Method of making non-sag tungsten wire

摘要

It has been discovered that potassium retention in NS tungsten processing may be improved by double doping tungsten blue oxide (TBO) prior to reduction. The novel 'double-doping' process consists of dry doping standard singly doped K-Al-Si TBO with potassium nitrate, KNO3, followed by the standard reduction, acid washing, sintering, rolling and drawing steps. In another aspect, the novel method includes an aqueous extraction of heteropolytungstate anion [SiW11O39]8- from a sample of the singly doped tungsten blue oxide to predict potassium retention.