The coulometric method may measure which coating- substrate combinations?
It measures electrically conducting metal coatings on metals or on plastics or on ceramics.
Which requirements must be fulfilled ahead of the coulometric measurement?
The following must apply: A clean coating surface, a good contact of the stand clamp to the specimen. Further one should choose a de-plating speed about as large as the relevant coating thickness. It is also important to pick the correct electrolyte.
Which factors determine the accuracy of the measurement for the coulometric method?
These factors are: coating thickness, surface composition, the applied measuring cell gasket, de-plating speed and the purity of the coating.
Does the factor 'density' play a role for the calibration?
Yes, this is the case.
Example:
At first the measurement instrument is calibrated with a sample and its coating's density has 2 g/cmยณ. Then a new sample shall be measured with a coating's density of 1 g/cmยณ. Without any new calibration a systematic measuring error will then occur. This means the measuring values would always be too small. This is the case, because the instrument rates the measuring signals of the new sample in such a manner, as if the coating's density also was 2 g/cmยณ.