Electricity turned the droplets of molten metal in a continuous thread

American scientists filed an electric current of various voltages on the flow of the melt of indium and gallium, and learned to make him a thread instead of individual drops. The obtained filament was stable up to the size of 64 cm, the thickness of the threadlike flow was equal to 100 micrometers. An article which examined in detail the behavior of metal flow at different speeds and applied stresses, published in the journal Proceedings of the National Academy of Sciences.

If you open up the faucet, then the resulting fine jet after a certain distance they will fall of individual drops — it happens due to surface tension, which tends to reduce the surface area (in our case, in cylindrical shapes, the surface area of more than several spherical particles). This phenomenon in the fluid stream (it is called the instability of Rayleigh — Plateau) have found use in inkjet printers, industrial spraying and fuel systems. However, to get rid of this instability is still not possible — you need to either reduce the surface tension or increase viscosity of the liquid. Even in the case of the flow of fine glass particles, whose surface tension is zero, the scientists observed clustering of drops at the expense of cohesion.

From molten metals almost always fly from the nozzle individual droplets instead of a jet — in these fluids is too little flow velocity, high viscosity and surface tension (more than 500 Newton per meter). But in some cases it is possible to and stream: for example, if you increase the flow rate of one meter per second or to stabilize the jet by surface oxide of the metal (then the drops will not be formed through the microsecond and one second after departure from the nozzle). However, these methods do not allow for a stable metal stream, which is interesting in the process of obtaining wires for flexible electronics.

A group of physicists and chemists under the guidance of Michael Dickie (Michael D. Dickey) found a method for easily producing a steady jet of metal alloy of gallium and indium that is not terminated at a great distance. In the experiment, the scientists squeezed out of the molten metal through a glass tube into the sodium hydroxide solution and applied the voltage between the platinum electrode in the solution and metal.

Due to the tension of the metal on the surface were oxidized, thereby an effective surface tension is significantly reduced. Depending on the voltage and flow rate of tube metal was obtained in different forms: drops, drops United, thread, thread tree, a balloon and a bunch of drops. The transition from dripping to the threadlike condition is not dependent on flow rate, so this process can be considered to be primarily electrochemical.

At a voltage of 0.7 volt drop of contact between the thin bridges, but occasionally jet out of steady state and breaks the bridge with fine droplets. By increasing the voltage to 0.8 volts joints thicken, and the drops are becoming blurred — thus the cylindrical thread of the molten metal. Upon exiting the nozzle the jet is a little blurred, but after a centimeter from the exit of the tube the cross section of the flow becomes stable, its diameter equal to 100 micrometers. At high voltages (one to two volts) of the oxide layer increases and hinders the free flow of metal due to this and get other forms from the tree of the thread to a bunch of droplets.

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