# US 5,344,505 A · Non-chromium passivation method and composition for galvanized metal surfaces

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- Number: US 5,344,505 A
- Document ID: US5344505A
- Status: Granted
- Kind: A
- Application number: 08/107,383
- Filed: 1993-08-16
- Granted: 1994-09-06
- Earliest claimed: 1993-08-16
- Assignees: Betz Laboratories, Inc.
- Inventors: Jiangbo Ouyang; William L. Harpel
- Web page: https://patentgrep.com/patent/US5344505A

## CPC

- C23C 22/08: Orthophosphates
- C23C 22/42: containing also phosphates
- C23C 22/74: for obtaining burned-in conversion coatings
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)

## Abstract

A substantially chromium free composition and method for passivating a galvanized metal surface is disclosed. The passivation treatment which may be rinsed or dried-in-place includes phosphoric acid, boric acid and optionally molybdic acid.

## Claims

### Claim 1

A process for passivating a galvanized metal surface comprising contacting the galvanized surface with an aqueous, substantially chromium free, treatment solution consisting essentially of from about 0.5 to 50% phosphoric acid, and from about 0.1 to 5% boric acid.

### Claim 2 (depends on 1)

The process of claim 1 wherein said treatment solution is baked on said galvanized metal at temperatures of up to about 300.degree. C.

### Claim 3 (depends on 1)

The process of claim 1 wherein said treatment solution further includes from about 0.1 to 0.5% molybdic acid.

### Claim 4

A passivation treatment solution for galvanized metal consisting essentially of from about 0.5 to 5% phosphoric acid, from about 0.1 to 5% boric acid and from 0 to 0.5% molybdic acid wherein said treatment solution is substantially free of chromium.

### Claim 5

A composition for passivating a galvanized metal surface consisting essentially of from about 0.5 to 50% phosphoric acid, from about 0.1 to 5% boric acid and from 0 to about 0.5% molybdic acid.

### Claim 6

A process for passivating a galvanized metal surface comprising contacting the galvanized surface with an aqueous, substantially chromium free, treatment solution consisting essentially of from about 0.5 to 50% phosphoric acid, from about 0.1 to 5% boric acid, and from about 0.1 to 0.5% molybdic acid.