Effects of temperature on corrosion performances of TiO2/SS316L in supercritical water for hydrogen production

Temperature is the most important factor for hydrogen generation during supercritical water gasification process. However, the increasing temperature could accelerate the corrosion of the reactor material, at the presence of oxygen, as less amount of oxygen can promote the hydrogen production. In this study, we prepared a 0.1 mm thick of TiO₂ coating on the surface of 316L stainless steel (SS316L) to enhance the corrosion resistance of SS316L during hydrogen production process in supercritical water. The influences of temperature (400–500 °C) on surface morphologies and corrosion depth and rate of TiO₂/SS316L were evaluated at 25 MPa with 1000 mg/L oxygen for 80h. Results showed that cracks and pores were present on the surface of TiO₂/SS316L after corroded in SCW for 80h. The crack width and corrosion rate was aggravated at higher temperature. The remained thickness of the coating at 400 °C, 450 °C, 500 °C were 0.08 mm, 0.05 mm and 0.03 mm, respectively. NiO and NiFe₂O₄ were generated around the crack on the surface of TiO₂/316L at 500 °C, the coating had a tendency to peel off the substrate.     

Comparative study on corrosion characteristics of Al2O3/316L and TiO2/316L stainless steel in supercritical water

Al₂O₃ and TiO₂ coatings were fabricated on 316L stainless steel by atmospheric plasma spraying to improve the corrosion resistance of 316L stainless steel in supercritical water. The corrosion characteristics of the samples were evaluated in a batch reactor at 500 °C and 25 MPa with an oxygen concentration of 1000 mg/L for 80 h. The adhesive strengths of the coated samples were tested, and the weight changes, morphologies and elements distributions of the fresh and corroded samples were analyzed. Results showed that the bond strength of TiO₂/316L was 1.5 times than that of Al₂O₃/316L (26.639 N/mm²). The surface morphology of Al₂O₃/316L showed gully erosion with much pores and cracks after exposed in SCW, which provided channels for oxygen and SCW to get into the substrate and also the elements in substrate to diffuse to the surface of the coating. The corroded Al₂O₃/316L suffered significant weight loss, and most of the coatings were peeled off. However, the surface morphology of TiO₂/316L was relatively dense and the thickness of the coating was not found to decrease obviously.     

Nanocomposite-carbon coated at low-temperature: A new coating material for metallic bipolar plates of polymer electrolyte membrane fuel cells

A nanocomposite-carbon layer is coated onto the surface of 316L stainless steel (SS316) using a beam of accelerated C₆₀ ions at low temperature. The coating is composed of textured graphite nanocrystals ranging in size from 1 to 2 nm, with the graphene plane normal to the coating plane; the nanocrystals are separated by amorphous carbon. This orientation of the graphene layer provides low film resistivity in the direction of the substrate normal. Corrosion resistance tests performed in aggressive anodic and cathodic environments of a polymer electrolyte membrane fuel cell (PEMFC) show that the nanocomposite-carbon coated SS316L exhibits better anticorrosion properties than does bare SS316L. The interfacial contact resistance (ICR) of the nanocomposite-carbon coated SS316L is 12 mΩ cm², which is similar to that of graphite at a compaction force of 150 N cm⁻² and lower than a target of ∼20 mΩ cm². A low value of ICR is maintained even after corrosion tests in aggressive anodic and cathodic environments. The fabricated nanocomposite-carbon coated SS316L exhibits excellent corrosion resistance and low interfacial contact resistance under simulated PEMFC bipolar plate conditions.     

Catalytic performances of Ni-based catalysts on supercritical water gasification of phenol solution and coal-gasification wastewater

