Corrosion Resistance Of TiN Coatings Research Articles

Controlled Oxygen Incorporation in TiN Coatings via Heat Treatment for Applications in PEMFC Metallic Bipolar Plates

Improving the corrosion resistance while maintaining good electrical conductivity is of vital importance for the application of stainless steel in bipolar plates of polymer electrolyte membrane fuel cells (PEMFCs). Transition nitride coatings on steel surfaces, such as TiN, is considered as a possible solution. However, most coatings still fail to exhibit good corrosion resistance and high electrical conductivity simultaneously, especially after corrosion testing. This study prepares TiN on 316L stainless steel (SS) and conducts heat treatment on the TiN deposited samples at different temperatures. The corrosion behaviours of the prepared samples are investigated under the simulated working environments of fuel cell. Our results demonstrate that heat treatment at appropriate temperatures is an effective approach to improve the corrosion resistance of TiN coatings while maintaining a considerable electrical conductivity. The interfacial contact resistance (ICR) test results indicate that high temperature (450 °C) heat treatment has detrimental effect on the electrical conductivity of samples due to the formation of a thick oxide dominated layer, while samples heat treated at 300 °C only form graded layers with suitable oxide amount which endows the coated specimens with a very low ICR value both before and after corrosion tests. This suggests that the heat treatment of TiN coatings under suitable conditions is a feasible strategy to simultaneously achieve an enhanced corrosion resistance and a good electrical conductivity of the TiN coated samples for bipolar plates in PEMFCs.

Protective nature of nano-TiN coatings shaped by EPD on Ti substrates

The hardness and corrosion resistance of TiN coatings, processed by Electrophoretic Deposition (EPD) to cover polished and unpolished Ti substrates, have been evaluated. A deposition time of 5min has been enough to obtain a cohesive layer of 7–8μm in thickness. The coatings were thermally treated in vacuum atmosphere at 1200°C for 1h with heating and cooling rates of 5°Cmin−1. The surfaces have been covered homogeneously optimizing the properties of the Ti substrates. Uniform and dense TiN coatings have been obtained onto polished substrates, while on unpolished Ti the nitrogen diffuses toward the substrate, moderately dissolving TiN coating. The nanohardness values of the polished samples have been increased from 2.8–4.8GPa up to 6.5–8.5GPa. Besides, the corrosion current density has been reduced more than one order of magnitude obtaining a protective efficiency of 82%. These values have been compared with other works in literature where authors used complex and costly processing techniques, demonstrating the strong impact of the colloidal processing over the specific properties of the material.

Corrosion resistance of tin coatings deposited by cold spraying

This article presents a study of corrosion resistance of tin and tin-based composite (Sn + Al2O3 and Sn + SiC) coatings deposited onto aluminium alloy substrates using the low-pressure cold spraying method. The samples were subjected to three different corrosion tests at a room temperature: (i) Kesternich test, (ii) a cyclic salt spray test and (iii) anodic polarisation test. The selected tests allowed extreme environment simulation typical for wide range of urban, industrial and marine service conditions. Evaluation of corrosion was carried out by analysing changes on the coating surface as well as in the microstructure. Additionally, the physicochemical tests were carried out using X-ray diffraction. XRD analysis clearly showed that abhurite Sn21O6Cl16(OH)14 is the main corrosion product established after the polarisation measurements. Despite extreme corrosive conditions used in experiments all tin coatings showed minor corrosion changes which implies that abhurite serves as a buffer between the metal and the oxidising natural environment.

The effect of TiN nanoparticles deposition with different number of shots on SS316L by plasma focus device

In this paper, we present the result of TiN nanocrystalline deposition on SS316L, using a 4 kJ plasma focus (PF) device for 10, 20, and 30 focus shots. The effect of different number of focus shots on micro-structural changes of thin film is characterized by field emission scanning electron microscope. Existence of grains in different size confirms the formation of TiN nanocrystals on the surface of SS316L substrate. X-ray diffraction (XRD) reveals the formation of a nanocrystalline titanium nitride coating on the surface of SS316L samples. The crystalline size of TiN obtained from XRD data is strongly dependent on the number of focus shots. Thickness of the elements found on the surface of the treated sample that obtain by Rutherford backscattering spectroscopy (RBS) analysis is in the range of 150×1015−200×1015 atoms/cm2. All the existence elements in the coated samples are identified by Particle Induced X-ray Emission (PIXE) spectra. Investigation on the corrosion resistance of TiN coatings was performed using an electrochemical potentiodynamic polarization. Our results suggest that TiN nanocrystalline implantation with proper ion fluences using PF can significantly improve the corrosion resistance of SS316L.

