Evaluation of titanium carbide thin film coatings on WC-Co following surface microstructure treatments

摘要

The effects of acid or radio-frequency (RF) CF4 plasma pre-treatments before a sputtered titanium carbide (TiC) hard coating thin film were investigated to increase the adhesion strength of TiC on WC-16wt%Co substrate. The arithmetic average roughness (Ra) was 182.5nm after a 5-min aqua regia treatment at 60 degrees C and 247.8nm after 30min of RF CF4 plasma at a substrate temperature of 500 degrees C. Chemically bonded cobalt disappeared from the WC-Co substrate surface on treatment with aqua regia for 5min based on X-ray photoelectron spectroscopy (XPS). The TiC thin film on substrate with Ra=150.3nm after CF4 plasma treatment at 300 degrees C for 30min did not delaminate at up to 30N, in contrast, the substrate with Ra=182.5nm after aqua regia treatment at 60 degrees C for 5min underwent delamination at below 30N. The adhesion strength was maximal, with a surface roughness of Ra approximate to 150nm, with CF4 and aqua regia treatments.