How is nanoscale chemical evolution in corrosion resistant coatings monitored in-situ?
Xiaoyang Liu, Yu-chen Karen Chen-Wiegart, and their colleagues at Stony Brook University, Henkel Corporation, Brookhaven National Laboratory and NIST published on their use of the Hummingbird Scientific Gen IV in-situ X-ray liquid flow sample holder to characterize chemical evolution in corrosion-resistant Zr-based conversion nanocoatings. Synchrotron X-ray fluorescence spectroscopy (XRF), X-ray photoelectron spectroscopy (XPS), and X-ray absorption near edge structure (XANES) were combined for a multi-modal in-situ analysis of the coating formation process.
a) SEM image of sample. Fe XRF mapping b) before and c) after the experiment. d) Zr XRF mapping after the experiment. e) Fluorescence intensity of different elements during treatment process. X-ray fluorescence spectra at f) t = 0 and g) t = 3997.9 s. h, i) X-ray fluorescence intensity change of Zr, Cu, Fe, and Zn with time. j-l) Depth profiling Cu LMM Auger XPS of the s-32-120 sample with different sputtering times. Copyright © 2019 American Chemical Society
XRF was used to observe the evolution of Zr, Cu, Fe, and Zn concentration during the coating formation, with intensity changes indicating that Zr and Cu gradually and uniformly coat the substrate, while Fe dissolved into the solution. Quantification of sputtered coating clusters as function of time and temperature indicated a reaction-controlled mechanism for coating formation. XPS and XANES indicated that Cu-rich clusters embedded in the coating were primarily Cu2O, Cu, and CuF2, with cluster composition varying from the surface to internal region. The in-situ X-ray liquid flow sample holder enabled investigation of the mechanisms governing conversion coating formation and demonstration of a new methodology using in-situ synchrotron XRF.
Reference: Xiaoyang Liu, Donald Vonk, Hua Jiang, Kim Kisslinger, Xiao Tong, Mingyuan Ge, Evgeny Nazaretski, Bruce Ravel, Kate Foster, Stanislas Petrash, and Yu-chen Karen Chen-Wiegart, ACS Applied Nano Materials 2 (4) (2010) DOI: 10.1021/acsanm.8b02309
Full paper Copyright © 2019 American Chemical Society
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