FABRICATION OF POROUS CAST-IRON BONDED DIAMOND GRINDING WHEELS AND THEIR EVALUATION TO GRIND HARD-TO-GRIND CERAMICS

Porous cast-iron bonded diamond grinding wheels were fabricated and te sted, Diamond grains of #100/120 were used as abrasive grains. Atomize d cast-iron of various grain-sizes and carbon contents was used as bon ding material, The capsule-free hot isostatic press (HIP) method was e mployed to obtain high mechanical strength and high porosity, Grinding tests were conducted under constant pressure grinding (CPG) condition s to avoid influences of Young's modulus of different grinding wheels and stiffness of grinding machines, The grinding ratio, grinding force and specific grinding energy were evaluated for the new and other com mercial grinding wheels, Alumina and silicon nitride were ground for t he evaluation, Grinding wheels bonded by cast-iron of low carbon conte nt, i.e., 3.11 mass%, and finer grain size, i.e., less than 20 mu m, h ad higher grindability. Scanning electron microscopic observation show ed evidence of reaction between the diamond grains and the cast-iron p articles, i.e., and diffusion of carbon from the diamond grains to the cast-iron particles, The total volume of diffused carbon from diamond to cast-iron affected the grindability, The porous cast-iron bonded g rinding wheels showed an extremely higher grinding ratio and lower spe cific grinding energy than commercial resinoid wheels, vitrified wheel s, and non-porous cast-iron bonded wheels.