roll in paper production

[Arturas]

Hello colleagues,
I have roll (length 5 meters) which work in quite aggresive atmosphere in paper production line . Temperature is about 70C , also there are water and water vapour. Roll material is St52-3N (C=0.25; Mn=1.6), hardness 220HB. At this moment surface is demaged mainly by corrosion but not by attrition. I want to restore surface and to increase resistant to corrosion with Ni/Cr (bond coat) and top layer stainless steel coating. But at the same time I am affraid that if corrosion will go down through the coating to the substrate the coating than peel off? What could be suggestions for this roll??
Best regards
Arturas

[Gordon]

Hi Arturas

A few questions:

Processes are you considering for coating application?
Coating thickness required for restoration?
Any other desired coating functions other than corrosion resistance?
How is coating to be finished? Can a relatively hard coating be used?

Potential coating formulations for this application could be quite large. Ask 20 knowledgeable people for their recommendation and you could get 20 different answers, possibly all fit for purpose Making coating totally impermeable to environment is a challenge, so application and choice of good sealer is important.

[Arturas]

Hello,
Process will be used for spraying is flame spray wire gun 11E
Coating thickness 1-1.5mm on side,
Coating functions are surface resistance to corrosion , and wear resistance but it is second not so important thing. I thing hardness about 40HRC should be enough
After spraying coating will be grinded
Yes hard coating also could be used here

What I am affraid is very high humidity , temperature about 90C and aggresive environment but what is ph here i don't know yet
So is it possible to use here stainless steel coating with post treated sealing . What are suggestions
Best regards
Arturas

(10-17-2009 03:40 PM)Gordon Wrote:  Hi Arturas

A few questions:

Processes are you considering for coating application?
Coating thickness required for restoration?
Any other desired coating functions other than corrosion resistance?
How is coating to be finished? Can a relatively hard coating be used?

Potential coating formulations for this application could be quite large. Ask 20 knowledgeable people for their recommendation and you could get 20 different answers, possibly all fit for purpose Making coating totally impermeable to environment is a challenge, so application and choice of good sealer is important.

[Gordon]

Hi Arturas

With Metco 11E you will need to convert to low speed gearing. With the readily available wires for this system, coating choice will be limited.

Ni/Al bond coat (Metco 405) + 13Cr steel (Metcoloy 2) - not sure whether this will have required corrosion resistance.

Somewhat softer coatings:

Ni/Al bond coat (Metco 405) + 13Cr steel (Metcoloy 2) + austenitic stainless steel (18/8 ss Metcoloy 1 or 316 Metcoloy 4). These austenitic steel coatings will require jacking up because of low thickness limitation.

Ni/Al bond coat (Metco 405) + high manganese austenitic stainless steel (Metcoloy 5) which should be good/better alternative to Metcoloys 1 and 4.

[Arturas]

Hello
Yes, the metcoloy 5 maybe is good solution but that material is very soft and what we also need is wear resistance so the hardness of top layer should be 30-35 HRC.
Why do you think that metcoloy 2 have not sufficient corrosion resistance. We also can use sealers? or it is not necessary ?

Arturas

(12-01-2009 05:57 PM)Gordon Wrote:  Hi Arturas

With Metco 11E you will need to convert to low speed gearing. With the readily available wires for this system, coating choice will be limited.

Ni/Al bond coat (Metco 405) + 13Cr steel (Metcoloy 2) - not sure whether this will have required corrosion resistance.

Somewhat softer coatings:

Ni/Al bond coat (Metco 405) + 13Cr steel (Metcoloy 2) + austenitic stainless steel (18/8 ss Metcoloy 1 or 316 Metcoloy 4). These austenitic steel coatings will require jacking up because of low thickness limitation.

Ni/Al bond coat (Metco 405) + high manganese austenitic stainless steel (Metcoloy 5) which should be good/better alternative to Metcoloys 1 and 4.

[Arturas]

Hello,
What about possibility to spray NiCrBSi using HVOF without fusing. The porosity lower will be than below mentioned coatings. Only not so good adhesion as after fusing. Maybe it could be solution? Or it would be enough 1-2% porosity that due to corosion coating pell off?

Arturas

(12-02-2009 07:32 AM)Arturas Wrote:  Hello
Yes, the metcoloy 5 maybe is good solution but that material is very soft and what we also need is wear resistance so the hardness of top layer should be 30-35 HRC.
Why do you think that metcoloy 2 have not sufficient corrosion resistance. We also can use sealers? or it is not necessary ?

