Vapor Deposition of Tungsten by Hydrogen Reduction of Tungsten Hexafluoride

Abstract

An investigation of the variables involved in the deposition of tungsten from a mixture of tungsten hexafluoride and hydrogen has shown that the fastest rate of deposition (about 5 mils thickness in 2 min) was obtained at atmospheric pressure with a hydrogen/tungsten hexafluoride ratio of 1.5 (by volume) at a temperature of 800°–850°C. 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. The tensile strength of the deposits was about 30,000 lb/in.2. The internal stress within the deposits was also about 30,000 lb/in.2. Codeposition of carbon, from carbon monoxide, greatly increased the hardness of the deposits.