CN105862034B - A kind of supersonic speed laser deposition coaxial powder feeding apparatus - Google Patents

Abstract

A kind of supersonic speed laser deposition coaxial powder feeding apparatus; including Laser output chamber, mounting cylinder, baffle, at least one protection letter shoot and at least one Laval nozzle; Laser output chamber includes laser via and laser head; laser via is integrally formed with laser head; the light-emitting window of laser via and laser head is coaxial, and transmissive mirror is equipped at the light-emitting window of laser head；Laser via is co-axially inserted the installation tube inner chamber after running through baffle center hole, and the bottom of mounting cylinder is against the baffle upper surface；The lower surface of baffle is bonded with the upper surface of laser head；In the Laval nozzle insertion laser head, the air inlet of Laval nozzle is connected to the high pressure gas powder conduit being stuck on baffle, and the laser that the central axes of all Laval nozzles are projected with Laser output chamber crosses.The method have the benefit that：Without gradually adjusting the relative position of Laval nozzle and laser head, and during spraying, the relative position of amyloid plaque and hot spot will not change.

Description

A supersonic laser deposition coaxial powder feeding device

technical field

The invention relates to a supersonic laser deposition coaxial powder feeding device.

Background technique

Cold spraying is also called cold gas dynamic spraying (Cold Gas Dynamic Spray, CGDS), which uses compressed gas (helium, nitrogen, air or mixed gas, etc.) as the acceleration medium to carry solid particles into the Laval nozzle (Lavalnozzle) A supersonic gas-solid two-phase flow is generated inside, and the solid particles collide with the surface of the substrate at a very high speed (greater than or equal to its critical deposition velocity) after acceleration, so that the particles and the substrate undergo strong plastic deformation at the same time to form a coating. New spraying technology. Compared with thermal spraying, the particles are heated at a lower temperature during the cold spraying process and still remain solid, and the solid particles are subjected to plastic rheology caused by "adiabatic shear instability" under conditions of extremely high stress, strain, and strain rate or through severe plasticity. Mechanical processes such as deformation achieve deposition on the workpiece surface. Therefore, during the spraying process, the particles are not prone to oxidation, burning, phase change, grain growth, etc., so the chemical composition and microstructure of the cold spray coating can be kept consistent with the raw materials, especially suitable for temperature-sensitive materials (such as nano materials, amorphous materials, etc.), easy-to-oxidize materials (such as aluminum, copper, titanium, etc.) and easy-to-phase-change materials (such as carbon-based composite materials, etc.)

Although cold spraying has its unique advantages in maintaining the original composition of coating materials and reducing thermal influence, the pure cold spraying technology still has the following disadvantages: 1) When depositing coating materials with high hardness, helium must be used as the The cost of the working carrier gas is high; 2) The effective deposition of particles and the preparation of stable high-quality coatings largely depend on the characteristics of the particles and the substrate material; 3) The bonding mechanism between the coating and the substrate is mainly mechanical bonding, so The bond strength of the deposited coating is low.

Aiming at the deficiencies of cold spraying technology, William O'Neill's research group at the University of Cambridge proposed Supersonic Laser Deposition (SLD), which synchronously introduces laser irradiation into the cold spraying process, and cools the cold through laser energy radiation. The thermal softening treatment of the sprayed particles, the substrate or both can instantly adjust and improve the mechanical properties of the material and the state of collision deposition, improve the thickness, deposition efficiency, density and bonding strength of the low-pressure cold spray coating, and then improve the performance of the coating. Due to the softening effect of laser heating on the sprayed particles and the substrate, the critical deposition speed of the sprayed particles is reduced to half of the original one, so the expensive helium can be replaced by the cheap nitrogen to achieve the deposition of high hardness materials, while reducing the cost. range of cold spray deposition materials.

