Microstructure and Mechanical Properties of ZrB_2/Alumina/Mullite Composite Synthesized by Combined SHS and Direct Consolidation

摘要

A highly dense object of ZrB2/alumina/mullite composite was synthesized via combustion synthesis combined with a direct consolidation technique from a blend of zircon, aluminum, and boron oxide powders. The influences of preheating temperature; Al particle size; and compaction load on porosity, microstructures, and mechanical properties of final products were investigated. Heating the sample prior to ignition led to development of cracks and coarser particle sizes, while increasing or decreasing the particle size of Al more or less than 37 mu m led to inhomogeneous microstructure and cracks formation. Immediate application of 292 MPa contributed to a crack-free product of 1040 HV hardness and less than 1.0 vol% porosity with uniform microstructure. Detailed thermodynamic study of the combustion reaction is discussed.