How are silicon carbide and aluminum oxide used in grinding wheels?

In the context of machine tools, silicon carbide and aluminum oxide are the primary manufactured abrasives used to create grinding wheels.1

To manufacture these wheels, abrasive granules of selected sizes are mixed with a bonding agent—such as clay, resin, rubber, shellac, or silicate of soda—and then fused together through baking or firing. The resulting wheel's grade, or hardness, is determined by the specific ratio of the bonding agent to the abrasive material.1

These wheels function as self-sharpening tools: as the wheel is used, dull abrasive grains break away to expose fresh, sharp grains underneath. Silicon carbide is noted for its extreme hardness and specific fracture characteristics that make it highly effective for grinding applications. Similarly, aluminum oxide is valued for its high strength and hardness, and it is commonly utilized in the production of grinding wheels and sandpaper grits. These abrasive tools are essential for shaping or changing the dimensions of hard materials, typically metals, by rotating at high speeds to remove material through contact.1234