The supersonic laser deposition experimental device is mainly composed of the following parts: laser, spray gun, mechanical arm, powder feeder, high-pressure gas source and other auxiliary equipment. Among them, the spray gun system is the core device. Spray particles are mixed with accelerating gas in the spray gun and accelerated to a certain speed, hitting the substrate to form a coating. A traditional supersonic laser deposition system is shown in FIG. 1 , a Laval nozzle 101 , a coating 102 , a substrate 103 , and a laser head 104 . Among them, the Laval nozzle and the laser head are respectively clamped on the mechanical arm, and the two are independent of each other. Supersonic powder particles are deposited in the area irradiated by the laser beam. Therefore, before the experiment is carried out, it is necessary to adjust the relative position of the laser head and the nozzle to ensure that the laser spot and the powder spot coincide. This makes the experimental process cumbersome and complicated. In addition, during the experiment, because the swing of the mechanical arm may affect the relative position of the light spot and the powder spot, resulting in the unevenness of the laser irradiation area during the deposition process, which affects the bonding between the coating and the substrate. Moreover, in the spray gun system of traditional supersonic laser deposition, only one Laval nozzle cooperates with the laser, which is not conducive to the full utilization of laser irradiation energy.

Therefore, it is necessary to develop an easy-to-operate multifunctional coaxial powder feeding device for supersonic laser deposition.

Contents of the invention

In view of the above-mentioned shortcomings in the traditional supersonic laser deposition spray gun system, the object of the present invention is to provide an easy-to-operate multi-functional coaxial powder feeding device for supersonic laser deposition.

A coaxial powder feeding device for supersonic laser deposition according to the present invention is characterized in that it includes a laser light exit cavity, a mounting cylinder, a baffle, at least one protective gas delivery pipe and at least one Laval nozzle. The laser light exit cavity includes a laser passage and a laser head, the laser passage is integrally formed with the laser head, the laser passage is coaxial with the light exit of the laser head, and the light exit of the laser head There is a light-transmitting mirror; the laser path passes through the central hole of the baffle plate and is coaxially inserted into the inner cavity of the installation cylinder, and the bottom of the installation cylinder is against the upper surface of the baffle plate; The lower surface of the baffle is attached to the upper surface of the laser head; the Laval nozzle is embedded in the laser head, and the air inlet of the Laval nozzle is stuck on the baffle The high-pressure gas powder delivery pipe on the top is connected, and the central axis of all Laval nozzles meets the laser light emitted from the laser light cavity; the shielding gas delivery pipe is embedded in the laser head, and the shielding gas The air inlet at the upper end of the conveying pipe protrudes from the upper surface of the baffle, and the air outlet at the lower end of the shielding gas conveying pipe communicates with the light outlet of the laser head at the bottom of the light-transmitting mirror.

The Laval nozzles are arranged circumferentially along the gas outlet of the laser head.

The Laval nozzle is divided into a straight section for connecting with the high-pressure gas powder delivery pipe, a constriction section and an expansion section as a throat, and the throat shape of the constriction section is circular, rectangular or Oval.

The light-transmitting mirror is sealingly connected with the inner wall of the air outlet of the laser head, and the central axis of the light-transmitting mirror coincides with the central axis of the laser light exit cavity.

The diameter of the laser spot emitted by the laser light exit cavity is larger than the diameter of the sprayed powder spot emitted by the Laval nozzle.

The Lava nozzles of the present invention can be two, three, four or five or even more, distributed on the top of the laser light output cavity; the powder and gas feeding controls of the Lava nozzles are independent of each other, and one or more can cooperate with each other Powder feeding; the spraying distance of Lava nozzles can be equal or not; the throat diameters of Lava nozzles can be the same or different.

The beneficial technical effects of the present invention are: 1) the Laval nozzle and the laser head are integrated in one device, which simplifies the experimental equipment;

2) There is no need to adjust the relative position of the Laval nozzle and the laser head successively, and the relative position of the powder spot and the light spot will not change during the spraying process;

3) The combination of multiple Laval nozzles and one laser beam is realized, which improves the utilization rate of laser energy;

4) The control of powder feeding and air feeding between multiple Laval nozzles is independent of each other, and powder feeding and air feeding can be selectively performed on certain nozzles, so that the powder feeding rate can be adjusted in a wide range;

5) The shape and size of the throats of multiple Laval nozzles can be the same or different, and the composite use of nozzles with the same or different parameters can be realized;

6) The type and size of deposited powder particles in multiple Laval nozzles can be the same or different, so that composite deposition of multiple materials can be realized simultaneously, which greatly enriches the matching methods of various powder particles.

