Pulsed Bias Arc Ion Plating Research Articles

Deposition, structure and hardness of Ti–Cu–N hard films prepared by pulse biased arc ion plating

In this work, Ti–Cu–N hard nanocomposite films were deposited on 304 stainless steel (SS) substrate by using pulse biased arc ion plating system with Ti–Cu alloy target. The effects of negative substrate pulse bias voltages on chemical composition, structure, morphology and mechanical properties were investigated. The composition and structure of these films was found to be dependent on the pulse bias, whereas the pulse biases put little influence on hardness of these films. The XPS spectra of Cu 2p showed that obtained peak values correspond to pure metallic Cu. Cu content in Ti–Cu–N nanocomposite films changed with pulse bias voltage. In addition, X-ray diffraction analysis showed that a pronounced TiN (111) texture is observed under low pulse bias voltage while it changed to TiN (220) orientation under high pulse bias voltage. Surface roughness of the Ti–Cu–N nanocomposite films achieved to the minimum value of 0.11 μm with the negative pulse bias voltage of −600 V. The average grain size of TiN was less than 17 nm. The mechanical properties of Ti–Cu–N hard films investigated by nanoindentation revealed that the hardness was about 22–24 GPa and the hardness enhancement was not obtained.

Effects of pulsed bias duty ratio on microstructure and mechanical properties of TiN/TiAlN multilayer coatings

TiN/TiAlN multilayer coatings were deposited on M2 high speed steel by a pulsed bias arc ion plating system. The effect of pulsed bias duty ratio on the microstructure, mechanical and wear properties was investigated. The amount of macroparticles reduced with the increase of the duty ratio. The surface roughness was 0.0858 μm at duty ratio of 50%. TiN/TiAlN multilayer coatings were crystallized with orientations in the (1 1 1), (2 0 0) (2 2 2) and (3 1 1) crystallographic planes and the microstructure strengthened at (1 1 1) preferred orientation. At duty ratio of 20%, the hardness of TiN/TiAlN multilayer coatings reached a maximum of 3004 HV, which was 3.2 times that of the substrate. The adhesion strength reached a maximum of 77 N at 50% duty ratio. Friction and wear analyses were carried out by pin-on-disc tester at room temperature. Compared with the substrate, all the specimens coated with TiN/TiAlN multilayer coatings exhibited better tribological properties.

Performance of Ti–Ag-deposited titanium bipolar plates in simulated unitized regenerative fuel cell (URFC) environment

Titanium with excellent corrosion resistance, good mechanical strength and lightweight is an ideal BPP material for unitized regenerative fuel cell (URFC), but the easy-passivation property accordingly results in poor cell performance. Surface modification is needed to improve the interfacial conductivity. In this study, Ti–Ag film is prepared on TA1 titanium as bipolar plates for URFC by pulsed bias arc ion plating (PBAIP). Interfacial conductivity of Ti–Ag/Ti is improved obviously, presenting an interfacial contact resistance of 4.3 mΩ cm 2 under 1.4 MPa. The results tested by potentiodynamic, potentiostatic and stepwise potentiostatic measures in simulated URFC environments show that Ti–Ag/Ti has good anticorrosion performance, especially at high potential. The corrosion current density of Ti–Ag/Ti is approximately 10 −5.0 A cm −2, similar to that of uncoated titanium, at 2.00 V (vs. NHE) in a 0.5 M H 2SO 4 + 5 ppm F − solution at 70 °C with pressured air purging. Ti–Ag/Ti sample also has low surface energy. The contact angle of the sample with water is 102.7°, which is beneficial for water management in URFC. The bipolar plate with cost-effective Ti–Ag film combines the prominent interfacial conductivity with the excellent corrosion resistance at high potential, showing great potential of application in URFC.

Ti/TiN multilayer thin films deposited by pulse biased arc ion plating

In this work, the effect of modulation period (Λ) on Ti/TiN multilayer films deposited on high-speed-steel (HSS) substrates using pulse biased arc ion plating is reported. The crystallography structures and cross-sectional morphology of Ti/TiN multilayer films were characterized by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM), respectively. Their mechanical properties were determined via nanoindentation measurements, while the film/substrate adhesion via the scratch test. It was found that the highest hardness value reached 43GPa for the modulation period of 54nm, while the film/substrate adhesion also reached the highest value of 83N. Furthermore, the hardness enhancement mechanism in the multilayer films is discussed.

