Investigators: Gery Stafford, Carlos Beauchamp, Ed Escalante

Technical Description:

Electrogalvanized steel utilizes a variety of coatings, ranging from simple elements to rather sophisticated alloys. Coating thickness and composition standards have failed to keep pace; consequently there is little accountability among most sheet manufacturers both in the U.S. and abroad. Our objective is to develop the electrochemical expertise that will enable us to produce coating thickness (certified as mass/area) and composition standards of electrogalvanized coatings, starting with Zn and Sn and eventually the zinc-based alloys. These will be used by the steel industry to calibrate on-line x-ray fluorescence instruments for process control of continuous strip plating.

Technical Objectives:

• Develop prototype large panel thickness standards of Zn and Sn on 1010 steel. Coatings should consist of randomly oriented grains which are 5 µm-10 µm in size. Deposit thickness should be on the order of 1 µm to 10 µm.

• Identify the zinc alloys that are currently being used by the electrogalvanizing community. Determine composition, structure and level of uncertainty required by the industry.

Anticipated Outcome:

• Develop SRM prototypes for zinc and tin on steel. In addition, we expect to add to the science base for the electrodeposition of these metals.

Accomplishments for FY 1995:

• Demonstrated the electrodeposition of zinc on 1010 steel. Deposits of highest quality were obtained using a zinc sulfate electrolyte (pH=1.5) and a current density of 50 mA/cm².

• Succeeded in producing 10 cm x 15 cm coupons of zinc on 1010 steel. Target thicknesses of 3 µm to 8 µm were obtained with thickness variation within a coupon limited to 1.5%. Orientation was an acceptable 55% pyramidal.

• Identified two zinc alloys which will be the focus of future work. Zn-Fe (15-25 atomic % Fe) has good corrosion resistance and weldability. Zn-Ni (10-16 atomic % Ni) is by far the most popular, having exceptional hardness, good corrosion resistance and formability.

Impacts and Technical Highlights:

• We have demonstrated that zinc and tin can be electrodeposited on a 10 cm x 15 cm coupon of 1010 steel within the thickness and variability limits put forth by the continuous strip plating industry.

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Last modified: Mon Jan 06 09:46:15 1997 Metallurgy Webmeister