Effect of TiB2 on Micro structure Evolution and Mechanical Properties of SiC-B4C-TiB2 Composite Ceramics
SiC-B4C-TiB2 three-phase composite ceramics were prepared by using pressureless solid-phase sintering,with SiC,B4C,TiO2 and C as raw materials.It is found that TiO2 can be completely converted to the TiB2 during the sintering process.Simultaneously,densification of the SiC-B4C composite ceramics during sintering was promoted by the increase in the content of TiB2.The maximum relative density,bulk density and apparent porosity of the composite ceramics with 12 vol.％TiB2 reached 97.82％,3.12 g·cm-3 and 2.6％,respectively.Mechanical properties of the composite ceramics are positively correlated with their relative density.Flexural strength,Vickers hardness and fracture toughness of the samples reached(491±24)MPa,(30.1±0.8)GPa and(5.17±0.23)MPa·m1/2,respectively.Toughening mechanism of the SiC-B4C-TiB2 three-phase composite ceramics was dominated by the toughening of residual thermal stresses.Mechanisms such as crack deflection and immobilisation of diffuse particulate phases were present to achieve synergistic toughening.
NETL
NSTL
万方数据
