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ISO 8251-2011 pdf free download
ISO 8251-2011 pdf free download.Anodizing of aluminium and its alloys — Measurement of abrasion resistance of anodic oxidation coatings
Anodisation do I’aluminium of de sos alliages — Determination de Ia résistance a I’abrasion des couches d’oxyde anodiques.
The anodic oxidation coatings on a test specimen are abraded, under defined conditions, by reciprocal motion against a strip of silicon carbide paper attached to the outer circumference of a wheel. After each double stroke, the wheel turns through a small angle to bring an unused portion of the abrasive strip into contact with the test area. The decrease in coating thickness or mass obtained is used to calculate the wear resistance or wear index. This result is compared with that obtained using a standard specimen (see Annex A) or reference specimen (see 3.3).
The method normally requires an eddy-current meter with a probe of less than 12 mm diameter. If this is not available, the method of loss in mass should be used.
NOTE A complete presentation of the wear ctiaractenstics of the anodic oxidation coatings can be obtained by progressively abrading the test area, until the substrate metal is revealed, and then constructing a graph to show the relation between (he coating thickness removed and the number of double strokes used. This is referred to as a depth survey of the anodic oxidation coatings (see Annex B).
The testing environment should be at room temperature and the relative humidity should be under 65 %.
5.2.1 Abrasive-wheel-wear test apparatus
The apparatus consists of a clamping device or pressure plate for holding the test specimen (see 5.3.2) level and rigid, and a 50 mm diameter wheel to the outer circumference of which is attached a 12 mm wide strip of silicon carbide paper (see 5.2.2). The force between the wheel and the test surface shall be capable of being varied from zero to at least 4,9 N with an accuracy of ±0,05 N. The abrasive action is produced either by the fixed wheel sliding to and fro in a horizontal plane In parallel contact with the test surface over a 30 mm length or. alternatively, by the test specimen sliding in a similar way over the stationary wheel. Typical apparatus is illustrated in Figure C.1.
After each double stroke, the wheel is advanced through a small angle to bring a fresh area of the silicon carbide paper into contact with the surface before making the next double stroke. The angle of rotation is such that, after 400 ds, the wheel will have made one complete revolution. At this stage, the strip of silicon carbide paper shall be renewed. The relative speed of movement shall be (40 ± 2) ds per minute. The number of double strokes can be registered by means of a counter, and provision is normally made for the apparatus to switch off automatically after a preset number of double strokes has been reached (400 ds maximum). The test surface shall be kept free from loose powder or abrasion detritus during the test.
5.2.2 AbrasIve strip
The abrasive strip consists of P320 silicon carbide paper (in accordance with ISO 6344-1) 12mm wide. Its length shall be such that it covers the abrasive wheel without overlapping, and it shall be either bonded or mechanically clamped into position.
NOTE P320 paper is 45 ijm grade (320 mesh).ISO 8251-2011 pdf free download.
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