![]() ![]() This has come about with the recognition that metals that are highly pure often have properties that are different- sometimes predictably different and predictably more useful- from those they have in the ordinary state. In the past few years industrial and governmental research organizations have undertaken many studies for the development of methods for producing many metals in the purest state possible. The average metal-to-salts weight ratio of deposits removed from the cell was 2.4 to 1. were normal, but excessively large deposits, or deposits of extremely large crystals, were usually in part lost to the bath, with the result that current efficiencies apparently as low as 55 pct. This small difference between materials with large differences in oxygen and nitrogen contents, plus some lack in reproducibility of results, leads to the conclusion that the present method of hardness testing does not affort an index to the oxygen and nitrogen content of chromium metal.Ĭurrent efficiencies of 90 pct. The average hardness of the feeds was 75, and of the products, 72 Rockwell B. The crystalline chromium obtained was somewhat ductile but did not remain so after being melted into buttons tor hardness testing. Easiest to leach were the thin leaf-like crystals obtained at around 1 v. The thick heavy crystals produced at low voltage and current contained voids which made them difficult to leach free of chlorides. These changes did bring about large differences in the physical forms of the crystals obtained. Changes in bath analysis from 3 to 11 pct. had little or no effect upon the analysis of the metal produced, except for iron content. cell, variations in applied voltage from 0.05 to 1.5, in current from less than 10 to over 100 a., and in initial cathode current densities from less than 100 to over 2,000 a./sq.ft. In all cases the anode feed lay in the bottom of the container, which itself was used as the anode connection. A few runs in an iron cell with a nickel liner yielded chromium containing one half as much iron as the feed, but up to 1.5 pct. Since iron was entering the bath from the iron pot and the graphite liner at a nearly constant rate, contamination of the chromium deposits by it was more serious at low currents and deposition rates. ![]() The product usually contained a little more iron than the feed. Oxygen and nitrogen contents were reduced by a factor of 10 to 40, but most other impurities were little changed. The Federal Bureau of Mines refined chromium from an aqueous electrolytic process in molten sodium chloride-chromium chloride electrolytes. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |