Texturing Ca-α-sialon via strong magnetic field alignment

This paper reports a dense textured single Ca-α-sialon fabricated by strong magnetic field alignment (SMFA) during non-aqueous slip casting of α-Si₃N₄, CaCO₃, Al₂O ₃ and AIN starting powders, followed by reaction pres-sureless sintering at 1800°C, XRD analysis reveals that the orientation of the α-Si₃N₄ crystals occurs with the c-axis perpendicular to the magnetic field during slip casting. It is shown that the formation of the single Ca-α-sialon is complete within 5 min and nearly complete densification is achieved within 60 min. SEM observation reveals that the textured Ca-α-sialon is featured by the long-axis (c-axis) of large elongated grains perpendicular to the magnetic field. The texturing mechanism is attributed to the heterogeneous nucleation and epitaxially elongated growth on the initially oriented α-Si₃N₄ seeds. The prolonged sintering leads to a higher orientation as a result of the promoted grain growth.