KR20060097411A - Nozzle for cold spray and cold spray apparatus using the same - Google Patents

Abstract

The present invention relates to a cold spray nozzle and a cold spray device using the same, in particular the neck portion connected to the convergence end of the cross-sectional convergence and the convergence end of the convergence inlet and the end of the neck A hollow nozzle portion having an outlet portion connected thereto, and an injection tube positioned inside the converging inlet portion and disposed so that an end injection hole is located within the neck portion or an outlet portion passing through the throat portion, It relates to a cold spray nozzle and a cold spray device using the same, characterized in that the outlet end flow rate is 300 to 1,200 kPa. Therefore, it is possible to minimize the clogging of the nozzle when the powder coating of the soft material, and to prevent the wear of the nozzle when the powder coating of the high-hardness material, the nozzle can be used for a long time, easy to apply to mass production, High quality coatings can be applied to reduce manufacturing costs during mass production. In addition, it is possible to control the speed of the powder by adjusting the position of the injection tube without adjusting the flow rate of the supply gas has the advantage of easy process change.

Cold Spray, Nozzle

Description

NOZZLE FOR COLD SPRAY AND COLD SPRAY APPARATUS USING THE SAME}

1 to 3 are cross-sectional views showing cross-sectional views of embodiments of the cold spray nozzle of the present invention.

4 is a schematic view showing a conventional cold spray nozzle and its system.

5 is a view showing a numerical analysis result of the flow characteristics in the conventional cold spray nozzle of FIG. (Unit: m / s)

6 is a view showing the numerical results of the flow characteristics when the position of the injection port of the injection tube in the conventional cold spray nozzle of FIG. (Unit: m / s)

7 is a perspective view of a flow field model for numerical analysis of flow characteristics in one embodiment of a cold spray nozzle of the present invention.

8 is a view showing a numerical analysis result of the flow characteristics in the cold spray nozzle in the embodiment of FIG. (Unit: m / s)

9 is a view showing the numerical results of the flow characteristics when the position of the injection port of the injection tube in the cold spray nozzle of the present invention of FIG. (Unit: m / s)

10 is a system schematic diagram of a cold spray apparatus to which a cold spray nozzle of the present invention is applied.

Explanation of symbols on the main parts of the drawings

2: convergence part 4: Throat part

6: outlet 8: outlet

10 nozzle part 12 injection hole

20: injection tube

The present invention relates to a cold spray nozzle and a cold spray device using the same, to minimize the clogging of the nozzle during the powder coating of a soft material, and to a powder coating of a high hardness material Nozzle wear can be prevented, so the nozzle can be used for a long time, so it is easy to apply to mass production, and high-quality coating can be applied for a long time, thus reducing the manufacturing cost during mass production, and pressurizing the powder feeder with high pressure. It is possible to construct a low-cost facility without the need for a device. In addition, it is possible to control the speed of the powder by adjusting the position of the injection tube without adjusting the flow rate of the supply gas. It relates to a cold spray device using the same.

Cold spray coating is a method of coating the surface of the deposit by spraying the powder at a normal temperature or a low temperature which is relatively unheated using a supersonic carrier gas, and is accelerated by a supersonic jet stream (300 to 1200 m / s). Small particles (1 to 50 μm) are coated on a metal or ceramic substrate, and the accelerated gas temperature, gas velocity, particle size, and the like are applied as process variables for coating.

In particular, since the particles are coated by colliding the particles accelerated at high speed on the unheated substrate, the coating efficiency varies depending on the material to be coated, and the coating efficiency increases as the speed of the accelerated particles increases. It shows a rapidly increasing characteristic.

The basic requirements for coating with supersonic cold spray coating are as follows: a) The temperature of the jet stream must always be lower than the melting or softening point of the accelerated particles. b) The particles to be accelerated should be in the range of 1 to 50 μm. c) The speed of the particles should be between 300 and 1,200 m / s depending on the particle material and size. In fact, the particles are coated with the help of a supersonic jet stream between Machs 2 and 4 and 1 to 3 MPa, the type of gas using air, nitrogen, helium, mixed gases, etc. The particles to be accelerated also have to exceed the critical velocity in order for the coating to be possible (V> Vcrit).

