We get a lot of
questions about compatibility of our black coatings and surface treatments with
various substrates, what is the best choice of blacks, and how they should be
handled. Most of the spectral and
application data is available on- line (or by request to info@aviantechnologies.com), but
here is some potentially useful information.
Avian-DS and –EP blacks
are surface treatments. They are not ‘sprayed on’- they are a treatment of a
metallic surface. Here is some useful information.
1) -DS black
can ONLY be applied to aluminum (alloys 6061 or 1000); this is an etch-anodize
process, similar in many ways to the well known (but no longer available)
Martin Marietta Black. See:www.optics.arizona.edu/optomech/papers/persky%201999.pdf
2) -EP
black can be applied to any metal substrate. This is a so-called 'copper
black', so a layer of copper is electrochemically deposited on the substrate
and then the copper layer is blackened by an oxidative process. –EP black can
be applied to just about anything as long as the copper layer can be in some
way electrochemically deposited.
3) Both of
these surface treatments produce a surface that is dendritic and are extremely
fragile. If the surfaces have to be handled much (if at all) these are probably
not appropriate for the application.
4) Each of the coatings is
electrochemical. We do not do them here but send the parts out to a vendor (two
separate vendors, in fact) for the treatment.
5) Neither of these surface
treatments out-gas. Both have been, to some extent, been space qualified.
Avian Black-S is a coating. It is a
two-part polyurethane that is extremely black over the 250 nm to 20µ range
(much to my surprise- I didn’t think it would be much good in the mid-IR but
some nice folks at U.S. Army Research measured the hemispherical reflectance
out to 20µ and it is still VERY black!). Some other information:
1) Once cured (RT for 3 days or 60°C
for 24 hours), the coating doesn’t out-gas very much at all.
2) While we recommend you spray it
on, we have customers who brush it on and even some who flow coat it on. It
doesn’t take much coating- 2-3 mils is fine- but the sprayed coating is much
more lambertian than if applied other ways.
3) If the coating appears glossy
after drying, you have not agitated Part A enough before mixing the binder. You
REALLY need to assure that all the pigment particles are in suspension!
If you have questions out there about
any of our coatings and materials, please post them here and we’ll be happy to
try to answer them.
