Thick insulating coating Al2O3 - APS 9MB

[Binhngo]

Hello admins and forum members, 
I have been following the topics for a long time and learned a lot of useful knowledge for myself.
Today I have a problem that I really need your help with:
i need to make alumina insulating coating using APS with a gun 9MB, the finished size after grinding needs to reach 130mm in diameter. Alumina coating thickness need 0.5-0.7mm.
However, there is a problem that the size after being worn is only 127.4mm, which means it has been worn 1.3 mm in depth.
I'm thinking 0.8mm NiAl95/5 + 0.5mm Al2O3. Or 0.8 NiCr80/20 + 0.5 Al2O3.
Looking forward to your advice in this case.

Thank you.

[Vadim Verlotski]

Dear Binhngo,
you should take into account that the thicker the coating, the greater the risk of chipping. Since the ceramic layer is weaker than the metal layer, it is better to gain the missing thickness with metal. You have decided this completely correctly.
As for the choice between nichrome and nickel-aluminum, it is better to choose Ni-Al, since the adhesion to steel and the cohesion of nickel-aluminum is higher than that of nichrome and ceramics is held on it more firmly.

[Binhngo]

Dear Binhngo,
you should take into account that the thicker the coating, the greater the risk of chipping. Since the ceramic layer is weaker than the metal layer, it is better to gain the missing thickness with metal. You have decided this completely correctly.
As for the choice between nichrome and nickel-aluminum, it is better to choose Ni-Al, since the adhesion to steel and the cohesion of nickel-aluminum is higher than that of nichrome and ceramics is held on it more firmly.

Thanks a lot for the helpful advice, Vadim Verlotski 

[Stephen Booth]

good information