Thermoconductive super-hydrophobic coating of Aluminium

[cyphyus]

Hy,
I am in a team working in the developement of an engine whose core will need a surface treatment on Aluminium (other metals like cupper or a similar specific heat capacity would be possible) that will:
a) maintain the heat transfer capacity of Al and
b)result in a superhydrophobic surface (the liquid used has a contact angle of 180º, which should theoretically make things easy, but in practice it behaves like water).
What I intend to do is to create an epoxi based mixture of metall dust (it seems that rugh surfaces on a microscopic level decline the adherence of liquids) and caranuba wax (treating the named surfaces with caranuba-based wax has given the best results obtaind to date), but I reccon ther is better to be done.
Thanks for help

[djewell]

There are copper-tungsten alloys available which will give excellent heat transfer while maintaining a reasonable amount of wear resistance. You can also get copper coated ceramics. I wonder how well epoxy will hold up inside an engine - not very well I should think.

A better solution might be a thin coating of metal (applied with a thermal spray process, not epoxy) on the aluminum. A thin coating will not impede heat transfer very much, but it can provide the other properties you need.

[cyphyus]

(07-29-2010 09:11 PM)djewell Wrote:  There are copper-tungsten alloys available which will give excellent heat transfer while maintaining a reasonable amount of wear resistance. You can also get copper coated ceramics. I wonder how well epoxy will hold up inside an engine - not very well I should think.

A better solution might be a thin coating of metal (applied with a thermal spray process, not epoxy) on the aluminum. A thin coating will not impede heat transfer very much, but it can provide the other properties you need.

Thank´s a lot for your advice, any other ideas?

[Gordon]

Hi Cyphyus

to the Surface Engineering Forum.

What is the function of the part?

Have you considered PTFE coating?

[cyphyus]

(07-31-2010 05:07 PM)Gordon Wrote:  Hi Cyphyus

to the Surface Engineering Forum.

What is the function of the part?

Have you considered PTFE coating?

Hy, we have done some tests with PTFE but without improvement. I cannot yet describe the function of it, but it won´t suffer any mechanic stress except that of the fluid at high pressure. sorry & thanks

[pulaunias]

diamond is highly thermally conductive and hydrophobic, but costly.

most polymers are not quite thermoconductive (depending on how high you want).

[cyphyus]

(08-03-2010 07:22 AM)pulaunias Wrote:  diamond is highly thermally conductive and hydrophobic, but costly.

most polymers are not quite thermoconductive (depending on how high you want).

Thanks! I think that is an very good idea, I will try to get some diamond dust to mix it with the polymer, theoretically it should maintain the conductivity if the particles are in touch with the metal. I hadn´t thought of that possibility, as soon as I get the parts to be treated & the diamonds, I´ll let you know the results, I hope less than a month time. Thanks again!

[pulaunias]

come back and get us posted.

I remember my ceramics Prof told me diamond has the highest thermal conductivity in all (known) materials.

Initially it came to me that sputter or somehow coat the substrate with diamond-like diamond or sth like that. I am not very sure if diamond/polymer composite will give better results than metal/polymer or not, but worth trying.

[cyphyus]

(08-03-2010 04:28 PM)pulaunias Wrote:  come back and get us posted.

I remember my ceramics Prof told me diamond has the highest thermal conductivity in all (known) materials.

Initially it came to me that sputter or somehow coat the substrate with diamond-like diamond or sth like that. I am not very sure if diamond/polymer composite will give better results than metal/polymer or not, but worth trying.

sure, I am not quite certain about the hydrofobic properties, but they will certainly depend on shape, size and the structure formed by the compound... thanx again