Nitridation of chromium powder in ammonia atmosphere  

作　　者：Ling Li Qiang Zhen Rong Li 

机构地区：[1]Nano-Science and Technology Research Center, Shanghai University [2]School of Materials Science and Engineering, Shanghai University

出　　处：《International Journal of Minerals,Metallurgy and Materials》2015年第3期319-324,共6页矿物冶金与材料学报（英文版）

基　　金：financially supported by the Innovation Foundation of Shanghai University (Nos. sdcx2012033 and sdcx2012062);the Special Research Foundation for Training and Selecting Outstanding Young Teachers of Universities in Shanghai (No. B.37-0407-12-008);the National Natural Science Foundation of China (Nos. 51072112 and 51272154);the Projects of International Cooperation and Exchanges NSFC (No. 51311130110)

摘　　要：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）.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 

分 类 号：TB383.3[一般工业技术—材料科学与工程]