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The fundamentals of mathematical modeling of the modes of obtaining an ultrafine powder by metal particles laser ablation of vertically falling in an inert gas medium under the action of gravity, provided that these particles flow around the laminar flows of this gas and are outlined. Using the results of the research as an example, the practical p...
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... metal powder particles have a monospherical shape and a smooth surface, and a metered feed device provides them with a consistent exit and a vertical fall without collisions in an inert gas environment. In this case, they fall inside a hollow optically transparent tube (Figure 1) with smooth inner surfaces. The inside tube diameter (D T ) is larger than the particle diameter (D 0 ). ...
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... the same time, the effect of the thickness of powder pressure layer on the surface temperature of vertical falling particles and its distribution in the surface layer at the depth of r =5μm after the effect of a single pulse of laser radiation was taken into account (Figure 10a). The character of variation of particle surface heating temperature from this pulse is shown in Figure 10b. ...
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... the same time, the effect of the thickness of powder pressure layer on the surface temperature of vertical falling particles and its distribution in the surface layer at the depth of r =5μm after the effect of a single pulse of laser radiation was taken into account (Figure 10a). The character of variation of particle surface heating temperature from this pulse is shown in Figure 10b. ...
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... on Figures 6-10 and Table 1, it follows that the value of the relative ablation of the material from the particle surface (Figure 11) will depend on the amount of powder supplied to the laser impact zone (on its consumption). If the energy of the laser radiation pulse is W = 3 J, then at a flow rate G = 0.5 g/min, it will be 45-47% of the entire mass of the particle, and at a flow rate of the studied powder G = 2 g/min it will be only 16-18%. ...
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... on Figures 6-10 and Table 1, it follows that the value of the relative ablation of the material from the particle surface (Figure 11) will depend on the amount of powder supplied to the laser impact zone (on its consumption). If the energy of the laser radiation pulse is W = 3 J, then at a flow rate G = 0.5 g/min, it will be 45-47% of the entire mass of the particle, and at a flow rate of the studied powder G = 2 g/min it will be only 16-18%. ...
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... on those shown in Figures 7-11 results, it is assumed that at normal (р = 100 kPa) pressure of an inert gas (argon), a complete transition to the vapor-gas phase of titanium particles with a diameter of D х =50μm that fell into the laser ablation zone (Figure 5) can occur at a speed powder supply of G = 0.2 g/min., 50%-at G = 0.5 g/min., and 20%-at G = 1.8 g/min. At this flow rate, the granulometric distribution F(D x ) of the condensed particles of the new phase will be as shown in Figure 12.IfatG = 0.2 g/min. ...
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... on those shown in Figures 7-11 results, it is assumed that at normal (р = 100 kPa) pressure of an inert gas (argon), a complete transition to the vapor-gas phase of titanium particles with a diameter of D х =50μm that fell into the laser ablation zone (Figure 5) can occur at a speed powder supply of G = 0.2 g/min., 50%-at G = 0.5 g/min., and 20%-at G = 1.8 g/min. At this flow rate, the granulometric distribution F(D x ) of the condensed particles of the new phase will be as shown in Figure 12.IfatG = 0.2 g/min. Stepwise increases the pressure of the inert gas, then the granulometric distribution will have the form shown in Figure 13, and the relative mass distribution (M) will be as shown in Figure 14. ...
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... this flow rate, the granulometric distribution F(D x ) of the condensed particles of the new phase will be as shown in Figure 12.IfatG = 0.2 g/min. Stepwise increases the pressure of the inert gas, then the granulometric distribution will have the form shown in Figure 13, and the relative mass distribution (M) will be as shown in Figure 14. ...
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... this flow rate, the granulometric distribution F(D x ) of the condensed particles of the new phase will be as shown in Figure 12.IfatG = 0.2 g/min. Stepwise increases the pressure of the inert gas, then the granulometric distribution will have the form shown in Figure 13, and the relative mass distribution (M) will be as shown in Figure 14. ...
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... those presented in Figures 12 and 13 results of the normal-logarithmic granulometric distribution, it follows that in the case of laser ablation under consideration, the condensed particles of the new phase form a powder, the fractional composition of which will be fifty times less ($ 1 μm) than the original one ($D 0 =50μm). If an ideal gas filter from dust with particles smaller than 250 nm is placed at the exit of the laser ablation chamber (Figure 5), then after it the granulometric distribution of condensed particles of the new phase will be as shown in Figures 15, 16. ...
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... those presented in Figures 12 and 13 results of the normal-logarithmic granulometric distribution, it follows that in the case of laser ablation under consideration, the condensed particles of the new phase form a powder, the fractional composition of which will be fifty times less ($ 1 μm) than the original one ($D 0 =50μm). If an ideal gas filter from dust with particles smaller than 250 nm is placed at the exit of the laser ablation chamber (Figure 5), then after it the granulometric distribution of condensed particles of the new phase will be as shown in Figures 15, 16. ...
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... the presented Figures 14-16 of the data it follows that within an hour at G = 1.8 g/min, nine times more particles of the initial titanium powder will pass through the laser ablation zone than at a flow rate of 0.2 g/min. In this case (Figure 17), the number of particles of a new phase formed after laser ablation with a size of less than 250 nm will also be nine times greater. ...
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... the presented Figures 14-16 of the data it follows that within an hour at G = 1.8 g/min, nine times more particles of the initial titanium powder will pass through the laser ablation zone than at a flow rate of 0.2 g/min. In this case (Figure 17), the number of particles of a new phase formed after laser ablation with a size of less than 250 nm will also be nine times greater. ...
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... of the model studies results (Figures 12-17) allows us to draw the following conclusions. 1. ...
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... conducting laboratory studies, a powder laser stereo lithography unit (analogous to a 3D printer) was used as the main technological equipment [13]. The appearance of this analogue of this 3D printer is shown in Figure 18, and its characteristics are shown in Table 3. As the main equipment in the design of a 3D printer analog, the following were used: a pulsed solid-state laser 1, an optical-mechanical system 2 for focusing and positioning on the plane of the laser beam, a sealed technological chamber 3 with a vertically moving construction platform, a powder dispenser and a supply and exhaust system supplying working gas, as well as a control computer 4. To accommodate additional equipment, a modular compartment 5 is provided here. ...
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... to the block modular design, when conducting research in the technological chamber of a 3D printer analogue according to the scheme shown in Figure 19, opposite the lens of the opto-mechanical system focusing on the laser radiation stream 1, a conical laser beam shaper 2 was installed, as well as a powder feeder 3, a dispenser 4, an ultrafine powder sampling device 6, and an FT-3-1109 microfiber filter (Munktell) 7, a hopper for collecting unevaporated powder 8, and a bubbling filter 9. ...
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... results of laboratory studies of the possibility of isolating by filtration of an ultrafine powder of a fraction ≤250 nm obtained from vertically falling spherical particles of titanium of 45-63 μm fraction using laser ablation in the modes recommended by modeling, concerning the relative amount (14-16%) of the separated fraction with respect to the initial one, are also consistent with the forecast indicators (Figure 16) obtained by modeling. Figure 18. ...
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... results of laboratory studies of the possibility of isolating by filtration of an ultrafine powder of a fraction ≤250 nm obtained from vertically falling spherical particles of titanium of 45-63 μm fraction using laser ablation in the modes recommended by modeling, concerning the relative amount (14-16%) of the separated fraction with respect to the initial one, are also consistent with the forecast indicators (Figure 16) obtained by modeling. Figure 18. Appearance of metallurgical 3D printer analogue. ...
