There are two forms of WC, a hexagonal form, α-WC (hP2, space group P6m2, No. 187), and a cubic high-temperature form, β-WC, which has the rock salt structure. The hexagonal form can be visualized as made up of hexagonally close packed layers of metal atoms with layers lying directly over one another, with carbon atoms filling half the interstices giving both tungsten and carbon a regular trigonal prismatic, 6 coordination. From the unit cell dimensions the following bond lengths can be determined; the distance between the tungsten atoms in a hexagonally packed layer is 291 pm, the shortest distance between tungsten atoms in adjoining layers is 284 pm, and the tungsten carbon bond length is 220 pm. The tungsten-carbon bond length is therefore comparable to the single bond in W(CH3)6 (218 pm) in which there is strongly distorted trigonal prismatic coordination of tungsten.

Molecular WC has been investigated and this gas phase species has a bond length of 171 pm for 184W12C.


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The tungsten carbide powder and powdered cobalt metal are mechanically mixed to form a uniform combination. To this combination is added a polymer or wax that acts as a mechanical binder in the pre-sintered stage. A carefully measured volume of this combined powder is compressed by a double acting press to form the tungsten carbide ball blank, or pre-form. The binder is removed by placing the preformed parts in a vacuum chamber and raising the temperature. The binder out gasses and is trapped down stream as a liquid.

Next, the combined tungsten carbide and cobalt pre-forms are sintered or fused into a solid mass by heating them to a high temperature in a vacuum or hydrogen atmosphere furnace.

Some tungsten carbide ball sizes are Hot Isocratic Pressed or hipped. The newest procedure is to Sinter-HIP the parts in a single operation. Using micro size diamond dust, they are then finished lapped and polished to final size and microinch roundness with a sub-microinch surface finish.


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Making spectrographic chemical analysis of tungsten carbide ball can be difficult and uncertain,  so the accepted procedure is to use a magnetic permascopic evaluation.

The same exactness of chemistry and physical properties in tungsten carbide ball that are experienced with alloy metals cannot be expected, as T.C. is made from a physical mixture of a pure metal powder and a powdered ceramic. There will naturally be more variability in performance.


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Tungsten Carbide is neither a metal nor is it a ceramic. It is a cermetal although this isn't a widely used term. This is a combination of a large percentage of Tungsten Carbide ceramic particles bonded together by a small percentage of a metallic binder, to form a solid mass.

Tungsten Carbide is extremely stiff, with a Young's modulus of elasticity of 98,000,000 pounds per square inch, compared with steel at 30,000,000 PSI. This high stiffness makes cemented tungsten carbide balls a good choice for ball-sizing and they provide premier results as components of kinematic couplings.


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