GB/T 23988-2009Determination for abrasion resistance of - Coatings by falling abrasive (English PDF)

1 Scope

This Standard specifies the determination method for abrasion resistance of single-layer or multi-layer coatings of paints, varnishes or related products.

This test method is applicable to the determination for abrasion resistance of single-layer or multi-layer coatings of paints, varnishes or related products by dropping abrasive materials on the coating. The abrasion resistance is expressed as the amount of abrasive required to wear and tear a unit film thickness of the coating.

2 Normative references

The terms in the following documents become the terms of this Standard by reference to this Standard. For dated references, all subsequent amendments (not including errata content) or revisions do not apply to this standard. However, parties to agreements that are based on this Standard are encouraged to study whether the latest versions of these documents can be used. For undated references, the latest edition applies to this Standard.

GB/T 3186, Paints varnishes and raw materials for paints and varnishes - Sampling (GB/T 3186-2006, ISO 15528:2000, IDT)

GB/T 9271, Paints and varnishes standard panels for testing (GB/T 9271-2008, ISO 1514:2004, MOD)

GB/T 13452.2, Paints and varnishes - Determination of film thickness (GB/T 13452.2-2008, ISO 2808:2007, IDT)

GB/T 20777, Paints and varnishes - Examination and preparation of samples for testing (GB/T 20777-2006, ISO 1513:1992, IDT)

3 Instruments and materials

3.1 Wear tester, as shown in Figure 1, with a switch near the top of the conduit to control the flow of abrasive materials. It consists of a metal disc inserted into a narrow slit on one side of the conduit with a collar covering the slit of the conduit. Firmly hold the conduit in a vertical position on the top of a suitable container. There shall be a support on the equipment for placing the painted sample at an angle of 45° to the vertical

5 Sampling

Take representative samples of the product under test (or each product in a multi-coating system) in accordance with GB/T 3186.

Inspect and prepare test samples according to the provisions of GB/T 20777.

6 Test plate

7 Operation steps

7.1 Unless otherwise agreed, the tests shall be carried out at a temperature of (23 ± 2) °C and a relative humidity of (50 ± 5) %.

7.2 Mark a circular area with a diameter of approximately 25 mm on each test block and position each circular area appropriately on the abrasion test plate support. Measure the coating thickness according to the provisions in 6.4. At least 3 test points are required for each circular area. Record the average measured value of the coating thickness on each circular area.

7.3 Fix the coated test plate on the tester as described in 3.1. Adjust the test plate so that the marked circular area is just below the center of the conduit; pour a certain volume of standard sand into the funnel; turn on the switch; let the sand pass through the conduit and hit the coated test plate. The container installed at the bottom of the tester collects the fallen sand. Repeat the above operation until the coating is destroyed and the substrate of an area of 4 mm diameter is exposed. During the test, the appropriate incremental sand is 2 000 mL ± 20 mL. When approaching the end point, 200 mL ± 2 mL of sand can be added to the funnel.

Note 1: When the conduit is switched on, ensure that the collar covers the narrow slit of the conduit opening.

Note 2: In order to ensure that the center of the sand beam falls exactly in the center of the sand flow, check the centering of the conduit at regular intervals.

Note 3: The sand shall be replaced after passing through the instrument 25 times.

7.4 Repeat the tests of 7.1 ~ 7.3 on another test plate with the same coating.

8 Result calculation

Calculate the abrasion resistance of the test area of the coated test plate according to the following formula:

Where: A - abrasion resistance, in liters per micron (L/µm); V - volume of abrasive material used, in liters (L); T - coating thickness, in microns (µm).

Take the arithmetic mean of two parallel determinations as the result, with one decimal place retained. The difference between the two parallel determinations shall be less than 25% of their average value.

9 Test report

The test report shall at least include the following:

a) a reference to this Standard (GB/T 23988);

b) details required to identify the product and abrasive material being tested;

c) test results expressed in accordance with Clause 8; […]