BS 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
5 Reagents and materials
For cleaning the test specimens and the reference glass plates, use the following reagents (5.1 and 5.2).
5.1 Ethanol (C 2 H 5 OH), with a volume fraction between 96 % and 98 %.
5.2 Distilled water, or water of equivalent purity (grade 3 water in accordance with ISO 3696).
5.3 Steel balls.
For each test on a set of three specimens and three reference glass plates, use the following (see 8.3):
— 480 g of balls that are 4 mm in diameter;
— 360 g of balls that are 3 mm in diameter;
— 210 g of balls that are 2 mm in diameter.
Balls shall consist of the same stainless steel of the type used for bearings and shall be hardened, for example, type of steel 20 in accordance with ISO 683-17.
5.4 Abrasives, as follows.
— Grains of milled sanidine K(AlSi 3 O 8 ) (potassium feldspar), of grain size P 100, in accordance with ISO 6344-2. If a higher abrasion is required, fused alumimium oxide shall be used for the test.
NOTE Feldspar represents 60 % of earth’s crust, therefore, sanidine is an appropriate material to test resistance to abrasion in most cases.
— Grains of fused aluminium oxide, of grain size P 80, in accordance with ISO 6344-2.
6.1 Abrasion testing apparatus, in accordance with ISO 6370-1.
6.2 Balance, accurate to 0,2 mg.
6.3 Pipette, of nominal capacity 25 ml, at least class B, in accordance with ISO 648.
6.4 Drying oven, capable of maintaining temperatures of at least 130 °C.
6.5 Desiccator, with an internal diameter of 200 mm.
6.6 Reference glass plates, square plates with a side length of 100 mm and thickness of 3 mm, consisting of float glass. For each test, a set of three reference glass plates is required. For identification of the float-bath surface of the glass plates, see Annex A.
NOTE Float glass is made by a process in which a ribbon of hot glass is floated upon a heated liquid of density greater than that of the glass.
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).
8.1 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.BS ISO 6370-2 pdf download.