Measurement of Hardness, Wear Index and Abrasion Resistance of Anodic Coatings on Aluminium

Abstract

SummaryThe paper describes briefly the methods used in the measurement of hardness and wear resistance of anodic coatings on aluminium. Microhardness was the only test adopted in BS 5999 for hard anodic coatings. Resistance to wear is an important property but difficult to measure. The Taber test is discussed and also the more recent abrasive wheel tests and the older abrasive jet tests. Results are given showing the effects of temperature and anodizing current density on wear by jet tests and abrasive wheel tests and a comparison of the methods is made. Definitions of wear index and abrasion resistance are given and results are shown to depend on what information is selected in calculating them. The in-depth information from abrasive wheel tests is likely to have an impact on anodizing practice and to ensure greater freedom from surface erosion.