC6) owing to their homogeneity and good adhesion. EC6 coating exhibits a thickness of ∼18 μm and an average roughness of ∼2.5 μm. Herein, EC6 demonstrates better hydroxyapatite formation compared to PAA and PVP coatings in simulated body fluid-based mineralization studies for a period of 28 days. Corrosion studies of EC6 in phosphate-buffered saline further confirm the higher corrosion resistance properties after 14 days. In vitro cytocompatibility studies using human placental mesenchymal stem cells demonstrate an increase in cellular viability, attachment, and higher proliferation compared to the bare SS substrate. EC6 coatings promote osteogenic differentiation, which is confirmed via the upregulation of the OPN and OCN genes. Moreover, the EC6 sample exhibits improved antibacterial properties against Escherichia coli and Staphylococcus aureus compared to the uncoated ones. The findings of this work emphasize the potential of electrophoretically fabricated BG-EC composite coatings on SS substrates for orthopedic applications.

A new insight into the contact sliding and wear resistance of 2D/layered materials and their composites based on WS2 and multilayer graphene

While several coatings exist today to achieve tribological support on practical surfaces, the hunt for easily deployable yet tribological-efficient coatings still continues to fulfill the demand for commercial contact-sliding systems. Solution-based 2D/layered material coatings can be promising in this regard but many uncertainties remain to persist. Here we explored the tribological characteristics of solution-processed monolithic tungsten disulfide (WS2) and multilayer-graphene (mGR) coatings and simultaneously developed a new breed of WS2_mGR composite coating on stainless steel (SS) substrates. We discovered that monolithic WS2 coating (1 mg/ml) is tribologically inefficient even at its higher concentration (up to 5 mg/ml). The WS2_mGR composite coating demonstrated a remarkable reduction in friction and wear, with a 59% reduction in coefficient of friction (COF) compared to the Bare SS. Additionally, it demonstrated a 57% and 31% reduction in COF with respect to monolithic WS2 and mGR coatings, respectively, both prepared with the same concentration (1 mg/ml). Further, we also discovered that at higher concentrations (5 mg/ml) the monolithic mGR coating attains the lowest and most stable friction and high wear resistance over a longer period of time, even without the need for intermittent supply of lubricants during contact sliding.

Electrosprayed zein nanoparticles as antibacterial and anti-thrombotic coatings for ureteral stents

Ureteral stents are among the most frequently used human implants, with urothelium trauma, blood clots, and bacterial colonization being their main reasons for failure. In this study, berberine-loaded zein (ZB) nanoparticles with high drug encapsulation efficiency (>90 %) were fabricated via electrospray on flat and 3D stainless steel structures. Physico-chemical characterization revealed that the ZB nanoparticles created a highly hydrophilic, antioxidant, and scratch-resistant continuous coating over the metal structure. Results showed that the drug release rate was faster at neutral pH (i.e., PBS pH 7.4) than in an artificial urine medium (pH 5.3) due to the different swelling behavior of the zein polymeric matrix. In vitro evaluation of ZB particles onto human dermal fibroblasts and blood cells demonstrated good cell proliferation and enhanced anti-thrombotic properties compared to bare stainless steel. The ability of the electrosprayed zein particles to resist bacterial adherence and proliferation was evaluated with Gram-negative (Escherichia coli) bacteria, showing high inhibition rates (−29 % and −46 % for empty and berberine-loaded particles, respectively) compared to the medical-grade metal substrates. Overall, the proposed composite coating fulfilled the requirements for ureteral applications, and can advance the development of innovative biocompatible, biodegradable, and antibacterial coatings for drug-eluting stents.

Micromachining on Stainless Steel 304 for Improved Water Condensation Properties

Microstructure fabrication and chemical surface functionalization with low-surface-energy materials are the key steps to achieve hydrophobic surfaces with high water droplet contact angles (CA). In this work we employed wire Electric Discharge Machining (EDM) as a way to induce microstructure topography on stainless steel 304 coupons. The resulting topography was rendered hydrophobic using trichloro-1H,1H,2H,2H-perfluorooctyl silane (PFOTS) via gas phase deposition. The channels created by machining and PFOTS functionalization facilitate water condensation by increasing nucleation sites and enhancing droplet coalescence. The resulting surface is hydrophobic (CA~140o) in contrast to the bare stainless steel 304, which is hydrophilic (CA~76o).

