B4C–TiB2 composites fabricated by hot pressing TiC–B mixtures: The effect of B excess. Issue 9 (1st May 2022)

• Record Type: Journal Article
• Authors: Zhao, Jun; Tang, Chenjun; Li, Qinggui; Liu, Zetan; Ran, Songlin
• Is Part Of: Ceramics international. Volume 48:Issue 9(2022)
• Page Start: 11981
• Page End: 11987
• Publication Date: 2022-05-01
• Subjects: Boron carbide -- Titanium diboride -- Mechanical properties -- Microstructures; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2022.01.047
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Previous research have reported that B4 C–TiB2 composites could be prepared by the reactive sintering of TiC–B powder mixtures. However, due to spontaneous oxidation of raw powders, using TiC–B powder mixtures with a B/TiC molar ratio of 6: 1 introduced an intermediate phase of C during the sintering process, which deteriorated the hardness of the composites. In this report, the effects of B excess on the phase composition, microstructure, and mechanical properties of B4 C–TiB2 composites fabricated by reactive hot pressing TiC–B powder mixtures were investigated. XRD and Raman spectra confirmed that lattice expansion occurred in B-rich boron carbide and Bx C–TiB2 (x > 4) composites were obtained. The increasing B content improved the hardness and fracture toughness but decreased the flexural strength of Bx C–TiB2 (x > 4) composites. When the molar ratio of B/TiC increased from 6.6:1 to 7.8:1, the Vickers hardness and the fracture toughness of the composites were enhanced from 26.7 GPa and 4.53 MPa m 1/2 to 30.4 GPa and 5.78 MPa m 1/2, respectively. The improved hardness was attributed to the microstructural improvement, while the toughening mechanism was crack deflection, crack bridging and crack branching.