RU2765190C1 - Device and method for producing superfine low-melting spherical metal powder using drop spraying - Google Patents

Abstract

FIELD: 3D printing.

SUBSTANCE: invention can be used in 3D printing and the production of semiconductor integrated circuits. A device for producing ultrafine low-melting spherical metal powder using drop spraying contains a housing (13), a crucible (7) and an area for collecting powder, equipped with a collecting plate (12) and a rotating disk (9) connected to an electric motor (10), in which the element for spraying is made of a metal material that provides a contact angle with drops (15) less than 90 °, and is inserted into the main part. Metallic raw materials are loaded into the crucible (7) and hermetically closed. Then, by means of mechanical (17) and diffusion (18) pumps, a vacuum of 0.1 MPa is created, resistive heating is carried out by a heater (4), by means of an electric motor (10), the disk (9) is rotated at a preset speed of 10000-50000 rpm and s the induction heating coil (14) is used to heat its upper surface to a temperature exceeding the melting point of the metal raw material. The holding time after complete melting is 15-20 minutes, the induction heating voltage is 0-50 V, and the time is 5-15 minutes. A high purity inert shielding gas is fed through the first and second inlet pipes (2) and (21) to create back pressure in the crucible (7). A pulse signal is applied to the piezoelectric ceramics (1), and by means of the transfer rod (3) and the pressure plate (5), the molten metal located in the region near the central hole is moved so that it is ejected from the lower part of the central hole with the formation of identical drops (15) which freely fall onto the rotating disc (9). The resulting metal powder (11) is collected on a collecting plate (12).

EFFECT: obtained low-melting ultrafine metal spherical powder is characterized by high sphericity, good fluidity and spreadability.

10 cl, 5 dwg

Description

FIELD OF TECHNOLOGY

The present invention relates to the field of technology for producing ultrafine spherical microparticles, and in particular it relates to a device and method for producing ultrafine low-melting spherical metal powder using drop spraying.

BACKGROUND OF THE INVENTION

Due to the radical change in technology, spherical metal powder has a great demand for rapid prototyping using 3D printing, semiconductor integrated circuits, etc., and its quality requirements are also continuously increasing. The metal powder used in 3D printing requires high sphericity, uniform particle size, no secondary droplets, as well as good spreadability and uniform flow.

Today, in China and abroad, atomization, including air atomization, water atomization, centrifugal atomization, and the like, is used in production methods for metal spherical powders. However, the powders obtained using the above spraying methods have a relatively wide fineness, and multiple sieving is necessary to obtain particles whose size satisfies the requirements for use; in addition, the sphericity is poor and there is a large amount of secondary droplets on the powder, so the usage requirements cannot be met, and the production efficiency is low.

Most of the powders used in China are imported and cannot meet the requirements for use at all. Therefore, it is important to search for devices and methods for obtaining ultrafine spherical metal powders, which are characterized by high quality.

SUMMARY OF THE INVENTION

From the above, such technical problems characteristic of existing processes for producing metal powder as poor fluidity and spreadability, low yield of a suitable product, low efficiency, etc. become apparent, therefore, a device and a method for producing ultrafine low-melting spherical metal powder using drop spraying are proposed. The present invention generally combines very small orifice pulse injection and centrifugal atomization, and proposes a rotating disk design, and induction heating of the surface of the rotating disk is carried out, and thus, according to the present invention, with regard to liquid metal, the traditional form of molten metal separation is eliminated, and separation in the form of streams, which can only be carried out if the spray medium is an aqueous solution or an organic solution; Compared with existing centrifugal atomization technologies, streak atomized powder can be a major step forward in terms of obtaining ultra-fine sizes; at the same time, low-melting ultra-fine metal spherical powder can be obtained in this way, which is characterized by high sphericity, good fluidity and spreadability, no secondary droplets, and meets the requirements of the application.

The following are the technical means used in the present invention.

A device for producing ultrafine low-melting spherical metal powder using drop spraying, comprising: a body, a crucible installed in said body, and an area for collecting powder, while said area for collecting powder is located in the lower part of said body, and said crucible is located above said powder collection area;

the specified crucible is an annular structure with internal and external elements, the Central line of which is the axis; the lower part of the inner containing cavity of the specified crucible and the lower part of the outer containing cavity of the specified crucible are provided with through central holes; between said lower part of the inner containing cavity and said lower part of the outer containing cavity, a space is provided for the passage of molten metal; in the inner containing cavity of the specified crucible is a transmission rod connected to the piezoelectric ceramics located outside the specified body; the specified transmission rod at the lower end is provided with a pressure plate; the specified pressure plate is located directly above the Central hole of the specified internal containing cavity;

said body is provided with crucible inlet pipes extending into said crucible; said body is further provided with a mechanical pump and a diffusion pump in communication with said crucible; said body is further provided with a cavity inlet pipe and a cavity air outlet valve;

said powder collection area comprises a collecting plate installed at the bottom of said body and a rotating disk located above said collecting plate, connected to an electric motor and designed to atomize metal powder particles;

the specified rotating disk contains the main part, the element for spraying with a flat surface and a vent;

said main body is a T-shaped longitudinal section main member, consisting of a receiving part in the upper part and a support part in the lower part; the specified receiving part on the upper surface is provided with a circular recess of a certain radius, coaxial with it in relation to the centers of the circle; wherein said body is made of a material whose thermal conductivity is less than 20 W/(m⋅K);

said flat surface spray element is a round disk element; the specified element in the form of a circular disc corresponds to the specified circular recess and is located in the specified circular recess with an interference fit; the specified element for spraying with a flat surface is made of a material that provides a contact angle with the sprayed drops of less than 90°;

the specified vent is made passing through the specified receiving part and the specified reference part; said vent opening with its upper side in contact with a lower end surface of said flat surface spray member; the specified vent hole bottom side is made in communication with the external environment;

an induction heating coil is additionally provided around said rotating disc.