Efficient integration of electrocoagulation treatment with the spray-pyrolyzed activated carbon coating on stainless steel electrodes for textile effluent-bath reuse with ease.

In this study, the electrocoagulation (EC) treatment was used to minimize and separate pollutants from textile industrial wastewater (TIWW), including high colour, chemical oxygen demand (COD), total organic carbon (TOC), and total dissolved solids (TDS). To enhance the EC treatment efficiency, a novel strategy has been followed in the study that involves thin-film coating on 316 stainless steel (SS) electrodes with banana peel-derived activated carbon (BPAC) by dip coating, spin coating, or spray coating. Among the different types of coating, thickness and contact angle measurements have elucidated that the spray coating of BPAC on SS electrode is the best tool with minimum thickness and contact angle. In this study, a bare SS electrode was used as the anode and a thin-film spray-coated BPAC on the SS electrode was used as the cathode. Moreover, optimization plays a key role in EC treatment process, where operating conditions such as a current density of 10 mA/cm2 , contact time of 15 min, and a pH of 7 were fixed. As a result, the findings indicate comparatively high colour removal of 98%, COD removal of 91%, TOC removal of 89.6%, and TDS removal of 68 % are achieved with ease. Accordingly, in comparison to plain SS electrodes or dip or spin-coated BPAC on SS electrodes, spray-coated BPAC on SS electrodes in EC treatment outperforms in removing high colour, TOC, COD, and TDS. Overall, the study highlights the potential of EC treatment integrated with adsorption procedures for TIWW treatment. Particularly, the use of thin-film spray-coated BPAC on SS electrodes in the EC treatment process led to an effective and sustainable tool for treating and reuse of TIWW. It is due to its low operation and maintenance cost and studied in a short interval of time. Finally, the ultimate goal was firmly achieved in pilot scale studies by the safe discharge into the environment or reuse of treated textile wastewater. Thus, it is a promising alternative with an environmentally friendly footprint that could be easily implemented in any textile industry premises.

Strengthening Stainless Steel Tubular Beams using Fibre-reinforced Concrete incorporating Sugarcane Bagasse Ash

Stainless steel tubular beam sections have been increasingly utilised for structural applications due to the enhanced properties of stainless steel over conventional mild steel. However, thin-walled stainless steel sections are not effectively used for several practical applications due to the higher costs and its response to easily undergo local buckling under flexural loading. Consequently, to overcome these effects, concrete infilling is a generally preferred strengthening mechanism that enhances the overall capacity and makes the sections economic. Earlier research studies on the flexural behaviour of various concrete-infilled stainless steel composite beam specimens are highly limited. Therefore, this study mainly focuses on the flexural behaviour of bare stainless steel tubular beams, sugarcane bagasse ash blended concrete-infilled stainless steel composite beam, and fibre-reinforced sugarcane bagasse ash blended concrete-infilled stainless steel composite beam. The study uses sugarcane bagasse ash as a pozzolan in the infill concrete to produce durable and sustainable concrete. In the same manner, crimped steel fibres are incorporated to enhance the ductility of the beam specimen. The parameters such as ultimate strength, maximum flexural deformation, initial stiffness, failure modes, ductility, and moment-rotation profiles were comprehensively investigated for all the beam specimens. Furthermore, numerical modelling was performed for the fibre-reinforced sugarcane bagasse ash blended concrete-infilled stainless steel composite beam specimen and was validated with the experimental results. It was witnessed that adding infill concrete to the stainless steel tube enhanced the beam specimens' load-carrying capacity, stiffness and ductility.

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.

