Liquid Metal Jet Research Articles

The shape of liquid metal jets under a non-uniform magnetic field. (1st report Experimental results for jets issuing from circular and rectangular nozzles)

Continuous casting is becoming standard practice in industrial metallurgy. Some subsequent process could perhaps be saved and the quality of solidified ingots improved if the non-contacting shape control method was developed. In this paper we present the results of an experimental investigation of a jet of mercury emanating from circular and rectangular non-conducting nozzles situated at the end of electromagnetic pole pieces where the magnitude of the magnetic field decreases to zero. The shapes of the free surface of the jet are measured by a spot electrode probe under various experimental conditions. In such a non-uniform magnetic field, there is a longitudinal, recircular current flow which induces the cross-sectional force and increases the jet aspect ratio bj/hj. The value of the aspect ratio of the jet issuing from a rectangular nozzle 15 mm wide and 3 mm high increases up to 80.

Hereditary influence of the starting structure of powder particles on the mechanical properties of 30KhN3MF constructional steel

An investigation into the structure and morphology of a 30KhN3MF steel powder produced by atomizing a jet of liquid metal with nitrogen has shown that the rapid cooling experienced by the particles of such a powder ensures a predominantly cellular character of solidification. In the particles of the 30KhN3MF steel powder intercellular microsegregation of alloying and impurity elements is observed. A P/M material produced by HIP is free from internal discontinuities, but individual granules surrounded by oxide films are clearly visible in its macro- and microstructures. The presence of these films, by disturbing the homogeneity of material, has an adverse effect on the mechanical properties of the steel after HIP. P/M 30KhN3MF steel fractures over the surfaces of its powder particles. Plastic working and subsequent heat treatment of 30KhN3MF steel sheets ensures that, at the same level of toughness and strength and ductility characteristics in static tensile testing, the work of crack propagation is greater compared with 30KhN3MF steel produced by the orthodox process. The rupture of 30KhN3MF steel sheet has a dual character, tough, fine-grained fracture predominating between the oxide film layers, along which regions of lamination and cleavage can be detected.

A three dimensional representation of fluid flow induced in ladles or holding vessels by the action of liquid metal jets

A three dimensional flow model is proposed for describing the recirculatory flow patterns generated by coherent jets of metal entering ladles or holding vessels. Based on previous lam-inar and turbulent flow models1,2 developed for axisymmetric conditions, it was decided that a transient three dimensional, laminar flow model was best suited to predict the effect of jet angle, jet location and ladle aspect ratio on resulting flow patterns. It is shown that the ladle’s shape and the jets location and entry angle are critical in establishing the nature of the recirculating flow patterns, and that in some instances, surface flow along the minor axis can reverse.

Electric-pulse disintegration of a jet of liquid metal

Electric-pulse disintegration of a jet of molten metal can be employed for producing both granules and powders. In this process the yield of fine fractions can be increased by: increasing voltage between the electrodes; decreasing to the permissible minimum the distance between the electrodes and the initial jet diameter; using a dc supply; employing a discharge circuit of low inductance and high capacitance; disintegrating a hollow jet.

The production of metal fibres and wires directly from the melt

The basic problem associated with the production of fibres directly from low viscosity melts is summarised, and a simplified attempt at qualtifying the effects of the various physical parameters associated with stable liquid jet formation is presented. Experi- designed to observe the form of liquid jets issuing from a capillary tube over a range of velocities are described. The results of these experiments are correlated with the theoretical treatment. Finally, a brief description is given of recent attempts in which, by various means, an extruded jet of liquid metal has been succesfully stablished to produce a fibre or wire on solidification.

Stability and disruption of plane liquid metal jets

1. The variation of the stability of a liquid metal jet with jet cross-sectional geometry has been determined quantitatively. 2. Fundamental theoretical relationships have been derived describing the stability and disruption of liquid metal jets of various shapes in a gas stream. 3. A dimensionless relationship has been derived enabling the optimum jet disruption conditions, resulting in the least energy losses, to be determined.

Behavior of liquid metal stream in a transverse magnetic field

This is a theoretical study of the effect of a transverse magnetic field on the flow characteristics of a two-dimensional laminar submerged jet stream of an electrically conducting, viscous, incompressible fluid. The analysis may be applicable to liquid metal jet streams for two limiting cases: (i) small magnetic field or (ii) slow motion. In either limiting case, an increase in the intensity of the magnetic field is shown to enhance the extent of velocity decay in the downstream direction.

Tests with Solid Brushes on the Canberra Homopolar Generator

EARLY in 1963 a programme was begun with the view of establishing whether or not solid brushes could be used instead of liquid metal jets to collect the required current (1.6 million amp) from the rotors of the Canberra homopolar generator. Within the first few weeks of investigation it became clear that there were no insuperable problems. Many pilot tests were conducted and details of the design will be published later. Since then, brush gear has been designed, manufactured and installed, and large-scale tests have been made with this gear in the homopolar generator. The behaviour of these brushes has been very satisfactory.