Mechanical properties and adhesion of TiN thin films prepared by ion beam assisted deposition on ultrafine-grained WC-Co cemented carbide substrates

Abstract

This study unveils the effect of ion beam (IB) irradiation on mechanical properties and adhesion of titanium nitraide (TiN) thin films on ultrafine-grained WC-Co cemented carbide substrates. TiN thin films are used for improving wear resistance and lubricity of molds and cutting tools consisted of WC-Co cemented carbides. It is known that the ion beam assisted deposition (IBAD) improve the adhesion strength between the coatings and substrates. In this paper, TiN coatings were deposited on the ultrafine-grained WC-Co cemented carbide substrates by IBAD method that titanium was evaporated by an electron beam (EB) and nitrogen gas was introduced with/without IB. The chemical composition of TiN coatings deposited by IB were investigated by EPMA, XRD and XPS. The nitrogen ratio of TiN increased by IB irradiation in deposition process. The mechanical properties of TiN coatings with/without IB were evaluated by nanoindentation tests and ball-on-disc tests. Dynamic hardness and Young's modulus of TiN deposited by IBAD was 100% and 50% higher than that by conventional vapor deposition (VD), respectively. Friction coefficient of TiN deposited by IBAD was lower than that by VD. The adhesion of TiN coatings was measured by scratch tests. The adhesion strength of TiN deposited by IBAD was 21% higher than that by VD.

Keywords

• ion beam assisted deposition
• cemented carbide
• titanium nitride
• chemical composition
• adhesion