The above crucible is designed as two chambers located inside and outside, that is, the metal material is placed in the outer chamber; during the melting process, it moves in the form of a liquid material and flows into the region of the central hole of the crucible, where it is displaced downwards by means of a pressure plate located above the central hole and a transfer rod located above the pressure plate, with ejection of drops from the central hole in the lower part of the crucible. Of course, the shape of the crucible is also not limited to the embodiment described above, it is only required that the crucible has a hermetically sealed chamber, and so any design is suitable in which, after filling with protective gas, back pressure can be created to promote the movement of the flow of liquid material to the region near the central holes. The volume of said body must be sufficient so that the drops after centrifugal separation fly off and fall within the collecting plate located below, so that they do not solidify on the inner wall of the body; and the collecting plate area must be large enough to collect the powder.

Preferably, the height of the main body is 10-20 mm; the height of the support part must not be too high and must be less than the height of the receiving part. The upper end surface of said flat surface spraying element protrudes from the upper end surface of said receiving part, while it protrudes within 0.1-0.5 mm. It is only necessary that the height of the protrusion helps to ensure that the scattered metal drops do not touch the main part, but immediately fly into the chamber and fall onto the collecting plate. The diameter of said receiving part is in the range of 10-100 mm, and the diameter of said circular recess is in the range of 5-90 mm.

Said main body is made of zirconia ceramic, silica glass or stainless steel, but it is not limited to the above materials, and it is only necessary that it be a material whose thermal conductivity is less than 20 W/(m⋅K). The size of the top side of said vent hole is less than or equal to the size of the bottom end face of said flat surface spray member; the vent hole is designed so that when a vacuum is created, a more complete suction of the gas in the gaps in the rotating disk can be ensured; it is safer when the rotating disk rotates at high speed, so the larger the contact area of the top side of the vent hole with the bottom end surface of the flat surface atomization element, the better the stability of the flat surface atomization element when generating a vacuum.

In addition, in the specified crucible is a thermocouple; a resistive heater is additionally located outside said crucible. Preferably, the contact angle between the material of the crucible and the molten metal placed in it is more than 90°.

In addition, the diameter of the central hole of the specified crucible is in the range from 0.02 mm to 2.0 mm.

In addition, the rotation speed of said rotary disk is from 10,000 rpm to 50,000 rpm.

In addition, the heating thickness of said induction heating coil is in the range of 5-20 mm; it is connected to a frequency converter and a voltage stabilized power supply located outside said housing, wherein said voltage regulated power supply has a voltage regulation range of 0-50 V.

Moreover, in said device, in the downward direction, said piezoelectric ceramic, said transfer rod, said crucible, said resistive heater, said pressure plate, said rotating disk, and said induction heating coil are arranged on the same axis.

The present invention also provides a method for producing ultrafine low-melting spherical metal powder using drip spraying through the above device, characterized in that it includes the following steps:

загрузку сырья: подлежащий плавлению металлический материал помещают во внешнюю вмещающую полость тигля, расположенного внутри корпуса в верхней части, и герметично закрывают;

loading of raw materials: the metal material to be melted is placed in the outer containing cavity of the crucible located inside the body in the upper part, and hermetically closed;

создание вакуума: посредством механического насоса и диффузионного насоса в указанном тигле и указанном корпусе создают вакуум и заполняют их инертным защитным газом высокой чистоты (обычно гелием или аргоном) так, чтобы в корпусе давление достигало предварительно установленного значения;

creating a vacuum: by means of a mechanical pump and a diffusion pump, a vacuum is created in the specified crucible and the specified housing and filled with an inert protective gas of high purity (usually helium or argon) so that the pressure in the housing reaches a predetermined value;

резистивный нагрев: на основании температуры плавления подлежащего нагреванию сырья устанавливают параметры нагревания резистивным нагревателем и посредством термопары, установленной в указанном тигле, осуществляют контроль в реальном времени за температурой внутри указанного тигля с поддержанием необходимой температуры после полного расплавления металлического материала;

resistive heating: based on the melting temperature of the raw material to be heated, heating parameters are set by the resistive heater, and by means of a thermocouple installed in the specified crucible, the temperature inside the specified crucible is monitored in real time, maintaining the required temperature after the complete melting of the metal material;

индукционный нагрев: посредством электродвигателя обеспечивают скоростное вращение указанного вращающегося диска с предварительно установленной скоростью вращения; затем посредством катушки индукционного нагрева верхнюю поверхность вращающегося с высокой скоростью диска нагревают до температуры, которая выше температуры плавления металлического материала;

induction heating: by means of an electric motor, said rotating disk is provided with a high-speed rotation at a predetermined rotation speed; then, by means of an induction heating coil, the upper surface of the high-speed rotating disk is heated to a temperature which is higher than the melting point of the metal material;

получение частиц: посредством первой впускной трубы тигля и второй впускной трубы тигля, установленных на указанном корпусе и проходящих в указанный тигель, подают инертный защитный газ высокой чистоты для создания в указанном тигле обратного давления, что приводит к заполнению расплавленным металлом центрального отверстия в нижней части указанного тигля; на пьезоэлектрическую керамику подают импульсный сигнал определенной формы волны, при этом указанная пьезоэлектрическая керамика обеспечивает смещение в направлении вниз, и посредством передаточного стержня, соединенного с указанной пьезоэлектрической керамикой, и прижимной пластины, расположенной внизу указанного передаточного стержня, расплавленный металл, находящийся в области около центрального отверстия, перемещают так, что расплавленный металл выбрасывается из нижней части центрального отверстия с формированием одинаковых капель;

