PREPARATION OF HIGH SINTERABLE LITHIUM METASILICATE

A new approach has been developed to produce sinterable lithium metasilicate in order to fabricate high density ( greater than 90% TD) pellets by cold compaction and sintering. Lithium carbonate and silica are intimately milled, spray-dried, pre-calcined and calcined. Precalcination under wet air at about 430 degree C has led to the discovery of a hexagonal X-phase, the formation of which is the key to the process. The X-phase can in fact easily be transformed by a calcination below 600 degree C into a high reactive metasilicate containing no disilicate nor orthosilicate, which is not possible by direct calcination. The effects of temperature, time and atmosphere on the formation of the X-phase are discussed.