The hardware accessory copper screw is widely used in electronics, electrical appliances, construction and other fields due to its good electrical conductivity, thermal conductivity and processing performance. However, copper is prone to oxidation and rust in a humid environment, which affects the service life and performance of the screw. As an effective surface treatment method, the electroplating process can significantly improve its corrosion resistance and extend the service life of the screw by forming a dense metal or alloy coating on the surface of the copper screw, meeting the application requirements in different environments.
Pre-treatment of electroplating is a key step to ensure that the coating is closely combined with the copper screw substrate and improve the corrosion resistance. First, remove the burrs, oxide scale and other impurities on the surface of the copper screw by mechanical grinding or sandblasting, so that the surface reaches a certain roughness and increases the adhesion of the coating. Then, chemical degreasing is carried out, using alkaline solution or organic solvent to thoroughly remove the oil stains on the surface of the screw to prevent the oil stains from affecting the contact between the electroplating solution and the copper surface. Finally, pickling activation is carried out, and dilute sulfuric acid or hydrochloric acid solution is used to remove the residual oxide film on the surface, so that the surface of the copper screw presents a fresh and active metal state, providing a good base for subsequent electroplating, ensuring that the coating can be firmly attached, and avoiding the reduction of the anti-corrosion effect due to the peeling of the coating.
Selecting a suitable coating material is the core of improving the anti-corrosion performance of copper screws. Common electroplating materials include zinc, nickel, chromium, etc. Galvanizing is a common way to prevent corrosion of copper screws. Zinc can form a dense zinc oxide film in the air, which effectively isolates oxygen and moisture from contact with the copper matrix and plays a good protective role. Among them, the hot-dip galvanizing layer is thicker and has stronger anti-corrosion ability, which is suitable for harsh environments such as outdoor. Nickel plating can form a uniform and bright nickel layer. Nickel has good chemical stability and can effectively block the invasion of corrosive media. At the same time, the nickel plating layer can also improve the wear resistance and aesthetics of the copper screw. The chrome plating layer has high hardness and good gloss, which not only enhances the anti-corrosion performance, but also makes the copper screw have better decorative properties. It is often used in occasions with high requirements for appearance and anti-corrosion. In addition, the use of multi-layer electroplating, such as copper plating first, nickel plating, and finally chrome plating, can give full play to the advantages of each plating layer and form a stronger anti-corrosion barrier.
Accurate control of electroplating process parameters is an important guarantee for obtaining high-quality anti-corrosion coatings. Parameters such as current density, electroplating time, plating solution temperature, and pH value in the electroplating process will affect the quality and performance of the coating. If the current density is too large, the coating will be rough and burnt; if the current density is too small, the coating will grow slowly and the thickness will be uneven. Reasonable electroplating time can ensure that the coating reaches the required thickness, so that it has sufficient anti-corrosion ability. Stable control of the plating solution temperature and pH value helps to maintain the chemical balance of the plating solution, ensure that metal ions are evenly deposited on the surface of the copper screw, and form a dense and smooth coating. For example, in the nickel plating process, the plating solution temperature is controlled at 50-60℃ and the pH value is kept between 4-5, which can obtain a nickel plating with fine crystallization and good performance, effectively improving the anti-corrosion performance of the copper screw.
The post-treatment process after electroplating plays an important role in further improving the corrosion resistance of copper screws. Common post-treatment methods include passivation treatment and sealing treatment. Passivation treatment is to form an extremely thin passivation film on the surface of the coating to further improve the chemical stability and corrosion resistance of the coating. For example, after galvanizing, copper screws are subjected to chromate passivation treatment to form a rainbow-colored or blue-white passivation film on the surface of the zinc layer. This film can prevent further oxidation of zinc and significantly extend the anti-rust time of the screws. The sealing treatment uses organic coatings or wax and other sealants to fill and seal the micropores on the surface of the coating to prevent the corrosive medium from penetrating into the coating, thereby enhancing the anti-corrosion effect. For nickel-plated and chromium-plated copper screws, sealing treatment can effectively improve their corrosion resistance in humid environments and extend their service life.
During the electroplating process, various problems that affect the corrosion resistance may occur. If the coating thickness is uneven, it will lead to a decrease in local corrosion resistance. The metal ions in the plating solution can be evenly distributed by optimizing the design of the plating tank, adjusting the position and shape of the electrodes, and stirring the plating solution to ensure consistent coating thickness. The appearance of pores in the plating layer will reduce the anti-corrosion effect. The porosity can be reduced by increasing the purity of the electroplating solution, controlling the electroplating process parameters, and increasing the thickness of the plating layer. In addition, if the bonding between the plating layer and the substrate is poor, peeling and shedding are prone to occur. The bonding between the plating layer and the copper screw substrate can be enhanced by strengthening the electroplating pretreatment and selecting appropriate electroplating additives to ensure stable and reliable anti-corrosion performance.
The electroplating process of the hardware accessory copper screw can significantly improve its anti-corrosion performance through perfect pretreatment, appropriate plating material selection, precise process parameter control, effective post-treatment, and timely resolution of common problems. With the continuous development and innovation of electroplating technology, more advanced electroplating processes and materials will be applied to the anti-corrosion treatment of copper screws in the future, further improving the performance and life of copper screws in different environments, and meeting the increasingly diverse industrial and life needs.
