F4 Injector Holder Deformation

[Artyom]

Hello Dear Friends.

Merry Christmas and Happy New Year!

I need help. I have a struggle with a powder injectors holder on a F4 plasma gun. The holder gets highly deformed during operation, particularly the lower quarter, which goes up and close to a nozzle (upstream)

Holder parameters are: material - nickel plated brass (Cu/Zn, 60/40% wt.), arrangement 75°/90°/105°/90, .

Spray parameters are: NOZZLE 8 mm tungsten lined, Ar 40 lpm, H2 10 lpm, 600 A, power 45 kW, injectors location 12 and 6 o'clock (90° and 90°), distance gauge 8 mm, injector ID 1.8 mm.

The holder sits on the gun body firmly, all tiny screws are tightened well. But during operation the lower quarter (6 o'clock) goes upstream (please see attached photos).

Moreover, the tiny screws have cut the grooves in the front cap, so the distortion force is high.

I have got down to 34 kW (40/8/500) and everything is fine. But this is far away from F4 operation maximum and I need more power for YSZ ceramic TBC.

Maybe someone has encountered a similar problem?

Thanks in advance