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Titanium diboride ( TiB2) have been widely studied as one of the most promising engineering ceramics and refractory material because of its excellent physical and chemical properties such as high melting point,high modulus,low density and excellent electric conductivity.In addition,TiB2 ceramics exhibit unique properties of good wettability with liquid aluminum and good corrosion resistance,such properties make the titanium diboride and carbon ( TiB2/C) composites have been considered as the ideal cathode materials for Hall- Heroult cells to replace the traditional carbon cathode material.When combined with carbon,the titanium diboride and carbon ( TiB2/C) composites have many advantages.On one hand,the TiB2/C composites have good thermal shock resistance duo to the low thermal expansion coefficient and high thermal conductivity of TiB2 and carbon.On the other hand,carbon shows a good lubricity,so the TiB2/C composites exhibit good machinability and wear resistance ability,moreover,the carbon can eliminate the harmful effect of oxide impurities on the densification of TiB2 composites.Titanium diboride-carbon ( TiB2/C ) refractory composites were prepared by hot pressing sintering.The effects of the TiB2 content and hot pressing parameters on the mechanical properties and microstructures of composites were investigated.Three point bending test method was used to measure the flexural strength of TiB2/C composites,fracture toughness was evaluated by the single edge -notched bending test ( SENB),scanning electronic microscopy ( SEM,JSM-S3400) and X-ray diffraction were used to evaluate the microstructure of sintered materials on fracture surface and polished section.The bulk density of the TiB2/C composites was measured by the Archimedes s method.The TiB2 content and sintering parameters were found to have significant effect not only on the microstructures of composites,but also on the densification and mechanical properties.The experimental results show that the increase of the TiB2 content can improve the plastic flow ability of mixed powder during hot pressing,thus increase the relative density and mechanical properties of TiB2/C composites remarkably,the highest relative density of composites is 97.1% when the weight fraction of TiB2 is 90%.Both the relative density and mechanical properties of TiB2/C composites increase with the rise of sintering temperature,however,longer sintering time will lead to TiB2 crystal grain bigger,the abnormal grain growth and uneven microstructure decrease comprehensive properties of composites.Hence high sintering temperature and short sintering time are key factors to prepare dense TiB2/C composites with good mechanical properties.When hot pressed at 1950℃ for 60 min,TiB2/C composites with TiB2 content of 85wt% have the best comprehensive properties,the relative density,flexural strength and fracture toughness reach 97.21%,3.573 MPa.m1/2 and 210.07 MPa respectively.