Corrosion Resistance of TiN Imitation Gold Decoration Coatings on Golden-Pen Components

Experiments were carried out with different process parameters to investigate the effects of used parameters on corrosion resistance of TiN coatings obtained. In experiments, TiN imitation gold decoration coatings were prepared on 1Cr13 pen-point and brass chromium plating pen-coil by multi-arc ion plating method. The phase composition of TiN coatings was measured by x-ray diffraction. The corrosion resistance of TiN coatings was tested by salt-mist and artificial-sweat experiments. The relationship between corrosion resistance of coatings and process parameters were analyzed. Therefore, the optimum process parameters were achieved suitable for plating coatings on substrates of 1Cr13 pen-point and brass chromium plating pen-coil with good imitation gold. Imitation gold plating layers obtained have good gloss, corrosion resistance, high hardness, wear resistance, and easy to maintain. The results showed that the corrosion resistance of coatings is more easily influenced by changes of PN2 and Vbom than that of matrix-bias voltage. The TiN coatings are of resistant to corrosion no matter they are in single or multi phase structure. The optimum parameters of achieving good corrosion resistance of TiN coatings are PN2=0.48Pa, Vbom=400V，bias=-20V. Under the optimum conditions, the obtained surface corrosion resistance state of the coatings can reach at least eight grades, even above ten grades.

Correlation between the surface characteristics and the duty cycle for the PACVD-derived TiN nanostructured films

In recent years, plasma-assisted chemical vapor deposition (PACVD) has been identified as a suitable technique to deposit hard coatings on tools of complex geometries. This study sheds light on the influence of the duty cycles on the surface characteristics of the nanostructured TiN coatings for the first time. A mixture of H 2, N 2, Ar, and TiCl 4 was used to deposit a thin film of TiN on the H13 steel. The micro-structural, mechanical, and tribological properties of the coating were investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Applying higher duty cycles resulted in formation of rougher surfaces. It was also revealed that the grain size increased with the duty cycle. Moreover, the film's thickness was measured as 1.6–2.3 μm, depending on this parameter. A hardness of 1723 HV 0.05 was obtained when the layer was fabricated at the lower duty cycles. Meanwhile, the corrosion resistance of TiN coatings grown under a low duty cycle was higher than that of the layers fabricated at higher duty cycles.

Investigation on Wear- and Corrosion Resistance of TiN Films by CVD

TiN films have been deposited on K211 super alloy substrates by chemical vapor deposition (CVD) using a gaseous mixture of TiCl4, NH3, and Ar as carrier gas between 400 and 700°C. The films were characterized by means of scanning electron microscopy and energy dispersive spectrometer. In this paper, the wear and corrosion resistance of TiN coatings have been investigated by abrasive experiments and corrosion tests. It was shown that coated samples demonstrated significantly higher wear resistance than those uncoated by weight loss measurements in the test procedure. Under the conditions of the corrosion experiments, substrates with TiN coatings showed better corrosion resistance than uncoated samples and stainless steel.

Study on the Properties of TiN Coatings on Previously Ion-Implanted Pure Magnesium Surface by MEVVA Ion Implantation

A metal vapor vacuum arc (MEVVA) is used in ion implantation for substrate preparation before the deposition process which would ensure the improvement of mechanical properties of the coating. Ti ion is implanted into pure magnesium surface by MEVVA implanter operated with a modified cathode. Implanting energy is kept at 45 keV and dose is set at 3 × 1017 cm-2. TiN coatings are deposited by magnetically filtered vacuum-arc plasma source on unimplanted and previously implanted substrates. Microstructure and phase composition are analysed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The property of corrosion resistance of TiN coatings was studied by CS300P electrochemistry-corrosion workstation, and the main impact factor of the corrosion resistance was also analyzed.

Properties of the TiN coatings on previously Ti ion-implanted magnesium alloy substrate

To enhance the mechanical properties of TiN coating on magnesium alloy, metal vapor vacuum arc (MEVVA) ion implantation was performed to modify magnesium alloy substrate before TiN film deposition. Implantation energy was fixed at 45 keV and dose was at 9 × 10 17 cm − 2 . TiN coatings were deposited by magnetically filtered vacuum-arc plasma source on unimplanted and implanted substrate. The microstructure composition distribution and phase structure were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The chemical states of some typical elements of the TiN coating were analyzed by means of X-ray photoelectron spectroscopy (XPS). The properties of corrosion resistance of TiN coatings were studied by CS300P electrochemical-corrosion workstation, and the mechanism of the corrosion resistance was also discussed.

