Surface Engineering Forum

  • Alternative Forum Home PageSEF Portal
  • Old S E Message Board ArchivesOld Message Board Archives
  • Search
  • Member List
  • Calendar
  • Help

Current time: 12-14-2019, 09:30 PM Hello There, Guest! (Login — Register)


Surface Engineering Forum / Surface Engineering / Surface Engineering Threads v
« Previous 1 ... 3 4 5 6 7 ... 33 Next »
/ Porosity in D gun coating




Post Reply 
Threaded Mode | Linear Mode
Porosity in D gun coating
06-26-2017, 05:38 PM (This post was last modified: 08-16-2017 08:39 PM by DavidH.)
Post: #1
DavidH Offline
Junior Member
**
Posts: 3
Joined: Jun 2017
Reputation: 0
Porosity in D gun coating
We have been having trouble with high pressure(15,000 psi) seal integrity in a new valve which has an enhanced D gun coating of Carbide with a nickel and chrome binder on the shaft. We took some mold impressions of the sealing surface and inspected them under magnification and were surprised at the amount of what appears to be porosity. The coating is supposed to have around a .1% porosity level and there was a sealant applied prior to the grinding and honing process. Can anyone of the coating experts out there provide feedback on the amount of porosity present in the image and whether it is higher than normal for this type of coating and if there may be an issue with coating process, sealing process or materials involved.
Thanks,
David
[IMG]
https://imgur.com/IUfTqg1[/IMG]


Attached File(s) Thumbnail(s)
   
Find all posts by this user
Quote this message in a reply
06-26-2017, 08:48 PM
Post: #2
Vadim Verlotski Offline
SuperMember
******
Posts: 168
Joined: Sep 2014
Reputation: 9
RE: Porosity in D gun coating
(06-26-2017 05:38 PM)DavidH Wrote:  We have been having trouble with high pressure(15,000 psi) seal integrity in a new valve which has an enhanced D gun coating of Carbide with a nickel and chrome binder on the shaft. We took some mold impressions of the sealing surface and inspected them under magnification and were surprised at the amount of what appears to be porosity. The coating is supposed to have around a .1% porosity level and there was a sealant applied prior to the grinding and honing process. Can anyone of the coating experts out there provide feedback on the amount of porosity present in the image and whether it is higher than normal for this type of coating and if there may be an issue with coating process, sealing process or materials involved.
Thanks,
David

It doesn't look like porosity, but like outbursts. Such outbreaks can arise for several reasons:
1. Weak layer cohesion due to incorrect spray parameters
2. Too much content of oxides
3. Too hard grinding

If you are lucky and the cause lies with wrong grinding, the layer surface could become better by gentle grinding.
The problem with bad cohesion is more serious. In order to see if the layer is of sufficient quality, you have to make a microscopy of the cross section.
Send this user an email Find all posts by this user
Quote this message in a reply
« Next Oldest | Next Newest »
Post Reply 




Possibly Related Threads...
Thread: Author Replies: Views: Last Post
  8YSZ via F4-MBX porosity issue firegod 1 517 11-22-2019
09:03 PM
Last Post: Spraypowderengineer
  95 MXC Porosity vcduramais 8 678 09-09-2019
05:46 PM
Last Post: velocity
  Arc spray porosity problem velocity 6 788 06-01-2019
01:19 PM
Last Post: velocity
  Determination of Porosity demionkrishan 1 524 03-31-2019
02:37 PM
Last Post: Vadim Verlotski
  High porosity in WcCoCr demionkrishan 4 1,006 02-24-2019
06:16 PM
Last Post: loriolo
  Request for solution to reduce porosity in HVOF Tungsten Carbide Coatings sreenuvundela 6 7,378 05-23-2017
06:46 PM
Last Post: loriolo
  HVOF porosity sprayloud 4 3,160 11-28-2016
02:27 PM
Last Post: MVagusta
  How to determine the porosity level of Metco 320NS abradable coating? viewwer 6 4,585 11-23-2015
09:57 AM
Last Post: Joris Kraak
  Heat treatment after HVOF process to decrease porosity Giroud 3 3,588 07-13-2015
05:51 AM
Last Post: aerotherm
  yttria stabilized zirconia (TBC) Porosity issue cris1904 5 3,771 04-24-2015
12:56 PM
Last Post: Joris Kraak
  porosity in bronze wire spray KevGarty 1 2,286 07-22-2014
01:45 AM
Last Post: shantanu
  Porosity Problems Spraying Metco 72F-NS / Wc-114 J_rock 12 16,032 12-04-2013
05:18 PM
Last Post: JeffVigor
  porosity problem srihan_1 6 5,865 09-30-2013
08:12 PM
Last Post: KevinS
  Reduce Porosity in Ceramic Coatings rik 5 7,922 03-13-2012
10:05 AM
Last Post: loriolo
  oxide stringers and porosity In HVOF WC-CO wilfred1963 13 9,780 03-22-2011
07:45 AM
Last Post: Khairul Anwar

  • View a Printable Version
  • Send this Thread to a Friend
  • Subscribe to this thread


User(s) browsing this thread: 1 Guest(s)





Surface Engineering Forum Sponsor - Alphatek Hyperformance Coatings Ltd

    Subscribe in a reader

    Contact Us | Thermal Spray Coatings | Return to Top | Return to Content | Lite (Archive) Mode | RSS Syndication

Powered By MyBB, © 2002-2019 MyBB Group.


© Copyright Gordon England