Is there a surfactant that is able to create a stable suspension of Fe-based alloy powder (particle size around 5 µm) in an organic solvent such as hexane, heptane or similar?
Do your dispersed particle possess a charge or hydrophilic groups on the surface? I do not think a surfactant can help (because of inverse phases). How do you disperse the powder? Maybe you should change the dispersion strategy. Strong sonication may well suit for the present case.
The powder has no surface treatment at all. Sonication was applied but particles quickly drop to the bottom. I do not know if it's a possible task due to the relatively large particle size, but it does work for sub-micrometric powder with aid of oleic acid.
nothing else is expected for high density particles of µm size in a low density, low viscosity fluid (Stokes law). Only solution microgravity.
Leonardo Ulian Lopes
Surfactants wet and do not, in general, confer stability on a system. Most organic liquids wet better than water, anyway. The 3 stages in making a successful dispersion from a powder are wetting, separation (the crucial step), and stabilization.
For your system, particle size and density are crucial. A quick Stokes' Law calculation (which you must do) shows that 5 µm Fe (assumed density ~ 7.5 g/cm3) or similar will not stay in suspension for more than a second or so. Your system is way too big by 2 orders of magnitude or so. This is actually the problem you need to solve.
So you need your material <
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