Chornobuk S. Synthesis and structural sensitiveness of mechanical properties of composite ceramics based on borides of transitional metals

The complex experimental analysis of phase- and structure formation of composite ceramic materials based on transitional metal borides, obtained with the method of reactionary hot-pressing is perfomed. The mechanism of co-operation between titan carbide and borone carbide within the temperature interval of 1100 – 1500 0C is found out. The methods of TiB2 – SіC – C composite materials synthesis is developed based on investigated pattern. Dependence of these composites mechanical properties from phase composition and features of their structure is also investigated. New Hf – HfB composite material, whith considerably higher values of microhardness then that of hafnium іs obtained and researched for the first time. A theoretical model of matrix biphase composite material fracture toughness is developed. Physical and mechanical properties of composite phases, concentration of defects in grains and in their boundaries, the ratio of matrix and including grain sizes and the difference of their thermal expansion coefficients are taken into account in the model.