Papers by Keyword: Chromium Nitride

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Authors: A.M. Peters, John J. Moore, Ivar Reimanis, Brajendra Mishra, Roland Weiss
Authors: Chang Yong Choi, Dae Geun Nam
Abstract: Bipolar plate of stack in polymer electrolyte membrane fuel cell (PEMFC) has high cost and heavy weight. In this study, low carbon steel was used as a base metal of bipolar plate for the lower cost than stainless steels, which are widely researched as bipolar plate. Low carbon steel has not a good corrosion resistance. In order to improve the corrosion resistance and electrolytic conductivity, low carbon Steel needs to be surface modified. We made chromium electroplated layer of 5㎛ and 10㎛ thickness on the surface of low carbon steel, and it was thermally nitrided for 3hours at 1173K in a furnace with 50torr nitrogen gas pressure. Cross-section and surface microstructures of surface treated low carbon steel were investigated using OM and SEM. Also crystal structures are observed by XRD. Interfacial contact resistance and corrosion test were considered to simulate the internal operating conditions of PEMFC stack. The corrosion test was performed in 0.1N H2SO4 + 2ppm F- solution at 80°C. The results show that the surface modified steel plates have good corrosion resistance and relatively low interfacial contact resistance, and it should be candidate material as a bipolar plate of PEMFC.
Authors: Jamie Pennington, Bradley P. Wynne, Glenn Byrne
Abstract: A constitutive equation of flow stress based on the Norton-Hoff equation has been developed for the high chromium and nitrogen containing super duplex stainless steel, ZERON® 100 (UNS S32760). This was then used to model, using the finite element method, the strain distribution within a uniaxial compression test under typical two-phase forging conditions. Predictions from the model were used to correlate deformation history to microstructure morphology. The microstructure consisted of austenite, γ islands (both primary and secondary) within a ferrite, δ matrix that contained chromium nitride precipitates. For deformation temperatures of 1050°C and 1120°C, the small secondary austenite was equiaxed, whilst at 1280°C the secondary austenite exhibited a Widmanstätten morphology. The highest level of nitride precipitation occurred at the highest deformation temperatures, i.e. highest volume fraction of ferrite, independent of strain rate. This suggests that nitride precipitation appears to be driven to a greater extent by thermal factors than deformation substructure.
Authors: Ming Der Jean, Wesley Huang, Jium Fang
Abstract: This paper presents the optimal chromium nitride (CrN) deposited performance by tuning magnetic systems on die steel in PVD. The strength of magnetic fields was controlled by adjusting the gap distance between magnet sets and target surfaces of the unbalanced magnetic field of sputtering systems. In L18 orthogonal experiments, the effect of control factors were explored such as gap distance between magnet set and target surface (GDMT), target current, argon and nitrogen flow rate, DC pulse frequency, and work distance. Hardness and wear behavior of the CrN films were analyzed using a statistical method. The wear rate was estimated by Pappus’s theorem. Among the results, the Cr2N phase with the mixture crystallographic orientations of (111) and (002) exhibited better wear resistance than CrN(200) with a single preferential orientation. In addition, variance analysis exhibited the largest percentage contribution to friction coefficient in comparison with the other two properties of friction coefficient and GDMT, which showed that GDMT is extremely sensitive to friction coefficient.
Authors: Kyoung Chul Shin, Jong Min Lim, Chong Mu Lee
Abstract: The hexavalent chromium used in chromium plating is so toxic that it is very hazardous to human body and even carcinogenic. Therefore, it is indispensable to develop an alternative deposition technique. To explore the feasibility of sputtering as an alternative technique for chromium plating, we investigated the dependences of the deposition rate, the phases, the hardness, the surface roughness and the corrosion-resistance of CrNx deposited on the high speed steel substrate by using a dual ion beam sputtering system on the rf-powers. The deposition rate of CrNx depends more strongly upon the rf-power for argon ion beam than that of the nitrogen ion beam. The hardness of the CrNx film can be maximized by optimizing the rf-power, so that the volume percent of the Cr2N phase in the film is highest. Amorphous films are obtained when the rf-power for nitrogen ion beam is much higher than that for argon ion beam. The CrNx film deposited by using the sputtering technique under the optimal condition provides corrosion-resistance comparable to that of the electroplated chromium.
Authors: Gui Hua Li, Yong Zou, Zeng Da Zou, Xiao Nan Li
Abstract: In this paper, the Fe-based cladding layer was prepared on 42CrMo substrate by laser cladding mixture containing chromium nitride. The effects of chromium nitride on microstructure and property of cladding layer were studied. The experimental results indicate the chromium nitride is unstable during the process of laser cladding. It is very difficult to obtain chromium nitride in the laser cladding layer. However, the addition of chromium nitride in cladding powders could promote the formation of austenite phase, and increase the microhardness of cladding layer. The reason about increasing the microhardness of cladding layer is the formation of little carbide and solution strengthening of nitrogen, not the strengthening from chromium nitride.
Authors: Takuya Ide, Takehiro Wada, Hideo Nakajima
Abstract: Lotus-type porous iron was fabricated by continuous zone melting technique through thermal decomposition of chromium nitride(Cr1.18N). Nitrogen dissolves into the molten iron through thermal decomposition of Cr1.18N. When the molten iron is solidified in one direction, insoluble nitrogen forms the directional gas pores aligned along the solidification direction. The porosity increases with increasing transfer velocity. For most of lotus metals fabricated by pressurized gas method, the porosity does not change with the transfer velocity owing to constant gas solubility in liquid and solid phase. On the other hand, the porosity of lotus metal fabricated by thermal decomposition method depends on the transfer velocity. This difference is attributed to the decomposition behavior of gas compound dependent upon the heating rate.
Authors: Q.G. Zhou, Xin De Bai, Yun Han Ling, Xiao Wei Chen, D.Q. Peng
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