| 摘要 |
Porous abrasive tools, e.g. wheels, comprise a non-metallic abrasive material bonded by a bond which incorporates, as a pore former, a water soluble crystalline refractory salt melting above 750 DEG C. which salt may either be dissolved out in use by an aqueous coolant, or leached out prior to use. Although fused aluminium oxide, silicon carbide, corundum or garnet may be employed, the most suitable abrasive is diamond grit, while the bond is wholly of metal or ceramic, or of metal and ceramic, and the refractory salt may be sodium chloride or sulphate, potassium chloride or carbonate, or calcium chloride, but is most suitably sodium pyrophosphate, and may be added to the bond-forming material in amounts up to 80% by volume. Suitable bonds are (a) 80% Cu powder and 20% Sn powder, (b) 10% Ag powder, 20% Sn powder and 70% Cu powder, (c) frit and cast iron, and (d) low melting glass powder. The tools are suitably made by hot-pressing at 650 DEG and 10,000 p.s.i. Specification 715,528 is referred to. |