Activity and stability of the supported Ni-based catalysts for the gasification performances of phenol solution and coal-gasification wastewater in supercritical water were studied in a continuous reactor at 480 °C, 25 MPa and oxygen ratio of 0.2 for 50 h operation. The influences of the supports (γ-Al₂O₃, active carbon (AC) and carbon nanotube (CNT)) on gas yields, gasification efficiencies for phenol solution were investigated, and the loading amount of Ni were optimized. Results showed that the catalytic activity and the stability of the catalysts followed the order of Ni/CNT > Ni/AC > Ni/γ-Al₂O₃. The activity of Ni/AC and Ni/γ-Al₂O₃ decreased after 30 h continuous operation, and there occurred significant leaching of Ni²⁺. For Ni/CNT catalyst, H₂ yield increased obviously when the loading amount of Ni lower than 15 wt%, while increased little at higher loading amount. Then, 15 wt% Ni/CNT with a thickness of 1.5 mm was coated on 316 L stainless steel (SS316L, an economic material usually used as the reactor material), which can act as a "catalytic tube wall" in reactor. The catalytic activity and corrosion resistance of Ni/CNT/SS316L for the gasification of real coal-gasification wastewater were studied. Results showed that Ni/CNT/SS316L gave a great positive effect on H₂ production. H₂ yield increased from 25.36 mmol/g (total organic carbon) without catalyst to 75.12 mmol/g (total organic carbon) with Ni/CNT/SS316L after operated for 20 h, respectively. However, obvious pealing of the coating was found after 50 h operation. Further study is necessary for the improvement of the coating preparation method.     

Evaluation of anticorrosion and contact resistance behavior of poly(orthophenylenediamine)- coated 316L SS bipolar plate for proton exchange membrane fuel cell

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 H₂SO₄ 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.     

Electrodeposition of conductive PAMT/PPY bilayer composite coatings on 316L stainless steel plate for PEMFC application

Stainless steel fulfills most of the requirements as bipolar plates in Proton Exchange Membrane Fuel Cell. However, it undergoes severe corrosion in fuel cell operating condition. This can be resolved by coating the stainless steel with corrosion resistive conducting polymers. In this study, homogeneous and adherent conductive Poly(2-amino-5-mercapto-1,3,4- thiadiazole)/Polypyrrole (PAMT/PPY) mono and bilayer polymer composite coatings are electrosynthesized on 316L SS in 0.5 M H₂SO₄ by cyclic voltammetry and chronopotentiometry. The hydrophobicity and surface morphology of the coatings are analyzed by contact angle and scanning electron microscopy respectively. The polymer coatings are evaluated in 0.5 M H₂SO₄ medium by potentiodynamic polarization and impedance techniques at 25 °C. The polarization results reveal that PAMT on PPY composite coating shifts the E_corr of the 316L SS towards noble direction. The EIS study reveals that the R_f value of PAMT on PPY coating is significantly higher by three orders (x10³ Ωcm²) of magnitude than uncoated 316L SS. The corrosion performance of the coatings in simulated PEMFC environment is investigated by potentiodynamic and potentiostatic studies. Results show that the PAMT on PPY and PPY on PAMT bilayer coatings are stable and increased the corrosion potential by about 410–470 mV and 275–310 mV (SCE) in simulated cathodic and anodic conditions respectively. This investigation reports that the PAMT on PPY bilayer coating is serving as a good physical barrier and protecting the 316L SS against corrosion in PEMFC environment.     

Coated stainless steels evaluation for bipolar plates in PEM water electrolysis conditions

Proton exchange membrane water electrolysis (PEMWE) is a promising technology to be incorporated in the production of green hydrogen, but one of its limitation to market penetration is the cost of bipolar plates (BPP).Aiming to reduce the cost of PEMWE stack, different surface engineered coating systems based on CrN/TiN, Ti/TiN, Ti and TiN deposited by physical vapor deposition on SS 316L, SS 904L and SS 321 were tested, as potential cost effective solutions to be implemented on bipolar plates. A corrosion evaluation has been carried out in anodic PEMWE conditions in order to determine the best substrate/coating combination for bipolar plates. Ti/TiN multi-layered coating on SS 321 shown the best performance with ?0.02% weight loss, current at 2 V_SHE to 436 μA cm^?2 and ICR after corrosion test to 9.9 mΩ cm².     

