ISO 6370-2:2020 pdf download – Vitreous and porcelain enamels — Determination of the resistance to abrasion — Part 2: Loss in mass after sub-surface abrasion.
7 Test specimens 7.1 Prepare the test specimens in accordance with the International Standards for the appropriate basis metal. Specimens for testing vitreous and porcelain enamels for sheet steel and cast iron shall be prepared in accordance with ISO 28764. 7.2 Rinse each test specimen and reference glass plate with water (5.2) and wipe it thoroughly with ethanol (5.1). Dry the test specimens and the reference glass plates in the drying oven (6.4) for 2 h at 120 °C ± 5 °C. Remove them from the oven and allow them to stand for at least 2 h in the desiccators (6.5) and weigh each specimen to the nearest 0,2 mg (initial mass). 8 Procedure 8.1 Carry out one test with each set of at least three test specimens and three reference glass plates. 8.2 Fix the test specimens and the reference glass plates on the oscillating table of the abrasion testing apparatus (6.1) with the aid of the retaining rings, sealing rings and clamping devices, so that the cover coat sides of the test specimens and the float-bath surface (see Annex A) of the reference glass plates are facing the interior of the retaining rings (see ISO 6370-1:1991, Figure 1). 8.3 Fill each retaining ring with an abrading charge and close it with the stopper. The abrading charge consists of the following: — 80 g of steel balls (5.3) that are 4 mm in diameter; — 60 g of steel balls (5.3) that are 3 mm in diameter; — 35 g of steel balls (5.3) that are 2 mm in diameter; — 20 ml ± 0,2 ml of water (5.2); — 3 g + 0,01 g of abrasives (5.4). The limiting deviations in mass for the balls: mass of each single ball.
8.4 Start the oscillating table of the abrasion testing apparatus for a period of 30 min ± 1 min, corresponding to 9 000 rotations ± 300 rotations. Then, remove the specimens and reference glass plates, and thoroughly rinse the test specimens, the reference glass plates, the retaining rings and the sealing rings under running water. Dry the test specimens and reference glass plates in air and replace them on the abrasion testing apparatus with a fresh abrading charge (see 8.3). The steel balls may be used again after thorough cleaning. If the thickness of the enamel coat to be tested is less than 0,2 mm, it is recommended to weigh the test specimen before the next test period. Start the oscillating table for a further period of 30 min and then repeat the whole procedure a third time. If the vitreous and porcelain enamel coat being tested has already disappeared, interrupt the test.