JPS6424071A - Carbon material and its production - Google Patents

Abstract

PURPOSE:To rapidly produce a carbon material adequate for a magnetic disk substrate for high-density recording by mixing a carbon material such as particulate graphite and thermosetting resin which is turned by carbonization calcination to glassy carbon, subjecting the mixture to premolding and calcining the molding under specific conditions. CONSTITUTION:At least one kind of the first carbon material selected from the particulate or lumped graphite or carbon black (about <=1mu grain size) and the thermoplastic resin (furan resin, etc., and about 5-40mu grain size) which is turned to the glassy second carbon material by carbonization calcination are mixed and an org. thickener and defoaming agent are added to the mixture, then the mixture is premolded. The first carbon material is so compounded at this time that the volumetric ratio thereof after the carbonization calcination is 5-50% and the ratio of the spherical glassy carbon attains 3-10 times the area ratio after the calcination of the first carbon material and the non-spherical glass carbon. The perform is then subjected to precalcination at about 700-1,500 deg.C and is applied with an isotropic pressure of 1,000-3,000atm. in a 2,050-2,600 deg.C temp. range by which the perform is calcined. The high-strength carbon material which has excellent surface accuracy, is light in weight and has a small coefft. of thermal expansion and excellent heat resistance and corrosion resistance is thereby obtd.