Chrome-free passivation solution for copper plated pieces and passivating treatment method thereof

Abstract

The invention discloses a chrome-free passivation solution for copper plated pieces and a passivating treatment method thereof. According to the defects that passivation pollution of hexavalent chromium is serious, the dropping time of nitric acid with the volume ratio being 1:1 is short in an existing chrome-free passivation technology and passivation solution cost is high, the chrome-free passivation solution comprises sulfuric acid with the concentration being 140-180ml / L, oxalic acid dihydrate with the concentration being 7-10g / L, 85% phosphoric acid with the concentration being 100-130ml / L, a corrosion inhibitor with the concentration being 2-10g / L, polyethylene glycol with the concentration being 2-5g / L and 30% hydrogen peroxide with the concentration being 7-10ml / L. Confining liquidcomprises a corrosion inhibitor with the concentration being 2-10g / L, absolute ethyl alcohol with the concentration being 4-10ml / L, sodium phorhoate tribaric dodecahydrate with the concentration being 2-6g / L, glycerin with the concentration being 2-4ml / L, 2-mercaptobenzothiazole with the concentration being 0.01-0.1g / L and a surface active agent. The surface active agent can be either fatty alcohol-polyoxyethylene ether with the concentration being 0.3-1g / L or alkylphenol polyoxyethylene with the concentration being 0.5-3ml / L. The corrosion inhibitor can be one of benzotriazole, N-methyl benzotriazole, N-ethyl benzotriazole and N-propyl benzotriazole. The passivation technology is simple, operation is easy, controllability is good, and the applied range is wide. Moreover, the corrosion resistance to the nitric acid with the volume ratio being 1:1 of the specimen treated through the passivation method is excellent and the requirements for aviation standard HB-5064 are met.

Description

technical field [0001] The invention belongs to the technical field of metal material surfaces, and in particular relates to a chromium-free passivation solution for copper plating parts and a passivation treatment method thereof. Background technique [0002] In a humid environment, the surface of copper-plated parts is prone to discoloration and corrosion, especially for parts and mechanism components with strict size requirements, the problem is particularly serious. At present, in order to prevent discoloration and performance degradation caused by oxidation on the surface of copper-plated parts, the passivation process of chromic anhydride and chromate is generally used in the aviation industry. The quality of its passivation process is tested according to HB5064, that is, the nitric acid with a volume ratio of 1:1 is used for a drop test to observe the time required for the formation of bubbles. Using chromic anhydride and chromate passivation treatment, although the ...

AI Technical Summary

Problems solved by technology

Using chromic anhydride and chromate passivation treatment, although the corrosion resistance of the copper plating layer is greatly improved, but because the passivation process contains highly toxic hexavalent chromium, it will seriously endanger the health of operators and cause large environmental pollution.

However, the ordinary BTA passivation process is not resistant to the corrosion of strong oxidizing acid, and it is difficult to meet the requirements of aviation manufacturing.