Wetting and interfacial behavior of molten Cu on Co–Si(–Mo) coated SiC

The wetting and spreading of molten Cu on SiC substrates with or without Co-Si(-Mo) coatings at 1120 degrees C were investigated by the sessile drop technique. The Co-Si(-Mo) coatings on the SiC substrate were prepared by liquid phase sintering process under a vacuum. The interfacial behaviors of the coating/substrate systems and the Cu/coated SiC wetting couples were analyzed. The experimental results indicated that the final contact angle of the Cu/SiC system at 1120 degrees C, for a holding time of 10 min, decreased from similar to 142 without coating to 12 degrees, 15-27 degrees and 7 degrees with the corresponding Co-Si, Co-Si-10Mo and Co Si-20Mo coatings. This result was closely related with the interactions between the Cu drop and the coatings. No reaction layer was observed at any of the coating/SiC interfaces before the wetting tests. However, a thin Mo-Co-Cu-Si layer and a graphitization layer with different thicknesses formed at the Cu/Co-Si-10Mo coated SiC and Cu/Co-Si-20Mo coated SiC interfaces. Moreover, the graphitization layer disappeared at the Cu/Co-Si-10Mo coated SiC interface when the thickness of the Co-Si-10Mo coating increased to similar to 60 mu m. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.