Salt water spray test is one of the corrosion test methods that take atmospheric corrosion as the object. The test piece is exposed to the spray environment of sodium chloride aqueous solution.

The experimental subjects are surface treatment products of metal materials, electroplating and coating films, and the phenomena of corrosion, rust, discoloration, peeling, and expansion are investigated.

This experiment can compress long-term corrosion into a short period of time for evaluation. Due to the impact of acid rain and salt damage in coastal areas, this environmental test is recommended based on the different usage environments of the product.

The steps for conducting a 24-hour salt spray test by lightly touching the switch are as follows:

1、 Strictly implement the operation of acetate spray test to meet the requirements of GBT10125-1997 and GBT6461-2002, and eliminate the influence of human factors on the test results.

2、 (1) The necessary devices for brine spray test are spray room, salt water tank, compressed air feeder, spray nozzle, test piece support, spray room heating equipment and regulating device.

(2) The spray nozzle shall not directly spray the test solution to the sample, and the solution gathered at the top of the spray room shall not drop on the sample.

(3) The test liquid dripped by lightly touching the switch cannot flow back into the salt water bucket and can be used for testing.

3、 Operating Steps

(1) Turn on the power supply of the salt mist machine, set the intake pressure, and adjust the pressure to a pressure of 0.2-0.4MPa;

(2) Set the saturation barrel temperature, and set the saturation barrel temperature controller for neutral and acetate spray tests to 47 ℃ (40 ℃ -50 ℃); The temperature controller of the saturation barrel for copper accelerated salt spray test is set to 63 ℃ (60 ℃ -70 ℃);

(3) Set the temperature of the test chamber for acetic acid and neutral salt spray tests, and set the temperature control of the test chamber to 35 ℃; Copper accelerated salt spray test, with the temperature controller of the test chamber set to 50 ℃;

(4) Set the test time, and set the spray cycle according to the test requirements, such as 24, 48, 72, 96, that is, one cycle is 24 hours, and the two cycles are 48 hours in turn;

(5) Set the spray pressure; Spray pressure is 0.05~0.12MPa;

(6) The placement of the test sample should be such that the main surface of the sample is inclined at a angle of 15 to 30 degrees from the plumb line and parallel to the main direction of flow in the salt mist box. At the same time, the sample should be placed so that the salt mist can settle freely on the sample. The salt solution on one sample should not fall on any other sample, and the distance between the sample and the sample should not be less than 30mm;

(7) Turn on the spray switch to start the test;

(8) After the test is completed, turn off the spray switch and turn on the demist button. After 24 hours, open the test chamber to check the changes of samples after the test chamber has been cleared of fog;

(9) After the test, turn off the power switch

4、 Preparation of experimental solution

(1) Preparation of sodium chloride solution (neutral salt spray): Pour distilled water or pure water (deionized) into a graduated cylinder with a volume of 9.5 liters. Insert the two connectors of the conductivity meter into the water, and confirm that the water is qualified when the pointer does not shift. Weigh 0.5 ± 0.1kg of sodium chloride using a balance. Sodium chloride should be analytically pure, with a NaI content of less than 0.1%. As impurities may contain corrosive components, the impurity content should not exceed 0.3%. Put NaCl into water and gently stir it with a clean Glass rod until it is completely dissolved.

(2) Preparation of acetic acid NaCl solution (acetate mist): Drip glacial acetic acid into the NaCl solution described in 1 using a pipette, and measure the pH value with a pH meter. Before measurement, check the pH meter calibration label. When the value displayed on the test pen stabilizes between 3.1 and 3.3, the solution preparation is completed. Preparation of CuCl 2 acetic acid NaCl solution (copper accelerated acetate mist), adding 0.26g/L CuCl 2.2H 2O to the solutions described in 1 and 2.

5、 Precautions for salt spray test with light touch switch:

(1) During the test, try not to interrupt. If the interruption is caused by midway sampling (samples in different time periods are tested together), the interruption time should not exceed 15 minutes. When sampling, stop spray, stop timing, take samples quickly, cover the box cover in time after taking samples, and restart the test after the temperature reaches the set test temperature.

(2) The fog collection amount is 1~2m/L per hour. If the fog collection amount is high, the spray tower will be lowered, and if it is low, the spray tower will be raised.