In a composite Ni-20%Cr/ZrO2, ZrO2 particles coated with Ni electroless. In this composite for corrosion resistance,what is expected? Do nickel coating of zirconia particles improve corrosion resistance?Why? Why no?
It should be noted ZrO2 particles are in grain boundaries.
Dear Ehsan,
What do you mean by corrosion resistance? Corrosion resistance of ZrO2 particles (ZrO2 ceramic) or the corrosion resistance of the metallic substrate under permeable ZrO2 coating (plasma sprayed YSZ thermal barrier coatings for turbine blade)?
If you think that nickel has a higher corrosion resistance than ZrO2, you are absolutely wrong. ZrO2 is one of the most corrosion resistant material from all existing ones. It does not react with acids and alkalis, is stable in air to the melting point, is stable in many molten salts and silicate melts and so on. So protecting ZrO2 from corrosion with nickel plating is absurd.
However, if you think about corrosion protection of the steel substrate, then you are partly right. ZrO2 (YSZ) layers have a network of cracks and are permeable to corrosive media. In contrast, the layer of galvanic nickel is dense and protects underlying steel from corrosion in water and some salt solutions. Unfortunately, a combined ZrO2-Ni layer also becomes permeable and, therefore, makes little sense.
If you coat anything (ZrO2) with some other thing (Ni), that means the new coated material (Ni) is now work as the active surface and the previous material (ZrO2) is now not in direct contact of atmosphere. This process changes the corrosion behaviour of your material, and now the coated particles behave like a coating material (as far as corrosion is concern).
Dear Ehsan,
What do you mean by corrosion resistance? Corrosion resistance of ZrO2 particles (ZrO2 ceramic) or the corrosion resistance of the metallic substrate under permeable ZrO2 coating (plasma sprayed YSZ thermal barrier coatings for turbine blade)?
If you think that nickel has a higher corrosion resistance than ZrO2, you are absolutely wrong. ZrO2 is one of the most corrosion resistant material from all existing ones. It does not react with acids and alkalis, is stable in air to the melting point, is stable in many molten salts and silicate melts and so on. So protecting ZrO2 from corrosion with nickel plating is absurd.
However, if you think about corrosion protection of the steel substrate, then you are partly right. ZrO2 (YSZ) layers have a network of cracks and are permeable to corrosive media. In contrast, the layer of galvanic nickel is dense and protects underlying steel from corrosion in water and some salt solutions. Unfortunately, a combined ZrO2-Ni layer also becomes permeable and, therefore, makes little sense.
Vadim Verlotski
Thank you very much!
I coated ZrO2 Particle, because of improvement of adhesion of ZrO2 in Matrix. I'm looking to study the corrosion behavior of the material. Corrosion resistance of the metallic substrate under permeable ZrO2 coating. My substrate is Ni-20%Cr
If your substrate is a nichrome, then nickel does not increase corrosion resistance because nickel corrodes faster than nichrome in virtually all media. One reason why nickel is alloyed with chromium is the substantial increase in corrosion resistance.
When you coat Zr with Ni you must be aware that the coating may peel off if it does there is no corrosion protection
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