Application and development of electroplating in automobile industry

Piston, piston ring and connecting rod are three moving parts of automobile engine. The friction loss of electroplating equipment accounts for about 40-50% of the total loss of the engine. Reducing the weight of piston, piston ring and connecting rod and improving its friction environment are of great significance to reduce engine vibration, noise and fuel consumption. In the past, the piston was not subject to any surface treatment or only chemical tin dipping (forming the initial running in layer): the piston ring was chrome plated and Phosphated; the connecting rod was only connected with a screw for oxidation treatment; The bearing bush on the connecting rod is plated with Pb Sn binary alloy and Sn. These electroplating layers can not meet the needs of high speed, high power, compactness and ECR technology development of modern engines.

bearing bush

In order to prevent Sn in the coating from diffusing to the slave body to form brittle phase, it is necessary to add a layer of nickel grid on the slave body on the bearing bush of high-power engine, and electroplating Pb Sn Cu alloy instead of Pb Sn binary alloy coating.

Inlet and exhaust valves

The friction loss of inlet and exhaust valves is about 2% of the engine energy loss of the station. Measures to reduce losses: reduce the structural size of inlet and exhaust valves, and use light materials, such as Qin alloy Depp heat-resistant steel. When working at a high temperature of 750 ℃ and there is friction detection of scales in the exhaust gas of the engine, the Qinzhi exhaust valve will undergo fierce oxidation. Potassium must be carried out on the surface, which is usually treated by molybdenum spraying and salt bath furnace nitriding. Recently, the treatment method that attracted people's attention is isotactic carbonizing, which has little impact on the environment. The tic hardened layer formed on the surface is 50% deeper than the rutting layer treated by heat-resistant steel salt bath furnace μ m. The hardness reaches hv700 Oxidation resistance, wear resistance, heat-resistant steel gas valve, the treatment cost is more expensive than salt bath furnace treatment

Exhaust funnel, silencer

The exhaust system installed on the automobile chassis is subject to environmental corrosion such as the impact of road mud and sand, as well as the scouring and oxidation corrosion of high-temperature exhaust gas above 400 ℃, so the working environment is very bad. The materials of exhaust system are mostly stainless steel and hot-dip aluminum plate. In the process of working and using, the coating of aluminum plate is often blackened and rusted, and grade 5 corrosion occurs in 40 cycles of vehicle corrosion test, and the corrosion resistance is not as good as that of stainless steel. The addition of silicon element cable in hot-dip aluminum plating l can inhibit the growth of iron aluminum alloy layer and improve the processing performance. The service life of hot-dip aluminum plate is related to the thickness of coating, forming process and working temperature.

Shock absorber link

In the past, the shock absorber connecting rod was plated with hard chromium, and the corrosion resistance could not meet the requirements. A few days ago, heef25 micro crack chromium plating process was adopted, and the coating thickness was 20 ± 5 μ； And 10L ± 3 μ Generally, the number of cracks is 400-600 pieces / cm, which plays a positive role in ensuring the corrosion resistance and lubricity of the shock absorber connecting rod. In this process, the current density has an obvious relationship with the number of microcracks, crack morphology and atmosphere infiltration of chromium plating layer. It is generally controlled at 58a / DM2. The design of cylindrical anode and the polishing after plating have an impact on the quality.

Automotive Trim

The decorative parts of modern cars are mostly plastic parts. High grade automotive plastic decorative electroplated parts require high corrosion resistance, thermal vibration resistance and decoration.