Apparatus and method for depositing particles using a laser shock wave

Abstract

The invention relates to an apparatus (100) for selectively depositing by shock wave-induced spraying at least one particle (11) on a deposition surface (141) of a receiving substrate (140), said apparatus comprising: at least one laser source (101) configured to emit a laser beam (103), said laser beam being made up of a series of light pulses; a substrate carrier (130) on which the substrate (140) is fixed; and a shock wave-generating layer having a first surface (121) directed towards the laser beam and a second surface (122) directed towards the deposition surface (141) of the substrate. (120), and - an optical system (102) for focusing the laser beam towards a focal region on a first surface (121) of the production layer, - the second surface (122) having a plurality of cavities (123), each cavity containing at least one particle (11), - the laser beam is configured to generate a plasma (104) in the focal region on the first surface (121) of the production layer and a shock wave (105) propagating within the production layer (120) from the first surface to the second surface (122) of the production layer in order to spray the at least one particle (11) towards a deposition surface (141) of a substrate (140).

Description

Technical Field

[0001] The present invention relates to an apparatus for depositing particles by spraying using a laser shock wave. The present invention also relates to a method for depositing particles by spraying using a laser shock wave. More precisely, the method of the present invention consists in spraying each particle at the correct position and at the correct speed onto a specific area of interest, for the purpose of performing local surface treatment or functionalization of the target area, or for the purpose of creating a three-dimensional part by juxtaposing the deposition on the target area.

[0002] The present invention is particularly applicable to the creation of complex patterns on substrates or components on a microscopic and / or mesoscopic scale.

[0003] The present invention is also applicable to the targeted treatment of the surface of a coating by depositing by spraying each particle into the target area, for example to reduce the surface roughness of a component created by additive manufacturing.

[0004] The technical field of the present invention can be defined in a general manner as the field of laser-assisted spraying.

Background Art

[0005] It is known to use thermal spraying in many industrial fields such as automotive and aerospace to create deposits on substrates or components with thick coating layers having a thickness of several tens of micrometers to several hundreds, or even thousands of micrometers.

[0006] Figure 1 illustrates an example of a prior art thermal sprayer 1 with an inlet 2 for the material to be deposited and an inlet 3 for the energy source. Thermal spraying consists of introducing the material to be deposited, in the form of fine particles 7, into a gas 4 called the spraying gas. The gas is used to accelerate, heat, and transport the fine particles 7 towards the part to be coated, and the fine particles 7 will collide with the surface 6 of the substrate 5. These fine particles 7 are solid in their initial state but may be in a liquid, semi-molten, or even solid state after entering the spraying gas. Thus, the particles sprayed onto the substrate are fragmented and dispersed in various ways depending on the movement state of the particles, the state of the particles after entering the gas, the temperature of the particles, the material of the substrate, etc. The accumulation of particles on the substrate makes it possible to perform a coating by stacking these particles.

[0007] There are many methods for creating deposits by thermal spraying. One known technique is plasma spraying, which makes it possible to create metal or ceramic coatings. Plasma spraying is used more specifically for the deposition of ceramic coatings for coating parts of various geometries and sizes. Plasma spraying consists of injecting the material to be deposited, in the form of particles, into a plasma medium in which they are heated and accelerated towards the substrate. The coating is built by continuously stacking the molten or partially molten particles that collide with the substrate, and the particles are cooled by the substrate. The thickness of the coating is generally between 500 μm and 1 mm, including both ends.

[0008] Another known technique is the cold spray (CS) process. Metal powder is sprayed at very high speed onto the target, which is a new or repaired part, by a pressurized gas (up to 50 bar and 1100 °C). A drum tube (Delaval type) makes it possible to convert the temperature and pressure of the gas into kinetic energy, to drive its acceleration to supersonic speed, and to cool it to a temperature below 100 °C. The powder ejected into the high-pressure area of the spray nozzle is accelerated to a speed that can reach 1200 m / s. Due to the deformation of the particles upon impact, it is possible to obtain a coating with a very dense structure and very good adhesion.

