WC Co coating on bonding layer
07-19-2010, 05:04 PM, (This post was last modified: 07-19-2010, 05:05 PM by vevecaz.)
#1
WC Co coating on bonding layer
Hi everybody,

One of my colleague is sure than a "bonding and anti-corrosion layer" will increase the behaviour of WC-Co coating....Rolleyes
He thinks a total thickness WC-Co +?? of 0,35 mm coating on steel.

This could be NiCr layer or something else.
Is it a interest to do that or is there an incompatibility ?
Is an thick layer of WC-Co will be better?
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07-19-2010, 11:00 PM,
#2
RE: WC Co coating on bonding layer
I think your colleague is asking for trouble with a 0.35 mm thick WC-Co coating. HVOF/HVAF applied WC-Co will have a bond strength of 10,000 psi+ without a bond layer, so it is not necessary for enhancing the bond. A densely applied WC-Co coating will not corrode very quickly, and a good sealer will prevent corrosion from getting under the coating to attack the steel.
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07-20-2010, 06:24 AM,
#3
RE: WC Co coating on bonding layer
I would like to consider for thickness effect for toughness versus corrosion resistance.
And matrix metal's properties, especially Ni-Cr alloy has high strength and low toughness.
However cobalt has good toughness and bonding strength.
If substrate's hardness is lower than HV600, WC+NiCr coating is weak than WC-Co coating for impact stress.
Thick layer is favorable for use to corrosion environment, but bonding strength is less than thin layer case.
The boundary is about 100 micron meter.
Therefore 60 micron layer has better than 200 micron thick layer.

Simon
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07-22-2010, 03:53 PM,
#4
RE: WC Co coating on bonding layer
What about WC-CoCr or Cr3C2-NiCr coatings? That cermets do have enhances corrosion properties in comparison with simple WC-Co.


"Progress of science requires opportunity for share with no restriction all results and all point of views: this freedom of communication is indispensable for the development and extension of scientific knowledge". [A. Einstein]
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07-26-2010, 07:31 AM,
#5
RE: WC Co coating on bonding layer
Do you think that CrC-NiCr could be a good solution for corrosion ?
Is it better than WC-CoCr ?
Can we make bigger thickness with CrC-NiCr (near 150 - 200 µm) without cracks ?
I think WC-CoCr is more sensitive to cracks with thickness...
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07-29-2010, 02:09 PM,
#6
RE: WC Co coating on bonding layer
Hi vevecaz,
I've done coatings of either WC-CoCr and CrC-NiCr up to 300 µm without cracks. For lower thickness, imho, you would have no problem.
CrC-NiCr is an hot corrosion resistant cermet. If you are talking about corrosion in marine environment or other environments at ambient temperature, I think you could try also with sealant on other cermets.


"Progress of science requires opportunity for share with no restriction all results and all point of views: this freedom of communication is indispensable for the development and extension of scientific knowledge". [A. Einstein]
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