What types of abrasion tests are commonly used internationally?

Widely used in abrasion resistance test instruments are abrasion test machine, scratch tester, oscillation test machine, linear abrasion meter these four. The development of coating abrasion resistance test method standard, unify and standardize the detection means of different materials and quality requirements, but also for a variety of systematic abrasion resistance test instrument development provides a design basis must be followed. Below, Xi'an R&S will introduce several commonly used abrasion test.

Rotary friction rubber wheel method (Taber test)

National standard GB/T1768--79 (89) in the method and instrument although the working principle is the same, but did not rotate the disk speed to make clear provisions, and the test results are only by the number of grinding revolutions grinding after the loss of coating quality (weight loss method) of a single method of expression. Rotary friction rubber wheel method can be widely used for coatings, plating and metal, non-metallic materials abrasion resistance test, but used as a grinding rubber grinding wheel needs to be frequently trimmed and timely update. The international standard ISO7784.2--97 stipulates that the abrasion resistance of the coating is determined by the rotary abrasive rubber wheel method, i.e., the rotating disk rotational speed is 60r/min, the pressurized arm carries a certain load under the specified test conditions, and the hard rubber abrasive wheels embedded with emery abrasive abrade the surface of the coating, and its abrasion resistance can be respectively determined by the average value of the coating quality loss (weightlessness) after the specified number of grinding revolutions, or by the average value of the abrasion resistance of a coating thickness required to wear a certain thickness of the coating, or by the average of the wear resistance of a coating thickness required to wear a certain thickness of the coating. The wear resistance can be expressed and evaluated by the average value of coating mass loss after grinding by a specified number of grinding revolutions (weightlessness method) or by the average number of grinding revolutions required to wear a certain thickness of coating (revolutions method), respectively. Comparison of the two, loss-in-weight method on the specimen weighing accuracy requirements are strict, but it is not subject to the influence of the coating thickness; and the number of revolutions of the method is intuitive and convenient to determine, do not need to weigh, but the coating grinding thickness of the measurement requirements are very strict.

Test Method of Coating Abrasion Resistance

Coating abrasion resistance refers to the ability of the coating surface to resist certain mechanical action, usually using grinding wheel grinding or sand impact test to determine, it is often subject to mechanical wear in the process of use of one of the important characteristics of the coating, but also with the coating hardness, adhesion, flexibility and other physical properties are closely related. The commonly used test methods for coating abrasion resistance at home and abroad and their main technical characteristics.

Falling sand scouring test method

With this test method, the selection of natural sand abrasive will have a direct impact on the test results, so the hardness, grain size and geometry of the sand particles are strictly required. The national standard GB/T5237.5-2000 stipulates that the standard sand that meets the requirements of GB/T178-77 is used as the abrasive material, and ASTMD968-93 stipulates that the abrasion resistance of organic coatings should be determined by the falling sand abrasion tester, i.e., the natural quartz sand of the specified origin is used as the abrasive material, and the natural sand is passed through the catheter of the tester to determine the abrasion resistance. Abrasive, through the tester conduit from a certain height free fall, scouring the surface of the specimen to wear down the specified area of the unit thickness of the coating of the volume of abrasive consumed (L), and through the calculation of the abrasion resistance coefficient to evaluate the abrasion resistance of the coating. It should be noted that in the use of falling sand scouring test method of the above two standards, although all take the same main technical parameters of the abrasion resistance tester, but due to the use of natural sand abrasive particle size is different, and thus the same outflow volume of 2L abrasive flow rate into not the same, the former are stipulated as 21 ~ 23.5s, the latter stipulated as 16 ~ 18s.

Blasting impact test method

ASTMD658-81 (86) provides for the determination of wear resistance of organic coatings by blast abrasion (sandblasting) test, this method is to regulate the output pressure of the air pump, so that the tester nozzle at the air flow rate of 0.07m3/min to ensure that an average of (44 ± 1) g per minute sprayed out of the diamond beam impact coating, and to wear down the specified area of unit thickness of the coating of the abrasive material consumed by the quality of the mass ( g), and evaluate the abrasion resistance of the coating by calculating its abrasion resistance coefficient. Therefore, it is necessary to use silicon carbide with a particle size range of 75-90μm as the abrasive according to the standard, while the output pressure of the air source and the uniform spraying speed of the abrasive become the decisive factors affecting the test results.

Reciprocating Transportation Abrasion Test Method

After a specified number of abrasions, the abrasion resistance of the coating is evaluated in terms of the reduction in coating thickness (μm) or coating mass (mg) and by calculating its abrasion resistance.ISO8251-87 and JISH8682 both provide for the determination of the abrasion resistance of aluminum and aluminum alloy anodic oxidation coatings by means of the Abrasive Wheel Abrasion Test Machine. This test method is in the specified test conditions, so that the coated layer and glued to the outer edge of the friction wheel abrasive sandpaper for plane reciprocating movement, every double stroke after the friction wheel rotation of a small angle (0.9o), because the method of the test conditions are easy to control, without other methods such as wheel dressing, aging, sand flow rate, the shape of the sand bundles and other difficult to control the problem, and therefore the test results of the reproducibility of the test results is good! In addition, in addition to the coating layer, this method has been widely used in plastics, rubber and metal materials abrasion resistance test.

China has a national standard GB/T1768-79 (89) "paint film abrasion resistance determination method", and in recent years in GB/T5237.5-2000 in the provisions of the sand abrasion testing machine to determine the aluminum alloy building profile surface fluorocarbon paint film abrasion resistance. In summary, it is not difficult to see that at present, domestic and foreign paint coating abrasion resistance test, a variety of methods, each with its own characteristics. Although the evaluation of the above test methods and their application performance people do not have the same understanding, but on the development and promotion of a number of means of testing applications, the use of rotary friction rubber wheel method, sand method and sand blasting method is still more common.

So far, industrially developed countries for different materials have corresponding wear test methods, such as the Japanese Industrial Standard JISH8503 provides for the metal metal film wear resistance test method; JISH8615 describes the abrasion resistance of chromium plating layer test; and such as the American Society for Testing and Materials standard ASTMD968-93 and ASTMD658 -81(86), respectively, with the falling sand method and sand blasting method to determine the abrasion resistance of organic coatings; and in the international standard SO7784.2-97 in the use of rotary friction rubber wheel method to determine the abrasion resistance of color paints and varnishes; in the IS08251-87 and JISH8682 are In IS08251-87 and JISH8682, it is stipulated that the abrasion coefficient of anodic oxide film on the surface of aluminum and aluminum alloy should be determined by abrasion wheel abrasion tester.