WC + Cr2O3 coating
11-26-2018, 05:24 PM,
#1
WC + Cr2O3 coating
Hello folks,

I am new in forum and in surface engineering as well. So please forgive me if I cant explain my problem correctly.

I need to coat a surface that is use for textile industry and it has to be highly wear resistant. Sample product has been analyzed to an university and they found WC-Co Cr and significant amount of Oxygen. And they couldnt decide coating was WC-Co + Cr2O3 or WC-Co-Cr. By the time sample product was used one.

As far as i know WC-Co can be coated by Hvof and Cr2O3 by plasma spray. So is it possible to coat this mixture with Hvof or plasma spray? or friction couses this significant amount of Oxygen on surface?

For your kind comments

Aydin




Reply
11-26-2018, 08:04 PM,
#2
RE: WC + Cr2O3 coating
(11-26-2018, 05:24 PM)Aydin Wrote: Hello folks,

I am new in forum and in surface engineering as well. So please forgive me if I cant explain my problem correctly.

I need to coat a surface that is use for textile industry and it has to be highly wear resistant. Sample product has been analyzed to an university and they found WC-Co Cr and significant amount of Oxygen. And they couldnt decide coating was WC-Co + Cr2O3 or WC-Co-Cr. By the time sample product was used one.

As far as i know WC-Co can be coated by Hvof and Cr2O3 by plasma spray. So is it possible to coat this mixture with Hvof or plasma spray? or friction couses this significant amount of Oxygen on surface?

For your kind comments

Aydin

Both materials can be applied with HVOF and Plasma Spray. Each method have final coat properties changing a little bit.

So answering your question. Yes it can be done, specially with Plasma Spray.

With HVOF system it depends on which HVOF system you are using. Some are able and others not so much. Let us know the equipment so the answer can be more precise.

Best regards.
Reply
11-26-2018, 08:41 PM,
#3
RE: WC + Cr2O3 coating
(11-26-2018, 05:24 PM)Aydin Wrote: Hello folks,

I am new in forum and in surface engineering as well. So please forgive me if I cant explain my problem correctly.

I need to coat a surface that is use for textile industry and it has to be highly wear resistant. Sample product has been analyzed to an university and they found WC-Co Cr and significant amount of Oxygen. And they couldnt decide coating was WC-Co + Cr2O3 or WC-Co-Cr. By the time sample product was used one.

As far as i know WC-Co can be coated by Hvof and Cr2O3 by plasma spray. So is it possible to coat this mixture with Hvof or plasma spray? or friction couses this significant amount of Oxygen on surface?

For your kind comments

Aydin

What kind of analysis was performed at university ? Xrd, Eds ? Oxygen often shows up in these results as you do spray with flame and things tend to oxidize. I see no point in mixing those coatings. I would say its WC/Co/Cr as it is used in textiles to substitute hard chrome.
Reply
11-27-2018, 01:04 PM, (This post was last modified: 11-27-2018, 01:10 PM by Aydin.)
#4
RE: WC + Cr2O3 coating
Hello sprayloud

Both analysis was performed but i could not add here. Could you please inform me how i can send you the result of analysis?

Thanks.

(11-26-2018, 08:41 PM)sprayloud Wrote:
(11-26-2018, 05:24 PM)Aydin Wrote: Hello folks,

I am new in forum and in surface engineering as well. So please forgive me if I cant explain my problem correctly.

I need to coat a surface that is use for textile industry and it has to be highly wear resistant. Sample product has been analyzed to an university and they found WC-Co Cr and significant amount of Oxygen. And they couldnt decide coating was WC-Co + Cr2O3 or WC-Co-Cr. By the time sample product was used one.

As far as i know WC-Co can be coated by Hvof and Cr2O3 by plasma spray. So is it possible to coat this mixture with Hvof or plasma spray? or friction couses this significant amount of Oxygen on surface?

For your kind comments

Aydin

What kind of analysis was performed at university ? Xrd, Eds ? Oxygen often shows up in these results as you do spray with flame and things tend to oxidize. I see no point in mixing those coatings. I would say its WC/Co/Cr as it is used in textiles to substitute hard chrome.


Hello vcduramais,

In fact I dont have a machine and i think the best way is to find suitiable system after your advises. But first I need to find out which method is suitiable for mixture of these powders. And as sprayloud's reply , first we need to figure out powder by examining analysis result that i could not add here.

thanks

(11-26-2018, 08:04 PM)vcduramais Wrote:
(11-26-2018, 05:24 PM)Aydin Wrote: Hello folks,

I am new in forum and in surface engineering as well. So please forgive me if I cant explain my problem correctly.