Durability and degradation of CrMoN coated SS316L in simulated PEMFCs environment: High potential polarization and electrochemical impedance spectroscopy (EIS)

The high potential on the cathode side originated from the start-up/shut-down processes is the one that cannot be ignored, which will accelerate degradation of the bipolar plates and increase the interfacial contact resistance (ICR) eventually degrade the performance of PEMFCs. Therefore, the coating with corrosion resistance and conductivity is in urgent need of development. CrMoN coating is deposited on SS316L by closed field unbalanced magnetron sputter ion plating (CFUMSIP) with an aim to improve corrosion resistance and conductivity of SS316L under PEMFCs at shut-up/shut-down stages. In terms of high potential polarization test, the corrosion current density and ICR values are found to increase as the applied potential increases. The electrochemical degradation of CrMoN coated SS316L is investigated by electrochemical impedance spectroscopy (EIS). After 40 days of immersion, the charge transfer resistance (R_ct) of the CrMoN-4A coated SS316L is approximately 14 times greater than that of the uncoated SS316L and the ICR values are 11.2 mΩ cm², indicating that the CrMoN-4A coating still has high corrosion resistance and well conductivity after long time immersion.     

Corrosion inhibition of methanol towards stainless steel bipolar plate for direct formic acid fuel cell

The corrosion properties of AISI316L stainless steel (316 L SS) as bipolar plates are investigated under aqueous acid methanol solutions (0.05 M H₂SO₄ + 2 ppm HF + 10 M HCOOH + x M CH₃OH (x = 0, 3, 6 and 9) solutions at 70 °C) to simulate the varied anodic operating conditions of direct formic acid fuel cells (DFAFCs). When the methanol content is higher, the potentiodynamic, potentiostatic polarisation and EIS tests of the 316 L SS bipolar plates all show excellent corrosion resistance. The surface morphology and the glow discharge mass spectrometer (GDMS) illustrate that the surface corrosion on 316 L SS bipolar plates is slowed down when the methanol concentration is increased. These results indicate the methanol plays the role in retarding the corrosion rate of the 316 L SS in simulated DFAFCs anodic operating conditions by restricting the proton conductivity in the test solutions. The sample tested in higher content methanol solution has smoother corroded surface and thinner passivation film, which contributes to a lower interfacial contact resistances (ICR) value.     

Corrosion behavior of SS316L in simulated and accelerated PEMFC environments

The electrochemical behavior and change in the passive film formation of SS316L are investigated under polymer electrolyte membrane fuel cell (PEMFC) simulated (pH from 3 to 6 containing F⁻, SO₄²⁻ and Cl⁻ anions) and accelerated conditions (0.5 M and 1 M H₂SO₄ + 2 ppm HF). Potentiodynamic, potentiostatic, and EIS measurements are performed to investigate the electrochemical behavior of the SS316L specimens in both the anode and cathode PEMFC environments. The chemical composition of the passive film, surface topography of the specimens, and degree of metal ion release is characterized by XPS, SEM, and ICP-OES, respectively. The results reveal that the nature of the passive film depends on the pH value, external medium/environment, as well as applied potential during polarization. The corrosion behavior of SS316L is closely related to the chemical composition and structure of the passive film.     

Corrosion properties and contact resistance of TiN, TiAlN and CrN coatings in simulated proton exchange membrane fuel cell environments

In this study, the contact resistance (CR) and electrochemical properties of TiN, CrN and TiAlN electron beam physical vapor deposition (EBPVD) coatings and their stainless steel 316L (SS316L) substrate were investigated in a simulated proton exchange membrane (PEM) fuel cell environment. The potentiodynamic polarization corrosion tests were conducted at 70 °C in 1 M H₂SO₄ purged with either O₂ or H₂, and the potentiostatic corrosion tests were performed under both simulated cathodic (+0.6 V vs. Ag/AgCl reference electrode purged with O₂) and anodic conditions (−0.1 V vs. Ag/AgCl reference electrode purged with H₂) for a long period (4 h). SEM was used to observe the surface morphologies of the samples after corrosion testing. All the TiN-, TiAlN- and CrN-coated SS316L showed a lower CR than the uncoated SS316L. While the corrosion performance of the coatings was dependent on the cathodic and anodic conditions, the CrN coating exhibited a higher (in the anodic environment) or similar (in the cathodic environment) corrosion resistance to the uncoated SS316L. Thus, the CrN-coated SS316L could potentially be used as a bipolar plate material in the PEM fuel cell environment. Although the EBPVD process greatly reduced number of pinholes in the coatings compared to other plasma enhanced reactive evaporations, future research efforts should be directed to eliminate the pinholes in the coatings for long-term durability in fuel cell applications.     

