Shanghai Fortune Alloy Co.,Ltd
1, pinhole, pitting and peeling
Continuous electroplating coating has pinhole, pitting and peeling is the most common fault in electroplating, mainly caused by the following reasons.
(1) Improper heat treatment process of continuous electroplating
In the process of machining, the parts surface adhesion of anti-rust grease, cutting fluid, mechanical oil, lubricating grease, grinding fluid, release agent and dust, grinding dust mixed together to form a thicker dirt. If the above dirt is not removed before the heat treatment, the quenching and sintering of the solid grease after the removal of oil and rust is difficult to clean, plating when the bubble attached to the coating on the formation of gas retention type pinhole.
(2) Electroplating of nickel plating before the poor treatment
Heat treatment workpiece surface will inevitably adhere to a layer of oil, when the dust fell on the surface, and mixed with grease, a long time is difficult to clean, so that the surface of the workpiece to form an obvious small oil spots, when plating bubble stranded on the formation of pinhole. In addition, the use of mesh belt resistance furnace quenching, the surface of the workpiece oil and dust and other impurities particles mixed together, burning to form stubborn solid grease, nitrate temper, above grease and nitro salt formed stubborn thermal polymer, electroplating, it is difficult to remove the above dirt completely clean, hydrogen bubble easily adhered to the dirt, difficult to discharge, so that the coating produced pinhole and pitting phenomenon, and as the bubble gradually grew up, the coating will automatically burst, resulting in peeling phenomenon.
2, coating peeling off
There are two possible reasons for this type of failure, one is the poor adhesion between the coating and matrix, the other is the brittleness of the nickel plating layer, and the ductility is small. If the heat treatment is not easy to remove dirt or plating treatment is not complete, dirt inclusions between the substrate and the coating, so that the coating and substrate adhesion is very poor, subsequent assembly processing, prone to peeling off. When the brightener ratio is improper or the quality is poor, the ph value is too high, the cathode current density is too large and the bath temperature is too low, will cause hydrogen ions in the cathode after the reduction, will be the state of atomic hydrogen infiltration of the matrix metal and coating, so that the toughness of the matrix metal and coating to reduce the phenomenon of hydrogen embrittlement. In addition, when the metal impurities in the nickel plating bath and decomposition products too much, it will also cause the coating "hydrogen embrittlement" phenomenon.
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