Coating delamination problem
05-21-2015, 02:09 PM,
#1
Coating delamination problem
Hi everyone,

what can be reason for delamination in my case?

1st layer Amdry 995c (0.1mm)
2nd layer Metco 204B-NS (0.25-0.3mm)

there is delamination between 1st and 2nd layer, time between operation is minimal 2-3min just for change powder from hooper.

Thank`s a lot, Sasa.


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06-14-2015, 11:09 PM,
#2
RE: Coating delamination problem
(05-21-2015, 02:09 PM)texnicar Wrote: Hi everyone,

what can be reason for delamination in my case?

1st layer Amdry 995c (0.1mm)
2nd layer Metco 204B-NS (0.25-0.3mm)

there is delamination between 1st and 2nd layer, time between operation is minimal 2-3min just for change powder from hooper.

Thank`s a lot, Sasa.


Hi Sasa,
What is the composition of your substrate?

What are your parameters for the 204B-NS?

Regards,
John.
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06-16-2015, 11:47 AM,
#3
RE: Coating delamination problem
Hi John,
Substrate is steel MSRR7036, i think that is not problem in substrate because connection between substrate and bond coat is good. I tried on other way with preheating substrate and i get good results into connection betwen bond coat and top coat but I have problem with delamination into layer of METCO 204B-NS (attached pic).


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06-16-2015, 11:08 PM, (This post was last modified: 06-17-2015, 12:04 AM by Johnny_Blaze.)
#4
RE: Coating delamination problem
(06-16-2015, 11:47 AM)texnicar Wrote: Hi John,
Substrate is steel MSRR7036, i think that is not problem in substrate because connection between substrate and bond coat is good. I tried on other way with preheating substrate and i get good results into connection betwen bond coat and top coat but I have problem with delamination into layer of METCO 204B-NS (attached pic).

Hi Sasa,
The image is kind of dark on my end but it does appear to be highly porous, it could be delaminating due to the cut-off wheel you are using to cross section the specimen. The thinner layer holds but as the thickness increases it loses its adherence ability.

High porosity and whether or not you are cutting into the surface of the top-coat inwards, or, from the substrate outwards when cross-sectioning can cause these issues as well.

The bond-coat may be adhering well but also shows large un-melted particles or partially melted particles and a lack of uniformity in your traverse rate.

The delamination is uniform in its length which would imply an equal pressure or load causing it to pull away.

Just a guess.

John
Reply
06-17-2015, 05:49 PM,
#5
RE: Coating delamination problem
Hi Sasa
I think that problem could be temperature during spray, or spray powder parameters do not well defined, you must preheat the piece at at least 50 °C, and you must be assured that substrate temperature remains constant during the coating process, the high Co content of the CONICRALY, could cause a surface oxidation if temperature raices to much, your are sure that there is not problem with metallographic test.
Best regards
Luigi
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06-19-2015, 11:29 PM,
#6
RE: Coating delamination problem
(06-16-2015, 11:47 AM)texnicar Wrote: Hi John,
Substrate is steel MSRR7036, i think that is not problem in substrate because connection between substrate and bond coat is good. I tried on other way with preheating substrate and i get good results into connection betwen bond coat and top coat but I have problem with delamination into layer of METCO 204B-NS (attached pic).

Hi Sasa,
I adjusted some of the contrast in the image to get a better look at the 204B-NS. There is very little melting of the particles your parameters are not sufficient to get good particle cohesion.

It would be interesting to know what you are using for gas flows, spray distance, current and voltage.

Regards,
John


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06-22-2015, 07:03 AM, (This post was last modified: 06-22-2015, 07:12 AM by texnicar.)
#7
RE: Coating delamination problem
Hi John,

Gun type: Metco 7MB
Pressure: Primary 100PSI, Secundary 50PSI
Flow: Primary 80FMR, Secundary 50FMR
Current: 450-500A
Voltage: 60-70V
Spraying distance 90mm (I tried with 50mm the results are pretty similarQuestionQuestionQuestion)
Preheating: 100-120 degrees celsious

I was tried next steps to get good results, but results are pretty same like before:
-reduce powder feed
-reduce spraying distance
-no preheating
-diffetrent bond coat (Amdry995C and Metco461 much better result with Metco461)

Do you have any suggestions?

I will try with different spray nozzle.

