Cemented Carbides

Topics Covered

Background

Key Properties

Applications

Cutting Tools

Background

Cemented carbides are a family of metal matrix composites (MMC’s), of which the most common example is tungsten carbide (WC). In general they consist of hard ceramic particles in a metallic matrix.

The toughness of these ceramic materials is increased by combining with metals such as cobalt. Production involves mixing of powders of both materials, pressing, and heating to above the melting temperature of cobalt. The molten cobalt surrounds the ceramic particles and bonds the composite together forming a tough, impact resistant material.

Key Properties

•         High hardness

•         Excellent impact resistance

•         Good toughness

Applications

Cutting Tools

Due to their high hardness and excellent impact resistance, cemented carbides are most commonly used for cutting tools in lathes and similar industrial machines. They can be used to machine materials such as quenched and tempered steels. Due to their stiffness, they can be used to machine materials to high tolerances.

Although cemented carbides are harder than the materials that they are generally used to machine they do wear. However, when the ceramic particles at the cutting face become dull, they either fracture or pull out of the metal matrix to expose fresh, sharp particles.

The proportion of metal in the composite depends on the actual operation that the cutting tool is performing. For coarse machining, the metal content is higher to provide increased toughness, while for finish machining, the matrix content is kept lower so that particles can pull out easily, maintaining a sharp cutting face.

Primary author: AZoM.com