Introduction of bending test method for coating bonding force

There are many methods for evaluating and inspecting the adhesion of coatings, which can be divided into qualitative and quantitative inspection methods. 

Qualitative inspection method: According to the type of coating and the use environment of the coating, the qualitative inspection of the coating can be selected from various methods such as bending, filing, impact, scoring, heating or cooling, and cupping.

This article mainly introduces the bending test method

bending test

The bending test method is to cast a method on a rectangular substrate as a sample, and bend the sample under the action of an external force. Due to the difference in stress between the substrate and the substrate, a component force will be generated between the two. When the component force is greater than the combined force , the method layer is peeling off from the substrate or excessive cracking. After the measurement, whether the layer is delaminated or peeled off after the bending test is used to evaluate whether the coating adhesion is qualified. This method is suitable for the coating combination of thin hand parts, wire rods, springs and other products Force test. (Related instruments: bending Tester)

The specific conditions and methods of the bending test are generally as follows.

(1) Bend the sample along an axis whose diameter is equal to the thickness of the sample, and bend it repeatedly 180° until the sample breaks, and it is qualified if the layer does not fall off.                          

(2) Bend the sample repeatedly for 180' along an axis whose diameter is equal to the thickness of the sample, and then check the bent part with a magnifying glass of 4 times. If the legal layer does not peel off, it is a composite

grid

(3) Fix the sample on the platform fault, bend the sample repeatedly until it breaks, if the layer does not peel off, or use a 4 times magnifying glass to check that the coating and the substrate are not delaminated, it is all qualified.

(4) Place the two ends of the sample on the fulcrums, add a cutting load between the two fulcrums, bend the sample, compare the bending curvature and the position of the electric crack at the beginning of the coating after bending, or use a suitable With the same method, scrape and count the color system layer, and then compare the size range and degree of coating peeling off.