Characterization of hot pressed SiC whisker reinforced TiB2 based composites. (December 2016)

• Record Type: Journal Article
• Authors: Farhadi, Kiumars; Sabahi Namini, Abbas; Shahedi Asl, Mehdi; Mohammadzadeh, Ahad; Ghassemi Kakroudi, Mahdi
• Is Part Of: International journal of refractory metals & hard materials. Volume 61(2016:Dec.)
• Page Start: 84
• Page End: 90
• Publication Date: 2016-12
• Subjects: TiB2 -- SiC whiskers -- Hot pressing -- Densification -- Hardness -- Fracture toughness; Heat resistant alloys -- Periodicals; Refractory materials -- Periodicals; Metallography -- Periodicals; Alliages réfractaires -- Périodiques; Matériaux réfractaires -- Périodiques; Métallographie -- Périodiques; Heat resistant alloys; Metallography; Refractory materials; Periodicals; Electronic journals; 669.73
• DOI: 10.1016/j.ijrmhm.2016.08.004
• Languages: English
• ISSNs: 0263-4368

Abstract

Abstract: TiB2 –SiC ceramic composites, with different contents of SiC whiskers (SiCw ), as a ceramic sinter-additive, were prepared by the hot pressing process at 1850 °C for 2 h under a pressure of 20 MPa. For comparison, a monolithic TiB2 ceramic was also fabricated under the identical temperature, pressure, atmosphere, and holding time by the hot pressing process. The effects of fabrication process and SiC whiskers on microstructural features, phase evolution and mechanical properties were investigated. Hardness measurements revealed an initial increase in hardness for TiB2 –SiC compared to TiB2 . Also the improvement of the fracture toughness was attributed to the toughening and strengthening effects of SiC whiskers such as crack deflection. The results showed that promoted densification of TiB2 –SiC ceramic composites is due to addition of SiC whiskers and reduction of oxide impurities by reacting with SiC whiskers and removing them from the surface layer of TiB2 particles. The reaction between TiB2 particles and SiC whiskers led to in-situ formation of TiC phase in the matrix as well. In general, it is concluded that the sinterability of TiB2 -based composites was remarkably improved by introducing SiC whiskers compared to the single phase TiB2 ceramic. Highlights: The relative density of TiB2 ceramics was increased by introducing SiC whiskers. Removing oxide impurities promoted densification by minimizing grain coarsening. In higher SiC content, the reaction between TiB2 and SiC led to in situ TiC phase. SiC whiskers led to higher fracture energy dissipation during the crack propagation.