Activity and stability of TiO2 samples with different phase compositions in the decomposition of formaldehyde in SCW

TiO₂ samples with different crystal sizes and compositions were synthesized using a sol-gel method at different calcination temperatures (350–900 °C). The activity and stability of TiO₂ samples were determined by the gasification of formaldehyde in supercritical water (SCW) and by treatment in SCW. Increasing calcination temperature and SCW gasification (SCWG)/SCW treatment decreased the surface area of anatase TiO₂ samples due to growing crystallite size via agglomeration and sintering. Among anatase TiO₂ samples, the TiO₂ calcinated at 450 °C was found as the most suitable material under SCW conditions. However, the surface area of rutile TiO₂ slightly increased from 17.2 m² g^?1 to 19.8 m² g^?1 with the weakly crumbling of particles during SCWG. The highest hydrogen formation (63%) from formaldehyde in the SCW was obtained in the presence of anatase TiO₂ calcined at 350 °C and rutile TiO₂ calcined at 800 °C. CO₂ formation in the presence of anatase TiO₂ is higher than rutile TiO₂ because of the presence of active lattice oxygen species (O^?, O^2?) based on O₂-TPD.     

Effect of sulfide on corrosion behavior of stainless steel 316SS and Hastelloy C276 in sub/supercritical water

Stainless steel 316SS and Hastelloy C276, as the representatives of iron-based and nickel-based alloy, respectively, were employed to explore the corrosion properties under reducing subcritical and supercritical water containing sulfide. Experiments were executed at a pressure of 25 MPa, temperatures of 350 °C–520 °C, and sulfur concentrations of 1000 and 5000 ppm for 80 h. An isothermal equilibrium phase diagram involving the oxidation/sulfidation products of Fe, Cr, and Ni, was established by theoretical calculation in supercritical water system at 520 °C, in order to predict the corresponding products under various conditions and assist the discussion on corrosion mechanism. The results show that whether in subcritical water or in supercritical water, 316SS always exhibited better corrosion resistance relative to C276. In subcritical water at 350 °C, a portion of corrosion film peeled off from 316SS specimen, while numerous pores or cracks appeared on the surface of scale for C276. Under supercritical water at 520 °C, a compact scale grown on 316SS sample surface was composed of Fe₃O₄, FeCr₂O₄, and FeS. For C276, a duplex-layer scale formed on alloy surface. However, due to the higher content of Ni in C276, Ni-sulfide channels through the inner layer were developed, accelerating the sulfidation corrosion of alloys. Overall, the high-temperature alloys with high Cr content and low Ni/Cr ratio can be considered as the candidate material of equipment in supercritical water gasification of sulfur-containing coal.     

An investigation into the effects of a nano-thick gold interlayer on polypyrrole coatings on 316L stainless steel for the bipolar plates of PEM fuel cells

Polypyrrole is one of the most important conductive polymers because it is easily oxidized, water soluble and commercially available. Also, polypyrrole coatings have potential applications in batteries, fuel cells, electrochemical sensors, anti-corrosion coatings and drug delivery systems. In this study, a very thin gold layer was first coated on SS316L, and then a polypyrrole coating was laid on top. The nucleation and growth mechanisms of polypyrrole on the gold-coated SS316L were studied by electrochemical nucleation and growth techniques. SEM was used to characterize the polypyrrole coating morphology. Potentiodynamic tests were performed to determine the corrosion parameters of the polypyrrole coatings. Potentiostatic tests of the coated SS316L were conducted in simulated anode and cathode environments of a PEM fuel cell. The simulated anode environment was at a potential of about −0.1 V versus SCE purged with H₂ and the simulated cathode environment was at a potential of about 0.6 V versus SCE purged with O₂. After coating with Au and polypyrrole, the polarization resistance of SS316L is increased about six times, and the corrosion current density is decreased about seven times, compared to the base SS316L. Also, our calculations show that the metal ion concentration in solution for the polypyrrole/Au/SS316L had met the target of 10 ppm after 5000 h fuel cell operation.     

