Electrolytic Preparation of Zirconium and Hafnium Diborides Using a Molten Cryolite-base Electrolyte.
U S Pat 3 769 185 1973 Oct; :
Zirconium and hafnium diborides are synthesized in pure form from a molten cryolite bath under atmospheric conditions by electrolysis at 950 deg.-1050 Deg. C at a cathode current density of 10-225 a/dm2. The bath also contains small amounts of naoh or na2co3 and a sodium borate. Source compounds may be zr or hf oxides, the na salts of their oxyacids, or both with the atomic ratio of zr and hf to b of 1:4.5:2. Yields of zrb2 and hfb2 of 0.31 and 0.50 G/a-h, respectively, were obtained.
U.S. Pat. 3,769,185; Oct. 30, 1973; Chem. Abstr. 80:9,869Z