RATES OF DISSOLUTION AND PASSIVATION OF HAFNIUM-FREE ZIRCONIUM IN HYDROFLUORIC ACID
The dissolution reaction of Zr in HF is: Zr + 4H/sup +/ yields and under the conditions of the experiments is much faster than that of Tl, and is a linear friction of the HF concentration (up to N - 0.5): V - 2000 N mm/sub 3/cm/ sub -2/min/sup -1/. A black hydride film is formed on Zr during its dissolution. Fluoride additions (NH/sub 4/F, KF, NaF) to the acid initially increase the rate of dissolution. When added in greater amounts, passivation of Zr is caused which is quite complete for NaF additions. The order of increasing effectiveness is NH/ sub 4/F yields KF yields NaF, apparently caused by the decreasing solubility of fluozirconate salt film formed on the metal. Potential measurements of Zr in HF showed an approach to a steady potential of about --0.74 volt with increasing concentration of the acid. The potential time curves had in general a logarithemic shapes the potential becoming more positive with elapsing time. Fluoride additions caused a breakdown of the initial film, formed during dissolution in pure HF, and a sudden drop of potential down to -1.112 volt (in 6.5 M NH/sub 4/F). The potential gradually became more positive, because of the salt film formation on the surface of Zrs until a steady potential was reached. Of the three additions, NaF produced and the most positive potential (-0.528 volt) and a complete passivation of Zr. (auth)
- Research Organization:
- Univ. of Missouri, Rolla; Stanford Research Inst., Menlo Park, Calif.
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-13-015080
- OSTI ID:
- 4241479
- Journal Information:
- Corrosion, Journal Name: Corrosion Vol. Vol: 15
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
Similar Records
THE DIFFERENCE EFFECT AND ANODIC BEHAVIOR OF ZIRCONIUM DISSOLVING IN HYDROFLUORIC ACID
RATES OF DISSOLUTION OF HAFNIUM METAL IN HYDROFLUORIC ACID
THE SOLUBILITIES OF KF, NaF, AND NH$sub 4$F IN H$sub 2$O, THEIR RESPECTIVE HYDROXIDES-H$sub 2$O, AND HF-H$sub 2$O SYSTEMS. A COMPILATION OF DATA FROM THE LITERATURE
Journal Article
·
Wed Jun 01 00:00:00 EDT 1960
· Journal of the Electrochemical Society (U.S.) Absorbed Electrochem. Technol.
·
OSTI ID:4156035
RATES OF DISSOLUTION OF HAFNIUM METAL IN HYDROFLUORIC ACID
Technical Report
·
Thu Dec 31 23:00:00 EST 1959
·
OSTI ID:4062222
THE SOLUBILITIES OF KF, NaF, AND NH$sub 4$F IN H$sub 2$O, THEIR RESPECTIVE HYDROXIDES-H$sub 2$O, AND HF-H$sub 2$O SYSTEMS. A COMPILATION OF DATA FROM THE LITERATURE
Technical Report
·
Tue Mar 25 23:00:00 EST 1958
·
OSTI ID:4307314
Related Subjects
AMMONIUM COMPOUNDS
CHEMICAL REACTIONS
CHEMISTRY
COLOR
CORROSION
CORROSION PROTECTION
DIAGRAMS
ELECTRIC POTENTIAL
EQUATIONS
FILMS
FLUORIDES
HAFNIUM
HYDRIDES
HYDROFLUORIC ACID
IMPURITIES
MEASURED VALUES
MIXING
POTASSIUM FLUORIDES
QUANTITY RATIO
REACTION KINETICS
SODIUM FLUORIDES
SOLUTIONS
SURFACES
TABLES
TITANIUM
ZIRCONIUM
ZIRCONIUM FLUORIDES
CHEMICAL REACTIONS
CHEMISTRY
COLOR
CORROSION
CORROSION PROTECTION
DIAGRAMS
ELECTRIC POTENTIAL
EQUATIONS
FILMS
FLUORIDES
HAFNIUM
HYDRIDES
HYDROFLUORIC ACID
IMPURITIES
MEASURED VALUES
MIXING
POTASSIUM FLUORIDES
QUANTITY RATIO
REACTION KINETICS
SODIUM FLUORIDES
SOLUTIONS
SURFACES
TABLES
TITANIUM
ZIRCONIUM
ZIRCONIUM FLUORIDES