Accession Number : AD0003616
Title : THE ELECTROCHEMICAL POLARIZATION OF ZIRCONIUM IN NACL SOLUTIONS
Descriptive Note : Technical rept.
Corporate Author : TEXAS UNIV AT AUSTIN CORROSION RESEARCHLAB
Personal Author(s) : HACKERMAN, NORMAN ; CECIL, OLIN B
Report Date : 01 Dec 1952
Pagination or Media Count : 54
Abstract : Cathodic and anodic polarization curves of Zr in neutral NaCl solution were determined at constant current densities in the range of 3.5 x 10 to the power of -8 to 3.5 x 10 to the power of -3 amp/sq cm. All potentials were steady state. In aerated 0.5 M NaCl, the cathode reaction occurring below the O limiting diffusion current of 2 x 10 to the power of -4 amp/sq cm was the reduction of O to OH. At current densities above the diffusion wave, H was evolved. A change in salt concentration resulted in a slight shift of the diffusion current due to different O solubilities in the different salt concentrations. In deaerated 0.5 M chloride solution, the O diffusion current decreased with a decrease in O concentration. The value for the slope of the Tafel line was 0.12, and the H overvoltage was 0.83 v at 1 ma/sq cm. Another wave occurred at 2 x 10 to the power of -6 amp/sq cm and can best be explained as the reduction of a surface oxide layer on the metal. Anodically, Zr dissolved in 0.5 M NaCl. The dissolution potential, 0.15 v, was constant with a change in current density. Commerical Zr and pure Hf also dissolved under similar conditions. In neutral sulfate solutions, Zr was passive under anodic treatment. At the higher current densities, above 1 x 10 to the power of -3 amp/sq cm, the potential apparently reached a constant value in about 10 min, followed by a sudden increase in potential to 28.5 v. This high potential was a result of an IR drop across a surface of oxide present on the Zr coupon.
Descriptors : *ANODIC POLARIZATION , *ELECTRODEPOSITION , STEADY STATE , DENSITY , LAYERS , CURRENT DENSITY , SURFACES , CATHODES , OXIDES , LIMITATIONS , DIFFUSION , SALTS , SULFATES , CONCENTRATION(CHEMISTRY) , ANODIC COATINGS
Subject Categories : Inorganic Chemistry
Distribution Statement : APPROVED FOR PUBLIC RELEASE