JP2018508644A - Thermal spraying method that integrates selective removal of particles - Google Patents

Abstract

The thermal spray system and method includes a hot gas generator with a nozzle that accelerates the heated gas toward the substrate in the form of a gas column protruding onto the substrate surface as a spot. One or more feed injectors proximate to the nozzle outlet directed to the gas column are connected to the feed source. The hot gas stream transfers heat and momentum to the feedstock, causing the feedstock particles to impinge on the substrate to form a coating. The system further includes one or more liquid injection devices proximate to the nozzle outlet that are directed toward the shaft and connected to a source of liquid. This system controls the flow and rate at which liquid is injected and allows control of the depth of penetration of the liquid into the gas column. This method selectively prevents sub-optimal feedstock particles from adhering to the substrate and allows sub-optimal deposits to be removed in situ.

Description

  The present invention provides a method for continuously reducing sub-optimal feedstock deposition during splashing and in situ removal of less adherent feedstock and surface treated grit particles and other debris from substrates and coatings. , Relating to integration into thermal spray systems.

  Referring to FIG. 1 of the drawings, conventional spraying is a coating in which a continuous flow of hot gas 1 generated in a chamber 2 is passed through a discharge nozzle 3 to form a divergent gas column 4 having an axis 5. Is the method. The column 4 is coaxial with the nozzle 3 and extends from the nozzle outlet to the substrate surface 6, where the gas column 4 projects into a surface spot 7. Due to the mixing of air into the edge of the gas column, the temperature in the gas column follows a Gaussian distribution 9 (FIG. 1), and the temperature decreases with the distance from the axis 5. Also, the mixing of air into the edge of the gas column reduces the gas velocity with distance from the shaft 5 according to a similar Gaussian distribution 9. The peak temperature (in the vicinity of the axis 5) in the sprayed gas column may reach a value exceeding 10,000 ° C. On the other hand, gas velocities may range from a few hundred meters per second to supersonic speeds. There are two main methods for heating the gas.

  1) Combustion chamber: A mixture of combustible gas and oxygen or air is ignited and released at supersonic (and subsonic) through a nozzle.

  2) Plasmatron: A plasmatron includes an arc chamber, and a mixture of gases is continuously fed through the chamber while simultaneously producing an electric arc between the cathode and anode. The gas mixture is heated by an electric arc and discharged through a nozzle as a high temperature, high velocity plasma stream. Delcea (Patent Document 1) shows one preferred plasmatron capable of emitting a high enthalpy (HE) plasma flow.

  Feedstock material is injected into the gas column via one or more injectors 10. The feedstock material becomes entrained in the gas column, the gas column transfers heat and momentum to the feedstock material, the feedstock material collides with the substrate surface at high speed, the feedstock material adheres to the substrate surface, A coating 11 is formed. Thermal spray coatings adhere to the substrate primarily by physical forces. Due to this fact, the substrate surface typically has been previously blasted with high speed abrasive particles prior to the coating process to increase surface roughness and provide a fixation point to which the coating can adhere. Processing is performed. In addition, particles that impinge on the substrate must be in an optimal temperature and velocity range to achieve a melting state and velocity sufficient to deform into a layered structure (commonly referred to as a splat) during impact. . The layered structure increases the ability to physically bond to the lower surface. In order to form an optimal thickness coating, more than one splat layer is usually required, in which case several overlapping passes are performed. The path generally consists of the gas column axis moving as indicated by arrow 8 relative to surface 6.

  In conventional thermal spraying, the feedstock material is typically a powder of various coating materials with a size of a few microns to a few tens of microns. The powder is injected into the hot gas column, typically using a carrier gas flow. The hot gas stream transfers heat and momentum to the powder, causing the powder to melt and impinge on the substrate surface to form a coating. Due to technical and economic constraints, the thermal spray powder has a relatively wide particle size, which is problematic. The reason is that the larger the particles, the greater the heat and momentum required to form splats between impacts compared to the smaller particles.

