[time-nuts] OCXO housings - Why copper and not iron/steel?

[Dave Daniel]

Heat capacity is essentially a measure of how much heat a material can hold (to a first approximation). Thermal conductivity is a measure of how well a material moves heat between two different temperatures mechanically connected to the material. When using a material as a heat sink, one wants to transfer the heat from the device being cooled to the (presumably cooler) ambient environment as quickly as possible, so thermal conductivity is more important than heat capacity for that application.

Note that a “heat sink” may also be used to warm up a cold material (e.g., reverse heat flow). A trivial example of this is that if you want to quickly defrost a piece of food, lay it on a good thermally conductive  surface such as a large aluminum or copper pan or tray. The food will defrost quickly because one is moving heat from the ambient environment into the food more quickly than if the food is just sitting on one’s countertop.

DaveD

> On Oct 30, 2020, at 18:23, Attila Kinali <attila at kinali.ch> wrote:
> 
> On Fri, 30 Oct 2020 17:58:24 -0400
> Bob kb8tq <kb8tq at n1k.org> wrote:
> 
>> Simple answer: conductivity. You don’t get much heat capacity either way.
> 
> Ah.. so it is more important to have less temperature gradients
> than having high capacity?
> 
>            Attila Kinali
> 
> -- 
> <JaberWorky>    The bad part of Zurich is where the degenerates
>                throw DARK chocolate at you.
> 
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