The mechanical properties and failure behaviour of carbon/phenolic composites were investigated. Carbon/phenolic composites were fabricated by an infiltration of phenolic resin into 8 harness satin woven fabric of PAN-based carbon fibers. Tensile properties of carbon/phenolic composites for with-laminar specimens in 0°, 45° and 90° directions were measured at temperatures ranged from 25℃ to 700℃ under nitrogen atmosphere. Tensile failure of carbon/phenolic composites in with-laminar/0°and 90°warp directions was occurred by the failure of carbon fibers. While, the tensile failure of carbon/phenolic composite in with-laminar/45° warp direction was occurred by the pull-out of fibers. Tensile strengths of carbon/phenolic composites in with-laminar/0° and 90° warp directions were measured as 750 MPa and 510 MPa, which were lower than the estimated tensile strength of 1190 MPa by rule-of-mixture. The reason for lower measured tensile strength was analyzed that the effective fiber volume fraction was reduced due to failure of fibers at undulation parts. In addition, the tensile strength of fiber bundle became lower than the ultimate tensile strength of fiber following the Weibull statistical distribution. The bundle strength was calculated about 87% of ultimate tensile strength of fiber using Weibull distribution function. Interfacial shear strength at fiber/matrix interface of carbon/phenolic composites was calculated about 20 MPa from the tensile test in with-laminar/45°warp direction. The decrease of tensile strength of carbon/phenolic in with-laminar/45° warp direction with increasing temperature was analyzed due to a degradation of matrix strength by thermal decomposition of phenolic resin. The decrease of tensile strength of carbon/phenolic composites in with-laminar/0°warp direction was analyzed due to the thermal residual stress originated from the thermal expansion mismatch between carbon fiber and phenolic resin matrix in longitudinal direction.