Corrosion Resistance of High Hardness TiN Coatings Prepared by Gas Tunnel Type Plasma Reactive Spraying

Thick titanium nitride coatings, which have high hardness, were obtained by gas tunnel type plasma reactive spraying. In this study, the corrosion behavior of the thick TiN coatings was investigated using the electrochemical polarization measurement in 1 M hydrochloric (HCl) solution at room temperature of 295 K. The polarization curve of stainless steel (SUS304) was also measured in order to clarify the effect of corrosion resistance of TiN coatings on the substrates as protective layer. The results showed that the TiN coating could protect the substrate surface from corrosion. It also revealed that the corrosion resistance of TiN coatings was improved as the thickness of TiN coatings was increased.

The Correlation of Texture and Microstructure to the Corrosion Resistance of Tin Coatings

The influence of current density and temperature on the macrotexture, the orientation and size of grains, and the corrosion resistance of tin deposits was studied. Tin coatings with two different textures, (100) and (301) fiber textures were produced by electrodeposition at 20°C by varying current density. At a lower current density of 100A/m2, (301) fibre was obtained. At the current densities of 100 and up to 400 A/m2, only (100) fibre texture was observed. An increase in current density leads to a decrease in grain size. At the same current density, the grain size of tin coatings increases with increased temperature. The influence of temperature (20, 40, 60 and 80 °C) on texture is relatively negligible. The corrosion resistance of tin coatings increases with a decrease in grain size. The corrosion resistance of tin coating with (301) fibre is higher than that of tin coating with (100) fibre texture. The results suggest that texture and microstructure play an important role in controlling corrosion rate of tin based coatings.

Corrosion Resistance of TiN Coatings Prepared by Filtered Cathodic Vacuum Arc Process

ABSTRACTFor the purpose of developing the corrosion-resistant and low-cost metallic bipolar plates for direct methanol fuel cell (DMFC), Ti mesh, stainless steel and Si(100) were coated with TiN by using the filtered cathodic vacuum arc system (FCVA). These TiN films have received considerable attention because of its high anti-corrosion behavior and low contact-resistance. In order to improve the corrosion protective ability of TiN films and decrease pinholes of coating, growth modifications such as thickness of the coatings and bias applied to substrates have also been carried out. The microstructures and composition of TiN film were identified by the instrumental analyses such as scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The corrosion behavior of TiN coatings was studied in 0.5 M H2SO4 solutions by using potentiodynamic polarization method. The DC bias of −150 V was applied to the substrates to achieve a dense structure of approximately 400 nm coating of TiN, so that good corrosion protection of the Ti mesh and stainless steel substrates can be achieved. The TiN coating on stainless steel exhibited excellent corrosion behavior especially in lower corrosion current than 2×10−7 A/cm2.

Corrosion resistance of TiN coatings produced by various dry processes

The corrosion resistance of a TiN surface prepared by plasma-based ion implantation (PBII) was compared with that of TiN coating films prepared by sputtering deposition, plasma spraying, and shielded vacuum arc deposition. The corrosion test with the potentiodynamic polarization curve shows that the PBII sample had the best corrosion resistance. The SEM observation indicates that there was no pinhole on the TiN surface prepared by PBII. However, a lot of pinholes were observed in the TiN coating films prepared by the other dry coating processes.

Corrosion resistance of the vacuum arc deposited Ti, TiN and TiO2 coatings on large area glass substrates

An industrial installation for vacuum arc deposition is presented. Its potential in the field of decorative coatings for large area glass sheets is demonstrated. In particular it is possible to deposit patterned coatings through a polymeric textile mask. The ability to deposit uniform multilayer coatings having interference colours onto large silicate glass sheets is shown. Titanium, titanium nitride and titanium dioxide coatings on silicate glass have been characterized in terms of composition and corrosion resistance. Depth profiling was achieved with the aid of Auger electron spectroscopy. The corrosion resistance of TiN coatings is higher than that of TiO2. The corrosion resistance of vacuum arc deposited TiN coatings on glass was higher than that of TiN coatings produced by direct current reactive sputtering and plasma assisted chemical vapour deposition. Mask-deposited TiN coatings do not show any signs of accelerated corrosion along the border between the coated and uncoated glass.

Masked deposition of decorative coatings on large area glass and plastic sheets

An industrial installation for vacuum arc deposition is presented. Its potential in the field of decorative coatings for large area glass and plastic sheets is demonstrated, particularly its ability to deposit the patterned coatings with the aid of a textile polymeric mask. Titanium nitride, titanium dioxide and bilayer TiN/TiO2 coatings on silica glass have been characterized in terms of composition and corrosion resistance. The corrosion resistance of TiN coatings is higher than the corrosion resistance of TiO2. The corrosion resistance of vacuum arc deposited TiN coatings on glass prove to be higher than that of TiN coatings produced by DC reactive sputtering and plasma assisted chemical vapour deposition. Mask-deposited TiN coatings do not show any signs of accelerated corrosion along the border between coated and uncoated glass.