  In suspension spraying (STS), the feedstock material consists of particles suspended in a liquid medium. This suspension flow is used to inject the feedstock material into the hot gas column. Thus, the liquid medium replaces the carrier gas used in conventional thermal spraying. Compared to conventional spray powders, these particles are significantly smaller, generally in the submicron to nanomicron range. There are various solid particle sizes in suspension, but the range is generally smaller than that of conventional spray powders. Upon injection into the hot gas flow column, the liquid solvent in the suspension is evaporated by the heat of the gas column. Thereafter, heat and momentum are subsequently transferred to the particles, which are melted and impinged on the substrate surface to form a coating.

  The particle size variations seen in conventional powder and suspension feeds are detrimental to the spraying process. Ideally, all feed particles should be entrained and moved in the hottest and fastest core region of the gas column along axis 5. However, this injection method (whether carrier gas or liquid medium) typically gives approximately the same rate for all feed particles. As a result, as shown in FIG. 1 of the drawings, only the feedstock particles 12 of the optimal size for the injection conditions and gas column conditions remain near the axis 5 of the gas column 4, thereby providing the feedstock particles 12 as It will be struck with the substrate at the temperature and speed necessary to obtain a high quality coating. The largest and heaviest particles 13 travel farther into the gas column 4 and travel outside the core region in the cooler, lower velocity region of the gas column 4 opposite the feedstock injector 10. Tend to. In the cooler, lower speed region, the particles 13 do not receive sufficient heat and momentum to form splats when impacting the substrate. As such, they do not adhere well to the substrate and form a sub-optimal deposit in an annular area surrounding the central area of the high quality coating. Similarly, the smallest and lightest feedstock particles 14 form a sub-optimal deposit in an annular region surrounding the central region of the high quality coating. The reason is that these particles cannot enter the core of the gas column and instead move on the edge where the temperature and velocity are suboptimal. Because the coating is typically made by overlapping passes to create multiple deposition layers, sub-optimal deposits can be trapped in the coating, reducing the adhesion and integrity of the coating. As a result, coating strength is improved by reducing sub-optimal deposit formation or confinement in the coating. Sub-optimal deposit formation can be reduced by increasing the proportion of optimally sized particles in the feedstock, however, reducing the particle size range significantly increases the total cost of the coating process. Tend. Alternatively, undesirable sub-optimal deposit confinement can be reduced by clean off these deposits during the coating pass.

  A commonly used technique for removing unwanted material from a surface before applying a thermal spray coating involves directing a jet of pressurized gas to the surface. In many cases, the compressed jet alone cannot be removed sufficiently, so solid particles such as dry ice or abrasive ceramic grit are added to the jet for more aggressive removal. In the case of abrasive grit blasting, it is generally necessary that the coated area adjacent to the area to be removed is obscured or shielded from the grit to prevent damage to the coating. In addition, the grit blasting process leaves dust particles on the surface, which can be trapped in the coating and can reduce the adhesion and integrity of the coating. These blasting techniques use a separate device from that required for spray coating application. As a result, capital expenditure, repair management costs, and additional expense for coating production time are incurred if the thermal spray process is interrupted while the blasting device is removing unwanted material.

  It may be argued that the feedstock injection can be stopped and a hot gas column can be used to remove sub-optimal deposits from the surface without the need for a separate device. This approach is not feasible. The reason is that the heat from the gas can partially or completely melt the sub-optimal deposit, which increases the adhesion of the sub-optimal material after it has cooled. To bring. Furthermore, even though the sub-optimal deposit adhesion is increased by the hot gas column, the physical bonding and surface finish as a result of this melting and cooling process is not comparable to that caused by the high velocity impact of the molten particles.

  De Vries et al. (US Pat. No. 5,637,086) teaches atomic layer deposition techniques. In order to deposit a coating having the same chemical properties as the feedstock, the feedstock is not injected into the plasma. Rather, a mixture of reactive gases is supplied to the reaction chamber and a plasma is introduced separately to increase the reaction rate. Ions from the gas are chemically bonded to the substrate to form an atomic layer. Water vapor is then periodically injected along the substrate surface as a reactive agent that binds to the surface by either additional or displacement methods to change the surface chemistry. In this way, De Vries et al., Using more reactive species to randomly break existing chemical bonds of undesired atoms / molecules on the surface, the result is that more reactive species are undesirable. It teaches replacing atoms / molecules and changing surface chemistry. The technique of De Vries et al. Is not transferable to a thermal spray process where bonding occurs by physical forces instead of chemical forces. For example, if for some unknown reason it might be considered to inject water vapor along the substrate surface while spraying the coating as taught by De Vries et al. There is a high probability that the raw material particles will not be cooled to a degree sufficient to prevent adhesion, and there is a high possibility that sub-optimal deposits with a low water vapor velocity cannot be removed. Therefore, the present inventors believe that it is not natural to do such a thing.

