THERMAL GLUE/PASTE uses in stirling engines?

[Chriske]

Although I hardly use it myself I suggest using Loctite. Some types can withstand high temperatures.
The only reason I use it myself is to secure ball-bearings.

[Chriske]

Google is your friend...;-))

Loctite : 510 - 121078 - 3479

[Chriske]

Vamoose,

I understand your concern, but do not understand why you mentioned water, air and concrete in your list. These items are not used while building engines.
Coefficient of thermal expansion you say, yes indeed there might be a problem but in most cases it will not cause problems at all. For instance when I want to secure a steel ball-bearing into an aluminum holder. The difference in coefficient of thermal expansion is rather large but will not cause problems because in most cases ball-bearings are not used close to a heat source, so there is no expansion.
When I have to secure, I already mentioned it higher up, something close to a heat source I'll never use glue. I'll use rubber sealings instead. Best choice imo.


Chris

[Ian S C]

I'v been using Loxeal 8321 high stength, high temp shaft retainer (similar to loctite shaft lock) for attaching the cold end of displacers, attaching the stainless displacer cap to the motor, and the Heylandt Crown/hot cap, to the hot piston on an ALPHA motor. Ian S C

[vamoose]

Sorry if this topic now appears random. All my posts have been wiped from system and Boyd informs me cant be retrieved...

[Ian S C]

A better Loxeal retainer is 8686, this is rated at 230*C. Ian S C

[vamoose]

I started this topic (before my posts were lost) to see what experiences people have had using adhesives to attach things such as highly corrugated sheets to displacers, hot caps, and cylinder bore walls to increase surface area.
I'm looking for an adhesive that has high heat tolerance and high thermal conductivity greater than that of thermal pastes which peak at about 9W/(m.K). There would be a lot of vibrational and inertial forces to contend with.
Also wondering if people have used different adhesives to attach heat sink type materials onto the outer surface of engine blocks to increase thermal transfer.
The reason I'm considering doing these things, is to reduce the need for milling and machining when experimenting with different designs.
Thanks Chris and Ian for your feedback.
vamoose

[Bumpkin]

I've seen anecdotes that JB weld is a fairly good thermal conductor. No definitive numbers though. The standard formula is rated for 500 F. (260 C.) I used it successfully on broken motorcycle cooling fins and side covers, even built up a portion and drilled and tapped it. I didn't torque that bolt too tight, but it held.

[Ian S C]

Thought this might be the place for this question. Chriske, how do you attach test tube displacers to the rod, and how do you attach test tube displacer cylinders to the cold end of the motor, I'v got a chap on the model engineer web site, wondering how to attach/glue glass to metal. Ian S C

[vamoose]

Sorry Ian, I cant help with your query. Although I'm interested in the answer, and am sure that there are plenty of experienced people on the subject, that might help fill us in.

But,
I would like to add, in regards to thermal pastes/glues/grease's,
One of the aspects of these compounds that I overlooked when initially inquiring about their properties, was the fact that they are primarily designed to be used on electronic components.
Thus, they are required to be thermally conductive, whilst still being electrically non conductive,
and these two apparently opposing requirements can be, to some degree, mutually exclusive. Hence the relatively low levels of thermal conductivity of these compounds.
So, if one wishes to to optimise the 'thermal contact conductance' between different materials, then the use of these 'electronics' oriented glues and pastes as an interface medium, probably isn't ideal.
vamoose

[Ian S C]

Vamoose, I don't think thermal connection is the thing we'r after here, it's the mechanical attachment. I personaly would make a metal collar to fit over the test tube that would bolt up to the metal of the cold end, with an o-ring in between, but Chriske may have some other method, or refinement. Also he may havea sggestion as to what sort of sealer, ie., silicon , or something, or a loctite number. Ian S C

[vamoose]

Actually it was a poorly written post on my behalf Ian, it was meant as a separate statement and not as a direct response to the subject you raised. I should have put it in a seperate posting. It was a point I meant to make ages ago, but forgot to do so...
vamoose

[Ian S C]

No worry, I under stood that. I have tried conductive silicon heat sink (electronics)paist on heat sinks on hot air engines. Ian S C

[vamoose]

I recently had to attach a rear view mirror to my front windscreen.
I bought a glue from my local car parts joint that was specifically designed to attach the metal lug of the mirror to the glass windscreen.
It was fairly expensive but did the job (it definitely made a extremely strong bond). I'm not sure how it would stand up to the possible heat of a Stirling engine though.
There are many different brands of these metal - to glass - adhesives avaliable on ebay...
http://www.ebay.com.au/sch/i.html?_sop= ... =200&rt=nc
maybe they could be usable for stirling engines?
vamoose