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I'm trying to make a Bismuth-Indium based low-melt alloy wetter (specifically, better at wetting to solid metals and glass). I've tried adding gallium, which obviously works, but due to its metal-attacking nature it can't be used here.

I know that antimony and tellurium are often used as surfactants, but I've only read of them acting as surfactants in organic solvents, and can't find anything on whether alloying them with a liquid metal would improve its wetting ability. As I don't have any Sb/Te at present, I'd rather ask if this has any chance of helping before trying them.

If not, is there anything else I could incorporate into the alloy - possibly a non-metal/metalloid - which would improve wetting?

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    $\begingroup$ I don't believe Sb and Te can act as surfactants in organic solvents. What you have read must have related to metal alloys. $\endgroup$
    – Ivan Neretin
    Commented Oct 24, 2018 at 10:28
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    $\begingroup$ Be careful with tellurium. I have heard in ( highly recommended ) the Episodic Table of Elements podcast, that Ingesting tellurium, or even holding it in your hand for a quick second, will cause your breath and body odor to reek with a somewhat garlicky smell that is guaranteed to repel vampires — and anyone else who crosses your path, too. The body metabolizes this element into the extremely pungent dimethyl telluride. .... it will generate breath so foul that birds will fall from the sky, the city gates will be closed, and new widows will weep. $\endgroup$
    – Poutnik
    Commented Oct 1, 2021 at 9:11

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The surface of glass has many Si-O-H and Si-O-Si bonds; deeper inside would be Na and Ca and Al. An active metal might engage those surface atoms. Na might be too reactive (forming a dross of NaOH on the surface of your alloy, or reacting with water at the glass surface). Aluminum or zinc or perhaps magnesium might be active enough to contribute some sort of adhesion to glass.

Tin oxide is bound to glass surfaces for electrical conductivity. Perhaps it could be an intermediate layer, bonding glass and your alloy. And silver is deposited on glass to make mirrors. Your alloy might well stick to a silver deposit. So, while this doesn't actually make your alloy wetter, it could solve your problem of adhering to glass.

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    $\begingroup$ Titanium and chrome are great sticking layers onto glass. Of course, that just changes the wetting problem to a different interface... $\endgroup$
    – Jon Custer
    Commented Jan 14, 2019 at 17:19
  • $\begingroup$ Silver can wet glass directly but is usually applied via a chemical reaction depositing silver on the glass surface. Modern silvering processes improve this by pre-treating the glass with chemically deposited tin. $\endgroup$
    – matt_black
    Commented Oct 6, 2020 at 11:54
  • $\begingroup$ If I remember correctly, thermometers that use galinstan alloy as the fill liquid, in place of mercury, use a tin oxide coating on the inside capillary surface, to prevent wetting. $\endgroup$
    – Ed V
    Commented Jun 2, 2021 at 20:27
  • $\begingroup$ @EdV Tin oxide may be an alternative to gallium oxide the corresponding wikipedia entry mentions to prevent wetting. Interesting entry, both for the crosslink as (potential) application of this material for liquid mirrors as well as anode in brilliant microfocus X-ray tubes. $\endgroup$
    – Buttonwood
    Commented Sep 30, 2021 at 21:10
  • $\begingroup$ @Buttonwood Ah, thanks for the correction! I had not seen that linked wikipedia entry or the applications beyond thermometry. $\endgroup$
    – Ed V
    Commented Sep 30, 2021 at 21:20

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