Method for producing rust-proof member
AssigneeYuken Industry Co., Ltd.
InventorsTsukasa NIWA, Toshihiro SUGIURA, Yoshiki HIRAMATSU, Hiroki YOSHIDA
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Abstract
A reactive chemical conversion treatment liquid capable of forming a Si-containing chemical conversion film is provided. The chemical conversion treatment liquid contains colloidal silica, a trivalent chromium-containing water-soluble substance, and a high pKa organic acid-containing water-soluble substance such as a hydroxymonocarboxylic acid and may further contain a film-formable metal-containing water-soluble substance in a preferred embodiment, and the pH of the chemical conversion treatment liquid is 3.0 or more.
Claims7
A method for producing a rust-proof member, comprising
- a chemical conversion treatment by forming a chemical conversion film on a member to be treated containing zinc on its surface, the chemical conversion treatment comprising bringing a chemical conversion treatment liquid into contact with the member to be treated and then washing the member,
- wherein the chemical conversion treatment liquid comprises:
- colloidal silica,
- a trivalent chromium-containing water-soluble substance that is an ionic substance comprising trivalent chromium, and
- a high pKa organic acid-containing water-soluble substance that is a water-soluble substance comprising a high pKa organic acid that is an organic acid having a lowest pKa of no lower than 3.5,
- the chemical conversion treatment liquid has a pH in a range from 3.0 to 4.5 or less in a state before contacting with the member to be treated, and
- the high pKa organic acid comprises glycolic acid, except for a case that the high pKa organic acid comprises at least one material selected from the group consisting of allylamine, polyallylamine, aromatic sulfonic acid, aromatic sulfonic acid-formaldehyde condensate, and derivatives thereof.
Dependencies are inferred from the claim text.