Long-term polarization accelerated degradation of nano-thin C/Ti coated SS316L bipolar plates used in polymer electrolyte membrane fuel cells

Dynamic potentials of polymer electrolyte membrane fuel cells (PEMFCs) lead to the corrosion of metal bipolar plates and significantly increase their interfacial contact resistance (ICR). Herein, two nano-thin C/Ti coatings with different thicknesses are prepared on SS316L (C/Ti/SS) and examined under three types of polarization potential modes. The C₁₀₀Ti₆₀ coating has improved corrosion resistance than C₂₀Ti₁₄₀ coating. The C₁₀₀Ti₆₀ coating exhibits a low ICR of 2.67 mΩ cm² and a small corrosion rate of 1.47 μA/cm², highlighting the high electrical conductivity and corrosion resistance. Moreover, C₁₀₀Ti₆₀/SS achieves a slight degradation of ICR after polarization at 0.67 V and cyclic polarization between 0.43 and 0.73 V. However, the high potential of 1.43 V induces severe delamination of C layer, resulting in a remarkable increase of ICR. Analysis suggests that the Ti layer improves the oxidation resistance and the C layer could provide effective protection when the potential is below 1.13 V.     

Corrosion characteristics of SS316L as bipolar plate material in PEMFC cathode environments with different acidities

The corrosion characteristics of SS316L in simulated proton exchange membrane fuel cell (PEMFC) environments with a wide range of H₂SO₄ concentrations have been systematically studied. Electrochemical methods, both potentiodynamic and potentiostatic, are employed to determine the corrosion parameters and the results show that corrosion resistance decreases with increasing H₂SO₄ concentrations. Scanning electron microscope (SEM) is used to examine the surface morphology of the specimens after potentiostatic polarized in simulated PEMFC cathode environments and the results indicate that local corrosion occurs under all the conditions studied and local corrosion is more severe with higher H₂SO₄ concentrations. Auger electron spectroscopy (AES) analysis is used to identify the composition and the depth profile of the passive film formed on the SS316L surface and the results show that the thickness of passive film decreases with increasing H₂SO₄ concentrations. Interfacial contact resistances (ICR) between SS316L polarized and carbon paper are measured and the results show that ICR decreases with increasing H₂SO₄ concentrations. The corrosion mechanisms of SS316L in PEMFC cathode environments are analysed and discussions on choosing simulated PEMFC cathode corrosion environments for accelerated tests are also provided.     

An investigation into nickel implanted 316L stainless steel as a bipolar plate for PEM fuel cell

A nickel-rich layer about 100 μm in thickness with improved conductivity was formed on the surface of austenitic stainless steel 316L (SS316L) by ion implantation. The effect of ion implantation on the corrosion behavior of SS316L was investigated in 0.5 M H₂SO₄ with 2 ppm HF solution at 80 °C by potentiodynamic test. In order to investigate the chemical stability of the ion implanted SS316L, the potentiostatic test was conducted in an accelerated cathode environment and the solutions after the potentiostatic test were analyzed by inductively coupled plasma atomic emission spectrometer (ICP-AES). The results of potentiodynamic test show that the corrosion potential of SS316L is shifted toward the positive direction from −0.3 V versus SCE to −0.05 V versus SCE in anode environment and the passivation current density at 0.6 V is reduced from 11.26 to 7.00 μA cm⁻² in the cathode environment with an ion implantation dose of 3 × 10¹⁷ ions cm⁻². The potentiostatic test results indicate that the nickel implanted SS316L has higher chemical stability in the accelerated cathode environment than the bare SS316L, due to the increased amount of metallic Ni in the passive layer. The ICP results are in agreement with the electrochemical test results that the bare SS316L has the highest dissolution rate in both cathode and anode environments and the Ni implantation markedly reduces the dissolution rate. A significant improvement of interfacial contact resistance (ICR) is achieved for the SS316L implanted with nickel as compared to the bare SS316L, which is attributed to the reduction in passive layer thickness caused by the nickel implantation. The ICR values for implanted specimens increase with increasing dose.     

