Wear characteristics and performance of composite alumina-zirconia CVD coatings

Alumina-zirconia (Al2O3-ZrO2) composite CVD coatings have been developed for use in multilayered coatings on cemented carbide cutting tools. A composite coating containing 30-40% ZrO2 was machine tested as part of a WC-Co substrate/Ti(C, N)/Al2O3/Al2O3-ZrO2 coating configuration to analyze wear mechanisms. A range of composite compositions was also tested to measure performance. The composite coating is most effective in applications where failure mechanisms are driven by temperature and chemical diffusion. The composite coating reduces heat transfer to the substrate thus reducing deformation related cracking. It also reduces crystallite growth during CVD and provides a smoother coating than pure Al2O3.