CN203886770U - Laser-assisted cold spraying nozzle device - Google Patents

Abstract

The utility model discloses a laser-assisted cold spray nozzle device. One side of the nozzle throat is a nozzle constriction section, and the other side of the nozzle throat is a nozzle expansion section. The nozzle is provided with a high-pressure gas inlet and a The light-transmitting window for the laser beam to enter, the light-transmitting window is set away from the axis of the nozzle, the nozzle is provided with a reflector A on the nozzle contraction section, and the nozzle is provided with a powder inlet, a reflector B, a reflector C and a reflector on the side of the nozzle expansion section Mirror D, the laser beam entering from the light-transmitting window is reflected by mirror A, mirror D, mirror B and mirror C in sequence inside the nozzle and then ejected from the expansion section of the nozzle. The powder inlet is located between mirror D and mirror B between. In this technical solution, the laser beam and the nozzle axis are injected into the reflector in the nozzle at a certain angle, and the beam is reflected by the reflector on the inner wall of the nozzle for many times, and finally irradiated on the substrate, which can uniformly pre-heat the gas, powder and substrate inside the nozzle. hot.

Description

A laser-assisted cold spray nozzle device

technical field

The utility model relates to a laser-assisted cold spraying nozzle device, in particular to a supersonic nozzle device for laser cold spraying.

Background technique

Cold spraying, also known as cold gas dynamic spraying (Cold Gas Dynamic Spray, CGDS), was proposed by former Soviet scientists in the middle and late 1980s. It is a spraying technology based on the principle of aerodynamics. Its principle is to use high pressure The gas (nitrogen, helium, air, or mixed gas, etc.) carries the powder particles into the high-speed airflow, and the supersonic gas-solid two-phase flow is generated through the zoom tube (Laval tube), and the powder particles are accelerated by the supersonic nozzle in a solid state. It collides with the substrate at a very high speed, and deposits on the surface of the substrate to form a coating by generating strong plastic deformation. Unlike thermal spray, which relies on thermal or chemical energy, cold spray relies more on the kinetic energy of the particles. Therefore, this technology has the following advantages: 1) The spraying heating temperature is much lower than its melting point, and the particles basically do not have oxidation, burning loss and grain growth. It is suitable for spraying of temperature-sensitive materials such as nanocrystalline and amorphous materials, oxidation-sensitive materials such as Cu and Ti, and phase-change-sensitive materials such as carbide composite materials. 2) The thermal influence of the coating on the substrate is small, which reduces the thermal stress between the coating and the substrate. The residual stress between coatings is small and mainly compressive, which is beneficial to obtain thicker and denser coatings. 3) High spraying efficiency and low porosity. 4) Spraying powder can be recycled and reused, which is economical and environmentally friendly. Cold spraying technology is of great significance for expanding the field of thermal spraying, and it has opened up a new way for the application of surface engineering technology. It has been widely used in the preparation of various functional coatings, nano-coatings, automobile manufacturing, repair and remanufacturing of mechanical parts, aerospace and other fields.

By the end of the 1990s, researchers began to carry out research on laser-assisted cold spraying technology. Laser-assisted cold spraying is a new type of spraying and remanufacturing technology, its principle is shown in Figure 1, high-pressure gas source 101, powder feeder 102, Lava nozzle 103, test box 104, laser 105, pyrometer 106, substrate 107 , coating 108, powder recovery device 109. It combines a supersonic powder beam with laser heating of the deposition area. Laser-assisted cold spraying retains the advantages of cold spraying: solid-state deposition, high remanufacturing rate, and deposition on a range of substrates, and has wider application prospects than cold spraying. The laser is irradiated on the substrate to soften the substrate, so the coating of difficult-to-deposit materials can be prepared, and the scope of use of materials and substrates can be expanded; the introduction of laser can eliminate the use of gas preheating devices, reduce the consumption of compressed gas, and Cheap compressed air can be used instead of nitrogen or argon, which reduces the production cost of the process; laser softening treatment of particles or substrates can instantly adjust and change the mechanical properties of the material, increase its plastic flow, and improve the state of particle collision deposition , improve the thickness, deposition rate, compactness and bonding strength of the powder coating, and the prepared coating is superior to the cold spray coating.

