The equilibria of Ta-W-Al-Si-O system at 1200 °C

Abstract Solid reactions among Ta-W-Al-Si oxides are discussed and the phase compatibilities of these oxides at 1200 °C have been investigated. The results showed that complex oxides of Ta 22 W 4 O 67 , Ta 2 WO 8 , Ta 16 W 18 O 94 , Al 2 W 3 O 12 and AlTaO 4 could be formed by solid reactions. Liquid phase formed by Al 2 O 3 -WO 3 in WO 3 -SiO 2 -Al 2 O 3 benefits the mullitization reaction, thus mullite can be formed at 1200 °C in ternary system. Solid solution with a formula of (1-x)Ta 2 O 5 ·xWO 3 was formed, and up to 25.0% SiO 2 and 6.0% Al 2 O 3 can be dissolved in the solid solution. Liquid phase first appeared in the Ta 2 O 3 -WO 3 -Al 2 O 3 ternary system at 1300 °C in the WO 3 -rich corner. As the temperature increased, the liquidus area expanded towards the Al 2 O 3 - and the Ta 2 O 5 -rich corners.