Stripping for Metco 81vf-ns

[Varela]

Hi Everybody.

Let me introduce myself, I am Gabriel Varela and I am from Mexico.

Right now, I am working in an Aerospace company.

I am look for the best possible stripping method for Metco 81VF-NS plasma spray. I have been trying with "glass bead" and it is going well, but I want to know if there is a better stripping solution because the area where we want to remove the coating is critical.

: Thank you and so sorry for my english!

[Varela]

nobody??

[Gordon]

Hi Varela

to the Surface Engineering Forum.

Not knowing substrate material, part geometry etc. makes it difficult.

Chemical strip methods appear limited as chemicals that attack this coating tend also to attack most substrates. Electrolytic methods may be worth looking at, the one mention later on in this thread Methods-for-removal-of-W-Ni-and-V-coating is said to be suitable for removal of chromium carbide/nickel chromium coatings on many steel, nickel, titanium and aluminium alloy substrates.

High pressure water jet or dry ice blasting. grit/shot blasting, machining, grinding, hammer and chisel are other mechanical methods to consider. Which is better depends on your particular requirements.

[MichiganMan]

If your substrate and the coating material have much different coefficients of thermal expansion, and the workpiece is rigid enough you could try heating the offending area with a propane torch (until cherry red), then giving it a good smack with a hammer.

Based on your post I would assume that abrasive blasting equipment is readily available to you. If you want to give blasting another go, then I would suggest using coarse (16 grit or so) aluminum oxide for stripping by abrasive blasting. The Al2O3 is far more aggressive than glass bead, and at higher pressures it can chew through about anything. If the substrate is remotely as hard as the coating, then you may want to try to blast at a somewhat acute angle to the coating edge. This can in some cases this can undermine the coating and cut the strip time in about half. That said, be very careful not to erode too much of the substrate if the coating is coming off difficult.

[joanwang]

Metco 81VF-NS is hard coating, electroplate solution or machining is suggested to remove it. Grit blasting maybe accessorialy needed . I have tried high pressure water jet to strip it,but it's too hard to split off the coating with water pressure goes up to 3500bar.No further test proceed for consideration of substrate material safety.

[LEN WOOD]

There are Aerospace Standard Practice procedures (PWA, RR etc) for stripping/softening of 81 VF-NS & '-NS on combustion liners and cans. The procedure enables the coating to be easily and safely removed by blasting. I'll try to dig it out.