For this reason, in order to increase the velocity of the gas to increase the flow rate by increasing the temperature of the gas, and to provide a supersonic carrier gas, a conventional De Laval type nozzle is used as a nozzle. This is a technique known from US Pat. No. 6,139,913 and has a configuration as shown in FIG. However, this de Laval type nozzle (convergence-diffusion nozzle) is mixed with a gas / powder mixture in which the gas supplied from the left side is mixed with the gas supplied from the left side to the carrier gas supplied from the lower side, as shown in FIG. And then accelerate it.

Thus, the gas / powder mixture thus supplied is gradually accelerated through the convergence portion of the convergence-diffusion nozzle to reach the speed of sound at the neck as shown in FIGS. 5 to 6, and after reaching the speed of sound, To keep the weight constant, the trailing part of the nozzle is in diffusion form. This increases the velocity of the gas leaving the throat area and finally at supersonic speed. Gases that move at supersonic speeds have a faster rate of expansion outward than those that accelerate backwards. This is because the gas dissipates energy in the circumferential direction as the gas is compressed in the axial flow direction. Shrink-diffusion nozzles use this principle to generate the thrust needed to propel the gas / powder mixture in the nozzle at supersonic speed.

However, in the case of the method shown in FIG. 4, since the gas / powder mixture is introduced before the throat, the powder undergoes a process that must be injected through the throat. In this case, the injected powder is a relatively soft powder such as aluminum. There is a problem that the powder is coated on the neck and the neck is blocked in a short time, so that coating cannot be carried out anymore, so that it is difficult to apply to mass production. When the injected powder is a hard powder such as nickel or superalloy, Since the speed at the neck is about the level of the speed of sound, the coating does not occur, but severe wear occurs on the neck due to the powder collision, and the nozzle is damaged, and the flow rate is changed by changing the shape of the neck, thereby changing the process conditions.

In addition, in the case of coating using the apparatus as shown in FIG. 4, the pressure acting on the injection tube for injecting the gas / powder mixture supplied from the left side of the nozzle is supplied from the lower part of the nozzle to supply the carrier gas as a carrier gas. Since it must be higher than the pressure there is a problem to be provided with a separate pressurizing device.

In addition, as shown in FIGS. 5 and 6, when a known convergence-diffusion nozzle is used, the final outlet flow rate at the outlet end of the nozzle does not change even when the position of the injection tube for supplying the gas / powder mixture is changed. Can be observed. Therefore, if the flow rate is to be changed to change the process conditions, it is difficult to change the flow rate of the entire system.

In order to solve the problems of the prior art as described above, the present invention can minimize the phenomenon that the nozzle is clogged when the powder coating of the soft material, and can prevent the wear of the nozzle during the powder coating of the hard material, the nozzle for a long time It is an object of the present invention to provide a cold spray nozzle and a cold spray device using the same, which can be used for a long time, can be easily applied to mass production, and can be coated with high quality for a long time.

In addition, an object of the present invention is to provide a cold spray nozzle and a cold spray device using the same, which can control the speed of the powder injected from the outlet of the nozzle without adjusting the flow rate of the supply gas.

In addition, the present invention is not equipped with a pressure device in the gas / powder supply device can be configured inexpensive coating equipment, can be used without long-term maintenance economical cold spray nozzles that can reduce the initial cost as well as operating costs And to provide a cold spray device using the same.

In order to achieve the above object, the present invention

A hollow nozzle part comprising a converging inlet section having a converging cross section, a neck portion connected to the converging end of the converging inlet section, and an outlet portion connected to the end of the neck section, and located inside the converging inlet section. It includes a spray tube disposed to be located in the neck or the outlet portion past it, and provides a cold spray nozzle, characterized in that the outlet end flow rate of the powder at the outlet is 300 to 1,200 kPa.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The present invention relates to a nozzle for a cold spray, a converging inlet section (2) having a cross-sectional convergence and a throat (4) connected to the converging end of the converging inlet section (2) and the end of the neck (4) A hollow nozzle portion 10 consisting of an outlet portion 6 connected to the outlet portion, and located inside the converging inlet portion 2, the end injection hole 12 is the neck portion 4 or the outlet portion past it And an injection tube 20 disposed to be located in the 6, and characterized in that the flow rate of the outlet end 8 of the powder in the outlet 6 is 300 to 1,200 kPa.