[0009] In thermal spraying techniques, in order to obtain good mechanical adhesion of the coating layer on the substrate, it is necessary to prepare the surface using abrasive materials such as sand, corundum, and / or ice to create irregularities on the surface of the substrate so that the particles can be fixed. In order to define an adequate range of adhesion with respect to the specifications, generally, an adhesion test, which is a known method, is performed before deposition. In fact, if the adhesion is mediocre, it is not possible to deposit the particles on the surface of the substrate during the deposition period, or the resulting coating may easily come off, for example, during the manufacturing period of the part. The surface preparation techniques may result in residues on the surface of the substrate and are therefore not suitable for all substrates or all parts.

[0010] Furthermore, plasma spraying uses powder as an additional material having a particle size larger than about 10 micrometers. When obtaining nanometer or micron structures, this requires reducing the size of the basic particles. Furthermore, in order for the vector gas to eject particles into the plasma jet, the amount of particle motion must match that of the spraying gas or be at least slightly greater than the latter in order to allow the particles to penetrate well into the spraying gas. Therefore, when the mass of the particles decreases, good control of the particle size distribution and ejection parameters (gas flow rate, ejector diameter, and position of the ejector relative to the jet) is required so that the dispersion of the powder in the jet is limited to obtain an optimal spraying trajectory of the particles onto the target. Summary of the Invention Problems to be Solved by the Invention

[0011] In principle, conventional solutions do not allow for selective deposition by spraying each particle in a specific region of a component, especially with micron spatial resolution.

[0012] Furthermore, conventional solutions do not allow for depositing locally different materials on the target area, for example, in a manner that generates a multiphase coating. The term multiphase coating means a composite coating formed of at least two different materials or at least two material phases.

[0013] Furthermore, another problem that the present invention intends to improve relates to the difficulties associated with the deposition of particles from the nozzle. In fact, in order to obtain a high spatial resolution, it is necessary to control the nozzle part and the particle density.

[0014] Furthermore, the present invention aims to improve the drawbacks of the prior art by proposing an apparatus and a method that enable the deposition of particles of a material on a substrate and components with high precision in order to obtain a fine structure coating having excellent or improved adhesion characteristics without relying on the preparation of the surface of the substrate. In particular, the apparatus and method of the present invention enable the deposition of a wide range of materials in such a manner as to form a composite multiphase pattern based particularly on aggregates of individual particles.

Means for Solving the Problems

[0015] An apparatus for selectively depositing at least one particle on a deposition surface of a receiving substrate by shock wave-induced spraying is proposed, the apparatus comprising: - at least one laser light source configured to emit a laser beam, the laser beam being composed of a series of optical pulses, the laser light source; - a substrate carrier on which the substrate is fixed; - a shock wave generation layer having a first surface directed towards the laser beam and a second surface directed towards the deposition surface of the substrate; - an optical system for focusing the laser beam towards a focal region on the first surface of the generation layer; and comprising: - the second surface comprises a plurality of cavities, each of the cavities containing at least one particle; - the laser beam is configured to generate a plasma in a focal region on the first surface of the generation layer and a shock wave propagating from the first surface to the second surface within the generation layer to eject at least one particle in the direction of the deposition surface of the substrate.

[0016] The term "particle" in the meaning of the present disclosure means a metal particle, particularly a micron particle.

[0017] The term "micron particle" means a particle having a size between 1 μm and 100 μm including both ends.

[0018] Advantageously, the apparatus and method according to the present invention enable the use of a laser shock wave technique for depositing particles in a selective manner, particle by particle, on the surface of a substrate, and the construction in a target area of a three-dimensional component formed from the particles.

[0019] Thanks to the solution proposed in the present disclosure, it is no longer necessary to perform prior preparation of the surface of the substrate, such as sandblasting, in order to advantageously increase the surface roughness that acts on the mechanical adhesion of the particles. In other words, there is no longer a need to modify the state of the surface of the substrate in order to ensure the adhesion between the coating and the substrate. For this purpose, it is possible, for example, to create deposits of particles on fragile parts, in particular medical parts or jewelry parts.

[0020] Advantageously, the apparatus and method according to the present invention enable the creation of patterns on a micron scale on substrates or parts with complex shapes, or the local functionalization of target areas of the substrate.

[0021] By eliminating the use of a carrier gas and using only the shock wave generated by the plasma to spray the particles one by one onto the deposition surface of the substrate, the proposed technical solution avoids the technical constraints and problems linked to controlling the momentum of the particles and controlling the nozzle part as in the prior art, and enables deposition regardless of the nature of the surface of the substrate, the nature of the particles, the shape and geometry of the substrate.

