Reduction of zirconium and hafnium oxides

Abstract

MANY attempts have been made to reduce zirconium dioxide with hydrogen. At temperatures up to 1,500°C. no positive results have been reported1-3. Newbury and Pring4 reported that at 2,500°C. and a hydrogen pressure of 150 atm. no reduction took place. Mott5 stated that in an electric arc at 6,000°C. and at a hydrogen pressure of 22 atm. reduction was difficult but that sometimes a small amount of "yellow Zr2O3" was produced. In the reduction of ZrO2 with lithium or calcium hydride it has been suggested that the active reducing agent is atomic hydrogen. Simonenko6, using a d.c. arc between tungsten electrodes, in a hydrogen atmosphere, claimed to have produced metallic zirconium from ZrO2 placed in the cathode cavity. He believed that the ions of molecular and atomic hydrogen were responsible for the reduction, their effectiveness being increased by the negative potential. © 1961 Nature Publishing Group.