What are the differences between neutral salt spray test and alternating salt spray test?

Date：2022-09-08 17:25:23Views：828

Neutral salt spray test and alternating salt spray test are two types of corrosion environment test which are frequently used in salt spray test. In most cases, the neutral salt spray test uses a standard salt spray test chamber, and the alternating salt spray test process is more complex, using a composite salt spray test chamber. What are the differences between neutral salt spray test and alternating salt spray test? In addition to neutral salt spray test, salt spray test also includes acid salt spray test, acetate salt spray test, etc. neutral salt spray test and alternating salt spray test are also two types of corrosion environment test that are frequently used in salt spray test. What are the differences between them? Let's have a look!

1、 About neutral salt spray test

1. Scope of application neutral salt spray test is applicable to determine the quality and uniformity of protective coatings and to compare the salt spray corrosion resistance of samples with similar structures.

2. The test requires a temperature of (35 ± 2) ℃, a salt solution concentration of (5 ± 1)%, a pH between 6.5 and 7.2, and a test time of 48h and 96h. Some require a longer test time.

2、 On alternating salt spray test

1. The alternating salt spray test is applicable to the salt spray corrosion resistance of equipment used in the marine environment or in the offshore area, as well as automobile parts and other equipment.

2. Test requirements: temperature (15 ~ 35) ℃, salt solution concentration (5 ± 1)%, each spray cycle is followed by a damp heat storage cycle, temperature (40 ~ 2) ℃, relative humidity (93 ± 3)% For example, there are three spray cycles, each 2h, and each spray cycle is followed by a wet and hot storage cycle of 20 ~ 22h. This condition is a very short cycle in the alternating salt spray test.

3、 Similarities between neutral salt spray test and alternating salt spray test:

1. Pretreatment, condition test, recovery and later detection are required.

2. The temperature of the salt spray test and the concentration of the salt solution are almost the same.

3. In the same pre-treatment operation mode, try to avoid direct contact with the tested sample by hand during pre-treatment.

4. In the later detection stage, it is necessary to judge the appearance of the product and, if necessary, to test the relevant electrical performance of the product.

4、 Differences between neutral salt spray test and alternating salt spray test:

1. The requirements for testing are different. Neutral salt spray is a continuous spray process of constant temperature and salt solution, and alternating salt spray is realized by alternating spray and wet and hot storage cycles.

2. In the recovery process, the small sample of neutral salt spray shall be washed under tap water for 5 minutes, and then washed with distilled water or deionized water. For the alternating salt spray test, in addition to washing under tap water, it is also required to dry for 1 hour under the temperature (55 ± 2) ℃ and cool for 1-2 hours under the specified recovery conditions.

3. The scope of application is different. The alternating salt spray is mainly applicable to the equipment used around the marine environment. In the harsh salt spray environment, the neutral salt spray is mostly used for various types of equipment used on land.

4. According to different severity levels, the alternating salt spray is more severe, and the neutral salt spray is looser.

5、 Judging from the detection results of salt spray test:

1. After the salt spray test, the whole sample shall be free of corrosion. (if there is corrosion, refer to gb6461 for salt spray rating)

2. After the salt spray test, the product shall be able to work normally according to the requirements of the technical specifications.

6、 Test time for salt spray test:

1. More of the conventional neutral salt spray test was tested for 48 hours;

2. For the alternating salt spray test, the test time is rarely 72 hours;

3. For gjb150.11a-2009, the test time is 96 hours.

7、 Basis and test standard of salt spray test

1. Neutral salt spray test: GB / t2423.17-2008, iec60068-2-11

2. Alternating salt spray test: GB / t2423.18-2012, iec60068-2-52:1996

3. Salt spray test: gjb150.11a-2009

8、 What preparations should be made before salt spray test:

1. Ensure that the painting process of all metal parts and coating surfaces of the sample is complete and whether they have been treated with "three proofs" (plastic parts will not be corroded, such as metal parts such as metal surface painting, outlet terminals, screws, etc.)

2. When sending samples, take corresponding protective measures to avoid bumps on the road, which will reduce the anti salt fog level of bumps;

3. After spraying, do not touch the surface of the prototype directly by hand;

4. If the electrical performance of the prototype needs to be assessed, the working state of the product needs to be adjusted to ensure that the prototype can work normally before the test;

5. Whether the various openings of the prototype are large. If the sealing is not good, the salt solution water droplets of spray may enter the shell along the gap, which may affect the electrical performance.

The above is the introduction of neutral salt spray test and alternating salt spray test. If you need electronic detection, please consult!