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High corrosion resistance passivation solution for zinc alloy die castings and passivation method

A die-casting and zinc alloy technology, which is applied in the field of high corrosion-resistant passivation solution and its preparation, and the passivation field of zinc alloy die-castings, which can solve the problems of relatively large fluctuations in corrosion resistance data, low corrosion resistance data, and passivation time. Long and other problems, to achieve the effect of improving passivation quality, short passivation time, and good conductivity

Inactive Publication Date: 2014-11-12
SHENZHEN XINMINGDA ENVIRONMENTAL PROTECTION SCI & TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the corrosion resistance data fluctuates greatly, which may lead to large fluctuations in quality during industrial production, and the corrosion resistance data is not high, and the passivation time is too long, so there is still a gap in meeting the actual needs of industrialization

Method used

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  • High corrosion resistance passivation solution for zinc alloy die castings and passivation method

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Experimental program
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Effect test

Embodiment 1

[0038] A high corrosion-resistant passivation solution for zinc alloy die castings, comprising the following components (by mass percentage): Cr 2 (SO 4 ) 3 ·6H 2 O 5%, K 2 ZrF 6 3%, mixed additives 0.5%, polyethylene glycol 0.01%, and the balance is water. Wherein, the mixing accelerator is a mixture of cerium nitrate hexahydrate, ammonium bifluoride and sodium nitrate in a mass ratio of 1:1:5.

[0039] At room temperature and pressure, the Cr 2 (SO 4 ) 3 ·6H 2 Dissolve O in appropriate amount of water, add K while stirring 2 ZrF 6 And mixing accelerator, continue to stir to make it completely dissolved; then add polyethylene glycol, stir evenly; finally add the remaining water, that is.

[0040] Passivation process:

[0041] (1) Pre-degrease the partially oxidized zinc alloy die casting with a degreasing agent, degrease at a temperature of 50-70°C for 10-20 minutes, or ultrasonically degrease for 5-10 minutes at room temperature;

[0042] (2) Wash away excess de...

Embodiment 2

[0051] A high corrosion-resistant passivation solution for zinc alloy die castings, comprising the following components (by mass percentage): Cr 2 (SO 4 ) 3 ·6H 2 O 7%, K 2 ZrF 6 5%, mixed additives 1.5%, polyethylene glycol 0.03%, and the balance is water. Wherein, the mixing accelerator is a mixture of cerium nitrate hexahydrate, ammonium bifluoride and sodium nitrate in a mass ratio of 1:1:5.

[0052] At room temperature and pressure, the Cr 2 (SO 4 ) 3 ·6H 2 Dissolve O in appropriate amount of water, add K while stirring 2 ZrF 6 And mixing accelerator, continue to stir to make it completely dissolved; then add polyethylene glycol, stir evenly; finally add the remaining water, that is.

[0053] Prepare the above-mentioned prepared solution into 10% working solution, heat to 35°C, adjust the pH value to 3.8 with 1% sulfuric acid or sodium hydroxide, and passivate the zinc alloy die casting according to the passivation process in Example 1. Chemical treatment, pas...

Embodiment 3

[0056] A high corrosion-resistant passivation solution for zinc alloy die castings, comprising the following components (by mass percentage): Cr 2 (SO 4 ) 3 ·6H 2 O 5%, K 2 ZrF 6 3%, mixed additives 1.0%, polyethylene glycol 0.02%, and the balance is water. Wherein, the mixing accelerator is a mixture of cerium nitrate hexahydrate, ammonium bifluoride and sodium nitrate in a mass ratio of 1:1:5.

[0057] At room temperature and pressure, the Cr 2 (SO 4 ) 3 ·6H 2 Dissolve O in appropriate amount of water, add K while stirring 2 ZrF 6 And mixing accelerator, continue to stir to make it completely dissolved; then add polyethylene glycol, stir evenly; finally add the remaining water, that is.

[0058] Prepare the above-mentioned prepared solution into 10% working solution, heat to 35°C, adjust the pH value to 3.8 with 1% sulfuric acid or sodium hydroxide, and passivate the zinc alloy die casting according to the passivation process in Example 1. Chemical treatment, pas...

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Abstract

The invention provides a high corrosion resistance passivation solution for zinc alloy die castings and a passivation method. The high corrosion resistance passivation solution comprises 1% to 10% of chromic salts, 1% to 8% of rare earth compounds, 0.1% to 5% of mixed accelerant, 0.01% to 0.05% of surface active agents and the balance water. The mixed accelerant is a mixture of cerous nitrate, ammonium bifluoride and sodium nitrate, wherein the mass ratio of the cerous nitrate to the ammonium bifluoride to the sodium nitrate is (0.5-2):(0.5-2):(3-8). The cleaned zinc alloy die castings are immersed into a working solution prepared by the high corrosion resistance passivation solution to be passivated, cleaned and dried. According to the high corrosion resistance passivation solution, the components are synergized by optimizing the component formula ratio, the passivation time is short, a passivation film layer is dark blue and is uniform, compact and high in corrosion resistance, no corrosion exists in a salt spray test 168H, the electrical conductivity of the film layer is good, the zinc alloy die castings with the oxidized surfaces can be treated, the passivation quality of non-fresh zinc alloy workblanks is greatly improved, and the requirement for industrial production is met.

Description

technical field [0001] The invention belongs to the technical field of metal surface treatment and anticorrosion, and in particular relates to a highly corrosion-resistant passivation solution for zinc alloy die castings and a preparation method thereof, and a passivation method for zinc alloy die castings. Background technique [0002] Passivation is a relatively low-cost processing method for zinc alloy die-casting parts, and it is widely used in the fields of pre-spraying treatment and post-galvanizing treatment. Traditional hexavalent chromium passivation can form a corrosion-resistant dense passivation film, but since hexavalent chromium has been banned by the European Union's RoHS directive and various environmental regulations in other regions, non-hexavalent chromium passivation technology has gained improve dramatically. Due to poor corrosion resistance and high cost of chromium-free passivation technology, it is difficult to gain market acceptance. The mainstream...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C22/34C23C22/78
Inventor 刘彦明
Owner SHENZHEN XINMINGDA ENVIRONMENTAL PROTECTION SCI & TECH CO LTD
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