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Metal Coating
Evalution
We visualized one of the typical model corrosion
processes shown in one of the textbooks on corrosion as the second application.
A half portion of the nail was covered by copper and it was then placed on the
agar film formed on the sensor. pH values of a 5 mm by 15 mm region under the
pieces of rice were obtained at 100µm interval. The resulting pH values were depicted
so that the neutral pH region is yellow, the acidic region is red and basic region
is blue. The pH distribution was confirmed at those spots where the nail contacted
the agar film. Theoretically, the naked part works as anode and the copper coated
part as cathode, thus forming lower pH region around the point where naked part
contacted and higher pH region around the point where copper coated part contacted
, respectively. However, resulting pH image shows, for example, both anode and
cathode reaction occurred at the spot where the copper coated part contacted.
This can be explained by the incomplete coating of copper on the nail. Both the
coating copper and iron composing the nail under the coated copper contacted on
the agar and formed electrochemical cell thus generated both lower and higher
pH region. The incomplete copper coating was also confirmed by other microscopic
technique such as optical microscope and X-ray analytical microscope mentioned
at the beginning of my presentation.We visualized one of the typical model corrosion
processes shown in one of the textbooks on corrosion as the second application.
A half portion of the nail was covered by copper and it was then placed on the
agar film formed on the sensor. pH values of a 5 mm by 15 mm region under the
pieces of rice were obtained at 100µm interval. The resulting pH values were depicted
so that the neutral pH region is yellow, the acidic region is red and basic region
is blue. The pH distribution was confirmed at those spots where the nail contacted
the agar film. Theoretically, the naked part works as anode and the copper coated
part as cathode, thus forming lower pH region around the point where naked part
contacted and higher pH region around the point where copper coated part contacted
, respectively. However, resulting pH image shows, for example, both anode and
cathode reaction occurred at the spot where the copper coated part contacted.
This can be explained by the incomplete coating of copper on the nail. Both the
coating copper and iron composing the nail under the coated copper contacted on
the agar and formed electrochemical cell thus generated both lower and higher
pH region. The incomplete copper coating was also confirmed by other microscopic
technique such as optical microscope and X-ray analytical microscope mentioned
at the beginning of my presentation.
This results shows that evaluation of coating can be evaluated using our microscope.
Besides the metal coating, which was shown here, organic coating, for example,
to prevent the corrosion of substrate metal could also be evaluated in the same
method. For example, we have evaluated the surface coating of the video tape.
When the coating on the tape was degraded due to humidity and so on, the video
sample generated pH distribution on the agar thus enabling us to detect the degraded
coating. This way of evaluation is another proposal of us regarding the application
of this microscope. |
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![[genre_e]](../image/t_title.jpg){kind=small}
