British Standards abrasion tests

The hardness and abrasion resistance of anodic coatings have never been easy properties to measure, but the development of a British Standard on hard anodising has made this essential. Film hardness is best measured by making microhardness indents on a cross-section of a film , but a minimum film thickness of 25 tm is required. For abrasion resistance measurements, a test based on a loaded abrasive wheel , which moves backwards and forwards over the film surface, has improved the sensitivity of such measurements. 

The surface hardness, as measured in a standard test, is an indication of a material s ability to resist wear. Hardness testing is covered by British Standards BS 240, 4175, 427 and 860. This will be an important property if the equipment is being designed to handle abrasive solids, or liquids containing suspended solids which are likely to cause erosion. 

The best way of assessing abrasiveness is to use the actual bulk material and the contact surfaces in question. One such test was developed by Yancey, Greer and Price61 and has been adopted in a British Standard for coke and coal62. From the test, another abrasiveness index is determined by measuring the wear on a standard surface when the surface is brought into moving and intimate contact with the coal under specified conditions. 

British Standard BS 1016, Methods for the analysis and testing of coal and coke, Part 19 1980 Determination of the index of abrasion of coal. 

The details of procedure and expression of results are something of a compromise, being a compilation of the German approach and the British approach. Two procedures are specified, using a rotating or non-rotating test piece respectively. In principle, the abrasion should be more uniform if the test piece is rotated during test. The standard abradant is specified in terms... 

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