Accelerated densification of porous carbon - by impregnating with decomposable hydrocarbon, then heating under pressure

摘要

Accelerated densification of a porous carbon substrate (A) comprises decomposing, in the presence of (A), pitch, acenaphthylene (I), phenanthrene or their mixts. at high temps. and pressure. Decompsn. is carried out in a closed reactor, allowing release of hydrogen as it forms, the walls of the reactor being sufficiently flexible to adapt to the vol. of the liq. phase. Pref. pitch, or other hydrocarbon contg. free C atoms is used. Pref. a mixt. of 5-40(30) wt.% (I) and pitch is used with C:H atom ratio over 1.4, contg. below 0.1% quinoline insolubles; about 20% toluene insolubles; below 0.2% sulphur and below 0.1% each oxygen and nitrogen. This material is made by separately dry-grinding (I) and the pitch to particle size below 100 microns, mixing the powders, then degassing at about 140 deg.C with continuous agitation until residual pressure in the reactor is about 5 mm. An appts. for the process is also claimed. The dense carbon articles produced have high mechanical strength and abrasion resistance at high temp., and are useful as electrodes, car or aircraft brakes, and medical prostheses. Materials of high free carbon content can now be used without problems of warping the substrate walls.