Adhesion is the sum of the bonding forces produced by the physical and chemical action of the coating film on the surface of the substrate. If the adhesion is not good, the cold galvanized paint will not be able to bond the substrate, and will not be able to prevent the substrate from being corroded by the outside world. Therefore, the determination of the adhesion of cold galvanized paint is very important, the following is to introduce several adhesion determination methods:
I. Scribing method
In the cold galvanized paint surface with the provisions of the cutter cross-cut longitudinally and horizontally with a spacing of 1mm grid, the total number of grids for the 5 * 5, and then according to the international provisions of the judging standard grading, 0 level for the best, 5 level for the worst.
II. Scratching circle method
The national standard is to use the circle adhesion tester to determine, apply the load to the paddle needle can cut through the paint film, uniformly cut out the length of 7.5cm, the gap in the positive and vice 0.5cm between the line segments, overlapping in turn the tumbling line graphic, so that the cold galvanized paint paint film is divided into an area of different sizes of the seven parts of the cold galvanized paint, if in the smallest grid in the cold galvanized paint paint film is retained to 70% or more, then it is the best.
III . Pull apart method
In the national standard, the tensile testing machine to determine the fixture at a speed of 10mm/min to stretch until the destruction, in order to assess the adhesion of cold galvanized paint and the form of destruction.
Only with good adhesion, in order to form a dense protective layer, and assess the excellent performance of cold galvanized paint factors, in addition to adhesion, but also flexibility, impact resistance, salt spray resistance and other characteristics.