obtaining particles: through the first inlet pipe of the crucible and the second inlet pipe of the crucible, installed on the specified body and passing into the specified crucible, an inert protective gas of high purity is supplied to create a back pressure in the specified crucible, which leads to the filling of the central hole in the lower part of the specified crucible with molten metal crucible; a pulse signal of a certain waveform is applied to the piezoelectric ceramics, while said piezoelectric ceramics provides a downward displacement, and by means of a transmission rod connected to said piezoelectric ceramics and a pressure plate located at the bottom of said transmission rod, the molten metal located in the region near the central holes, move so that the molten metal is ejected from the bottom of the Central holes with the formation of identical drops;

identical droplets freely fall on a disk rotating at high speed, while identical melt drops first fall into the center of the rotating disk; since at this moment the centrifugal force is relatively small, the drops will not immediately dissipate outward, but will spread along the rotating disk in a circle, when they spread to a certain limit, where the centrifugal force is large enough, the spreading metal under the influence of centrifugal force on the rotating disk will be in the form the jet moves to the edge of the rotating disk and, finally, separates into small drops and flies off; small drops in the process of falling, being outside the container, harden and form a metal powder, which falls on the collecting plate; at the same time, the pressure plate and the transfer rod are returned to their original position and molten liquid metal passes from the melting vessel in the specified crucible to the region of the central hole;

сбор частиц: однородный сферический металлический порошок собирают посредством собирательной пластины, установленной в нижней части указанного корпуса.

collection of particles: a uniform spherical metal powder is collected by means of a collection plate installed at the bottom of said body.

In addition, the amount of said metallic material loaded into said outer containing cavity is from 50% to 70% of the volume of said outer containing cavity.

In addition, the pressure in the specified housing after creating a vacuum reaches 0.1 MPa; holding time after complete melting of the metal material is 15-20 minutes.

In addition, the voltage range for induction heating by said induction heating coil is 0-50V, and the induction heating time is 5-15 minutes.

Compared with analogues known from the prior art, the present invention has the following advantages:

According to the present invention, a device and a method for producing ultrafine low-melting spherical metal powder using drop spraying are proposed, which combine pulse injection through a very small hole and centrifugal spray, while the metal material melted in the crucible is ejected under pressure and pulse disturbance through a central hole in the lower parts of the crucible with the formation of identical drops; identical drops fall on a disk rotating at high speed and spread over a round disk; the spread metal under the action of centrifugal force will disperse in the form of streams along the rotating disk to the edge of the rotating disk and, finally, will be divided into small drops and fly off, while small drops in the process of falling, ending up outside the container, will solidify. Metal particles obtained by conventional pulse injection through a very small hole have a high sphericity and a uniform temperature change with time, but the resulting powder does not become ultrafine; when combined with centrifugal atomization, the molten metal is separated into jets, which greatly improves the size reduction ratio of the metal powder (particle size less than 50 µm), so that particle size control can be achieved and the requirements of molding technology can be satisfied.

In addition, the rotary disk disclosed in the present invention is an insert structure that adopts a material with poor thermal conductivity, that is, a thermal conductivity of less than 20 W/(m⋅K) for the main body, which can effectively reduce the amount of heat transmitted by the rotary disk. on the high-speed motor, and prevent it from adversely affecting the normal operation of the high-speed motor; whereby, as the flat surface atomization element, a melt atomization material having good wettability, i.e., a material with a contact angle of less than 90°, is used, which promotes droplet spreading on the flat surface atomization element, thereby enabling sufficient atomization of the liquid metal; the flat surface spraying member is connected to the inner wall of the main body by an interference fit so that during high-speed rotation of the rotating disk, the flat surface spraying member does not fly out, thus ensuring its safety; when the flat surface atomization element is installed on the rotating disk, there will be an air hole between the flat surface atomization element and the main body, and when a high vacuum is created in the cavity, a very large pressure difference, which adversely affects the stability of the flat surface atomization member, so a vent hole is provided between the receiving portion and the bearing portion of the rotary disc main portion to communicate between the lower end surface area of the flat surface atomization member and the outside, so that the pressure on both sides of the flat surface atomizing element is kept constant, and further ensures the stability and preservation of the rotating disc during high-speed centrifugal atomization.

The controllability of the process according to the present invention is high, which is manifested in the following: by means of a resistance heater, the temperature of the crucible can be accurately controlled; by means of an inert gas introduced into the crucible and the body, it is possible to regulate the pressure drop in the crucible and the body, while ensuring continuous movement of the molten metal in the crucible chambers in the direction of the central opening of the crucible; through the size of the central hole in the bottom of the crucible, you can adjust the size of the drops; by means of an induction heating coil, the surface temperature of the rotating disk can be adjusted; the ability to control the speed of rotation of the rotating disk allows you to adjust the result of the separation of the molten metal into streams, so you can further control the size distribution of metal microparticles; due to the possibility of regulation and control of technological parameters, it is possible to obtain ultra-fine spherical metal powder.

According to the present invention, an ultrafine metal powder can be obtained to meet application requirements, while the particle size can be controlled, the distribution interval is narrow, the sphericity is high, the temperature change over time is uniform, the structure is simple, the production cost is low, and the production volume is high, therefore it is suitable for industrial production purposes.

DESCRIPTION OF THE SUPPLIED GRAPHICS

In order to more clearly describe the technical solutions according to the embodiments of the present invention or analogues known from the prior art, the accompanying drawings are presented below in a simple form, which should be applied to the embodiments or analogues known from the prior art, while it is clear that the described the accompanying graphics below refer to several embodiments of the present invention, and those skilled in the art can also obtain other accompanying graphics based on these attached graphics without any creative effort.

In FIG. 1 is a schematic representation of the construction according to the present invention.

In FIG. 2 is a schematic representation of the construction of a rotating disk according to the present invention.

