Zirconium -fluoride ZrF

Three binary zirconium fluorides Zrp2, ZrF, and ZrF, are known to exist. The most important compounds industrially are zirconium tetrafluoride, ZrF, and fluorozirconic acid [12021 -95-3], H2ZrF, and its salts (see Zirconiumand zirconium compounds). 

Attempts to prepare zirconium trifluoride, ZrF, by the zirconium reduction of zirconium tetrafluoride were unsuccesshil, but it has been made by heating zirconium hydride to 750°C in a stream of hydrogen and hydrogen fluoride (179). 

Zirconium Fluoride (Zirconium Tetrafluoride), ZrF j mw 167.22 wh crysts, sp gr 4.43 mp 600°(subl) si sol in cold w decompd by hot w sol in HF. Can be prepd by treating ZrCl with anhyd HF or by thermal decompn of (NH )gZrF, which can be obtd by reacting ZrOg with NH HFg (Refs 1 3). Used as a component of molten salts for nuclear reactors Refs 1) Gmelin-Kraut Syst Number 42(1958), 278 2) Lange(1961), 332 3) Kirk ... 

With fluorine zirconium forms ZrF, when the oxide is heated with ammonium fluoride or when the chloride is treated with hydrogen fluoride. At 60° its solution begins to suffer hydrolysis, but on evaporating a solution containing free HF. a deposit is obtained to which the formula ZrF4 - 3 E O was formerly applied. It has some properties of a salt of this composition, but its behavior seems to indicate a composition ZrOF2 2 HF 2 H20.2... 

Refractory metals, such as tantalum and zirconium, can be deposited from their fluorides in a molten salt bath. In the case of zirconium, for example, the bath consists of ZrF or ZrF in a KF/NaF/LiF mixture. The alkali fluorides are employed to increase conductivity and decrease the melting point. Even so, these baths are operated at about 800 C. Good deposits have been reported as long as the right valency was chosen for each metal (3 for Mo and V, 4 for Nb and Zr, 5 for Ta). The bath must be operated in a pure argon atmosphere, and impurities must be strictly excluded. It siiould be obvious that the operation of such baths is expensive and control is difficult. Thus their use is limited either for research purposes or for highly specialized applications, where cost is of secondary importance. 

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