Study provides insight into the oxidation mechanism of zirconium by combining electrical measurements with oxidation data. The measurement of electrical potential across growing scale on zirconium and the determination of conventional weight-change oxidation data were carried out at 550, 700, and 800 degrees C

Draley, J. E.

Drunen, C. J.

Levitan, J.

English

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'June 1968
	 Brief 68-10199 
• U,	
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Studies in Zirconium Oxidation 
This study was undertaken to provide insight into 
the oxidation mechanism of zirconium by combining 
electrical measurements with oxidation data. The 
measurement of electrical potential across growing 
scale on zirconium and the determination of conven-
tional weight-change oxidation data were carried out 
at 5500, 7000 , and 800°C. 
A report has been prepared which covers investiga-
tions of several independent topics. Oxidation rate 
is determined by standard methods to provide a base 
against which to compare the electrical measurements. 
The rate-limiting process and phase transformation 
are also studied, assessing the effect of volume change 
associated with tetragonal-monoclinic transforma-
tion as one of the causes for crack formation in the 
oxide. 
The potential-across the growing oxide is investi-
gated as a function of the influence of oxygen partial 
pressure at moderate-to-low pressures, and compared 
against weight-loss data under the same partial pres-
sure conditions. Measurements were also made under 
conditions involving zirconium reactions with nitro-
gen, carbon dioxide, and water vapor. 
The following is a brief summary of some of the 
results: Zirconium oxidation at 550 0 , 7000 , and 8001C 
follows rate lines that are between parabolic and cubic 
on a log-log plot, but not on a straight line. The 
oxidation kinetics are practically independent of the 
partial pressure of oxygen in pressures between I and 
400 mm. 
Resistance measurements of the oxide film at dif-
ferent stages of oxidation suggest predominantly
electronic control of oxidation, though control during 
the initial stages of oxidation was significantly ionic. 
This change is interpreted as being caused by the 
transformation of the initially formed tetragonal 
zirconia to the monoclinic modification. 
No measurable potential was produced in high-
temperature nitriding of zirconium, although even 
small amounts of oxygen added to a Zr+N2 system 
react to yield the oxide. 
Carbon dioxide oxidation of zirconium apparently 
involves a different mechanism and surface process. 
Resistance measurements and results of admission of a 
small amount of oxygen indicate that a different 
oxidation product probably is formed during CO2 
oxidation. 
Notes:	 - 
1. Additional information and data are contained in 
Studies in Zirconium Oxidation, by J. Levitan, 
J. Draley, and C. Van Drunen, ANL-7252, Decem-
ber 1966, Argonne National Laboratory, Argonne, 
Illinois. This report is available from the Clearing-
house foi Federal Scientific and Technical Infor-
mation, Springfield, Va. 22151; price: $3.00; micro-
fiche $0.65. Two other references to related work 
'are: (a) D. H. Bradhurst, J. E. Draley, and C. J. Van 
Drunen, "An Electrochemical Model for the 
Oxidation of Zirconium," Journal of the Electro-
chemical Society, 112, p. 1171-1177 (1965). (b) 
J. Levitan, J. E. Draley, and C. J. Van Drunen, 
"Low-Pressure Oxidation of Zirconium," Journal 
of the Electrochemical Society, 114, p. 1086-1089 
(1967).
(continued overleaf) 
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liability resulting from the use of the information contained in this 
document, or warrants that the use of any information, apparatus, 
method, or process disclosed in this document may not infringe pri-
vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19680000199 2020-03-12T05:37:07+00:00Z
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rected to:
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Argonne National Laboratory 
9700 South Cass Avenue 
Argonne, Illinois 60439 
Reference: B68-10199 
Source: J. Levitan, J. E. Draley, 
and C. J. Drunen
Metallurgy Division
(ARG- 10099)
Patent status: 
Inquiries about obtaining rights for commercial 
use of this innovation may be made to: 
Mr. George H. Lee, Chief 
Chicago Patent Group 
U.S. Atomic Energy Commission 
Chicago Operations Office 
9800 South Cass Avenue 
Argonne, Illinois 60439 
Brief 68-10199	 Category 03


Studies in zirconium oxidation

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