Abstract
Scratch test has been done for chemically vapor deposited (CVD) TiC and physically vapor deposited (PVD) TiN on WC-Co alloy substrates using the pyramidal indentator. The acoustic emission has been observed accompanied by cracking in the film and detaching of the film from the substrates at the interface. The AE singnals increased abruptly at the critical load at which the detachment began to occur and were constant after critical loading. The critical load corresponds to the detaching of the film from the substrates at the interface. The detached width after scratching also increased with load and was apart from the diagonal of the indentator from the critical load. The scratching depth at the critical load was 1/2-3/5 of the film thickness, which means the indentor did not reach the interface. These results were understood from the introduction of lateral cracks at the unloading by passing through the indentator.