Chromium-containing carbon film on stainless steel as bipolar plates for proton exchange membrane fuel cells

A series of chromium-containing carbon films are deposited on 316L stainless steel (SS316L) as bipolar plates for proton exchange membrane fuel cells (PEMFCs) by pulsed bias arc ion plating (PBAIP). The film characterizations are evaluated by X-ray photoelectron spectroscopy (XPS) and X-ray diffractometry (XRD). Interfacial contact resistance (ICR) between the coated SS316L samples and carbon paper is measured. Potentiodynamic and potentiostatic tests in the simulated corrosive circumstance of PEMFC are conducted to evaluate the corrosion resistance of the coated SS316L samples. The results indicate the films are primarily composed of pure carbon atoms with amorphous structure, including sp 3 and sp 2 carbon atoms. The contents of sp 3 and sp 2 carbon atom are remarkably influenced by the doping chromium. ICR and corrosion resistance of the coated SS316L sample are greatly improved owing to the surface film. The lowest ICR between the coated SS316L sample and carbon paper is only 2.8 mΩ cm 2 at the compaction force of 120 N cm −2. The ICR has a close relationship with the contents of sp 3 and sp 2 carbon atom, and the lowest ICR is obtained for the Cr 0.23C 0.77 film with the lowest sp 3 carbon atom content and highest sp 2 carbon atom content. The SS316L sample with Cr 0.23C 0.77 film also exhibits the best corrosion resistance. Finally, the variations of ICR and surface morphology of the coated sample before and after corrosion testing are discussed.

Superhard C<SUB>1-x-y</SUB>N<SUB>x</SUB>Zr<SUB>y</SUB> Composite Films Prepared by Pulsed Bias Arc Ion Plating

用脉冲偏压电弧离子镀方法在保持石墨靶弧流恒定的条件下, 通过同步改变锆靶弧流与氮流量,在硬质合金基体上制备了一系列不同成分的C 1- x-y N x Zr y 复合薄膜. 随着锆靶弧流与N流量增加, 薄膜中Zr与N含量都呈线性增加, 同时C含量快速减少. Raman光谱显示所制备的薄膜具有DLC特征, 而XRD结果显示薄膜中还存在有明显的ZrN晶体相, 说明本实验所制备的薄膜属于在DLC非晶基体上匹配有ZrN晶体相的碳基复合薄膜. 随Zr与N含量增加，薄膜硬度先增大后降低, 当 x =0.19, y =0.28时薄膜具有最高硬度值, 为43.6GPa, 达到了超硬薄膜的硬度值.

V and N co-doped diamond-like carbon films deposited by pulsed bias arc ion plating

Abstract V and N co-doped diamond-like carbon (DLC–VN) composite films were deposited on cemented carbide substrates by pulsed bias arc ion plating. The effects of V and N contents on the structures and properties of the films were investigated by X-ray photoelectron spectroscopy (XPS), Raman spectra, grazing incident X-ray diffraction (GIXRD), transmission electron microscopy (TEM) and nano-indentation, respectively. The as-deposited films consist of a DLC–VN nanocomposite, where VN nanograins are embedded in an amorphous carbon matrix. The V and N contents have significant influences on the relative proportion of VN with respect to DLC. A proper concentration of VN nanocrystals in DLC induces even the formation of nano-diamond. The DLC–VN films have higher hardnesses than pure DLC films, which could be attributed to the nanocomposite structure.

