If you would have painted walls, you would tell that directly painting metal isn’t a good idea. 

It is simply because the painted coating does not last long before it peels off from the metal.  Even worse is probably the corrosion induced by the trapped moisture in the painted coating that is poorly adhered to the metal surface.  The poor adhesion is attributed to the nature of the materials –the organic paint material is mostly non-polar, while the inorganic metal surfaces are polar – they are not fit each other well.  The poor binding strength is physically a weak Van der Waals force that can be easily broken.

To improve the organic-inorganic binding, a silane coupling agent can be applied to a pre-treated metal surface.  The special molecular structure of silane coupling agents, one end is polar, and the other end is non-polar, enables metals to chemically bond to polymers.  The principles seem simple.  To apply the principles correctly is another story. 

Dr. Chen demonstrates a new organic-inorganic coating procedure that is tailored in NASA’s interest.  He explores the possibility of using low-pressure air plasma, which is a green technology with simply the ambient air, to graft the surface of the sample metal, aluminum alloy AA2024-T3, with silane molecules for coating with polystyrene.  AA2024-T3, the strongest alloy in the alloy series of aluminum, is widely used in aerospace.  Polystyrene (PS), with the plastic recycling code 6, is popularly used in food packaging.  The outcomes of this project would serve as an alternative to the retiring chromate conversion coating which, albeit its cheap costs and wide applications contain soluble chromate ions that have an inherent toxicity concern.

Dr. Chen and his team are refining the coating procedure with needed tests for characterizing the coating performance.  These tests span the disciplines in mechanics, corrosion, spectrometry, and involved programming for data analysis.

RAW EIS data is available upon request. Approval of the data access is at Dr. Chen's discretion in good faith for research and development purposes.  Email an inquiry and your name, title, company/institute, and contact information to Dr. Chen at cchen4@alaska.edu