Posted by Gordon England (62.252.0.12) on 13:42:08 28/02/05
In Reply to:Iron coating surface roughness posted by R. Pittier
: Hi,
:
: this seems to be a very helpful forum and I'd like to start a discussion on the following topics:
:
: - how to diminish surface roughness when plasma-spraying iron powder?
: - how to measure an iron coating on an aluminium substrate?
:
: I've been looking for an answer to the latter for a while... Eddy currents and ultrasonic measurements obviously don't work well because of the surface roughness (substrate thickness = 6-8 mm, coating thickness = 0.2-1 mm, roughness = 50-100 um), but I'm sure there IS a solution... I can't be the only one having this problem...
: I've been starting testings for the first question by varying the iron powder particle size and I'm waiting for the results. Is it the right parameter to work with?
:
: Thanks
:
: RP
Powder particle size will have probablly the largest effect on coating texture. The grit blast roughness can also be a factor on thin coatings.
Plasma spraying parameters can also effect texture, usually higher velocity produces finer texture.
Instruments based on eddy current are usually use for this type of coating/substrate combination. Magnetic type instruments if calibrated may be possible, although they are normally used for the reverse coating/substate combination.
Regards Gordon
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