In FIG. 3 shows comparative images of a powder obtained using the device and method according to the present invention and a powder obtained using an unimproved device, while (a) shows a powder obtained according to the present invention, and (b) shows a powder obtained using an analogue, known from the prior art.

In FIG. 4 shows comparative images relating to the test surface of a spinning disc according to the present invention and the test surface of a known spinning disc, with (a) showing the surface of a spinning disc with filament separation, and (b) showing the surface of a spinning disc of an analogue known from the level of technology.

In FIG. 5 depicts fluid flow lines on the surface of a rotating disc according to the present invention, with (a) showing fluid flow lines in the region of the middle portion of the rotating disc, and (b) showing fluid flow lines in the edge region of the rotating disc.

On the figures: 1 - piezoelectric ceramics; 2 - the first inlet pipe of the crucible; 3 - transfer rod; 4 - resistive heater; 5 - pressure plate; 6 - right melting tank; 7 - crucible; 8 - cavity; 9 - rotating disk; 10 - electric motor; 11 - metal powder; 12 - collecting plate; 13 - body; 14 - induction heating coil; 15 - drop; 16 - inlet pipe of the cavity; 17 - mechanical pump; 18 - diffusion pump; 19 - air outlet valve of the cavity; 20 - left melting tank; 21 - the second inlet pipe of the crucible; 22 - receiving part; 23 - support part; 24 - element for spraying with a flat surface; 25 - ventilation hole.

SPECIFIC IMPLEMENTATION OPTIONS

It should be noted that the embodiments of the present invention and the features in the embodiments may be combined with each other unless there is conflict. Below, the present invention is described in detail using embodiments with reference to the accompanying drawings.

In order to make the objectives, technical solutions and advantages of the embodiments of the present invention more clear, the following technical solutions of the embodiments of the present invention are clearly and thoroughly described with reference to the accompanying drawings taken in conjunction with the embodiments of the present invention; of course, the described embodiments are only some of the embodiments of the present invention and not all embodiments. What is described below with respect to at least one exemplary embodiment is really only intended to explain and in no way serves to limit the present invention and its application or use. All other embodiments based on embodiments of the present invention and obtained by those skilled in the art without any creative effort fall within the protection scope of the present invention.

It should be noted that the terms used in this document are used solely to describe a particular mode of implementation and are not intended to limit the exemplary modes of implementation of the present invention. For example, except where the context also makes it clear otherwise, it is intended that the singular as used herein also includes the plural; in addition, it should also be understood that the use of the words "include" and/or "comprise" in this description indicates the presence of features, steps, operations, parts, components and/or combinations thereof.

Unless specifically stated otherwise, the relative positions, numerical expressions, and numerical values relating to the elements and steps indicated in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that for convenience of description, the dimensions of each element shown in the attached graphics are not taken in real proportional ratios. Technologies, methods and devices known to those skilled in the art may not be discussed in detail, but in appropriate cases, these technologies, methods and devices should be considered part of the present description. In all of the examples presented and discussed in this document, any specific values should be interpreted as being presented by way of example only and not intended to be limiting. Therefore, other values may be included in the exemplary embodiments in other examples. It should be noted the following: in the attached graphic materials, which will be referred to below, similar numbers and letters indicate similar objects, therefore, if an object is explained in relation to one figure, then it is not required to consider it additionally in relation to subsequent figures.

It should be understood that in the description of the present invention, the relative positions or positional relationships indicated by the words associated with the direction, such as "front", "back", "top", "bottom", "left", "right", "transverse" , "vertical", "perpendicular", "horizontal", "top", "bottom", etc., usually represent relative positions or positional ratios indicated based on the accompanying drawings, and are used for the convenience of describing the present invention, and also to simplify the description; unless otherwise indicated, these relative position-indicating words do not at all indicate or imply that the respective devices or elements must have a specific relative position or be made and used in a specific relative position, so they cannot be construed as limiting the protection scope of the present invention: indicating the relative position of the words "inside" and "outside" indicates being inside and outside relative to the contours of the parts themselves.

For ease of description, this document may use words and phrases that express spatial relationships, such as "above", "below", "on the surface", "located on top", etc., which are intended to describe the location in space, for example, one detail or feature relative to another detail or feature shown in the figures. It should be understood that words and phrases expressing spatial relationships, in addition to the relative positions described in relation to the arrangement of parts in the figures, are also intended to indicate other relative positions during application or operation. For example, if parts shown in the accompanying graphics are reversed, then parts described as being "above other parts or features" or "above other parts or features" will then be positioned as being "below other details or features" or " below other details or elements. Therefore, the exemplary word "above" may include the relative position of "above" and "below". Parts may also be positioned differently (rotated 90 degrees or have a different relative position), and the description of the relative position used in this document is explained accordingly.

In addition, it should be noted that the use of the words "first", "second", etc. to define components is only for the convenience of distinguishing between the respective components, and unless otherwise indicated, the above words do not have a special meaning, so they cannot be be understood as limiting the scope of protection of the present invention.

