Adhesion improvement of the diamond film in diamond-coated WC-Co insert prepared with AC substrate bias

Abstract

The grain size of diamond film deposited on WC-Co insert can be reduced by AC substrate bias during deposition, which enables a smooth surface finish of a workpiece during machining process. However, the adhesion of diamond film deposited on WC-Co insert became poor due to AC bias application, which was attributed to the increased surface Co content. To maintain adhesion strength while achieving,grain size refinement by AC-biased growth, a certain thickness of diamond layer grown without bias was introduced as a buffer layer. The AC bias was applied after diamond deposition of 8 and 15 mu m in thickness without bias and the total thickness of the diamond film was controlled to be around 20 mu m. The adhesion strength of diamond film for the diamond-coated WC-Co insert prepared with AC bias, measured by indentation technique, was greatly improved by the adoption of diamond buffer layer deposited without bias. (c) 2004 Elsevier B.V. All rights reserved.