[0022] Thanks to the deposition of the particles in a selective manner, one by one, it is possible to build 2D or 3D micron patterns on the target area of an existing metal part, or to obtain parts by the accumulation of particles on top of each other.

[0023] Thanks to the solution proposed by the present disclosure, it is also possible to handle the surface roughness of parts obtained by additive manufacturing. In fact, parts obtained by the additive manufacturing process generally have an arithmetic roughness of the outer shape (Ra) of several micrometers to several tens of micrometers. This roughness is related to the stacking of successive layers specific to the additive manufacturing process and also to the presence of powder particles agglomerated together on the surface of the part. Thanks to the method of the present invention, it is possible to deposit particles of the same nature as the material of the part, one by one, in the rough areas in order to reduce the surface roughness.

[0024] Thanks to the proposed solution, it is also possible to increase the density of the target area of the part in order to improve the fatigue characteristics of the part.

[0025] According to one embodiment of the present invention, the device further comprises a confinement layer that is transparent at the wavelength of the laser beam and covers the first face of the generation layer, the confinement layer being configured to confine the plasma generated at the level of the first face of the generation layer. This confinement layer is a layer of glass or a layer of water.

[0026] According to one embodiment of the present invention, the device further comprises a system for controlling the laser light source, configured to command the energy level of the laser beam.

[0027] According to one embodiment of the present invention, the control system comprises a computer configured to determine the optimal energy level of the laser beam based on a digital model as a function of the size of the particles, the material of the particles, the material of the receiving substrate, the material of the generation layer, and the thickness of the generation layer.

[0028] According to one embodiment of the present invention, the device further comprises heating means for heating the substrate.

[0029] According to one embodiment of the present invention, the device further comprises a temperature sensor configured to measure the temperature of the substrate.

[0030] According to another embodiment of the present invention, the device further comprises an image acquisition system such as a video camera.

[0031] The features disclosed in the following sections can be adopted optionally. The features can be adopted independently of each other or in combination with each other. - The confinement layer has a thickness between 200 μm and 5000 μm including both ends. - The shock wave generation layer has a thickness between 200 μm and 3000 μm including both ends. - The laser light source is configured to emit a laser beam composed of a series of optical pulses having a pulse duration between 1 nanosecond and 5 nanoseconds including both ends and an energy level between 1 joule and 10 joules including both ends. - Each cavity comprises at least two housings, each of the housings containing particles. - The particles have a diameter between 5 μm and 100 μm including both ends.

[0032] According to another aspect, the present invention is a method of depositing particles using the deposition device described above, the method comprising the following steps, namely, - In a first step (E1), generating a laser beam composed of a series of optical pulses; - In a second step (E2), directing the laser beam towards a first surface of the generation layer and focusing the laser beam at a level of a focal region on the first surface of the generation layer; - In a third step (E3), adjusting the energy level of the laser beam in such a manner as to generate plasma at a level of the first surface of the shock wave generation layer; - In a fourth step (E4), generating a shock wave in the generation layer, the shock wave propagating from the first surface towards a second surface of the generation layer and ejecting at least one particle in the direction of the deposition surface of the substrate. The present invention also proposes a method comprising these steps.

[0033] According to one embodiment of the present invention, the energy level of the laser beam is calculated based on a digital model as a function of the particle size, the particle material, the substrate material, the material of the generation layer, and the thickness of the generation layer.

[0034] According to another embodiment of the present invention, the method comprises the following steps, namely - Repeating steps E1 to E4 to deposit at least one particle on the calibration area of the deposition surface of the substrate; - Obtaining at least one image of the collision area of the particle on the deposition surface of the substrate; - Evaluating the plastic deformation of the particle and the collision area of the deposition surface of the substrate as a function of the energy level of the laser beam; - Determining the optimal energy level of the laser beam and further comprises a preliminary step (E0) of calibrating the energy level of the laser beam.

[0035] Other features, details, and advantages of the present invention will become apparent upon reading the following detailed description and analyzing the accompanying drawings.