Description of drawings

Fig. 1 is a structural schematic diagram of a traditional supersonic laser deposition system (101-Laval nozzle; 102-coating; 103-substrate; 104-laser head);

Fig. 2 is a structural representation of the present invention;

Fig. 3 is the schematic diagram that the present invention is provided with two identical circular Laval nozzles;

Fig. 4 is one of the schematic diagrams of nozzles and powder spot distribution on the laser light exit cavity of Fig. 3 (top view, the direction of the arrow represents the scanning speed direction, A represents powder spot I; B represents powder spot II);

Fig. 5 is the schematic diagram that the present invention is provided with two different Laval nozzles (wherein one throat shape is circular, and the other throat shape is square);

Fig. 6 is the second schematic diagram of the distribution of nozzles and powder spots on the laser light exit cavity of Fig. 5 (top view, the direction of the arrow represents the direction of scanning speed, A represents powder spot I; C represents powder spot III);

Fig. 7 is the schematic diagram that the present invention is provided with three Laval nozzles (wherein two throat pipe shapes are circular, and another throat pipe shape is oval);

Fig. 8 is the second schematic diagram of the distribution of nozzles and powder spots on the laser light exit cavity of Fig. 7 (top view, the direction of the arrow represents the direction of scanning speed, A represents powder spot I; B represents powder spot II; D represents powder spot IV).

Detailed ways

Further illustrate the present invention below in conjunction with accompanying drawing

Referring to the attached picture:

Embodiment 1 A supersonic laser deposition coaxial powder feeding device according to the present invention includes a laser light exit cavity 1, an installation cylinder 2, a baffle plate 3, at least one protective gas delivery pipe 4 and at least one Laval nozzle 5 The laser light exit cavity 1 includes a laser passage 11 and a laser head 12, the laser passage 11 is integrally formed with the laser head 12, and the laser passage 11 is the same as the light exit of the laser head 12 axis, and the light outlet of the laser head 12 is provided with a light-transmitting mirror 6; the laser path passes through the center hole of the baffle plate 3 and then coaxially inserts into the inner cavity of the installation cylinder 2, and the The bottom of the installation cylinder 2 is against the upper surface of the baffle 3; the lower surface of the baffle 3 is attached to the upper surface of the laser head; the Laval nozzle 5 is embedded in the laser In the head 12, the air inlet of the Laval nozzle 5 communicates with the high-pressure gas powder conveying pipe 7 stuck on the baffle plate 3, and the central axis of all the Laval nozzles 7 is connected with the laser exit cavity 1. Laser intersection; the shielding gas delivery pipe 4 is embedded in the laser head 12, and the upper air inlet of the shielding gas delivery pipe 4 protrudes from the upper surface of the baffle plate 3, and the shielding gas delivery pipe 4 The gas outlet at the lower end of the tube 4 communicates with the light outlet of the laser head 12 located at the bottom of the transparent mirror 6 .

The Laval nozzles 5 are arranged circumferentially along the gas outlet of the laser head 12 .

The Laval nozzle 5 is divided into a straight section for connecting with the high-pressure gas powder delivery pipe 7, a constriction section and an expansion section as a throat, and the throat shape of the constriction section is circular, Rectangular or oval.

The light-transmitting mirror 6 is sealingly connected with the inner wall of the air outlet of the laser head 12 , and the central axis of the light-transmitting mirror 6 coincides with the central axis of the laser light exit cavity 1 .

The diameter of the laser spot emitted by the laser light exit cavity 1 is larger than the diameter of the spray powder spot emitted by the Laval nozzle.

The Lava nozzles of the present invention can be two, three, four or five or even more, distributed on the top of the laser light output cavity; the powder and gas feeding controls of the Lava nozzles are independent of each other, and one or more can cooperate with each other Powder feeding; the spraying distance of Lava nozzles can be equal or not; the throat diameters of Lava nozzles can be the same or different.

Embodiment 2 In this example, the laser head is provided with two Laval nozzles, and the shape of the shrinkage section of the Laval nozzle is circular; The laser spot diameter is greater than the diameter of the powder spot, and two circular Laval nozzles ( 51, 52) Symmetrically distributed in the laser head of the laser light exit cavity with respect to the axis of the light exit cavity (as shown in Figure 3), two beams of powder-gas two-phase flow in the Laval nozzle hit the substrate 7 area synchronously heated by the laser at the same time. The powder spot I of the nozzle 51 and the powder spot II of the nozzle 52 are adjacent to each other but not overlapped (distributed along the direction of scanning speed from left to right, as shown in FIG. 4 ), and are located on the same horizontal line. Compared with the traditional spraying process, after a single spraying, the single-layer coating is composed of two overlapping deposition layers, which greatly increases the width of a single spraying.