In the European patent GB2439934A, a laser-assisted cold spray nozzle with a simple structure is proposed. In this nozzle, the laser light path is coaxial with the nozzle, and the laser spot is slightly smaller than the diameter of the nozzle throat. When working, the laser irradiates into the nozzle through the window made of special materials and finally irradiates on the substrate. The nozzle passes through the high-pressure gas all the way, and the powder to be sprayed all the way. The two reach supersonic speed in the Laval nozzle, and the solid The forms impinge on the substrate to form a coating. During the whole process, the laser not only heats the gas, powder particles, but also heats the substrate, so that the powder and the substrate are softened at the same time, thus greatly improving the deposition rate and bonding strength. However, the powder in the nozzle enters the throat from the constriction section, and the diameter of the throat is usually only a few millimeters. For metal powder materials with low melting point and softness, it is easy to stick to the throat of the nozzle under the irradiation of the laser, and it is easy to cause nozzle damage after working for a long time. Blockage, and the requirement for spot diameter is high, must be smaller than nozzle throat diameter.

U.S. Patent US20110300306A1 also proposes a laser-assisted cold spray nozzle device, which also adopts the method that the laser light path is coaxial with the nozzle. In this patent, the powder particles are fed by the expansion section of the nozzle, thus avoiding the phenomenon that the powder sticks to the throat due to heating and softening. However, the common disadvantage of the laser-assisted cold spray nozzle with the coaxial laser and powder is that the laser heats the particles and the carrier gas in the nozzle more unevenly, and there is a phenomenon of more heat in the middle and less heat on both sides. After deposition, the coating is thick in the middle and thin on both sides, and the powder Utilization is low.

At present, the laser-assisted cold spraying technology mainly uses the laser side irradiation method, and the nozzle is the nozzle used for pure cold spraying. Chinese invention patent CN101153393A discloses a cold-air dynamic spraying method containing laser irradiation. While spraying, an elliptical laser spot is irradiated directly in front of the circular spray spot. This method can significantly reduce the critical velocity of particles in the cold spraying process and improve the bonding efficiency. However, when the laser spot is irradiated sideways, only the substrate is preheated. For some hard particles, the carrier gas still needs to be preheated in the nozzle to make the powder finally deposit on the substrate, and the disadvantages of large gas consumption have not been resolved.

Contents of the invention

In order to solve the above-mentioned technical problems, the purpose of this utility model is to provide a laser-assisted cold spraying nozzle device. The laser beam is injected into the reflector in the nozzle at a certain angle with the axis of the nozzle, and the beam passes through the reflector on the inner wall of the nozzle multiple times. Reflected, and finally illuminated on the substrate. The device can evenly preheat the gas, powder and matrix inside the nozzle, and can cancel the carrier gas preheating device.

In order to achieve the above-mentioned purpose, the utility model adopts the following technical solutions:

A laser-assisted cold spray nozzle device, including a nozzle, one side of the nozzle throat is a nozzle constriction section, the other side of the nozzle throat is a nozzle expansion section, and the nozzle is provided with a high-pressure gas inlet and a laser power supply on one side of the nozzle constriction section. The light-transmitting window where the beam enters, the light-transmitting window is set away from the axis of the nozzle, the nozzle is provided with a reflector A on the nozzle constriction section, and the nozzle is provided with a powder inlet, reflector B, reflector C and reflector D on the side of the nozzle expansion section , the laser beam entering from the light-transmitting window is reflected by mirror A, mirror D, mirror B and mirror C in sequence inside the nozzle, and then ejected from the expansion section of the nozzle. The powder inlet is located between mirror D and mirror B.

Preferably, the high-pressure gas inlet is perpendicular to the nozzle axis, and the powder inlet is perpendicular to the nozzle axis.

Preferably, the reflector A and the reflector D are integrally fixedly connected to the nozzle, and the reflector B and the reflector C are detachably mounted on the nozzle.

Preferably, the mirror A, the mirror D, the mirror B and the mirror C are plane mirrors or concave mirrors.

