Viscosity and Specific Electrical Resistance of Gallium Intermetallic Compounds

Introduction. Experimental operation of an asynchronous electric motor with a phase rotor, equipped with a sliding liquid-metal contact unit, showed that with certain design parameters of the components of the latter, after stopping the electric motor, drops of gallium or its intermetallics splashed over the inner surface do not flow down to the bottom on their own, but settle on the inner surface of the contact unit. One of the reasons for this is the high values of viscosity indices. Considering the possibility of using gallium intermetallics of various compositions as a working fluid, it is of scientific interest to evaluate the viscosity of gallium intermetallics. For practical use, it is advisable that gallium intermetallics have a minimum specific electrical resistance. The purpose of the study is to evaluate the viscosity of gallium intermetallic compounds with minimal specific electrical resistance, of various compositions, which can be used as the working fluid of asynchronous electric motors with a phase rotor equipped with a sliding liquid metal contact unit. Calculation. The peculiarity of the assessment is that the “apparent” viscosity of gallium intermetallic compounds is determined. This is due to the fact that the main part of the intermetallic compound by weight is pure gallium, the remaining components (indium, tin and zinc), being in solid form and mixing with gallium, pass into the liquid phase. As a first approximation, we assume that, being part of the intermetallic compound, indium, tin and zinc have a viscosity close to the viscosity of the liquid metal at the melting point, i.e. the maximum possible for the liquid state. The real viscosity of the intermetallic compound can only be determined in a direct experiment. Processing of the Results Obtained. It is advisable to use intermetallics at elevated temperatures up to temperatures that the insulation of the electric machine can withstand. From the point of view of minimizing the toxicity of sliding liquid contact units in relation to the operator and the operating environment of the electric machine, it is advisable to use gallium intermetallics that do not include indium. Conclusions. Conclusions. As a result of calculations at permissible temperature conditions of electric motor operation (temperature 200 °C), it was established that the minimum viscosity will be possessed by gallium intermetallic containing 76% Ga and 24% In, but more preferable in terms of a set of parameters is the use of intermetallic containing 95% Ga and 5% Zn.