Chromium-free passivation method for active metal

An active metal, chromium-free passivation technology, applied in the field of metal manganese anti-corrosion, can solve problems such as unsatisfactory passivation effect, excessive sulfur content, unqualified products, etc., to improve passivation effect, reduce sulfur content, reduce The effect of drug dosage

Active Publication Date: 2022-01-25
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the above-mentioned chromium-free passivation technology has made progress, it is more or less restricted by problems such as unsatisfactory passivation effect, excessive phosphorus, excessive sulfur, excessive silicon, and poor process matching. It is difficult to replace chromium salt passivation and further Widespread application
In addition, there are also defects such as excessive acid consumption in the passivation process, which may easily cause excessive sulfur content in the product in the metal manganese, and make the product unqualified.
[0004] To sum up, the existing chromium-free passivation technology for active metals such as metal manganese has more or less disadvantages such as unsatisfactory passivation effect, excessive sulfur content in products, and high acid consumption. Therefore, it is urgent to develop new environmentally friendly, Chromium-free passivator product or passivation method with excellent performance

Method used

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  • Chromium-free passivation method for active metal
  • Chromium-free passivation method for active metal
  • Chromium-free passivation method for active metal

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0054] First, an electrolytic manganese product is prepared in a diaphragm tank by electrolysis: stainless steel is used as a cathode plate, and a lead-silver alloy plate is used as an anode plate. Electrolysis conditions: ammonium sulfate 110g / L, manganese sulfate 76.9g / L, selenium dioxide 0.05g / L catholyte, catholyte pH is about 6.8-7.0, current density is 350A / m2, electrolysis temperature is 38°C, prepared Electrolytic manganese product, the prepared electrolytic manganese product is used for subsequent passivation experiment evaluation.

[0055] The passivation steps are:

[0056] Step (1): first use an aerator to aerate the electrolytic manganese in water for 10 minutes. XPS data shows that the Mn element on the surface of the electrolytic manganese is mainly +2 valence, and the +2 valence accounts for more than 90% of the surface.

[0057] Step (2): Passivation

[0058] Put the aluminum-based chromium-free passivator in the passivation tank, the main component of the a...

Embodiment 2

[0096] The production and preparation conditions of the electrolytic manganese metal product are the same as in Example 1. The passivator used in Example 2 is an aluminum-based chromium-free passivator (same as Example 1), the pH of the passivation solution is 3.5-4.0, and the passivation time is 2.0 min. Continuous production of electrolytic manganese, monitoring of acid consumption during passivation. The test shows that after the electrolytic manganese is produced out of the tank, the electrolytic manganese is first strengthened with an aerator for 10 minutes, then passivated with an aluminum-based chromium-free passivation solution for 2.0 minutes, taken out, and dried to obtain a passivated metal manganese product. According to this technical scheme, for every ton of electrolytic manganese produced, the passivation acid consumption is about 0.18Kg98%H 2 SO 4 . The Mn content of electrolytic manganese products is >99.9%, and the S content is 0.013%. The electrochemical...

Embodiment 3

[0102] The production and preparation conditions of the electrolytic manganese metal product are the same as in Example 1. The passivator used in Example 3 is an aluminum-based chromium-free passivator (same as Example 1), the pH of the passivation solution is 3.5-4.0, and the passivation time is 2.0 min. Continuous production of electrolytic manganese, monitoring of acid consumption during passivation. The test shows that after the electrolytic manganese is produced out of the tank, the electrolytic manganese is first strengthened with an aerator for 3.0 minutes, then passivated with an aluminum-based chromium-free passivation solution for 2.0 minutes, taken out, and dried to obtain passivated metal manganese products . According to this technical scheme, for every ton of electrolytic manganese produced, the passivation acid consumption is about 0.26Kg98%H 2 SO 4 . The Mn content of electrolytic manganese products is >99.9%, and the S content is 0.018%. The electrochemic...

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Abstract

The invention relates to the field of corrosion prevention of metal manganese, and particularly discloses a chromium-free passivation method for active metal. The method comprises the following steps that (1) surface oxidation is carried out on active metal to be treated in a gas-solid-liquid three-phase system, and a surface layer containing a hydrate of metal M is formed on the surface of the active metal in situ; and (2) the active metal subjected to surface oxidation is placed in a chromium-free passivating agent dissolved with metal N ions, passivating treatment is carried out, and a surface oxidation layer is converted into an M-N double-metal passivation layer. According to the technical means, on the basis of the special surface oxidation mode and the interface conversion passivation mode, in-situ formation of the passivation layer on the active metal surface is achieved by utilizing a brand new mechanism of in-situ interface reaction of in-situ compounded hydrates and oxides on the surface of the base metal and matched metal ions in the passivating agent.

Description

technical field [0001] The invention relates to the field of metal manganese anticorrosion, in particular to a chromium-free passivation method. Background technique [0002] Active metals such as metal zinc, metal aluminum, metal manganese, etc. as important metal elements are widely used in industry and have a large demand. They have very important strategic significance for the development of the national economy. They are used in iron and steel smelting, construction, machinery and transportation There are applications in various industries. However, active metals such as electrolytic manganese are very active metals. If they are directly exposed to the air, they are easily oxidized into brown or black metal oxides, thereby greatly reducing the purity and commercial value of manganese products. Therefore, in the current production of electrolytic manganese, metal zinc (or zinc alloy), aluminum (or aluminum alloy) and other metals, potassium dichromate is widely used for...

Claims

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Application Information

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IPC IPC(8): C23C22/73C23C22/06C23C22/58
CPCC23C22/73C23C22/06C23C22/58Y02P10/20
Inventor 曹占芳钟宏
Owner CENT SOUTH UNIV
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