Final Report - Strategic Environmental Research and Development ...

Potential (V vs. Ag/AgCl)
-0.020
-0.040
-0.060
-0.080
-0.100
-0.120
-0.140
-0.160
-0.180
-0.200
0 20 40 60 80 100 120 140
Time (days)
HFA6 HFA7 HFC5 HFC6
Figure 6-7 Corrosion Potential Data for ESD Alloy 400 Deposited Onto K500
Specimens
6.2.3. GM9540P Cyclic Corrosion Testing
ESD coated specimens were positioned on a non-metallic rack in the GM9540P
accelerated test cabinet and exposed for 80 cycles (80 days). This exposure consists of a
combination of cyclic conditions including salt mist, ambient exposure, high humidity
exposure, and elevated temperatures. Specifics of the test cycle and solution are
described in Table 6-2. During the exposure, specimens were visually inspected
periodically without removing them from the test cabinet. After testing, specimens were
removed from the cabinet, fresh water rinsed, air dried and photographed.
After 80 cycles in the GM9540P cabinet, four of the eight ESD Alloy 400 specimens
exhibited corrosion on their surfaces with the attack concentrated predominantly at the
edges of the specimens. The corrosion initiated within 30 cycles of exposure in the
GM9540P cabinet. Metallographic evaluation of the corroded specimens is required to
determine the cause and extent of the observed corrosion, although Alloys 400 and K500
have a known susceptibility to localized corrosion in marine conditions [12,13]. Figure
6-8 shows a representative specimen before and after testing, highlighting the typical
degree of corrosion present.
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