Hybrid Alumina Composites for Cutting Tool Inserts: Material Design and Development

A successful approach to the development of reinforced materials for enhanced cutting tool inserts requires the formulation and application of innovative concepts at each step of material design development. In this paper, reinforced ceramic-based cutting tools with enhanced thermal and structural properties are developed for high-speed machining applications using a computational approach. A mean-field homogenization, effective medium approximation and J-integral based fracture toughness evaluation using an in-house code are used for predicting the effective structural and thermal properties for tool inserts as a function of reinforcement type, volume fraction, particle size and interface between matrix and reinforcement. Initially, several potential reinforcements are selected at the material design phase. SiC, TiB2, cBN and TiC were all found to be suitable candidates when reinforced into an alumina matrix as both single and hybrid inclusions for the enhancement of thermal and structural properties. For validation purposes, alumina-cubic boron nitride-silicon carbide composites are developed using Spark Plasma Sintering as hybrid systems, which are in line with the designed range of volume fraction and reinforcement particle size. Structural and thermal properties such as elastic modulus, fracture toughness and thermal conductivity are measured to complement the computational material design model.