Brief Description of the Drawings

[0036]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Best Mode for Carrying Out the Invention

[0037] The following figures and descriptions essentially include elements of a certain nature. Therefore, they not only better explain the present invention but also help to give its definition as necessary.

[0038] In FIG. 2, an apparatus 100 according to an embodiment of the present invention for selective deposition by laser shock wave-induced spraying is shown. According to this embodiment, the apparatus comprises a laser light source 101 configured to emit a laser beam 103 defined by the following parameters, namely, the wavelength, frequency, energy, diameter, and pulse duration of the laser. The parameters of the laser light source can preferably be set to adjust at least one of the parameters, particularly its energy level.

[0039] As an example, particularly in the example of using a particle deposition apparatus to deposit four particles at a speed of 500 m / s (FIG. 5), the train of laser pulses has a duration equal to 40 ns at a wavelength of 1064 nm. The laser beam is emitted with an energy of 10 J.

[0040] The apparatus also comprises a substrate carrier 130 to which a receiving substrate 140 intended to receive the particles sprayed by the apparatus is fixed. More precisely, the receiving substrate comprises a first free deposition surface 141 directed towards the laser beam and a second surface fixed to the support. The support is mounted on a movable plate that moves in a horizontal plane (X, Y) perpendicular to the direction of the laser beam in order to move the position of particle deposition. The support 130 can be directed in three directions to provide the deposition surface perpendicular to the laser beam in such a manner as to maximize the adhesion between the particles and the deposition surface. Furthermore, this type of support makes it possible to create complex patterns.

[0041] In the present disclosure, the deposition surface 141 corresponds to the surface of the substrate for the particles of the first layer or the surface of the layer deposited on the receiving substrate for the particles of the next layer.

[0042] The deposition apparatus 100 further includes an optical system 102 that enables adjustment of the focus along the axis Z perpendicular to the deposition surface.

[0043] The laser light source 101 and the optical system 102 are not described further, because they are known to those skilled in the art and may be the same as those of the prior art.

[0044] The deposition apparatus also includes at least one particle donor support 150.

[0045] As shown in FIG. 2, according to an embodiment of the present invention, the donor support 150 includes a plasma confinement layer 110 and a shock wave generation layer 120.

[0046] The confinement layer 110 has a first free surface 111 and a second surface 112 directed toward the laser beam. The shock wave generation layer 120 has a first surface 121 and a free second surface 122 having a contact interface with the second surface 112 of the confinement layer 110. The free second surface 122 includes a plurality of cavities 123, and each of the cavities is configured to accommodate particles 11.

[0047] In this way, the plasma confinement layer 110 and the shock wave generation layer 120 form the particle donor support 150 in the form of a stack.

[0048] The deposition apparatus also includes a second movable plate (not shown) to which the donor support 150 is removably attached, and the movable plate moves in horizontal planes X and Y perpendicular to the direction of the laser beam. Thus, thanks to the second movable plate, the position of the focus of the laser beam can be moved on the first surface 121 of the shock wave generation layer 120 in such a way that particles are selectively sprayed one by one onto the target area of the deposition surface 141 of the substrate 140. In this way, it becomes possible to select a specific particle 11 and spray the selected particle onto a specific area of the deposition surface.

[0049] According to one embodiment of the present invention, the deposition apparatus includes a system for commanding and controlling the movement of the receiving substrate 140 and the donor substrate 150 via a plate having micrometer accuracy and orientable with respect to six axes in order to generate complex shapes.

[0050] According to another embodiment of the present invention, the deposition apparatus includes a command and control system for each plate.

[0051] The confinement layer 110 is made of a material that is transparent at the wavelength of the laser beam. This layer may similarly be water in a container. The optical system 102 is configured to focus the laser beam 103 onto the first surface 121 of the shock wave generation layer through the confinement layer.

[0052] The function of this confinement layer 110 is to decelerate the expansion of the volume of the plasma generated at the interface 121 in such a way as to generate high pressure and thereby increase the pressure on the first surface of the shock wave generation layer 120. Furthermore, the presence of the confinement layer also makes it possible to increase the duration of the applied pressure. The confinement layer 110 preferably has a thickness between 200 μm and 5000 μm including both ends. The confinement layer is a dielectric layer. The confinement layer is preferably made of glass. The confinement layer can similarly be replaced with a film of distilled water or a transparent adhesive tape.