  Ma et al. (US Pat. No. 6,057,096) teaches a thermal spray system that uses a combustion chamber and a nozzle for emitting a plume toward the substrate. A feedstock consisting of a liquid medium, which may include a mixture of organic / inorganic metal salts or a suspension of small sized solid particles in water or volatile solvents, is injected into the plume. Water and solid particles are premixed as a single feed and fed to the plume as a mixture from the same reservoir. A suspension containing water is used by Ma et al. As a carrier for solid particles, simply because it is difficult to supply fine particles (less than 10 micrometers in size) that use gas as a carrier. Yes (paragraph 0007). Ma et al. Do not teach the injection of a liquid, such as water, separated from solid particles in the plume into the plume, and the conditions for achieving such separation are also disclosed in the description of the embodiments. Absent. Furthermore, Ma et al. Do not teach liquid injection to modify the deposition characteristics or structure of the coating that is formed.

  Kawaguchi et al. (US Pat. No. 6,057,049) teaches that semiconductor wafer manufacturing can result in residues that release gaseous reactants (“outgas”) when exposed to atmospheric gases and water vapor. These reactants can cause contamination or corrosion problems to the parts or processing equipment (paragraph 0206). To solve this problem, Kawaguchi et al. Describe preheating a wafer containing residue using an apparatus that generates a static, low-temperature glow discharge plasma confined in a vacuum chamber. (Paragraph 0031). At this time, depending on the chemical nature of the residue, the wafer is exposed to an oxygen-containing gas or a hydrogen-containing gas, either of which can be water vapor (paragraph 0029). This exposure releases problematic reactants and turns them into non-corrosive, volatile species that are then removed from the vacuum chamber by venting the gas (paragraph 0030). Residue removal taught by Kawaguchi et al. Is essentially a highly reactive heat treatment that is performed statically under vacuum conditions and designed to turn undesirable material into a gas. This process is unique to chemistry and interest in the semiconductor industry. Such a removal mechanism is a thermal transfer performed in an atmosphere containing relatively non-reactive, chemically unbound debris that is best removed by mechanical transposition, ie, collisions between particles and debris. Does not apply to the process.

  Schliinger et al. (US Pat. No. 6,057,096) teaches the use of a plasma torch not to spray a heat applied coating, but rather to heat the garbage and compress it into a turntable located at the bottom of the incinerator chamber. doing. After compression and incineration, the treated waste is removed from the chamber and emptied, and the process is resumed. The torch is attached through the upper lid of the incinerator with the plasma plume directed on the turntable. The waste to be treated may be solid as well as liquid. Solid and liquid debris are not injected into the plasma plume, both of which are fed through a single tube located remote from the plasma plume (part 22 of the drawing and third column lines 6-7). Schliinger et al. Teach feeding solid and liquid materials into a plasma generated by a plasma torch, but the purpose of the process is to destroy the feedstock. Thus, Schliinger et al. Does not provide any conditions that are clearly available in a thermal spray coating process that seeks to maintain the maximum desired feedstock. Furthermore, Schliinger does not provide any conditions for the liquid to be directly injected into the plasma plume in order to influence the way the feedstock particles are processed in the plume.

  Rosenflanz et al. (US Pat. No. 5,637,086) teaches the use of a plasma torch to process feedstock materials for the purpose of producing amorphous or glass materials. Various ceramic particle feeds are suspended in the carrier gas to be fed into the plasma plume. When fed into a plasma plume of a predetermined length, the feedstock particles are heated and melted into droplets. Rosenflanz et al. Do not provide for injecting liquid into the plasma plume as well. Instead, Rosenflanz et al. Teach spraying plume and feedstock material into the liquid to cool the molten feedstock into particles in the form of spheres or balls, and this process is coating manufacturing (Paragraph 0104).

