The Hardness of Tungsten Carbide

WC is present in hardmetal in the form of single crystals. These have a hexagonal structure and are highly anisotropic [4], Table 1 lists the Vickers hardness of three WC crystal faces and shows that the hardness can vary from face to face by up to 100% [5]. On account of the superior hardness of the (0001) faces, attempts have been made to produce WC-Co parts with a (0001) texture [6], 

The literature contains contradictory results on the hardness of WC because it has been measured mostly on sections of hardmetal samples, where the grains are randomly oriented, rather than on single crystals. 

From Fig. 3 it has been calculated that //wc = 1330kgfmm and /sTowc = 24kgfmm /. It must be noted that the results reported in Fig. 3 were obtained at room temperature, thus the values of //qwc are expected to be those 

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The use of tungsten carbide alloyed with cobalt, well known as Hard Metal is used for cutting tools because of its excellent wear resistance but finds little use as a corrosion resistant material. 

What is the enthalpy of reaction, AH, for the formation of tungsten carbide, WC, from the elements (Tungsten carbide is very hard and is used to make cutting tools and rock drills.)... 

The hardness of carbides can only be deterrnined by micro methods because of britdeness, the usual macro tests caimot be used. Neither can the extremely high melting points of the carbides be readily deterrnined by the usual methods. In the so-called Priani hole method, a small hoUow rod is placed between two electrodes and heated by direct current until a Hquid drop appears in the cavity. The temperature is determined pyrometricaHy. When high temperature tungsten tube furnaces are used, the melting point can readily be estimated by the Seger-type cone method. The sample may also be fused in a KroU arc furnace and the solidification temperature determined. 

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