HVOF porosity
11-13-2016, 09:23 AM, (This post was last modified: 11-14-2016, 06:38 AM by sprayloud.)
#1
HVOF porosity
Hey all,
I would like to ask you about the possible causes of HVOF WC/Co having unusually high porosity levels (~20%). Could it be spray parameters, powder choice, gun specific problems, all of the above ?


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11-13-2016, 12:22 PM,
#2
RE: HVOF porosity
(11-13-2016, 09:23 AM)Corund Wrote: Hey all,
I would like to ask you about the possible causes of HVOF WC/Co having unusually high porosity levels (~20%). Could it be spray parameters, powder choice, gun specific problems, all of the above ?

There may be several errors, but without pictures (microscopy of the cross-section of the layer and photo of the flame with powder) is difficult to say anything.
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11-14-2016, 06:39 AM,
#3
RE: HVOF porosity
(11-13-2016, 12:22 PM)Vadim Verlotski Wrote:
(11-13-2016, 09:23 AM)Corund Wrote: Hey all,
I would like to ask you about the possible causes of HVOF WC/Co having unusually high porosity levels (~20%). Could it be spray parameters, powder choice, gun specific problems, all of the above ?

There may be several errors, but without pictures (microscopy of the cross-section of the layer and photo of the flame with powder) is difficult to say anything.

I'v added the cross section of the layer. Any ideas ?
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11-14-2016, 08:10 AM,
#4
RE: HVOF porosity
Hi Corund,
At first glance the burner parameters were too hot and too slow. Which burner and what parameters do you use? It is also important to measure the spray distance and the grain size of the powder. If the parameters are too hot, try to use a slightly coarser powder with a slightly higher spray distance.
Regards
Vadim
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11-28-2016, 02:27 PM,
#5
RE: HVOF porosity
Hi,
What material is the substrate made of?
There are many visible issues within the Images you posted in my opinion.
Coating structure doesn t appear to be wc/co
Coating is detached from substrate which is very unlikely for an hvof coating
Substrate appear to have been contaminated from a prior different coating (most likely a ceramic)
Lab preparation of samples might be wrong

My 2 cents
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