As shown in FIG. 1, according to the present invention, there is provided a device for producing ultrafine low-melting spherical metal powder using drip spraying, comprising: a body 13, a crucible 7 installed in said body 13, and a powder collection area, while said powder collection area is located at the bottom of said housing 13, and said crucible 7 located above said powder collection area;

the specified crucible 7 is an annular structure with internal and external elements, the Central line of which is the axis; the figure shows that the crucible 7 can be divided into left and right chambers, that is, into the left melting tank 20 and the right melting tank 6; in fact, both melting containers are in the same annular chamber (inside the outer containment cavity); in the process of actual use, a metal material can be introduced into the melting vessel on one side, depending on the amount of powder to be obtained, which can be filled partially or completely; the lower part of the inner containing cavity of the specified crucible 7 and the lower part of the outer containing cavity of the specified crucible 7 are provided with through central holes; between said lower part of the inner containing cavity and said lower part of the outer containing cavity, a space is provided for the passage of molten metal; in the inner containing cavity of the specified crucible 7 is the transmission rod 3, connected to the piezoelectric ceramics 1, located outside the specified housing 13; the specified transmission rod 3 at the lower end is provided with a pressure plate 5; the specified pressure plate 5 is located directly above the Central hole of the specified internal enclosing cavity; said body 13 is additionally provided with crucible inlet pipes extending into said crucible 7 in the region of the left melting container 20 and the right melting container 6 in the corresponding figure, which are respectively the second crucible inlet pipe 21 corresponding to the left melting container 20 and the first inlet pipe 2 crucible, corresponding to the right container 6 melting; said body 13 is further provided with a mechanical pump 17 and a diffusion pump 18 communicating with said crucible 7; said body 13 is further provided with a cavity inlet pipe 16 and a cavity air outlet valve 19;

said powder collection area comprises a collecting plate 12 installed in the lower part of said body and a rotating disk 9 located above said collecting plate 12 connected to an electric motor 10 and designed to atomize metal powder particles.

As shown in FIG. 2, said rotating disc 9 comprises a main body, a flat surface spraying member 24, and an air vent 25;

said main body is a T-shaped longitudinal main body, consisting of a receiving part 22 at the top and a support part 23 at the bottom; the specified receiving part 22 on the upper surface is provided with a circular recess of a certain radius, coaxial with it in relation to the centers of the circle; wherein said body is made of a material whose thermal conductivity is less than 20 W/(m⋅K);

said flat surface spray member 24 is a circular disk member; the specified element in the form of a circular disc corresponds to the specified circular recess and is located in the specified circular recess with an interference fit; the specified element 24 for spraying with a flat surface is made of a material that provides a contact angle with spray drops 15 less than 90°;

the specified vent 25 is made passing through the specified receiving part 22 and the specified support part 23; said vent hole 25 with its upper side in contact with a lower end surface of said flat surface spray member 24; said vent hole 25 has its bottom side in communication with the external environment.

An induction heating coil 14 is additionally provided around said rotating disk 9. With said induction heating coil 14, the heating thickness is in the range of 5-20 mm; it is connected to a frequency converter and a voltage-stabilized power supply located outside said housing 13, wherein said voltage-stabilized power supply has a voltage regulation range of 0-50V. then, by means of the induction heating coil 14, the upper surface of the high-speed rotating disc 9 is heated to a temperature which is higher than the melting point of the metal material;

for said crucible 7, the diameter of the central hole is in the range from 0.02 mm to 2.0 mm.

The rotation speed of said rotating disk is from 10,000 rpm to 50,000 rpm.

In said device, from top to bottom, said piezoelectric ceramic 1, said transfer rod 3, said crucible 7, said resistive heater 4, said pressure plate 5, said rotating disc 9, and said induction heating coil 14 are arranged on the same axis.

During operation, a vacuum is created in said crucible 7 and said housing 13 by means of a mechanical pump 17 and a diffusion pump 18; under conditions of back pressure created by the inlet of an inert gas, the material necessary for manufacturing is heated by means of a resistive heater 4 in the crucible 7; a pulse signal of a certain waveform is applied to the piezoelectric ceramic 1; piezoelectric ceramic 1 provides a downward displacement, which is transmitted by means of a transfer rod 3 and a pressure plate 5 to the molten metal located in the region near the central hole of the crucible 7, as a result of which the molten metal is ejected from the central hole in the lower part of the crucible with the formation of identical drops 15 ; identical drops 15 fall freely on a rotating disk 9 rotating at high speed; identical drops 15 of the melt first fall into the center of the rotating disk 9; since at this moment the centrifugal force is relatively small, the drops 15 will not immediately dissipate outward, but will spread around the rotating disk 9 in a circle; when they spread to a certain limit, where the centrifugal force is large enough, the spread metal under the action of centrifugal force on the rotating disk 9 will move in the form of streams to the edge of the rotating disk 9 and, finally, separate into small drops and fly off; small drops in the process of falling, ending up outside the container, harden and form metal powder 11, which falls on the collecting plate 12.

According to the present invention, there is also provided a method for producing ultrafine low melting spherical metal powder using drip spraying by means of the above device, including the following steps:

загрузку сырья: подлежащий плавлению металлический материал помещают в тигель 7, расположенный внутри корпуса 13 в верхней части, и герметично закрывают; при этом загружаемое количество указанного металлического материала, загружаемого в указанную внешнюю вмещающую полость, составляет от 50% до 70% объема указанной внешней вмещающей полости;

raw material loading: the metal material to be melted is placed in the crucible 7 located inside the housing 13 in the upper part, and hermetically sealed; wherein the loading amount of said metallic material loaded into said outer containing cavity is from 50% to 70% of the volume of said outer containing cavity;

создание вакуума: посредством механического насоса 17 и диффузионного насоса 18 в указанном тигле 7 и указанном корпусе 13 создают вакуум и заполняют их инертным защитным газом высокой чистоты с получением внутри корпуса 13 давления предварительно установленного значения; давление после создания вакуума внутри указанного корпуса 13 достигает 0,1 МПа; время выдержки после полного расплавления металлического материала составляет 15-20 минут;

creating a vacuum: by means of a mechanical pump 17 and a diffusion pump 18, a vacuum is created in the specified crucible 7 and the specified housing 13 and filled with an inert protective gas of high purity to obtain a pre-set pressure inside the housing 13; the pressure after creating a vacuum inside the specified housing 13 reaches 0.1 MPa; holding time after complete melting of the metallic material is 15-20 minutes;

