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PhD thesis _Xinyu Liu_ChemE.pdf (2.98 MB)

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Investigation of the Mechanism of Hydrogen Co-evolution during Electroless Deposition of Nickel and Cobalt Alloys

Liu, Xinyu
http://rave.ohiolink.edu/etdc/view?acc_num=case151992004637089

Abstract Details

2018, Doctor of Philosophy, Case Western Reserve University, Chemical Engineering.
Electroless deposition of nickel–phosphorus (Ni–P) alloy, facilitated by the use of sodium hypophosphite as reducing agent, is important to many industrial applications. During electroless Ni–P deposition, hydrogen gas evolves as a byproduct. In the present work, we first determine the source of hydrogen gas evolved by characterizing the deposition products and chemically analyzing the evolved gas. Specifically, we demonstrate that hydrogen gas evolves primarily due to chemical hydroxylation of hypophosphite anions catalyzed by the Ni surface and not due to electrochemical water splitting. Using volumetric measurements of the rate of hydrogen evolution on a rotating disk electrode, the effects of pH, hypophosphite concentration and hydrodynamics on the hypophosphite hydroxylation reaction are investigated. A mathematical rate expression is formulated, which incorporates the relevant kinetics and mass transport parameters affecting the hypophosphite hydroxylation reaction. Comparison of the model with experimentally measured hydrogen evolution rates allows precise determination of the rate constant and reaction orders. The transport-reaction approach developed for hydrogen generation in electroless Ni–P deposition was also applied to electroless deposition of Co–P where too hydrogen gas evolves via chemical hydroxylation of hypophosphite. The quantitative methods developed herein can be applied broadly to the study of gas evolution kinetics in chemical systems where access to the reaction rate is not available through amperommetry. Additionally, amorphous Ni–W–P films were fabricated using electroless deposition and characterized using microscopy and differential scanning calorimetry. Such characterization of the electroless Ni–W–P films indicated that addition of tungsten in the 1–3 at.% range improves the crystallization resistance of the as-deposited amorphous Ni–W–P films. The improved crystallization resistance may enable future applications of Ni–W–P alloys in Heat Assisted Magnetic Recording (HAMR) technology.
Rohan Akolkar (Committee Chair)
Chung-Chiun Liu (Committee Member)
Jesse Wainright (Committee Member)
Michael Hore (Committee Member)
112 p.
Chemical Engineering

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Citations

  • Liu, X. (2018). Investigation of the Mechanism of Hydrogen Co-evolution during Electroless Deposition of Nickel and Cobalt Alloys [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case151992004637089

    APA Style (7th edition)

  • Liu, Xinyu. Investigation of the Mechanism of Hydrogen Co-evolution during Electroless Deposition of Nickel and Cobalt Alloys. 2018. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case151992004637089.

    MLA Style (8th edition)

  • Liu, Xinyu. "Investigation of the Mechanism of Hydrogen Co-evolution during Electroless Deposition of Nickel and Cobalt Alloys." Doctoral dissertation, Case Western Reserve University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case151992004637089

    Chicago Manual of Style (17th edition)

case151992004637089
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© 2018, some rights reserved.Creative Commons License Investigation of the Mechanism of Hydrogen Co-evolution during Electroless Deposition of Nickel and Cobalt Alloys by Xinyu Liu is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.