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Nitridation of chromium powder in ammonia atmosphere

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International Journal of Minerals,Metallurgy and Materials 2015年第3期22卷 319-324页

作者： Ling Li Qiang Zhen Rong Li Nano-Science and Technology Research Center Shanghai University School of Materials Science and Engineering Shanghai University

CrN powder was synthesized by nitriding Cr metal in ammonia gas flow, and its chemical reaction mechanism and nitridation process were studied. Through thermodynamic calculations, the Cr-N-O predominance diagrams were constructed for different tempera- tures. chromium nitride formed at 700-1200℃ under relatively higher nitrogen and lower oxygen partial pressures. Phases in the products were then investigated using X-ray diffraction （XRD）, and the Cr2N content varied with reaction temperature and holding time. The results indicate that the Cr metal powder nitridation process can be explained by a diffusion model. Further, Cr2N formed as an intermediate product because of an incomplete reaction, which was observed by high-resolution transmission electron microscopy （HRTEM）. After nitriding at 1000℃ for 20 h, CrN powder with an average grain size of 63 nm was obtained, and the obtained sample was analyzed by using a scanning electron microscope （SEM）.

关键词： chromium powder nitridation chromium nitride ammonia chemical synthesis reaction mechanism

Nano Cr Interlayered CrN Coatings on Steels

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Tsinghua Science and Technology 2005年第6期10卷 690-698页

作者： Pranav Deshpande Department of Chemical and Materials Engineering M.L. #12 University of Cincinnati Cincinnati OH 45242 USA

CrN coated steels assisted with a nano Cr interlayer were investigated. The Cr nano-interlayers were prepared by sputter deposition with a thickness about 70-100 nm. CrN coatings were also prepared by sputter deposition on the Cr nano-interlayers. The crystal structures, microhardness, and scratch resistance of CrN/Cr coatings were determined. Results show that the Cr nano-interlayers improve scratch resistance and the microhardness of CrN coated steels. A rapid heat treatment with infrared （IR） was performed for coated specimens in the attempt to improve bonding, With IR heat treatments, the beneficial effect of the Cr nano-interlayers was clearly observed. Without the Cr nano-interlayers, severe cracks on the surface of coatings were observed after IR heat treatment. However, with a Cr interlayer, no cracks on the surface of CrN coatings were observed after the heat treatment. The scratch resistance of coatings was also affected by the Cr nano-interlayers. The scratch track was clean and showed significantly smaller amount of scratch debris for CrN coatings with Cr interlayers than those without the Cr nano-interlayers. The microhardness of coatings with the Cr nano-interlayers is higher than those without the Cr nano-interlayers after IR heat treatment. The Cr and CrN phase have been identified with X-ray diffraction analysis, and the results show that the higher the nitrogen content in the sputtering gas, the stronger the CrN peaks observed in the diffraction patterns are.

关键词： hard chromium replacement chromium nitride chromium nano-interlayer reactive sputter deposition infrared heat treatment

Structure and properties of CrN coatings formed using cathodic arc evaporation in stationary system

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Transactions of Nonferrous Metals Society of China 2019年第4期29卷 799-810页

作者： B.WARCHOLINSKI A.GILEWICZ A.S.KUPRIN I.V.KOLODIY Faculty of Technology and Education Koszalin University of Technology National Science Center Kharkov Institute of Physics and Technology

CrN coatings were deposited using cathodic arc evaporation in stationary system on the substrate surface faced to the plasma source and on the back *** effect of nitrogen pressure on the structure and phase composition,mechanical and tribological properties of the coatings was *** coating morphology and structure were characterized using SEM and contact profilometry and X-ray diffractometry,*** properties were studied by *** friction and wear properties of the coatings were investigated by ball-on-disk *** increase in nitrogen pressure during coating deposition results in phase transformation according to the relation Cr2N→Cr2N+CrN→*** roughness of the coatings deposited on the front side of the substrate is higher than that on the back side,mainly due to larger number of *** hardness and elastic modulus are also higher on the front side of the *** adhesion and wear rate of the coatings have an inverse relationship.

关键词： chromium nitride arc evaporation phase composition roughness hardness wear