Surface Science Western would like to congratulate Marshall Yang, winner of this year’s N. Stewart McIntyre Award in Surface Science. Marshall is a member of Dr. Hui Zhang and Dr. Jesse Zhu’s (Western Engineering) research group who specialize in particle fluidization, powder coatings and pharmaceutical coatings. Marshall’s work, which utilized a wide range of SSW instruments, focuses on improving the anticorrosive performance of powder coatings for outdoor use, by means of incorporating various additives.
Powder coatings are known for their economical, ecological, environmental and energy-saving benefits (“4Es”). They form barriers to protect various substrates from corrosion. Three additives utilizing different mechanisms are added into commonly used powder coatings. Different dosages or additive concentrations are compared to optimize the formulae for industrial uses. Another aim of Marshall’s project is the mechanistic inquiry into the interactions between the additives and polymer matrices of powder coatings.
At Surface Science Western, the sample panels’ top-down surfaces of different powder coating formulae are first characterized by SEM (Scanning Electron Microscopy) and confocal laser scanning microscope. Then the specimens are cut, epoxy mounted and polished for observing the cross-sections. The additive dispersion and defects inside the coating film are investigated qualitatively by the SEM images. Micro-CT (Computerized Tomography) is used to get 3D images of the internal structure, and data processing are performed to conduct various calculations on the re-constructed images, e.g. the connectivity of additive particles inside the polymer matrix. XRD and Raman laser spectroscopy are used to characterize the corrosion products at the localized corrosion spots after prolonged immersion in NaCl solution. Electrochemical techniques such as EIS (Electrochemical Impedance Spectroscopy) are used to get detailed information on the coating evolution and failure in the electrolyte.
Coatings are complex mixture of polymer binder and solid particles as additives. The sophisticated characterizations give great insight into the coating structures and transitions in the corrosive environment.