The surface segregation of substrate elements through the Au layer in the Au-Ni-Kovar sys-tem specimens heated at 250—350℃ for 0.5—1.5 h has been studied by SAM and XPS.Visual evidence of the mechanism for Ni and Co surface segregation of the complicated sys-tem has been given,i.e.Ni and Co penetrated the gold layer mainly by grain boundary diffu-sion and then covered the Au layer by surface diffusion.The strdy results of the chemicalstates of surface segregation elements not only indicate that oxygen adsorption and oxidationreaction are the driving force for the surface segregation of Ni and Co,but also show that theabove segregation can result in water absorption on surfaces.
展开▼