I need to coat a surface that is use for textile industry and it has to be highly wear resistant. Sample product has been analyzed to an university and they found WC-Co Cr and significant amount of Oxygen. And they couldnt decide coating was WC-Co + Cr2O3 or WC-Co-Cr. By the time sample product was used one.

As far as i know WC-Co can be coated by Hvof and Cr2O3 by plasma spray. So is it possible to coat this mixture with Hvof or plasma spray? or friction couses this significant amount of Oxygen on surface?

For your kind comments

Aydin

Both materials can be applied with HVOF and Plasma Spray. Each method have final coat properties changing a little bit.

So answering your question. Yes it can be done, specially with Plasma Spray.

With HVOF system it depends on which HVOF system you are using. Some are able and others not so much. Let us know the equipment so the answer can be more precise.

Best regards.

Reply
11-27-2018, 05:02 PM,
#5
RE: WC + Cr2O3 coating
I really doubt they mixed WC-Co and Cr2O3 powders, it seems much more probable that they sprayed WC-CoCr with a combustion ratio that favored the oxidation of the particles in flight. Besides, the coating properties of a mix of ceramic and carbides would probably be worst than each coating of its own. It's also very unlikely that you could find spraying parameters that allow the deposition of both these particle types at the same time, because they have very different properties.

If you focus on spraying WC-CoCr, HVOF is your best bet. Coating properties will be much better than what you can obtain with plasma, and the process is more simple.
Reply
11-29-2018, 01:25 PM,
#6
RE: WC + Cr2O3 coating
Hi all,

Please kindly find EDS Analysis results below link:

http://i63.tinypic.com/2j666ja.jpg

For your kind comments
Reply
11-29-2018, 03:32 PM,
#7
RE: WC + Cr2O3 coating
(11-29-2018, 01:25 PM)Aydin Wrote: Hi all,

Please kindly find EDS Analysis results below link:

http://i63.tinypic.com/2j666ja.jpg

For your kind comments

This is quite unusual composition. It is by no means typical HVOF blend WC86C010Cr4. Tungsten carbide is nothing more than additives here, but the main part is actually Cr2O3. Very unusual is the extremely high carbon content. Normally EDS shows no carbon at all.
It would be helpful to make a SEM image of the layer cross section. With SEM images, it is quite easy to identify phases within the coating.
Reply
11-29-2018, 04:51 PM, (This post was last modified: 11-29-2018, 04:53 PM by Aydin.)
#8
RE: WC + Cr2O3 coating
Hi Vadim,

Thank you for your reply.
This pic. can help you? :

http://i65.tinypic.com/2vlw2n8.jpg

Any other termal spray suggestion for this?


(11-29-2018, 03:32 PM)Vadim Verlotski Wrote:
(11-29-2018, 01:25 PM)Aydin Wrote: Hi all,

Please kindly find EDS Analysis results below link:

http://i63.tinypic.com/2j666ja.jpg

For your kind comments

This is quite unusual composition. It is by no means typical HVOF blend WC86C010Cr4. Tungsten carbide is nothing more than additives here, but the main part is actually Cr2O3. Very unusual is the extremely high carbon content. Normally EDS shows no carbon at all.
It would be helpful to make a SEM image of the layer cross section. With SEM images, it is quite easy to identify phases within the coating.

Reply
11-29-2018, 06:01 PM, (This post was last modified: 11-29-2018, 06:02 PM by Vadim Verlotski.)
#9
RE: WC + Cr2O3 coating
Hi Aydin,

Your picture is very bad, but I can see the following:

1. Your coating is actually the normally Cr2O3 plasma coating, but spray powder has impurities of WC-Co-powder (maybe some WC-Co-powder has remained in the powder feeder).
2. Coating quality of your Cr2O3 is very poor (many large pores, high stresses in the layer and thus wide cracks).
3. A high carbon content in EDS analysis is most likely caused by polymer enbedment in pores (specimen preparation).

To show what a proper Cr2O3 coating should look like, I will add the following image:


Attached Files Thumbnail(s)
   
Reply
11-29-2018, 10:03 PM,
#10
RE: WC + Cr2O3 coating
(11-29-2018, 06:01 PM)Vadim Verlotski Wrote: Hi Aydin,

Your picture is very bad, but I can see the following:

1. Your coating is actually the normally Cr2O3 plasma coating, but spray powder has impurities of WC-Co-powder (maybe some WC-Co-powder has remained in the powder feeder).
2. Coating quality of your Cr2O3 is very poor (many large pores, high stresses in the layer and thus wide cracks).
3. A high carbon content in EDS analysis is most likely caused by polymer enbedment in pores (specimen preparation).

To show what a proper Cr2O3 coating should look like, I will add the following image:

Carbon might be from sealer used to seal pores of ceramic coating.
Reply




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