| 摘要 |
PROBLEM TO BE SOLVED: To obtain a material for brake, having strong abrasion in spite of high coefficient of dynamic friction, excellent in heat stability in non-oxidizing atmosphere and scarcely causing deterioration and deformation by heat evolution in brake operation. SOLUTION: This material for brake comprising a carbon fiber-reinforced carbon composite material has the following characteristics: (i) volume percentage of carbon fiber is 30-65 vol.%, (ii) crystallite size Lc (002) is >=10 nm and tensile modulus is >=380 GPa and heat conductivity in measuring at room temperature is >=110 W/mK and (iii) isotropic or anisotropic region in optical structure of matrix carbon has fine mosaic structure. The measured value of frictional coefficient at 2.5-25.0 m/sec relative sliding velocity of the material for brake is 0.20-0.60. The carbon fiber-reinforced carbon composite material is produced by impregnating optical isotropic pitch obtained by nitrating pitch-based heavy oil as matrix carbon precursor into raw material carbon fiber or carbon fiber structure, carbonizing the impregnated pitch and as necessary graphitizing and heat-treating the carbonized material. |
