Pretreatment activation solution and pretreatment method for aluminum and aluminum alloy electroplating

Abstract

The invention provides a pretreatment activation solution and a pretreatment method for aluminum and aluminum alloy electroplating, which include the following components: 20-30 g / L of fumaric acid, 3-5 ml / L of hydrofluoric acid, and water as a solvent. Pretreatment method: degrease and wash the aluminum and aluminum alloy workpieces, then alkali etch and wash, then pickle and wash, and finally activate with the above-mentioned pretreatment activation solution, and rinse with water after activation. The pretreatment activation solution contains composite antioxidants, which can improve the binding force of aluminum and aluminum alloy surface coatings, and can be directly electroplated after activation.

Description

technical field [0001] The invention belongs to the technical field of activation solution for metal electroplating, and in particular relates to a pretreatment activation solution and a pretreatment method for aluminum and aluminum alloy electroplating. Background technique [0002] Aluminum is a kind of active metal. The surface of aluminum and aluminum alloy can easily react with oxygen and water vapor in the air to form a thin oxide film. This layer of oxide film can lead to weak adhesion between the metal coating and the aluminum substrate. Process requirements. Therefore, aluminum and aluminum alloys must be activated to eliminate oxide films before plating to ensure good adhesion of aluminum and aluminum alloys during plating. [0003] The current aluminum alloy pretreatment process includes the following steps: degreasing→chemical cleaning→zinc dipping→electronic nickel plating→electroless nickel plating, wherein the zinc dipping step is mainly a secondary zinc dipp...

AI Technical Summary

Problems solved by technology

[0003] The current aluminum alloy pretreatment process includes the following steps: degreasing→chemical cleaning→zinc dipping→electronic nickel plating→electroless nickel plating, wherein the zinc dipping step is mainly a secondary zinc dipping process, due to the potential The difference is relatively large, which affects the bonding force and protection of the nickel layer. The zinc layer obtained by two zinc dips will often be dissolved into the plating solution in the subsequent electroless nickel plating, seriously affecting the stability of the plating solution; and after two dips in zinc Occasionally use 1:1 nitric acid for cleaning, which is easy to volatilize into acid mist during the production process, causing great environmental hazards

In addition, the method of dipping zinc twice has many disadvantages: 1. The zinc dipping layer pollutes the electroless nickel plating solution

2. In a humid and corrosive environment, zinc constitutes the anode of the corrosion battery relative to the nickel coating, and the zinc layer will be subjected to lateral corrosion, eventually causing the nickel layer to peel off

3. There is a nitric acid dezincification process between the two zinc immersions, which pollutes the environment

4. The currently developed commercial zinc alloy solution contains cyanide, which is dangerous to operate and does not meet environmental protection requirements.