[0053] The shock wave generation layer 120 is made of a metal, for example aluminum, or a plastic material that is absorptive at the wavelength of the laser beam. The shock wave generation layer 120 has a thickness between 200 μm and 3000 μm including both ends. According to known physical phenomena, when a high-power photon pulse with a short duration is focused on the first surface 121 of the generation layer 120, when the laser beam penetrates into the thickness of the generation layer, the laser-material interaction is first reflected, and a region that absorbs laser energy is created. The penetration depth of the light wave in the solid is on the order of several nanometers. Because the pulse duration is very short and the beam power is high, the temperature rises very much in this region, and the very thin thickness of the material of the generation layer sublimates. Then the ionized vapor contacts the laser beam, generating a hot and dense plasma, and the plasma continues to absorb energy throughout the pulse duration.

[0054] Due to the expansion of the plasma generated at the level of the first surface of the generation layer, pressure is applied to the first surface of the generation layer. Due to the pressure on this surface, a compression wave is generated inside the thickness of the shock wave generation layer 120, resulting in a mechanical shock wave with an amplitude that can reach several tens of gigapascals propagating in the direction of the second surface 122. The shock wave produced in this way propagates locally from the first surface 121 of the generation layer to the second surface 122 of the generation layer. Due to the effect of the shock wave applying pressure to the particles contained in the cavity, the particles are sprayed in the direction of the deposition surface 141 of the receiving substrate 140.

[0055] The particles have a diameter between 5 μm and 100 μm including both ends. The substrate has a thickness between 500 μm and 2000 μm including both ends. The particles are deposited using a laser light source that enables the generation of a laser beam having a wavelength of 1064 nm and a pulse duration between 1 ns and 5 ns including both ends. The diameter of the laser beam at the focus is generally between 500 μm and 2000 μm including both ends. The energy of the laser beam is between 5 joules and 10 joules including both ends.

[0056] According to another embodiment of the present invention (not shown), the cavity can comprise a plurality of housings, each of which is sized to receive particles.

[0057] In an advantageous manner, the arrangement of the cavities on the free surface 122 of the shock wave generation layer directly forms the pattern that is desired to be reproduced on the deposition surface. Thus, when the particles are sprayed onto the deposition surface of the receiving substrate, the deposited particles directly form the required pattern. By spraying the particles in this way, it becomes possible to deposit them and at the same time transfer the pattern.

[0058] The cavities have a circular or elliptical cross-section, or a cross-section of other geometric shapes. The cavities can in particular be made by known laser texturing processes. The cavities produced in this way have micron dimensions of the same order of magnitude as the particles.

[0059] Thus, the device of the present invention makes it possible to use a laser shock wave to create a pattern on the deposition surface of a substrate by particle-by-particle deposition from a donor support.

[0060] The pattern can comprise a single layer formed from a plurality of particles. The pattern can likewise comprise a plurality of layers as illustrated in FIG. 2, each of the layers being formed from a plurality of particles.

[0061] According to one embodiment of the present invention, the selective deposition device comprises a frame for supporting a plurality of particle donor supports 150, each of the supports comprising one type of particle and one pattern. The frame is associated with a system of X, Y, Z axes. The various supports are fixed to the frame and are moved in the X and Y directions in such a way as to move the donor support in front of the deposition surface of the substrate.

[0062] FIG. 3 illustrates an example of a pattern 10 of particles forming an arrangement of particles on the deposition surface 141 of a substrate. According to this example, the pattern comprises four types of particles 11A, 11B, 11C, 11D arranged at a constant spacing L.

[0063] According to one embodiment of the present invention, as shown in FIG. 2, the directions of the laser beam 103 and the particle spray are directed in a direction opposite to gravity. In the configuration shown in FIG. 2, the free surface 122 of the shock wave generation layer 120 is directed upward in the direction of the deposition surface 141 of the substrate. During the spraying period, particles are ejected from the cavity containing the particles in an upward direction opposite to gravity. Therefore, with this configuration, the particles can be easily held in the cavity in the shock wave generation layer. In the situation where the confinement layer 110 is composed of water, the shock wave generation layer is immersed in water.

