Pretreatment solution used for electroless nickel-phosphorus alloy plating layer on surface of aluminum alloy

Abstract

The invention discloses a pretreatment solution used for an electroless nickel-phosphorus alloy plating layer on the surface of an aluminum alloy, which comprises the following components: 5-40g / L of sodium molybdate, 5-30g / L of sodium hydroxide or 10-40ml / L of ammonia and the balance of deionized water. The pretreatment solution has the following advantages that: the pretreatment solution simplifies the operation steps of nickel-phosphorus deposition to 9 steps from 15 steps, thereby being easy to realize industrialization and improving production efficiency; the pretreatment solution only consists of two substances, thereby reducing cost and improving economic benefits; the pretreatment solution does not need to adopt nitric acid for carrying out zinc withdrawal treatment, thereby avoiding the pollution and the toxication to chemical nickel plating solution, prolonging the service life of the plating solution, avoiding environmental pollution and reducing influences on the health of operation staffs; and the prepared nickel-phosphorus electroless plating layer has uniform densification, good corrosion resistance, high microhardness, firm combination with an aluminum alloy base body, good metal luster and good appearance, thereby providing a good protection effect for the aluminium alloy.

Description

1. Technical field [0001] The invention belongs to the technical field of metal corrosion and protection, and in particular relates to a pretreatment solution for electroless nickel-phosphorus alloy plating on the surface of aluminum alloys. 2. Background technology [0002] The density of aluminum alloy is relatively low, the strength is relatively high, close to or exceed high-quality steel, good plasticity, can be processed into various profiles, but also has excellent electrical conductivity, thermal conductivity and other characteristics, its consumption is second only to steel, so it is a As an important metal material, it has been widely used in aerospace, marine, communication, transportation, military, computer and other fields. [0003] Aluminum alloy has relatively high chemical activity, and its standard electrode potential is very negative, about -1.67 volts. In various environments, especially those containing chloride ions (Cl - ) environment, aluminum alloys...

AI Technical Summary

Problems solved by technology

Wang Airong used pre-plating Zn-Ni alloy layer, and Liu Bo et al. used pre-plating Zn-Ni-Fe alloy layer to replace the secondary zinc dipping process, but a small amount of cyanide such as NaCN and other additives were added to this solution. It is relatively complicated, and there is also a large pollution to the environment, which is very harmful to human health, and the operation is very dangerous

Invention patent 02133822.1 discloses a nickel immersion solution before electroless nickel plating on aluminum and aluminum alloys. This invention simplifies the electroless nickel plating process on aluminum alloys. The solution is cumbersome and time-consuming, and the cost is high

Invention patent 200510100994.5 reports a method for electroless nickel plating on the surface of aluminum alloys containing Si, Cu, and Mg. Although the invention simplifies the process, the processing object is only applicable to aluminum alloys containing Si, Cu, and Mg, and its application range is limited. Moreover, the surface after nickel-phosphorus plating needs to be passivated and dried.