In situ nitriding reaction formation of β-Sialon with fibers using transition metal catalysts

beta-Sialon powder containing nanofibers was synthesized at 1300-1450 degrees C for 5 h in nitrogen by using transition metals (Fe, Co and Ni) as catalysts. Such synthesis conditions obviously reduced the nitriding temperature (similar to 100 degrees C) of beta-Sialon and increased the degree of nitridation. Observations from the weight gain rates of specimens relative to the content of catalysts suggest that the nitridation process was accelerated sharply via the addition of 0-2.5 wt% metallic catalysts. In addition, the amount of nanofibers of beta-Sialon found in the specimens increased with the amount of transition metals, which was governed by the VLS formation mechanism with the help of transition metals. It could be concluded that transition metals not only greatly accelerated the nitridation of Si but also facilitated the formation of beta-Sialon nanofibers in the specimens, as the formed metal-containing liquid greatly enhanced the amount of vapor generation.