The strength and oxidation of reaction-sintered silicon nitride
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- Evans, A.G. & Davidge, R.W. J Mater Sci (1970) 5: 314. doi:10.1007/BF02397783
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The structure of reaction-sintered silicon nitride is studied using scanning electron and optical microscopy at various stages during nitriding, for a range of nitriding and compacting conditions. The strength is then evaluated and interpreted in terms of the microstructure. It is found that fracture always occurs in a brittle manner by the extension of the largest pores. The effects of prolonged annealing in air above 1000† C on both the structure and strength are investigated. At 1400† C, cristobalite is formed. If the temperature is then maintained above 250† C, the strength is enhanced, but below this temperature the oxide layer cracks and reduces the strength.