I have never seen an epoxy that will work to 500 deg F ... the limit from
what I have seen is approx 450 deg F and even that is pushing it. However
whilst some epoxies are claimed to be able to have Tg's of 350-450 F it is
not quite that simple. I know because I am working with these adhesives on a
current project ... in fact I have just had a series of Tg tests run non 4
different epoxies and the results were surprising. The issue is that you can
only achieve the high Tg numbers quoted by a very careful and usually very
complex post cure heating cycle. A homebuilder would never achieve this.
With a simple post cure (i.e. ramp up, hold, ramp down) some of the resins
with more modest Tg values will perform a lot better ... actually the Tg
numbers you will get from these resins will surpass those for the the resins
which claim higher Tg values.


"Ryan Young" wrote in message
om...
(Ryan Young) wrote in message
. com...

These angles are bolted and epoxied to the side of the magnesium case.
My point: what good is the epoxy?

I had further conversation with Scott Casler.
================================================== ===
Hi

I use a epoxy that is similar to JB Weld.

Scott ( Hummel Engines)
----- Original Message -----
From: ryoung@
To: humeng@
Sent: Monday, September 13, 2004 3:24 PM
Subject: What Epoxy do you use?


To bond the aluminum angles to the side of the magnesium case?

Thanx for your previous reply to my inquiries.

Ryan Young
Ultracruiser Plus Builder

================================================== ==

From the JB Weld web site:

Properties (lbs/psi)
Tensile Strength: 3960
Adhesion: 1800
Flex Strength: 7320
Tensile Lap Shear: 1040
Shrinkage: 0.0%
Resistant to 500º F

I'm not sure what "Resistant" means in this context. JB Weld is a
steel-filled epoxy adhesive. Belzona is much the same stuff, and I'm
intimately familar with both of them. Devcon is another brand, and
they have both the widest variety and the best technical information:

http://www.devcon.com/techinfo/107.pdf Aluminum filled epoxy.
Temperature Resistance Wet: 120°F; Dry: 250°F
Adhesive Tensile Shear 2,600 psi
Compressive Strength 8,420 psi
Modulus of Elasticity 8.0 psi x 10(5) in.
Flexural Strength 6,760 psi
Coefficient of Thermal Expansion 29 [(in.)/(in). x °F)] x 10(-6)

Wowee Kazowee, look how much it expands! Twice as much as aluminum or
magnesium!

http://www.devcon.com/techinfo/101.pdf Steel filled epoxy putty, more
like JB Weld
Adhesive Tensile Shear 2800 psi
Compressive Strength 8260 psi
Modulus of Elasticity 8.5 x 10(5) psi
Flexural Strength 5600 psi
Coefficient of Thermal Expansion 48 [(in)/(in) x °F)] x 10(-6)
Even more expansive, and not much stronger.

Application instructions which cut pretty close to Hummel's plans:
1. Thoroughly clean the surface with Devcon® Cleaner Blend 300 to
remove all oil, grease, and dirt. This is probably a detergent - RRY
2. Grit blast surface area with 8-40 mesh grit, or grind with a coarse
wheel or abrasive disc pad, to create increased surface area for
better adhesion
3. Clean surface again with Cleaner Blend 300 to remove all traces of
oil, grease, dust, or other foreign substances from the grit blasting.
4. Repair surface as soon as possible to eliminate any changes or
surface contaminants.