Cold Spraying porosity
03-03-2010, 09:25 AM,
#1
Cold Spraying porosity
Hi all,

The part which it was cold-plated by NiCrBSi powder and has about % 30 porosity. We think that heating the cold-plated part in the furnace.
- What can we do decrease of porosity on the cold-plated part?
- What can we use furnace atmosphere for heating cold plated part?

Kind Regards
Reply
03-03-2010, 02:43 PM,
#2
RE: Cold Spraying porosity
Hi Attin

What is your aim/goal in this - a fused (hot) or cold processed NiCrBSi coating?

Quote:- What can we do decrease of porosity on the cold-plated part?
*Tailor powder to suit process better
* Increase velocity
* Increase gas/particle heating
* Post heat treatment fusing
* Change process to HVOF/HVAF or even flame spray or plasma.

Quote:- What can we use furnace atmosphere for heating cold plated part?
Vacuum furnace fusing would be best, but expect large volume change (shrink) in final coating.
Reply
03-04-2010, 08:38 AM,
#3
RE: Cold Spraying porosity
Thanks Mr. Gordon

"What is your aim/goal in this - a fused (hot) or cold processed NiCrBSi coating?"
The purpose of coating - to coat customer diamond abrasive saw (stones) with NiCrBSi powder (45 rockwell)

Can i heat the cold plated part in the hydrogen or nitrogen atmosphere furnace?

Kind Regards
Reply
03-05-2010, 04:09 PM,
#4
RE: Cold Spraying porosity
Hi Attin

Quote:Can i heat the cold plated part in the hydrogen or nitrogen atmosphere furnace?

Certainly, a lot better than air. Not sure on effect of coating and temperature on diamond. Think you will have to experiment. Getting a denser as-sprayed coating in the first place would beneficial though.
Reply
03-09-2010, 04:30 PM,
#5
RE: Cold Spraying porosity
As indicated by Gordon, you can't heat the diamond segmented saw in the fusion temperature range of NiCrBSi sprayed deposit.The temperature range of 950 - 1050*C would damage the silver brazing alloys used for joining the seagments to circular base, as well as diamond.you need to use
HVOF or Plasma spray to reduce porosity.
ram chattopadhyay
ram
Reply




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