Microstructures and mechanical properties of large-scale Al 2 O 3 /ZrO 2 (Y 2 O 3 ) self-growing ceramic plates prepared by combustion synthesis under high gravity

Abstract

By introducing ZrO 2 and Y 2 O 3 mixed powder into the thermit, the large-scale Al 2 O 3 /ZrO 2 (Y 2 O 3 ) self-growing ceramic plates were prepared from the melts through combustion synthesis under high gravity. The materials were mainly formed by randomly-orientated rod-shaped colonies with faceted structures consisting of a triangular dispersion of orderly nanosubmicron ZrO 2 fibers in the Al 2 O 3 matrix, surrounded by the boundary regions that contained the coarse irregularshaped ZrO 2 and Al 2 O 3 phases. The flexural strength of the self-growing ceramic plate was excellent (measured 1278MPa), and it was not only attributed to the small critical defect size caused by the fine eutectic microstructures, excellent bonding between the Al 2 O 3 /ZrO 2 phases and the thin inter-colony regions, but also more importantly dependent on high fracture toughness of 13.7 MPa·m 1/2 , which is controlled by residual compressive stress toughening in the colonies, transformation induced toughening and transformation induced microcrack toughening mechanisms in intercolony regions during crack propagation.

Combustion Synthesis: An Update

“…Some of the recent results included the preparation of Al 2 O 3 /ZrO 2 self -growing composites [75,76] (Fig. 11.4 ).…”

“…This orientation of the microstructure has given a signifi cant rise in the fl exure strength, fracture toughness, and other mechanical properties. The experimentation and production of Al 2 O 3 /ZrO 2 has been further pursued by studying the infl uence this ceramic has when additives are mixed with it during CS [76] .…”

The damage strain field analysis of triangular symmetrical composite eutectic

“…In the directional solidification oxide eutectic multiphase ceramics system, the multiphase ceramic based on triangular symmetrical eutectic has the best mechanical properties under room temperature and high temperature (Lorca and Orera, 2006;Pena et al, 2002;Lee et al, 2001;Zhao et al, 2008). Its microstructure and mechanical features are as follows:…”