Abrasive Materials: Their Composition And Properties
One of the most important properties necessary in an abrasive material is hardness. Simply put, the abrasive must be harder than the material it is to grind, polish, or remove. Hardness of the various abrasive materials can be measured on a number of scales, including the Mohs hardness test, the Knoop hardness test.
The table lists prominent natural and synthetic abrasive materials. Links are provided from the table to further information on the materials and the hardness scales.
Hardness of prominent abrasive materials | ||||
abrasive materials | hardness | |||
Mohs scale | Knoop scale | |||
synthetic abrasive grain | synthetic diamond | 10 | 8,000–10,000 | |
boron carbide | 9–10 | 2,200–5,100 | ||
silicon carbide | 9 | 2,000–3,700 | ||
fused alumina | 9 | 2,000–2,600 | ||
Toughness or body strength characteristics are also significant to abrasive function. In synthetic abrasives it is possible to achieve some degree of control over this property by varying grain shape during the crushing or sizing operation, by making changes in the purity of the abrasive, by alloying abrasives, and by controlling the crystal structure within abrasive grains. Thus abrasives can be developed to meet the variety of applications.