Posted by Gordon England on February 23, 2004 at 23:49:33:
In Reply to: Tungsten Carbide posted by Chris on February 20, 2004 at 07:32:11:
: Dear Sir,
: What is the maximum build up possible while coating Tungsten Carbide with Plasma spray process & also with HVOF. What would be the coating properties ?
: Thanx
: Chris
Hi Chris
The thickest tungsten carbide based coating I have come across is about 6 mm for a top end HVOF coating of WC/17Co. This case is not typical for most of the other coating types though.
Most tungsten carbide based coatings are rarely applied to thicker than 0.25 - 0.5 mm which is where the thickness limit generally lies for plasma sprayed coatings. HVOF tends to be a little more tolerant.
Thicker coatings as aposed to thinner coatings tend to acquire higher levels of residual stress, lower bond strength and reduced support from the substrate, apart from being more costly. It is generally best by design to go for the thinner coatings, but in cases where dimension restoration is needed, it is possible to use a less stressful intermediate coating to take the brunt of the build-up. The only case where very thick carbide coatings are possibly needed is where the acceptable wear allowance is similar to the coating thickness.
Regards Gordon
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