HVOF 88 WC-12Co Cracking problem on wire drawing capstan
10-11-2016, 03:33 PM,
#1
HVOF 88 WC-12Co Cracking problem on wire drawing capstan
Good day partners

I have a craking problem in the 88-12 HVOF tungsten carbide coating on a wire drawing capstan, Actually we make the coatings with the HVOF thermal spray system using hidrogen- oxygen (gases).
We usually use TWAS 1/16 in carbon steel class ER70s-6 AWS 5.18 like a filling coating, this beacause the wire drawing capstans that we remanufacturing have several wear, approximately 0.090 in (0.180 in diameter) I think its a lot a probably this could be the reason that cause the cracking problem but Im not sure because this is not a problem often arising in the wire drawing, in addition we apply filling coating in the 90% of the capstans.

Do you have experience with this kind of problems??

Thank you for the support

I attach a photo of the problem.

Regards

Héctor Monjardin


Attached Files Thumbnail(s)
   
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10-12-2016, 05:31 AM,
#2
RE: HVOF 88 WC-12Co Cracking problem on wire drawing capstan
The bad performance of the HVOF O2/H2 sprayed 88/12 WcCo coatings is linked to directional an general micro-cracking, specially when applied at high thickness because the coating with HVOF O2/H2 has too much stresses, with HVOLiquid fuel the coating performance is better, I worked on this kind of applications for many years, every capstan coating depend of the type of wire they must work, in some cases is better to use Al/Ti oxides, sometime Ni13Cr or Cored Wc wire with HVOFWire
Best regards
Luigi
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10-12-2016, 01:18 PM,
#3
RE: HVOF 88 WC-12Co Cracking problem on wire drawing capstan
(10-12-2016, 05:31 AM)loriolo Wrote: The bad performance of the HVOF O2/H2 sprayed 88/12 WcCo coatings is linked to directional an general micro-cracking, specially when applied at high thickness because the coating with HVOF O2/H2 has too much stresses, with HVOLiquid fuel the coating performance is better, I worked on this kind of applications for many years, every capstan coating depend of the type of wire they must work, in some cases is better to use Al/Ti oxides, sometime Ni13Cr or Cored Wc wire with HVOFWire

Hi, good morning

Loriolo, actually we apply 0.008 in to 0.010 in of thickness, What do you think? For wire drawing process equipment we use 3 types of carbides using the HVOF system, 83 WC-17 Co, 88 WC-12Co, 87WC-10Co-4Cr, depending the type wire. In some cases we use Flame spray moly wire in capstans for application with corrugated wire.
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10-13-2016, 01:09 PM,
#4
RE: HVOF 88 WC-12Co Cracking problem on wire drawing capstan
Hector,

as far as I understood, you used duplex coating:
1. filling the worn part with TWAS
2. 200-250 microns WCCo

If it is the case, here could be a root of the problem:
TWAS coating is quite porous and does not provide enough base toughness for WCCo.

We have used two approaches successfully enough:
Spraying hard steel coating by flame spray Plackart FS15(less expensive, no WCCo at all)
spraying thick WCCo coating by Kermetico HVAF AK7 (better wear resistance)
BR
Vig
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10-15-2016, 10:28 PM, (This post was last modified: 10-15-2016, 10:29 PM by Met.Eng..)
#5
RE: HVOF 88 WC-12Co Cracking problem on wire drawing capstan
Hi Hector


Hi Hector


Hi Hector
try to mix some metco 15 F with your WC-Co powder, %20-25 as good results with WC-Co
And use bont coat under the top coat, my choice is ni5al arc spray under the top coat. What is your blasting mash number? May be try course blasting media for ex 16 grit Wink
Good luck
Reply
10-17-2016, 09:39 PM,
#6
RE: HVOF 88 WC-12Co Cracking problem on wire drawing capstan
(10-15-2016, 10:28 PM)Met.Eng. Wrote: Hi Hector


Hi Hector


Hi Hector
try to mix some metco 15 F with your WC-Co powder, %20-25 as good results with WC-Co
And use bont coat under the top coat, my choice is ni5al arc spray under the top coat. What is your blasting mash number? May be try course blasting media for ex 16 grit Wink
Good luck

Hi, thank you very much Vig and Met. Eng.

Met, why the metco 15 F (self fluxing alloy) what are the benefits that have mixing the metco powder with the tungsten carbide, we wining in toughness? Actually, for the arc-spray coat (Carbon steel) we use 16 grit and in HVOF process we use 60 grit.
Reply
10-19-2016, 06:25 PM, (This post was last modified: 10-19-2016, 06:31 PM by Met.Eng..)
#7
RE: HVOF 88 WC-12Co Cracking problem on wire drawing capstan
(10-17-2016, 09:39 PM)Hector Monjardin Wrote:
(10-15-2016, 10:28 PM)Met.Eng. Wrote: Hi Hector


Hi Hector


Hi Hector
try to mix some metco 15 F with your WC-Co powder, %20-25 as good results with WC-Co
And use bont coat under the top coat, my choice is ni5al arc spray under the top coat. What is your blasting mash number? May be try course blasting media for ex 16 grit Wink
Good luck

Hi, thank you very much Vig and Met. Eng.

Met, why the metco 15 F (self fluxing alloy) what are the benefits that have mixing the metco powder with the tungsten carbide, we wining in toughness? Actually, for the arc-spray coat (Carbon steel) we use 16 grit and in HVOF process we use 60 grit.

Yes , toughness and reduce shrink rate , and u will see when u spraing this , the surface temp will lower than pure one for same pass Smile
Reply
10-19-2016, 11:55 PM,
#8
RE: HVOF 88 WC-12Co Cracking problem on wire drawing capstan
(10-19-2016, 06:25 PM)Met.Eng. Wrote:
(10-17-2016, 09:39 PM)Hector Monjardin Wrote:
(10-15-2016, 10:28 PM)Met.Eng. Wrote: Hi Hector


Hi Hector


Hi Hector
try to mix some metco 15 F with your WC-Co powder, %20-25 as good results with WC-Co
And use bont coat under the top coat, my choice is ni5al arc spray under the top coat. What is your blasting mash number? May be try course blasting media for ex 16 grit Wink
Good luck

Hi, thank you very much Vig and Met. Eng.

Met, why the metco 15 F (self fluxing alloy) what are the benefits that have mixing the metco powder with the tungsten carbide, we wining in toughness? Actually, for the arc-spray coat (Carbon steel) we use 16 grit and in HVOF process we use 60 grit.

Yes , toughness and reduce shrink rate , and u will see when u spraing this , the surface temp will lower than pure one for same pass Smile

Thank you very much! Im going to make some samples...

Reply




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