Hyundai Kia MS619-08 Cr-free Zn-Al Composite Coatings

Developed by Hyundai-Kia Motors, the oldest motor vehicle manufacturer in Korea, the “ Hyundai Kia MS619-08 Cr-Free Zn-Al Composite Coatings” standard describes the requirements and test methods for chromium-free zinc-aluminum composite coatings. This standard is primarily used for the protection of ferrous metals in automotive components.

The classification and notation of coatings are given in the table titled “Classification and notation of coatings” given in the standard.

In terms of general requirements, the coating should be a uniform metallic grey or black colour and free from blisters, irregular colours, build-up defects, bare spots, tears and discontinuities.

The detailed requirements in this standard are explained in the table titled “Detailed requirements” provided in the standard on the following basis:

• Coating weight (thickness)
• Corrosion resistance (salt spray test)
• Corrosion resistance (cyclic corrosion test)
• Adhesion
• Water resistance after bonding
• Heavy metals and harmful substances

In this standard, test methods are defined as follows:

• Coating weight test: Coating weight should be measured by weight method. However, coating weight measurement can be done by microscopic method.
  • Composite coating weight test: The total coated area of ​​the original sample is determined, and then the sample is rinsed with alcohol or benzene. After the samples are dry, they are weighed to the nearest 50g using a scale for samples weighing about 100~0,001g. After the sample is weighed, each sample is immersed in a 70 percent sodium hydroxide solution heated to 80 degrees ~ 20 degrees before testing for about 10 minutes (until the coating layer is completely melted). After melting, each sample is sufficiently rinsed with alcohol or distilled water, dried, and weighed to the nearest 0,001g using a scale.
  • Top coating weight test: The total coated area of ​​the original sample is determined, and then the sample is rinsed with alcohol or benzene. After the samples are dry, they are weighed to the nearest 50g using a chemical balance for samples weighing about 100g ~ 0,001g. After the sample is weighed, each sample is immersed in an aqueous solution of sodium silicate + deionized water (10:80) heated to 90 degrees ~ 15 degrees before testing for about 85 minutes until the coating layer is completely dissolved. After the sample is washed, it is heated with a gas burner until the coating layer is completely white. After the sample is completely cooled, the coating is washed and removed with a soft brush (toothbrush). After dissolving, each sample is sufficiently rinsed with alcohol or distilled water.
• Corrosion resistance test:
  • Salt spray test: This test shall be performed continuously in accordance with the standards “KS D 9502 Neutral salt spray test”, “ISO 9227 Corrosion tests in artificial atmospheres - Salt spray tests”, “ASTM B117-19 Standard practice for operating salt spray (fog) apparatus” and “JIS Z 2371 Neutral salt spray test methods”.
  • Cyclic corrosion test: This test should be carried out continuously in accordance with the standard “MS 600-66 Test method for accelerated corrosion in complex environments”.
• Adhesion test: This test is applied to check the adhesion quality between film layers. In these tests, a cutting blade, cellophane adhesive tape and a cutting guide are used as equipment. When performing the test, a test panel is left horizontally under the cutting guide and the film is cut until the cutting blade reaches the bare panel. This process is repeated and 100 cross cuts (10 x 10) are made at regular intervals. The cutting blade should be at a 30-degree angle from the panel and each line should be cut at a uniform speed for 0,5 seconds. In cross cut, the cellophane adhesive tape is completely adhered and removed within 5 minutes by holding one end. (Peeled off at a 0,5-degree angle within 45 seconds). This method is applied once in each horizontal and vertical direction. This test method is applied to each painting material adhesion test. This method can be changed to a cross cut test instead of 100 cross cuts (10 x 10). After the tape is peeled off, the condition of the test panel is checked and compared with the criteria in the table given in the annex of the standard.
• Water resistance adhesion test: The sample is immersed in 40 degrees plus/minus 2 degrees distilled water or deionized water for the specified time and removed (fresh distilled/deionized water is used for each test). After leaving the sample at room temperature for 1 hour, the cohesion test of the coating is carried out without cross-cutting. Following the above adhesion test process, a cellophane adhesive tape is completely adhered to the cross-cut pattern, then immediately pulled off and the tape is removed. Then, the peeling status of the film is examined.

When the materials are supplied to the first and practical products, the test report should be submitted to the relevant departments (material and quality control department). When the material, processing condition and suppliers are changed, the test report should also be submitted to the relevant departments (material and quality control department).

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