Oxidizing Stainless Steel

[eng86]

Hi, I was wondering if it were possible to effectively oxidize stainless steel for the purpose of blocking thermal radiation. (I had heard that oxidizing a material increases its surface emmissivity) Is this worth trying or a waste of time? Anybody have any other ideas about blocking high-temp thermal radiation?
Thanks for your help!

 

[NickE]

Uh?

What you do to the surface depends on what you want your heat sheild to do, and how much you can spend.

What is your temperature range?

(The surface of Stainless steel is already oxidized, its a thin transparent layer of CrO (Funny I forget the valence) thats what makes it stainless.)


Nick
I love materials science!

 

[eng86]

Hey yeah my mind was somewhere else this morning. I actually want a lower emissivity, obviously, (to block the radiation) so forget about previous question. Thanks for the response.

 

[unclesyd]

You can get a little thicker oxide layer on SS with steam/air oxidation. We did this as part of our break in procedure for all SS parts used in part of our process. I'll try to get some more information next week on the process we used.

The emissivity will change. I haven't run across any numbers, but using thoroughly oxidized SS tubes I almost double the outlet temperature of a solar heater I have in my greenhouse.

 

[EdStainless]

If you are dealing with radiant heat transfer then you would want to polish the surface in order to minimize absorption and maximize reflection. If this isn't a structural part you would be better off using multiple layers of very thin stainless foil with a very shinny surface.

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Plymouth Tube

 

[mewhg]

Unclesyd,

I would be interested in hearing about your solar heater. How it works and how the oxidized tubes made a difference.