In salt water, the coating film is not only swelled by the action of water, but also strongly corroded by the penetration of chloride ions in the solution, so the coating film may be damaged by many rust spots and corrosion . The salt water resistance of the paint film should be tested for coatings that are prone to corrosive environments , and the salt water resistance test can be used to judge the protective performance of the paint film, GB/T 10834-2008 "Determination of Salt Water Resistance of Ship Paints by Salt Water and Hot Salt Water Immersion Method" Specifies the test device, sample and its preparation, test conditions, test procedures, test results and evaluation, and test report for the determination of the salt water resistance of ship paint and determination of hot brine properties.
During the test, ordinary carbon steel test plates are used. There are 4 test product samples in each group, one of which is a comparison plate. The surface of the substrate is treated by sandblasting or shot blasting until the surface meet the requirements. Paint in accordance with the technical requirements of the relevant paint products or the matching of the paint system, the number of paint coats and the paint thickness required by the paint manufacturer, seal the four sides of the test plate, and apply appropriate protective paint or test paint on the back of the test plate According to the conditions specified in GB/T 9278, adjust the state of the paint film of the sample for 7 days, and put it into natural seawater or artificial seawater for testing. For salt water resistance test, the temperature of salt water is 21°C±6°C; for heat resistance salt water test, the temperature of salt water is 35°C±2°C, soaking for 7 days is a cycle, and the temperature in the last 2 hours of each cycle is 50°C±2 'C hot salt water immersion test.
It should be noted that 3/4 of the test plate needs to be immersed in the test brine, and the position of the sample in the tank should be constantly changed during the test. When inspecting the sample, take the test sample out , rinse the sample carefully with tap water, dry it gently with filter paper or a soft cloth, check for damage, and put it back in the test tank for testing. When the test is completed according to the specified time or cycle, take out the test panel, wash away the salt traces with tap water, dry it gently with filter paper or soft cloth, and check the color loss, discoloration, blistering, peeling, Rust and cracks and other phenomena, and compared with the control model.