Fundamental friction and wear properties of new porous carbon materials: Woodceramics

Woodceramics are new porous carbon materials obtained from wood or woody materials impregnated with phenol resin, and carbonized in a vacuum furnace at high temperatures. During the carbonizing process, the wood or woody material changes to soft amorphous carbon and the impregnated phenol resin changes to hard glassy carbon. The purpose of this investigation is to analyse the fundamental friction and wear properties of woodceramics in sliding contact with several materials. It then discusses the possibility of practical use of woodceramics as friction materials. The following principal results were obtained; (1) Friction coefficient of woodceramics decreases from 0.45 to 0.15 with increasing carbonizing temperature from 400 degrees C to 700 degrees C when unlubricated in air, (2) Woodceramics carbonized at 800 degrees C and 2000 degrees C have consistently low friction coefficient (mu = 0.13 - 0.15) when unlubricated in air, impregnated with base oil, and in water, (3) Unless the contact pressure exceeds a critical value, the specific wear rate of woodceramics does not exceed 10(-8) mm(2)/N, which is low enough to allow woodceramics to be used in practical applications such as dry rubbing bearings, wet friction materials in automobile clutches, etc.