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Scratch hardness test or scratch test refers to any of a number of methods of measuring scratch hardness. Resistance to abrasion is less affected by surface variations than indentation methods. Scratch hardness is measured with a sclerometer. [1] Attempting to scratch a surface to test a material is a very old technique. [2]
The Turner-Sclerometer test consists of measuring the amount of load required to make a scratch. [1] [2] In test a weighted diamond point is drawn, once forward and once backward, over the smooth surface of the material to be tested. The hardness number is the weight in grams required to produce a standard scratch.
When testing coatings, scratch hardness refers to the force necessary to cut through the film to the substrate. The most common test is Mohs scale, which is used in mineralogy. One tool to make this measurement is the sclerometer. Another tool used to make these tests is the pocket hardness tester. This tool consists of a scale arm with ...
A scratch is defined as a long and narrow defect that tears the surface of the glass or coating. [6] There are standards that refer to the degree of visibility, which is the relative brightness of the scratch. In these cases, there is also a standard for the lighting conditions used for the test.
Mohs hardness kit, containing one specimen of each mineral on the ten-point hardness scale. The Mohs scale (/ m oʊ z / MOHZ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of minerals through the ability of harder material to scratch softer material.
ASTM G105 Standard Test Method for Conducting Wet Sand/Rubber Wheel Abrasion Tests [21] ASTM G132 Standard Test Method for Pin Abrasion Testing [22] ASTM G171 Standard Test Method for Scratch Hardness of Materials Using a Diamond Stylus [23] ASTM G174 Standard Test Method for Measuring Abrasion Resistance of Materials by Abrasive Loop Contact [24]
A Scratch test may refer to: The skin allergy test used in the medical diagnosis of allergies; Scratch hardness tests, such as Mohs scale of mineral hardness, used to measure the scratch resistance of various minerals; Liver scratch test, used by medical professionals to ascertain the location and size of a patient's liver during a physical ...
Scratch tests at low loads, such as the Bierbaum microcharacter test, performed with either 3 gf or 9 gf loads, preceded the development of microhardness testers using traditional indenters. In 1925, Smith and Sandland of the UK developed an indentation test that employed a square-based pyramidal indenter made from diamond. [11]