Corrosion behavior of TiN-coated stainless steel as bipolar plate for proton exchange membrane fuel cell

Stainless steel is a potential material to be used as the bipolar plate for proton exchange membrane fuel cell (PEFC) because of its suitable physical and mechanical properties. Several coating techniques have been applied to improve its corrosion resistance. But seldom study is focused on the microstructure evolution with corrosion. In the present study, the use of TiN-coated stainless steel as the bipolar plate is evaluated. Two surface coating techniques, pulsed bias arc ion plating (PBAIP) and magnetron sputtering (MS), are adoped to prepare the TiN-coated stainless steel. Their corrosion resistances and electrical conductivities of the coated substrates are evaluated. The performance shows strong dependance on microstructural characteristics. The corrosion of SS304/Ti 2N/TiN prepared by MS mainly occurs on the grain boundary. The corrosion of SS304/TiN prepared by PBAIP mainly takes place from the large particles on the coating. The Ti 2N/TiN multilayer coating provides superb corrosion protective layer for stainless steel. Both the TiN and Ti 2N/TiN coatings provide low contact resistance.

Composition, microstructure and properties of C-N-V films prepared by pulsed bias arc ion plating

High quality C-N-V films with different compositions were prepared on cemented carbide substrate using pulsed bias arc ion plating. The surface morphology, composition, microstructure and properties of C-N-V films were investigated by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectra, grazing incident X-ray diffraction, and nano-indentation, respectively. The results show that the deposited films were nanocomposite films with VN nanocrystalline phase imbedded within diamond-like carbon(DLC) amorphous matrix. The hardness and elastic modulus, which are closely related to the composition and structure of the film, first increase and then decrease with increasing V and N contents and have the highest values of 368 and 5697 GPa exceeding that of pure DLC film prepared under the same condition when nitrogen content is 204% and vanadium content is 218%. The variation of V and N contents has significant influence on the phase structure, relative concentration of VN crystalline phase and DLC amorphous phase, and induces the formation of nano-diamond phase, hence has great effect on the properties of the films.

Influence of Nitrogen Flow Rate on the Microstructure and Properties of N and Me ( Me=Cr, Zr) Co-doped Diamond-like Carbon Films

In this paper, Me ( Me =Cr, Zr) and N co-doped diamond like carbon (DLC- Me N) composite films were prepared on cemented carbide substrates by pulsed bias arc ion plating. The effect of nitrogen flow rates on the microstructure and properties of the films were investigated by X-ray photoelectron spectroscopy (XPS), Raman spectra, grazing incident X-ray diffraction (GIXRD), high resolution transmission electron microscopy (HRTEM) and nano-indentation. Raman, GIXRD and HRTEM results show that the deposited films are nanocomposite films with Me N nanocrystalline phase embedded within DLC amorphous matrix, which are vital for the mechanical properties of the films. The nitrogen flow rate has significant effect on the compositions and structures and hence on the hardness and elastic modulus of the films, and increasing nitrogen flow rate decreases drastically the hardness and elastic modulus of the films.

Structure and properties of ZrN doped diamondlike carbon films prepared by pulsed bias arc ion plating

ZrN doped diamondlike carbon composite films with different compositions were deposited on cemented carbide substrates at different nitrogen flow rates by pulsed bias arc ion plating. Scanning electron microscopy results show that the film surfaces were all uniform, smooth, and dense. X-ray photoelectron spectroscopy reveal the C contents are more than 60%, the N content increases, and the Zr content decreases with increasing nitrogen flow rate. The Raman spectra indicated that the deposited films were diamondlike carbon. X-ray diffraction results suggested that a ZrN crystalline phase was also present in the films. The hardness and elastic modulus were closely related to the composition and structure of the films and decrease with increasing nitrogen flow rates, principally due to the increase in the sp2 content and the decrease in the ZrN crystalline phase.

Chromium nitride films on stainless steel as bipolar plate for proton exchange membrane fuel cell