Embodiment 3 In this example, the laser head is provided with two Laval nozzles, and the shape of the shrinkage section of the Laval nozzle is a circle and a square; the laser spot diameter is greater than the powder spot diameter, and the circular Laval nozzle The pipe 51 and the square Laval nozzle 53 are asymmetrically distributed on the head of the laser light exit cavity with respect to the axis of the light exit cavity, (as shown in Figure 5), and the two beams of powder-gas two-phase flow in the nozzle impinge on the laser synchronously heated base area. The powder spot I of the nozzle 51 and the powder spot III of the nozzle 53 are adjacent but not overlapped (distributed in tandem along the scanning speed direction, as shown in FIG. 6 ). Compared with the spraying process of the traditional spray gun system, after a single spraying, the single-layer coating is composed of two deposited layers, which increases the thickness of the single-spraying coating and realizes the compound laser deposition of nozzles with different shapes

Embodiment 4 In this example, the laser head is provided with three Laval nozzles, and the shape of the shrinkage section of the Laval nozzles is two circles and one oval; the laser spot diameter is greater than the powder spot diameter, and the circular Laval The nozzles (51, 52) and the third elliptical Laval nozzle (54) are unevenly distributed around the head of the laser light exit cavity (as shown in Figure 7), and the three powder-gas two-phase flows in the nozzle Simultaneously strikes the substrate area which is heated synchronously by the laser. The powder spot I of the nozzle 51 and the powder spot II of the nozzle 52 are adjacent to each other but not overlapping (distributed along the direction of scanning speed, one left and one right), and the powder spot IV of the third nozzle 54 and the powder spot IV of the nozzles (51, 52) Ⅰ and Ⅱ overlap at the same time, as shown in Figure 8. The powder and gas of the three nozzles are conveyed by the same group of high-pressure air source and powder feeder, but there are independent control systems, and one nozzle, two nozzles or three nozzles can be fed separately or simultaneously according to the needs. . Compared with the spraying process of the traditional spray gun system, after a single spraying, a single coating, overlapping coating or overlapping coating with heterogeneous shapes can be obtained, which can not only increase the width of a single deposition, but also increase the thickness.

The content described in the embodiments of this specification is only an enumeration of the implementation forms of the inventive concept. The protection scope of the present invention should not be regarded as limited to the specific forms stated in the embodiments. The protection scope of the present invention also includes those skilled in the art. Equivalent technical means conceivable according to the concept of the present invention.

Claims (3)

1. a kind of supersonic speed laser deposition coaxial powder feeding apparatus, it is characterised in that：Including Laser output chamber, mounting cylinder, baffle, extremely A few protection letter shoot and at least one Laval nozzle, the Laser output chamber include laser via and laser head, The laser via is integrally formed with the laser head, and the light-emitting window of the laser via and the laser head is same Axis, and transmissive mirror is equipped at the light-emitting window of the laser head；After the laser via runs through the baffle center hole It is co-axially inserted the installation tube inner chamber, the bottom of the mounting cylinder is against the baffle upper surface；The baffle Lower surface is bonded with the upper surface of the laser head；In the Laval nozzle insertion laser head, the drawing The air inlet of Wa Er jet pipes is connected to the high pressure gas powder conduit being stuck on baffle, the central axes of all Laval nozzles The laser projected with Laser output chamber crosses；In the protection letter shoot insertion laser head, and it is described Protect letter shoot upper end air inlet from baffle upper surface stretch out, the lower end gas outlet of the protection letter shoot be located at The light-emitting window of the laser head of transmissive mirror bottom is connected to；Light-emitting window week of the Laval nozzle along the laser head To arrangement, and the laser spot diameter that the Laser output chamber projects is more than the spray coating powder that the Laval nozzle projects Last amyloid plaque diameter.

2. a kind of supersonic speed laser deposition coaxial powder feeding apparatus as described in claim 1, it is characterised in that：The Lavalle Jet pipe is divided into the direct tube section for being connect with the high pressure gas powder conduit, contraction section and expansion segment as throat, The throat shape of the contraction section is round, rectangle or ellipse.

3. a kind of supersonic speed laser deposition coaxial powder feeding apparatus as described in claim 1, it is characterised in that：The transmissive mirror It is connect with the light-emitting window inner wall sealing of the laser head, and the center of the central shaft of transmissive mirror and the Laser output chamber Overlapping of axles.