Powder Processing Science and Technology for Increased Reliability

Issues concerning powder consolidation methods compatible with the colloidal approach and issues associated with other powder processing steps, viz., den-sification and microstructural control, are presented with regard to research directions leading to more reliable ceramics. 1. Introduction With their multiplicity of elemental combinations and crystal structures, ceramics exhibit unique properties that are still being uncovered. Ceramics are needed to implement many technology scenarios ranging from advanced heat engines to transmission of information. Ceramic-processing technology has advanced little beyond the needs of functional ceramics. Traditional ceramic processing inherently lacks a clear approach for controlling microstructure het-erogeneties and microstructure uniformity. Property variability and, thus, ambiguous engineering reliability stem from uncontrolled microstructures. Engineering reliability is a matter of processing reliability. Most forming methods are generally unacceptable for ceramics. Their brittle nature precludes deformation methods commonly used for metals. Melt casting produces friable ceramics because of, in part, uncontrolled grain growth during solidification. Some advanced ceramics,