The determination of oxygen in vacuum-melted steels, molybdenum and single-crystal silicon by vacuum fusion

Abstract

The equipment and techniques used for determining oxygen in vacuummelted steels, mol$bdenum and single-crystal silicon by vacuum fusion, at levels down to less than 1 p.p.m., are described.The oxygen content of steels at levels of 115 p.p.m. and 6 p.p.m. has been determined with coefficients of variation of 2.3 and 5.2 per cent., respectively. Results on sintered and arc-cast molybdenum with oxygen levels of 42 p.p.m. and 2 p.p.m. showed coefficients of variation of 2 and 8 per cent., respectively.Experiments with zone-refined molybdenum indicated that the oxygen content consisted of a residual surface contamination of 0-8 pg per sq. cm with an internal oxygen content of less than 0.2 p.p.m. With vacuum grown single-crystal silicon a coefficient of variation of 10 per cent. at a level of 17 p.p.m. was obtained on a limited sample weight of 0.5 g.

Ferrous Metallurgy

“…Vacuum fusion methods continue to be the subject for study and modification. Most modifications have been in the methods for recovering and measuring the evolved gas (19,37,84,185,215). Direct current arc heating in an argon atmosphere was used to liberate oxygen from samples as carbon monoxide which was then measured by means of its ultraviolet absorption (84).…”