[0064] Determination of the Optimal Critical Velocity of Particles at the Moment of Particle Collision on the Substrate The adhesiveness of the particles to the substrate is a dominant factor in determining the performance of the coating.

[0065] In the meaning of the present disclosure, the term "adhesiveness" means the state in which the particles and the substrate are bonded.

[0066] The adhesiveness of the particles on the substrate is mainly governed by the critical velocity of particle collision.

[0067] In the meaning of the present disclosure, the term "critical velocity" means the velocity below which the particles do not adhere to the substrate.

[0068] Under optimal conditions, the collision velocity results in a shear force. Friction between two solid materials and the plastic deformation they undergo cause a local temperature rise in the materials. The collision region of the particles and the substrate undergoes plastic deformation that creates a bond between the particles and the substrate.

[0069] FIG. 4 schematically illustrates the plastic deformation received by the particle 11 and the collision region 142 of the substrate at the moment of particle collision on the substrate 140. The adhesiveness is reflected by the propulsion of the particles into the substrate and the formation of a hollow region 143 at the level of the collision region.

[0070] The behavior of fast-reaching particles at the moment of impact on the substrate was simulated by finite element calculation for the collision of a sphere onto a plane. Using known models, the collision of particles on the substrate was modeled by the Johnson-Cook type of behavior law. Based on this model, the phenomenon of plastic deformation of particles for the collision of particles on the substrate was simulated, and it is possible to calculate the optimal critical velocity for the adhesion of particles on the substrate as a function of parameters including the size of the particles, the material of the particles, and the material of the substrate.

[0071] Determination of the Ejection Velocity of Particles The optimal critical velocity that enables the adhesion of particles on the substrate is directly linked to the velocity at which particles are ejected from the cavity due to the effect of the shock wave. Therefore, the ejection velocity is linked to the shock wave generated by the laser beam in the shock wave generation layer.

[0072] According to known models, it is possible to model the propagation of the shock wave in the generation layer based on the Hugoniot's relation (the conservation law of the state in the medium), the Mie-Grüneisen equation of state, and the linear relational expression that links the velocity of the shock wave and the velocity of the material. Therefore, based on these equations, it has become possible to determine the velocity at which particles are ejected as a function of the amplitude of the shock wave induced by the laser beam, and thus the pressure applied by the plasma created by the laser beam. For this reason, it is then possible to determine the optimal energy level of the laser beam in order to obtain the optimal velocity for spraying particles as a function of the material of the generation layer and the thickness of the generation layer.

[0073] Therefore, due to the effect of the shock wave and the critical velocity of the particles at the moment of impact on the substrate, the velocity at which particles are sprayed varies as a function of the size of the particles, the material of the particles, the material of the substrate, the thickness and material of the shock wave generation layer, and the energy level of the laser beam.

[0074] To obtain good adhesion between the particles and the deposition surface of the substrate, knowing the particle size, the particle material, the material of the receiving substrate, the thickness and material of the generation layer, it is possible to adjust the energy level of the laser beam in order to obtain the critical kinetic energy of the particles at the moment of collision of the particles on the substrate.

[0075] Figure 5 illustrates an example of depositing four copper particles on an aluminum substrate using a laser shock wave.

[0076] The generation layer 110 is an aluminum layer having a thickness of 500 μm. The confinement layer is a glass layer and has a thickness of 5 mm. The free surface 122 of the generation layer contains four cavities each containing a copper particle.

[0077] The shock wave made it possible to spray the four particles onto the deposition surface. The velocity of the particles is 500 m / s, which is an empirical value.

[0078] A method according to an embodiment of the present invention for depositing particles by laser shock wave spraying on the deposition surface of a substrate will then be described in detail hereinafter with reference to FIG. 6.

[0079] In the first step (E1), the optimal energy level of the beam is calculated in the computer from a known numerical model. In this model, the particle size, the particle material, the material of the receiving substrate, the thickness of the receiving substrate, the thickness of the shock wave generation layer, and the material of the generation layer are known parameters. Therefore, in order to obtain good adhesion between the particles and the deposition surface of the substrate, it is possible to adjust the energy level of the laser beam in order to obtain the critical kinetic energy of the particles at the moment of collision of the particles on the substrate.

