｜Introduction to salt spray test

1. Why do we need to measure salt spray test?

The salt spray test is an accelerated corrosion resistance evaluation method in artificial atmosphere. It atomizes salt water of a certain concentration and then sprays it in a closed thermostatic box, and observes the changes of the tested sample after being placed in the box for a period of time. It reflects the corrosion resistance of the sample being tested. It is an accelerated testing method, which means it takes a short time. It does not take several years, but only a few days or even hours.

2. Which products require salt spray testing?

Metals and their alloys

metal covering

organic cover

anodized film

Electrical and electronic products

3. Covering layer

1) Covering type

Organic coatings, such as paint, varnish, powder coating, anti-rust oil, etc.

Metal coating, such as electroplating, chemical plating, ion plating, spray plating, hot dip plating, chemical vapor deposition, etc. Commonly used electroplating layers include zinc plating, copper plating, nickel plating, chromium plating, tin plating, brass plating, lead-tin alloy plating, etc.

2) The role of covering layer

Aesthetics For example: bright chrome plating

Protect base metal from corrosion

4. Classification of test methods for salt spray test

Neutral salt spray test (NSS)

Acetic acid salt spray test (AASS)

Copper Accelerated Acetic Salt Spray Test (CASS)

5. Commonly used standards:

ISO 9227:2022

ASTM B117-2019

GB/T 2423.17-2008

6. Test conditions

Sodium chloride solution concentration 50g/L± 5g/L

PH value is 6.5~7.2

The temperature inside the test chamber is 35 ±2°C

The salt spray settling rate is 1.5±0.5mL per 80cm² per hour

7. Sample preparation

The type, quantity, shape, and size of the specimen are determined according to the product standards. If there is no standard, it shall be negotiated by the relevant parties.

The sample must be cleaned using appropriate methods before testing, but the protective organic film intentionally coated on the sample should not be washed away.

For cut specimens, the cut area should be protected with paint, paraffin wax or tape.

8. Test time

The test time is determined according to different product specifications. Generally speaking, it is 2/4/6/8/24 hours. If it is greater than 24 hours, it is an integer multiple of 24 hours.

9. Sample processing after test

After the test, take out the sample and dry it naturally indoors for 0.5 to 1 hour, then gently rinse it with clean running water with a temperature no higher than 40 degrees Celsius to remove the remaining salt spray solution, and then blow dry immediately with a hair dryer.

10. Introduction to equipment capabilities

Working size 1: 2000*1000*600mm

Working size 2: 1200*1000*500mm