Passivating treatment method for stainless steel rare earth conversion coatings

A passivation treatment and rare earth conversion technology, applied in the direction of metal material coating process, etc., can solve the problems of waste water pollution to the environment, health hazards of workers, and high toxicity.

Inactive Publication Date: 2012-07-18
SHANGHAI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At the same time, nitric acid, hydrofluoric acid and chromate are highly toxic, and the aerosol generated during the passivation process is a serious hazard to the health of workers, and the discharged wastewater seriously pollutes the environment

Method used

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  • Passivating treatment method for stainless steel rare earth conversion coatings
  • Passivating treatment method for stainless steel rare earth conversion coatings
  • Passivating treatment method for stainless steel rare earth conversion coatings

Examples

Experimental program
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Effect test

Embodiment 1

[0016] Surface treatment and polarization curve test of 316L stainless steel at 55°C

[0017] The 316L stainless steel is treated according to the steps described in the content of the invention: mechanically polish a 20mm×10mm×5mm 316L stainless steel sample to clean the surface and remove oil stains; the passivation temperature is controlled at 55°C, and 0.023mol / L cerium nitrate is added to the passivation solution and citric acid with a mass fraction of 0.4%, and distilled water and hydrogen peroxide (with a mass fraction of 30% hydrogen peroxide) at a volume ratio of 1:1, and treat for a certain period of time until the surface color of the sample turns golden yellow to obtain a uniform rare earth conversion coating; then Take out the sample, wash it with deionized water, put it into a desiccator at room temperature and wait for it to dry completely, and get a dense rare earth oxide film on the stainless steel surface. Seal the non-working surface with epoxy resin, leavin...

Embodiment 2

[0019] Surface treatment and polarization curve test of 316L stainless steel at 70°C

[0020] The 316L stainless steel is treated according to the steps described in the content of the invention: mechanically polish a 20mm×10mm×5mm 316L stainless steel sample to clean the surface and remove oil stains; the passivation temperature is controlled at 70°C, and 0.023mol / L cerium nitrate is added to the passivation solution and citric acid with a mass fraction of 0.5%, and distilled water and hydrogen peroxide (30% hydrogen peroxide) in a volume ratio of 1:1, and treat for a certain period of time until the surface color of the sample turns golden yellow to obtain a uniform rare earth conversion coating; then Take out the sample, wash it with deionized water, put it into a desiccator at room temperature and wait for it to dry completely, and get a dense rare earth oxide film on the stainless steel surface. Seal the non-working surface with epoxy resin, leaving only the surface of 15...

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Abstract

The invention belongs to the technical field of stainless steel surface treatment, and particularly relates to a passivating treatment method for stainless steel rare earth conversion coatings, which comprises the steps of soaking a stainless steel sample in a passivation solution of cerous nitrate, hydrogen peroxide and citric acid with proper concentration to be treated within a low temperature range, judging passivation time through changes of matrix surface colors, and then fetching out the sample to be cooled and dried so as to obtain a compact, smooth and golden rare earth oxide film on the stainless steel surface. The concentration of cerous nitrate is 0.01-0.05 mol/L, the volume fraction of hydrogen peroxide with 30% of mass fraction is 30-70%, and the mass fraction of citric acid is 0.1-4%. The passivation treatment temperature is 20-75 DEG C. The method can effectively improve pitting corrosion resistance and has important value.

Description

technical field [0001] The invention belongs to the technical field of stainless steel surface treatment, and relates to the passivation treatment of stainless steel surface by using chemical methods, in particular to a process method for carrying out passivation treatment of stainless steel by using cerium nitrate, hydrogen peroxide and citric acid as main components of passivation liquid. Background technique [0002] Stainless steel surface passivation treatment is to form a thin, dense, good coverage and strong adhesion oxide film on the metal surface by chemical treatment to block or slow down the infiltration and diffusion of external corrosive media, so as to achieve An effective way to slow down the corrosion rate of stainless steel. Due to its high corrosion resistance, stainless steel is widely used in industrial fields, but these stainless steel materials have a tendency to pitting corrosion, usually in the presence of reducing agents or due to medium temperature ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C22/73C23C22/50
Inventor 李谋成徐健辛森森
Owner SHANGHAI UNIV
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