1987 Volume 7 Issue 1 Pages 29-40
The 2: 1 type clay minerals of pyrophyllite and talc were converted into nitrides by carbothermal reduction. The mixtures of the minerals and carbon black were heated at 1200-1600°C in an N2 flow. Pyrophyllite was converted into β-sialon and α Si3 N4. As oxides, mullite, α-quartz, and cristobalite were detected. On the other hand, α and β-Si3 N4 were obtained from talc. MgSiN2 and Si2 N2 O were also formed as intermediates. Forsterite and enstatite were detected as oxides. The variation in the compositions of the products suggests that both the minerals were converted into the nitrides via the decomposition to the oxides and their subsequent reduction.