[0080] In the second step (E2), the control system of the laser source commands the laser source to emit a laser beam with the required parameters, namely, the energy level, wavelength, and pulse duration transmitted by the computer. The laser beam is focused on the first surface of the generation layer through the confinement layer. In the example illustrated in FIG. 5 of the present disclosure, the laser source operates, for example, with a wavelength of 1064 nm, a pulse duration of 5.1 ns, and an energy level of 1 joule.

[0081] In the third step (E3), plasma is generated on the surface of the interface between the confinement layer 110 and the shock wave generation layer 120. This is the result of the absorption of the energy of the laser beam by the generation layer. Plasma is created over an extremely short time period, typically a few nanoseconds, after the absorption of the laser beam.

[0082] In the fourth step (E4), a shock wave is generated in the generation layer and propagates in the direction of the free second surface 122 that carries the particles. This shock wave is the result of the pressure applied by the plasma on the surface of the generation layer. The shock wave reaching the free surface 122 causes the spraying of the particles accommodated in the cavity of the second surface 122 in the direction of the deposition surface 141 of the substrate 140.

[0083] According to an embodiment of the present invention, the method comprises a preliminary step (E0) of calibrating the critical velocity of the particles, where the critical velocity is the velocity of the particles at the moment of collision of the particles on the deposition surface of the substrate in order to obtain good adhesion between the particles and the substrate. Thus, this calibration step makes it possible to verify the numerical model in an experimental test of depositing particles using a laser shock wave on a test substrate. This calibration step can also be performed on a specific region of a substrate dedicated to calibration.

[0084] This preliminary calibration step consists of repeating steps E1 to E4 to deposit particles on the calibration region of the deposition surface of the substrate at different energy levels of the laser beam calculated based on the numerical model.

[0085] In this preliminary step, following step E4, the following steps are there. - Obtaining at least one image of the collision region of said particles on the deposition surface of the substrate, then - Evaluating the plastic deformation of the collision regions of the particles and of the deposition surface of the receiving substrate as a function of the energy level of the laser beam, - Determining the optimal energy level of the laser beam.

[0086] According to a first embodiment of the invention, the particle deposition apparatus comprises an image acquisition system such as a high-speed video camera, and its image acquisition frequency between 1000 Hz and 50000 Hz is synchronized with the pulse frequency of the laser source. By the image acquisition system, during the deposition procedure, real-time acquisition of at least one image of the state of the particles immediately after the collision of the particles on the deposition surface of the substrate as a function of the various energy levels of the calculated laser beam becomes possible.

[0087] Due to the three-dimensional characteristics of the state of the particles, qualitative control of the plastic deformation of the collision regions of the particles and of the deposition surface of the substrate, as well as evaluation of the quality of the adhesion between the particles and the substrate become possible. By the preliminary calibration step, determination of the optimal energy level of the laser beam to be subsequently used for depositing the particles for forming complex patterns or components becomes possible.

Industrial Applicability

[0088] The present invention can in particular find applications for making the following. - Jewelry having complex geometries - Medical components - Finishing coatings in the target area for reducing the surface roughness of parts obtained in particular by additive manufacturing - Coatings enabling modification of the physical properties of the area - Electrically functional coatings - Anti-corrosion coatings

[0089] As a non-limiting example, the particles may be made of the following. - Precious materials: gold, silver, platinum, or slightly precious materials - Ceramic materials - Standard metals

[0090] As a non-limiting example, the substrate may be made of the following. - Precious materials: gold, silver, platinum, or slightly precious materials - Metals - Composite materials - Ceramics

Description of reference numerals

[0091] 1 Thermal sprayer 2 Inlet 3 Inlet 4 Gas 5 Substrate 6 Surface 7 Particles 10 Pattern 11 Particles 11A Particles 11B Particles 11C Particles 11D Particles 100 Equipment, deposition equipment 101 Laser light source 102 Optical system 103 Laser beam 104 Plasma 105 Shock wave 110 Confinement layer, plasma confinement layer 111 First free surface 112 Second surface 120 Shock wave generation layer 121 First surface, interface 122 Second surface, free second surface, free surface 123 Cavity 130 Substrate carrier, support 140 Receiving substrate 141 Deposition surface, first free deposition surface 142 Collision region 143 Hollow region 150 Particle donor support, donor substrate 170 Control system 180 Heating means 181 Temperature sensor 200 Method

