Metallothermic SHS of Al2O3–Cr2O3 + TiC ceramic composite material

Abstract

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 α of CrO3 + Al in the general charge was found to raise the synthesis temperature. For α < 0.2, sintered multiphase products were formed. In case of high additive content (α > 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°С was found to possess density of 4.55 g/cm3, hardness of 20 GPa, flexural strength of 680 MPa, and crack resistance of 4.2 MPa m1/2.