Hard facts
Theory of hardness testing
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The Knoop method is a static hardness testing method, which was developed as an alternative to the Vickers method and is used in particular for the testing of thin layers and brittle materials. It can be characterised as follows:
- It is one of the standardised procedures (ISO 4545, ASTM E92, ASTM E384).
- The Knoop method has a test load range of 1 gf to 2 kgf according to ISO and ASTM, which means that this method can be used for hardness testing in the micro and low-load ranges.
- It is an optical method. This means that the size of indentation left by the indenter is measured to determine the hardness value of a test specimen.
- Indenter shape and material: The indenter consists of a pyramid-shaped diamond with a rhomboid base, with a longitudinal edge angle of 172.5° and a transverse edge angle of 130°.
