Effects of fiber-types on braking behavior of carbon–carbon composites

The effects of fiber-types (PAN-T300 (CF), PAN-oxidized fiber (OF)) on the friction and wear behavior of C/C composites were investigated. The C/C composites were fabricated by densifying porous needle-punched felts with isothermal chemical vapor infiltration to 1.40 g/cm3 followed by phenolic resin impregnation and carbonization till the ultimate density of about 1.75 g/cm3. Carbon fiber/pyrocarbon interfacial strength was measured by single fiber push-out test. And the flexural strength compressive strength of the composites was tested. The braking behavior was investigated by modeling normal braking conditions of aircraft. The fiber/matrix interfacial strength of the OF-derived composite is higher and the flexural strength and compressive strength is lower than that of the CF-derived composite. The needle-punched felt made from OF, result in C/C composite with higher and much more stable friction coefficient, but higher mass wear, than the composites with the porous preform made from CF. Combining fracture of composite and carbon fiber/matrix interface, a modified friction mechanism is suggested that a suitable flexural strength of the composite and carbon fiber/matrix interfacial strength favors formation of friction films. The friction film can result in higher and more friction coefficient.