Surface treatment method of titanium material for electrodes

Abstract

Disclosed herein is a surface treatment method of a titanium material for electrodes characterized by including: a titanium oxide layer formation step S1 of forming a titanium oxide layer with a thickness of 10 nm or more and 80 nm or less on the surface of a titanium material including pure titanium or a titanium alloy; a noble metal layer formation step S2 of forming a noble metal layer with a thickness of 2 nm or more including at least one noble metal selected from Au, Pt, and Pd on the titanium oxide layer by a PVD method; and a heat treatment step S3 of heat treating the titanium material having the noble metal layer formed thereon at a temperature of 300° C. or more and 800° C. or less.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a titanium material for electrodes. More particularly, it relates to a surface treatment method of a titanium material for an electrode suitable for a separator made of titanium for a fuel cell.[0003]2. Description of the Related Art[0004]As distinct from the primary cell of a dry cell or the like, and the secondary cell of a lead storage battery or the like, the fuel cell capable of continuously extracting electric power by continuing supplying a fuel such as hydrogen and an oxidant such as oxygen is high in electric power generation efficiency, is not largely affected by the size of the system scale, and makes less noise and vibration. For this reason, the fuel cell is expected as an energy source covering various uses / scales. Then, the fuel cells have been developed as, specifically, a polymer electrolyte fuel cell (PEFC), an alkaline electrolyte fuel cell (AFC), a phosphoric acid fue...

AI Technical Summary

Benefits of technology

[0016]The present inventors conducted a close study in order to solve the foregoing problem. As a result, they found out that surface treatment of a titanium material under prescribed conditions improves the electrical conductivity, the corrosion resistance, and the hydrogen absorption resistance. This has led to the completion of the present invention.

[0018]Thus, by forming the titanium oxide layer with a specific thickness on the surface of the titanium material in the titanium oxide layer formation step, it is possible to improve the hydrogen absorption resistance. Then, by forming the noble metal layer in the noble metal layer formation step, it is possible to improve the electrical conductivity while improving the corrosion resistance. Further, by the heat treatment in the heat treatment step, the noble metal layer is improved in adhesion, and becomes less likely to be peeled off. Further, a part of oxygen in the titanium oxide layer is diffused into the titanium material, resulting in an oxygen deficiency type titanium oxide layer. This can still further improve the electrical conductivity.

[0022]For this reason, for example, when a separator for a fuel cell is manufactured by using a titanium material for electrodes, which has been surface treated with the surface treatment method of a titanium material for electrodes of the present invention, and used for a fuel cell, the effects of being capable of keeping excellent electrical conductivity, corrosion resistance, and hydrogen absorption resistance for a long period are produced.

Problems solved by technology

Further, a part of oxygen in the titanium oxide layer is diffused into the titanium material, resulting in an oxygen deficiency type titanium oxide layer.

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