An investigation into TiN-coated 316L stainless steel as a bipolar plate material for PEM fuel cells

In order to reduce the cost, weight and volume of the bipolar plates, considerable attention is being paid to developing metallic bipolar plates to replace the non-porous graphite bipolar plates that are in current use. However, metals are prone to corrosion in the proton exchange membrane (PEM) fuel cell environments, which decreases the ionic conductivity of the membrane and lowers the overall performance of the fuel cells. In this study, TiN was coated on SS316L using a physical vapor deposition (PVD) technology (plasma enhanced reactive evaporation) to increase the corrosion resistance of the base SS316L. X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical methods were used to characterize the TiN-coated SS316L. XRD showed that the TiN coating had a face-centered-cubic (fcc) structure. Potentiodynamic tests and electrochemical impedance tests showed that the corrosion resistance of SS316L was significantly increased in 0.5 M H₂SO₄ at 70 °C by coating with TiN. In order to investigate the suitability of these coated materials as cathodes and anodes in a PEMFC, potentiostatic tests were conducted under both simulated cathode and anode conditions. The simulated anode environment was −0.1 V versus SCE purged with H₂ and the simulated cathode environment was 0.6 V versus SCE purged with O₂. In the simulated anode conditions, the corrosion current of TiN-coated SS316L is −4 × 10⁻⁵ A cm⁻², which is lower than that of the uncoated SS316L (about −1 × 10⁻⁶ A cm⁻²). In the simulated cathode conditions, the corrosion current of TiN-coated SS316L is increased to 2.5 × 10⁻⁵ A cm⁻², which is higher than that of the uncoated SS316L (about 5 × 10⁻⁶ A cm⁻²). This is because pitting corrosion had taken place on the TiN-coated specimen.     

Electrochemical analysis on the growth of oxide formed on stainless steels in molten carbonate at 650 °C

The oxide growth on stainless steel (SS) 310S and 316L, used as a cathode current collector material of molten carbonate fuel cell (MCFC), were examined in the mixture of 62 mol% Li₂CO₃–38 mol% K₂CO₃ at 650 °C by measuring the change in corrosion potential and potentiodynamic response of the alloys and also in terms of impedance analysis on the alloy|oxide layer|electrolyte system. The corrosion potential of SS 316L was in an active region for 12 h-immersion, whereas that of SS 310S drastically increased after 6 h-immersion due to an active to passive transition. The corrosion rate of the two SSs decreased with immersion due to the growth of protective oxide. However, the decrease in the corrosion rate of SS 310S is much greater than that of SS 316L. The oxide formed on the two SSs was found to be duplex layer, composed of inner Cr enriched oxide and outer Fe enriched oxide. However, the inner Cr enriched layer of 310S is more clearly separated from the outer Fe enriched layer than that of SS 316L due primarily to the higher Cr content in SS 310S. The drastic increase in the corrosion potential of SS 310S after 6 h-immersion is closely associated with the growth of the inner Cr enriched oxide layer. The corrosion resistance of SS depends dominantly on the resistance of the inner Cr enriched oxide that is determined form the impedance analysis on the alloy|oxide layer|electrolyte system. The higher corrosion resistance of SS 310S compared with SS 316L results from the more protective inner Cr enriched oxide layer, as confirmed by its higher resistance associated with the higher Cr content in SS 310S.     

Investigation of incorporating oxygen into TiN coating to resist high potential effects on PEMFC bipolar plates in vehicle applications

During actual vehicle applications, the condition of start-up/shut-down generates high cathodic potential, causing the anodic dissolution and having a great impact on the lifetime of proton exchange membrane fuel cell (PEMFC). In order to improve the durability of the bipolar plate at high potential, the present work investigated the oxygen-doped TiN coating deposited on the surface of SS316L matrix. The results of X-ray photoelectron spectroscopy and X-ray diffraction showed that TiNO and TiO₂ existed in oxygen-doped coatings. The surface morphology analysis indicated that the oxygen-doped coatings tended to come into being denser surface. Besides, the tested results of potentiodynamic polarization, triangle wave high potential cyclic polarization, the electrochemical impedance spectrum and water contact angle test revealed that the TiNO-7sccm specimen possessed the best corrosion resistance, durability and surface hydrophobicity. After a long-term polarization (+0.6 V_SCE), the TiNO-5sccm samples possessed the lowest interfacial contact resistance value of 19.8 mΩ cm².