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Thermal conductivity of ATH


By TomG, Section Mechanical
Posted on Thu May 15th, 2008 at 10:26:04 PM MST
Anyone know it?

Does anyone know the actual thermal conductivity of Alumina Trihydrate, even vaguely? I've been searching all over the web, but even technical papers seem to just refer to it having "high thermal conductivity", which isn't very helpful.

Thanks,
Tom

This has absolutely nothing to do with "Wind" so resectioned to "Mechanical" where it belongs. [questions about construction methods and materials]
Thermal conductivity of ATH | 6 comments (6 topical, 0 editorial)

Re: Thermal conductivity of ATH (3.00 / 0) (#1)
by scottsAI (user name at eml dot cc) on Thu May 15th, 2008 at 07:02:08 PM MST
(User Info)

Not sure of TomG application, ATH has been discussed here as an additive to epoxy to make stators. Claim is high thermal conductivity... as above.
Much searching no data, rather strange.

Have fun,
Scott.



Re: Thermal conductivity of ATH (3.00 / 0) (#2)
by DanG on Thu May 15th, 2008 at 07:37:33 PM MST
(User Info)

ATH or Aluminum Hydroxide has a Specific Density of 2.4g/cc - the way it is normally used as a sorted-to-nanometer-sized-powder precludes it acting as a conductor on it's own - yet when added to a resin like Vinyl-Ester (Specific Density from .95 to 1.6) it could be measured, but it would be dependent on the batch formulation.

One thing noted when searching is a property of absorbing infrared heat - being a poor emitter of IR, that's the only minus side of it I could find. It is also an ingredient in insulating paints along with Aluminum Sulfate and fumed silica (silica spheres, etc.) which is not a good sign except the paint is nearer a clay thats troweled on then a fluid that conforms to a mold.



Re: Thermal conductivity of ATH (3.00 / 0) (#3)
by NukeManSoon on Thu May 15th, 2008 at 08:29:31 PM MST
(User Info)

What is keeping you from deriving it yourself? Make a small cylindrical mold. Use substances with a known thermal conductivity for end caps. pour some hot water in there with a thermometer to measure the inner temperature while you use an infrared thermometer to measure the outer wall temperature. If you know the total heat tranfered out of the system which you can determine by taking the hot water's initial temperature then taking the temperature an hour later. you can then calculate your btu's/hr. just make sure the water for both tests goes into the mold at the same temperature. Use the equation

Total heat transfered= (thermal conductivity x Area x Differential Temperature)/ Wall thickness.

Total heat transfered is determined by seeing how many btu's/hr are transfered out of the system in a given amount of time.



Re: Thermal conductivity of ATH (3.00 / 0) (#4)
by TomG on Fri May 16th, 2008 at 06:25:10 AM MST
(User Info)

the way it is normally used as a sorted-to-nanometer-sized-powder precludes it acting as a conductor on it's own

The same could be said of many fillers, yet I've been able to find TCs for others. If nothing else, ATH occurs as a mineral (Gibbsite), so the TC of that could be given, to compare with quartz, marble, sand/sandstone, and other fillers which are powdered before use.

It is also an ingredient in insulating paints along with Aluminum Sulfate and fumed silica (silica spheres, etc.) which is not a good sign except the paint is nearer a clay thats troweled on then a fluid that conforms to a mold.

I think it's used as a fire retardant in many applications, where its high TC is a drawback rather than benefit.

What is keeping you from deriving it yourself?

Lazyness, not having any ATH to hand, and the belief that

    surely
someone already knows it! :)


Re: Thermal conductivity of ATH (3.00 / 0) (#5)
by NukeManSoon on Fri May 16th, 2008 at 10:34:33 AM MST
(User Info)

I think that doing the experiment would be benefitial. I know that at the nuclear power plant I work at we have theory to practice all the time, where someone with a 30 pound brain designs something and we put it to the test. Often with different results than 30 pound brain guy designed. I think it would give you a good feel how much heat it can pull away from windings in a stator. Maybe I will do it and then let you know my results.


Re: Thermal conductivity of ATH (3.00 / 0) (#6)
by scottsAI (user name at eml dot cc) on Mon May 19th, 2008 at 04:50:47 PM MST
(User Info)

Hello NukeManSoonm

Interested in testing it with alumina? Sand blasting stuff.
Al oxide thermo conductivity is 30-40 we have its numbers.

Packed alumina with epoxy binder should result in 3.2 thermo conductivity.
10x better than epoxy.

Have fun,
Scott.


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Thermal conductivity of ATH | 6 comments (6 topical, 0 editorial)
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