Hot-dip galvanizing is extensively used to enhance the mechanical, corrosive and aesthetic properties of steel. The basic component in the coating has been zinc. There has been a growing concern regarding the leaching of zinc into the environment and the industry has been searching for a better, lighter and stronger coating to further enhance the steel properties. This project is an attempt to address this issue.

A new alloy for batch galvanizing has been invented by Van Ooij which reduces the amount of zinc in the system. The alloy is the eutectoid composition of zinc and aluminum and this alloy was named Aleutec. My predecessor in this project Madhu Ranjan has narrowed the composition of Aleutec to zinc, 23 wt% aluminum and 0.35 wt% silicon. The steel has to be treated with the flux before it enters the bath and the conventional flux used in the industry was found to be ineffective with Aleutec. A novel flux was developed by Teck Cominco, Canada and Ferro Tech, Pittsburgh which gave very promising results with Aleutec. This zinc chloride and ammonium chloride based flux was named ‘G-Flux' and has a very low pH. Aleutec produced coatings which are thinner, stronger and offer better corrosive resistance than the conventional galvanized products. The coatings were characterized extensively studying the reaction mechanism and properties. A novel corrosion test which consists of alternate wetting and drying cycles was conducted to duplicate the environmental cycles. Aleutec showed great results in comparison with other alloys like the HDG and Zn 5 wt% Al.

Commercially available samples widely used in the galvanizing industry were coated with Aleutec. A variety of samples with complicated structures were also coated with Aleutec. Aleutec showed great results with the complicates shapes forming a uniform coating on all types of steels and also formed good coatings on welds, joints and corners. The alloy was tested for continuous galvanizing products like tubes and wires in a simulator called ‘RHESCA’ resulting is good uniform coatings..

The paint adhesion properties of Aleutec were also studied. Many surface treatments like zinc phosphating and silane coatings were tested to achieve good paint adhesion. The polarization resistance of the pretreated samples revealed that the silane treatment increased the polarization resistance of the coating. The zinc phosphating treatment improved the resistance further, but the resistance is still less than that of conventional HDG which displays good paint adhesion..

This thesis offers an outlook on the advantages and the shortcomings of this new alloy which will be useful for making the product commercially and economically acceptable.

Here's the link to the .pdf:

http://search.ohiolink.edu/etd/send-pdf.cgi/Narasimham%20Meghamsh%20Jayanthi.pdf?ucin1237741960

Enjoy the reading! ;)

Respectfully,
Henry