GB/T 9966.4-2020Test methods for natural stone—Part 4:Determination of abrasion resistance (English PDF)

3.1 Instruments and Equipment

3.1.1 Abrasion testing machine

The grinding disc type abrasion testing machine, as shown in Figure 1, mainly consists of a rotating sample holder for holding the sample, a rotating steel grinding disc, and abrasive. It consists of an application device and other supporting components. The sample holder drives the sample to rotate, and wear is generated between the abrasive and the rotating grinding disc, from which the sample is worn. The wear resistance of the test specimens is then evaluated. The steel grinding disc has a hardness of 203 HB to 245 HB, a diameter of 254 mm ± 1 mm, and a rotation speed of 45 r/min ± 1 r/min; the four sample clamps are uniform. Distributed on a 180 mm diameter circle concentric with the grinding disc, the sample clamp rotates at a speed of 45 r/min ± 1 r/min; sample clamp, vertical shaft, and rotary... The total weight of the sample rotating gear and load adjustment device was 2000 g, which was applied to the sample; during the test, the abrasive application device was used at a rate of 60g/min. Abrasive is added at a constant speed of 70 g/min; the vertical axis can move freely up and down in the vertical direction.

3.1.2 Balance

The measuring range is 1000 g, and the accuracy is 0.01 g.

3.1.3 Forced-air drying oven

The temperature can be controlled within the range of 65°C ± 5°C.

3.2 Test Samples

3.2.1 Select representative stone samples, and the test surface should be mirror-like or smooth.

3.2.2 The length and width of the specimens are both 50 mm ± 0.5 mm, and the thickness is 15 mm to 50 mm. Each group consists of 4 specimens, with 4 test surfaces.

3.3 Test Procedure

3.3.1 The sample was dried in a forced-air drying oven at 65°C ± 5°C for 48 hours, then cooled to room temperature in a desiccator, and finally weighed. (mo), accurate to 0.01g.

3.3.2 White corundum with a particle size of 0.25 mm conforming to GB/T 2479 is used as the abrasive, and the moisture content of the abrasive is less than 1%. Four... The specimen is fixed in the specimen holder. Before the test, a layer of abrasive material should be evenly sprinkled on the grinding disc and placed between the specimen and the grinding disc. Then, the abrasion resistance test is started. The machine grinded the sample continuously on the grinding disc for 225 revolutions, then stopped. The sample was removed, cleaned of dust, and weighed (m1), accurate to 0.01g. Test It should be carried out at a relative humidity of 30% to 40%.

3.3.3 Place the sample in water for 1 hour, remove it, wipe the surface dry with a damp cloth, weigh it (m2), and weigh its mass in water (m3). GB/T 9966.3 Calculate the bulk density (p) of the sample.

3.4 Test Results

4.1 Instruments and Equipment

4.1.1 Wide-wheel wear-resistant machine

Figure 2 shows a schematic diagram of the wear-resistant equipment. It mainly consists of a steel rotating grinding wheel, a sample holder, and a constant-mass balancing device to move the sample. It consists of a clamping carriage that pushes the grinding wheel, an abrasive application device, a rotation speed measuring device, and other supporting components. A constant pressure is applied to the sample, through... The abrasive is ground into grooves of varying depths by the end face of the rotating grinding wheel, thereby evaluating the wear resistance of the sample. The grinding wheel has a hardness of 203 HB to 245 HB, a diameter of 200 mm ± 1 mm, an edge thickness of 70 mm ± 1 mm, and a rotation speed of 75 revolutions per minute. 60 s ± 3 s. The fixture carriage can push the sample horizontally toward the grinding wheel using a constant mass balancer, the mass of which is 14 kg ± 0.01 kg. The abrasive application device consists of a storage hopper with a control valve and a flow control hopper for adjusting the abrasive flow rate. The storage hopper is used for... The abrasive switch controls the supply of abrasive to the flow control hopper. The flow control hopper, which maintains a constant flow rate of abrasive, can be cylindrical or square and should have [specific features]. A slit exit. The slit is 70 mm ± 1 mm long and 4 mm ± 1 mm wide. The length of the exit should not be less than the actual thickness of the grinding disc. Degree. When the flow control bucket is cylindrical, the slit distance from the inner wall of the flow control bucket in all directions shall not be less than 10 mm; when the flow control bucket When the shape is square, the position of the slit is unrestricted, but at least one side is diagonally proportional to the length of the slit. The drop distance between the slit and the grinding wheel shaft is 100 mm ± 5 mm, and the abrasive drop point is 1 mm to 5 mm inward from the edge of the grinding wheel. The abrasive should flow evenly through the slit to the grinding wheel at a flow rate of 4.0 L/min ± 0.1 L/min. The abrasive flow rate should be kept stable, and the flow rate should be controlled within the hopper. The minimum height of the abrasive is 25mm. The sample on the fixture carriage should be perpendicular to the grinding wheel, and the fixture carriage and flow control slit should be parallel to the grinding wheel axis. The fixture carriage and balance weight should be aligned. There should be no improper friction, and an abrasive collector should be installed under the grinding wheel.

