In order to check the reproducibility of test results of test equipment or similar equipment in different laboratories, the salt spray test chamber shall be verified according to the following regulations.
1. Neutral salt spray test (NSS test)
Reference sample: The reference sample uses four cold-rolled carbon steel plates, and its surface quality should meet the requirements of Group 1 of Grade A accuracy in GB5213. The plate thickness is 1mm ± 0.2mm, and the sample size is 50mm * 50mm. The surface roughness of the sample is Rn = 1.3µm ± 0.4µm. Take samples from cold-rolled steel plates or strips. The reference sample is put into the test immediately after careful cleaning. In addition to the provisions of 6.2 and 6.3 in the GB / T10125-1997 standard, all dust, oil or other foreign substances that affect the test results should be removed. The cleaned sample is blow-dried and weighed to the nearest ± 1 mg, and then the back of the sample is protected with a peelable plastic film.
Reference sample placement: The sample is placed in the four corners of the box, with the unprotected side facing up and at an angle of 20º ± 5º from the vertical. The top edge of the sample is at the same level as the top of the salt spray collector. Note: It is possible to suggest the angle of other specifications (for example, 30º ± 5º)
The reference sample holder is made of or coated with an inert material (such as plastic). The upper side of the reference sample should be at the same level as the upper part of the salt spray collector.
Determination of mass loss: After 96h of the test, remove the protective film on the back of the sample and use a 1: 1 (volume ratio) hydrochloric acid solution (p20 = 1.18g / ml) to which 3.5g / l of hexamethylenetetramine is added Corrosion inhibitor, soak the sample to remove the corrosion products, then wash the sample with water at room temperature, then wash with acetone, dry and weigh. The sample is weighed to the nearest 1 mg and the mass loss (g / m2) is calculated.
Operation test of neutral salt spray device: The mass loss of each reference sample is within the range of 140g / m2 ± 40g / m2, indicating that the salt spray box is operating normally.
2. Acetic acid salt spray test (AASS test)
The GB / T10125-1997 standard does not have an experimental procedure for measuring the corrosion of the acetate spray test chamber.
3. Copper accelerated acetic acid salt spray test (CASS test)
Reference sample: Use four nickel plates as reference samples. The sample meets the requirements of 3.1 of ISO6372-1: 1989 (the total amount of nickel and diamond is not less than 99.0%, of which cobalt is not more than 1.5%, iron is not more than 0.5%, oxygen is not more than 0.4%, and other is not more than 0.3%), its size 100mm * 75mm, 1mm ± 0.2mm thick, cut the sample from the plate.
The sample is first cleaned according to the provisions of 6.2 in the GB / T10125-1997 standard, and then soaked in 1: 4 (volume ratio) hydrochloric acid solution at 21 ~ 24 ℃ for 2 minutes, and then rinsed with warm flowing water at a temperature of 105 ℃ The oven is dried, cooled to room temperature and weighed. In the test, the nickel plate can be used repeatedly after being processed by the above method. The weight of the sample is accurate to 1mg, and the back of the sample is protected with a peelable plastic film.
Reference sample placement: The reference sample placement is the same as the neutral salt spray test reference sample placement.
Determination of mass loss (mass per unit area): 24 hours after the test, rinse the surface of the nickel plate with cold water to deposit salts, and then soak in a 1: 4 (volume ratio) hydrochloric acid solution at 25 ° C ± 2 ° C for 2 min to remove corrosion products. Rinse in flowing water at a temperature of 40 ° C ± 5 ° C, dry in an oven at a temperature of 105 ° C, then cool to room temperature and weigh. Weighing is accurate to 1mg. Note: The sample fixture should be made of nickel or Monel or other inert materials.
Operation test of the copper accelerated acetic acid salt spray device: the mass loss of each reference sample is within the range of 7.5g / m2 ± 2.5g / m2, indicating that the salt spray test machine is operating normally.
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