Standard Test for Knoop Indentation Hardness of Glass ASTM C730

Standard Test for Knoop Indentation Hardness of Glass ASTM C730

ASTM C730 is used to determine the Knoop indentation hardness of glass and to verify the Knoop hardness testing machine by using standard glasses. The Knoop indentation hardness test can be used to test a wide variety of glasses, from television faceplates to polished plate glass. The values are stated in SI units.

    Scope:

    In ASTM C730, the Knoop Indentation Hardness Test is used to determine the Knoop Indentation Hardness of glass. It determines the mechanical hardness of very brittle materials or thin sheets, where only a small indentation may be made for testing purposes. The test is valid for a wide range of test forces and very few samples are required. 

    Test Procedure:

    A pyramidal diamond point is pressed into the polished surface of the test sample with a known load, usually 100g, for a specified dwell time, and the dimension of the resulting indentation is measured using a microscope.

    The indenter leaves a tiny four-sided impression of about 0.01 to 0.1 mm in size. The length of the impression is approximately seven times the width, and the depth is 1/30 the length. Hence, after measuring only the length of the longest side, the area of the indentation can be calculated. The area of the indentation and the weight of the load are then used to calculate Knoop Indentation Hardness.

    The Knoop indentation hardness test can be used to test a wide variety of glasses, from television faceplates to polished plate glass. In general, the accuracy of the test will depend on the smoothness of the surface

     Specimen size:

    The surface of the sample should be smooth and polished. The sample should be over ten times as thick as the indentation depth but not so thick as to affect the hardness of the glass. In general, if specimens are at least 0.10 mm thick, the hardness will not be affected by variations in the thickness. 

    Data:

    Knoop Indentation Hardness (HK) is calculated by

    HK = 14.229(F/D2)

    Where,
    F = the applied load
    D2 = the area of the indentation

    The Knoop hardness number (KHN) is calculated by:

    KHN = (P/A)
    Where,
    P = load
    A = projected area of the indentation

    OUR SERVICES

    Core Materials Testing Services

    Metrology

    A variety of microscopy and spectroscopy tools available for precise measurements from the nano to the meter scale.

    Metrology Testing Services

    POPULAR TESTS:

    TEM SIMS Profilometry

    Materials Testing

    ASTM and ISO standard and custom chemical, mechanical, thermal, corrosion tests, etc. for all materials metals, ceramic or polymers.

    Materials Testing Services

    POPULAR TESTS:

    Nondestructive Testing Electrical Testing Chemistry Analysis

    Product Testing

    Thousands of tests for product quality and reliability under heat, humidity, temperature shock, vibration, drop, electrostatic discharge.

    Product Testing Services

    POPULAR TESTS:

    Vibration Testing Humidity Testing Accelerated Aging

    Looking for Material Testing?

    We have 500+ Material Test already Done for top companies

      Send us a request