Diificulty in getting <1% porosity on a DJ2600 hybrid

[Intel55]

Is it possible to consistently achieve <1% porosity using a dj2600 hybrid spraying 86/10/4 wc-co-cr (45+15)?

using hydrogen.

anyone have parameters?

[Gordon]

Hi Intel55

Yes, you should be able to, but it will depend very much on which powder you use. (45+15) unfortunately is very limited information on your powder, as it does not tell you the particle size distribution, only the range. I've tested powders with the same composition and size range (claimed by supplier) from various suppliers under identical conditions and it is quite staggering the differences obtained in coating quality and deposit efficiencies.

I can only suggest that you use a Sulzer Metco powder specifically designed for the equipment like Diamalloy 5844 using recommended parameters and use this as a bench mark to compare other powders.

[Intel55]

Thanks for the info. I was not even thinking along the lines of the powder size distribution. Good point, need to add that in
Powders used are all from Starck or PAC.

Hi Intel55

Yes, you should be able to, but it will depend very much on which powder you use. (45+15) unfortunately is very limited information on your powder, as it does not tell you the particle size distribution, only the range. I've tested powders with the same composition and size range (claimed by supplier) from various suppliers under identical conditions and it is quite staggering the differences obtained in coating quality and deposit efficiencies.

I can only suggest that you use a Sulzer Metco powder specifically designed for the equipment like Diamalloy 5844 using recommended parameters and use this as a bench mark to compare other powders.

[Gordon]

Hi Intel55

I'm not suggesting that you should always use materials recommended by your equipment supplier/manufacturer, but to take a lot of care when trying an alternative. Example: spent a week of hard work developing a coating for a specific application. Aim to produce coating of best quality, highest deposit efficiency, highest spray rate and at cheapest cost. Six or so powders were chosen for testing including equipment supplier recommended ones. All these powders basically appeared to be very similar in composition and particle size range, but resulting coatings/process showed large variations. Fortunately, one powder was shown to be a clear winner. Some of the powders showed slightly differing coating qualities. Big differences were shown in deposit efficiency, the poor ones would have required 2-3 times more powder to complete the same job (before any tests on increasing spray rate). The equipment recommended powder proved to be good, but did not win on grounds of powder cost (no surprise there then ).

Basically, I would choose the equipment manufacturers recommended powders (or those specified by your customer), if you are not able or afford to first do comparative testing. A cheaper powder may not provide a cheaper coating even when quality issues are not considered. Also, a powder proved to be good with say the JP5000 will not necessarily prove good with the DJ and visa versa.