A specific embodiment thereof is as shown in FIGS. 1 to 3, wherein the convergent inlet part 2 has a carrier gas supplied only to the gas except for the injection tube 20 to the sound velocity at the neck part 4. In order to ensure that it is composed of a convergence nozzle. Accordingly, the speed of the carrier gas reaches the speed of sound in the neck part 4, and the carrier gas from the neck part 4 is accelerated to 300 to 1,200 m / s because it passes through the outlet part 6 through which the flow is diffused. The gas / powder mixture supplied to the carrier gas through the injection tube 20 is injected into the outlet part 6 of the neck part 4 or the past, so that clogging due to the coating on the neck part 4 or the collision Wear does not occur. In addition, since the pressure in the region is relatively low because the injection in the high-speed zone, the gas / powder mixture is introduced into the nozzle by a kind of suction (suction) does not require a separate pressurization at the inlet end of the injection tube (20). Therefore, a pressurization device is unnecessary and a device can be comprised easily.

Preferably, the nozzle has a shape of the neck part 4 and the outlet part 6 converging the flow of the gas / powder mixture in which the gas drawn from the converging inlet part 2 is injected from the injection tube injection port 12. After the speed is made to be the speed of sound, the flow can be configured to diverge again. Through this, the flow rate of the gas / powder mixture can be increased from supersonic to 300 to 1,200 m / s, thereby increasing the speed of the powder at the outlet end 8, which is the end of the outlet 6.

That is, as shown in Figs. 8 to 9, the carrier gas passing through the neck 4 is accelerated by the converging inlet 2 to reach the sound velocity, and since the cross-sectional area is increased at the outlet 6, it diffuses. It can be seen that the area is accelerated to supersonic speed. In addition, the carrier gas contracts the flow of the gas / powder mixture coming out of the injection tube 20 as it expands, thereby converging the flow injected from the injection hole 12 of the injection tube 20. If the convergence is sufficient to accelerate the speed of the flow injected from the injection port 12 at the speed of sound, the flow is accelerated at the speed of sound, and then the divergence at the rear end of the outlet part 6 where the contraction effect of the carrier gas is reduced Since the flow injected into the injection hole 12 is also accelerated to supersonic speed, the entire flow injected from the nozzle is accelerated to supersonic speed so that the coating can be made with a high collision speed. That is, the carrier gas, which is the gas introduced into the converging inlet part 2, undergoes the process of general acceleration (convergence)-> sound velocity in the neck part-> supersonic acceleration (diffusion) according to the actual external shape of the nozzle, and the injection tube 20 The gas / powder mixture injected at) is subjected to the process of general acceleration (convergence by flow)-> neck formation and sound velocity by flow-> supersonic acceleration (by removing the influence of flow) by the diffusion flow of the carrier gas. Accelerated to obtain high speed.

This can be clearly seen by observing what is shown in Figs. 8 to 9, although the velocity decreases as the flow out of the injection tube 20 first exits the tube, but is pushed inward by the surrounding flow and narrows and contracts. As it converges, the speed increases to become the speed of sound, and then it can be clearly observed through the drawing that the speed is accelerated to the supersonic speed while expanding again.

In addition, the shape of the outlet 6 is not limited to the shape if the powder has a speed of 300 ~ 1,200 m / s, it can be configured in a variety of shapes, as shown in Figure 3 or divergent shape or 2 to 2 may be straight or the like, and a preferable specific example for generating the acceleration mechanism as described above is illustrated in FIGS. 1 and 2, and the outlet part 6 is hollow of the neck part 4. The hollow spray nozzle of the present invention may have a hollow cross-sectional area larger than that of the secondary cross-sectional area, and more preferably, the cold spray nozzle of the present invention has the shape of the neck 4 and the outlet 6 of the converging inlet 2. Gas introduced from the nozzle may converge the flow of the gas and powder mixture injected from the injection tube injection hole 12 so that the velocity becomes the speed of sound, and then the flow may diverge again. The. Such a configuration is obtained by modeling the flow field in the shape of FIG. 7 and as shown in FIGS. 8 to 9 as a result of numerical analysis using Fluent, which is a CFD analysis code for computer flow analysis.

In addition, in the cold spray nozzle of the present invention as described above, the neck portion 4 may be configured in a shape having a constant length in the same section as the minimum inner diameter portion of the nozzle. An example of this is as shown in Figures 2 to 3, through which the injection hole 12 of the injection tube can be located in the neck, neck, end or outlet of the neck, as shown in Figure 2, If necessary, the position can be changed during or after the process to the desired position.

