The Na <sub> 2 </ Sub> Of Wo <sub> 4 </ Sub> - Zno-wo <sub> 3 </ Sub> System, Surface Tension And Molten Salt-plated Tungsten,

Because of its many excellent wear/corrosion/high temperature resistant properties along with its costliness and brittleness, tungsten has found varieties of application in surface technology. In the present work, the electroplating of tungsten, one of the most promising methods to produce tungsten coating on refractory steel, from Na2WO4-ZnO-WO3 molten salts and salts'surface tension have been studied in order to make the coatings applied in liquid zinc.The surface tensions of melts were measured as function of composition and temperature. It was found that the surface tensions decreases with the temperature rising at 800~900℃, the relationship of them flows beeline approximately. Ion structures of melts relate to their compositions, and ion structures complex gradually and the surface tension decrease with the addition of WO3 at the same temperature. The surface tensions of melts rise with the concentration of ZnO increasing. The proper concentration of ZnO can simplified ion structure of melts.Cyclic voltammetry and chronopotentiometry have been applied to investigate the electrochemical mechanism of tungsten deposition in NZW melts. It was found that the electrodeprocess is a 6-electron transferred qui-reversible process. The diffusion coefficient of tungsten ion in NZW was measured as 4.77×10-7 cm2/s (920℃).By means of metallography and SEM, the optimum temperature was determined as follows: the temperature is about 900~950℃. Direct current and pulsing current were applied. The coating gained at 40mA/cm2 has well heat-shakeproof capability and can stand heat-impact from 900℃to room temperature. The coating and substrate link well.