Combustion synthesis of refractory and hard materials: A review

Combustion synthesis is widely used for preparing various refractory and hard materials, including alloys, intermetallics, ceramics, and cermets. The unique reaction condition in combustion synthesis with extremely-high temperature and fast heating/cooling rate offers the products interesting microstructures and superior mechanical properties. In comparison with conventional powder metallurgy approaches, combustion synthesis exhibits the advantages of short processing time, less energy consumption, and lower cost, thus providing a more efficient way to produce refractory and hard materials. This article reviews recent progress in combustion synthesis of refractory and hard materials, with an emphasis on the results reported in the last decade. Both the synthesis of powders and direct fabrication of bulk materials are discussed. For the synthesis of powders, results in two aspects are reviewed, viz, synthesis of ultrafine and especially nano-sized powders by thermal reduction reactions or post chemical etching, and synthesis of nitride and carbide powders in air. For direct fabrication of bulk materials, two techniques are involved, viz, combustion synthesis with simultaneous densification assisted by a mechanical or gas pressure, and combustion synthesis casting in a high-pressure Ar atmosphere or in a high-gravity field. (C) 2012 Elsevier Ltd. All rights reserved.