Aircraft-coating weathering studies by analytical methods

摘要

We predicted the life of an aircraft coating through the characterization of slightly weathered samples. To accomplish this, we completed accelerated weathering of a flat aircraft coating in a xenon-arc weather-o-meter for 0, 500, 1000, 1500, 2000, 2500, and 3000 h. Equatorial mount with mirrors for acceleration with aqua (EMMAQUA) exposures equivalent to 0, 6, 12, 18, 24, 30, 36, 42, and 48 months were also completed in this work. To determine coating-film degradation, we used electron spectroscopy for chemical analysis, also known as XPS, and L*a*b* color measurement. Nonlinear regression estimations were performed on selected measurements from the test data. Two models were used. The first was the Weibull-type model. The second was a Gauss-type model that had also been used in previous work on decay processes. The second model generally provided a better fit as determined by asymptotic R-2 statistics. Secondary-ion mass spectroscopy data did not produce data consistent with decay functions. The models better described the data from color change measurements and XPS. Fourier transform infrared data fit the models but not as well as XPS and color measurement. Furthermore, data from EMMAQUA exposures fit better than data from the xenon-arc weather-o-meter. In the model development work, we used single points for both measurement and exposure. The models can be refined with a high degree of predictive precision if replicates of 10 measurements and replicates of 5 exposures are performed; we plan to report these findings in the future. (C) 2002 Wiley Periodicals, Inc. [References: 31]