Atmospheric aging test is used to evaluate the durability of the coating to the atmospheric environment, and the result is a comprehensive reflection of the various properties of the coating, which determines the service life of the coating.
According to the provisions of GB/T1767-89, the sun exposure site should be selected to represent a place with the harshest climate or under environmental conditions similar to practical applications, such as coastal areas and industrial areas. The surrounding area of the sun exposure field should be open, the field should be flat, and the local natural vegetation should be maintained. The distance between the far-high obstacles should be at least three times the height of the obstacles.
The sun exposure field in the coastal area should be located in a representative place by the sea, and the sun exposure field in the industrial climate should be located in the factory area. The selection of the exposure site should make the sample fully affected by various factors of the atmosphere.
Meteorological observation stations should be set up in the sun exposure field of Yuangao Meteorological Observatory (station), especially to record the amount of ultraviolet radiation, the type and content of corrosive gases or the content of sodium chloride, etc.
The test plate for exposure to Japan is 150mmx250mmx(0.8~1.5)mm cold-rolled steel plate, 1~2mm thick Ly12 aluminum alloy plate, MB8 magnesium alloy plate or other actually used plates (such as plastic plates, wood plates, etc.). The standard sample size for comparative testing is 70mmx150mm.
Check every half a month for the first 3 months of exposure; check once a month for 3 months to 1 year; and check every 3 months after one year. Check for loss of gloss, discoloration, pulverization, mildew, etc., and terminate the test when the scheduled time or when any of the "poor" items in the comprehensive rating method for weather resistance of paint films in GB/T1766-95 are reached.
In order to speed up the atmospheric aging test, various countries have made the following improvements on the device, using reflectors to strengthen the light effect; the solar exposure west frame automatically tracks the sun rotation device, and the timing and quantitative water spray device. Atmospheric aging accelerated testing machine is used, which greatly speeds up the atmospheric aging test speed. For example, the American EMMAQuA testing machine (reflective rate 83%) is equipped with a reflector, an automatic tracker, and sprays wine and steamed water 7 times a day for 10 minutes each time. Atmospheric accelerated aging machine, the test speed is 6~12 times faster.
