Effect of intermediate layer on wear-delamination life of low-frictional SiC-2.6mass%Ti film sputter-deposited on titanium substrate

In order to prevent an early wear delamination of the SiC-2.6%Ti film that has a very low friction coefficient of about 0.05, five types of intermediate layers (I-Ls) were sputter-deposited on a Ti substrate, and these specimens were then tested using a ball-on-disk type wear test machine. The sputter deposition of the I-Ls of Ti, SiO2, and Si(Ti)O2 increases the delamination life of the SiC-2.6%Ti top-film to a constant value when the I-L thickness is smaller than 0.4 μm, whereas that of the TiO2 I-L decreases the delamination life. For the SiC-3.6%Ti I-L, the delamination life of the top-film increases with increasing I-L thickness and it is longer than those for the Ti, SiO2 and Si(Ti)O2 I-Ls when the I-L thickness is more than 0.2 μm. The delamination occurs along the top-film/I-L interface for the Ti I-L, but along the I-L/substrate interface for the SiO2, Si(Ti)O2 and SiC-3.6%Ti I-Ls before the wear reaches the top-film/I-L interface. The increase in the delamination life by the existence of the I-L is due to the increase in the interfacial strength of both top-film/I-L and I-L/substrate boundaries. For the SiC-3.6%Ti I-L, the generation of residual compressive stress seems to be the main reason for the increase in the delamination life.