What is the difference between black oxide screw and black zinc plated screw?- Suzhou Anzhikou Hardware Technology Co., Ltd.

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Friends who understand the fastener industry all know that in fact, the black oxide screw surface is not the same as black zinc plating, there are differences. Take the material is carbon steel , the surface is generally black oxide and black zinc plating can be done, but the stainless steel, basically is more made of black oxide, basically the stainless steel can’t be made by black zinc plating. Next, the screw manufacturers take you to talk about: the difference of the screws are made by black oxide and black zinc plated.

1. The thickness of the surface coating is different, and the surface coating of black zinc plating will be thicker than the black one. Black zinc plating is an electrophoretic process. After electrification, the electroplating medium in the solution will adhere to the non-standard screw, and the thickness of the coating is about 3-20um.Blackening is a chemical change in the data of the non-standard screw itself, which causes the surface data of the screw to be oxidized into passivation film. The thickness of the passive layer is usually about 3um.

2. After soaking in acid, the phenomenon is different. If the black layer receded and the white layer continues to reflect with the acid, it means that the black zinc is passivated, or it is black oxide.

3. Friction with screws and white paper produces different phenomena, take a piece of white paper and rub hard, black oxide will be therefore fade, nut the black zinc will not.

The above points are difference between black oxide and black zinc plating, I hope to help you. Suzhou Anzhikou Hardware Technology Co., LTD., as a screw manufacturer with 20 years of customized experience, can do different surface plating treatment according to customer requirements.