Thesis Abstracts 2004
Archived Content
Information identified as archived on the Web is for reference, research or recordkeeping purposes. It has not been altered or updated after the date of archiving. Web pages that are archived on the Web are not subject to the Government of Canada Web Standards. As per the Communications Policy of the Government of Canada, you can request alternate formats on the "Contact Us" page.
A Thermodynamic Model For Zinc-lead-bismuth Hot Dip Galvanizing Alloys
By: 2Lt Kevin Charles David Judd (MASc. - Chemical and Materials Eng)
Supervisor: Dr. W.T. Thompson
Abstract
Hot dip galvanizing is a valuable corrosion protective process applied to innumerable steel components annually. The zinc alloy traditionally contains a low concentration of lead, which imparts a spangled surface finish. For environment reasons, industry has made efforts to replace the lead with an element that also confers the expected finish. These efforts have determined bismuth to be an effective replacement or co-additive. A thermodynamic model of the Zn-Pb-Bi ternary alloy system has been developed. Emphasis in this activity was placed on the known binary phase diagrams and, in particular, the invariant conditions. This makes possible the computation of the Zn-Pb-Bi ternary phase diagram of interest in new galvanizing alloys. The model is based on the computed binary systems of Zn-Pb, Zn-Bi, and Pb-Bi. The observed binary phase diagrams are well reproduced with self-consistent sets of thermodynamic data. Experimental work in the form of zinc solubility measurements in the molten Pb-Bi rich alloy was performed. The findings were incorporated into a ternary alloy model by using the asymmetric Toop interpolation scheme. Computations of phase equilibrium can now be made in the Zn-Pb-Bi system for all compositions and temperatures of interest in hot dip galvanizing. This model has been developed in such a way that it can be modified, and expanded upon to eventually include additional components. This comprehensive model is expected to be of use to industry as a tool for the better understanding of the solidification of hot dip galvanizing coatings.