Therefore, if necessary, the injection tube 20 may be configured to be movable along the axial direction of the nozzle so that the position of the injection hole 12 in the neck or the outlet can be changed. Through this, it is possible to control the blockage or deposition by the coating in the neck (4) or the outlet (6), or to adjust in a direction to reduce the wear caused by the collision, as shown in Figure 8 to 9 The final flow rate can be adjusted. That is, in FIG. 8 and FIG. 9, it can be seen that the powder velocity at the outlet end 8 is greatly changed as the protrusion amount (the distance from the neck end to the injection hole toward the outlet side) is changed. . Through this, it is possible to obtain an appropriate speed control in accordance with the type of powder or the mixing ratio by simply changing the position of the injection hole 12 of the injection tube, which is easy to control.

In addition, the cross section of the hollow part of the converging inlet part 2, the neck part 4, and the injection tube 20 and the cross section of the hollow part of the outlet part 6 are various shapes known in the art, depending on the process needs or the shape to be coated. It is possible to apply, preferably the cross section of the hollow portion of the converging inlet, neck and injection tube is circular, the cross section of the hollow portion of the outlet consists of a circle, square or rectangular to maintain the maintenance of the device and stable flow field Good for

In a specific example of the cold spray nozzle of the present invention, the outlet part has a hollow part cross-sectional area larger than the hollow part cross-sectional area of the neck part and is formed in a straight line, and when the total cross-sectional area of the converging inlet part is 900, The cross-sectional area of the flow path formed between the inside of the nozzle portion and the outside of the injection tube is 9 to 25, the cross-sectional area of the hollow portion of the injection tube is 0.25 to 8, the cross-sectional area of the outlet portion is 45 to 100, the convergent inlet is a convergent inlet It can be obtained by constructing a converging nozzle which allows the flow velocity to reach the speed of sound at the neck of the incoming gas introduced into the chamber.

In another specific and preferred case, the inner diameter of the neck portion is 5 mm, the inner diameter of the outlet portion is 7 mm, the outer diameter of the injection tube is 4.5 to 3.5 mm, the inner diameter of the injection tube is 3 to 1.5 mm, the injection The injection hole of the tube is positioned from 0 to 5 mm from the neck outlet end toward the outlet, more preferably the outer diameter of the injection tube is 4 mm, the inner diameter of the injection tube may be 2 mm, In addition to this, the injection tube may be changed in position along the axial direction of the nozzle in the injection hole in the neck or outlet, the position may be configured in the form of 0 to 5 mm from the neck end toward the outlet. .

Through this, while preventing the back pressure, which is the pressure acting inside the injection tube, can be prevented from being generated, a high speed flow can be obtained and smooth spraying can be achieved.

In another aspect, the present invention includes a cold spray nozzle of the present invention having the various shapes described above, a gas supply device connected to the converging inlet of the nozzle and a gas / powder mixture supply device connected to the injection tube. Provide a spray device.

Specific examples thereof are as shown in FIG. 10, and all the apparatuses applied to a general known cold spray apparatus may be applied together, but the pressure supplied to the injection tube is low, and thus, a separate injection tube input end. There is a feature that may not be provided with a pressing device.

In addition, using such a cold spray device can be carried out through the cold spray process through similar conditions to the known cold spray process. That is, by the cold spray device, the gas supplied from the gas supply device is accelerated at a sonic or supersonic speed, and the gas / powder mixture supplied from the gas / powder mixture supply device is mixed with the accelerated gas. A cold spray method is provided through the present invention which comprises spraying and coating a surface of a deposit by accelerating the powder to 300 to 1,200 kPa while maintaining a sufficiently low temperature of the gas / powder mixture. .

Process conditions in the above process can be applied to all similar conditions to the known cold spray process. However, since the injection is made by suction even when the pressure supplied to the injection tube is low, there is an advantage that the supply pressure can be kept low, and of course, the supply pressure can be adjusted higher as necessary.

In addition, the gas / powder mixture may have various ranges within a range of 1 to 99% by volume of the powder in the mixture, and the material used as the powder may be metal, alloy, metal or alloy mixture, organic matter, Various materials such as inorganic materials, organic materials or mixtures of inorganic materials or mixtures thereof are all possible, and these may be coated in a single layer or multiple layers in various combinations according to the required properties of the coating layer.

In addition, the present invention provides a coating, characterized in that the coating by the cold spray method. The adherend to be coated may be any of various materials such as metals, alloys, metal or alloy mixtures, organic materials, inorganic materials, organic materials or mixtures of inorganic materials, or mixtures thereof. It can be configured in combination.

