Preparation and properties of C/SiC bolts via precursor infiltration and pyrolysis process

Abstract C/SiC composites with three kinds of preforms (carbon fiber stitched cloth, Type S; three‐dimensional fine woven pierced felt, Type 3D; carbon fiber needled bulk felt, Type N) were fabricated by precursor infiltration and pyrolysis (PIP) process, and then machined into bolts and nuts with nominal diameter of M8 by lathe and alloy screw tap, respectively. The thread shape and mechanical properties were investigated. The results show that the external thread shapes from Type 3D and Type N are better than that from Type S. The shear strengths of the nuts and the tensile strengths of the bolts from the three preforms are 67.38, 32.47, 48.99, 143.70, 159.20, and 95.90 MPa, respectively. The fracture mode of Type S bolts is external thread spalling, and those of the other two are bolt rupture. Therefore, the composite of Type 3D is a good choice for the bolts, and that of Type S for the nuts.