Spots in TBC

[JBross]

We are spraying 204B-NS and have seen a few parts show up with red/brown spots. We perform cut ups and they extend through the ceramic and to the bond coat with is Amdry 9951 (CoNiCrAlY). We had SEM/EDS check for any iron or any other element thinking it may be rust, but results came back same as unspotted area. We have run samples in different booths, with different guns, with different powder lots, with different operators. Some parts show these spots and some do not. No common link yet. Anyone seen this in YZS before?

Thanks,
Jeff

[LEN WOOD]

See you're other post "Oxide anomalies in bond coat"

[plasmajet1990]

We are spraying 204B-NS and have seen a few parts show up with red/brown spots. We perform cut ups and they extend through the ceramic and to the bond coat with is Amdry 9951 (CoNiCrAlY). We had SEM/EDS check for any iron or any other element thinking it may be rust, but results came back same as unspotted area. We have run samples in different booths, with different guns, with different powder lots, with different operators. Some parts show these spots and some do not. No common link yet. Anyone seen this in YZS before?

Thanks,
Jeff

Do you cooled the samples with air ?

[KevGarty]

I agree with PlasmaJet (Jeff), I have seen similar spots on coating due to crap/moisture in cooling jets ?

[derek]

I agree with Jeff, this happens when you use cooling jets. If you don't see it but after heat treat, you may see it. Does it will affect the function of TBC? Maybe or may not, haven’t see any data to approval it.

[JBross]

See you're other post "Oxide anomalies in bond coat"

I do not believe it to be copper as we didn't find any element evidence in the SEM/EDS analysis. We have had the problem of bad spitting before from the nozzle and electrode but that was resolved with proper gun maintenance. Those spits didn't look like these.

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We are spraying 204B-NS and have seen a few parts show up with red/brown spots. We perform cut ups and they extend through the ceramic and to the bond coat with is Amdry 9951 (CoNiCrAlY). We had SEM/EDS check for any iron or any other element thinking it may be rust, but results came back same as unspotted area. We have run samples in different booths, with different guns, with different powder lots, with different operators. Some parts show these spots and some do not. No common link yet. Anyone seen this in YZS before?

Thanks,
Jeff

Do you cooled the samples with air ?

Yes we cool with air jets. I will look into that possibility. Thanks.
-Jeff

[Gordon]

Hi Jeff

Have you resolved your problem?

This does look very much like water/oil contamination from air cooling jets. Surprised you can see what look like stains in cross-section though, other than perhaps defects like lamination faults.

[JBross]

Hi Jeff

Have you resolved your problem?

This does look very much like water/oil contamination from air cooling jets. Surprised you can see what look like stains in cross-section though, other than perhaps defects like lamination faults.

I have attached a photo of the cross section with the discoloration. Not sure how it will look but you should be able to see the color all the way down to the bond coat.

[Gordon]

Hi Jeff

Dark field illumination shows it well. I would say its almost certainly caused by a fluid soaking through coating and leaving a stain.

Hi Jeff

Have you resolved your problem?

This does look very much like water/oil contamination from air cooling jets. Surprised you can see what look like stains in cross-section though, other than perhaps defects like lamination faults.

I have attached a photo of the cross section with the discoloration. Not sure how it will look but you should be able to see the color all the way down to the bond coat.

[plasmajet1990]

Hi Jeff

Have you resolved your problem?

This does look very much like water/oil contamination from air cooling jets. Surprised you can see what look like stains in cross-section though, other than perhaps defects like lamination faults.

I have attached a photo of the cross section with the discoloration. Not sure how it will look but you should be able to see the color all the way down to the bond coat.

Hi,

It is possible that the cooling air could have oil.
Try to change the cooling system or stop it.

Ion