Impact wear definition

Erosion is defined as the loss of hard tissue by chemical means not derived from bacteria, i.e. the dissolution of hard tissue by acid where the acid source is not the oral bacteria [5], Erosion may be caused by either intrinsic (e.g. stomach acid) or extrinsic (e.g. dietary) sources. Erosion is often associated with the consumption of acid products, such as fruits or acid beverages, or with medical conditions where reflux of acidic into the oral cavity is present. Interestingly, the term erosion is widely used in other fields where the definition is rather different. For example, in the field of tribology, erosion refers to the loss of material from a surface by solid or liquid impacts [6], In the classical tribological definitions, the mechanism dentists refer to as erosion would be described as corrosion, or tribo-chemical wear. 

ASTM G 40 ASTM G 73 Standard Terminology Relating to Wear and Erosion Standard Practice for Liquid Impingement Erosion Testing Definition of terms for erosion and wear. Resistance to erosion from impacts of liquid drops or jets. 

It is useful at this point to consider the definition of an additive as given by the EC (European Commission) an additive is a substance, which is incorporated into plastics to achieve a technical effect in the finished product, and is intended to be an essential part of the finished product. Since the very early stages of the development of the polymer industry, it was realized that useful materials could only be obtained if certain additives were incorporated into the polymer matrix, in a process normally known as compounding. Additives confer on plastics significant extensions of properties in one or more directions, such as general durability, stiffness and strength, impact resistance, thermal resistance, resistance to flexure and wear, acoustic isolation, etc [86]. 

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