Aluminum composite reportedly stronger, lighter than carbon

On Wed, 10 Oct 2007 15:49:48 -0700, Fred the Red Shirt
wrote:

On Oct 9, 11:53 pm, Steve Hix
wrote:
In article .com,
Fred the Red Shirt wrote:


...

Obviously you have not seen how a telescope mirror ages over the
years.

Guess again.

Well then you should have observed that the transparency increases
between cleanings.


It's easy to recoat the mirror, so it's not so much of a problem,
certainly less of one than dealing with silver corrosion.

While it is not a technologically daunting task, it is not cheap for

IF you have the equipment (vacuum chamber, heater for vaporizing
Aluminum) it's relatively simple. One of our Astronomy club members
does up to 10 or 12" for the locals. IIRC his favorite source of
Aluminum is peeling the foil off gum wrappers although regular
Aluminum foil works. It just takes more power.

It doesn't take a super high vacuum either. Just one high enough to
develop a plasma although that's not part of the process.

On local used the chemical process for coating which worked pretty
well, but the coating isn't nearly as even as vacuum deposition.

larger mirrors especially when you consider shipping. I have a 17.5"
mirror that will need realuminizing when I finally get around to
putting
it into a scope. It has been cleaned exactly once, but the coating
is nearly gone entirely after 30 years in storage.

Offhand, do you know anyone who recoats mirrors that size?

Not that size, but there are a number of labs that do the work and I
think I saw a couple of links listed.

Roger (K8RI).

Richard Riley wrote:
On Thu, 04 Oct 2007 04:52:18 GMT, Darrel Toepfer
wrote:


Ron Wanttaja wrote in
m:


On Wed, 03 Oct 2007 16:35:43 -0700, Richard Riley
wrote:


"Research is continuing to look at fatigue, as well as analysis of
damage caused by corrosion, hail storms and other weather phenomena,
including trucks that collide with aircraft while they’re on the
ground."

That's really bad weather.

When they say, "It's raining cats and dogs," one generally ISN'T
thinking CATerpillars and DOGdges. :-)

Can "transparent aluminum" be far behind?


You're behind the times. Transparent aluminum is commercially
available, I have a sample on my desk. It's expensive - $10/sq. in -
but more bulletproof than armored glass and half the weight. Google
aluminum oxynitride or ALON.

Star Trek 4 came out in 1986. The first patent for aluminum
oxynitride as transparent aluminum - from Raytheon, patent 4720362 -
was filed in 1985 and granted in 1988.

Damit Scotty!

You know the Prime Directive specifically prohibits passing advanced
technology to primitive cultures!!

Richard Riley wrote:

Star Trek 4 came out in 1986. The first patent for aluminum
oxynitride as transparent aluminum - from Raytheon, patent 4720362 -
was filed in 1985 and granted in 1988.

D@rn, but was it formulated on an old Mac with a wired mouse?