STD1027, 1375

Accelerated Atmospheric Corrosion Test (Volvo)

This test procedure has been developed to simulate the corrosion processes that take place on vehicles in a road environment, where sodium chloride (salt) is the dominant corrosive element. It is to be applied to the atmospheric corrosion testing of surface coatings and components, and is claimed to give good correlation to outdoor conditions. This test is cyclic in nature, i.e.; test specimens are exposed to changing climates over time.

Test specimens are placed in an enclosed chamber and exposed to a changing climate that can comprise of 3 different climate cycles (variants 1 to 3), in combination with 3 different methods of salt solution exposure (types A to C), making a total of 9 possible test permutations. Details as follows:

Climate Cycle Variant 1

Step 1; 8.0 hours exposure to a constant climate of 90%RH at +35C. Step 2; exposure to a changing climate during which the humidity is reduced to 45%RH at +35C, and this transition must take place within 0.5 hours (this transition time is allowed for within program step 3). Step 3; 4.0 hours exposure to a constant climate of 45%RH at +35C. Step 4; exposure to a changing climate during which the humidity is increased to 90%RH at +35C, and this transition must take place within 0.5 hours (this transition time is allowed for within program step 1).

This complete 12.0 hour cycle is then repeated. The number of cycle repeats and therefore the test duration is variable.

Climate Cycle Variant 2

Step 1; 7.0 hours exposure to a constant climate of 90%RH at +35C. Step 2; 1.5 hours exposure to a continuously changing climate during which the humidity is reduced linearly to 45%RH at +35C. Step 3; 2.0 hours exposure to a constant climate of 45%RH at +35C. Step 4; 1.5 hours exposure to a continuously changing climate during which the humidity is increased linearly to 90%RH at +35C.

This complete 12.0 hour cycle is then repeated. The number of cycle repeats and therefore the test duration is variable.

Climate Cycle Variant 3

Step 1; 7.0 hours exposure to a constant climate of 90%RH at +35C. Step 2; 1.5 hours exposure to a continuously changing climate during which the humidity is reduced linearly to 60%RH and the temperature is increased linearly to +42C. Step 3; 3.0 hours exposure to a constant climate of 60%RH at +42C. Step 4; 1.0 hour exposure to a continuously changing climate during which the humidity is increased linearly to 90%RH and the temperature is reduced linearly to +35C.

This complete 12.0 hour cycle is then repeated. The number of cycle repeats and therefore the test duration is variable.

Salt Solution Exposure Type A

Test specimens are automatically sprayed with an acidified salt solution. A number of spray nozzles, located at high level inside the chamber, spray down directly on to the test specimens in such a way that an overlapping spray pattern is obtained.

When using exposure type A, step 1 in all climate cycle variants shall be replaced by the following on Mondays and Fridays only. Step 5; 1.0 hour exposure to automatic salt spray. Step 6; 7.0 hours exposure to a high humidity climate of >90%RH, in order to maintain the test specimens in a ‘wet’ condition, at a constant temperature of +35C. All other steps shall be as per the original climate cycle variant.

Salt Solution Exposure Type B

Test specimens are manually immersed in salt solution.

When using exposure type B, step 1 in all climate cycle variants shall be replaced by the following on Mondays and Fridays only. Step 5; Remove test specimens from test chamber and manually immerse them in the prescribed salt solution for 1.0 hour. Step 6; After letting any excess salt solution run off the test specimens for a few minutes, place them back in the test chamber for 7.0 hours exposure to a high humidity climate of >90%RH, in order to maintain the test specimens in a ‘wet’ condition, at a temperature of +35C. All other steps shall be as per the original climate cycle variant.

Salt Solution Exposure Type C

Test specimens are manually coated with a layer of artificial dirt containing salt, before exposure within the test chamber. Every third week the test specimens shall be rinsed with water and inspected. If the exposure is to be continued, a fresh layer of artificial dirt shall be applied

The STD1027, 1375 test is also known as the Volvo Indoor Corrosion Test, often abbreviated to VICT.

To select an Ascott chamber suitable for this test click here

 

For further information on Volvo STD standards visit; www.tech.volvo.se/standard

 

 

© copyright 2006 Ascott Analytical Equipment Limited