Fabrication and mechanical properties of three-dimensional carbon fibre reinforced mullite composites via sol-gel

Three-dimensional braided carbon fibre reinforced mullite composites (3D-BCf/mullite) were fabricated by SiO2-Al2O3 diphasic sol-gel technology. The results showed that active SiO2-Al2O3 composite powders could be prepared through sol-gel using AlCl3.6H(2)O, (CH2)(6)N-4 and SiO2 sol as starting materials. Al2O3-SiO2 composite powders were transformed to mullite after calcined at 1 300 degrees C under N-2 for 1 h. The density, flexural strength, and fracture toughness of 3D-BCf/mullite composites were 1.642 g/cm(3), 257.9 MPa and 12.2 MPa.m(1/2) respectively. It was the large quantities of pores in composites that resulted in low density and flexural strength of 3D-B C-f/mullite composites.