The incident angle of the above-mentioned laser beam should be between 0° and half of the nozzle convergence angle. The installation positions of the light-transmitting window and the mirrors A, B, C, and D are determined by the beam reflection angle relationship. The mirror A must be installed In the section, mirror B is installed after the throat and before the powder feeding inlet, while mirrors B and C are installed after the powder feeding inlet. Preferably, the incident angle of the laser beam (the angle between the incident laser beam and the nozzle axis) is 1° to 10°, and the shrinkage angle of the nozzle shrinkage section (the angle between two shrinking inner walls that are arranged opposite to the nozzle axis) Angle) is 30° to 45°, and the expansion angle of the nozzle expansion section (the angle between the two expansion inner walls set opposite to each other with the nozzle axis as the center) is 10° to 12°.

Because the utility model adopts the above technical scheme, the laser emits a laser beam at a specific angle to the nozzle axis during operation. The beam passes through the window and enters the nozzle to irradiate on the reflector A. The beam is reflected by reflectors D, B and C. Finally, it is irradiated on the substrate. At the same time, the high-pressure gas enters the nozzle through the gas inlet and is accelerated by the Laval nozzle to reach supersonic speed and carry the powder flow from the powder inlet into the expansion section of the nozzle. The laser beam reaches the substrate in a wide range. The gas, powder particles and substrate in the nozzle are heated to soften the powder and substrate, which is conducive to the deposition of powder particles on the substrate to form a high-performance coating. The laser-assisted cold spraying nozzle can preheat the gas, powder particles and substrate in the nozzle, and the preheating is uniform, the gas heating device can be eliminated, and the shape and diameter of the spot can be flexibly adjusted without limitation. The powder is injected from the expansion section, which avoids the occurrence of clogging of the nozzle throat.

Description of drawings

Fig. 1 is a structural schematic diagram of a laser cold spraying system in the prior art.

Fig. 2 is a structural representation of the utility model;

1-laser, 2-laser beam, 3-light-transmitting window, 4-nozzle, 5-mirror A, 6-powder inlet, 7-mirror B, 8-powder, 9-coating, 10-substrate, 11 - reflector C, 12 - nozzle expansion section, 13 - reflector D, 14 - nozzle throat, 15 - nozzle contraction section, 16 - high pressure gas inlet, 17 - nozzle axis.

Detailed ways

Below in conjunction with accompanying drawing, specific embodiment of the present utility model is described in detail.

Example 1:

A kind of laser-assisted cold spraying nozzle device as shown in Figure 2, comprises nozzle 4, and one side of nozzle throat 14 is nozzle contraction section 15, and the other side of nozzle 4 throat 14 is nozzle expansion section 12, and nozzle 4 is in One side of the nozzle constriction section 15 is provided with a high-pressure gas inlet 16 and a light-transmitting window 3 for the laser beam 2 to enter. The light-transmitting window 3 is set away from the nozzle axis 17. The powder inlet 6, reflector B7, reflector C11 and reflector D13 are arranged on the side of the nozzle expansion section 12, and the laser beam 2 entering from the light-transmitting window 3 passes through the reflector A5, reflector D13,

The reflector B7 and the reflector C11 are reflected and ejected from the nozzle expansion section 12, and the powder inlet 6 is located between the reflector D13 and the reflector B7. The high-pressure gas inlet 16 is perpendicular to the nozzle axis 17 , and the powder inlet 6 is perpendicular to the nozzle axis 17 . The reflector A5 and the reflector D13 are integrally fixedly connected with the nozzle 4 , and the reflector B7 and the reflector C11 are detachably mounted on the nozzle 4 . The reflector A5, the reflector D13, the reflector B7 and the reflector C11 are plane mirrors or concave mirrors.

