The Longest Life Non-Stick Liquid Metal Corrosion-Resistant Coating for Sink Rolls (or Zinc Pot Rolls) – Boromet™ 144

Case Study
Hot-dip galvanizing (HDG) is the process of dipping fabricated steel into a kettle or vat containing molten zinc or zinc alloys. The hot dipping is carried out at temperature greater than 430˚C. In continuous galvanizing process, the steel strip is dipped in the molten bath through a series of sink rolls (or zinc pot rolls), which control the speed and tension of the strip and guide the steel strip through the molten metal bath. Since Zn at the elevated temperatures reacts with iron from the steel sheet as well as reacts with the surface of the rolls by causing dissolution, dross (alloy Zn-Fe or Zn-metal) is built up. This dross is attached to the rolls surface causing unacceptable defects in the steel sheet, since the dross particles are extremely hard (Zn hardness is 50 Vickers, steel hardness is 100 Vickers, and dross hardness is 700 Vickers). Additionally, this corrosive environment deteriorates the rolls functionality. When this happens, the line must be stopped and the rolls must be replaced.

Hybrid Materials LLC has completed extensive in-house lab testing and field-testing to prove the supremacy of the Boromet™ 144 coatings compared to the current state-of-art moly-boride thermal spray powders from Fujimi, Nippon, etc. and the conventional tungsten carbide thermal spray powders.