THE KINETICS OF THE CORROSION OF LOW-HAFNIUM ZIRCONIUM IN AQUEOUS SULFURIC ACID SOLUTIONS
The rates of corrosion of low-hafnium zirconium in aqueous sulfuric acid solutions over the concentration range 9 to 97% by weight, were studied. Corrosion was detected by measuring the concentration of zirconium in solution with a radioactive tracer, Zr/sup 95/. The samples first were etched in an aqueous hydrofluoric-nitric acid solution then placed directly into the sulfuric acid solution, The initial corrosion followed a parabolic rate law which was followed by a constant rate, Corrosion during the constant reaction rate period was faster, by an order of magnitude or more than rates previously reported for unetched samples under similar conditions. This is thought to be due to the removal of the protective oxide film on etching and the subsequent growth of some less protective film in the sulfuric acid solution. The corrosion rate was found to be first-order with respect to undissociated sulfuric acid over the concentration range 0.2 to 9M of "undissociated sulfuric acid," STA31.4 to 81,1% H/sub 2/SO/sub 4/ by weight!, An equation relating the corrosion rate and the concentration of undissociated sulfuric acid at 44 deg C and with pre-etching, is: R = 4.0 x 10/sup -5/ x (H/sub 2/SO/sub 4/) + 1.0 x 10/sub -5/ (g cm/sub -2/ hr/sup -1/), An approximate value for the activation energy determined over the temperature range 20 to 72 deg C, is 7 to 8 kcal mole-t, A discussion of possible mechanisms is given. (auth)
- Research Organization:
- Atomics International Div., North American Aviation, Inc., Canoga Park, Calif.
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-14-006646
- OSTI ID:
- 4192091
- Journal Information:
- Journal of the Electrochemical Society (U.S.) Absorbed Electrochem. Technol., Journal Name: Journal of the Electrochemical Society (U.S.) Absorbed Electrochem. Technol. Vol. Vol: 107; ISSN JESOA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
Similar Records
Process for etching zirconium metallic objects
AN EVALUATION OF THE SULFURIC ACID-SODIUM NITRITE ETCH FOR ZIRCALOY-2