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2. ENGINEERING AND TECHNOLOGY
Tribological tests, mathematical modelling and simulations have been conducted over the last few decades to investigate the nature and effects of mechanical wear in coated and uncoated materials. Mathematical models have been developed and in unison with specifically designed empirical tests, the veracity/capability of these models has been investigated. In more recent cases advanced engineering analysis tools, such as FEA and DOE, are used to further compliment and refine experimental techniques.
Studies have focused on the various wear mechanisms: abrasion, adhesion, erosion, corrosion wear, fatigue wear and also on different combinations of these. The intrinsic importance of the material in these studies has lead to a wide range of coated and uncoated materials being used in experimentation and modelling. From analysis, some models are based wholly on established/ classical wear theory while more recent work on wear models have been based on micro and nano scaled scientific approaches.
In practical wear tests, some mathematical models assume certain wear profiles and symmetry for calculating wear volume or mass loss. These assumptions do not account for the very irregular patterns that are the result of most wear mechanisms. Modern instrumentation on the other hand can capture precise profiles and dimensions to produce a more accurate measurement of material loss.
Some authors also use certain parameters such as hardness, fatigue or tensile strength to represent the resistance of a material to wear. Hardness does give an indication of the wear resistance of a material; however studies have demonstrated that the addition of certain alloying elements increases the wear resistance but not the hardness. Therefore hardness alone cannot describe the wear resistance properties of a material.
The objective of this work was to examine a number of models that have been used for analysing wear of materials. It highlights some key details and techniques used by authors to ascertain wear rates and gives examples of modern approaches to wear measurement for coated engineering samples. Figures 1 to 5 show examples of wear on materials and components that are difficult to measure and model in terms of material loss due to their irregular shapes.
Montgomery, S., Kennedy, D., O'Dowd, N.:Analysis of Wear Models for Advanced Coated Materials. Matrib: International Conference on Materials, Tribology, Recycling, Lipanj, Croatia, June 24-26, 2009.