DETERMINATION OF LESS THAN 10 PARTS PER MILLION CARBON IN TUNGSTEN

摘要

In the combustion-conductometric method the smallest detectible quantity of carbon is limited by errors introduced by a spurious carbon blank. Also, the accuracy of the method for refractory metals is unknown since quantitative calibration is based on recoveries of carbon from steel samples or on organic compounds. Studies of the control of these possible sources of error resulted in establishing conditions whereby carbon concentrations of 4 ppm may be determined with a precision of ±12 percent and an estimated accuracy of ±15 percent relative. These conditions appear to be directly applicable to other metals, including niobium, tantalum, titanium, zirconium, chromium, and copper.