Effects of silicon powder content on the properties and interface bonding of nitrided Al2O3-C refractories

This study examines the various properties of high-quality fused corundum, corundum powder, and flake graphite with different contents of Si powder. The ceramic bonding phase can enhance the strength and modulus of ruptures in Al2O3-C refractories. The effects of Si powder content on the microstructure of nitrided Al2O3-C refractories are investigated. The results show that a large number of β-Sialon phases are formed in the nitriding process. This is the major ceramic bonding phase, generating columnar morphologies with smooth or conical tips when 6-14 wt% Si powder is added. When 10 wt% Si powder is added, the optimal bulk density, apparent porosity, cold crushing strength, and cold modulus of rupture are measured, and the optimal hot modulus of rupture is obtained from the formation of SiC whiskers in the test environment. The interface bonding of β-Sialon and corundum with different patterns can be observed in the Al2O3-C refractories.