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Denysenko O.I., a Candidate of Technical Sciences
National Metallurgical
ON FORMATION OF
IMPULSE OF HIGH-SPEED DIPHASE FLOW FOR METAL-COMPOSIT SYNTHESIS
Experimental investigation of processes of encounter of
solid oxide microparticles (within the ranges of dimensions 0,01 – 20
micrometers and speeds 100 – 800 m/c) with an obstacle made from the electrode
flong as well as the analysis of physical conditions of connection of
microparticles with the surface depending on their speed and concentration are
of considerable fundamental and practical interest [1], and their results can
be used for optimization of synthesis technique of metal-composit electrode
structures.
The basic principles of the automation system of
experimental assembly for injection formation of metal-composit construction
are set forth in [2]. The principal elements of the assembly for injection
formation of metal-composit are as follows: a supersonic nozzle meant for
acceleration of microparticles to high speeds; heaters of the work substrate
and carrier gas for oxide particles; a powder consumption batcher; an
ultrasonic generator for the substrate material activation; a reaction chamber
with a placed inside control system positioning the substrate with regard to
the nozzle section; valves for make-and-break gas supply to the supersonic
nozzle and batcher.
The system operates in the following way. Having started
up the program, the experimentalist, using a
keyboard, sets a make-and-break time schedule of gas supply valves,
stepper motors of batcher and substrate positioning, the ultrasonic generator,
and desired temperature values of substrate and carrier gas for oxide
particles. After starting up the experiment, the program sends steering
commands to the peripheral devices (for example, to opening of a required gas
supply valve) according to the preset time schedule.
Necessity of economically appropriate and efficient use
of processing resources (electric power, compressed gas, powders of
electrochemically active oxides, etc.) leads to inevitability of formation and
use of oxide particles in experiments on research into their injection upon
formation of metal-composite electrode of diphase flow impulses (see Fig. 1).
Fig. 1. A free-flowing out into atmosphere diphase flow impulse
visually watched upon frame-by-frame scanning (the time magnifier method).
By the same reasons the most attractive seems the use of
diphase flow impulses, that are limit short with regard to the equipment that
forms them, and in the presence of which injection of oxide particles into
metal-composit is observed. The specificity of diphase flow impulses formation
upon short intervals of the gas supply valve opening at the supersonic nozzle input
determines the necessity of placing of the injected matter powder between
nozzle and valve.
Computer control of the valve is fulfilled by setting or
changing of the logic signal level on the electronic switch controller through
which the power winding of the valve is connected to the electric power source.
It was defined experimentally that upon duration of computer valve control
signal less than 3∙10-2 c,
gas valve opening does not happen, probably, as a result of transient
sluggishness. In consequence of the same reasons the dependence of interval Δτ of the gas valve opening at the
supersonic nozzle input on the duration Δt of computer signal of this valve
control, shown graphically on figure 2, has explicit nonlinear character.
Fig.
2. Dependence of interval Δτ of the gas valve
opening at the supersonic nozzle input on the duration Δt of computer valve control signal.
The information about functional character and type (see
Fig. 2) of dependence of the interval of openness of the gas valve (used for
supplying gas carrrying oxide particles and controlled by computer) on duration
of the steering command is useful both for manual control of the high-speed
diphase flow impulse and for construction of the automation system of dynamic
control of the process of metal-composit electrode synthesis.
Literature
1. Denysenko O.I. Mesoscopic Aspect of Structural
Engineering of Metal-composit Cathode // Materials of the First International
Research-and-Practical Conference “News of Scientific Thought – ‘2006”. – V. 5. Technical Sciences. – Dnepropetrovsk: Science and Education, 2006. – P. 3-5.
2. Denysenko O.I., Kalinushkin Å.P. Automatic Control of Firmware Complex for Nanostructure Synthesis // Collected works of the 13th International Scientific and Technical Conference on Automatic Control (Automation-2006). – Vinnytsya, UNIVERSUM-Vinnytsya, 2006. – P. 190.