Modification of Oxidation Resistance for Low Density Carbon-bonded Carbon Fiber (CBCF) Composite

Perhydropolysilazane (PHPS) derived SiON coatings were deposited on surface of chopped carbon fiber in carbon-bonded carbon fiber (CBCF) composite by precursor infiltration-thermal (PIT) conversion method. Morphology and elemental analysis of SiON coating were investigated by SEM and EDS. The results show that the coatings are uniform, dense and mainly composed of Si, O and N elements. Meanwhile, the coating gets thicker with the increasing concentration of PHPS, but tends to agglomerate in the opening pores, especially when the concentration of PHPS reaches 10wt% and 20wt%, obvious agglomeration emerges in the opening pores. Meanwhile, cracks appear in the coating on the carbon fibre surface. Finally, oxidation resistance of CBCF composites treated by SiON coating was studied by TGA analysis and isothermal oxidation assessment. The results show that SiON coatings deposited on the carbon fiber surface in CBCF composite can remarkably enhance the oxidation resistance of CBCF, and the oxidation resistance increases with the increasing concentration of PHPS.