Surface Properties and Weibull Modulus of Silicon Carbide Kaolin Composites Improved by Adding Alumina

Abstract

Refractory ceramics were prepared from Silicon Carbide (SiC) as a main phase bonded with different weight percentages of Iraqi White Kaolin (20, 40, 60 and 80 wt%). After that, two weight percentages of micro and Nano size of alumina (5wt %) were added to all SiC-Kaolin mixtures. The samples were shaped by the axial pressing method after mixing well, then dried and Fired at 13000°C. The structural and mechanical properties were measured such as atomic force microscope AFM and diametrical strength (Weibull modules). AFM showed that Adding 80wt% Kaolin without adding alumina leads to reducing the surface roughness, average grain size diameter, and Root main square (RMS)nm from 210.9nm to 93.30nm, from 814.175nm to 509.3nm and from 377.0 to 100 nm. Adding micro and Nano Al2O3 with a ratio of 5wt% led to a reduction the the surface roughness, average grain size diameter, and Root main square (RMS)nm for Micro alumina from 93.30 nm to 84.06nm, from 509.3 to 498.9 nm and from 100 to 87.15 nm. Also for Nano alumina from 93.30 to 35nm, from 509.3 to 498.9nm, and from 100 to 41.8 nm. Weibull modules showed The optimal values for the prepared specimens in terms of specimen homogeneity and the best mechanical properties were for the mixtures consisting of 20 wt% of kaolin, 80 wt% of silicon carbide, and 5 wt% of nano Alumina. The importance and aim of this work is to prepare of refractory ceramic for oil industry applications. and improve the properties of refractories by using silicon carbide as a base material bonded with Kaolin in different ratios, then studding the effect of Micro and Nano Alumina on the properties of the refractory to choose the ratio to optimum for this application.