Chromium carbide coatings produced on ductile cast iron QT600-3 by thermal reactive diffusion in fluoride salt bath: Growth behavior, microstructure evolution and kinetics. Issue 1 (January 2019)

• Record Type: Journal Article
• Authors: Su, Xingzhi; Zhao, Sufang; Sun, Hua; Yang, Xingmei; Zhang, Peng; Xie, Leidong
• Is Part Of: Ceramics international. Volume 45:Issue 1(2019)
• Page Start: 1196
• Page End: 1201
• Publication Date: 2019-01
• Subjects: Growth behavior -- Microstructure evolution -- Chromium carbide coating -- Thermal reactive diffusion; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2018.09.304
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: A series of chromium carbide coatings were formed on ductile cast iron QT600-3 by thermal reactive diffusion (TRD) processes in fluoride salt bath at 850–980 °C for 10 min ~ 40 h under an argon atmosphere. Coatings were analyzed by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDX). The results demonstrate that the microstructure of chromium carbide coatings formed on ductile cast iron QT600-3 at 850 °C is related to the treatment time. At first 10 min, there is only a thin layer of Cr7 C3 in the coating. At 1 h, the outermost layer of the coating is a thin Cr23 C6 layer, and there is a thin M3 C layer beneath the M7 C3 layer. With increasing treatment time, the thickness of all layers in the coatings increases. For the sample treated for longer than 1 h, the microstructure of coating is Cr23 C6, M7 C3 and M3 C from the outermost layer to the substrate. The microstructure of chromium carbide coatings formed on high C content steel substrates via TRD processes is independent with the composition of the base salt. The growth kinetics of chromium carbide coating follows a parabolic law with an activation energy of 129.906 kJ/mol. The evolution of hardness of coatings is consistent with the microstructure evolution of coatings.