Coating evaluations for the automotive industry
Visual evaluations are the core of coating evaluations after testing. We will take a look at the coating surface by means of the unaided eye or by means of stereomicroscopy to search for defects in the coating or any indications of coating degradation. On top of that, results of other measurements like gloss/color can indicate that coating degradation has taken place. It is possible that corrosion proceeds underneath the coating.
To measure how well coating systems resist against this ‘creep’, an artificial defect under the form of a scratch (scribe) is typically applied to the test panels/product before (cyclic) salt spray testing. Afterwards the extent of creep starting at the scratch is determined by dimensional measurements before and after scraping off the coating.
The adhesion of a coating depends much on the pretreatment of the surface before coating and is a major factor of coating failure in practice. Adhesion tests can be performed before and after accelerated corrosion tests to test the impact of exposure conditions to the adhesion of the coating on the substrate.
Beside the evaluations mentioned above METALogic also performs other evaluations like dry film thickness measurements, bend test, cupping test, impact test, pencil hardness test, … . A (non-exhaustive) list of standards that METALogic can perform you will find below:
- ISO 4628-2 (Assessment of the degree of blistering)
- ISO 4628-3 (Assessment of the degree of rusting)
- ISO 4628-4 (Assessment of the degree of cracking)
- ISO 4628-5 (Assessment of the degree of flaking)
- ISO 4628-8 (Assessment of degree of delamination and corrosion around a scribe or other artificial defect)
- ASTM D1654 (Evaluation of painted or coated specimens subjected to corrosive environments)
- ASTM D714 (Evaluating degree of blistering of paints)
- ASTM D610 (Evaluating degree of rusting on painted steel surfaces)
- ISO 2178 (Measurement of coating thickness – magnetic method), ISO 2360 (Measurement of coating thickness — amplitude-sensitive eddy-current method), ASTM D7091 (Nondestructive measurement of dry film thickness of nonmagnetic coatings applied to ferrous metals and nonmagnetic, non-conductive coatings applied to non-ferrous metals)
- ASTM D3359-A and D3359-B (Rating adhesion by tape test), ISO 2409 (Cross-cut test)
- ISO 16276-1 (Assessment of, and acceptance criteria for, the adhesion/cohesion (fracture strength) of a coating — Part 1: Pull-off testing), ASTM D4541 (Pull off strength of coatings using portable adhesion testers), ISO 4624 (Pull-off testing)
- ISO 11664-4 (Colorimetry — Part 4: CIE 1976 L*a*b* colour space), ISO 2813 (Determination of gloss value at 20°, 60° and 85°)
- ASTM D3363 (Pencil hardness test)
Advantages of coating evaluations by METALogic:
- Evaluate important characteristics of your coating system before and after corrosion tests
- Evaluations done in a laboratory with high quality standards: find more information with regard to the ISO 17025 scope of METALogic here.