Metal treatment – Process of modifying or maintaining internal physical... – Processes of coating utilizing a reactive composition which...
Reexamination Certificate
2001-11-21
2003-07-15
Sheehan, John (Department: 1742)
Metal treatment
Process of modifying or maintaining internal physical...
Processes of coating utilizing a reactive composition which...
C148S278000, C148S280000, C148S281000, C148S206000, C427S189000
Reexamination Certificate
active
06592683
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
The present Application claims the benefit of Japanese Patent Application No. 2001-265-461, filed Sep. 3, 2001, the contents of which are incorporated in this disclosure by reference in its entirety.
BACKGROUND OF THE INVENTION
The present invention relates to a method of treating the surface of Ti alloy.
Ti provides high specific strength but is likely to be worn. So surface treatment is required.
To make surface treatment to a Ti alloy poppet valve, there are thermal spray, Ni plating, nitriding in Japanese Patent Laid-Open Pub. No. 61-81505, oxidation in Japanese Patent Laid-Open Pub. Nos. 62-256956 and 3-36257, and plasma carburizing in Japanese Patent No. 2909361.
In thermal spray and plating, to remove an oxide film which is likely to be formed on the surface and to increase adhesion of hard material, the surface of a workpiece must be roughened by shot blasting and pretreated with acid washing to make the process more complicate to increase cost. Hard films are likely to come off.
In nitriding and oxidation, the workpiece is heated, which is relatively simple, but the surface is so hard as to increase offensiveness to an opposite member such as a valve seat and valve guide, which must be replaced in material to increase cost.
In oxidation, a workpiece is heated in oxygen excessive atmosphere to increase oxygen diffusion speed and to form a relatively thick fragile oxide film such as TiO
2
and Ti
2
O
3
, which is likely come off. So the oxide film must be removed by shot blasting or machining until an oxygen diffusion layer appears, thereby increasing cost.
In plasma carburizing, wear resistance required for a poppet valve is available, but it is necessary to provide expensive equipment such as vacuum furnace and plasma electric source to increase depreciation and running cost which causes increased unit price.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method of treating the surface of Ti alloy to increase wear resistance at low cost and simple means.
In order to achieve the object, according to the present invention, there is provided a method of treating the surface of Ti alloy, comprising the steps of embedding the Ti alloy in oxygen-absorptive powder, and heating said Ti alloy with the powder in oxygen atmosphere to diffuse oxygen atoms into the Ti alloy to form an oxygen diffusion layer of Ti—O solid solution.
Without forming an oxide layer on the surface of Ti alloy, a hard oxygen diffusion layer can be formed to provide a wear-resistant Ti alloy.
REFERENCES:
patent: 4936927 (1990-06-01), Grunke et al.
patent: 4940679 (1990-07-01), Claar et al.
patent: 2769852 (1999-04-01), None
Asanuma Hiroaki
Hirose Masahito
Farah David A.
Fuji Oozx Inc.
Oltmans Andrew L.
Sheehan John
Sheldon & Mak PC
LandOfFree
Ti alloy surface treatment does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ti alloy surface treatment, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ti alloy surface treatment will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3008185