Liquid phase sintering-based coating of Al2O3/TiC composite layer on cemented carbide

•The Al2O3 and TiC coatings are achieved simultanelously with non vapor method.•The coating process is combined with the sintering of cemented carbide substrate.•TiO2 sol transforms to TiC by carbonthermal reducation reaction during sintering.•Carbon-deficit condition on the surface results in a rounded shape of WC.•Ti results in the micro multi-stepped microstructure of WC by 3D growth mechanism.

A novel technology is introduced to facilitate the preparation of Al2O3/TiC composite layer on cemented carbide, which is based on liquid phase sintering process other than chemical/physical vapor deposition method. Al2O3/TiO2 sol is dip-coated on cemented carbide green compact, which transforms to crystal Al2O3/TiC by carbothermal reduction reaction during sintering. The surface layer is composed of WC, Co and Al2O3/TiC phases. The reaction creates carbon-deficit condition on the surface and results in the disappearance of Co capping and round-edged WC grains. The WC has micro and multi-stepped microstructure, indicating a 3D growth mechanism. The introduction of Al2O3/TiC is responsible for the layer-by-layer structure other than equilibrium faceted (truncated) triangle prism shape of WC.