[China Aluminum Network] With the rapid development of the international automobile industry, automotive aluminum wheel plating, electroless plating technology is rapidly rising in China. The application of direct electroless nickel plating technology has completely broken the aluminum wheel hub only through the secondary zinc immersion treatment can be carried out the traditional process of electroless plating, so that the aluminum wheel without direct zinc immersion can be directly electroless nickel plating. The aluminum alloy direct electroless nickel plating activator is a non-toxic, odorless, non-polluting, special green environment-friendly new product with advanced levels at home and abroad after years of research and development. Electroless nickel plating can be performed directly using a special activator. Compared with the traditional zinc deposition process, it reduces pollution emissions, reduces product costs, and increases the rate of one-time chemical nickel plating. It overcomes the disadvantage that the electrolyte is easily affected by harmful impurities in the secondary zinc dipping solution, the quality of the plating layer cannot be kept stable, the operation procedure of the electroless nickel plating is complicated, the technical difficulty is high, and all the deficiencies of the electroless nickel plating solution are frequently adjusted and replaced. The activated aluminum wheels, like the steel parts, deposit a layer of bright, dense and well-bonded electroless nickel plating on the surface. The thickness of the coating reaches 80-160 microns and the surface of the coating can withstand ultra-fine turning. Therefore, this process is particularly suitable for the electroless nickel plating production line for automobile aluminum wheels. 1. Advantages of Direct Electroless Nickel Plating Process Using Special Activators 1.1 The process flow is simple, easy to use and free of technical difficulties. 1.2 The workpiece can be electrolessly plated with nickel without dipping zinc. 1.3 No pollution of the bath, the product quality is excellent. Bright and dense plating. 1.4 The combination of the workpiece and the coating is good and the finished product rate is as high as 98%. 1.5 The activator will never corrode the work piece, and the activation time can be arbitrarily extended according to the different composition materials. The workpiece can be soaked in the activator. 1.6 Rolling and plating can be used on either manual or automated production lines. 1.7 After activated by special activators, the workpieces can be electroplated with nickel or flash electroless nickel plating only once with or without washing, eliminating the need for complex secondary zinc replacement processes, reducing production processes, increasing production efficiency, and enabling technologies. Management, bath management, and wastewater treatment are all simplified. 1.8 The use of special activators for direct electroless nickel plating requires only 7 processes to complete the entire work. The use of zinc sinkers for secondary zinc dip treatment requires 17 processes to complete the electroplating of nickel. 2. Comparison of old and new technologies 2.1 The traditional aluminum alloy wheel pre-treatment process is: a. Deoiling, wax removal before the processing process: hot dip wax removal --- scrub --- hot water cleaning --- ultrasonic wax removal --- washing --- hot dip degreasing --- washing ---- Washing --- Pretreatment --- Washing --- Washing B. Sinking zinc, zinc removal, and secondary zinc sinking process : Hanging --- Cathode degreasing --- Weak corrosion --- Washing --- Washing --- Washing --- Descaling --- Washing --- Washing --- Pure water --- Once zinc sinking --- Washing --- Washing --- Washing --- Dezincification --- Washing --- Washing --- Pure water --- Secondary zinc precipitation --- Washing --- Washing --- Washing --- Pretreatment --- Washing --- Pure water --- Pre-plated nickel ------Recycling---Washing---Washing---Activation---Pure Water---Catalytic Copper Plating 2.2 New Electroless Nickel Plating Process Using Special Activator: a. Deoiling, wax removal before the processing process: hot dip wax removal --- scrub --- hot water cleaning --- ultrasonic removal of wax --- washing --- hot dip degreasing --- washing ---- Washing --- Pretreatment --- Washing --- Washing b. Hanging --- Cathode Degreasing --- Weak corrosion --- Washing --- Washing --- Washing --- Descaling --- -Washing---Washing---Pure water---Activator activation---Electroless nickel plating 2.3 Uniform and dense plating, strong bonding strength, good quality of plated parts 2.4 Direct electroless nickel plating using special activator, due to no current Influence, the average plating capacity is very strong, no hole can not enter, can be a small pinhole, slag hole plated up, wherever the activator penetrates into the coating, so that after the activated aluminum wheel die-casting aluminum material like steel parts A layer of bright, dense and well-bonded electroless nickel plating is deposited on the surface of the electroless nickel plating. The coating is dense and the quality of the plating is good. 3, A356 die-cast aluminum direct chemical nickel plating test data Plating hardness: microhardness 500-600 2. Plating phosphorus content: 8-10% 3. Plating uniformity: about 5% 4. Plating thickness: 80-200 microns 5. Plating and matrix bonding force: A356 die-cast aluminum alloy was used as the test piece. After electroless nickel plating, the workpiece was heated to 200° C. in an oven and kept at a constant temperature for 2 hours. Then, it was quenched several times in water at room temperature. No blistering was found on the coating. The boring knife method, saw blade method and tape method test are all superior to the secondary zinc leaching process. 6. Corrosion resistance Electroless nickel plating + plating corrosion resistance test for more than 66 hours. (CASS inspection) 7. Photographs of the metallographic structure of the substrate and the coating obtained in the new process specification and flow of direct electroless nickel plating of aluminum alloys (enlarged 100-fold). 4, a one-time pass rate is high, a substantial reduction in product cost 4.1 secondary zinc sink method in the aluminum wheel due to die-casting material composition segregation enrichment caused by the low-potential area is easy to expose plating, blistering, so that a one-time pass rate Has been fluctuating around 80%, and some even lower. 