ASTM C730 Knoop Indentation Hardness of Glass

Scope:

ASTM C730 has been made to compare Knoop indentation hardness with tensile strength, grinding speeds, and other hardness scales. Knoop hardness is one of many properties that is used for the characterization of glass.

Test Procedure:

In ASTM C730, the Knoop Indentation Hardness of Glass is an imprint of the undeformed indentation. An Indentation hardness test is done by using a calibrated machine to force a rhombic based, pointed, pyramidal diamond indenter having specific face angles, under a fixed load, into the surface of the material under test. The long diagonal of the resulting impression after removing the load is measured.

Specimen Size : 

For ASTM C730, the specimen should remain intact with an indenter between the 20s and 30s. The rate of indenter motion with specimen should be 0.20 ± 0.05 mm/min and the test load should be 100gf.

Data:

The  Knoop hardness HK for ASTM C730 is calculated by using the following equation

Conclusion:

ASTM C730 is a microhardness test described to determine the Knoop indentation hardness of glass.