Low pressure hot pressing of B_4C matrix ceramic composites improved by Al_2O_3 and TiC additives

摘要

B_4C matrix ceramic composites toughened by Al_2O_3 and TiC were prepared by low pressure hot pressing. The relative density, Vickers hardness, fracture toughness and flexural strength of the new fabricated composites were measured. Microstructure observations of the fracture surfaces and the indentation cracks of the B_4C matrix ceramic composites were analyzed, and an X-ray diffraction phase analysis was performed. The experiment results showed that chemical reactions took place during the low pressure hot pressing process and resulted in the B_4C/Al_2O_3/TiB_2 composite. The densification rate of the B_4C matrix ceramic composites was enhanced and the mechanical properties were improved via the introduction of Al_2O_3 and TiC additives. The Vickers hardness, fracture toughness and flexural strength of the composite with the addition of 4.7 wt.% Al_2O_3 and 10 wt.% TiC were 24.8 GPa, 4.8 MPa m~(1/2) and 445 MPa, respectively.