4.2 After deplating the aluminum wheel, polishing and replating nickel will increase the cost significantly. According to investigations, the cost of aluminum wheels that are electroplated with nickel after deplating is three times higher than the cost of a one-time qualified aluminum wheel. After secondary electrochemical nickel plating, the aluminum wheel blank must be scrapped if it fails. Some aluminum wheel companies fail because of one-time pass rate is too low. Some electroless nickel-plated aluminum wheels were qualified at the time of testing, but they were blistering after being stored in warehouses for some time. . Some of them are blisters after the product is sent to a more end-user for a certain period of time. The reason is that in a corrosive environment with a corrosive atmosphere, when the corrosive atmosphere reaches the substrate through pinholes and other defects in the surface layer, the zinc displacement layer is opposite. When the plated metal and the aluminum substrate become anodes, the zinc will be subject to lateral corrosion, and a white powdery substance will appear between the aluminum hub substrate and the plated layer. This will eventually cause problems of blistering and peeling of the plated layer. 4.3 The use of special activators for direct electrochemical nickel plating results in a one-time pass rate for aluminum wheels of more than 98%. There is basically no waste, significantly improving the quality of aluminum wheel products and reducing product costs. It also solved the problem of the low qualification rate of gravity cast aluminum wheel blanks. 5, operation specification 5.1 use method: 1. Activator 20% 2.Temperature 30°C-50°C (in the Pearl River Delta area can be used at room temperature without heating) 3. Time 1-3 minutes 4. PH value 7.0-9.0 5.2 Aluminium Wheels Direct Electroless Nickel Plating Process Wax Removal --- Washing --- Chemical Degreasing --- Washing --- Cathode Degreasing --- Weak Corrosion --- Washing --- Descaling --- Washing -- Activation --- Electroless Nickel Plating --- Post-treatment 6. Work Efficiency: 6.1 Direct Electroless Nickel Plating with Activator Plating acid bright copper work is only required in 7 processes. 6.2 The secondary zincation treatment using zinc sinking agent requires 17 processes to complete the work of plating the acid bright copper. 7. Maintenance of activators The direct electroless nickel activators of aluminum and aluminum alloys can be used for a long time after being supplemented and adjusted. Each liter of activator can handle 10-15 square meters of workpiece. The activator solution is stable and easy to maintain. The activator usually only needs to replenish the concentrate and adjust the pH with ammonia. The consumption of activator is 100d?/100-150ml. Since the workpiece is brought out, if the liquid level drops, the activator can be added to the specified volume in the reduced volume. 8. Clean production and environmental protection 8.1 Electroless nickel plating bath with zinc sinking agent The bath of electroless nickel plating bath is contaminated due to the incorporation of zinc sinking agent. In order to maintain the stability of the nickel bath, it is necessary to constantly adjust and continuously change the bath solution. It wastes a lot of manpower and material resources and adds unnecessary expenses. Moreover, because of the heavy metal ions and poisonous cyanide ions contained in the sink zinc agent, it has been strictly restricted by the environmental protection department. The use of cyanogen zinc sinks pollutes the environment, causing harm to the country and the public. 8.2 Activator Aluminum wheel The direct electroless nickel activator is a non-toxic, odorless, non-pollution, green and environment-friendly new product with a particularly advanced level in the field of electroplating. Electroless nickel plating is performed directly with an activator, which does not contaminate the bath and the bath is stable. The operation procedure is simple, easy to use, and free of technical difficulties. Protect the environment, benefit the country and the people, and benefit the generations. 9. Concluding remarks The advantages of using new technologies for direct electroless nickel plating on aluminum wheels are: The secondary zinc replacement process can be eliminated, simplifying technology management, bath management, and wastewater treatment. After being activated, the aluminum hub can be directly electrolessly plated with nickel or flash electroless nickel plating with or without water washing, which can enhance the bond strength of the coating, reduce porosity, and improve corrosion resistance. The use of an activator for direct electroless nickel plating or flash electroless nickel plating on aluminum hubs completely overcomes intergranular corrosion caused by residual liquids in pinholes, trachoma, small process holes, blind holes, etc. on the surface of aluminum wheel hub parts. Plating and other shortcomings. The great advantage of using an aluminum hub for direct electroless nickel plating activators is that there are both plating layers where the activator is immersed. Thoroughly solved the method of secondary zincation In the aluminum wheel hub electroplating process, due to segregation of the grain boundary of the die-casting material, blistering in the low-potential region caused by the enrichment; in a corrosive environment with moisture, when the corrosion atmosphere passes through the pinholes in the surface layer, When other defects reach the substrate, the zinc displacement layer becomes an anode with respect to the plated metal and the aluminum substrate, which causes lateral corrosion of the zinc. A white powdery substance appears between the aluminum hub substrate and the plated layer, resulting in intercrystalline corrosion of the substrate, resulting in a plating layer. Blisters, peeling problems. The application of direct electroless nickel plating on aluminum hubs and the use of new direct electroless nickel plating processes have resulted in simple operation procedures, ease of use, and technical freedom. The finished product rate is as high as 98%. Protect the environment, benefit the country and the people. Save time, effort, greatly improve the production efficiency, save a lot of money, reduce the operating costs of the company, to the company has brought incalculable comprehensive economic benefits. This will enable companies to keep pace with the times in the global economic recovery and the fierce competition in the automotive aluminum plating industry, and coexist with knowledge innovation.