Abrasion is the process of scuffing, scratching, wearing down, marring, or rubbing away. It can be intentionally imposed in a controlled process using an abrasive. Abrasion can be an undesirable effect of exposure to normal use or exposure to the elements.
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Ancient artists,[ when? ] working in stone, used abrasion to create sculptures. The artist selected dense stones like carbonite and emery and rubbed them consistently against comparatively softer stones like limestone and granite. The artist used different sizes and shapes of abrasives, or turned them in various ways as they rubbed, to create effects on the softer stone's surface. Water was continuously poured over the surface to carry away particles. Abrasive technique in stone shaping was a long, tedious process that, with patience, resulted in eternal works of art in stone.
The Archard equation is a simple model used to describe sliding wear and is based on the theory of asperity contact. [1]
where:
K is obtained from experimental results and depends on several parameters. Among them are surface quality, chemical affinity between the material of two surfaces, surface hardness process, heat transfer between two surfaces and others.
The resistance of materials and structures to abrasion can be measured by a variety of test methods. [2] These often use a specified abrasive or other controlled means of abrasion. Under the conditions of the test, the results can be reported or can be compared items subjected to similar tests.
Such standardized measurements can produce two quantities: abrasion rate and normalized abrasion rate (also called abrasion resistance index). The former is the amount of mass lost per 1000 cycles of abrasion. The latter is the ratio of former with the known abrasion rate for some specific reference material. [3]
One type of instrument used to get the abrasion rate and normalized abrasion rate is the abrasion scrub tester, which is made up of a mechanical arm, liquid pump, and programmable electronics. The machine draws the mechanical arm with attached brush (or sandpaper, sponge, etc.) over the surface of the material that is being tested. The operator sets a pre-programmed number of passes for a repeatable and controlled result. The liquid pump can provide detergent or other liquids to the mechanical arm during testing to simulate washing and other normal uses. [4]
Another example is the ASTM G65 test using dry sand with a rubber wheel for abrasion testing. This widely used test can evaluate coatings and materials for comparison of their resistance. G65 is often used for The ASTM G65 standard – “Standard Test Method for Measuring Abrasion Using the Dry Sand/Rubber Wheel Apparatus” – is one of the most widely used laboratory procedures for evaluating the abrasion resistance of metallic materials and coatings. In this test, a rubber wheel is rotated against a flat specimen while a controlled flow of silica sand is introduced between the wheel and the test surface, producing a three-body abrasion condition that simulates sliding wear in service.
Material volume loss is determined by weight loss and reported as a wear rate (typically in mm³ or mm³/kg of abrasive). Test parameters such as wheel load, abrasive feed rate, and rubber hardness are defined in five test procedures (A–E) within ASTM G65. [5] The method is particularly useful for ranking steels, weld overlays, and wear-resistant coatings used in mining, drilling, and agricultural equipment.
Similar abrasion tests include the ASTM G105 “Wet Sand/Rubber Wheel” method and the Taber abrasion test used for polymeric and coated surfaces.
The use of proper lubricants can help control abrasion in some instances. Some items can be covered with an abrasion-resistant material. Controlling the cause of abrasion is sometimes an option.
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