The lifetime assessment of low infrared emissivity composite coatings in chloride environments

The microstructural-electrochemical model is employed to predict the lifetime of low infrared emissivity composite coatings in chloride environments. Electrochemical data collected in 3.5 wt.% NaCl solution is presented for the low infrared emissivity coating, and these values are used as inputs for a mechanistic-based corrosion model which yields the salt spray life of the coating. To check the calculated results, the model predictions were compared with the results of salt spray tests. The current work showed that the model was able to predict lifetime of low infrared emissivity coating under salt spray, but tended to under-predict lifetime at short times and over-predict at long times. Under-prediction may be associated with corrosion protection of metallic pigment particles by polymer. Over-prediction by the model at longer exposure times may be associated with the fact that an influence of porosity is not included as a part of this simple model.