Double-layer chemical nickel plating solution and process for improving corrosion resistance of magnesium-containing aluminum alloy

Abstract

The invention discloses a double-layer chemical nickel plating solution and process for improving corrosion resistance of a magnesium-containing aluminum alloy. The nickel plating solution comprises a neutral fluorine-containing chemical nickel plating solution which comprises the following components: sodium hypophosphite, basic nickel carbonate, ammonium citrate, lactic acid, ammonium acetate, ammonium bifluoride and the balance of water. The double-layer chemical nickel plating process comprises the following steps: 1) performing zinc dipping treatment on the magnesium-containing aluminum alloy twice; 2) performing neutral fluorine-containing chemical nickel plating treatment on the aluminum alloy after performing the zinc dipping treatment twice; and 3) performing high-phosphorus chemical nickel plating treatment on the aluminum alloy after the treatment in the previous step. According to the process disclosed by the invention, the zinc dipping treatment is firstly performed on the magnesium-containing aluminum alloy twice, the neutral fluorine-containing chemical nickel plating treatment and the high-phosphorus chemical nickel plating treatment are further performed, a salt spray test is performed on a workpiece after the treatment for 24-28h, and the results show that no rust points appear on the surface of the workpiece and the corrosion resistance is very good; furthermore, the phenomenon of decomposition of the plating solution is avoided in the nickel plating process; and in addition, after double-layer nickel plating treatment, a plated layer has relatively strong binding force with a matrix of the workpiece.

Description

technical field [0001] The invention relates to a double-layer electroless nickel plating solution and a process for improving the corrosion resistance of magnesium-containing aluminum alloys. Background technique [0002] Because aluminum alloy has good corrosion resistance and casting performance, it can be used as a demoulding mold for automobile tires. In order to improve the structural strength of aluminum alloy and enhance its casting characteristics, a certain amount of magnesium is often added to the alloy. [0003] However, the corrosion resistance of the aluminum alloy containing magnesium is poor, and the sulfide in the rubber will corrode the surface of the mold during the demoulding process of the rubber and the mold. Therefore, it is necessary to perform high corrosion resistance treatment on its surface. [0004] In the prior art, in order to solve the problem of corrosion resistance of aluminum alloys containing magnesium elements, it is necessary to perfor...

AI Technical Summary

Problems solved by technology

[0005] ①The magnesium element cannot be effectively protected, resulting in poor bonding force of the outermost protective film; ②During the processing of the workpiece, the defective rate is very high, mainly due to the corrosion of magnesium, which leads to the decomposition of the electroless nickel plating solution; ③Simple One-time electroless nickel plating, more porosity, poor corrosion resistance