Hot forging of mullite-based ceramics prepared from kaolin-alumina

Mullite-based ceramics prepared from a mixture of kaolin and alumina were plastically deformed in uniaxial compression tests at high strain rates (= 10−2–10−3 s−1) at 1450° and 1500°C. Deformation occurred with barreling in tests that used SiC platens coated with h-BN. This study shows that more-suitable lubricants and molds (platens) must be found, to reduce friction between the mullite-based ceramics and molds. However, this hot-working method can be used to give a fine, textured surface to mullite-based ceramic substrates for polycrystalline silicon thin-film solar cells.