Temperature HVOF Process

[ir_minja]

Hi Gordon,

When i'm using WC-Co 88% 12% on coated surface by HVOF process, what is allowable maximum temperature on the surface coated before adding another coated layer (to avoid hot stresses)?

And how about other alloys that can be coat by HVOF, i.e:

1. Hastelloy C
2. Stellite 6
3. Stellite 1
4. Colmonoy 6
5. WC-Co-Cr
6. SS 316

Regards,
~Minja

[Met.Eng.]

Hi Minja

more than approximately 205 degrees celsius heat is not required.

The temperature during spraying should not exceed 205 C "Product Process Suport 2005 METCO"

On the other hand, Coating thickness is difficult to keep under control with increasing temperature. I think that such an operation can be done in accordance with the material properties.

[Gordon]

Hi Minja

As Metallurgy_eng said ~ 200C is generally the maximum recommended coating/part temperature during spraying for ferrous type substrates. So you need to get some idea of the temperature rise caused by a pass of the gun to know the safe surface temperature in which to continue spraying.

'To avoid hot stresses' I think it is more important to think about deposit thickness per pass. Aim to build-up coating in very thin layers (ideally around 0.0002" or 5 um), this will help in controlling distribution of heat. Ideally, try and set-up process so that spraying is continuous and that part/coating temperature remains fairly constant through out. I know, easier said then done , but that should be your goal.