Method for coating metallic interconnect of solid oxide fuel cell

Abstract

Disclosed is a method for coating a metallic interconnect for a solid oxide fuel cell (SOFC), the method including the steps of: carrying out pre-treatment for removing impurities adhered on a surface of the metallic interconnect; and carrying out pulse plating with cobalt as an anode, and the metallic interconnect as a cathode, in which an average current density (Ia) is set in a room-temperature cobalt plating solution, and a maximum current density (Ip), a current-on time (Ton) and a current-off time (Toff) are adjusted based on Ia=Ip×Ton / (Ton+Toff). Through the disclosed method, it is possible to obtain a metallic interconnect having a coating surface which has a high electrical conductivity and a high chrome volatilization inhibiting property and can minimize the occurrence of micro-cracks and micro-pores, thereby improving the performance of the SOFC.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a solid oxide fuel cell, and more particularly to a coating method for forming a protective coating on the surface of a metallic interconnect that interconnects unit cells and collects current of a stack.[0003]2. Description of the Prior Art[0004]As power demands show a tendency to gradually increase according to a recent industrial development and economic growth, environmental problems, including air pollution and earth shock, have seriously arisen by the use of fossil fuels (such as petroleum, or coal) required for power production. Especially, since the exhaust of carbon dioxide by the use of fossil fuels is pointed out as a main factor of global warming and various kinds of environmental pollution, the development of solar light / heat energy, bio energy, wind energy, and hydrogen energy, as clean energy sources substituting for the fossil fuels, is being actively conducted.[0005]From...

AI Technical Summary

Benefits of technology

[0015]Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and the present invention provides a method for coating a metallic interconnect for a solid oxide fuel cell (SOFC), which can minimize the occurrence of micro-cracks and micro-pores in a coating layer by formation of densified protective coating.

[0021]Also, after the pulse plating, heat-treatment may be further carried out in a 800° C. reducing atmosphere (10% H2+90% N2) for 2˜20 hours to enhance a binding force between the metallic interconnect and a plated coating layer.

[0022]Through the method according to the present invention, it is possible to obtain a metallic interconnect having a coating surface which has a high electrical conductivity and a high chrome volatilization inhibiting property and can minimize the occurrence of micro-cracks and micro-pores, thereby improving the performance of the SOFC.

Problems solved by technology

As power demands show a tendency to gradually increase according to a recent industrial development and economic growth, environmental problems, including air pollution and earth shock, have seriously arisen by the use of fossil fuels (such as petroleum, or coal) required for power production.

However, by these materials, it is very difficult to achieve the durability of up to 40000 hours required for commercialization, and thus there is need to develop a novel alloy and to research the application of protective coating on the surface of a conventional material.

However, at a higher current density than a predetermined limitation, plating ions around a to-be-coated substrate are depleted by mass transfer limiting conditions, thereby causing concentration polarization.

Accordingly, there is a problem in that a plated surface is non-uniform and a densified coating layer cannot be formed.

Also, in cobalt protective coating using a DC plating method, micro-cracks and micro-pores may be formed within a coating layer due to coarse particles of the coating layer.

Such micro-cracks and micro-pores cause some problems, including peeling of an oxide film on a metallic interconnect surface, and pollution of a cathode, by volatilizing chrome (Cr(IV)) gas from the metallic interconnect during the operation of the SOFC, and thus operates as a factor inhibiting an electrochemical reaction of the SOFC.

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