T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol.
998
THE ANALYSIS OF MOLYBDENUM, COBALT, AND CHROMIUM ALLOYS By J. R. Camp and J. W. Marden CHEMICAL LABORATORY, UNIVERSITY OF MISSOURI, COLUMBIA, MISSOURI Received April 29, 1920
I n recent years certain alloys of molybdenum, cobalt, and chromium have assumed commercial importance. Stellite, which makes remarkable cutting tools, has been found b y t h e French government1 t o have twice t h e cutting power of t h e hardest carbon steel. I n a study of this alloy no difficulty was found in preparing metal somewhat similar t o stellite, b u t trouble was experienced in making t h e analysis. According t o Peele,z stellite consists of I O t o 2 j per cent chromium, 7 5 t o 9 0 per cent cobalt, with traces of molybdenum and tungsten. J ~ h n s o n however, ,~ gives its composition as: cobalt 6 0 . 8 0 per cent, molybdenum 2 4 . 1 0 per cent, chromium 13.20 per cent, with small amounts of iron, manganese, silicon, and phosphorus. Since t h e alloy is said t o be prepared in t h e carbon a r c furnace, a complete analysis should include a determination of carbon. T h e alloys t o be analyzed were prepared on a small scale b y t h e aluminothermic reduction of the oxides, using for preliminary trials 41.39 g. Coz04, 18.07 g. Mooz, and 9.7 g. Crz03, mixed with 22.6 g. aluminium, and about I O g. calcium fluoride t o slow up t h e reaction. I t was afterward shown t h a t these first samples were not very similar in composition t o stellite, as claimed b y either Peele or Johnson. Attempts were made t o analyze this alloy b y t h e method given b y Johnson. T h e following table shows t h a t incomplete separations were made on two different samples, some of t h e molybdenum separating with t h e cobalt and some of t h e cobalt with t h e molybdenum, making t h e total percentage considerably over 100. SAMPLEI ELEMENT Cobalt.,. . . . . . . . . . . . . . . . . . . 8 7 . 7 0 Molybdenum. . . . . . . . . . . . . 2 9 . 5 6 Chromium... . . . . . . . . . . . . . . 0.82
