Aluminum nitride due to its thermal conducitvity is an excellent filler for composite materials. Due to nitride ceramics significantly suffers from oxygen and water vapors it should be used with organic hydrophobic liquid.
polydimethylsiloxane liquid as a binder is used now. Are there any more suitable compounds to apply as a binder in thermal grease?
1.Working temperature is 60-90 Celcius degrees;
2. It shouldn't have phase transitions in the range -60...+250 Celcius degrees;
3.Matting surfaces: Aluminum or copper substrate;
4. The highest thermal conductivity value is desired;
5. Constant properties for at least 3-5 years also are desired.
Maybe ethylene glycol would do; i do not know the thermal parameters of PDMS, but at a first glance it seems to comply with the listed requirements.
As an organic binder polyvinil alcohol (PVA) aqua solution maybe used. But if I were you I tried to use an inorganic binder like sodium silicate (glass water) which is hardened with CO2 gas. It is much better for high temperatures.
If the binder must be hydrophobic, the ethylene glycol and PVA may not be OK. The starter mentioned polydimethylsiloxane, which is one kind of silicone oil. There are serveral kinds of silican oils having the similar properities with polydimethylsiloxane, and a lot of them are stable under 300C, also there are some modified silicone oils may meet your requirements.
I could advise you to look thoroughly through the numerous patent descriptions in this area. More likely, you will find a lot of interesting things for yourself that unfortunately you don't know currently. There are many similar products for different applications in the international market now...
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