oxide stringers in the bond coat
12-18-2007, 05:19 PM, (This post was last modified: 12-18-2007, 05:35 PM by fhyuan.)
#1
oxide stringers in the bond coat
Hi, everyone.

We sprayed Ni-graphite coating with Ni-Al bond coat. The puzzling problem is we have more oxide stringers (to a unacceptable level) in the bond coat when the Ni-graphite top coat is thinner.
Does anyone have the answer? Thanks.
Reply
12-18-2007, 05:50 PM,
#2
RE: oxide stringers in the bond coat
Hi fhyuan

Changes in top coat thickness should not have any significant effect on the microstructure of your bond coat (assuming nothing extreme is happening).
Reply
12-19-2007, 04:05 PM,
#3
RE: oxide stringers in the bond coat
The thickness of your top coat won't (or shouldn't, rather) have anything to do with stringers.. the amount of oxides/presences of clustering/stringers is directly related to air setup/flow and gun parameters.

You may need more air or to raise your parameters/spray to the max of each (ie high amps/volts, lower feed rate, etc).
Donald Richards
Product Engineering Technician
Cincinnati Thermal Spray, South
https://www.cts-inc.net
Reply
01-08-2008, 02:55 PM,
#4
RE: oxide stringers in the bond coat
If you are still having trouble with this could you please let me know what kind of spray system you are using. One of my operators was having this problem with a 9mb gun. It seems that the powder was not injecting into the flame properly, this created a "flame kick". Once we changed the carrier flow and changed the powder port so that the flame was no longer "kicked" the problems went away. I find that most problems are solved by getting in the booth and studying the flame.

Erick
Reply
01-08-2008, 03:55 PM,
#5
RE: oxide stringers in the bond coat
Hi Erick

Sign0016 to the Surface Engineering Forum.

Thanks for your input and I certainly agree with your statement:
Quote:I find that most problems are solved by getting in the booth and studying the flame.
Cheers
Reply
03-18-2008, 04:40 PM,
#6
RE: oxide stringers in the bond coat
I agree w/ others that the top coat thickness should not have an effect on oxide stringer.

Try sprying w/ a hydrogen rich parameter set (10-25% more than usual). I have always sprayed some of the dirty coating such as CrC-NiCr this way w/great results.

OK Ok, the nozzle will wear out faster but the result are worth it.
Reply




Possibly Related Threads…
Thread Author Replies Views Last Post
  Metallic HVOF bond coat to TBC APS top coat Gas turbines achmadarifudinh 0 737 07-08-2019, 08:34 AM
Last Post: achmadarifudinh
  Recomended bond coat for Metco 81 VFNS top coat achmadarifudinh 4 1,749 06-11-2018, 06:17 AM
Last Post: demionkrishan
  Bond coat for Metco 312NS Bharti Malvi 4 3,173 12-21-2016, 08:51 AM
Last Post: Bharti Malvi
  How do I do Bond Coat Selection? RV_DMG 2 3,174 03-13-2015, 11:44 PM
Last Post: loriolo
  Delamination in the bond coat sprayed on a Ti specimen Justin 9 7,774 01-06-2014, 10:00 PM
Last Post: KevinS
  Oxide stringers in Metco 58NS coating thezombiesprayer 2 4,669 08-13-2012, 09:56 AM
Last Post: thezombiesprayer
  I need advise on control of metco 405 bond coat Amoros 4 5,536 12-01-2011, 02:08 PM
Last Post: EmilyWatson
  Oxide anomalies in bond coat JBross 5 5,560 11-28-2011, 06:16 PM
Last Post: JBross
Shocked Cracks! in bond coat Christine 5 6,365 11-28-2011, 11:26 AM
Last Post: landemarre
  Possibility Study to use Stellite - 306 Bond Coat for 75Cr3C2 -25NiCr Top Coat -Reg sreenuvundela 2 4,639 09-14-2011, 05:36 AM
Last Post: sreenuvundela
  Aluminum oxide+titanium oxide schumi 11 11,566 04-19-2011, 11:15 PM
Last Post: loriolo
  oxide stringers and porosity In HVOF WC-CO wilfred1963 13 10,762 03-22-2011, 07:45 AM
Last Post: Khairul Anwar
  F50TF50 bond coat Harvey 6 7,932 07-10-2009, 07:01 PM
Last Post: derek
Sad Dark grey particles in Ni-Al bond coat? fhyuan 9 9,680 01-18-2009, 07:02 PM
Last Post: Gordon
  Bond coat raviswanadha 2 5,320 11-20-2007, 07:18 AM
Last Post: drramc



Users browsing this thread: 1 Guest(s)





Surface Engineering Forum Sponsor - Alphatek Hyperformance Coatings Ltd