Theoretical hardness analysis and experimental verification for composite ceramic tool materials

High hardness is the most important requirement for the property of cutting tool materials. Based on the assumption that the solid hardness is proportional to the resistance of the chemical bonds within indentation area, the theoretical hardness prediction model of the multiphase composite ceramic tool material was established combining with the hardness theory of multicomponent systems. In order to verify the applicability and accuracy of the theoretical model, validation experiment has been designed from the point of different dimensions and scales of raw materials, including TiC micron particles, SiC whiskers, TiC nanoparticles and SiC nanoparticles. The results showed that the experimental hardness of the materials with whiskers and micron particles addition were in good agreement with theoretical value with the error margin of −0.15 to +0.97%. By comparison, the experimental hardness of the material with nanoparticles addition was about +1.97–3.21% higher than theoretical counterpart. By analyzing experimental results and SEM micrographs, it was concluded that the experimental hardness of composite ceramic materials was scarcely influenced by the grain size of the matrix. And it was inferred that the intragranular and intergranular microstructure in nanocomposite ceramic materials might be the main factor that caused additional increment in experimental hardness.