резистивный нагрев: на основании температуры плавления подлежащего нагреванию сырья устанавливают параметры нагревания резистивным нагревателем 4 и посредством термопары, установленной в указанном тигле 7, осуществляют контроль в реальном времени за температурой внутри указанного тигля 7 с поддержанием необходимой температуры после полного расплавления металлического материала;

resistive heating: based on the melting temperature of the raw material to be heated, heating parameters are set by the resistive heater 4, and by means of a thermocouple installed in the specified crucible 7, the temperature inside the specified crucible 7 is monitored in real time, maintaining the required temperature after the complete melting of the metal material;

индукционный нагрев: посредством электродвигателя 10 обеспечивают скоростное вращение указанного вращающегося диска 9 с предварительно установленной скоростью вращения; затем посредством катушки 14 индукционного нагрева верхнюю поверхность вращающегося с высокой скоростью диска 9 нагревают до температуры, которая выше температуры плавления металлического материала; диапазон напряжения для индукционного нагрева посредством указанной катушки 14 индукционного нагрева составляет 0-50 В, а время индукционного нагрева составляет 5-15 мин;

induction heating: by means of an electric motor 10, said rotating disc 9 is rotated at a predetermined speed; then, by means of the induction heating coil 14, the upper surface of the high-speed rotating disc 9 is heated to a temperature which is higher than the melting point of the metal material; the voltage range for induction heating by said induction heating coil 14 is 0-50 V, and the induction heating time is 5-15 minutes;

получение частиц: посредством первой впускной трубы 2 тигля и второй впускной трубы 21 тигля, установленных на указанном корпусе 13 и проходящих в указанный тигель 7, подают инертный защитный газ высокой чистоты для создания в указанном тигле 7 обратного давления, что приводит к заполнению расплавленным металлом центрального отверстия в нижней части указанного тигля 7; на пьезоэлектрическую керамику 1 подают импульсный сигнал определенной формы волны, при этом указанная пьезоэлектрическая керамика 1 обеспечивает смещение в направлении вниз, и посредством передаточного стержня 3, соединенного с указанной пьезоэлектрической керамикой 1, и прижимной пластины 5, расположенной внизу указанного передаточного стержня 3, расплавленный металл, находящийся в области около центрального отверстия, перемещают так, что расплавленный металл выбрасывается из нижней части центрального отверстия с формированием одинаковых капель 15;

obtaining particles: through the first inlet pipe 2 of the crucible and the second inlet pipe 21 of the crucible, installed on the specified body 13 and passing into the specified crucible 7, an inert protective gas of high purity is supplied to create a back pressure in the specified crucible 7, which leads to the filling of the molten metal of the central holes in the lower part of the specified crucible 7; the piezoelectric ceramic 1 is supplied with a pulse signal of a certain waveform, while said piezoelectric ceramic 1 provides a displacement in the downward direction, and by means of a transmission rod 3 connected to said piezoelectric ceramic 1 and a pressure plate 5 located at the bottom of said transmission rod 3, the molten metal , located in the region near the central hole, is moved so that the molten metal is ejected from the lower part of the central hole with the formation of identical drops 15;

identical droplets 15 fall freely onto the high-speed rotating disk 9, while identical melt drops 15 first fall into the center of the rotating disk 9; since at this moment the centrifugal force is relatively small, the drops 15 will not immediately dissipate outward, but will spread along the rotating disk 9 in a circle, when they spread to a certain limit, where the centrifugal force is large enough, the spreading metal under the action of centrifugal force on the rotating disk 9 will move in the form of streams to the edge of the rotating disk 9 and, finally, will be divided into small drops and fly off; small drops in the process of falling, being outside the container, harden and form a metal powder 11, which falls on the collecting plate 12; at the same time, the pressure plate 5 and the transfer rod 3 are returned to their original position, and molten liquid metal passes from the melting vessel in said crucible 7 to the region of the central hole;

сбор частиц: посредством собирательной пластины 12, установленной в нижней части указанного корпуса, однородный сферический металлический порошок собирают.

collection of particles: by means of a collecting plate 12 installed at the bottom of said body, a uniform spherical metal powder is collected.

Embodiment 1

A specific implementation method using the device shown in FIG. 1, to obtain Sn63Pb37 alloy spherical powder:

The Sn63Pb37 welding wire is cut into short lengths of approximately 5 mm and, after ultrasonic cleaning, placed in the melting vessel of the crucible 7; based on the requirements, choose the value of the diameter of the central hole of the crucible, while the diameter of the central hole is in the range from 0.02 mm to 2.0 mm; for example, to obtain particles with a size of 25 μm to 50 μm, a central hole with a diameter of 0.02 mm to 1.0 mm is selected; for example, to obtain particles with a size of 50 μm to 100 μm, a central hole with a diameter of 1.0 mm to 2.0 mm is selected; the loading amount of raw material Sn63Pb37 reaches a value of 50% to 70% of the volume of the melting vessel;

by means of a mechanical pump 17 and a diffusion pump 18, a vacuum level of up to 0.001 Pa is created in the specified crucible 7 and the specified housing 13; inert gas argon is introduced through the first inlet pipe 2 of the crucible and the second inlet pipe 20 of the crucible, as well as through the inlet pipe 16 of the cavity, so that the pressure in the housing 13 and the crucible 7 reaches 0.1 MPa;

a resistive heater 4 is installed on the crucible 7, while a thermocouple is inserted into the lower part of the crucible 7; selected for use in the test, a rotating disk 9 made of stainless steel with copper inserts is connected to the motor 10; an induction heating coil 14 is installed around the rotating disk 9, after which the housing 13 is hermetically sealed;

by means of the resistance heater 4, the crucible 7 is heated at a heating temperature of 260° C. and a heating rate of 15° C./min; the temperature is maintained for 10 minutes so that the metal material in the crucible 7 is completely melted;

