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韦春贝,林松盛,代明江,石倩,苏一凡,唐鹏.固体渗铬层组织结构及性能稳定性研究[J].稀有金属材料与工程(英文),2021,50(5):1706~1712.[Chunbei Wei,Songsheng Lin,Mingjiang Dai,Qian Shi,Yifan Su and Peng Tang.Structure and performance stability of chromized coating by pack cementation[J].Rare Metal Materials and Engineering,2021,50(5):1706~1712.]
Structure and performance stability of chromized coating by pack cementation
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Received:April 13, 2020  
DOI:
Key words: pack-cementation chromizing  natural ageing  phase structure  hardness  adhesion strength
Foundation item:广东特支计划资助(2019BT02C629);广东省科学院创新能力建设项目(2018GDASCX-0111);广东省重点领域研发计划(2020B010184001)
Author NameAffiliation
Chunbei Wei,Songsheng Lin,Mingjiang Dai,Qian Shi,Yifan Su and Peng Tang  
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Abstract:
      Chromized coatings were fabricated using a conventional pack-cementation method. Effect of chromizing time, as well as natural ageing on the structure and performance was investigated. The phases and microstructure were characterized by scanning electron microscopy (SEM) with EDS and X-ray diffraction (XRD). The microhardness of the surface, the nanohardness of cross-section, the adhesion strength of the coatings were characterized by Vickers microhardness tester, nano-indenter and Rockwell-C tester. The results show that the chromized coatings were composed of Cr2N, (Cr,Fe)23C6 and (Cr,Fe)7C3. In the top surface, the discontinous Cr2N crystal grains distributed in the loose chromium carbides. The Cr2N crystal grains growth larger as the chromizing time increased. In the sublayer, the phase was composed of chromium carbides. The gradient structure was formed in the chromized coatings with Cr content decreased from surface to substrate and the contrary trend for Fe content. The microhardness of the surface was between 1492HV0.05~1698HV0.05 and it decreased slightly after 1 year natural ageing. The nanohardness reduced with Cr content decreasing in cross-section of chromized coatings. The Rockwell-C test results show that there were some radial cracks and spalls around the indentation crater. However, only radial cracks were presented around the indentation craters after 1 year natural ageing, indicated the improvement of adhesion strength of the coatings to substrate.