Surface Engineering Forum

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

Current time: 12-12-2019, 01:39 AM Hello There, Guest! (Login — Register)


Surface Engineering Forum / Surface Engineering / Surface Engineering Threads v
« Previous 1 ... 13 14 15 16 17 ... 33 Next »
/ Metco 58NS unmelt particles




Post Reply 
Threaded Mode | Linear Mode
Metco 58NS unmelt particles
02-10-2012, 03:45 AM
Post: #1
thezombiesprayer Offline
Member
***
Posts: 9
Joined: Nov 2011
Reputation: 0
Metco 58NS unmelt particles
[attachment=263][attachment=263][attachment=264]
Hi

Recently for the past few months, I have noticed in the increasing number of globular or unmelt particles in our coupons sprayed for the Metco 58NS coatings. Pls refer to pictures attached. They are quite big in size and sometimes the number exceeds the stated limits.
I have checked the feedrate of the powder as well as the spray distance and etc. But even when we spray according to our established parameters, we still experience quite a number of these globular particles in our microstructural tests.
Gun nozzles and spares are changed quite regularly according to our schedules.

Can advise what are the possible root cause to the problem and what changes can we do to eliminate these unmelts in the Metco 58NS coatings?
We have some spraying restrictions regarding the spraying distance due to the part configuration though.

Thanks

thezombiesprayer


Attached File(s) Thumbnail(s)
       
Send this user an email Find all posts by this user
Quote this message in a reply
02-10-2012, 04:01 AM
Post: #2
Joris Kraak Offline
Active Member
****
Posts: 47
Joined: Aug 2011
Reputation: 3
RE: Metco 58NS unmelt particles
Hi Zombiesprayer,

What gun are you using?!
- is your grain size distribution of the powder the same ?
- check injection in the plasma, the powder port might be mis-aligned. (sometimes happens with 3MBT or 9MB)
Send this user an email Find all posts by this user
Quote this message in a reply
02-10-2012, 04:57 AM
Post: #3
thezombiesprayer Offline
Member
***
Posts: 9
Joined: Nov 2011
Reputation: 0
RE: Metco 58NS unmelt particles
(02-10-2012 04:01 AM)Joris Kraak Wrote:  Hi Zombiesprayer,

What gun are you using?!
- is your grain size distribution of the powder the same ?
- check injection in the plasma, the powder port might be mis-aligned. (sometimes happens with 3MBT or 9MB)

Hi there

I'm using the F4MB 90 degrees gun.
For the powder grain size distribution, do you mean that we need to sieve the powder?
We did try sieving in the past, but ever since we have some experiments before sieving and w/o sieving seemed to be of similar results and we stopped sieving.
I shall check out the alignment of the gun.

P.S. I have read in another post that Metco 58NS is common to have some unmelts but as long as it falls within the stated limits of size and amount, we will be safe in the range?

Thanks

thezombiesprayer
Send this user an email Find all posts by this user
Quote this message in a reply
10-17-2012, 10:40 AM
Post: #4
vivian Offline
Junior Member
**
Posts: 4
Joined: Oct 2012
Reputation: 0
RE: Metco 58NS unmelt particles
Hi thezombiesprayer,

I have similar issue. Can you advise have the the unmelt particles resolved? If so, can you shear with me what to look for?

Thanks.
Send this user an email Find all posts by this user
Quote this message in a reply
10-18-2012, 07:41 AM
Post: #5
Spraytube Offline
Active Member
****
Posts: 13
Joined: Oct 2012
Reputation: 0
RE: Metco 58NS unmelt particles
Hi,

on the first hand, generally speaking,, having unmelt particle in a coating could be a lack of power transmitted to the particle.

There could be several reasons for that :

Carrier gas is not correct and the powder don't get in the plasma, the first things to do is leak checking the complete powder line.

Viscosity of the plasma is not correct and the powder can't get in the plasma or pass through : check your plasma gas parameters and calibrate your system.

"Power" given to particle is not correct, even if the gun maintenance is correct, most of the time we forget to check electrical hoses: a simple Voltage recording with fixed test parameters after a gun maintenance will give you good overview of the situation of your system.

On the other end, water conductivity could be an issue in your case, the unmelt particle in your view could come from the nozzle of the 9MB gun.

If you have a high water conductivity on a 9MB gun, small round "bubbles" of copper will appear on the nozzle and you will found them in the coating.
It will be really hard to detect it on a micrograph view especially in Cu/Ni/In coating.

You can visually see those copper "bubbles" on 9MB nozzle but the easiest thing to do is to measure the water conductivity.

