Methods of test for metallic and related coatings : Corrosion and Related Property Tests – Wet (Salt Fog)/Dry/Humidity
This test standard comprises of 5 climate modifications to the basic salt spray test. 4 of these are as described below and are known by the following annexes and descriptions:
Appendix A Cycle A
The salt solution is prepared to a concentration of 50+/-10g/L and the pH of the solution shall be in the range of 6.0 to 7.0.
Test specimens are placed in an enclosed chamber, and exposed to a changing climate that comprises of the following 3 part repeating cycle. 2 hours exposure to a continuous indirect spray of salt water solution at 35°C , which falls-out on to the specimens at a rate of 1.0 to 2.0ml/80cm²/hour. This is followed by 4.0 hours exposure to an air drying (purge) climate at 60°C. This is followed by 2 hours exposure to a high humidity climate of 95%RH at 50°C. This climate is maintained under constant steady state conditions. The test cycle can be repeated for 30 cycles (240h), 60 cycles (480h), 90 cycles (720h) or 180 cycles (1440h) cycles. Note: this cycle corresponds with the CCT-2 cycle.
Appendix B Cycle B
The salt solution is prepared to a concentration of 50+/-10g/L and the pH of the solution shall be in the range of 6.0 to 7.0.
Test specimens are placed in an enclosed chamber, and exposed to a changing climate that comprises of several steps starting with a continuous period of 24 hours indirect spray of salt water solution at 35°C followed by 8 hours of wetting at 40°C and 16 hours exposure to ambient conditions. This is followed by a repeat pattern of wetting and exposure to ambient conditions totalling 168 hours. Unless otherwise agreed, the test cycle shall be repeated for 840h.
Appendix C Cycle C
The spray solution is prepared by dissolving sodium chloride and ammonium sulphate in water to give concentrations of 0.31+/- 0.01 g/L and 4.1+/- 0.01 g/L respectively. The pH of the solution shall be in the range of 6.0 to 7.0.
Test specimens are placed in an enclosed chamber, and exposed to a changing climate that comprises of 3.5 hours of spray solution at 30°C, followed by a 3.5 hour step of dry purge at 40°C. A period of 24.5 hours at 75% RH is then followed by a 102 minute step of dry purge at 30°C. Having multiple steps this is then followed by a 3.5 hour exposure of spray solution at 30°C followed by another high humidity soak at the same temperature for just over 6 hours. This is then completed off by two dry air purges of 3 hours at 35°C and 2 hours at 25°C respectively. Unless otherwise agreed, the test cycle shall be repeated for 1000h.
Appendix E Cycle E
The salt solution is prepared to a concentration of 50+/-10g/L and the pH of the solution shall be in the range of 6.0 to 7.0.
Test specimens are placed in an enclosed chamber, and exposed to a changing climate that comprises of the following 4 part repeating cycle. 4 hours exposure to a continuous indirect spray of salt water solution, at 35°C, which falls-out on to the specimens at a rate of 1.0 to 2.0ml/80cm²/hour. 2 hours dry purge at 60°C, 0.5 hours dry purge at 40°C followed by a 2 hour high humidity soak at 50°C. Unless otherwise agreed, the cycle shall be repeated for 4000h.
For further information on AS standards visit; www.standards.com.au
