Tungsten Carbide coating

[Guna]

Hi everyone,
I understand that that WC based coatings is to be used in the environment where the temperature is to be below 500'C. Is it because of decarburization or oxidation which make the coating fails?
2nd, In HVOF process e.g Dj2600 how the decarburization is minimized/eliminated where the powders are fed into combustion chamber which is around 2000'C or more?. Do the combustion melt Cobalt only and what transformation takes place for WC?
By the way practically I get good coating, just want to know what happens and explained theoritically.

Thank you

[Gordon]

Hi Guna

I understand that that WC based coatings is to be used in the environment where the temperature is to be below 500'C. Is it because of decarburization or oxidation which make the coating fails?

Yes

2nd, In HVOF process e.g Dj2600 how the decarburization is minimized/eliminated where the powders are fed into combustion chamber which is around 2000'C or more?. Do the combustion melt Cobalt only and what transformation takes place for WC?

Ideally, the particles are heated just enough to allow splatting on impact (not necessarily melting) and not high enough to cause reaction/alloying between WC and cobalt or oxidation/decarburisation. Fortunately, HVOF's very high velocity limits the particles dwell/heating time dramatically and allows use some control when using suitably sized particles.

details-on-hvof-t-1013.html