Thermal spray bible!

[TurbineRepair]

Hi all,

I'm quite new to thermal spraying. Can anyone suggest a good book that covers the practical application of plasma coating?

I need to understand the effects of feed rates, gas flow rates etc and get an idea how to manipulate them to change coating properties.

Thanks,


Jim

[Gordon]

Hi Jim

to the Surface Engineering Forum.

Well the nearest I got to a bible on plasma spray process when I started out was the "Flame Spray Handbook - Volume III - Plasma Flame Process by H.S. Ingham and A.P. Shepard published by Metco - 1965. Yes I know, stuck in the past etc. but its nice to see how things were done in the olden days and most is still relevant today. I would recommend trying to get all 3 volumes to the Metco Flame Spray Handbook and balance this with a modern day book, which I'm sure other members will help out with suggestions.

Quote:I need to understand the effects of feed rates, gas flow rates etc and get an idea how to manipulate them to change coating properties.

Manipulating process parameters is a complex subject, which I don't think many books cover very well. I still think good old practical (get your hands dirty) trial and error type work is best for learning about this type of stuff

Apart from books, I think you should find this forum a very useful resource and you can always ask the questions books never seem to answer

[TurbineRepair]

Hello Gordon,

Thank you for the information. Our spray system here is quite old so an old book would probably be quite apt! I'll have a look at Amazon later on.
I'm currently sat reading through the A3000 manual, trying to get a better idea of what we are meant to be doing. Worryingly some of it doesn't match what the guys are attempting!
We are looking to set up another spray booth before too long and I've got my eye on that for development work. Should be good for experimenting with parameters/powders etc.

I'm sure more post will follow....

Thanks

Jim

[landemarre]

TurbineRepair Wrote:Hello Gordon,

Thank you for the information. Our spray system here is quite old so an old book would probably be quite apt! I'll have a look at Amazon later on.
I'm currently sat reading through the A3000 manual, trying to get a better idea of what we are meant to be doing. Worryingly some of it doesn't match what the guys are attempting!
We are looking to set up another spray booth before too long and I've got my eye on that for development work. Should be good for experimenting with parameters/powders etc.

I'm sure more post will follow....

Thanks

Jim

Hello Jim

Your question is not easy, there is a lot of parameters.
For a start on plasma spraying with a radial powder injection, start with flow of Argon, Hydrogen and powder gas injection.
Most important Argon flow there is, more particle have fast speed, but less hot they will be. Alone without hydrogen probably you will never be able to made coating except very low melting point materials like Zn or very specific material like Ti, because Argon have very low thermal conduction. So you need add Hydrogen that have an high thermal conduction so powder can be melt, on F4 gun generally you not need have more 25% of Hydrogen in gas Argon - Hydrogen mixture and you have generally a good efficiency near 18%.
Now you have powder gas injection, most often it's Argon, first if you use an F4 gun you should choice your injector in this case there is 2mm, 1,8mm and 1,5mm diameter. Generally I use 1.5 for ceramic powder and 1.8 for metallic powder and I put my injector at 90° (possible 105° and 75°). With gas powder you will be able to insert more or less particle in plasma jet, this is too very important for speed and melting particles.
On A3000 you have generally a mass flow-meter 0-10Nl/min, try not use it with less than 2Nl/min it work but it is possible at long time you will have stability process problems due to error on flow-meter, because gas flow is very important on radial plasma spray.

Now this is a compromise, to hot perhaps you will have to much oxide, but not enough you have a bad mechanical properties or a bad output, etc...
A lot of powders have offered parameter's by manufacturers, try by this.

Now good luck.

Olivier

[TurbineRepair]

Hi Olivier,

Thank you for your comment. I think I'm starting to get the idea of this plasma spraying
We have just got our second spray booth up and running so as soon as we get our new 3MB guns in I'm going to run a series of tests and experiments to see what happens, should be fun

Thanks,

Jim