| dc.description.abstract | The coating systems for military aircraft must protect the aluminum skin and
frame, and associated fastening and joining from corrosion in a variety of aggressive
environments. Excessive grinding is often needed to remove the corrosion products at the
cracks formed around the seams and fasteners on the aircraft resulting from poor system
flexibility of coatings, which causes high maintenance cost and damages the integrity of the
aircraft's body. Thus the U.S. Air Force wants to develop an advanced performance coating
system with a primer that can provide superior flexibility and good corrosion protection.
Currently commercialized magnesium-rich corrosion protection primers were initially
developed from some epoxy-amine coating systems, the most common polymer system for
aircraft primer use. But the primers were developed under the old specification, which
cannot meet the "ideal" goals of the Air Force. Thus, as a carefully selected alternate,
polysulfide modified polymers, which have lowest gas permeability, outstanding oil
resistance and UV resistance, and especially great flexibility, are being examined as
candidate materials.
In this research, a number of accelerated laboratory testing methods were applied
to measure the electrochemical and mechanical properties of the modified Mg-rich primers
which are based on polysulfide modified polymer as binder. Electrochemical measurement
results and visual inspections show that the Mg-rich flexible primer has better or equal corrosion protection performance versus a standard epoxy-based Mg-rich primer with the
same PVC. The flexibility of the newly formulated Mg-rich primer was also indicated by
the results of a variety of empirical testings and instrumental characterizations. Meanwhile,
the weathering impact introduced by the laboratory accelerated exposure cannot
compromise the superiority of the flexible Mg-rich primers. Based on the results found,
future work will be focused on creating a new formulate method or making some
modification of the sulfur-containing polymer's structure to achieve a really low VOC. | en_US |