Claims

1. An apparatus (100) for selectively depositing at least one particle (11) by shock wave-induced spraying onto a deposition surface (141) of a receiving substrate (140), comprising: at least one laser source (101) configured to emit a laser beam (103), the laser beam being composed of a series of optical pulses; a substrate carrier (130) on which the substrate (140) is fixed; a shock wave generation layer (120) having a first surface (121) facing the laser beam and a second surface (122) facing the deposition surface (141) of the substrate; an optical system (102) for focusing the laser beam onto a focal region on the first surface (121) of the generation layer; and the second surface (122) comprises a plurality of cavities (123), each of the cavities accommodating at least one particle (11); the laser beam is configured to generate a plasma (104) in the focal region on the first surface (121) of the generation layer and a shock wave (105) propagating from the first surface (121) to the second surface (122) of the generation layer within the generation layer (120), so as to eject at least one particle (11) in the direction of the deposition surface (141) of the receiving substrate (140).

2. The deposition apparatus according to claim 1, further comprising a confinement layer (110) that is transparent at the wavelength of the laser beam and covers the first surface (121) of the generation layer, the confinement layer being configured to confine the plasma generated at the level of the first surface (121) of the generation layer (120).

3. The deposition apparatus according to claim 2, wherein the confinement layer is a glass layer or a water layer.

4. The deposition apparatus according to claim 2 or 3, wherein the confinement layer has a thickness between 200 μm and 5000 μm.

5. The deposition apparatus according to any one of claims 1 to 4, further comprising a system (170) for controlling the laser source configured to command the energy level of the laser beam.

6. The deposition apparatus according to claim 5, further comprising a computer configured to determine an optimal energy level of the laser beam based on a digital model as a function of the size of the particles, the material of the particles, the material of the receiving substrate, the material of the generation layer, and the thickness of the generation layer.

7. The deposition apparatus according to any one of claims 1 to 6, further comprising heating means (180) for heating the substrate (140).

8. The deposition apparatus according to any one of claims 1 to 7, further comprising a temperature sensor (181) configured to measure the temperature of the substrate.

9. The deposition apparatus according to any one of claims 1 to 8, further comprising an image acquisition system such as a video camera.

10. The deposition apparatus according to any one of claims 1 to 9, wherein the laser light source (101) is configured to emit a laser beam composed of a series of optical pulses having a pulse duration between 1 nanosecond and 5 nanoseconds and an energy level between 1 joule and 10 joules.

11. The deposition apparatus according to any one of claims 1 to 10, wherein each cavity (123) comprises at least two housings, and each of the housings contains particles.

12. The deposition apparatus according to any one of claims 1 to 11, wherein the particles have a diameter between 5 μm and 100 μm.

13. A method (200) of depositing particles using the deposition apparatus (100) according to any one of claims 1 to 12, comprising: In a first step (E1), generating a laser beam (103) composed of a series of optical pulses; In a second step (E2), directing the laser beam towards the first surface (121) of the generation layer (120) and focusing the laser beam at a level of a focal region on the first surface of the generation layer; In a third step (E3), adjusting the energy level of the laser beam in a manner such that plasma is generated at the level of the first surface of the shock wave generation layer by a system (170) for controlling the laser light source. In a fourth step (E4), generating a shock wave in the generation layer (120), the shock wave propagating from the first surface towards the second surface of the generation layer and ejecting at least one particle in the direction of the deposition surface (141) of the substrate (140). A method (200) comprising the above steps. **Claim 14** The deposition method according to claim 13, wherein the energy level of the laser beam is calculated by a computer based on a digital model as a function of the size of the particles, the material of the particles, the material of the receiving substrate, the material of the generation layer, and the thickness of the generation layer. **Claim 15** Repeating steps E1 to E4 to deposit at least one particle on a calibration region of the deposition surface of the substrate; Obtaining at least one image of a collision region of the particles on the deposition surface of the substrate by an image acquisition system such as a video camera; Evaluating the plastic deformation of the particles and the collision region of the deposition surface of the receiving substrate as a function of the energy level of the laser beam; Determining an optimal energy level of the laser beam The deposition method according to claim 13 or 14, further comprising a preliminary step (E0) of calibrating the energy level of the laser beam, including the above steps.

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