Radiation material properties- absortancy

[geodesia]

Hi all,
I am performing some calcualtions to consider solar radiation in temperature for an structure, and I would need the values for absortancy for that.
For (landa) aprox. 0.5 micrometers (solar radiation) and (landa) aprox 10 micrometers (low temperature)

The structure will be plain carbon steel, but painting with a polyurethane, 75 microns. The final colour is RAL 7010, that is a kind of grey. In order to evaluate several possibilities, I would need the data considering light grey and dark grey.


I have found some other data, but not for the finishing/colour I need.

I know there is a book called "thermal radiation properties survey" Gubareff, G.G.; J.E. Janssen and E.H.Torbog, and maybe is there...can anybody give me these values?

Thanks in advance

 

[IRstuff]

There are a few tables available on the web:

http://www.infrared-thermography.com/material-1.htm

http://www.electro-optical.com/html/bb_rad/emissivity/matlemisivty.asp

TTFN

FAQ731-376

 

[geodesia]

Thanks for the info...but I only find data for long wave, not for short as needed for solar radiation...any help?

 

[tkordyban]

Absorptance of radiation is not a material property, it is a characteristic of the surface. So it doesn't matter if the substrate is steeel or aluminum or plastic. In your case what matters is the paint, and the texture of the paint. To get its radiation properties you should contact the paint manufacturer.

Here is a hint for gray paint -- it usually has the same absorptance for all wavelengths, solar and infrared. But if want to be sure, you need wavelength-dependent data from the manufacturer or a test lab. Materials differ from one vendor to another, and the final texture can make a difference.