Determination of the integrity of thermally sprayed coatings with a new laterally resolving electrochemical technique

摘要

The characterization of thermally sprayed coatings with the new scanning electrochemical technique allows for the non-destructive characterization of the prepared layers within a few tens of minutes. The obtained current signals can be easily evaluated statistically and correlated with the corrosion behavior observed in the 700 hours salt spray test. Hence, the technique is suited for the characterization of the effect of different spraying systems and spraying parameters and in quality control during production. These preliminary results indicate a correlation between the coating defects and the current signals. Hence, it is expected that physical and geometrical properties of the coating, such as permeability, density and porosity are linked to the obtained current signal. It is subject of future work to obtain a correlation between the electrochemical signal and the structural properties of the coatings. This will allow for fast evaluation of coating properties even during industrial production. Moreover, the short data acquisition time makes the technique a possible instrument for routine checks of coatings during service. This results in the possibility to follow the development of the coating properties during standard inspection. Based on these data the estimation of the expected life time should be possible.