Methods for manufacturing of cobalt boride coating layer on surface of steels by using a pack cementation process

Patent metadata

Field	Value
Publication number	US-8974857-B2
Application number	US-201213675136-A
Country	US
Kind code	B2
Filing date	Nov 13, 2012
Priority date	Mar 30, 2012
Publication date	Mar 10, 2015
Grant date	Mar 10, 2015

Abstract

Disclosed is to a method for manufacturing a cobalt boride coating layer on the surface of iron-based metals by using a pack cementation process. In particular, the present invention relates to a method for manufacturing a cobalt boride coating layer by forming a composite coating layer on the surface of steels which is composed of an outmost layer having a composition of cobalt boride (Co 2 B) and an inner layer having a composition of iron-cobalt boride ((Fe,Co) 2 B). Since the cobalt boride coating layer is a compact coating layer having little defects such as pores, it can improve physical properties such as corrosion resistance, wear resistance and oxidation resistance of steels.

First claim

What is claimed is:

1. A method for manufacturing a cobalt boride coating layer on the surface of iron-based metals, comprising:
forming a thin layer composed of iron borides on the surface of iron-based metals by using a pack cementation process;
forming a layer composed of cobalt-iron on the surface of iron-based metals by using a pack cementation process on the iron borides; and
forming an outmost layer composed of cobalt boride and an inner layer composed of iron-cobalt boride by using a pack cementation process on the cobalt-iron layer.

2. The method according to claim 1 , which further comprises decreasing the activity of Fe so as to suppress the generation of iron-based gas during the deposition of cobalt using the pack cementation.

3. The method according to claim 1 or 2 , which utilizes a pack powder for cobalt treatment which is composed of 2˜60 wt % of cobalt powder, 1˜10 wt % of NH 4 Cl powder and 30˜97 wt % of Al 2 O 3 powder.

4. The method according to claim 2 , wherein the step of decreasing the activity of Fe is to form an iron boride thin layer.

5. The method according to claim 4 , which utilizes a pack powder for boron treatment which is composed of 1˜50 wt % of B 4 C, 1˜10 wt % of KBF 4 and 40˜98 wt % of SiC.

6. The method according to claim 4 , wherein the iron boride thin layer is formed by boronizing at 600˜1000° C. for 5˜60 min.

7. The method according to claim 1 , wherein the cobalt boride coating layer is formed as an outmost layer composed of Co 2 B and an inner layer composed of (Fe,Co) 2 B.

8. The method according to claim 4 , wherein the iron boride thin layer is formed as a coating layer composed of FeB, Fe 2 B or a mixture thereof.

Assignees

• Korea Inst Sci & Tech

Inventors

• Yoon Jin Kook
• Doh Jung Man
• Park Sang Whan

Classifications

• C23C10/08

  only one element being diffused · CPC title

• C23C8/02 Primary

  Pretreatment of the material to be coated (C23C8/04 takes precedence) · CPC title

• C23C8/80

  After-treatment · CPC title

• C23C8/70

  of ferrous surfaces · CPC title

• C23C10/60

  After-treatment · CPC title