Regards, Sasa. (sorry for bad English)


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06-24-2015, 12:31 AM, (This post was last modified: 06-24-2015, 02:02 AM by Johnny_Blaze.)
#8
RE: Coating delamination problem
(06-22-2015, 07:03 AM)texnicar Wrote: Hi John,

Gun type: Metco 7MB
Pressure: Primary 100PSI, Secundary 50PSI
Flow: Primary 80FMR, Secundary 50FMR
Current: 450-500A
Voltage: 60-70V
Spraying distance 90mm (I tried with 50mm the results are pretty similarQuestionQuestionQuestion)
Preheating: 100-120 degrees celsious

I was tried next steps to get good results, but results are pretty same like before:
-reduce powder feed
-reduce spraying distance
-no preheating
-diffetrent bond coat (Amdry995C and Metco461 much better result with Metco461)

Do you have any suggestions?

I will try with different spray nozzle.

Regards, Sasa. (sorry for bad English)

Hi Sasa,
90-100mm is ok for the spray distance...pre-heat is good...I personally don't like FMR values because you need to have a pressure gauge before and after the flow tubes to properly calculate NLPM or SCFH.

I would also need to know which nozzle and powder port you are using.

I would suggest an Argon Insulator, GH Nozzle, No. 2 powder port, 200sfpm/ ~1000mm/sec with a step size of 0.180"/4mm per second.

550A - Adjust H2 until power of 38-40kW.
Argon FMR: 80.0 @ 75psi.
H2 FMR:~10.0 @ 50 psi. (or the flow value that brings your voltage between 70-75v @ 550A).
Carrier: FMR: 8.0
Feedrate: 8-10lbs/hr or 60 - 75g/min.

If you are still having unmelted top-coat particles, try and decrease the powder feed rate only until you get the desired results.

Regards,
John
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06-25-2015, 02:23 PM,
#9
RE: Coating delamination problem
Thank you John, I will try with you suggestion and I will report results here.
Reply
06-26-2015, 12:52 AM, (This post was last modified: 06-26-2015, 12:54 AM by Johnny_Blaze.)
#10
RE: Coating delamination problem
(06-25-2015, 02:23 PM)texnicar Wrote: Thank you John, I will try with you suggestion and I will report results here.

Hi Sasa,
Just out of curiosity, what is the simulated diameter for your test samples?

Will the samples be rotating or are you using a ladder/step program?

Regards,
John
Reply
06-26-2015, 06:53 AM,
#11
RE: Coating delamination problem
It was operated by hand and test sample was plate 50x70x1.2mm dimesion.



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06-26-2015, 11:24 PM, (This post was last modified: 06-27-2015, 06:43 PM by Johnny_Blaze.)
#12
RE: Coating delamination problem
(06-26-2015, 06:53 AM)texnicar Wrote: It was operated by hand and test sample was plate 50x70x1.2mm dimesion.

Well it definitely shows signs of better melting but still highly porous....are you using air jets pointed directly into your spray pattern?

Hand spraying is very difficult to maintain a consistent spray distance and uniformity, you have no means to automate the gun traverse?

The linear speed and traverse rate are critical in allowing for a uniform distribution of porosity, there are far too many variations with turbulence when hand spraying to have a balanced or homogenous distribution, this is why plasma spray is automated, it produces more consistent results.

To compete in today's market you really need to invest in an automated indexer or robot, reproducibility and repeatability depend highly on your gun manipulation system.

Regards,
John
Reply
07-07-2015, 02:09 PM,
#13
RE: Coating delamination problem
Hi,
I this is the last few trys with:
Metco 461 + Metco 204B-NS

550A, 75V
distance 90mm
powder feed 90g/min



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07-07-2015, 10:37 PM, (This post was last modified: 07-07-2015, 11:14 PM by Johnny_Blaze.)
#14
RE: Coating delamination problem
(07-07-2015, 02:09 PM)texnicar Wrote: Hi,
I this is the last few trys with:
Metco 461 + Metco 204B-NS

550A, 75V
distance 90mm
powder feed 90g/min

Hi Sasa,
It still appears to have too much porosity, there are also signs of layering indicating that your traverse is too slow.

The bondcoat also has large unmelts as well which will affect your adhesion, there seems to be a consistency in the way the layers separate in the micro-structure which could also mean that your being too aggressive when cutting/sectioning the sample, try a gentler approach to sectioning your samples.

You can try cutting your feedrate in half to 45g/min, but I would also be interested in knowing the parameters for your bondcoat.

As I mentioned previously, hand spraying is very difficult to establish a consistent spray distance, linear speed and step-size, cutting your feedrate down may improve particle cohesion and density in the top coat but you also need to get a few less unmelts in the bondcoat.

Amdry 995C has a smaller size range distribution than Metco 461NS, if you have that available, you may want to give that a try as well, although it is gas atomized as opposed to mechanically clad, it is spheroid in its morphology and may require a little more power to get the desired melting.

Regards,
John
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