Arturas

(12-01-2009 05:57 PM)Gordon Wrote:  Hi Arturas

With Metco 11E you will need to convert to low speed gearing. With the readily available wires for this system, coating choice will be limited.

Ni/Al bond coat (Metco 405) + 13Cr steel (Metcoloy 2) - not sure whether this will have required corrosion resistance.

Somewhat softer coatings:

Ni/Al bond coat (Metco 405) + 13Cr steel (Metcoloy 2) + austenitic stainless steel (18/8 ss Metcoloy 1 or 316 Metcoloy 4). These austenitic steel coatings will require jacking up because of low thickness limitation.

Ni/Al bond coat (Metco 405) + high manganese austenitic stainless steel (Metcoloy 5) which should be good/better alternative to Metcoloys 1 and 4.

[Gordon]

Hi Arturas

With any of the coatings, sealing will be important.

13 Cr steel (Metcoloy 2) will not be as corrosion resistant as the austenitic stainless steels. While being a lot better than plain steel coatings, it still has some potential to rust.

Arc or HVOF spray would be much more suited to this type of work. If you are going to be coating more of this type of work in future, sounds like a good time for investment in alternative processes.

[Stuart Milton]

Just to throw another option into the ring, arc sprayed Metallisation 103T (FeCrB) may be suitable. It's only suitable for arc spraying but produces a nice, hard coating (around 55Rc) with good corrosion resistance. This product and variants similar to it are widely used in the paper industry for rolls but not sure if it's in the exact roll application you are considering.

Contact us for more information if required or quite happy to continue the discussion on this forum.

[Gordon]

Hi Arturas

Missed your second post today as I was replying to first

Quote:What about possibility to spray NiCrBSi using HVOF without fusing. The porosity lower will be than below mentioned coatings. Only not so good adhesion as after fusing. Maybe it could be solution? Or it would be enough 1-2% porosity that due to corosion coating pell off?

Arturas

Yes, that could be a good option. I would seal coating for belt and brazes

If you have arc spray, Stuart's suggestion also sounds good.

[Arturas]

Hello Mr Stuart
Today I also discuss with your colleage Mr. Collin Arrow about this roll and we finally now consider NiCrBSI coating or 103T. But I do not have arc spraying system so the NiCrBSi/HVOF is maybe the only way in this case. Or there is any risk about peel off the coating due to corrosion.

Arturas

(12-02-2009 03:11 PM)Stuart Milton Wrote:  Just to throw another option into the ring, arc sprayed Metallisation 103T (FeCrB) may be suitable. It's only suitable for arc spraying but produces a nice, hard coating (around 55Rc) with good corrosion resistance. This product and variants similar to it are widely used in the paper industry for rolls but not sure if it's in the exact roll application you are considering.

Contact us for more information if required or quite happy to continue the discussion on this forum.

[Stuart Milton]

Hello Arturas,

I've spoken to Colin. As he mentioned, we need more information about the exact application and finishing requirements of the roll.

As has been mentioned above, there are many possible coating options and the more information available will guide you towards the most suitable coating for the application.

Without more information about the corrosion environment, I don't think anyone will guarantee that corrosion will not be an issue.

[k09]

Hi everyone!

I am taking this requirement of Mr.Arturas as a case study for myself

I had an option in mind and I wanted everyones suggestion if it is suitable for this particular application.

1. Ni-Al Bond Coat
2. SS-304 coat for restoring excess undersize
3. Ni-Al Bond Coat
4. Chrome Oxide ceramic top coat for corrosion resistance. ground and super-finished to required surface finish.

I am aware that they donot have an option for ceramic coatings but if they did, could this be a suitable and a technically feasible option. )

Regards

K09

[djewell]

(12-04-2009 04:55 PM)k09 Wrote:  Hi everyone!

I am taking this requirement of Mr.Arturas as a case study for myself

I had an option in mind and I wanted everyones suggestion if it is suitable for this particular application.

1. Ni-Al Bond Coat
2. SS-304 coat for restoring excess undersize
3. Ni-Al Bond Coat
4. Chrome Oxide ceramic top coat for corrosion resistance. ground and super-finished to required surface finish.