by means of the electric motor 10, the speed of rotation of the specified rotating disk 9 is provided, which is 24000 rpm; then, the induction heating voltage of the induction heating coil 14 is set to 21 V, the induction heating current is 8 A, and the induction heating time is set to 10 minutes; surface

the high-speed rotating disc 9 is heated to a melting point of the metal material of more than 183°C;

a trapezoidal wave pulse signal is applied to the piezoelectric ceramic 1 and the frequency is set to 100 Hz; the piezoelectric ceramic 1 provides a downward displacement, which is transferred to the molten metal located in the area near the central hole of the crucible 7 by means of the transfer rod 3 and the pressure plate 5, as a result of which the molten metal is ejected from the central hole in the lower part of the crucible with the formation of identical drops 15; identical droplets 15 fall freely onto the high-speed rotating disk 9, while identical melt drops 15 first fall into the center of the rotating disk 9; since at this moment the centrifugal force is relatively small, the drops 15 will not immediately dissipate outward, but will spread around the rotating disk 9 in a circle; when they spread to a certain limit, where the centrifugal force is large enough, the spread metal under the action of centrifugal force on the rotating disk 9 will move in the form of streams to the edge of the rotating disk 9 and, finally, separate into small drops and fly off; small drops in the process of falling, ending up outside the container, harden and form metal powder 11, which falls on the collecting plate 12.

After obtaining the powder, the piezoelectric ceramic 1 is stopped from applying a trapezoidal wave pulse signal, that is, droplet ejection is stopped; stop the high-speed motor 10, causing the rotating disc 9 to stop rotating; turn off the resistance heater 4 and the induction heating coil 14, wait until the temperature drops to room temperature, and remove the metal powder 11 on the collecting plate 12; finally, the cavity inlet pipe 16 as well as the crucible first inlet pipe 2 and the crucible second inlet pipe 20 are closed, and a low vacuum of less than 5 Pa is created by means of a mechanical pump 10 in the crucible 7 and the housing 13 so that the equipment is in a vacuum state when not in operation. .

With reference to FIG. 3; from the image (b) it can be understood that the particle size of the powder obtained using the techniques of the prior art is relatively large and there are hemispherical particles, and the image (a) shows the powder obtained using the method according to the present invention, while the particles The powders are clearly characterized by reduced size, so that the grain size satisfies the requirements of the application, and the sphericity becomes high, while the morphology of the powder is also improved and there are no hemispherical particles.

With reference to FIG. 4; the image (b) shows the disk for spraying after spraying according to the technology known from the prior art; Since the wettability of the material of the sputtering disc and the material of the obtained metal powder is very low and the temperature of the rotating disc during the sputtering process is very low, the liquid will separate like a film, and a relatively thick hardening liquid film will appear on the sputtering surface, and the surface of this liquid film very coarse, which then does not contribute to the subsequent spraying of metal droplets and will seriously affect the spraying result and spraying efficiency. The image (a) shows the surface to be sprayed as a result of applying the method according to the present invention; it can be seen that the shape after spraying has become a shape with a noticeable streak, and the streak shape greatly improves the particle size reduction of the metal powder.

With reference to FIG. 5; image (a) shows lines of fluid flow in the middle part of a rotating disk; it can be understood from the image that the width of the liquid flow lines is less than 50 µm, which can explain that the fine size of the powder obtained by this method is due to the formation of thinner liquid streams in the form of fine streams. The image (b) shows lines of fluid flow in the region of the edge of a rotating disk; traces can be seen left after the departure of small drops, on the basis of which it can be said that the liquid metal, as a result of complete centrifugal atomization, is scattered over the edge.

Thus, according to the present invention, with regard to liquid metal, the traditional form of molten metal separation is eliminated and separation in the form of jets is carried out, which can only be carried out if the spray medium is an aqueous solution or an organic solution; Compared to existing centrifugal atomization technologies, streak atomized powder can be a major step forward in ultra-fine atomization; at the same time, low-melting ultrafine metal spherical powder can be obtained in this way, which is characterized by high sphericity, good fluidity and spreadability, no secondary droplets, and meets the requirements for use.

Finally, the following should be noted: all the above embodiments are intended solely to explain the technical solutions according to the present invention, and not to limit it; although the present invention has been described in detail by means of the embodiments discussed above, it should be understood by those skilled in the art that the technical solutions presented by means of the embodiments discussed above, they can still make changes or make equivalent substitutions with respect to part or all technical features presented in them; however, these changes or replacements do not mean that the essence of the respective technical solutions is outside the scope of the technical solutions in all embodiments of the present invention.

Claims (17)

