The working principle and types of salt spray tests

The working principle and compliance standards of salt spray test

Salt spray test is a test that artificially simulates a salt spray environment. Compared with exposure tests under atmospheric conditions, it has significant advantages: the corrosive environment can be controlled, and the environmental reproducibility is good; The experimental time has been significantly shortened; It has saved a lot of manpower, financial resources, and material resources. Its development and promotion have been rapid, evolving from simple neutral salt spray tests to various forms such as acetate spray tests, copper salt accelerated acetate spray tests, and alternating salt spray tests. China has adopted the salt spray test as a national standard and provided detailed regulations.

The alternating salt spray test equipment uses saline or acidic saline solutions to accelerate corrosion of materials or products in a certain temperature and relative humidity environment, reproducing the degree of damage suffered by materials or products within a certain time range. Equipment can be used to assess the ability of materials and their protective layers to resist salt spray corrosion, as well as to compare the process quality of similar protective layers. 

It can also be used to assess the ability of certain products to resist salt spray corrosion. The equipment can reach any temperature point between room temperature and 55 ℃ within the experimental workspace and maintain a constant temperature. Conduct salt spray and moisture tests on materials or products within a specified volume of the box, with constant temperature and relative humidity. 

The equipment normally spray at the temperature of 35 ℃. After reaching the specified time, spray stops. The environment inside the equipment box automatically switches to the humid environment of 40 ℃ and 93% for the humidity test. After reaching the specified time, the equipment automatically switches to the temperature of 35 ℃ for spray. After that, the samples may need to be soaked in salt solution for a period of time before the drying test. 

The drying test may use infrared light, It is possible to use equipment to heat and dry, so that the cycle repeats and automatically stops the test after reaching the specified cycle. The material used for manufacturing this equipment is an imported corrosion-resistant PVC plastic sheet for the outer shell, and an imported PP material for the inner liner. It is high-temperature resistant and does not react with saline or acidic saline solutions, which does not affect the test results. 

During the design work of this equipment, the internal and external pressures are balanced, and the salt mist can freely settle inside the box, and can be adjusted to the range specified by national standards. Moreover, the design takes into account the generation of condensate on the top, inner walls, and other parts of the equipment. If it drips onto the test sample, it will affect the test results. So the top cover of this device is designed to be 110° Due to the included angle, during the testing process of this equipment, condensate will not drip onto the sample and affect the test results.

The alternating salt spray test equipment complies with and is applicable to the standard GB/T 2423.17 specifically issued in China for salt spray testing of electrical and electronic products; 1993 GB/T2423.18-2000; Salt spray test standards GB 6458, GB 6459, and GB6460 for metal coatings; The salt spray test standards GB 5938, GB 5939, and GB 5940 are specifically used to assess the electroplating coating of light industrial products; The salt spray test standard GB 1771, which is mainly applicable to paint layers, and other standards currently in use related to salt spray corrosion.