Diamalloy 2004 surface roughness problem

[Khairul Anwar]

Greetings to All,

I got a question here, I am using the Diamalloy 2004 powder for my HVOF coating and there is a problem on surface roughness. I am looking for 2.0mRa and below, but getting alomost double of the requirement. Anyone have any idea??
Thanks

[Gordon]

Hi Khairul Anwar

Assume you mean 2 μm Ra for as-sprayed coating.

I would expect around 4 - 6 μm Ra for as-sprayed Diamalloy 2004. I doubt whether you could ever get it to spray finer than 2, in fact I think you would have problems getting any powder to spray finer than 2.

[Lars.Patrick]

Greetings to All,

I got a question here, I am using the Diamalloy 2004 powder for my HVOF coating and there is a problem on surface roughness. I am looking for 2.0mRa and below, but getting alomost double of the requirement. Anyone have any idea??
Thanks

We were able to achieve a 4 μm surface finish with 2004 NS after adjusting our grinding process... I think our coating "as-sprayed" was ~32 μm if I remember correctly, but it also was pretty thick @ 0.040" on an OD (.020" thickness).

The issue we were having looked kinda like pull-out honestly? Almost looked like regions of higher porosity... but not quite...curious if that's what you're encountering?

I ran extensive labs to make sure the spray wasn't the issue and began looking elsewhere.

We figured out that when we got within 0.004" of the final dimension (on a diameter) we needed to step back to taking 4 tenths per pass (0.0004").
Also, we used a 0.05 micron diamond suspension for final polishing.

This seemed to be the fix for us, the issue of "speeds and feeds". Hopefully it will help you as well!

The lapping suspension we use is the what we have in the lab for polishing samples, and we do the final polish by hand.




Assume you mean 2 μm Ra for as-sprayed coating.

I would expect around 4 - 6 μm Ra for as-sprayed Diamalloy 2004. I doubt whether you could ever get it to spray finer than 2, in fact I think you would have problems getting any powder to spray finer than 2.

Regards Gordon