Characteristics and Applications of WC-Co Cemented Carbides

摘要

In a broad sense, cemented carbides is the common name of materials produced by sintering metals (Fe: iron, Co: cobalt, and Ni: nickel) and carbides of metals belonging to IV-VI groups of the periodic table of elements. Among the metals, Co shows a good wetting ability for tungsten carbide (WC) and allows us to easily obtain compacts, and since mechanical properties of such compacts are much higher than those of other combinations, therefore, sinters of WC-Co are used most widely. Additionally, by the above definition, TiC-Ni (TiC: titanium carbide) alloys belong to cemented carbides, but from a practical point of view, a WC-Co alloy is classified as a cemented carbide, and TiC-Ni alloy is classified as a cermet. Cemented carbide contains carbide particles (WC) and a ductile metal-binding phase (Co), and Young's modulus and the hardness of cemented carbide can be controlled in a wide range by varying the ratio of the binding phase in a composition. High-temperature properties and corrosion resistance of cemented carbide can be improved by adding carbides of different metals in microscopic amounts. The external view of components (dies) made of cemented carbide is shown in Fig. 1. Such cemented carbide materials are generally harder than metal materials and show toughness much better that that of ceramic materials. Therefore, cemented carbides are used in a wide range of applications combined with severe friction conditions, such as fixtures in which properties as the wear resistance are required, as a cutting edge of different cutting and excavation tools, dies for pressing processes, and so on.