Abstract
Refractory castables were prepared from 85 mass% graded SiC slab waste as an aggregate and 15 mass% of either 50% or 80% alumina cement using the suitable amount of gauging water. The prepared castable samples were subjected to different firing temperatures 20 degrees C, 800 degrees C, 1000 degrees C, 1300 degrees C, 1400 degrees C, 1500 degrees C and 1600 degrees C. The sintering parameters (bulk density and apparent porosiy), mechanical properties (cold crushing strength) as well as refractory properties (refractoriness, thermal shock resistance as well as refractoriness under load) were tested according to the international standard specifications. The mineralogical compositions of the fired castables were investigated using X-ray diffraction analysis (XRD). The microstructure of some selected fired castable samples was testes using scanning electron microscope (SEM) attached with energy dispersive X-ray unit (EDX). Castable samples containing 50% alumina cement showed good sintering, mechanical as well as refractory properties limited up to 1400 degrees C while those of castable samples containing 80% alumina cement are extended to 1600 degrees C. The improved properties of the fired castables are correlated with the matrix advantage system; mullite-SiC-CA(6)-corundum resulting from the reaction of the fine grains of SiC with calcium aluminate cement. The relatively improved properties of castables containing 80% alumina cement is due to the high purity of the cement and hence the little content of the low melting phases formed which affect adversely the refractory properties of castable samples containing 50% alumina cement. SiC refractory castables bonded by CAC can be nominated as refractory lining for the ancillary areas (coolers, nozzles, burner, and cone) and preheaters of the rotary cement kiln. (C) 2010 The Ceramic Society of Japan. All rights reserved.