Introduction of coating impact strength inspection method

The impact strength of the coating refers to the degree of reshaping of the coating under the action of high-speed load, which reflects the adhesion of the coating to the substrate. When testing the impact strength, the coating can be coated when it is bent or bent during impact. For samples that are bendable during impact, the damage of the coating after impact depends on its own elasticity and the force with the base material; while for samples that are not easily bendable during impact, the damage of the coating is not only related to Its own strength is related to its adhesion to the base material, and it is also related to its static hardness. Therefore, it is very necessary to test the impact strength of coating samples subjected to mechanical impact in the use environment.           

1. Test equipment and its technical indicators

(1) Test equipment The impact strength of the coating is measured by an impact Tester. According to the standard requirements, the impact strength of the coating is expressed by the product of the weight of the weight and the maximum height that falls on the sample without causing damage to the coating.

(2) The main technical indicators of the instrument

a. The required scale on the slide should be equal to 50 cm, 0.1 cm, and the division is 1 cm.

b. The mass of the heavy aid is 1000 g, 10g, and it can move freely in the slide.

c. There is a steel ball on the impact hammer, its diameter is 8mm±0.062mm.

d. The center of the impact is aligned with the center of the concave cavity occupied by the iron stone. The depth of the punch entering the concave structure is 2 m±0.1mm.

e. The four precision of the anvil should be smooth and flat, with a diameter of 15mm±0.3mm. The radius of the concavity rate of the precision edge is 2.5-3.0mn.

2. Calibration of the instrument

The impact testing machine needs to be calibrated professionally before use. When correcting, remove the slide cylinder, put a metal ring with a thickness of 3 mm on the upper end of the punch, and put a metal ring with a thickness of 1mm±o.o5mm on the surface of the anvil. Use an object with a smooth bottom to press down from the upper part of the punch, adjust and press the silver mother so that the upper part of the punch is flat with the metal, and the turning ball at the lower end is just in contact with the metal sheet, then the punch enters the iron and drills into the groove The depth of printing is 2mm±0.1mm

The surface of the steel ball needs to be clean and smooth, if it does not meet the requirements, it should be replaced in time.

3. Measurement method

(1) Each sample is prepared according to the standard requirements, and the tinplate sheet with a specification of 50mX120mmX 0.2~0.3mm is used. After the coating is carried out under the condition that the process requirements and operating conditions are consistent with the production, it is used as a sample for backup.

(2) Determination of impact strength Place the sample coating upward on the iron frame, the impacted part should be no less than 15mm from the edge of the sample, and the distance between each impact point and edge should not be less than 15mm. Then, the weight is controlled by the Keep the device at the height specified in the product standard and drop it to the surface of the sample. After the impact, lift the heavy aid, take out the sample, observe the impacted part of the sample with a 4 times magnifying glass, and judge whether there are grains, scratches or peeling, etc. Phenomenon, and the product of the quality of the test and the maximum height without damaging the coating is used to express the impact strength of the sample.

(3) Precautions

a. The test should be carried out under the conditions of constant temperature (20℃±2℃) and constant humidity (relative humidity 65%-70%).

b. The sample needs to be close to the surface of the anvil to prevent the sample from bouncing and affecting the test results when impacted.                                  

c. The specifications of the test metal ring are: outer diameter 30mm, inner diameter 10mm, thickness 3 mm±0.05mm

d. The size of the metal sheet used for the test is 30mmx50mmx0.05xl.0 mm.