Process for reducing low internal stress of hub electroplated layer through semi-bright nickel electroplating procedure

Abstract

The invention relates to a process for reducing the low internal stress of a hub electroplated layer through a semi-bright nickel electroplating procedure. In a semi-bright nickel electroplating step, a solution formula consists of 100-150g.dm<-3> of nickel sulfate (NiSO4.6H2O), 10-30g.dm<-3> of nickel chloride (NiCl2.6H2O), 20-30g.dm<-3> of boric acid (H3BO3), 1-2g.dm<-3> of sodium dodecyl sulfate, 1-2g.dm<-3> of butynediol and 0.1-0.2g.dm<-3> of sodium maltodextrin, and the operating conditions are that the temperature is 45-55 DEG C, the pH value is 2-3, the anode current density is 1-3A.dm<-2>, the time is 10-20 minutes, and air stirring and continuous filtration are performed. By adopting the process, a metal coating with high bonding force and high corrosion resistance can be obtained on the surface of a magnesium alloy motorcycle hub, the internal stress of the coating is reduced, and the phenomenon of cracking during use is avoided.

Description

technical field [0001] The invention relates to the technical field of electroplating, in particular to a process for reducing low internal stress of a hub electroplating layer through a semi-bright nickel plating process. Background technique [0002] Magnesium alloy has excellent properties such as light weight, high specific strength, shock resistance and shock absorption, and is considered to be an excellent substitute for aluminum alloy in the automotive industry. Magnesium alloys are used in the automobile industry, which can reduce the weight of automobiles and is an effective way to reduce energy consumption and exhaust emissions. The wheel hub is one of the parts that account for the largest weight of the vehicle. Using magnesium alloy as the material for manufacturing the wheel hub can achieve the purpose of effectively reducing the weight of the vehicle. At present, wheels made of magnesium alloys have been widely used in motorcycles. However, the chemical prope...

AI Technical Summary

Problems solved by technology

[0004] (1) Magnesium alloy cyanide pre-copper plating process uses highly toxic cyanide, which is harmful to human health and pollutes the environment

Dow process, Norskhydro process and WCM process are unstable, the operating window is narrow, and there are many defects in the plated parts after plating

[0005] (2) The direct electroless nickel plating process of magnesium alloy uses a pretreatment solution containing hexavalent chromium Cr(VI) and hydrofluoric acid, which is harmful to human health and pollutes the environment; the electroless nickel plating solution is a thermodynamically unstable system, and the plating The service life of the liquid is short and the production cost is high

This makes the technological process of magnesium alloy electroplating treatment cumbersome and increases the production cost

Therefore, the electro-galvanized layer is generally used as the final coating on the magnesium alloy, and is no longer electroplated for other combined coatings, and its anti-corrosion effect is limited.

[0007] (4) Electroplating copper directly in pyrophosphate solution after zinc immersion in magnesium alloy is prone to poor bonding between copper coating and magnesium alloy substrate

Because the complexing ability of pyrophosphate ions to copper ions is poor, the potential difference between the magnesium alloy substrate and metallic copper is very large. When copper is electroplated in pyrophosphate solution, the substrate magnesium and copper ions undergo a violent substitution reaction, which makes the copper coating Decreased binding to the substrate

The compactness of the pre-plating layer is not enough, and the plated parts are corroded during acid copper plating

[0008] (5) The magnesium alloy metal coating coating technology reported in the literature is only a laboratory result, and there is no electroplating industrial application of magnesium alloy products; most of the research is concentrated on the pretreatment of magnesium alloy electroplating, and the completeness of magnesium alloy combined electroplating technology has not been proposed. Program

[0010] However, the above literature does not study the problem of internal stress

The electroplating layer generally produces internal stress, which will affect the mechanical properties of the hub and cause the hub to crack easily during use.