An internal synthesis method for producing a mullite–chromium carbide composite

Abstract

In situ formation of chromium carbide in mullite matrix through the reaction of Cr2O3, SiC, and Al2O3 has been studied. Three different chromium compounds, Cr3Si, Cr3C2, Cr7C3, and mullite were formed. The Cr3Si particles formed first and the Cr7C3 phase was only dominant above 1600 °C. The Cr3C2 phase was the main product chromium carbide at temperatures ranging from 1450–1550 °C. The mullite phase formed concurrently through the reaction of SiO2 with Al2O3. SiO2 is the product of the reaction between Cr2O3 and SiC. The composite hot-pressed at 1450 °C in argon gives a flexural strength and fracture toughness up to 407 MPa and 3.8 MPa m1/2, respectively.