Salt Spray Test Standard Laboratory

Introduction to Salt Spray Test

Salt spray corrosion is one of the most common and destructive types of atmospheric corrosion.

The salt spray test is an environmental test that primarily utilizes artificial simulated salt spray environmental conditions created by salt spray test equipment to assess the corrosion resistance of products or metallic materials.

Salt spray tests are divided into two major categories:

Natural environment exposure tests

Artificial accelerated simulated salt spray environment tests

The artificial simulated salt spray environment test utilizes a type of testing equipment with a specific volume capacity—a "salt spray test chamber". Inside its chamber, artificial methods are used to create a salt spray environment to evaluate the salt spray corrosion resistance quality of the product. Compared to natural environments, the salt concentration of chlorides in this simulated environment can be several or dozens of times higher than that of a typical natural salt spray environment. This greatly accelerates the corrosion rate, significantly shortening the time required to obtain test results for the product.

Classification of Artificial Simulated Salt Spray Tests

(1) Neutral Salt Spray Test (NSS Test)

This is the earliest and currently the most widely applied accelerated corrosion test method. It uses a 5% sodium chloride (NaCl) aqueous solution, with the pH value adjusted to a neutral range (6 to 7) to serve as the spray solution. The test temperature is set at 35°C, and the required deposition rate of the salt spray is between 1 to 2 ml / 80 cm² · h.

(2) Acetic Acid Salt Spray Test (ASS Test)

Developed on the basis of the Neutral Salt Spray test, this method involves adding a certain amount of glacial acetic acid to the 5% sodium chloride solution, lowering the pH value of the solution to around 3. As the solution becomes acidic, the resulting salt spray transitions from neutral to acidic. Its corrosion rate is approximately 3 times faster than that of the NSS test.

(3) Copper-Accelerated Acetic Acid Salt Spray Test (CASS Test)

This is a rapid salt spray corrosion test recently developed abroad. The test temperature is 50°C, and a small amount of copper salt (copper chloride) is added to the salt solution to strongly induce corrosion. Its corrosion rate is approximately 8 times that of the NSS test.

(4) Cyclic Salt Spray Test

This is a comprehensive salt spray test, which is essentially a combination of the neutral salt spray test and a steady-state damp heat test. It is primarily used for cavity-type complete products. Through the penetration of the humid environment, salt spray corrosion is generated not only on the product surface but also inside the product. It involves alternately switching the product between salt spray and damp heat environmental conditions, ultimately assessing whether there are any changes in the electrical and mechanical performance of the complete product.

Reference Standards for Salt Spray Testing

• GB/T 2423.17; IEC 60068-2-11

• GB/T 10125; ISO 9227

• ASTM B 117

• GB/T 2423.18; IEC 60068-2-52

• ASTM B 368

• MIL-STD-202

• EIA-364-26

Application Fields of Salt Spray Testing

• (1) Road Transportation: Electrical and electronic equipment for road vehicles, rolling stock equipment and devices for rail transit, automotive components, etc.

• (2) Computers: Computers, display screens, host units, computer components, precision instruments such as medical equipment, etc.

• (3) Electronic Communications: Mobile phones, RF devices, electronic communication components, PCBs, PCBAs, etc.

• (4) Electrical Appliances: Household appliances, lighting fixtures, transformers, and various other household electrical equipment, instrumentation, medical devices, etc.

(5) Others: Electroplating, coatings, packaging boxes, transportation equipment, etc.