According to the cold spray nozzle and the cold spray device using the same of the present invention as described above can minimize the clogging of the nozzle when the powder coating of a soft material, it is possible to prevent the wear of the nozzle when the powder coating of a high hardness material As the nozzle can be used for a long time without clogging or shape change, it is easy to apply to mass production.

In addition, the high-quality coating can be continuously performed for a long time, thereby reducing problems such as maintenance and operating costs, thereby reducing the production cost.

In addition, it is possible to easily control the speed of the powder injected from the outlet of the nozzle in accordance with the movement of the injection tube without adjusting the flow rate of the supply gas, it is easy to control the process, there is an advantage having a variety of process control means.

In addition, the gas / powder supply device is not provided with a pressurizing device, so that the coating equipment can be inexpensively configured, thereby reducing the initial cost, thereby having an economic effect.

The present invention described above is not limited to the above-described detailed description of the invention and the accompanying drawings, and those skilled in the art can be variously modified without departing from the spirit and scope of the present invention described in the claims below. Modifications and variations are also included within the scope of the invention.

Claims (13)

A hollow nozzle part comprising a converging inlet section having a converging cross section, a neck portion connected to the converging end of the converging inlet section, and an outlet portion connected to the end of the neck section, and located inside the converging inlet section. And a spray tube disposed to be located in the throat or through the outlet portion thereof, wherein the outlet flow velocity of the powder at the outlet portion is 300 to 1,200 kPa. The method of claim 1, The shape of the neck and the outlet is such that the gas introduced from the converging inlet converges the flow of the gas / powder mixture injected from the injection tube injection port so that the velocity becomes the speed of sound, and then the flow is diverged again. Cold spray nozzle characterized in that. The method of claim 1, And the outlet portion has a hollow portion cross-sectional area larger than the hollow portion cross-sectional area of the neck portion, and is configured in a straight line shape. The method of claim 1, And the outlet portion has a hollow portion cross-sectional area larger than the hollow portion cross-sectional area of the neck portion and is configured in a diverging type. The method of claim 3, The shape of the neck and the outlet is such that the gas introduced from the converging inlet portion converges the flow of the gas and powder mixture injected from the injection tube injection port so that the velocity becomes the speed of sound, and then the flow is diverged again. Cold spray nozzle characterized in that. The method of claim 1, The neck portion is a cold spray nozzle, characterized in that having a constant length in the same section as the minimum inner diameter portion of the nozzle. The method of claim 1, The spray tube is a cold spray nozzle, characterized in that the injection port is movable in the axial direction of the nozzle so that the position can be changed in the neck or outlet. The method of claim 1, The hollow section of the converging inlet, the neck and the injection tube has a circular cross section, the middle section of the outlet of the cold spray nozzle, characterized in that the circular, square or rectangular. The method of claim 3, When the total cross-sectional area of the converging inlet part is 900, the cross-sectional area of the flow path formed between the inside of the nozzle part and the outside of the injection tube in the neck is 9 to 25, the cross-sectional area of the hollow part of the injection tube is 0.25 to 8, and the cross-sectional area of the outlet part. Is a ratio of 45 to 100, wherein the converging inlet portion is a cold spray nozzle, characterized in that the convergence nozzle to reach the speed of sound in the neck of the incoming gas introduced into the converging inlet. The method of claim 1, The inner diameter of the neck portion is 5 mm, the inner diameter of the outlet portion is 7 mm, the outer diameter of the injection tube is 4.5 to 3.5 mm, the inner diameter of the injection tube is 3 to 1.5 mm, the injection hole of the injection tube is Cold spray nozzle, characterized in that located from 0 to 5 mm from the neck outlet end toward the outlet. Cold spray nozzle according to any one of claims 1 to 10; A gas supply device connected to a converging inlet of the nozzle; And Gas / powder mixture supply device connected to the injection tube Cold spray device comprising a. By the cold spray device of claim 11, the gas supplied from the gas supply device is accelerated at a sonic or supersonic speed, and the gas / powder mixture supplied from the gas / powder mixture supply device is mixed with the accelerated gas, And spraying the powder onto the surface of the adherend by accelerating the powder to 300 to 1,200 kPa while maintaining a sufficiently low temperature of the gas / powder mixture. The coating is coated by the cold spray method of claim 12.

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