Wear resistance
The most important characteristic of cemented carbide is its wear resistance. This combination of properties is related to surface phenomena. When two surfaces slide against each other, material will be removed from both of them. At a low load, this loss of material will take place through the loss of single grains or parts of single grains. This process is generally referred to as attrition. At higher load, the loss of material takes place by clusters of grains becoming detached. This process is known as abrasion. Both these processes, leading to loss of surface material, contribute to wear. In practice, the material loss is often also affected by the local environment, particularly if corrosion or oxidation is encountered. The nature of wear is very complex, and the wear rate depends on many variables. However, evaluations of wear resistant materials can be done in the laboratory under standardized conditions. Such evaluations of wear resistance indicate the ranking between the tested wear resistant materials under these specified conditions only.
In a test of wear resistant material based on ASTM B611-85, the test sample is pressed against the periphery of a rotating disc, partly immersed in a slurry of alumina (Al2O3) particles in water. The abrasive wear resistance is influenced by the cobalt content and the tungsten carbide grain size as shown in the diagrams.
