Cemented carbides represent a group of materials which differ from other hard materials such as ceramics, corundum or diamond in view of their metallic properties.
These metallic properties include for example good electrical and thermal conductivity.
Carbide is a powder-metallurgical two-phase material consisting of a hard material phase and a metal binder phase. The hard material provides the necessary hardness (= wear resistance) and the binder metal guarantees appropriate toughness.
In the case of cemented carbides for cutting tools and wear protection, tungsten carbide (WC) is generally used as a hard carbide phase and cobalt (Co) as metal binder (binder phase). The reason for this is that applying this combination the best physical and mechanical properties can be obtained.
The most important parameters for determination of the carbide properties are the binder content (generally stated as a mass fraction) and the average grain size of the hard material phase.
Properties of cemented carbide relevant for the application:
- Wear resistance/hardness
- Compressive strength
- Impact strength
- Transverse rupture strength
- Tribological properties
- Specific weight
- Magnetic properties
- Young’s modulus (modulus of elasticity)/rigidity
- Thermal properties
- Corrosion resistance, resistance to oxidation
In view of the manifold possible combinations of the metal binder content and the grain size, cemented carbide covers a wide range of applications, as can be seen in the following chart.
Advantages of cemented carbide:
- does not wear so quickly as it is harder
- resists even high temperatures
- application fields: wherever tools or components are exposed to high wear (e.g. when cutting hard materials)
- improved quality of the tools and parts
- longer tool life
- improved security
Cemented carbide in comparison to other materials:
- Diamond/PCD: hardest existing material, but characterised by high fracture toughness
- Cemented carbide: enormous flexibility thanks to composition, can be designed either with higher toughness or higher wear resistance depending on the application. Range of applications varies extremely for cemented carbide and offers the greatest scope
- Steel: high toughness, but low hardness
- Ceramic: very low density, lighter than cemented carbide and heat-conducting, excellent hardness, low toughness
- CBN: high hardness, low toughness
- Cermet: high hardness, combines the hardness of cemented carbide and ceramic, but less tough