High-Hardness Solidified TiB₂-TiC Composites Prepared by Combustion Synthesis under High Gravity

Abstract:

Large-bulk TiB₂-TiC composite ceramics were prepared by combustion synthesis under high gravity. XRD, SEM and EDS results showed TiB₂-TiC composites were mainly composed of the fine-grained microstructures of TiC matrix in which a large number of the fine TiB₂ platelet grains were dispersed uniformly, whereas there discontinuously dispersed the ε-carbides with the enrichment of Ti atoms, and a few of isolated, irregular α-Al₂O₃ grains and Al₂O₃-ZrO₂ colonies were also observed at the boundaries of the eutectic microstructures. The results of properties indicate that with increasing mass fraction of B₄C+Ti+C in combustion systems, the relative density and fracture toughness of TiB₂-TiC composites are all among 97%~99% and 6.5~7.1 MPa·m^1/2, respectively, and the Vickers hardness and flexural strength are increased gradually to the maximum values of 28.6GPa and 615MPa, respectively. The achievement of full-density TiB₂-TiC composites benefited from the design of full-liquid SHS products and the introduction of high-gravity field, and high hardness of the composite ceramics resulted from the absence of intermediate borides and the achievement of stoichiometric TiC phases due to rapid solidification, whereas high flexural strength of the composite ceramics benefited from the homogenization and refinement of the microstructures due to the rapid separation of the liquid oxides and the rapid coupled growth of TiB₂-TiC.

• Periodical: Advanced Materials Research (Volumes 233-235)
• Pages: 1734-1739
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.233-235.1734
• Online since: May 2011
• Authors: Tao Ma, Zhong Min Zhao, Long Zhang, Xue Gang Huang, Liang Xiang Liu
• Keywords: Combustion Synthesis, Fine Grained Microstructure, High Gravity, Rapid Solidification, Tib₂-tic Composite

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