Abstract A series of chromium nitride films are prepared on stainless steel substrates by pulsed bias arc ion plating (PBAIP) at different N 2 flow rate as bipolar plates for proton exchange membrane fuel cell (PEMFC). The film chemical composition and phase structure are characterized by X-ray photoelectron spectroscopy (XPS) and X-ray diffractometry (XRD). The characterization results indicate that the nitrogen content of deposited films varies from 0.28 to 0.50, and the phase structure changes from mixtures of Cr + Cr 2 N, pure Cr 2 N through Cr 2 N + CrN, to pure CrN. The interfacial contact resistance between samples and carbon paper is measured by Wang's method, and a minimum value of 5.8 mΩ cm 2 is obtained under 1.2 MPa compaction force. The anticorrosion property is examined by potentiodynamic test in the simulated corrosive circumstance of the PEMFC under 25 °C, and the lowest corrosive current density of 5.9 × 10 −7 A cm −2 is obtained at 0.6 V (vs. SCE). Stainless steel substrates coated by the film with lowest contact resistance are chosen as the bipolar plates to assemble cells. An average voltage value of 0.62 V is achieved at 500 mA cm −2 , which is close to that of the cell with Ag-plated bipolar plates.

TiN/TiC multilayer films deposited by pulse biased arc ion plating

TiN/TiC multilayer films were deposited on high-speed-steel (HSS) substrates using pulse biased arc ion plating. For comparison, TiN and TiC films were also deposited. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Auger electron spectroscopy (AES) were applied to investigate the modulation period thickness, microstructure and content depth distribution of the films, respectively. And microhardness and film/substrate adhesion were also analyzed using knoop tester and scratching method. The results showed that the multilayer films with different modulation period of 40–240 nm exhibit a modulation structure and the interface width is about 20∼30 nm. Microhardness of the multilayer films were not obviously improved compared to that of TiN and TiC film, and the reason was analyzed. In comparison to TiN film, film/substrate adhesion values of the multilayer films were deteriorated with the increasing of modulation period due to the brittle characteristics of TiC film.

Mechanical and optical properties of composite TiO xN y films prepared by pulsed bias arc ion plating

Composite TiO x N y films were synthesized with pulsed bias arc ion plating from two Ti target evaporators in a gaseous mixture of Ar, N 2 and O 2. With the substrate bias varying from 0 to −700 V, the structural, compositional, mechanical and optical properties of the films were characterized with X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), wear tests and UV–VIS absorption spectra. XRD and XPS results show that deposited at a substrate bias of −100 V, the film crystallized in a mixture of Anatase and Rutile TiO 2 phases with O locations partly substituted by N atoms. The threshold wavelength of optical absorption shifts from 367 to 400 nm after N doped, which is related with band gap narrowing cased by N doping. The wear tests indicate that friction efficient first decreases, then increases as the substrate bias goes up. The films deposited at a bias of −300 V exhibit the lowest friction efficient, less than 0.15. For the films on steel substrates, the TiO x N y films deposited at −300 and −500 V exhibit the highest adhesion strength and nano-hardness, respectively.

Carbon-based films coated 316L stainless steel as bipolar plate for proton exchange membrane fuel cells

Carbon-based films on 316L stainless steel were prepared as bipolar plates for proton exchange membrane fuel cells (PEMFCs) by pulsed bias arc ion plating. Three kinds of films were formed including the pure C film, the C–Cr composite film and the C–Cr–N composite film. Interfacial conductivity of the bipolar plate with C–Cr film was the highest, which showed great potential of application. Corrosion tests in simulated PEMFC environments revealed that the C–Cr film coated sample always showed better anticorrosive performance than 316L stainless steel either in reducing or oxidizing environments. The C–Cr film coated bipolar plate sample also had high surface energy. The contact angle of the C–Cr film coated sample with water was 92°, which is beneficial for water management in a fuel cell.

Optimized Cr-nitride film on 316L stainless steel as proton exchange membrane fuel cell bipolar plate

Pulsed bias arc ion plating was used to form Cr-nitride films on stainless steel as bipolar plate of proton exchange membrane fuel cell. Surface micrograph, film thickness, film composition, corrosion resistance, interfacial conductivity and contact angle with water of the sample obtained at the optimal flow rate of N 2 were investigated. The atomic ratio of Cr to N was close to 2:1 and the CrN phase with crystal planes of (111), (200), (220) and (311) was found in the film. Potentiodynamic and potentiostatic tests showed that the corrosion resistance of the bipolar plate sample was greatly enhanced. The contact resistance between the bipolar plate sample and Toray carbon paper was about two orders of magnitude lower than that of 316L stainless steel. The contact angle of the sample with water was 95°, which is beneficial for water management in fuel cells.

