A Study On The Preparation, Structure And Properties Of β-Sialon Bonded Corundum Composite

Using brown corundum, white corundum and dense corundum as aggregate, taking aluminum powder, metallic silica powder, alumina powder as raw materials, β-Sialon bonded corundum composite was synthesized in-situ with the nitrogen atmosphere in 1420 ℃, 1450 ℃, 1500 ℃ and 1550 ℃. Through the test of samples, the influences of different corundum main-crystal phase, different temperature, closed nitrogen atmosphere and the flow of nitrogen atmosphere, and the aggregate of particle size distribution and pure powder on structure and performance of β-Sialon bonded corundum composite were compared. In addition, adding 2% Fe₂O₃ and TiO₂ respectively into the sample of β-Sialon/white corundum, analyze their influence on the composite.Test results show: the weight of the samples with white corundum main-crystal phase was rising constantly with the rise of temperature .But in 1550 ℃, the weight had a little decline because of volatilization of glass phase; Sialon crystal also had growed from short whisker to long column;Density and crushing strength had been on an upward trend. When different corundum was the main crystal phase, the nitridation effect of the samples with small size was more or less the same. But the performance of the sample with brown corundum main-crystal phase was better than others', when the size became big. Compared to the sample with particle-size distribution, the effect of nitrogen of the sample without distribution was better. However, its other mechanical properties were poor. Adding Fe₂O₃ alone to the sample with white corundum main-crystal phase, the rate of nitridation and density had decreased but crushing strength had increased significantly. The role of Fe₂O₃ may promote Al₂O₃ from aggregate surface as the tie linking Sialon combination phase and corundum Aggregate particles. After adding TiO₂, the overall performance of the sample had improved, so that it can serve as an effective additive. The excellent performance of samples with brown corundum main-crystal phase was not only with nitridation technology, but also with its internal impurities definitely. Not one or two impurities effected, but many impurities effected together. There existed gas reaction in the sintering process. When taking the technology of flow-nitrogen, we must pay attention to control the rate of flow of nitrogen, or the Sialon phase would lose, which would affect the overall performance of materials.