| 摘要 |
A shaped abrasive body comprises graphite-free diamond particles substantially uniformly embedded in a matrix which forms a bond with diamond, is a good oxygen getter, and has a mechanical strength approaching that of diamond. The body is produced by mixing the diamond particles with the getter, subjecting the mixture to a pressure at which graphitization is inhibited, e.g. 45,000 atmospheres, and then heating to a point at which the matrix melts, e.g. 1500-1900 DEG C., preferably 1750-1800 DEG C., cooling below the graphitization temperature and releasing the pressure. A suitable diamond powder is one in which 80.5% comprises particles of 15-30 m , 16.5% of 4-8 m and 3% of 0.5-1.5 m , while suitable getters are titanium, vanadium, zirconium, chromium, silicon, and alloys and mixtures thereof. In particular, a preferred mixture consists of 16% silicon and 84% of such a diamond powder which has been cleaned either by heating at 400 DEG C. in a molten potassium nitrate and hydroxide mixture, or by heating first with 50% hydrochloric acid and then with sulphuric and hydrofluoric acid. The compact may be formed into tools or crushed to 100-240 mesh powder and used to form resin-bonded wheels. |
