Photo Standards for TBC
09-17-2006, 09:09 AM,
#1
Photo Standards for TBC
I am looking for photomicrographic standards for metallographic evaluation of TBC coatings, primarily for turbine components. Can anyone help me on this?

Regards,

Girish Shejale
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09-21-2006, 11:59 AM,
#2
RE: Photo Standards for TBC
gshejale

Welcome to the Surface Engineering Forum.

First, I would check to see if the company you are doing the work for or the company that provides the coating specification have this information. Most aerospace companies have internal documents on coating evaluation and interpretation specific to their needs.

Your thermal spray equipment or powder supplier should have photographic standards, but probably only for typically good coatings.

Probably, the only way to have really useful standards specific to your needs and equipment is to prepare them yourself.
Reply
09-21-2006, 12:54 PM,
#3
RE: Photo Standards for TBC
Gordon,

Thanks a lot for your reply. Well, I am working for a turbine repair company. We do plasma spray coatings on turbine components like nozzle segments, combustion liners, transition pieces etc. This includes TBC as well as hard facing.

We do have internal specification for comparing the photomicrographs, but I am looking for some better standards like the one followed in aerospace industries.

I have been asking many people, but till date I have not got any such standards. I do understand such standards may not be readily available. But, I am sure this forum may be of great help.

Hope, you will guide me on this.

Regards,

Girish Shejale




Gordon Wrote:gshejale

Welcome to the Surface Engineering Forum.

First, I would check to see if the company you are doing the work for or the company that provides the coating specification have this information. Most aerospace companies have internal documents on coating evaluation and interpretation specific to their needs.

Your thermal spray equipment or powder supplier should have photographic standards, but probably only for typically good coatings.

Probably, the only way to have really useful standards specific to your needs and equipment is to prepare them yourself.
[/quote]
Reply
09-21-2006, 06:33 PM,
#4
RE: Photo Standards for TBC
Problem:

Who sets the standards?
Which coatings, process equipment and parameters?
Which metallographic preparation procedure?
Which viewing, magnification, photographic parameters?
Etc.?

This has been a problem for longer than I can remember and I don't see it being resolved soon (as a unified standard anyway).

A few links that should be interesting:

Standardization in Quality Control of Thermal Spray Coatings (part 2)

(sorry link dead)

More comments and links on this topic please.
Reply
09-25-2006, 09:35 AM,
#5
RE: Photo Standards for TBC
Thanks a lot Gordon for the useful links. I do undesrtand that there is still a problem on the standards. I wonder, why there is no ASTM standards on such coating evaluation. Hope, we get some more useful links to this.

Regards,

Girish Shejale


Problem:

Who sets the standards?
Which coatings, process equipment and parameters?
Which metallographic preparation procedure?
Which viewing, magnification, photographic parameters?
Etc.?

This has been a problem for longer than I can remember and I don't see it being resolved soon (as a unified standard anyway).

A few links that should be interesting:

Standardization in Quality Control of Thermal Spray Coatings (part 2)

(sorry link dead)

More comments and links on this topic please.
[/quote]
Reply
04-20-2007, 10:53 AM, (This post was last modified: 04-20-2007, 12:58 PM by Gordon.)
#6
RE: Photo Standards for TBC
gshejale Wrote:Thanks a lot Gordon for the useful links. I do undesrtand that there is still a problem on the standards. I wonder, why there is no ASTM standards on such coating evaluation. Hope, we get some more useful links to this.

Regards,

Girish Shejale


Problem:

Who sets the standards?
Which coatings, process equipment and parameters?
Which metallographic preparation procedure?
Which viewing, magnification, photographic parameters?
Etc.?

This has been a problem for longer than I can remember and I don't see it being resolved soon (as a unified standard anyway).

A few links that should be interesting:

Standardization in Quality Control of Thermal Spray Coatings (part 2)

(sorry link now dead)

More comments and links on this topic please.
[/quote]

Hi, there:

ERA has been providing metallurgical and failure analysis and condition assessment of industrial turbine components for operators, repair companies, and OEMs. Regarding coating quality approval on behalf of some OEM, we have oninging experience of many components (mainly hot section blades and vanes, conbustion tiles, etc), and the coatings we look at (sumitted by repair company) are invariably TBCs, MCrAlY (APS, LPPS, or HVOF), and diffusional aluminides on the external and internal (cooling hole) surfaces.

We have experiences of raising coatings specs for OEM's behalf in which the "4W" questions above are addressed. For a given coating (say TBC), the quality requirement is different from one make of component to that of another (WH vs GE) becasue of the complexity of the component design from each OEM. From that point of view, it would be difficult to envisage a universal (coating) standard agreed by all OEM (not to mention their reluctant to share info to competitors)...

So, to be a qualified supplier, repair company may still have to go through the process on a component and its make basis (rahter on the coating type).

Hong Wei Wang, Senior Metallurgist
ERA Technology, UK


Admin Note: Post date actually yesterday 19 Apr 2007
Reply
04-20-2007, 01:10 PM,
#7
RE: Photo Standards for TBC
Hi Hong (hwang)

Sign0016 to the Surface Engineering Forum.

Actually, delayed posting this to make sure it did not appear to arrive before you postedHappy0193
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