8 - Other Ceramic Powder Fabrication Processes

Abstract

This chapter is devoted to the other ceramic powder fabrication processes. These methods include spray drying, spray roasting, freeze drying, metalorganic decomposition, sol-gel synthesis, and melt and flux solidification. There are many similarities between spray drying, spray roasting, and freeze drying that start with atomization of a liquid followed by drying (and thermal decomposition) or freezing. The earliest routes for forming ceramics from sol-gel solutions involved the precipitation of metal oxide particles solutions. Sol-gel synthesis is particularly different than the precipitation because an aggregate (or polymer) network is formed. This gel can be dried (or spray dried) to form a ceramic powder. Use of sol-gel synthesis to make films and fibers has also been superficially discussed. Melt and flux synthesis is used to produce the largest ceramic powders, which are often used for abrasives. Spray drying is also a method of ceramic powder production that uses either a concentrated metal salt solution, a powder dispersion (a sol) with a polymeric binder, or a gel solution as a feed material.