08-25-2006, 12:52 PM,
(This post was last modified: 09-04-2006, 08:08 PM by Gordon.)
|
|
darende
Junior Member
|
Posts: 2
Threads: 1
Joined: Aug 2006
Reputation:
0
| |
TBC disbonding
Dear,
Aircraft engine combuster has been made from 5 panels and all of them has to be TBC coated. Recently just 1 panel's TBC ( 360 degrees ) has been disbonded completely after engine testing, while bond coat was in place and at good condition. We have already performed all quality tests requested by OEM manual.
Anybody can help me to understand the root cause
darende
|
|
08-25-2006, 02:06 PM,
|
|
Gordon
Administrator
|
Posts: 1,802
Threads: 70
Joined: Jun 2006
Reputation:
9
| |
RE: TBC disbonding
Hi darende
Welcome to the Surface Engineering Forum.
Is it possible to post more info on the coating system, equipment and spraying procedure? Also a good description of the failure or results from any failure investigation would be helpful. I appreciate that you may not be comfortable or allowed to post too much information on a public forum, but the quality of the information you provide may be reflected in response.
|
|
08-29-2006, 09:54 AM,
(This post was last modified: 10-05-2006, 11:36 AM by Gordon.)
|
|
darende
Junior Member
|
Posts: 2
Threads: 1
Joined: Aug 2006
Reputation:
0
| |
RE: TBC disbonding
|
|
08-29-2006, 04:27 PM,
|
|
Gordon
Administrator
|
Posts: 1,802
Threads: 70
Joined: Jun 2006
Reputation:
9
| |
RE: TBC disbonding
Hi darende
The only thing I can think of at the moment, is that something happened during the period from finishing the bond coat and starting the top coat. Contamination of the bond coat prior to top coating could well cause this type of problem.
|
|
10-15-2006, 02:11 PM,
|
|
Gordon
Administrator
|
Posts: 1,802
Threads: 70
Joined: Jun 2006
Reputation:
9
| |
RE: TBC disbonding
Quote:Hi Darende,
i suppose the debonding happen at the last panel or the first panel. What Gordon said is absolutely right!
It could due to contamination caused by handling or during in-process inspection. Bare hand touching could also be one of the problem. Make sure your guys use MEK or other cleaning solution to clean the part if it is touched or if they have concern about the part get contaminated during the spraying process.
Your yield is very good, this is a sporadic case anyway.
Regards,
Alex
I agree with Alex, but I think an awful lot of care and consideration needs to be made to cleaning grit blasted or bond coated surfaces. Cleaning with a cloth and solvent can in some cases just disperse the contaminants over a larger area and into the coating porosity and actually make matters worse. Best to ensure no contamination in the first place. Accidents will happen and it is at this stage that careful assessment is required, if in any doubt, remove coating and start again.
|
|
01-25-2007, 05:37 PM,
|
|
bhellman
Senior Member
|
Posts: 60
Threads: 9
Joined: Dec 2006
Reputation:
2
| |
RE: TBC disbonding
Gordon Wrote:Quote:Hi Darende,
i suppose the debonding happen at the last panel or the first panel. What Gordon said is absolutely right!
It could due to contamination caused by handling or during in-process inspection. Bare hand touching could also be one of the problem. Make sure your guys use MEK or other cleaning solution to clean the part if it is touched or if they have concern about the part get contaminated during the spraying process.
Your yield is very good, this is a sporadic case anyway.
Regards,
Alex
I agree with Alex, but I think an awful lot of care and consideration needs to be made to cleaning grit blasted or bond coated surfaces. Cleaning with a cloth and solvent can in some cases just disperse the contaminants over a larger area and into the coating porosity and actually make matters worse. Best to ensure no contamination in the first place. Accidents will happen and it is at this stage that careful assessment is required, if in any doubt, remove coating and start again.
Hi
Sometimes it is advisable to look for problems outside the actual spraying process. (remember human behavior and shut mouth).
bhe
|
|
01-27-2007, 08:09 PM,
|
|
volf
Member
|
Posts: 6
Threads: 3
Joined: Jan 2007
Reputation:
0
| |
RE: TBC disbonding
on your upper Fig. i see, that one side of the top coating extends over the base material,(coating over spray?), and that side passed separation. What is about top coating thickness? Is it in tolerance?
|
|
02-02-2007, 06:13 PM,
|
|
Gordon
Administrator
|
Posts: 1,802
Threads: 70
Joined: Jun 2006
Reputation:
9
| |
RE: TBC disbonding
Looking at the photo again, I think volf has made an important observation. Is this normal and are all the other panels/components the same?
|
|
|