ISO 8251-2011 pdf free download.Anodizing of aluminium and its alloys — Measurement of abrasion resistance of anodic oxidation coatings.
4 Characteristics of abrasion tests
There are three kinds of abrasion tests: abrasive-wheel-wear test, abrasive jet test and falling sand abrasion test.
4.1 Abrasive-wheel-wear test Determination of the resistance to abrasion by movement of a test specimen relative to an abrasive paper under a specified pressure. The wear resistance or the wear index of the layers of oxide near the surface, or of the whole oxidation coating thickness, or of any selected intermediate zone may be determined by the method described. For most purposes the wear index (see 5.4.3) or the mass wear index (see 5.4.4) will be the most appropriate characteristic to determine. The method is applicable to all anodic oxidation coatings of thickness more than 5 μm on flat aluminium or its alloy specimens. This method is not applicable to concave or convex specimens; these may be examined using the abrasive jet test method which will give an average value for the abrasive resistance of the coating (see 4.2 and Clause 6). NOTE Minimum test specimen dimensions of 50 mm × 50 mm are normally required.
4.2 Abrasive jet test Determination of the resistance to abrasion by the impact of abrasive particles projected onto a test specimen. The mean specific abrasion resistance of anodic oxidation coatings may be determined. NOTE 1 Different batches of the same abrasive are liable to give different results and for this reason the test is a comparative one. NOTE 2 With a suitably designed abrasive jet and film-thickness-measuring devices with a small probe, it is possible to conduct a depth survey which indicates how abrasion resistance varies through the coating thickness (see Annex B). However, this property is preferably measured using the abrasive-wheel-wear test. The method described is applicable to all anodic oxidation coatings of thickness more than 5 μm on aluminium or its alloys. It is primarily intended for surfaces which are not flat.
If suitable flat test surfaces are available, the abrasive-wheel-wear test is the preferred method. Production components may be tested without cutting if the apparatus chamber can accommodate these. NOTE 3 This method is particularly suitable for small test specimens because the individual test area required is only about 2 mm in diameter. 4.3 Falling sand abrasion test Determination of the resistance to abrasion by the impact of freely falling abrasive particles onto anodic oxidation coatings. The method described is applicable to the thin anodic oxidation coatings.ISO 8251 pdf download.