SU814432A1 - Method of production of metal aerosols - Google Patents

Description

(54) METHOD FOR OBTAINING METAL AEROSOLS

where W is the evaporation rate of the metal

in vacuum, g / cm2; Ji is molecular weight; Рц - pressure of saturated steam,

mm Hg v .; T - temperature, K

With an increase in the pressure of the medium, the evaporation rate decreases due to a decrease in the diffusion coefficient and at atmospheric pressure is several orders of magnitude lower than the calculated one. By placing the vaporized metal in an inert gas stream, the rate of evaporation can be significantly increased. If, in this case, the jet velocity does not go beyond the limits of the flow laminarity, then the metal atoms and aerosol particles mainly move in the direction of the strut and are removed from the inductor region without falling onto the walls. This allows the metal aerosol to be continuously collected or introduced into the reaction medium during its formation without contact with the atmosphere.

To obtain aerosols of metals, an installation of the type LGZ-10a, with an output of 8 kW, with a frequency of 400 kHz is used.

An installation diagram for implementing the method is shown in the drawing.

Inductor 1 is made of a copper tube with a diameter of 3 mm and has on top two and-bottom three turns with the opposite direction of current. A glass tube 2 with a diameter of 18 mm was inserted inside the inductor. The upper end of the tube is sealed with a rubber seal and closed with a gauge bushing 3, through which argon and aluminum wire 4 is introduced, with a diameter of 1.5 mm.

After supplying argon and switching on the high-frequency current, aluminum wire was introduced into the inductor, at the end of which aluminum was accumulated, and then the ball 5 of molten aluminum was separated. As its diameter increases, the heating increases and when the temperature reaches about, the oxide film dissolves. This moment is the beginning of evaporation, the intensity of which increases with the size of the droplet and its temperature.

The resulting aerosol b is continuously discharged from the device by the gas flow without contact with the walls of the tube.

As aluminum is consumed, aluminum is added to the drop by a uniform aluminum feed with aluminum wire, which, in contact with the drop, melts in portions.

When the flow rate of argon. 120 l / h in a tube with a diameter of 8 mm

aerosol removal was provided. The evaporation rate at the temperature is 0.5 g / min.

The aerosol is collected by using a fabric filter at the lower end of a tube immersed in a liquid medium, as well as by freezing argon with liquid nitrogen. The latter method provides 100% capture of the aerosol and allows you to work with the regeneration of argon.

The dispersion of the resulting aerosol is determined using an electron microscope of the type EMR.

In a stream of argon and gels, aerosols of aluminum with particles of strictly spherical shape are obtained; however, the dispersion of particles obtained in a current of gels is almost an order of magnitude higher than in argon. The average particle size of the aluminum aerosol is 10 cm and 10 cm. Experiments carried out with other strains show the versatility of the method. Magnesium iron, copper, and nickel are subjected to dispersion. In the case of iron, copper and nickel, aerosol particles of a spherical shape are obtained, in the case of a magnesium a volume polyhedron close to a sphere.

By varying the velocity of the jet of gas or pressure, the dispersion of the particles can be changed. A decrease in pressure, as well as an increase in jet velocity, increases the degree of dispersion, which is associated with a change in the volume in which the aggregation of particles occurs.

The performance of the method can be easily increased by using more powerful high-frequency installations.

Claims (1)

1. Vinogradov M.I. Instruments and experimental technique. 1960, I 4, pp.1-112 ..W