Spiral contraction method
The spiral shrinkage test method is to use the change of the radius of curvature of the spiral metal sheet sample during electroplating to test. A stainless steel spiral strip of a certain specification is weighed after the surface is cleaned, dried, and the inner wall is insulated, and one end of the spiral strip is fixed on the instrument. The other end is a free end. Install the spiral belt together with the instrument above the electrolytic tank, so that the spiral belt is immersed in the plating solution for electroplating. After the coating is deposited on the outer wall of the spiral belt, due to the internal stress of the coating, its curvature When the radius changes, the gear connected to the other end of the helix is driven to rotate, and the displacement is amplified, and the corresponding value is read from the pointer position of the instrument dial, and the weight of the spiral test piece before and after electroplating is weighed to calculate the average thickness of the electroplating layer (correlation Instrument: Thickness Gauge), the internal stress of the coating at a certain thickness can be obtained.
