Process for producing shaped bodies comprising fiber-reinforced ceramic materials
Process for producing shaped bodies comprising fiber-reinforced ceramic materials, where a green body is produced in a first step by introducing a press moulding composition into a mold, where the press moulding composition comprises carbon fibers and/or carbon filaments and pitch and/or resins which, when treated thermally and with the exclusion of oxidizing agents, form carbon-containing residues, the green body is cured in a second step by heating to a temperature of from 120° C. to 280° C. under pressure, the cured green body, also referred to as intermediate body, is carbonized in a third step by heating in a nonoxidizing atmosphere to a temperature of from about 750° C. to about 1100° C. to form a C/C body, wherein heating in the first, second and/or third step is at least partly effected by an electric current being passed through the pressable composition, the green body and/or the cured green body, shaped bodies produced according to this process and their use as brake disks, clutch disks and friction disks
1. A process for producing porous fiber-reinforced shaped bodies, where
a press moulding composition is introduced into a pressing mold, where the press moulding composition comprises carbon fibers and/or carbon fiber bundles and/or carbon filaments,
and pitches and/or resins which are thermally curable and capable of being carbonized in a first step,
the press moulding composition is cured by heating to a temperature of from 120° C. to 280° C. under pressure, in a second step to form a green body,
the green body is carbonized and/or graphitized in a third step by heating in a nonoxidizing atmosphere to a temperature of from about 750° C. to about 2400° C. to give a C/C body,
wherein heating in the second and/or third step is at least partly effected by an electric current being passed through the press moulding composition and/or the cured green body, during pressing.
2. The process as claimed in claim 1 , wherein, subsequent to the third step,
the C/C body is infiltrated with a liquid metal with retention of its shape in a fourth step, with at least partial reaction of the carbon present in the matrix of the C/C body with the metal to form carbides.
3. The process as claimed in claim 1 , wherein the electrical conductivity of the press moulding composition prior to or during the pressing operation is at least 0.1 S/m.
4. The process as claimed in claim 1 , wherein the electrical conductivity of the green body is at least 0.1 S/m.
5. The process as claimed in claim 1 , wherein the pressable composition is heated by passing electric current through it via the top and bottom surfaces of a pressing mold.