Fabrication of three-dimensional carbon fiber- reinforced Si_3N_4 composites by infiltration of slurry and organosilicon polymer

摘要

Three-dimensional (3D) carbon fiber reinforcedSi_3N_4 composites have been fabricated using slurry infiltrationand repeated infiltration of organosilicon (polysilazane) resin.Volume fractions of the fiber and Si_3N_4 powder of the slurry-infiltrated body were about 42 and 32 percent, respectively. Openporosity was decreased from 26 percent after the slurry infiltrationto approximately 9 percent after the repetition of the polysilazaneinfiltration and pyrolysis. The relative density of the body whichunderwent the pyrolysis of polysilazane at 1873 K reached 89.4percent after 6 cycles. However, the highest flexural strength andfracture toughness were obtained at a pyrolysis temperature of1673 K. Further reduction of open porosity to less than 2 percentwas accomplished by hot-pressing at 1873 K. The maximumvalues of flexural strength and fracture toughness were 360 MPaand 9.8 MPa?m~(1/2), respectively.