EFFECTS OF POWDER PROCESSING ON THE CHARACTERIZATION OF MAGNESIA DERIVED FROM ALKOXIDE PRECURSORS .1. PREPARATION AND CHARACTERIZATION OF POWDERS

Magnesia powders have been prepared via alkoxide sol-gel and alkoxide- hydrolysis processes. Gel-derived powders exhibit porous aggregates, a nd extensive hard agglomerates are regarded as an intrinsic nature of gel powders; the morphology of the powders obtained from the hydrolysi s-precipitate route is a function of water content and retains highly agglomerated particles, suggesting that localized microgels are formed during processing. However, a simple modified sol gel approach propos ed to synthesize fine-sized powders with a narrower size-distribution and with less hard agglomerates, has been shown to be feasible. The th ermal behaviour and crystallinities of as-prepared powders are similar in all cases, however, there exists a significant difference in parti cle morphology. The obtained powders have been characterized and compa red in the Part I of this work. Their compaction and sintering behavio ur will be reported in Part II.