Metal finishing Q&As since 1989

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Coating on copper to save from molten zinc

 

Dear Sirs,

My problem involves pouring of molten zinc between two copper vessels to remove heat from a system by conduction if the system temperature increases beyond a limit. But as we know molten zinc and copper form brittle intermetallic compound, I would be highly obliged if you could suggest a particular coating which if applied on copper shall protect it from molten zinc attack. Can we go for metallic coating of Mo-30W coating or some ceramic coating will do?

Thanks,

I.V. Dulera
- Mumbai, Maharashtra, India

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Nickel plating (about 0.0005") will keep the zinc away from the copper.

  
Tom Pullizzi
Falls Township, Pennsylvania
 

I agree with Tom Pulizzi regarding the metal of choice, not so in the thickness. Molten metals are aggressive and chemically active, thus they have a tendency to erode and corrode. Molds for the continuous casting of steel (melting point 1500 °C) are made of copper and protected by 1-2 mm of electroplated nickel. With zinc that melts at around 420 Cel, I would not hesitate to specify a minimum of 0.12mm (0.005").

Guillermo Marrufo
Monterrey, NL, Mexico
 

Dear Mr. Tom and Mr. Guillermo,

Thanks for your response but the website of a refractory metal site says that Ni dissolves in molten zinc and hence as such Hastelloy-X which is a nickel based superalloy cannot be used in molten zinc environment. I am bit apprehensive about using Ni coating. Any other suggestions? What about refractory metal coatings? whether they will help or anybody else has used them?

Thanks,

I.V. Dulera
- Mumbai, Maharashtra, India