Formation of nano SiC whiskers in bauxite–carbon composite materials and their consequences on strength and density

Abstract

SiC whisker is excellent in characteristics such as specific strength and chemical stability, and is useful as a composite reinforcing material. In this paper, the effect of the formation of in situ nano SiC whiskers on strength and density of bauxite–carbon composites was studied. Samples were prepared composed of 65 wt.% bauxite, 15 wt.% SiC-containing material, 10 wt.% coke, 10 wt.% resole and different values of silicon additives. The pressed samples were cured at 200 °C (2 h) and fired at 1100 °C and 1400 °C (2 h). XRD, SEM, TEM, EDX, FTIR and STA were used to characterize the samples. These characterizations indicated that SiC nano whiskers, 50–90 nm, are single crystalline β-SiC with mechanism of the formation VLS. So, firing temperature is an important factor. As, SiC nano whisker was formed at 1400 °C and improved CCS values up to four times in sample containing 6 wt.% ferrosilicon.