Efficient Electrocatalytic Hydrogen Evolution Reaction on CuO Immobilized Stainless‐Steel Electrode Prepared by the SILAR Method

AbstractThe development of cost‐effective and efficient catalysts for the hydrogen evolution reaction (HER) has been a subject of intense research for sustainable and clean energy in recent decades. For this purpose, CuO‐modified stainless steel (CuO‐SS) electrode was fabricated to attain HER in acidic media. Here in, CuO film was fabricated on a stainless steel (SS) surface following successive ionic layer adsorption and reaction (SILAR) method. A 60‐cycle CuO modification resulted in enhanced HER activity compared to the bare SS or CuO electrode with an average 99 % Faradic efficiency. Based on the Electrochemical Impedance Spectroscopy (EIS), at an HER potential, the bare SS electrode exhibited charge transfer resistance of 24.7 Ω whereas CuO‐SS electrode exhibited 6.47 Ω only. The overpotential was calculated to be 154 mV at the CuO‐SS electrode regarding HER. The results have significant implications for the development of cost‐effective and efficient electrocatalysts for hydrogen production.

New reaction path for long-chain hydrocarbons by electrochemical CO2 and CO reduction over Au/stainless steel

The Fischer-Tropsch (F-T) synthesis is recognized for its ability to produce long-chain hydrocarbons. In this study, we aimed to replicate F-T synthesis using electrochemical CO2 reduction and CO reduction reactions on a stainless steel (SS) support with a gold (Au) overlayer. Under CO2-saturated conditions, the presence of Au on the SS surface led to the formation of CH4 and a range of hydrocarbons (CnH2n and CnH2n+2, n = 2–7), while bare SS primarily produced hydrogen. The Au(10 nm)/SS exhibited the highest hydrocarbon production in CO2-saturated phosphate, indicating a synergistic effect at the Au-SS interface. In CO-saturated conditions, bare SS also produced long-chain hydrocarbons, but increasing Au thickness resulted in decreased production due to poor CO adsorption. Hydrocarbons were formed through both direct and indirect CO adsorption pathways. Anderson-Schulz-Flory analysis confirmed surface CO hydrogenation and C–C coupling polymerization following conventional F-T synthesis. The C2 hydrocarbons exhibited distinct behavior compared to C3-5 hydrocarbons, suggesting different reaction pathways. Despite low reduction product levels, our EC method successfully replicated F-T synthesis using the Au/SS electrode, providing valuable insights into C–C coupling mechanisms and electrochemical production of long-chain hydrocarbons. Depth-profiling X-ray photoelectron spectroscopy revealed significant changes in surface elemental compositions before and after EC reduction.

Eco-Friendly Approach for the Construction of Superhydrophobic Coating on Stainless Steel Metal Based on Biological Metal-Organic Framework and Its Corrosion Resistance Performance.

In this paper, we present a sustainable approach for the creation of superhydrophobic (SP) coating on a stainless-steel substrate based on a biological metal-organic framework (MOF). The MOF was synthesized using aspartic acid as a linker and copper ions as a core metal. Two SP coatings were well constructed on stainless steel utilizing electrodeposition of nickel (Ni) and nickel altered by MOF (Ni@Bio-MOF) coatings followed by soaking in a solution of stearic acid in ethanol. The results of Fourier transform infrared spectroscopy demonstrate that the stearic acid-grafted nickel coating (Ni@SA) and the stearic acid-grafted Ni@Bio-MOF composite (Ni@Bio-MOF@SA), were effectively deposited on the stainless steel. The wettability findings displayed that the water contact angle of Ni@SA and Ni@Cu-As MOF@SA are 160° ± 1.1°, and 168° ± 1.2°, respectively. The prepared SP coating was also found to be chemically and mechanically stable. The results show that the Ni@SA coating maintains SP characteristics in a pH range of 3-11 while the Ni@Cu-As MOF@SA coating retained SP characteristics in a pH range of 1-13. Additionally, the superhydrophobic Ni@SA coating demonstrated SP characteristics up to a length of abrasion equal to 1300 mm, while the Ni@Cu-As MOF@SA coating exhibited SP characteristics up to a length of abrasion equal to 2700 mm. Furthermore, the Ni@SA and Ni@Cu-As MOF@SA coatings exhibited significantly improved corrosion protection in a 0.5 M NaCl solution compared with bare stainless steel, with protection efficiencies of approximately 94% and 99%, respectively. The results of this study demonstrate that the proposed approach is a promising method for the fabrication of eco-friendly and corrosion-resistant SP coatings on stainless steel substrate.

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.