Hardness / Scratch Resistance

Hardness / Scratch Resistance The property of a substance that is resistant to repeated rubbing or scratching. In general, it meant the resistance of a (coating) layer or surface against mechanical friction. Abrasion of products is a concept that can’t be handled in general. One must explicitly specify the conditions under which the product must be durable. Any change in ...

Hardness / Scratch Resistance

The property of a substance that is resistant to repeated rubbing or scratching. In general, it meant the resistance of a (coating) layer or surface against mechanical friction. Abrasion of products is a concept that can’t be handled in general. One must explicitly specify the conditions under which the product must be durable.

Any change in wear conditions, the assessment of the wear thoroughly change. In general we distinguish wear as single or repetitive. In the former case, a small contamination in the long run leads to serious damage. By repeating is meant the resistance of a surface under prolonged load. The lowering of the coefficient of friction can give a significant improvement. For the determination of the abrasion resistance it should be practical to approach conditions as much as possible.

Forms of wear or scratch resistance are e.g. brush abrasion testing, rotating abrasion testing, rub testing, sand fall testing and or shear tests.

Hardness

The determination of the reactive resistance, the hardness of a surface of which a coating or alternative protective layer is provided. As with abrasion and scratch resistance there should be an explicit reference given to the hardness meant. Under the hardness of the coatings is in general understood the impression value at which a deformation of the coating occurs. This is determined by pressing sharp or blunt stylus, depending on the material or coating, into the surface.

Another method to measure hardness is the determination of rolling resistance of a coated surface. The equipment required is using spheres that find resistance during the rolling movement on the test surface i.e. Pendulum hardness. The degree of hardness determines on the number of movements by a pendulum roller experiencing resistance during this process.

Other types of hardness tests are, Barcol Impression, Shore A-D, Sclerometer and Wolf-Wilburn pencil scratch resistance determination and Persoz or Konig pendulum hardness testers.


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