Metallische bipolare Platte für HT-Brennstoffzellen und Verfahren zur Herstellung desselben

摘要

Described are bipolar metallic plates, made of a chromium-oxide-forming alloy, for high-temperature fuel cells. In the zone of their gas-conducting surfaces, the plates have aluminium-enriched surface layers preferably 20 to 200 mu m stick, in particular 50 to 100 mu m thick. Preferred chromium-oxide-forming alloys are Cr, Cr-Ni and Cr-Fe alloys, particularly a chromium-based alloy such as Cr-5Fe-1Y2O3 or an iron-based alloy such as ferritic steel containing 20 to 35 % by wt. of Cr. The surface of the bipolar plate includes channels (4) separated from each other by lands (2) which are in contact with the electrode, the gas-conducting surfaces (3) of the channels having aluminium-enriched layers. To manufacture such bipolar plates, the surface of the prefabricated plate is enriched in aluminium to the required depth, preferably by alitizing, and the aluminium-enriched layer subsequently removed from the electrode-contacting surfaces, preferably by grinding.