Bonding coating for Cast steel subsrate

[plzc126330]

Dear Experts,

Hope everything goes well in your side!
I want to select a bonding coating for Cast steel substrate of piston ring parts, and top coating is CrCNiCr mix with Mo powder.

and bonding coating powder candidate are NiCrAlYs, CoNiCrAlY, NiCr, NiAl!
So any body could suggest which one is more better for this bonding coating and what are the reasons, any comments from your side will be great appreciates!

B.R

[Vadim Verlotski]

Dear Experts,

Hope everything goes well in your side!
I want to select a bonding coating for Cast steel substrate of piston ring parts, and top coating is CrCNiCr mix with Mo powder.

and bonding coating powder candidate are NiCrAlYs, CoNiCrAlY, NiCr, NiAl!
So any body could suggest which one is more better for this bonding coating and what are the reasons, any comments from your side will be great appreciates!

B.R

If you have a plasma spray system, would be a NiAl bond coat the best. Very good adhesion also provides the mixture of self-fluxing nickel-based alloy (NiCrBSi) with molybdenum powder (80% Mo + 20% NiCrBSi). When plasma spraying of this mixture you can even do without the top coat, because the layer Mo-NiCrBSi is hard and wear resistant.
If you have only a HVOF system, you can not really work with molybdenum. In this case, would be better Cr3C2-NiCr powder spraying directly on steel.

[plzc126330]

Dear Experts,

Hope everything goes well in your side!
I want to select a bonding coating for Cast steel substrate of piston ring parts, and top coating is CrCNiCr mix with Mo powder.

and bonding coating powder candidate are NiCrAlYs, CoNiCrAlY, NiCr, NiAl!
So any body could suggest which one is more better for this bonding coating and what are the reasons, any comments from your side will be great appreciates!

B.R

If you have a plasma spray system, would be a NiAl bond coat the best. Very good adhesion also provides the mixture of self-fluxing nickel-based alloy (NiCrBSi) with molybdenum powder (80% Mo + 20% NiCrBSi). When plasma spraying of this mixture you can even do without the top coat, because the layer Mo-NiCrBSi is hard and wear resistant.
If you have only a HVOF system, you can not really work with molybdenum. In this case, would be better Cr3C2-NiCr powder spraying directly on steel.

Dear Vadim,

Thanks a lot for your comments, yes, we only have plasma system so that why we try coat a bonding coating on cast steel base material, and top coating is CrCNiCr mix with Mo powder.
In the plan there has not bond coating, but after coating when did bond strength testing(OEMs requirement testing method apply on hardness testing device load to judge) with 5 Kg and 10 Kg load at interface, coating had cracks, we want to spray metal bonding coating to avoid crack when do bond strength testing. I am think which bonding coating powder after plasma spray could keep toughness which will not crack do strength testing.

B.R

[Vadim Verlotski]

Hi "plzc126330",

I fear that the simple mixture of a commercial sintered agglomerated Cr3C2-NiCr powder and a sprayable molybdenum powder is not the best solution for your application (coating for piston rings).
The Cr3C2-NiCr powder are, actually, optimized for HVOF spaying and not well suited for plasma spraying. In addition, the two powders (Cr3C2-NiCr and Mo) are quite poorly compatible with each other: it forms a very coarse distribution of the components, as both powders are grainy and have high melting temperatures.
In combination with molybdenum you need a low fusible metal component that can well envelope the molybdenum particles. That would be NiCrBSi alloy.

At the company Thermico GmbH we have applied such layers by A-60 plasma torch on valve stems:

[plzc126330]

Hi "plzc126330",

I fear that the simple mixture of a commercial sintered agglomerated Cr3C2-NiCr powder and a sprayable molybdenum powder is not the best solution for your application (coating for piston rings).
The Cr3C2-NiCr powder are, actually, optimized for HVOF spaying and not well suited for plasma spraying. In addition, the two powders (Cr3C2-NiCr and Mo) are quite poorly compatible with each other: it forms a very coarse distribution of the components, as both powders are grainy and have high melting temperatures.
In combination with molybdenum you need a low fusible metal component that can well envelope the molybdenum particles. That would be NiCrBSi alloy.

At the company Thermico GmbH we have applied such layers by A-60 plasma torch on valve stems:

Dear Vadim,

Thanks for your kindly explain, this powder recipe specified from OEMs, we can not change that, and we only have plasma system, so we have not choice try to achieve the coating performance target of the specification. then we want to spray a bond
coating try to avoid crack happen when 5 kg or 10 kg load testing.
And top coating powder is CrCNiCr(blend type) mixed with Mo.
We had failed experience many times without bond coating when load testing.
So I am considering keep bond coating toughness after plasma spray then could crack free when load testing, this is my idea and want to select bond coating powder for a trial.

B.R

[plzc126330]

Hi All,

Kindly view load test pictures, show interface crack happen when with 5, 10, 30kg load. So there will crack without bond coating.