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US 4,072,588 AGranted
Method for the anodic polishing of surfaces of intermetallic niobium compounds and niobium alloys
AssigneeSiemens Aktiengesellschaft
InventorHeinrich Diepers
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Abstract
The surface of an intermetallic niobium compound or niobium alloy to be polished is electrically shunted across a niobium part and immersed in electrolyte together with the latter permitting relatively thick surface layers of niobium compounds of high quality which are used for superconducting a-c apparatus to be produced.
Claims4
A method for the anodic polishing of surfaces of intermetallic niobium compounds and niobium alloys comprising:
- a. placing a niobium part as an anode and a cathode, in an electrolyte consisting of 86 to 93% by weight H.sub.2 SO.sub.4, 1.5 to 4% by weight HF and 5.5 to 10.0% by weight H.sub.2 O with a temperature of between 15.degree. and 50.degree. C;
- b. electrically shunting the surface to be polished across the niobium part;
- c. adjusting a constant voltage of between 9 and 15 V between the niobium part and the cathode in such a manner that damped current oscillations are superimposed on the electrolyte current;
- d. switching off the voltage at the latest after the current oscillations have decayed completely, and keeping it off until the oxide layer built up during the current oscillations is dissolved;
- e. subsequently again adjusting a constant voltage between 9 and 15 V so that damped current oscillations occur;
- and,
- f. repeating the sequence of states with the voltage switched on and off several more times.
4 more elements
Dependencies are inferred from the claim text.