β-Si₃N₄ whiskers prepared by heating a mixture of B₂O₃ and α-Si₃N₄

Abstract

Heating a mixture of α-Si₃N₄ and B₂O₃ at 2150 °C for 1 min under N₂ at a pressure of 0.85 MPa was found to generate β-Si₃N₄ plate whiskers with widths of ∼10 µm, thicknesses of ∼0.2 µm and lengths greater than 2 mm. Boron nitride powder, β-Si₃N₄ platelet grains and a small amount of α-SiC grains were also obtained. Single crystal X-ray diffraction demonstrated that the whiskers were elongated in the c-axis direction and additional tests indicated elastic deformation of the whiskers.