What are the advantages and disadvantages of silane pretreatment and phosphating pretreatment? Text / Yang Wenliang First, silane treatment Compared with traditional phosphating, silanization has the following advantages: no harmful heavy metal ions, no phosphorus, no need for heating. The silane treatment process does not produce sediment, the treatment time is short, and the control is simple. The processing steps are small, the surface adjustment process can be omitted, and the bath can be reused. Effectively improve the adhesion of the paint to the substrate. But as far as the current domestic technology is concerned, it is not very mature and needs to be improved! Especially in the selection of silanes and auxiliaries, you have to work hard. Silane treatment is a technique that belongs to the combination of ceramic treatment and phosphorus-free conversion technology. Technically speaking, silane treatment is one of the non-phosphorus conversion treatments, and silane treatment technology has begun to fall behind compared with the phosphorus-free conversion agents that have been widely used. Second, phosphating Phosphating is a commonly used pretreatment technology. In principle, it should be treated by chemical conversion membranes, mainly used for phosphating of steel surfaces. Phosphating is a chemical and electrochemical reaction to form a phosphate chemical conversion film. The phosphate conversion film formed is called a phosphate film. The purpose of phosphating is mainly to provide protection to the base metal, to prevent the metal from being corroded to a certain extent; to base the paint before painting, to improve the adhesion and corrosion resistance of the paint layer; to reduce friction in the metal cold working process Lubrication. Third, phosphating and silane cost advantage analysis The high efficiency and energy saving of silane products are mainly reflected in the following aspects: 1. Thermal energy: Phosphating (calculated at a phosphating temperature of 40 to 50 degrees) At present, the domestic thermal energy consumption of spray phosphating line is about 70 yuan / thousand square meters. Silane (heated to more than 15 degrees in winter only) is expected to consume 10 yuan / thousand square meters. Thermal energy: Phosphating is more expensive than silane by 60 yuan / thousand square meters. Calculated by monthly average treatment of 10,000 square meters, phosphating is a total of 600 yuan. 2, kinetic energy: (currently calculated to run 2000 hours per year) Using the silane process, the metering tank pump and the passivation tank pump can be turned off, and the power is calculated at 4.0 kW. The annual electricity bill (calculated at the electricity price of 1 yuan) is 2×2000×4.0=16000 yuan, and the annual calculation is phosphating. 16,000 yuan. 3. Wastewater treatment Phosphate has about 15000 PPM phosphate, zinc, nickel and manganese total about 3000 PPM, and the water washing factor is calculated at 100. When the subsequent water wash reaches the overflow dynamic equilibrium, the wastewater contains about 1500 PPM of phosphate, and the total of zinc, nickel and manganese is about 300 PPM. Processing about 8 yuan per ton of wastewater. The silane contains no phosphorus, the silicon content is about 40 PPM, the zirconium content is about 200 PPM, the water washing factor is calculated at 100, and the subsequent water washing reaches the overflow dynamic equilibrium. The wastewater contains about 4 PPM of silicon, about 30 PPM of zirconium, and less than 1 wastewater per ton of treatment. yuan. The monthly average treatment of 10,000 square meters, about 4L of wastewater per square meter calculation, about 480 tons of wastewater treatment, phosphating a total of 3360 yuan. Phosphating bath treatment will have phosphating slag for a period of time, while silane does not, and no slag removal equipment is needed. In summary, statistics: Based on the annual production of 120,000 square meters, the use of silane products saves RMB 1,490 yuan than phosphating. Fourth, the comprehensive advantage comparison As phosphorus products and zinc, nickel products, and energy prices continue to rise, the advantages of silane products in terms of overall cost will be even more unshakable. In addition, silane products have the following outstanding advantages: 1. Environmental protection Compared with phosphating, silane products do not contain heavy metals such as zinc, nickel and manganese, which significantly reduce water consumption and significantly reduce wastewater treatment. They work at room temperature, contain no phosphorus, do not contain redox agents, and emit no nitrogen oxides. Almost no slag (all metal slag amount <0.1g / m2), due to low slag production, can be completely closed water treatment, recycling water, no wastewater. 2, convenient management The by-product of the phosphating process is a large amount of phosphating slag. At intervals, the production line must be stopped, and the phosphating tank is slag-treated. After the slag removal, not only the phosphating tank but also the phosphating solution is inevitably partially wasted. . The treatment of phosphating slag is also a laborious task. With the use of silane products, all of the above problems no longer exist. In the phosphating process, it is necessary to control various parameters such as free acid, total acid, fluorosilicic acid, and accelerator points, and the silane only needs to control the pH and the activation point. The silane process also eliminates the need for a metering tank, which saves on the chemical consumption and control of the metering tank and makes operation simpler. 3, the price comparison Silane treatment agent Phosphating solution Pharmacy price, yuan / kg 35～40 5~6 Treatment area, m2/kg 200 50 Unit cost, yuan / m2 0.3 0.22 Salt spray resistance test, h 300 1000 Processing temperature, °C Normal temperature (15~35) 50~55 Note: The 24 hours of salt spray resistance test is equivalent to corrosion resistance for 1 year under normal conditions. Zhejiang Hisun Electrical Appliance Co.,Ltd , https://www.cn-hisun.com