low posoity with APS
05-28-2010, 08:30 AM,
#1
low posoity with APS
Hi everybody,

Long time ago I'm fighting with one of the NiCrAlY bond coat.

The requirement of the coating is stronger than normaly. I would try to rich very clean coating with very-very low porosity ( V1 ) with APS technology.

What I could rich until yet is V1-V2.

From the other side the unmelt content is also strong requirment.

Does anybody any idea how to rich that strict requirement?

Thank in andvance
Reply
05-28-2010, 09:01 AM,
#2
RE: low posoity with APS
I spent a lot of time setting parameters for NiCrAlY for aero industry applications, and the best result was obtained with 9MB APS torch, I TRIED WITH SG-100 APS Gun and F4 APS gun with not good result, so as well as it is a difficult material to set correctly parameters, in order to have the minor quantity of unmelted particles and low porosity if you have a 9MB gun, you can obtain the best result, I do not know why but it work.
Best regards
Luigi
Reply
05-28-2010, 10:55 AM,
#3
RE: low posoity with APS
Hi loriolo,


First I would say thanks for the replaying.

I've made also a couple of trial with F4 gun also with 6 mm nozzle and with 8mm nozzle also. Seems the 8 mm nozzle gives better result instead of 6 mm,but it is still not enough good.

After I made also trials with 3MB gun by argon, and seems this can gives the best result until jet but still not. In my opinion the 3MB gun is very similar to the 9 MB. Do you think am I right?

Anyway I heard also one possible solving methode. I made trial with lateraly positioned air flow ( let say air sweep ) to blow away all the dirty what is producing during the coating. Un-fortunatly this gives worst result from the unmelt point of view, because of the low temperature. That is why I'm thinking now to repeat the test under nitrogen with 3MB gun. In my opinion the nitrogen can gives higher melting beacuse of the inonisation energy is more ( let say ) aggressive. Could you tell me what kind of gas had been used? Argon or Nitrogen? Did you use any special technical things to rich the correct microstructure?

Thanks a lot

Sorry for my long answer
Reply
06-01-2010, 02:29 PM,
#4
RE: low posoity with APS
That’s Ok, if you use 8mm nozzle remember to use 2mm injector, because with the reduction of the gas speed, is necessary to reduce the powder speed, this if you use F4 gun, if you use 3MB gun, you could use N/H2 parameters, with feed rate 46gr/min instead of 60, the best result were obtained using nitrogen as primary gas, it is very important to check the perfect electrode alignment, and a perfect alignment of the powder stream in the flame, this is do with accuracy, in order to eliminate unmelted particles.
Regards
Best regards
Luigi
Reply
06-02-2010, 08:17 AM,
#5
RE: low posoity with APS
Thanks again for replying!

In case of the F4 gun ( 8 mm nozzle ) We've used 1.8 mm injector because we did not have 2 mm. To compensate it we've reduced the carrier gas flow.

What you wrote for me is a bit strange for me because I have totally opposite impression of the powder feed rate. I made couple of trial with 40 g/min and 60 g/min also. Seems the higher feed rate gave the better result for us. I'll try also exactly what you suggested the 46 g/min by Nitrogen.

If I have the result I'll let you know.

Thanks

Kopi
Reply
06-02-2010, 09:50 AM,
#6
RE: low posoity with APS
Hi Kopi

Sign0016 to the Surface Engineering Forum.

I won't interfere as loriolo seems to be advising well Smile
Reply
06-18-2010, 02:04 PM, (This post was last modified: 06-18-2010, 02:05 PM by Kopi.)
#7
RE: low posoity with APS
Hi Gordon,

Thanks


Hi Loriolo,

As I promised I made trial based on your suggestion.For me the N2 result is more dense. So probably to rich the correct porosity is easier with it.

Thanks a again


Seems N2 giving similar result as Ar. I feel , I very close to the end, just I have to
the rest of my commoent:

I have to make the fine tuning of the parameter
Reply




Users browsing this thread: 1 Guest(s)





Surface Engineering Forum Sponsor - Alphatek Hyperformance Coatings Ltd