Questions about making galinstan

[artis]

Hi, I have the 3 essential metals needed to make galinstan, namely Gallium , Indium and tin, I also read the typical proportions percentage wise that each of the elements must have for given weight of final mixture.
The quoted percentages are 68.5% Ga, 21.5% In, and 10.0% Sn by weight,

my question is what changes in the final mixture if those parts are mixed in differently , I would assume the melting point either goes up or down , etc,
also what extra additives would be necessary to make the melting point lower or maybe increase the non wetting properties?

Basically any good insight would be appreciated.
thanks.

 

[Borek]

The information you are looking for is a phase diagram for the eutectic mixture.

Yes, if you don't hit the exact composition, melting point will be higher. Additives will change the melting temperature as well.

Technically it should be possible to start with any composition - when you slowly cool it down some of the mixture will solidify, and the remaining liquid will have its composition closer and close to the eutectic. At some point you should have just the liquid eutectic mixed with solids that - at least in theory - can be separated. That will be very difficult, as keeping everything in a constant temperature during such operation is quite a challenge.

 

[artis]

I made at home some 150 grams of galinstan in the proportions given over in the internet.
My mixture stays liquid at room temp, so I suppose I have done everything correctly, although there is a disappointment , it seems like the galinstan mixture has rather good adhesion to many surfaces , in other words it wets to surfaces such as ceramic, glass, stainless steel etc.
I have worked with mercury before and mercury was perfect in this regard, it was always very smooth and never wet any surface ,

now does galinstan does this or is it just that commercial high grade galinstan has some extra additives that make it less adhesive and less wetting to surfaces?

 

[TeethWhitener]

now does galinstan does this or is it just that commercial high grade galinstan has some extra additives that make it less adhesive and less wetting to surfaces?

Yes galinstan wets glass. Mercury doesn’t, mainly because of its insanely high surface energy (in other words, air wets glass more effectively than mercury does).

 

[snorkack]

Yes galinstan wets glass. Mercury doesn’t, mainly because of its insanely high surface energy (in other words, air wets glass more effectively than mercury does).

It is alleged that it is more because of the inertness of mercury. When oxygen is thoroughly excluded, galinstan does become less adhesive.
In presence of air, surfaces which galinstan does not wet are said to include teflon and graphite.

 

[TeethWhitener]

It is alleged that it is more because of the inertness of mercury.

The two aren’t mutually exclusive. Contact angle is determined by Young’s equation. The surface energy terms in that equation are determined by the microscopic details of the surfaces.

It’s not particularly surprising that galinstan doesn’t wet Teflon (I’ve never tried), but I know for a fact that galinstan will wet graphene (graphite’s surface energy can behave differently from graphene).

 

[artis]

well since I have some galinstan I can try the trick with graphite from commutator brushes and see what happens

 

[jim mcnamara]

Yup. That is how you do it. You may want to buy one of those tiny "squirt" bottles of graphite that is used lubricate exterior keyholes, e.g., automobiles. That way, you reduce potential contamination. Cheaply.

 

[chemisttree]

You might consider silanizing the glassware to see if that treatment would work.