The two most common variations of tungsten carbide seal faces/ring are cobalt bound and nickel bound. the seal faces/rings of Nickel bound tungsten carbide is more corrosion resistant although the seal faces/rings of the cobalt bound tungsten carbide is more than adequate for most services. Neither is as good as alumina. a tungsten carbide seal face/ring has a very high compressive and tensile strength,a high modulus of elasticity. The mechanical seals with tungsten carbide seal faces or rings can be used in pumps operating in fluids with sands or solids.