Sintering of waste of superalloy casting investment shells as a fine aggregate for refractory tiles

Powders obtained by milling ceramics shells, already used as investment material in casting processes, were sintered to investigate their possible re-use in the production of ceramic refractories. The sintering behaviour of these powders, consisting essentially of silica and mullite, were analysed both in a heating run by conventional contact dilatometry and in an isothermal process via optical dilatometry. The mechanical properties of sintered composites formed with a matrix of fine powders and an inert coarse phase of the same material are evaluated and discussed in view of possible use in the production of refractory tiles.