ZrO 2 -Al 2 O 3 -SiC W composite powder mixtures were prepared by carbothermal reduction of natural silicates (e.g., zircon, sillimanite and kaolin). Activated charcoal was used as the reducing agent. The reactions were carried out in a graphite furnace at 1650°C in argon atmosphere at a positive pressure of 0.15 MPa. XRD investigation of the product phases confirms the completion of the reaction and the phases were identified as monoclinic zirconia, tetragonal zirconia, α-alumina and β3-silicon carbide. SEM investigation of the powders reveals the whisker morphology of β-silicon carbide. It was observed that a small amount of zirconia was present in tetragonal form in addition to monoclinic form which could be due to fine particle size of the starting powder.

L. Mariappan

Papers

In situ preparation of ZrO2-Al2O3-SiCW ceramic composite powder mixtures by carbothermal reduction of silicate minerals