Cracks in WC-12Co coating
06-19-2012, 04:34 PM,
#1
Cracks in WC-12Co coating
Hi, everyone:
I have been working on spraying of WC-12Co coating for quite a long time. However, the cracks(about 0.06-0.07 mm, perpendicular to the interface) are invariably present in the cross-sections when viewed at a magnification of 200. I wonder if the cracks resulted from the spraying process or from metallographic preparation processes?
The coatings are sprayed with a Metco Unicoat model sray system.
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06-19-2012, 09:37 PM,
#2
RE: Cracks in WC-12Co coating
Hi,
if the samples preparation proceeds with correct way according to ASTM wont see cracks founded.
i think that's happen because a a deferential of thermal expansion between substrate and coat materials
select proper substrate with near thermal expansion of coating layer.

Mustafa
Metallurgical Engg.
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06-20-2012, 04:36 AM,
#3
RE: Cracks in WC-12Co coating
Dr Tofi:
What do you mean by "sample preparation"? the spray or the metallographic preparation? What's the ASTM document?
It is required the coating be sprayed on a titanium alloy.
Thank you!
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07-19-2012, 04:25 PM, (This post was last modified: 07-19-2012, 04:42 PM by Ken59.)
#4
RE: Cracks in WC-12Co coating
(06-20-2012, 04:36 AM)fhyuan Wrote: Dr Tofi:
What do you mean by "sample preparation"? the spray or the metallographic preparation? What's the ASTM document?
It is required the coating be sprayed on a titanium alloy.
Thank you!


Hi
You can stop the cracking by with a thin layer of 5-10 mil of Ni/Cr only (80/20) on the base and the then spray the WC-12. Plus cool the part down slow,and leaving it in the spray lathe at about the same RPMs. but I was using Hvof to spray parts.
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07-26-2012, 04:09 PM,
#5
RE: Cracks in WC-12Co coating
Hi, the drawing has it that the coating be plasma sprayed directly onto a titanium alloy substrate.
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