Surface treatment method and coating method for steel material, and method for producing machine component

Patent metadata

Field	Value
Publication number	US-9752225-B2
Application number	US-201214350724-A
Country	US
Kind code	B2
Filing date	Sep 12, 2012
Priority date	Oct 25, 2011
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

This surface treatment method comprises a rustproofing step, a rinsing step, and a cleaning step. In the rustproofing step, a rustproofing liquid containing orthophosphoric acid and an organic acid is used to perform a rustproofing treatment on the surface of a steel material. In the rinsing step, a treatment liquid containing an oxo acid salt of a transition metal is used to perform a rinsing treatment on the surface of the steel material. In the cleaning step, the surface of the steel material that has undergone the rinsing step is subjected to a cleaning treatment.

First claim

The invention claimed is:

1. A surface treatment method for a steel material, comprising:
a rustproofing step of using a rustproofing liquid containing orthophosphoric acid and an organic acid to perform a rustproofing treatment on a surface of a steel material;
a rinsing step of using a treatment liquid containing an oxo acid salt of a transition metal to perform a rinsing treatment on the surface of the steel material; and
a cleaning step of subjecting the surface of the steel material that has undergone the rinsing step to a cleaning treatment,
the treatment liquid used in the rinsing step consisting of an oxo acid salt of a transition metal and water having an electrical conductivity of 20 μS or less.

2. The surface treatment method for a steel material according to claim 1 , further comprising
a degreasing step of using a degreasing liquid to remove oil and grease from the surface of the steel material.

3. The surface treatment method for a steel material according to claim 2 , further comprising
a first water washing step of washing the surface of the steel material that has undergone the degreasing step.

4. The surface treatment method for a steel material according to claim 3 , wherein
the first water washing step is repeated a plurality of times.

5. The surface treatment method for a steel material according to claim 1 , further comprising
a second water washing step of using a treatment liquid containing orthophosphoric acid and an organic acid to wash the surface of the steel material that has undergone the rustproofing step.

6. The surface treatment method for a steel material according to claim 5 , wherein
the treatment liquids used in the rustproofing step and the second water washing step contain sodium dihydrogen phosphate dihydrate, a fluorine-based surfactant, and water having an electrical conductivity of 20 μS or less.

7. The surface treatment method for a steel material according to claim 5 , wherein
ultrasonic waves or a spray is used in the second water washing step.

8. The surface treatment method for a steel material according to claim 1 , further comprising
a spray step of spraying water on the surface of the steel material that has undergone the cleaning step.

9. The surface treatment method for a steel material according to claim 1 , wherein
the oxo acid salt of a transition metal contained in the treatment liquid used in the rinsing step is either a tungstate, a molybdate, or a zirconate.

10. The surface treatment method for a steel material according to claim 1 , wherein
rustproofing of the steel material and a phosphate coating treatment are carried out simultaneously in the rustproofing step.

11. The surface treatment method for a steel material according to claim 1 , further comprising
a coating step of subjecting the steel material to a coating treatment.

12. The surface treatment method for a steel material according to claim 11 , further comprising
producing a machine component with the steel material following the coating step.

13. The surface treatment method for steel material according to claim 12 , wherein
the machine component is a hydraulic line for a hydraulic excavator.

Assignees

• Morita Haruji
• Tate Tsuneo
• Shiozawa Akira
• Komatsu Mfg Co Ltd
• Cotec Corp
• Nippon Kazai Co Ltd

Inventors

• Morita Haruji
• Tate Tsuneo
• Shiozawa Akira

Classifications

• C23C22/83 Primary

  Chemical after-treatment · CPC title

• C23C8/42 Primary

  only one element being applied · CPC title

• C23C22/47

  containing also phosphates · CPC title

• C23C22/08 Primary

  Orthophosphates · CPC title

• C23C8/80

  After-treatment · CPC title