Cemented carbide

Cemented carbide is a hard material used extensively in cutting tools for machining, as well as other industrial applications. It consists of fine particles of carbide cemented into a composite by a binder metal. Cemented carbides commonly use tungsten carbide (WC), titanium carbide (TiC), or tantalum carbide (TaC) as the aggregate. Mentions of "carbide" or "tungsten carbide" in industrial contexts usually refer to these cemented composites.

Most of the time, carbide cutters will leave a better surface finish on the part, and allow faster machining than high-speed steel or other tool steels. Carbide tools can withstand higher temperatures at the cutter-workpiece interface than standard high-speed steel tools (which is a principal reason for the faster machining). Carbide is usually superior for the cutting of tough materials such as carbon steel or stainless steel, as well as in situations where other cutting tools would wear away faster, such as high-quantity production runs.

Cemented carbides are metal matrix composites where carbide particles act as the aggregate and a metallic binder serves as the matrix (like gravel aggregate in a matrix of cement makes concrete). Its structure is thus conceptually similar to that of a grinding wheel, except that the abrasive particles are much smaller; macroscopically, the material of a carbide cutter looks homogeneous.

The process of combining the carbide particles with the binder is referred to as sintering or hot isostatic pressing (HIP). During this process the binder eventually will be entering the liquid stage and carbide grains (much higher melting point) remain in the solid stage. As a result of this process the binder is embedding/cementing the carbide grains and thereby creates the metal matrix composite with its distinct material properties. The naturally ductile metal binder serves to offset the characteristic brittle behavior of the carbide ceramic, thus raising its toughness and durability. By controlling various parameters, including grain size, cobalt content, dotation (e.g., alloy carbides) and carbon content, a carbide manufacturer can tailor the carbide's performance to specific applications.

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