4.1.2 Magnifying glass

The magnification is at least 2x, and it is equipped with corresponding lighting equipment.

4.1.3 Steel ruler

Measuring range 100 mm, minimum graduation 0.5 mm.

4.1.4 Digital diameter gauge

The measuring range is not less than 50mm, and the accuracy is at least 0.05mm.

4.2 Calibration

Add the abrasive to the test apparatus and collect it under the grinding wheel in a container with a volume of not less than 4L. Open the valve and run for 60s ± 1s. Turn off the power and verify that the actual abrasive flow rate should be maintained at 4.0 L ± 0.1 L.

4.3 Test Samples

4.3.1 Small-sized products can be used for test samples. For large-sized products, test samples with dimensions of not less than 100 mm x 70 mm and with decorative surfaces should be prepared. Samples. Six samples shall be prepared from the same batch. For samples with anisotropic surfaces, the relationship with the test direction shall be noted.

4.3.2 The decorative surface of the specimen should be flat, and the flatness tolerance should be less than 1 mm.

4.3.3 The sample was dried in a forced-air drying oven at 65°C ± 5°C for 48 hours, and then cooled to room temperature in a desiccator.

4.3.4 Before testing, use a hard brush to remove dust or sand from the decorative surface of the sample to keep the sample clean.

4.4 Test Procedure

4.4.1 Fill the storage hopper with white corundum abrasive with a particle size of 0.25 mm (moisture content less than 1%) that meets the requirements of GB/T 2479. From Remove the fixture carriage from the grinding wheel, install a pad under the sample, and fix the sample on the fixture carriage so that it is tangential to the grinding wheel. The grinding groove is positioned a distance from the sample. Each side of the sample should be at least 15mm larger than the standard side.

4.4.2 Bring the sample into contact with the grinding wheel, open the control valve and start the rotary motor simultaneously, so that the grinding wheel reaches 75 revolutions within 60s ± 3s, and visually inspect it. Check the uniformity of abrasive flow rate during the test. After the grinding wheel rotates 75 revolutions, the grinding wheel and abrasive stop simultaneously.

4.4.3 Repeat the process in 4.4.1 to 4.4.2, and perform two tests in different areas of each sample to complete all tests of a set of 6 samples.

4.4.4 Place the sample under a magnifying glass, and use a pencil with a lead diameter of 0.5 mm and a hardness of 6H or 7H, along with a steel ruler, to draw the two outer edges of the groove. The outline lines (1 and n) are shown in Figure 3. Draw a line (AB) perpendicular to the center line of the groove at the midpoint of the groove, using a digital diameter gauge or similar instrument. The measuring tool measures the distance between the inner sides of points A and B, accurate to 1 mm. Using the same method, measure the distance C at a point 1 mm ± 1 mm from the end face of the groove. The distance between point D and point D is accurate to 0.1 mm.

4.5 Test Results

The arithmetic mean of the three measurements for each groove is taken as the test result for that groove, and the maximum value of the groove on each specimen is taken as the specimen's result. The results are accurate to 0.1 mm. The arithmetic mean of each group of samples is used as the test result, accurate to 0.5 mm.