Texturing of mullite by templated grain growth with aluminum borate whiskers

Textured mullite was produced by templated grain growth with a mixture of mullite powder and aluminum borate (9Al2O3·2B2O3) whiskers. A gated doctor blade was used to align the whiskers in the c-axis in the mullite matrix during tape casting. When heated by themselves in air, aluminum borate whiskers formed α-Al2O3 at > 1400°C but were stable enough for templated mullite growth in a TiO2-doped mullite sintered at 1500°C. Starting with 3 wt.% TiO2 and 10 wt.% templates, an ∼90% textured mullite was obtained after 6 h at 1600°C. The <001> textured mullite was 97% dense and had a FWHM of 9.6° in the [001].