Compsn. for crack-free, dimensionally accurate ceramics

摘要

Thermoplastic compsn. for use in the mfr. of ceramic shaped articles comprises: (A) 40-65 vol% of a sinterable, inorganic, non-metallic powder; (B) 35-60 vol% of a binder comprising (B1) 70-90 wt.% of a polyoxymethylene homo- or co-polymer contg. up to 10 mol% comonomer units; and (B2) 10-30 wt.% of (i) a polyoxymethylene copolymer with a comonomer content of 20-99 mol% poly-1,3-dioxolane, poly-1,3-dioxane or poly-1,3-dioxepan or (ii) a polymer which is homogeneously dissolved in (B1) and/or a polymer which is dispersed as particles of ave. size below 1 micron in (B1); and (C) 0-5 vol% of a dispersing aid. Also claimed is the de-bindering subsequent to injection moulding or extrusion by treating at 20-160 deg.C for 0.1-24 hrs. in a gaseous acid-contg. atmos. when (B2(i)) is used or by treating in such at atmos. at 20-180 deg.C for 0.1-24 hrs., followed by heating at 250-500 deg.C for 0.1-12 hrs. when (B2(ii)) is used. Powder (A) is pref. Al203, Zr02, Y203, SiC, Si3N4, TiB and/or AlN. Component (B2(ii)) of the binder is pref. an aliphatic polyurethane, aliphatic non-crosslinked polyepoxide, poly(2-6C alkylene oxide), aliphatic polyamide and/or a polyacrylate.