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Corrosion Inhibiting Non-Toxic Calcium Silicate Based Pigments

Surendranath, Arun
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1321888891

Abstract Details

2011, MS, University of Cincinnati, Engineering and Applied Science: Materials Science.
Anodic-cathodic pigments are mixed inorganic compounds, which in dispersed form, strongly inhibit both anodic and cathodic reactions, providing effective corrosion protection for Fe and Al based substrates. Such mixed anodic-cathodic pigment systems chromate/polyphosphate/zinc, zinc chromate, and red lead systems are examples, but toxicity from their use remains a troubling, unresolved issue. An important need exists, therefore, for development of non-toxic, inhibitive pigments as substitutes for the chromate-based pigments, with at least comparable corrosion inhibitor characteristics. In this Phase I work, inexpensive anion species of silicates and phosphates were combined with Ca and Ce cations to produce an effective, broad-based, corrosion inhibitive pigment system. The unique feature of this development is the chemical preparation of the complex silicate (CexCa(1-x)SiO3) pigments, under conditions such that the Ce ions partially substitutes for Ca ions on the lattice sites, giving enhanced surface and transport activity and enhanced electrochemical activity. Combinations of (Ce3Ca2+) anodic species, and (SiO32-, PO43-) cathodic species, as nano-sized pigments, were further prepared by co-precipitation and solution blending synthesis techniques, with pH control and ball-milling to reduce and control particle size, as appropriate. The scientific principle underlying this synergy, is that corrosion can be substantially inhibited if the electrons produced by the anodic reactions at the substrate surface can be diverted to more benign use through competing, thermodynamically more favorable reactions, such as the formation of Ca(OH)2 rather than Fe(OH)3, or being trapped at the active cationic defect sites. The prepared pigments were subjected to electrochemical, ICP/MS chemical analysis, and immersion evaluations and testing, to study the effectiveness of the various inhibitor species. EDAX of the immersion samples showed evidence of a complex film formation on the metal surface. The prepared pigments, after powder characterization, were further dispersed in an epoxy-polyamide carrier and coated onto Fe- and Al-based substrates for rigorous corrosion testing (humidity, salt spray testing), in evaluation procedures and protocols developed in conjunction with ECOSIL LLC, Sun‘s commercial based procedures.
Relva Buchanan, ScD (Committee Chair)
Dale Schaefer, PhD (Committee Member)
Jainagesh Sekhar, PhD (Committee Member)
106 p.
Materials Science
Corrosion; Inhibitors; Ceramic processing; Electrochemistry; EDAX mapping; Calcium silicate

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Citations

  • Surendranath, A. (2011). Corrosion Inhibiting Non-Toxic Calcium Silicate Based Pigments [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1321888891

    APA Style (7th edition)

  • Surendranath, Arun. Corrosion Inhibiting Non-Toxic Calcium Silicate Based Pigments. 2011. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1321888891.

    MLA Style (8th edition)

  • Surendranath, Arun. "Corrosion Inhibiting Non-Toxic Calcium Silicate Based Pigments." Master's thesis, University of Cincinnati, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1321888891

    Chicago Manual of Style (17th edition)

ucin1321888891
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© 2011, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.