Dynamic Testing of Materials for Galvanising Pot Roll Bearings with Improved Performance

Area of Science:

• Materials Science
• Tribology
• Corrosion Engineering

Background:

• Galvanising pot roll bearings face severe degradation from corrosion in molten zinc (Zn).
• This corrosion leads to costly maintenance downtime, impacting industrial operations.
• Understanding material interactions in Zn-Al and Zn-Al-Mg alloys is crucial for improving bearing longevity.

Purpose of the Study:

• To evaluate the corrosion and wear resistance of different material pairs in molten Zn-Al and Zn-Al-Mg alloys.
• To identify material combinations that minimize degradation in galvanising pot environments.
• To assess the protective capabilities of WC-Co and Al2O3 coatings against molten metal attack.

Main Methods:

• Dynamic wear testing using a bespoke rig simulating galvanising pot conditions.
• Investigated material pairs: Wallex6™ with WC-Co, Stainless Steel 316L with Al2O3, and as-received Wallex6™ and Wallex4™ alloys.
• Analysis of corrosion products, intermetallic compound formation, and wear scars to determine wear coefficients.

Main Results:

• Al2O3 coatings exhibited excellent unreactivity in Zn alloy, while WC-Co materials corroded, forming Al-Co-Zn-Fe intermetallics.
• Wallex6™ and Wallex4™ alloys experienced Co dissolution and Zn/Al diffusion, though Zn diffusion reduced by ~60% in Zn-Al-Mg vs. Zn-Al.
• Minimal wear damage in both alloys was achieved only with Wallex6™ paired with Al2O3 coatings.

Conclusions:

• Al2O3 coatings provide superior corrosion and wear resistance for galvanising pot roll bearings in molten Zn alloys.
• Materials containing Cobalt (Co) are susceptible to corrosion and dissolution in these environments.
• Optimizing material selection, specifically using Al2O3-coated components, can significantly reduce maintenance downtime and costs.