Wettability of Graphite/Ni plus Cr System
Carbon fiber reinforced CMCs (ceramic matrix composites) are promising high temperature structural materials for aeronautical and astronautical industries. But the engineering application of the materials strongly depends on the joining technique. As a fundamental research, high strength graphite can be used to simulate carbon fiber. The study of wettability of graphite by liquid metals contributes to the development of joining technique of carbon fiber reinforced CMCs. The wettability of graphite/Ni plus Cr system was investigated using the sessile drop method. The contact angle was determined by high temperature photography. The microstructure and composition of the interfacial zone were analyzed by SEM, EDX and XRD. The contact angle of graphite/Ni plus Cr system decreases with increasing the Cr content. It becomes zero, when the Cr content reaches 50wt%. The wetting of graphite/Ni plus Cr system is chemical wetting. The contact angle of the system decreases with increasing the wetting temperature or prolonging the holding time. The higher the Cr content, the more remarkable the effects of the temperature and the holding time on the contact angle are. Microstructure and phase analysis reveals that inter-diffusions and interfacial reactions take place in the wetting process. The reaction products include Cr3C2. The formation of Cr3C2 contributes to the interfacial bonding and results in the accumulation of Cr in the interfacial zone.
Wei Pan and Jianghong Gong
S. J. Li et al., "Wettability of Graphite/Ni plus Cr System", Key Engineering Materials, Vols. 368-372, pp. 1621-1624, 2008