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CN-117684159-B - Stainless steel passivation solution and preparation method and application thereof

CN117684159BCN 117684159 BCN117684159 BCN 117684159BCN-117684159-B

Abstract

The invention relates to the technical field of surface treatment, and provides stainless steel passivation solution, a preparation method and application thereof, wherein the passivation solution comprises an oxidant and rare earth metal salt; the oxidant is used for forming metal oxide on the surface of the stainless steel, the rare earth metal salt is used for forming rare earth metal compound on the surface of the stainless steel, and the metal oxide and the rare earth metal compound jointly form a passivation film on the surface of the stainless steel. The passivation solution orderly forms a passivation film with a compact structure on the surface of stainless steel, and the passivation film has excellent corrosion resistance, and is remarkably improved under test environments such as salt fog, pitting corrosion, corrosion current, boiled brine and the like compared with the main flow of the passivation solution on the market by adopting a silane+resin passivation scheme.

Inventors

  • HONG FANG
  • ZHOU BINGKUN
  • HUANG KAI
  • ZHAO HU
  • FU TAO

Assignees

  • 广东美的制冷设备有限公司
  • 美的集团股份有限公司

Dates

Publication Date
20260505
Application Date
20231211

Claims (12)

  1. 1. The stainless steel passivation solution is characterized by comprising an oxidant and rare earth metal salt, wherein the oxidant is used for forming metal oxide on the surface of stainless steel, the rare earth metal salt is used for forming rare earth metal compound on the surface of stainless steel, and the metal oxide and the rare earth metal compound form a stainless steel surface passivation film together; comprises the following components in percentage by mass: 1-20% of an oxidant, wherein the oxidant is hydrogen peroxide; 1-20% of an oxidant stabilizer, wherein the oxidant stabilizer is sodium fatty acid; 1-10% of complexing agent, wherein the complexing agent comprises more than one of sodium gluconate, sodium citrate and EDTA disodium salt; 1-5% of a surfactant, wherein the surfactant comprises more than one of nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, high-carbon fatty alcohol polyoxyethylene ether and sodium dodecyl sulfonate; 1-10% of corrosion inhibitor, wherein the corrosion inhibitor comprises more than one of D-sodium gluconate, urotropine, gallic acid, silicate, molybdate, tungstate and polyphosphate; 1-10% of rare earth metal salt, wherein the rare earth metal salt comprises metal cerium salt; 1-5% of chelating agent, wherein the chelating agent comprises more than one of phytic acid, triphenylring imidazoline quaternary ammonium salt, hydroxyethylidene diphosphate, polyhydroxy polymeric organic acid sodium salt and ethylenediamine di-o-hydroxyphenyl sodium iron acetate; 1-5% of penetrating agent, wherein the penetrating agent is more than one of fatty alcohol polyoxyethylene ether, fatty alcohol, organic siloxane and ethylenediamine EO-PO; the pH value of the passivation solution is 6-7.
  2. 2. The stainless steel passivation solution according to claim 1, wherein the mass ratio of the oxidizing agent to the rare earth metal salt is (1-20): 1-10.
  3. 3. The stainless steel passivating solution according to claim 1 or 2, wherein the complexing agent is disodium EDTA; the surfactant is sodium dodecyl sulfonate; The corrosion inhibitor is sodium molybdate; the rare earth metal salt is cerium nitrate; The chelating agent is phytic acid; The penetrating agent is fatty alcohol polyoxyethylene ether.
  4. 4. The stainless steel passivation solution according to claim 3, wherein the stainless steel passivation solution comprises, by mass, 5-20% of hydrogen peroxide, 5-20% of sodium fatty acid, 1-8% of EDTA disodium salt, 1-8% of sodium dodecyl sulfate, 1-8% of sodium molybdate, 1-8% of cerium nitrate, 2-4% of phytic acid, 1-4% of fatty alcohol polyoxyethylene ether and the balance of water.
  5. 5. The stainless steel passivation solution according to claim 4, wherein the stainless steel passivation solution comprises, by mass, 10-20% of hydrogen peroxide, 10-20% of sodium fatty acid, 2-8% of EDTA disodium salt, 2-8% of sodium dodecyl sulfate, 1-6% of sodium molybdate, 1-5% of cerium nitrate, 3-5% of phytic acid, 1-3% of fatty alcohol polyoxyethylene ether and the balance of water.
  6. 6. The use of the passivation solution according to any one of claims 1 to 5 in stainless steel.
  7. 7. The method of claim 6, wherein the forming comprises forming a passivation film consisting essentially of a metal oxide and a rare earth metal compound on the surface of the stainless steel.
  8. 8. The use according to claim 7, wherein the use comprises in situ formation of a metal oxide layer on the stainless steel surface, and the rare earth metal compound forms a rare earth metal compound precipitate on the metal oxide layer.
  9. 9. The use according to claim 8, wherein the use comprises adsorption of the phytic acid on the surface of the rare earth metal compound precipitate for forming an adsorption film for improving the corrosion resistance of stainless steel.
  10. 10. The use according to claim 6, wherein the stainless steel is a stainless steel having a nickel content of less than 9%.
  11. 11. The use of claim 6, wherein the stainless steel is 430 stainless steel.
  12. 12. A method for passivating stainless steel, which is characterized by comprising the step of passivating the surface of the stainless steel by the passivating solution according to any one of claims 1-5.

