Gelcasting of alumina from acidic aqueous medium using acrylic acid

An aqueous gelcasting process for alumina using an acrylic acid monomer has been investigated. Concentrated aqueous alumina slurries with pH 3 were se t in moulds at 80 degrees C during 10-15 min by polymerisation of the monom er contained in it using ammonium persulphate as free-radical initiator. Th e green density maximum (57% TD, corrected for organic content) was obtaine d at similar to 6 wt% binder content, at which the green strength (by diame trical compression test) measured was 11.5 MPa. The green bodies with binde r content greater than or equal to 4 wt% were amenable to conventional mach ining operations such as lathing, milling and drilling. The total linear sh rinkage of 55 vol% A16SG alumina slurry was 1.4% during drying and 15-17% d uring binder removal and sintering to 97% TD. (C) 2000 Elsevier Science Ltd . All rights reserved.