I am aware that they donot have an option for ceramic coatings but if they did, could this be a suitable and a technically feasible option. )

Regards

K09

That sounds like it would work, but it would be extremely expensive. The first two layers could be eliminated if the roll were not too far undersized.

[Arturas]

(12-15-2009 10:50 PM)djewell Wrote:  

(12-04-2009 04:55 PM)k09 Wrote:  Hi everyone!

I am taking this requirement of Mr.Arturas as a case study for myself

I had an option in mind and I wanted everyones suggestion if it is suitable for this particular application.

1. Ni-Al Bond Coat
2. SS-304 coat for restoring excess undersize
3. Ni-Al Bond Coat
4. Chrome Oxide ceramic top coat for corrosion resistance. ground and super-finished to required surface finish.

I am aware that they donot have an option for ceramic coatings but if they did, could this be a suitable and a technically feasible option. )

Regards

K09

That sounds like it would work, but it would be extremely expensive. The first two layers could be eliminated if the roll were not too far undersized.

Hello everyone ,
After all discussions I decided that first bond layer must be Ni80Cr20 -0.2mm(HVOF) and afterwards second layer Cr2O3 or Al2O3/TiO2 -0.6mm(flame spray). Plus sealer AP
What are opinions?
Arturas

[k09]

Hi Arturas,

If there is not much under-size than you could surely go for this option. But I would recommed Chrome Oxide in place of Alumina-Titania.

Everything else is fine but I have my concerns for 0.6mm thick Chrome Oxide coating. If you add 0.15 to 0.2 mm grinding allowance it would be 0.8mm!! I feel that is very close to the threshold limit for ceramic coatings.. I wud however like the experts to comment on this )).

Regards

K09

[Arturas]

(12-16-2009 10:57 AM)k09 Wrote:  Hi Arturas,

If there is not much under-size than you could surely go for this option. But I would recommed Chrome Oxide in place of Alumina-Titania.

Everything else is fine but I have my concerns for 0.6mm thick Chrome Oxide coating. If you add 0.15 to 0.2 mm grinding allowance it would be 0.8mm!! I feel that is very close to the threshold limit for ceramic coatings.. I wud however like the experts to comment on this )).

Regards

K09

Hi K09 ,
Why do you think that Cr2O3 is better than Al2O3/TiO2 in this case. And please comment about the thickness. Why it is to much, what can happen?

Regards
Arturas

[k09]

Hi,

I recommend chrome oxide you have mentioned in your first post that this roll is subjected to a very intense corrosive environment. Chrome Oxide has better corrosion resistance than alumina-titania.

I am not sure if you are aware but Chrome Oxide has poor deposit efficiency. its a meagre 15-20% (from Metco spec sheet).. From my experience some times its even lesser!! but the good news is flame spray has slightly higher spray rates than plasma but comparatively more porosity and less bond strength.

You can imagine how tiring it is going to be when you spray 5mt long roll!! We had once sprayed a 3mt long roll and we only needed 0.4mm thickness....it took for EVER with Plasma spray!!

The reason I say 0.8mm is on the higher side is because it has very low thickness limitation and I say this not only because its written in the metco 106 specification sheet but I have some practical experience with this. Further, if your base material has higher thermal expansion co-efficient it will only add to your troubles. At higher coating thickness, the relative thermal expansion and contraction would cause the coating to peel off.

For the reasons mentioned above, I would suggest to either restore the dimensions with SS 304 or SS 410 and then go for Chrome Oxide OR if you feel this is a longer procedure then apply slightly higher Bond coat and reduce the Chrome Oxide thickness to 0.3 to 0.4mm.

Regards

K09

[Stephen Booth]

Aturas, in my experience, the paper industry is reasonably well developed, and most of the key applications are "mature" with regards to thermal spray and Surface Engineering in General.

What is the name of the roll?
who is the manufacturer of the roll?
what are the operationing conditions besides water and vapour?
What are replacement rolls coated with, if anything?

However, just based on all this information, normally if only steam and limited abrasive wear, then if you have only wire flame, then consider the 13% Chrome Steel. It has been used on dryers and drying cylinders around the world for years, indeed it is only 35HRc, but it has pretty good wear resistance, it is proven, and cheap...

If you have HVOF CrC-NiCr or APS with Cr2O3, but make sure you can diamond grind, and achieve the surface Ra, Rz, TIR runouts for the 5 meters of hard coating.