Electro-galvanizing is a surface treatment process used to coat metals such as steel with a layer of zinc to improve their corrosion resistance. Salt spray testing is a standard test method for evaluating the corrosion resistance of electro-galvanized zinc coatings, usually following international standards such as ASTM B117 or ISO 9227.
Author: Anna
Electro-galvanizing is a surface treatment process used to coat metals such as steel with a layer of zinc to improve their corrosion resistance. Salt spray testing is a standard test method for evaluating the corrosion resistance of electro-galvanized zinc coatings, usually following international standards such as ASTM B117 or ISO 9227.
The basic process of salt spray testing is to create a salt spray environment in a closed salt spray chamber using a 5% aqueous sodium chloride solution sprayed by compressed air to simulate the corrosive effects of oceanic or high-salinity atmospheric conditions. The specimen is placed in the salt spray chamber and after a certain period of continuous or cyclic exposure, the corrosion on the surface of the sample is observed and measured as a means of assessing the protective ability of the plating.
The key parameters of an electroplated zinc salt spray test include:
Test Cycle: typically ranges from a few hours to hundreds of hours, depending on material requirements and the purpose of the test.
Salt Spray Chamber Temperature: Typically maintained at around 35°C.
Salt spray deposition rate: 1~2mL of salt spray solution should be collected per hour per 80-100cm² area.
Salt spray pH: control between 6.5 and 7.2.
At the end of the test, the specimens are rated according to the change in appearance, the time of appearance of red rust, the degree of white rust, and possible blistering and flaking to determine the corrosion resistance level of the electroplated zinc layer. These data are important references for selecting the appropriate plating process and coating thickness.