High-temperature oxidation resistant (Cr, Al)N films synthesized using pulsed bias arc ion plating

(Cr, Al)N films were deposited by pulsed bias arc ion plating on HSS and 316L stainless steel substrates. With pulsed substrate bias ranging from −100 V to −500 V, the effect of pulsed bias on film composition, phase structure, deposition rate and mechanical properties was investigated by EDX, XRD, SEM, nanoindentation and scratch measurements. The high-temperature (up to 900 °C) oxidation resistance of the films was also evaluated. The results show that Al contents and deposition rates decrease with increasing pulsed bias and the ratio of (Cr + Al)/N is almost constant at 0.95. The as-deposited (Cr, Al)N films crystallize in the pseudo-binary (Cr, Al)N and Al phases. The film hardness increases with increasing bias and reaches the maximum 21.5 GPa at −500 V. The films deposited at −500 V exhibit a high adhesion force, about 70 N, and more interestingly good oxidation resistance when annealed in air at 900 °C for 10 h.

Investigation on CNx films deposited by pulsed bias arc ion plating

The CNx films with different nitrogen contents were prepared on single crystal Si(100) substrate under different nitrogen flow rates by pulsed bias arc ion plating. The surface morphology,composition,structure and properties of CNx films are investigated by optical microscope (OM),X-ray photoelectron spectroscopy(XPS), X-ray diffraction(XRD),Raman spectra and Nano-indentation, respectively. The results show that the surface of the films is uniform,smooth and dense. The nitrogen content in the CNx films decreases with the nitrogen flow rate decreasing. The results indicate that the deposited films are amorphous and have the typical characteristic of diamond-like carbon films. As the nitrogen content decreases from 18.9% to 5.3%, the hardness and elastic modulus of the films increase monotonically to a large extent, of which the hardness increases twice from 15.0 to 30.0 GPa. The sp3 content in the CNx films can be sensitively adjusted by controlling the nitrogen flow rate, leading to the changes of hardness and elastic modulus in large ranges.

Coated 316L stainless steel with Cr xN film as bipolar plate for PEMFC prepared by pulsed bias arc ion plating

Three different kinds of Cr x N films on 316L stainless steels were prepared by pulsed bias arc ion plating as bipolar plates for proton exchange membrane fuel cell (PEMFC). The interfacial contact resistance, corrosion resistance and surface energy of the bipolar plate samples were investigated. Among the three samples, the 316L stainless steel coated with Cr 0.49N 0.51 → Cr 0.43N 0.57 gradient film (sample 2) exhibited the best-integrated performance. The contact resistance between sample 2 and Toray carbon paper was 6.9–10.0 mΩ cm 2 under 0.8–1.2 MPa. The bipolar plate sample also showed improved corrosion resistance in simulated PEMFC environments. Either in the reduction environment or in the oxidation environment 25 °C and 70 °C, the corrosion current densities of sample 2 were about one to two orders of magnitude lower than those of the base metal. In addition, the open circuit corrosion potential of sample 2 was also the highest in 0.5 M H 2SO 4 + 5 ppm F − solution at 25 °C. The treated bipolar plate had high surface energy; and the contact angle of sample 2 with water was about 90°, which is beneficial for water management in fuel cell.

Structural and Mechanical Properties of AlN Films by Pulsed Bias Arc Ion Plating

AlN thin films have been deposited on p-(100) Si and glass substrates by pulsed bias arc ion plating at different negative substrate biases. The crystal orientation, deposition rate and mechanical property of the films were investigated by X-ray diffraction, nanoindenter and UV-VIS spectrophotometer. The results reveal that pulsed bias has a large influence on film preferred orientation, deposition rate and mechanical property. A preferred (110) orientation is observed in the film deposited at a bias of -50V. With the increase of the bias, film deposition rate decreases first sharply then wildly; Film hardness and elastic modulus first increase, then decrease and finally increases. Higher value of film harness obtained at the bias of -50V and -500V relates to the (110) preferred orientation and grain refinement respectively.