Coating internal stress test - resistance strain method

Coating internal stress detection--- resistance strain method 

The resistance strain method is caused by the change of resistance wire stretching and knotting. The change of electric trap value is used to measure the internal stress of the test piece. The surface to be picked of the broken steel test piece before the piece size is l00mmx20mmx2 (requires its roughness a.≤0, 4µm), use No. 88 constant compound to paste the resistance strain gauge, weld a certain length of wire, and then use the corresponding insulating paint to completely coat the back of the sample and the strain gauge, and press the head to strictly insulate the green (up to 50 Ma continuous resistance ), after the double-bridge balance by the resistance strain Tester, the internal technology of the sub-electrolytic tank is placed for electroplating at the specified current density and time. When the metal coating is deposited on one side of the sample, due to the internal stress of the layer, the corresponding shrinkage of the formed sheet is caused. , the resistance value changes, the sample is taken out after plating, cleaned and dried, and then measured as a variable indication on the strain gauge, and the internal stress of the coating is calculated according to the following formula: (related instrument: resistivity meter)