CVD diamond coating on WC cutting tool using electrophoresis

CVD diamond films were deposited on commercial WC cutting tools. An electro n cyclotron resonance microwave plasma chemical vapor deposition (ECR-MPCVD ) apparatus was used to deposit diamond films. Methane and hydrogen were us ed as gaseous source for CVD, and WC-Co (JIS standard: K-10) was used as a substrate for CVD. Cobalt on the surface of the WC cutting tool prevented C VD diamond from depositing on the WC cutting tool. Scratching with diamond particles on the surface of the WC cutting tool, which is one of the most p opular pretreatments for enhancing the nuclei density of CVD diamond, was i neffective on the WC cutting tool without removing surface cobalt. On the o ther hand, Electrophoresis treatment was effective for increasing diamond n uclei density on the WC cutting tool without removing surface cobalt. Howev er, CVD diamond films synthesized on the WC cutting tool (from which surfac e cobalt was removed) using electrophoresis pretreatment separated from the surface of the WC cutting tool. To improve the adhesion between CVD diamon d film and WC cutting tool, heat treatment was performed after electrophore sis pretreatment. The heat treatment condition was 500 degreesC for I h in Ar flow. The heat treatment after electrophoresis treatment was effective f or improving adhesion between WC surface and CVD diamond film. Vickers hard ness test was carried out for estimating the adhesion. The Vickers hardness of the CVD diamond film obtained by the electrophore sis -heat pretreatmen t, was as hard as that of a CVD diamond film obtained with conventional scr atching pretreatment. From the results of Vickers hardness test, it was fou nd that heat treatment after electrophoresis process is effective for impro ving the strength of the adhesion layer.