Mechanical galvanizing for nail making is an anti-corrosion coating with different process from electrogalvanizing, hot-dip galvanizing and Dacromet treatment. Its process characteristics are: production operation under room temperature, coating formation does not belong to electrodeposition, but the coating is formed by the rotation of the plating cylinder loaded with parts, so that the parts medium in the cylinder collide with each other and realize the industrial energy transfer of nail making machinery; the coating structure is that the micro-spherical zinc powder is deformed by the mechanical force of nail making, and becomes a layered superposition of flat and disc-shaped zinc particles to condense into a coating. This structural coating has the basic physical characteristics of metallic zinc, and the function of the coating is to provide an anodic protective coating for the basic iron parts to prevent rust. The process characteristics are: it does not cause hydrogen embrittlement to high-strength steel industrial parts and heavy anti-corrosion coating for small roll-plated parts to replace hot-dip galvanizing process, which has competitive advantages in industrial application. 1. Parts pretreatment, degreasing and rust removal. For ordinary parts, conventional surface treatment methods can be used, but special attention should be paid to the rust and oxide scale removal of high-strength steel matrix parts, because strong acidic chemical materials containing hydrogen ions cannot be used for a long time to remove rust and oxide scale on the surface of parts. Such treatment will have a certain hydrogen permeation effect on the steel base of the parts. Therefore, mechanical nail making methods should be used to solve the problem: such as sand blasting, vibration finishing, shot blasting, etc.
2. Flash copper replacement: There is no thickness requirement for the replacement copper layer, but it must completely cover the surface of the part substrate. Its function is to improve the bonding strength of the coating, facilitate the uniformity of the coating surface condition, and prevent the penetration of hydrogen generated in the process into the substrate. Another function is that because the copper layer has good electrical conductivity, the galvanized parts of the nail-making machinery with the same zinc coating thickness are compared with the zinc-diffused parts in the salt spray chamber. When the salt spray test reaches 11 cycles, it is found that due to the erosion of the salt spray water flow, the edges and corners of the zinc-diffused parts have red rust, while the edges and corners of the nail-making machinery galvanized parts have exposed the substrate, but the six pieces in the batch do not produce red rust: This is because the resistance of the replacement copper layer is small and the electron conduction is smooth, which ensures the normal electrochemical cathode state of the iron substrate. Therefore, the replacement copper layer is particularly important for the electrochemical corrosion protection of the galvanized coating structure of the nail-making machinery.
3. Nail-making mechanical galvanizing deposition transition bottom layer: This process is for replacing the copper layer. The implementation steps are to add a quantitative amount of nail-making mechanical galvanizing special initiator and a small amount of coating zinc powder into the rolling coating drum. After rolling for 3-5 minutes, a composite galvanized layer that transforms the original copper layer of the parts into a silver-gray can be formed. The quality of the galvanized layer will affect the toughness and bonding strength of the subsequent thickening coating. 4. Nail-making mechanical galvanizing deposition: Quantitative batches of zinc precipitation initiators and coating thickness requirements are required. The zinc powder can be set in this process within 15cm-30min to achieve the anti-corrosion galvanized layer thickness required by industrial parts. 5. Water polishing: The surface of the nail mechanical galvanizing powder is a non-mirror semi-bright coating. The water polishing process is the initiator and zinc powder of the nail mechanical galvanizing. The coating drum continues to rotate to make the surface of the part coating reach a uniform and bright silver-white surface. It generally needs to rotate 5-10in. Although the coating does not reach the mirror gloss of electroplating, the surface smoothness and brightness are better than the hot-dip galvanizing layer. The rotation time of the water-polished plating drum has a maximum value. When it exceeds a certain maximum value, the zinc coating will be cut and damaged to a certain extent.
6. Chrome passivation on the surface of parts: The zinc coating of nail-making machinery, especially under the initial conditions, is prone to produce white corrosion products on the coating surface in humid air. It must be transparent chrome passivation and yellow chrome passivation to prevent the formation of white corrosion products through the formed chromium passivation film. 7. Inspection and acceptance: The thickness and coating quality of the galvanized nail-making machinery industry depend on the process operation, process formula and process qualitative and quantitative standard control: Therefore, the inspection and identification of the coating quality is particularly important. Qualified inspection results will guide the correct production of different batches of parts by the galvanized nail-making machinery process.
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