Regards
Send this user an email Find all posts by this user
Quote this message in a reply
10-18-2012, 11:24 AM
Post: #6
vivian Offline
Junior Member
**
Posts: 4
Joined: Oct 2012
Reputation: 0
Big Grin RE: Metco 58NS unmelt particles
Thanks for the reply. I will work on these areas.

The OEM recommedation for water conductivity is <10 uS. The reading i have now is 2 uS. Not sure whether to have tighter control or not?

I have the folowing observations:
When the powder port is placed at +45 deg, the coating having high porosity % and unmelt % . However, the powder port is placed at -45 deg, the coating quality much more better and accetable to the spec.

I should get similar result regardless + or - 45. I not really understand this.

To get acceptable result, powder port is always set at -45 deg, but just recently observe higher unmelt particles in coating.

Also I am facing coating with low Vickers hardness result generally below 150 to 160 Hv. So far, I am trying to find out what are the factors affect this.

Regards
[/quote]
Send this user an email Find all posts by this user
Quote this message in a reply
10-18-2012, 12:55 PM
Post: #7
Spraytube Offline
Active Member
****
Posts: 13
Joined: Oct 2012
Reputation: 0
RE: Metco 58NS unmelt particles
(10-18-2012 11:24 AM)vivian Wrote:  Thanks for the reply. I will work on these areas.

The OEM recommedation for water conductivity is <10 uS. The reading i have now is 2 uS. Not sure whether to have tighter control or not?

That sound good for me.

(10-18-2012 11:24 AM)vivian Wrote:  I have the folowing observations:
When the powder port is placed at +45 deg, the coating having high porosity % and unmelt % . However, the powder port is placed at -45 deg, the coating quality much more better and accetable to the spec.

I should get similar result regardless + or - 45. I not really understand this.

To get acceptable result, powder port is always set at -45 deg, but just recently observe higher unmelt particles in coating.

This might be related to the relative position of the gun regarding the part or to the exhaust system. Check for eventual turbulence source.

(10-18-2012 11:24 AM)vivian Wrote:  Also I am facing coating with low Vickers hardness result generally below 150 to 160 Hv. So far, I am trying to find out what are the factors affect this.

Hardness is normally between 140-200 HV 0.3, you should increase you surface/traverse speed.

What are your parameters/system/powder feeder?
Are you using airjet?

Regards
Send this user an email Find all posts by this user
Quote this message in a reply
10-20-2012, 08:28 AM
Post: #8
vivian Offline
Junior Member
**
Posts: 4
Joined: Oct 2012
Reputation: 0
RE: Metco 58NS unmelt particles
Thanks again for the advices.

Parameters as follow:
powder flow rate: 45 g/min
H2: 6.6 NLPM
Ar: 37 NLPM

Equipment: APS Multicoat 9MB gun, with powder feed unit 9MPE-CL
Send this user an email Find all posts by this user
Quote this message in a reply
10-20-2012, 09:37 AM
Post: #9
Spraytube Offline
Active Member
****
Posts: 13
Joined: Oct 2012
Reputation: 0
RE: Metco 58NS unmelt particles
Hi,

I give you mine :

Spray distance : 90mm
Surface speed : 50 m/mn step 5 mm

Powder rate : 45 g/mn at 6l/mn (you should adjust this value according of how you see the powder get into the plasma), injector #2

Airjets : 4.5 bar crossing at 118 mm

Plasma : 550-570 amps if you are using thyristor power source, else remove 40-50 amps.
Gaz : ar:37 nlpm H² 6.8 nlpm

Nozzle GH

anyway you should be around 64-67volts.

I got better porosity result with an F4 gun.

Regards
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
  Sulzer Metco 58NS Copper-Nickel-Indium alloy powder question RaymondF2 1 795 09-05-2018
04:35 PM
Last Post: ServiceTech
  Metco 58NS coating coming off Christian_B 3 1,719 11-30-2017
04:19 PM
Last Post: Christian_B
  Reduce unmelted particles in Combustion Wire Spray Alberto Villalobos 8 5,029 05-19-2014
07:21 PM
Last Post: KevinS
  Need advice on unmelt particles in Metco 58 coating vivian 2 3,431 01-09-2013
06:25 PM
Last Post: loriolo
  Oxide stringers in Metco 58NS coating thezombiesprayer 2 4,056 08-13-2012
09:56 AM
Last Post: thezombiesprayer
  Difference between Metco 450NS and Metco 8400? Laurent 5 15,306 05-14-2009
12:39 PM
Last Post: SimonH
Sad Dark grey particles in Ni-Al bond coat? fhyuan 9 8,821 01-18-2009
07:02 PM
Last Post: Gordon

  • 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