DEPOSITION OF TUNGSTEN BY REDUCTION OF THE HEXAFLUORIDE WITH HYDROGEN IN THE VAPOR PHASE: PROCESS VARIABLES AND PROPERTIES OF THE DEPOSIT

An investigation of the variables involved in the deposition of tungsten from a mixture of tungsten hexafluoride and hydrogen has shown that the temperature of the substrate and the concentration of tungsten hexafluoride are the most important variables. The presence of hydrogen fluoride or chloride in the reacting gases diminished the rate of deposition. The deposits had about the same hardness, electrical conductivity and density as commercial wrought tungsten but had a higher purity. The tensile strength of the deposits was about 30,000 lb/sq in. and the stress within the deposits was of about the same magnitude. Codeposition of carbon, from carbon monoxide, greatly increased the hardness of the deposits. (Author)