Hexafluorozirconic acid
Chemical compound
From Wikipedia, the free encyclopedia
Hexafluorozirconic acid is an inorganic compound with the idealized chemical formula H2ZrF6 that exists in solution. Hydroxonium hexafluorozirconate ((H3O)2ZrF6) is a white solid forming monoclinic crystals.
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| ECHA InfoCard | 100.031.502 |
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| Properties | |
| F6H2Zr | |
| Molar mass | 207.230 g·mol−1 |
| Appearance | white solid[1] |
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| H290, H301, H311, H314, H331 | |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Structure
Hydroxonium hexafluorozirconate has been characterized by X-ray diffraction.[3] It forms monoclinic crystals (space group: A2/a, a = 6.715 Å, b = 7.187 Å, c = 12.626 Å, γ = 111.85°, Z = 4). It is composed of chains of (ZrF6)2-
n, located in parallel to each other along coordinate axis x, and H3O+ cations.
Preparation
Hexafluorozirconic acid can be prepared by treating zirconium(IV) oxide with hydrofluoric acid.[1] White crystals form upon evaporation of the solution.
Uses
Hexafluorozirconic acid can be used in sealing treatments for phosphated steel. A dilute solution of trimethoxymethylsilane, with enough H2ZrF6 to bring the pH down to about 4, is reported to perform better than a chromate rinse.[4] A nickel and chromium(VI) free treatment system for steel and galvanized steel is carried out by washing with an alkaline cleaner, rinsing, treating with hexafluorozirconic acid, rinsing, and then sealing with a solution of epoxy phosphate.[4]