CVD Coating of Oxide Particles for the Production of Novel Particle-Reinforced Iron-Based Metal Matrix Composites

Abstract

This paper focuses on surface metallization of oxide particles by means of titanium nitride (TiN) thin films for the production of highly wear-resistant metal matrix composites (MMC) on Fe-base for wear protection applications. These powder-metallurgically produced materials consist of a metallic matrix with embedded oxide hard-particles such as alumina or zirconia. The poor wettability of these oxides by iron-base melts and the resulting weak bonding between the components lead to porous materials and weak tribomechanical properties, thus limiting the material’s application range. To counteract such problems, this paper describes a processing route in which the oxide particles are pre-metallized by application of a thin TiN coating by means of chemical vapor deposition (CVD). This surface metallization should increase the wettability and bonding behavior between the ionically bonded particles and the iron-base alloy, which should improve the mechanical and tribological properties. Therefore, a CVD device for coating ceramic particles was constructed and is described in this paper. Furthermore, coatings deposited on the ceramic substrates were investigated by means of RBS, SEM and XRD. In addition, the feasibility of producing metal matrix composites (MMC) by admixing the TiN-coated oxide particles with a Fe-base alloy and their further densification by supersolidus liquid-phase sintering is demonstrated.