Metallothermic SHS of Al2O3-Cr2O3 + TiC ceramic composite material

Ceramic composite material Al2O3-Cr2O3 + TiC was prepared by metallothermic self-propagating high-temperature synthesis (SHS) under 5 MPa of Ar pressure from green mixtures containing TiO2, Al, and C powders, and additive of CrO3 + Al blend. An increase in the mass fraction alpha of CrO3 + Al in the general charge was found to raise the synthesis temperature. For alpha < 0.2, sintered multiphase products were formed. In case of high additive content (alpha > 0.2), the combustion products were separated into two layers: carbide and oxide phases. Optimum synthesis conditions for forming the cast product consisting of Al2O3-Cr2O3 solid solution ("ruby") and uniformly distributed TiC particles were found. In order to evaluate the possibility of using this material as a cutting tool, physical and mechanical properties were determined. SHS-prepared Al2O3-Cr2O3 + TiC composite after 24-h milling in a planetary mill, pressing under a pressure of 200 MPa, and sintering at 1460 degrees C. was found to possess density of 4.55 g/cm(3), hardness of 20 GPa, flexural strength of 680 MPa, and crack resistance of 4.2 MPa m(1/2).