Advantage and challenge
Project advantagesElectroplating Process Analysis:1. Alkali liquor degreasingThe chemical action (saponification) of alkali is used to remove the grease and slight rust on the metal surface. This method is often used to remove ferrous metals such as steel, nickel, copper, and nonferrous metals insoluble in alkali solution. The main components of alkali liquor include sodium hydroxide, trisodium phosphate, sodium silicate, sodium carbonate, sodium sulfate, etc. Among them, sodium hydroxide plays the role of saponification and washing. The concentration of sodium hydroxide determines the washing effect and has a great impact on the subsequent process. Therefore, PH detection is very important in this process!Model selection: PH controller+PTFE electrodeFunction: After the alkali liquor is degreased, the workpiece needs to be carefully rinsed. The common alkali cleaning aids are sodium hydroxide, soda ash, sodium silicate, and sodium tripolyphosphate. As alkali agents, sodium hydroxide and soda ash are the cheapest, and wastewater is difficult to treat. Sometimes the washing objects are damaged due to the strong alkalinity. On the other hand, sodium hydroxide and soda ash have no emulsification effect on the cleaning of mineral oil, so online PH is needed to monitor the PH value of the detergent aidNote: The PH electrode needs to be a tetrafluoro electrode, not a conventional plastic shell electrode, or it will be corrodedAdvantages: in the process of alkaline washing, alkali is directly added for cleaning, and a small amount or excessive amount will lead to a poor cleaning effect, so the online PH can well regulate the PH value to achieve a better effect of oil removal.2. Three-stage countercurrent rinsing (wastewater containing chromium and zinc)The so-called multi-stage dynamic countercurrent rinsing has three characteristics: first, the cleaning tank is not a single tank, and the workpiece needs to go through multiple cleaning steps one after another; Secondly, the cleaning water is not static but in a series of cleaning tanks, supplying water from the last cleaning tank and draining water from the first cleaning tank; Third, the direction of the workpiece to be cleaned is opposite to the direction of the water flow, which is in reverse motion. Although multi-stage dynamic countercurrent rinsing can not achieve zero discharge of cleaning water, three-stage countercurrent dynamic rinsing has an obvious water-saving effect. Of course, this process will involve sewage discharge! A flowmeter is required.Model selection: PTFE lining+titanium alloy electrodeFunction: During wastewater discharge, it is necessary to detect the flow of wastewater, and an electromagnetic flowmeter is requiredNote: The discharge of wastewater is mostly self-flowing. To ensure full pipe, the installation position of the electromagnetic flowmeter should be notedAdvantages: The wastewater treatment in the electroplating park needs to be metered if it is charged. The electromagnetic flowmeter meets the needs of most sites in terms of corrosion resistance and high accuracy.3. Hydrochloric acid pickling activationChemical methods are used to remove rust and oxide film on the surface of the substrate, so as to make the workpiece surface in an activated state. Although sulfuric acid or hydrochloric acid can be used as a pickling solution, hydrochloric acid is mostly used in hot galvanizing production. The reason for this is that hydrochloric acid pickling can be carried out at room temperature. Hydrochloric acid has strong chemical dissolution on metal oxides, and can effectively perform pickling on multiple metals. In the greenhouse, hydrochloric acid dissolves and pickles the iron matrix of iron and steel workpieces faster than sulfuric acid, and the pickling time is shorter, so it is easy to conduct picklingEffective control. Therefore, it is not easy to cause "over corrosion" and "hydrogen embrittlement" when using hydrochloric acid to pickle steel workpieces.Model selection: PH controller+PTFE electrodeFunction: Because an acid solution is required to remove oxide skin and rust on the metal surfaces, PH is required to control the amount of acid added to avoidCorrosion has occurred. There is also acid mist generated, which needs to enter the acid mist spray tower for neutralizationNote: The acid pickling inhibitor must be added during acid pickling to prevent the acid from corroding the metalAdvantages: The range of PH to be controlled can be precisely set to effectively control the amount of acid addedModel selection: PTFE lining+tantalum electrodeFunction: The amount of acid liquor needs to be measured in the process of pickling. In the later stage, it can save costs and can be combined with the PH meter to achieve a better pickling effect.Note: The flow rate in the process of adding acid solution will not be too high, so the electromagnetic flowmeter needs to be calibrated specifically for a low flow rate.Advantages: electromagnetic flowmeter measurement, which can monitor the flow in real-time and optimize the production processSummary
Electroplating refers to a surface processing method in which the cation of pre-plated metal in the plating solution is deposited on the surface of the base metal through electrolysis in a salt solution containing pre-plated metal, using the plated base metal as the cathode! Zinc is a very active metal, which is extremely easy to be oxidized. However, zinc oxide is not a loose powder like iron oxide, but a dense surface layer, which prevents the internal zinc from further oxidation. When the surface layer of galvanized steel sheet is damaged and the iron surface inside is exposed, zinc is more active than iron, so according to the chemical battery principle, zinc will be oxidized before iron, thus protecting the iron layer from damage.