Dear all,
We have 40kW METCO APS system. We are using METCO 3MB-II gun MRN & MCN power supply with controller unit. We deposit 404NS powder over NiAl. We found blisters/un-melted powders after third pass. What could be the probable cause for this phenomenon?
In addition, we found minor pulsation in arc. We use, 4MP-Dual powder feeder unit. This is pretty old system. Temporarily being used. Powder flow rate-95gms/min, I= 500A, Voltage -74v
Kindly tell me the most probable causes for the above problems?
Have you altered the powder feed rate and power control and studied its effects ?
Uneven powder feed can have many causes. One of them - wet powder (YSZ powder are very hygroscopic). In this case, drying and sieving the powder helps before coating (best heating jacket for powder pot).
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