1. A device for producing ultrafine low-melting spherical metal powder using drop spraying, comprising: a housing (13), a crucible (7) installed in the specified housing (13), and an area for collecting the powder, while the specified area for collecting the powder is located in the lower part of said housing (13); the specified crucible (7) is located above the specified area to collect the powder; the specified crucible (7) is an annular structure with internal and external elements, the Central line of which is the axis; the lower part of the inner containing cavity of the specified crucible (7) and the lower part of the outer containing cavity of the specified crucible (7) are provided with through central holes; between said lower part of the inner containing cavity and said lower part of the outer containing cavity, a space is provided for the passage of molten metal; in the inner containing cavity of the specified crucible (7) is the transmission rod (3), connected to the piezoelectric ceramics (1) located outside the specified housing (13); the specified transmission rod (3) at the lower end is provided with a pressure plate (5); the specified pressure plate (5) is located directly above the Central hole of the specified internal enclosing cavity; said body (13) is provided with crucible inlet pipes extending into said crucible (7); said housing (13) is further provided with a mechanical pump (17) and a diffusion pump (18) communicating with said crucible (7); said housing (13) is additionally provided with an inlet pipe (16) of the cavity and an air outlet valve (19) of the cavity; said powder collection area comprises a collecting plate (12) installed in the lower part of said housing, and a rotating disk (9) located above said collecting plate (12), connected to an electric motor (10) and intended for spraying metal particles; characterized in that said rotating disc (9) comprises a main body, a spray element (24) with a flat surface and an air vent (25); the specified main part is the main element of the T-shaped longitudinal section, consisting of the receiving part (22) in the upper part and the supporting part (23) in the lower part; the specified receiving part (22) on the upper surface is provided with a circular recess, coaxial with it in relation to the centers of the circle; wherein said main body is made of a material whose thermal conductivity is less than 20 W/(m⋅K); said element (24) for spraying with a flat surface is an element in the form of a round disk; the specified element in the form of a circular disc corresponds to the circular recess in the specified receiving part and is located in the specified circular recess fit with an interference fit; the specified element (24) for spraying with a flat surface is made of a material that provides a contact angle with the sprayed drops (15) less than 90°; the specified vent (25) is made passing through the specified receiving part (22) and the specified support part (23); the specified vent (25) upper side is in contact with the lower end surface of the specified element (24) for spraying with a flat surface; the specified vent (25) bottom side made in communication with the environment; an induction heating coil (14) is additionally provided around said rotating disk (9). 2. A device for producing ultrafine low-melting spherical metal powder using drop spraying according to claim 1, characterized in that the diameter of the central hole of the specified crucible (7) is in the range from 0.02 to 2.0 mm. 3. A device for producing ultrafine low-melting spherical metal powder using drop spraying according to claim 1, characterized in that the heating thickness of the specified induction heating coil (14) is in the range of 5-20 mm and it is connected to a frequency converter and a power supply with stabilization voltage, located outside the specified housing (13). 4. A device for producing ultrafine low-melting spherical metal powder using drop spraying according to claim 1, characterized in that in said device in the downward direction, said piezoelectric ceramics (1), said transfer rod (3), said crucible (7), said pressure plate (5), said rotating disc (9) and said induction heating coil (14) are arranged on the same axis. 5. The method of obtaining ultrafine low-melting spherical metal powder using drip spraying by means of a device according to any one of paragraphs. 1-4, characterized in that it includes the following steps:

loading of raw materials: the metal material to be melted is placed in the outer containing cavity of the crucible (7) located inside the housing (13) in the upper part, and hermetically sealed;

creating a vacuum: by means of a mechanical pump (17) and a diffusion pump (18), a vacuum is created in the specified crucible (7) and the specified housing (13) and filled with an inert protective gas of high purity to obtain a pressure of a predetermined value inside the housing (13);

resistive heating: based on the melting temperature of the raw material to be heated, the heating parameters are set by the resistive heater (4) and, by means of a thermocouple installed in the specified crucible (7), the temperature inside the specified crucible (7) is monitored in real time, maintaining the required temperature after complete melting metallic material;

induction heating: by means of an electric motor (10) high-speed rotation of the specified rotating disk (9) is provided with a pre-set rotation speed; then, by means of an induction heating coil (14), the upper surface of the high-speed rotating disk (9) is heated to a temperature which is higher than the melting point of the metal material;

obtaining particles: through the first inlet pipe (2) of the crucible and the second inlet pipe (21) of the crucible, installed on the specified body (13) and passing into the specified crucible (7), an inert protective gas of high purity is supplied to create in the specified crucible (7) back pressure, which leads to the filling of the molten metal of the central hole in the lower part of the specified crucible (7); a pulse signal is applied to the piezoelectric ceramics (1), while said piezoelectric ceramics (1) provides a downward displacement, and by means of a transmission rod (3) connected to said piezoelectric ceramics (1) and a pressure plate (5) located at the bottom of the specified transfer rod (3), the molten metal located in the area near the central hole is moved so that the molten metal is ejected from the bottom of the central hole with the formation of identical drops (15); identical drops (15) fall freely on the rotating disk (9), while identical drops (15) of the melt first fall into the center of the rotating disk (9); since at this moment the centrifugal force is small, the drops (15) will not immediately dissipate outward, but spread along the rotating disk (9) in a circle; when they spread, the centrifugal force becomes large, and the spread metal, under the action of centrifugal force on a rotating disk (9), moves in the form of streams to the edge of the rotating disk (9), and then splits into small drops and flies off; small drops in the process of falling, being outside the container, harden and form a metal powder (11), which falls on the collecting plate (12); and at the same time, the pressure plate (5) and the transfer rod (3) are returned to their original position and the molten liquid metal from the melting tanks in the specified crucible (7) passes into the region of the central hole;

collection of particles: a uniform spherical metal powder is collected by means of a collecting plate (12) installed at the bottom of said body. 6. A method for producing an ultrafine low-melting spherical metal powder using drop spraying according to claim 5, characterized in that the amount of said metal material loaded into said outer containing cavity is from 50 to 70% of the volume of said outer containing cavity. 7. A method for producing an ultrafine low-melting spherical metal powder using drop spraying according to claim 5, characterized in that the pressure after creating a vacuum in the specified housing (13) reaches 0.1 MPa and the holding time after complete melting of the metal material is 15-20 minutes . 8. A method for producing an ultrafine low-melting spherical metal powder using drip spraying according to claim 5, characterized in that the voltage range for induction heating by said induction heating coil (14) is 0-50 V, and the induction heating time is 5-15 minutes . 9. A method for producing an ultrafine low-melting spherical metal powder using drop spraying according to claim 5, characterized in that the rotation speed of said rotating disk (9) is from 10,000 to 50,000 rpm. 10. A method for producing an ultrafine low-melting spherical metal powder using drop spraying according to claim 5, characterized in that the voltage regulation range of the specified power supply with voltage stabilization is 0-50 V.

Images