The salt spray resistance of the coating film can be measured according to the method in the national standard GB/T177l-91 "Determination of resistance to neutral salt spray of paint film". This standard applies to the determination of the salt spray resistance of paint films. The salt spray Test Chamber is used to control a certain temperature, salt water concentration and time for the test, and the grade is evaluated by the degree of damage to the appearance of the model.
(1) Materials and equipment
Refined table salt, distilled water
Precision pH test paper pH6.1~7.5
Erlenmeyer flask 150mL
Glass] from the funnel diameter 100mm
Balance sense is 0.oolg
The nozzle-type salt spray box controls the salt spray settlement to 0.4~1g/(8ocm2·h).
(2) Measurement method
Prepare 3.5% saline solution with distilled water and adjust the pH value to 6.5~7.2.
Select the base material and supporting primer according to the product standard, and make the board according to GB/T1765 "Determination of resistance to humidity and heat, salt spray, weather resistance (artificial acceleration) of paint film preparation method".
The original state of u recording sample before testing.
The longitudinal direction of the sample plate is 3o° to the direction of salt spray settlement, and a certain gap is maintained between two adjacent sample plates, and the distance between rows is less than 7.5cm.
Start the equipment, and when the temperature in the box reaches 4o℃±2℃, it is OK to start the calculation test. Spray for 15 minutes every 45 minutes. When not spraying, the relative humidity in the box needs to be kept above 9o%. Check once every 48 hours for continuous testing. After two checks, check once every 72 hours. After each check , the position of the template should be changed. Carry out the last inspection according to the number of times specified in the product standard. If there is no product standard inspection time, it can be determined according to the specific situation.
In the continuous test, it is necessary to check the nozzle frequently to keep the salt spray normal. Salt water cannot be recycled.
(3) During sample inspection and rating inspection, take out the sample carefully. Rinse off the salt deposited on the surface of the sample with tap water, and quickly dry it with cold air (or dry it with a towel or filter paper). Check according to GB/T174o "Paint Film Resistance to Moisture and Heat", and evaluate the grade.
