Report describes a technique for reducing the corrosion rate of aluminum by adding colloidal substances in a closed-loop system. Experimental work shows that the addition of graphite and colloidal hydrated aluminum oxide significantly reduces the corrosion rate in flowing high-temperature water

Draley, J. E.

Ruther, W. E.

English

NASA Technical Reports Server

February 1969	 Bricl69-10029 
.	 AEC-NASA TECH BRIEF 
TES
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Corrosion Reduction of Aluminum Alloys in Flowing High-Temperature Water 
A report has been presented which describes a tech-
nique for reducing the corrosion rate of aluminum 
by the addition of colloidal substances in a closed-
loop system. Experimental work showed that the 
addition of graphite and colloidal hydrated aluminum 
oxide significantly reduces the corrosion rate in 260°C 
water flowing at 7 rn/sec. 
Aluminum alloys have been developed that show 
good resistance to corrosion by static high-
temperature (<360 0 C) water; but the corrosion rate 
of these alloys rises substantially when a rapid flow of 
water is maintained past the surface. 
Previous work had indicated that, under static con-
ditions, cracksor pores in the corrosion product were 
plugged by a rapidly coagulating and depositing col-
bid. The normal source of this colloid was postulated 
to be the precipitation of a soluble aluminum species 
emerging from the cracks in the oxide film. 
In this study it was assumed that the increased 
corrosion of aluminum alloys in rapidly flowing, high-
temperature water is related to the difficulty of pre-
cipitating the colloidal corrosion products within the 
cracks. Predictions based on this hypothesis were ex-
perimentally tested. 
A series of experiments on Type 8001 aluminum 
showed that colloidal graphite and colloidal hydrated 
aluminum oxide could significantly reduce the corro-
sion rate in 260°C water flowing at 7 rn/sec. Corro-
sion rates approximating those obtained in static tests 
were achieved in the hydrated aluminum oxide colloid 
solution. 
Complex ing the soluble form of the corrosion prod-
uct to prevent precipitation resulted in higher cor-
rosion rates in a dynamic system, but not in refreshed 
static systems. The complexing agents did modify ini-
tial corrosion behavior in static systems. 
The total corrosion for one week in flowing 260°C 
water varied with small applied currents, increasine
when the sample was made the cathode, and decreas-
ing when made the anode. 
Arsenic trioxide solution also gave promise of 
being an effective corrosion inhibitor for high-
temperature corrosion of aluminum in flowing water. 
The primary alloy chosen for this investigation was 
Type 8001 aluminum (0.89 w/o Ni, 0.48 w/o Fe, 0.13 
w/o Cu, 0.11 w/o Si). The metal loss was measured 
by an eddy-current gauge. The amount of unreacted 
metal remaining in corroded specimens was also de-
termined by a destructive technique. A corroded 
sample was weighed, and its remaining metal dissolved 
in a methanol iodine solution. Collecting and weigh-
ing the undissolved corrosion product made it pos-
sible to calculate the metal weight by difference. 
The test loops of stainless steel used canned-rotor 
centrifugal pumps to maintain the rapid flow of solu-
tion past the samples at 5.5 or 7 meters/second. 
Refreshing water or solution was pumped through the 
equipment at a rate 1.5 liters/hr. A 260°C temper-
ature was chosen. 
Notes: 
The report includes a complete discussion of the 
experimental procedure and the results. 
This information may be of interest to metallur-
gists. 
Additional information may be found in "Corro-
sion of Aluminum Alloys by Flowing High-
Temperature Water," ANL-7227, January 1967, 
by J. F. Draley and W. F. Ruther of the Metal-
lurgy Division, Argonne National Laboratory, 
Argonne, Illinois. The report is available from the 
Clearinghouse for Federal Scientific and Technical 
Information, Springfield, Va. 22151; price: $3.00 
(microfiche $0.65). 
This document was prepared under the sponsorship of the Atomic 
Energy Commission and/or the National Aeronautics and Space 
Administration. Neither the United States Government nor any per-
son acting on behalf of the United States Government assumes any
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.
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4. Inquiries concerning this report may be directed 
to:
Office of Industrial Cooperation 
Argonne National Laboratory 
9700 South Cass Avenue 
Argonne, Illinois 60439 
Reference: B69-10029 
Source: J. E. Draley and W. E. Ruther 
Metallurgy Division
Argonne National Laboratory
(ARG- 10244)
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
is 
S., 
Brief 69-10029	 Category 03


Corrosion reduction of aluminum alloys in flowing high-temperature water

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