The test procedure and method are as follows
1. The aluminum alloy cylinder is polished with 240~400 mesh sandpaper and wiped with solvent before use.
2. The test part should be degreased and solvent dedusted.
3. Mix the two-component solvent-free ring glue in the correct proportion, then coat the aluminum alloy cylinder, press it on the surface of the test coating, and rotate it 360° to ensure that all parts are glued.
4. Use adhesive tape to fix the aluminum alloy cylinder on the coating surface, and the two-component epoxy glue should be cured at room temperature for 24 hours; the cyanoacrylate adhesive should meet the requirements of the instructions (strength should be achieved after 15 minutes, and tested within 2 hours) .
5. Before testing, please use tools to cut the coated substrate around the aluminum alloy cylinder
6. Cover the aluminum alloy cylinder with an extensometer, turn the handle to test, and record the failure strength (MPa) and failure state. The bonding strength and bonding state between the coating and the substrate, between the coating and the coating, between the coating and the glue, and between the glue and the cylinder are expressed in percentages.
7. For convenience, ISO 4624 specifies a series of symbols to describe its status:
A - Substrate cohesive failure:
A/B - the adhesion between the substrate and the first coat of paint is broken;
B - Failure of the first coat of paint to bond;
B/C - failure of the bond between the first layer and the second layer;
Cohesive failure of the Nth coating layer in the N multi-pass coating system;
The adhesion between the nth layer coating and the mth layer coating in the n/m composite coating system is destroyed;
-/Y - failure of the bond between the last coat and the adhesive;
Y - Adhesive cohesion failure;
Y/Z - Bond failure between adhesive and test cylinder.
Adhesion strength is expressed in N/mm2 (MPa). For example, when the tensile stress of the coating system is 20MPa, 30% of the coating adhesion between the cylinder and the first layer of coating is broken, and the adhesion between the first layer of coating and the second layer of coating reaches 70% of the cylinder area can be expressed as 20MPa, 30% B, and 70% B/C.
In NORSOK M501 (Rev 4 1999), it is stipulated that the adhesion test of organic coatings requires the use of automatic center pull instruments instead of manual mechanical instruments, and at least 50MPa. Fireproof coatings require cement type to reach 2.0MPa, and epoxy products require 30MPa.
