Tungsten carbide is harder than sapphire and retains a superior edge after extensive use. Tungsten carbide is not a metal alloy but the product of powder metallurgy; very fine grains of two materials are mixed and fused under high temperature and pressure.
Tungsten carbide is made by blending micron-sized tungsten carbide and cobalt powders, then compacting the mixture in a mold and sintering the molded part at a temperature high enough to cause the cobalt to flow. During this process, the cobalt fills the voids between the tungsten grains and thoroughly coats each grain. When the cobalt solidifies, it cements; the grains together, forming a dense composite. Cemented carbides get their hardness from the tungsten grains and their toughness from the tight bonds produced by the cementing action of the cobalt metal. By varying the amount of cobalt we can change the hardness, wear-resistance, and toughness (shock resistance) of the carbide to suit your particular Tungsten Carbide needs.
Because of the nature of tungsten carbide, there is a minimum section thickness that can be obtained. Hence, a lot of tungsten carbide-made tools are fabricated, always referred to as industrial teeth, for all kinds of applications. Tungsten carbide rotary burr is one of them.