Description

Stainless steel passivation solution and preparation method and application thereof Technical Field The invention relates to the technical field of surface treatment, relates to stainless steel passivation solution and a preparation method and application thereof, and in particular relates to chromium-free passivation solution for low-Ni stainless steel and a preparation method and application thereof. Background Stainless steel is widely used in household appliances and kitchen appliances, and 304 stainless steel can meet most scene demands, but 304 stainless steel has high cost, and is mainly because of containing a large amount of rare element Ni. The current technical innovation is to develop stainless steel with low Ni content and high corrosion resistance, or to adopt low Ni stainless steel and passivation technology to meet the corrosion resistance requirement. There are many passivation techniques for stainless steel, and the following general classes have been used in many cases: (1) Hexavalent chromium passivation scheme. According to the scheme, a compact passivation film can be formed on the surface of the stainless steel, the corrosion resistance can be greatly improved, and even if the surface is scratched, hexavalent chromium in the film layer can repair the passivation film, and the corrosion resistance is still maintained. Hexavalent chromium is a highly toxic carcinogen, and with the importance of human beings on the environment and health, it has been increasingly prohibited by countries around the world. (2) Trivalent chromium passivation scheme. Similar to hexavalent chromium, the principle is that a compact passivation film is generated on the surface of stainless steel, and trivalent chromium can not cause cancer directly, but is possibly oxidized into hexavalent chromium, and serious risks still exist. In recent years, chromium-free passivation solutions have been developed by many enterprises and units in order to solve environmental and health problems. According to the patent application CN113430507A, a chromium-free stainless steel passivating agent is disclosed, and comprises, by weight, 10-15 parts of rare earth metal salt, 3-5 parts of organic acid, 8-10 parts of silane coupling agent, 3-5 parts of complexing agent, 3-5 parts of film curing agent, 3-5 parts of accelerator, 2-3 parts of water-soluble titanium oxide and the balance deionized water. However, the silane coupling agent in this solution is liable to lose its function in a relatively high-temperature and humid environment. For another example, patent CN102168265B discloses a chromium-free composite passivating agent and a preparation method thereof. The paint comprises, by mass, 3.0-10% of gamma-methacryloxy trimethoxy silane, 0.1-3.0% of sodium molybdate, 0.1-5.0% of cerium chloride, 0.5-4.0% of phosphoric acid, 0.5-4.0% of acetic acid, 15-20% of water-soluble epoxy resin, 5-15% of water-soluble acrylic resin, 10-30% of water and 20-40% of ethanol. In the scheme, gamma-methacryloxy trimethoxy silane is relatively complex, so that powder is very easy to hang when a product is passivated, and the popularization and application of the product are greatly limited by using a large amount of ethanol. For another example, patent CN101717930B discloses a passivating agent formulation comprising (a) 5-50 ml of class a alkoxysilane, alkoxysilane containing at least one epoxy functional group, or alkoxysilane containing at least one amino functional group, alkoxysilane containing an epoxy functional group, (B) 5-50 ml of class B alkoxysilane, disilyl silane containing at least one non-hydrophilic functional group, (c) water-dispersible nanosilicon dioxide in an amount of 5-200 mg/l, (d) nanosilicon dioxide in an amount of 0-200 mg/l, (e) rare earth cerium salt in an amount of 10-500 mg/l, (f) water balance, containing a small amount of acetic acid and ethanol. The scheme aims to form a silane coating on the surface of the treated metal, wherein the silane coating has excellent corrosion resistance, and can prolong the service life of the metal to a certain extent, but the silane is unstable and easy to hydrolyze with water, and the adopted water-dispersible nano silicon dioxide has extremely high requirements on the nano silicon dioxide and storage environment and is easy to agglomerate. In view of this, the present invention has been proposed. Disclosure of Invention The invention provides stainless steel passivating solution, a preparation method and application thereof, which are used for solving the defect of insufficient corrosion resistance of a chromium-free passivating agent for low-Ni stainless steel in the prior art. The stainless steel passivation solution comprises an oxidant and rare earth metal salt, wherein the oxidant is used for forming metal oxide on the surface of stainless steel, the rare earth metal salt is used for forming rare earth metal compound on the surface of stainless steel, and the metal oxide an