A laser-assisted cold spraying method, including a laser-assisted cold spraying nozzle device as described above, high-pressure gas enters the interior of the nozzle 4 from the high-pressure gas inlet 16, and passes through the nozzle contraction section 15, nozzle throat 14 and nozzle expansion section 12 in sequence Then spray to the substrate 10; the powder particles enter the nozzle expansion section 12 from the powder inlet 6, and then are carried by the high-pressure gas to form a powder flow 8 and spray to the substrate 10; the laser beam 2 generated by the laser 1 enters the interior of the nozzle 4 from the light-transmitting window 3, and sequentially After being reflected by the mirror A5, the mirror D13, the mirror B7 and the mirror C11, it is irradiated on the substrate 10, and the laser beam 2 passes through the powder flow 8 to preheat the powder particles during the reflection process, and the laser beam 2 is on the surface of the substrate 10. The irradiated area overlaps with the injection area of the powder flow 8 on the surface of the substrate 10 .

In this embodiment, the incident angle of the laser beam 2 is 1°-10°, the contraction angle of the nozzle constriction section 15 is 30°-45°, and the expansion angle of the nozzle expansion section 12 is 10°-12°. The mirrors 5 and 13 are directly embedded in the supersonic nozzle 4 and integrated with the nozzle, while the mirrors 7 and 11 are detachable and fixed on the nozzle 4 by screws.

The laser 1 emits a laser beam 2 at a specific angle to the X-axis (nozzle axis 17). The beam passes through the window 3 and enters the nozzle to irradiate the reflector 5. The beam is reflected by the reflectors 13, 7 and 11 and finally irradiates the substrate. At the same time, the high-pressure gas enters the interior of the nozzle through the gas inlet 16, accelerates through the Laval nozzle, reaches supersonic speed and carries the powder flow 8 from the powder inlet 6 into the nozzle expansion section 12, and the laser beam is heated in a wide range during the process of reaching the substrate The gas, powder particles and substrate in the nozzle are softened, and the powder and substrate are softened, which is conducive to the deposition of powder particles on the substrate 10 to form a high-performance coating 9 . The laser-assisted cold spraying nozzle can preheat the gas, powder particles and substrate in the nozzle, and the preheating is uniform, the gas heating device can be eliminated, and the shape and diameter of the spot can be flexibly adjusted without limitation. The powder of the device is fed from the expansion section of the supersonic nozzle, which greatly reduces the powder feeding pressure, saves costs, and can avoid the nozzle throat from sticking or even clogging. The mirrors 7 and 11 fixed on the nozzle by screws are detachable. After a period of laser cold spraying, the mirrors 7 and 11 can be removed and wiped with special mirror-cleaning paper.

It should be emphasized that: the above are only preferred embodiments of the present utility model, and are not intended to limit the present utility model in any form. Any simple modification, equivalent change and Modifications still belong to the scope of the technical solution of the utility model.

Claims (4)

1. A laser-assisted cold spray nozzle device, characterized in that it includes a nozzle (4), one side of the throat (14) of the nozzle (4) is a nozzle contraction section (15), and the throat of the nozzle (4) (14) The other side of the nozzle is the nozzle expansion section (12). The nozzle (4) is provided with a high-pressure gas inlet (16) and a light-transmitting window (3) for the laser beam (2) to enter on the side of the nozzle contraction section (15). The light window (3) is set away from the nozzle axis (17), the nozzle (4) is provided with a reflector A (5) on the nozzle constriction section (15), and the nozzle (4) is provided with powder on the side of the nozzle expansion section (12) Inlet (6), mirror B (7), mirror C (11) and mirror D (13), the laser beam (2) entering from the light-transmitting window (3) passes through the mirrors in sequence inside the nozzle (4) A (5), reflector D (13), reflector B (7) and reflector C (11) are reflected and ejected from the nozzle expansion section (12), and the powder inlet (6) is located at reflector D (13) and reflector Between Mirror B (7). 2. A laser-assisted cold spray nozzle device according to claim 1, characterized in that the high-pressure gas inlet (16) is perpendicular to the nozzle axis (17), and the powder inlet (6) is perpendicular to the nozzle axis (17) . 3. A laser-assisted cold spray nozzle device according to claim 1, characterized in that the reflector A (5) and the reflector D (13) are fixedly connected with the nozzle (4), and the reflector B ( 7) and mirror C (11) are detachably mounted on the nozzle (4). 4. A laser-assisted cold spray nozzle device according to claim 1, characterized in that the mirror A (5), mirror D (13), mirror B (7) and mirror C (11 ) is a plane mirror or a concave mirror.