UTILIZATION OFKAOLIN (KANKARA CLAY) AND GREY CAST IRON FOR THE PRODUCTION OF COMPOSITE REFRACTORY

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Department of Environmental Design

ABSTRACT
In this study, Kaolin (Kankaraclay) was used as a matrix material which was reinforced with Grey cast iron (GCI) to produce ceramic matrix composite (CMC) refractory. Characterization and fabrication of Kankara clay matrix with reinforced grey cast iron particles were developed in this study. The CMCs were prepared by varying the percentage weight of the grey cast iron from 5% to 45% at intervals of 5%wt. The Aim of the research is to identify, process, and formulate some selected materials such asKaolin (Kankara clay) and Grey cast iron to produce kiln shelves, shelf bars, props that can withstand high temperature and maintain its structural integrity. To get performance results, test sample specimens were made from the CMC material, dried for 14 days and then subjected to firing at a temperature of 12800C using kerosene burner kiln which was found to be adequate in yielding hard, strong, stiff and smooth glossy effects. The grey cast iron was obtained at Metallurgical Development Centre (MDC), Jos, Plateau State of Nigeria and the Kankara clay was obtained at Kankara, Kastina state of Nigeria. Physical property test(Apparent porosity, water absorption, linear shrinkage and bulk density) were conducted as well as mechanical property tests (Hardness, tensile strength, compressive strength, Cold Crushing Strength). Chemical analyses of the materials were conducted in Pretoria and Durban, South Africa for x-ray diffraction (XRD), x-ray fluorescence (XRF), scanning electron microscopy (SEM) and Thermo Gravimetric analyzer (TGA). Casting method was used as a shaping method to produce experimental samples and subsequently the prototype of the products. The physical and mechanical properties of the produced composites were determined and the results obtained showed that there wasincrease in the hardness value, cold crushing strength, ultimate tensile strength and compressive strength of the developed composite up to 25% wt of grey cast iron which thereafter drops with increasing grey cast iron content. The optimum value of these properties are 94shores of Hardness value at 45%wt Grey cast iron, 13.32N/mm2, 1.87N/mm2, 7.15N/mm2 at 25%wt Grey cast iron (GCI) respectively. Also, there was an increase in bulk density with increase in the grey cast iron content with optimum value of 1.26g/cm3 at 0%wt GCI however, linear shrinkage, water absorption and apparent porosity reduces with increasing GCI content with optimum values of 0%, 13.47% and 22.41% respectively. The thermal analysis curve shows that the samples are stable until 7000CSummary of finding of the research shows that the utilization of Kankara clay and grey cast iron for the production of composite refractory was successfully carried out using 25%wt GCI developed into a good composite refractory.