ASTM C1327 Vickers indentation hardness of ceramics

Scope:

ASTM C1327 test method explains the measurement of Vickers indentation hardness of advanced ceramics. This test is easier when compared with other hardness tests as it is independent of the size of the indenter. This test is specifically used for small parts, thin sheets or case depth work, where a small square-shaped indentation is made for testing purposes. The average diagonal size of the square-shaped indentation and the applied force are used for calculating the Vickers hardness. Keeping the applied load the same, the Vickers test procedure in ASTM C1327 produces 1.5 times deeper indentation than the Knoop indentation method.

Test Procedure:

In the test ASTM C1327, the ratio of the force applied to the contact surface area determines the hardness of the test ceramic specimen. By varying the range of the predetermined applied loads, full characterization curve of Vickers hardness can be obtained in terms of Vickers hardness number (HV). The HV number in ASTM C1327 is determined by the ratio F/A, where F is the force or the load applied in kilograms-force and A is the polished surface of the specimen on which indentation is being done in square millimeters. These units are further converted into SI systems of units.

Sample size:

The test specimen in ASTM C1327 must be highly polished which enables measuring the size of the impressions by the square-based, pyramidal diamond shaped indent.

Data:

The units of hardness given by the test in ASTM C1327 follows a Vickers Pyramid Number (HV) or Diamond Pyramid Hardness (DPH). These numbers can be converted into the units of Pascals, however, they are not to be confused with pressure i.e. measuring area normal to the force, but instead these are determined by the load over the surface area of the indentation. The values in SI units are to be considered as standard.

Conclusion:

The ASTM C1327 test is a microhardness test that uses a pointed, pyramidal diamond shaped, square-based indent, pressed into the surface of the test ceramic specimen with a known load, thus producing a relatively small permanent indentation which can be further measured using a light microscope.