Mechanistic Study of Fungi Degradation of Organic Coatings Used in Aircraft Finish Systems
Technical Report,01 Mar 2017,30 Sep 2018
Naval Air Warfare Center Aircraft Patuxent River United States
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Navy and Marine Corps aircraft operate around the world most frequently in hot, humid environments where fungi such as mold and mildew spores attach and proliferate in regions of the aircraft without sunlightultraviolet light exposure. Chemicals and materials such as hydraulic fluids, corrosion preventative compounds, atmospheric contaminants and organic coatings act as a feedstock for microbes which leave by- products of organic acids, esterases, and lipases which are destructive to some coatings, corrosive to aluminum alloys and can lead to human health concerns. We hypothesize that a greater understanding of coating properties including surface roughness and free energy, chemistry , anti-microbial additives and contaminant films play a role in attachment and propagation of fungi where a greater understanding could suggest alternative means of mitigation. This study investigated the role of the following factors a two common topcoats with differing characteristics, b the corrosion inhibitor and topography of chromated vs. non-chromated primers, c hydraulic fluid contamination and d applied corrosion preventative compounds formulated with and without a fungistat. Five known fungi species were cultured on test panel surfaces for three months with and without contaminant films. Multiple analytical techniques were used to characterize species proliferating for each test condition, the degree of attachment to coatings surfaces before and after cleaningsanitizing techniques and incipient coating degradation. Analyses included laseroptical scanning microscopy, environmental scanning electron microscopy, light phase contrast microscopy, scanning Kelvin probe microscopy, electrochemical impedance spectroscopy, gas chromatography-mass spectrometry, gel permeation chromatography, attenuated total reflectance Fourier transform infrared spectroscopy and atomic force microscopy.
- Coatings, Colorants and Finishes