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Prevention of Cathodic Delamination of Polyurethane from Titanium by Plasma Polymerized Silica/Aminosilane Primer Systems

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2017, PhD, University of Cincinnati, Engineering and Applied Science: Materials Science.
Thin silica-like films were deposited onto ferrotype plate, polycarbonate (PC), and Ti-6Al-4V alloy substrates with an atmospheric pressure plasma jet using hexamethyldisiloxane (HMDSO) as the precursor. It was found that the thickness, electrical, and mechanical properties of the film were sensitive to the flow rate of the precursor, the flow rate of ionization gas, the deposition distance, and the radio frequency power. Residual methyl groups were incorporated into the film when the distance between the nozzle of the plasma jet and the substrate was increased, or when the RF power used in deposition was decreased. This was confirmed by an increase in Si-CH3 peak intensity in the Fourier transform infrared spectroscopy spectra of the films. The atomic compositions of HMDSO-air plasma-polymerized SiOxCy films were analyzed by X-ray photoelectron spectroscopy. High RF power and low precursor flow rates produced films with carbon incorporation as low as SiO1.95C0.08. Low precursor flow rates produced smoother, more continuous, and more uniform films than high precursor flow rates. The hardness and scratch resistance of the films were measured by nano-indentation. As the film thickness increased, the hardness and modulus decreased. Scanning electron microscopy and atomic force microscopy were used to image the morphology of the substrates, deposited films, and scratch paths. Electrochemical impedance spectroscopy of the films were aquired in 3.5%wt NaCl solution. It was found the presence of silica-like films shifted the open circuit potential to a more positive value. The thickest film increased the impedance of bare titanium substrate by two orders of magnitude. Alkaline environment corrosion experiments were carried out in sodium hydroxide solution and the open circuit potential and corrosion current of the electrochemical cell were found to decrease with increasing silica-like film thickness deposited on the cathode. The rate of cathodic delamination of polyurethane adhesive from Ti-Al6-4V alloy was measured by double cantilever beam (DCB) testing of samples primed with silica-like films and ?-Aminopropyltrimethoxysilane (?-APS). The best performing silica-like primer film increased the initial fracture toughness of the DCB specimens by 50% and had a linear cathodic delamination rate of 0.106 mm/day under accelerated conditions. This was a at least a factor of five decrease in the rate of cathodic delamination compared to the primerless control.
F James Boerio, Ph.D. (Committee Chair)
Jude Iroh, Ph.D. (Committee Member)
Rodney Roseman, Ph.D. (Committee Member)
Vesselin Shanov, Ph.D. (Committee Member)
233 p.

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Citations

  • Han, B. (2017). Prevention of Cathodic Delamination of Polyurethane from Titanium by Plasma Polymerized Silica/Aminosilane Primer Systems [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491558395253426

    APA Style (7th edition)

  • Han, Bing. Prevention of Cathodic Delamination of Polyurethane from Titanium by Plasma Polymerized Silica/Aminosilane Primer Systems. 2017. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491558395253426.

    MLA Style (8th edition)

  • Han, Bing. "Prevention of Cathodic Delamination of Polyurethane from Titanium by Plasma Polymerized Silica/Aminosilane Primer Systems." Doctoral dissertation, University of Cincinnati, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491558395253426

    Chicago Manual of Style (17th edition)