Atomization Of Molten Metal Research Articles

遠心噴霧粉末製造の水モデル解析

Some of the processing parameters for centrifugal atomization of molten metal were studied by means of a model-experiment using water.The shape and revolution velocity of the high speed rotating stages affected the size and the scattering distribution of disintigrated droplets. In the atomization using a flat stage, liquid disintegrated into smaller particles but sticked considerably to the wall of the apparatus. Conical type stages lessened the sticking and increased the portion of the larger drops slightly. Higher velocity revolution made finer particles and narrowed the scattering range of drops at the bottom of the chamber closely to the center. The wettability of the liquid on the stage surface was found to be an important factor for the disintegration of the liquid. Enhanced wettability brought direct drop formation, while poor wettability brought ligament disintegration.

Production of metal powders from melts by centrifugal atomization

A study was made of centrifugal atomization of molten metals in argon at low argon consumption rates [(5.2–7.5) · 10−3 NTP m3/kg]. Output with a single injector attained 30–40 kg/h. Increasing the molten metal head to 0.6–0.8 MPa and decreasing the nozzle diameter to 0.3 mm substantially increased the fineness of the powders. Raising the head still further influenced the effectiveness of atomization to a smaller extent, and decreasing the nozzle diameter to less than 0.3 mm coarsened the powders. Powders of magnesium, aluminum, and Br020 alloy. (20% Sn-Cu bronze) produced by centrifugal atomization of superheated (by about 30–50°K) melts in an inert atmosphere (argon) had spherical particle shapes, which imparted to them good flowability. The oxygen content of the powders was low (less than 0.08%).

Structural and morphological investigations of an atomized iron powder. I. Investigation of particles of a starting powder

The particles of practically all fractions of a pig iron powder generally have internal voids and a conchoidal structure. The voids in the particles form as a result of a carbon oxidation reaction taking place during the atomization of molten metal, which is accompanied by evolution of gaseous products. The degree of oxidation of fine atomized powder particles is greater than that of large ones. The oxide phase in the powder is composed of almost pure iron oxides: FeO, Fe3O4, and, to a smaller extent,α-Fe2O3.

Centrifugal atomization of molten metals with particle cooling in a liquid medium

A new apparatus has been developed for the centrifugal atomization of metals and alloys with particle cooling in a liquid medium. The apparatus, which is much smaller in size than the conventional atomization units, enables alloys of various chemical compositions to be atomized uncontaminated by metal particles from previous heats. Powders produced by this process are characterized by a dense, disperse structure and a low oxygen content. A small-sized unit has been designed and constructed for the centrifugal atomization of air- and vacuum-melted metals and alloys.

Experimental investigation of the process of powder manufacture by centrifugal atomization

A plant has been constructed, and a method developed, for the production of nickel alloy powders by centrifugal atomization of molten metal. A high-quality powder produced by this method was virtually free from gas pores in its <630-μm fraction and contained not more than 0.008 wt. % of oxygen.

A gas-dynamic test stand for the investigation of nozzles used in the atomization of molten metals

1. A gas-dynamic test stand intended for the determination of the blast characteristics of compressed-air atomization nozzles has been designed and constructed. 2. An experimental procedure involving the plotting of suitable diagrams has been developed for the measurement of the parameters of gas streams issuing from nozzles.

Aerodynamic characteristics of nozzles for the atomization of molten metals

Aerodynamic characteristics of nozzles for the atomization of molten metals

Experimental investigation of the nondimensional factor for molten metal atomization

1. An experimental technique has been developed for the determination of the atomization factor in the disintegration of molten metal drops with a gaseous stream. 2. Values of the atomization factor were experimentally determined for the disintegration of tin drops 1±0.2 mm in diameter with an air stream. 3. Experimental values of the atomization factor were found to be in good agreement with calculated data.

Calculation of compressed-air atomizing nozzles

1. A method is proposed for calculating the nozzles of compressed-air units for the atomization of molten metals. 2. Nozzles of atomizing units designed using this method result in the formation of metal — air jets of optimum diameter, which minimize the extent of drop coagulation in the atomization zone.

Energetic parameters of the atomization process

1. A phenomenological description is given of the atomization of molten metals by a gas stream; an examination is made of the energy balance of the process as a whole and of its individual elements. 2. Recommendations are given for increasing the productivity of the atomization process, lowering its cost, and raising its efficiency by varying individual, controllable technological parameters.

The formation of metal powders by ultrasonic atomization of molten metals

Ultrasonic liquid automization was first described in 1927. Since then the subject has caught the imagination of both academics and industrialists. This paper describes the continuation of work started by Stamm on the ultrasonic automization of molten metals. In this work experiments were extended to atomization of metal melts with melting points up to 700°C and to frequencies up to 0.8MHz. The example of ultrasonic atomization is used to show that the mechanism of atomization is in accord with the surface wave theory.

Investigation of the manufacturing technology and properties of sintered filters

1. The method of preparation of spherical metal powders, based on the melting of powders with irregularly-shaped particles mixed with inert fillers, may be recommended together with the method of atomization of molten metals. Unlike the latter, the melting method does not require any melting equipment or special atomizing devices. 2. For raising the strength characteristics of sintered filters from bronze, copper, and nickel powders and lowering their sintering temperature, it is desirable to alloy these powders with phosphorus by adding 1.5–2% of diammonium hydrophosphate to the starting powders. 3. The permeability of sintered filters is determined by the particle size of the powder employed, and the porosity and wall thickness of the filter. The data obtained for the effect of these factors on permeability may be recommended for practical utilization. 4. At equal permeability, sintered filters secure a higher degree of removal of contaminants from the medium being filtered than paper filters.