Fabrication and evaluation of C-ring strength of SiCf/SiC composite tube

Abstract

The SiCf/SiC composite tubes were manufactured by three different manufacturing methods: rotation CVI (chemical vapor infiltration), nanorod-assisted CVI, and forced CVI, and the C-ring compression strength of the tubes was evaluated. In the rotation CVI method, the supply route of the source gas greatly influenced the formation of a homogeneous microstructure, and supplying gas from both directions of the tube could improve the microstructure homogeneity. The longer the gas supply time from the inside to the outside, the better was the C-ring strength. In the nanorod-assisted CVI method, the existence of SiC nanorods increased the strength by 25% (338–429 MPa) and the macro-pore fraction by 44% (7.6% to 3.4%) compared to the conventional CVI tube. In tubes with large diameters (100 mm and 150 mm) made of forced CVI, meaningful strength values were measured even at values outside the range of 1\u2009<\u2009b/t\u2009<\u20092, which is the boundary condition of the C-ring strength in standard test method. Therefore, further evaluation is necessary.