New Process of Direct Electroless Nickel Plating on Automotive Aluminum Wheels

[China Aluminum Network] With the rapid development of China's auto industry, automotive aluminum wheel plating technology is rapidly rising in China. The new process of direct electroless nickel plating on aluminum wheels is a new technology developed on the basis of A356 die-cast aluminum alloy. It breaks the bondage of the aluminum hub plating, which can only be carried out by the secondary zinc plating process, so that the electroplating of nickel can be carried out directly without electroless zinc plating. It overcomes the tendency of the electrolyte to be affected by harmful impurities in the secondary zinc dipping solution, contaminating the electroless nickel plating solution, making the quality of the plating layer unreliable, the operation procedure of the electroless nickel plating being complicated, and the technical difficulty being high. The electroless nickel plating solution is often adjusted and replaced. All the deficiencies. The activated aluminum wheels, like the steel parts, deposit a layer of bright, dense and well-bonded electroless nickel plating on the surface. Therefore, this process is particularly suitable for automotive aluminum hub plating production lines.

First, test data:

1, binding force

The test piece was A356 die-cast aluminum alloy. After electroless nickel plating, the workpiece was warmed to 200-300 degrees 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 plated layer. The boring knife method, saw blade method and tape method test are all superior to the secondary zinc leaching process.

2. Corrosion resistance

The coating is resistant to salt spray for more than 66 hours. (CASS inspection)

Second, the bath stability, environmental awareness ratio:

1, sink zinc agent

Pre-plated nickel baths cause pre-plated nickel baths to be contaminated due to the incorporation of zinc sinks. In order to maintain the stability of the baths, constant adjustments and constant bath changes are required. 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.

2, activator

The direct electroless nickel plating activator for aluminum wheels is a non-toxic, odorless, non-polluting green environmental protection product that is particularly advanced 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. A small amount of activator is brought into the electroless nickel plating bath, which promotes the autocatalytic function of the electrolyte and enhances the bonding force between the aluminum substrate and the plating layer. The operation procedure is simple, easy to use, and technically troublesome. Protect the environment, benefit the country and the people, and benefit the generations.

Third, work efficiency:

1. The use of activators for direct electroless nickel plating requires only 7 processes to complete the electroplating of acid bright copper.

2. The use of zinc sinking agent for secondary zinc immersion treatment requires 23 processes to complete the acid bright copper work.

3, the use of activator for plating can increase work efficiency by more than one third.

Fourth, the ratio of activator and zinc sinker price:

According to an annual output of 150,000 aluminum wheel plating production lines, the surface area of ​​each aluminum wheel hub is 1 square meter, totaling 150,000 square meters.

1, activator treatment

Each litre of activator can handle an area of ​​20-25 square meters, about 7500 liters of activator a year. The price of activator per liter is 40.00 yuan, and the total annual amount is about 300,000 yuan.

2, Shen zinc treatment

Zinc removal agent per liter can handle about 3 square meters without supplementation.

If supplements can only handle 10 square meters more. Annual need to sink 15000 liters of zinc. (About 1.5 kg per liter of zinc sinking agent, and 22.500 kg of zinc sinking agent per year. The price of zinc sinking agent per kg is 60.00 yuan, and the price per liter is 90.00 yuan). The total amount is about 1.35 million in the whole year. Aluminum wheel direct electroless nickel activator can be used for a long time after being supplemented and adjusted. The sink zinc agent can not be used for a long time. The use of direct electroless nickel activators can save companies about 1 million yuan annually. (The above price is a virtual price)

V. How to use:

Activator 300-400 ml

Deionized water 600-700 ml

Operating time 3 minutes

Operating temperature 30-50 degrees

PH value 6-7 Note: adjust the PH value with ammonia

Six, operating specifications:

1, aluminum wheel direct plating process

In addition to wax - washing - cathode degreasing - washing - weak corrosion - washing - descaling - washing - activation - electroless nickel - washed - copper plated - washed - semi-bright nickel - high sulfur nickel - bright nickel - nickel seal - Washing - chrome plating

2, aluminum wheel secondary zinc plating process

In addition to wax - washing - cathode degreasing - washing - weak corrosion - washing - descaling - washing - a sinking zinc - washing - dezincification - washing - secondary zinc sink - washing - pre-nickel plating - washing - copper plating - washing - Semi-bright nickel - high sulfur nickel - bright nickel - nickel seal - washed - chrome

3, aluminum wheel flash electroless nickel process

Weak corrosion - Washing - Descaling - Washing - Activation - Flash electroless nickel plating - Washing - Acid activation - Washing - Plating acid bright copper or other metals

The advantage of applying new technology directly to electroless nickel plating on aluminum wheels is that it can eliminate the secondary zinc replacement process and simplify the technology management, bath management, and waste water treatment. After the aluminum hub is activated, it can be electrolessly plated with nickel or flash electroless nickel plating with only one wash or no washing, which can enhance the bond strength of the coating, reduce the porosity, and improve the corrosion resistance. The use of an activator for direct electroless nickel plating or flash electroless nickel plating on aluminum hubs completely overcomes the intergranular corrosion caused by the presence of residual liquids in pinholes, trachoma, small process holes, and blind holes on the surfaces of aluminum 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 lateral corrosion between the substrate and the coating caused by the secondary zincation process, and eventually caused the problem of peeling of the coating.

The application of direct electroless nickel plating on aluminum wheels and the use of new direct electroless nickel plating technology have resulted in simple operation procedures, easy use, and no technical problems. 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.

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