Electroless nickel plating process on magnesium alloy surface of a pre-electroplated zinc-nickel alloy

Abstract

The invention discloses a chemical nickel-plating process of a magnesium alloy surface for pre-plated zinc-nickel alloy. The process is characterized by comprising the following steps: washing with alkali; washing with acid; activating; galvanizing; electroplating zinc-nickel; and chemically plating nickel, wherein pre-treatment of chemical nickel plating is performed by adopting zinc galvanizing and zinc-nickel electroplating processes, so that an excellent base is provided to chemical nickel-plating; a small amount of nickel salt is particularly added into the galvanizing solution before chemical nickel-plating for mixed electroplating, so that a proper amount of nickel exists in the pre-plated layer, the subsequent chemical nickel-plating can be performed smoothly, and the binding force of nickel and magnesium alloy can be reinforced.

Description

technical field [0001] The invention relates to the technical field of electroplating, in particular to an electroless nickel plating process on the surface of a magnesium alloy pre-plated with a zinc-nickel alloy. Background technique [0002] As a lightweight engineering structural material, magnesium alloy has high specific strength, high specific stiffness and superior shock absorption performance, and has a wide range of applications in transportation, communication, aviation, aerospace and other fields. However, magnesium alloys have high chemical activity, low electrode potential, and loose oxide film on the surface, resulting in low protection performance, which restricts the application and development of magnesium alloys. This has aroused people's attention to the surface corrosion and protection of magnesium alloy parts, and a lot of research has been done on the surface of magnesium alloys, such as anodic oxidation, chemical conversion film, organic coating, surf...

AI Technical Summary

Problems solved by technology

However, the process is complicated, the repeatability is poor, cyanide is used, the plating solution is poisonous, pollutes the environment, the brightness of the coating and the stability of the plating solution need to be further improved

[0004] In order to overcome the shortcoming of complex process, researchers have developed a direct electroless nickel plating method, such as JP2003073843, which uses chromic anhydride to etch magnesium alloys, performs electroless nickel plating after fluoride activation, and adjusts the electroless nickel plating solution with ammonia water to make it appear Weakly alkaline, once obtained the chemical nickel plating layer with good bonding force and high corrosion resistance, Li Degao et al. used deflocculation → chemical degreasing → light emission → neutralization → activation → pre-treatment in the patent CN1699634A magnesium alloy electroplating method The galvanizing process has obtained a relatively good pre-galvanized layer, and the pre-galvanized solution is cyanide-free, non-toxic and harmless. In the patent CN1737205A, people such as Yang Sheng pickled the magnesium alloy with concentrated hydrofluoric acid (11%) Afterwards, directly electroplate aluminum to obtain a relatively good aluminum coating. Chinese patent CN1641075A has described in detail the surface or activation treatment methods and surface plating methods of magnesium and magnesium alloys. Although these processes are all separated from cyanide electroplating, the treatment before electroplating The process is mostly based on the improvement of the DOW process