US Pat. No. 6,114,649 US Patent Application Publication No. 2009 / 0324971A1 US Patent Application Publication No. 2008/0072790 US Patent Application Publication No. 2004/0203251 U.S. Pat. No. 4,770,109 US Patent Application Publication No. 2007 / 0084244A1

  Neither the above-mentioned techniques nor the prior art make it possible to reduce the deposition of sub-optimal feedstock particles during spattering while removing surface debris in-situ in a controlled manner during the spray coating process. It would therefore be desirable to provide both of these means to avoid confinement of particles having sub-optimal properties in the coating.

  The present invention is intended to continuously reduce sub-optimal feedstock deposition during splatter and to remove debris such as less adherent feedstock and surface treated grit particles in situ from substrates and coatings. It relates to integrating the method into a thermal spray system.

  In one aspect of the invention, an integrated method is used to form a coating on the substrate surface. The method includes providing a source of heated gas and a nozzle for shaping the heated gas into a gas flow column coaxial with itself, the column protruding into a spot on the substrate surface, and supply Providing one or more infusion devices used to inject the raw material into the gas flow column and used to inject the liquid into the gas flow column; Defining a portion of the raw material profile as optimal and defining the remainder as sub-optimal, a first region arranged to wrap around a column axis, and surrounding the first region and first Defining two volume regions within the gas flow column, including a second region that is coaxial with the region, wherein the first region projects into a spot on the substrate surface and the second region projects into an annular ring on the substrate surface. The annular ring is A step that is coaxial with the pot and encloses the spot, and injects the feed into the gas stream column, the optimal feed is entrained in the first region of the stream, while the sub-optimal feed is in the second of the stream Adjusting the injection parameters to control the depth of feed penetration into the gas flow column to be entrained in the region; and injecting liquid into the gas flow column; Adjusting the injection parameters to control the depth of liquid penetration into the gas flow column to be entrained in the two zones, wherein the liquid is entrained in the second zone of the flow Reducing the temperature of the sub-optimal portion of the substrate, the temperature decrease being sufficient to suppress or prevent the sub-optimal feedstock from adhering to the substrate surface, injecting the liquid into the gas flow column, Entrained in the second region of the flow, and the liquid hits the substrate Adjusting the injection parameters to control the depth of liquid penetration into the gas flow column to remove debris on the substrate or embedded in the substrate, and a first region of the gas flow column Forming a coating on the substrate surface by substantially depositing the feedstock from within the spots projected to the surface by the coating, the coating thus being from the feedstock deposited at optimum temperature and speed conditions. Comprising substantially configuring steps.

  In another aspect of the present invention, a thermal spray apparatus adapted to form a coating on a substrate surface includes a source of heated gas and a nozzle for shaping the heated gas into a gas flow column coaxial with itself. A nozzle adapted to project into a spot on the substrate surface, and a plurality of injectors, the plurality of injectors positioned to inject the feedstock into the gas flow column And at least one injection device positioned to inject liquid into the gas flow column, the injection device being configured to establish a feedstock profile, the first part of the feedstock profile being optimal and the remainder Is sub-optimal, and the first part and the rest include a first region arranged to wrap around the axis of the column and a second region surrounding the first region and coaxial with the first region. Defining two volume regions in the gas flow column, the first region protruding into a spot on the substrate surface, the second region protruding into an annular ring on the substrate surface, the annular ring being coaxial with the spot and surrounding the spot; A plurality of injectors, a controller and a valve for injecting a feedstock into the gas flow column, wherein the optimum feedstock is entrained in the first region of the stream, while the suboptimal feedstock is A controller and a valve connected to at least one of the injection devices to adjust the injection parameters to control the depth of feed penetration into the gas flow column to be entrained in the two zones Including. The controller and valve control the depth of liquid entry into the gas flow column to inject liquid into the gas flow column and so that the liquid is substantially entrained in the second region of the flow. In order to adjust the injection parameters, the liquid is connected to at least one of the injection devices and the liquid reduces the temperature of the sub-optimal part of the feed entrained in the second region of the flow, It is sufficient to suppress or prevent the sub-optimal feedstock from sticking to the substrate surface.

  In a lower form, the controller and valve of the apparatus are adapted to form a coating on the substrate surface by depositing a feedstock substantially from within a spot projected to the surface by the first region of the gas flow column. Constructed, the coating consists essentially of feedstock deposited at optimum temperature and speed conditions.

  These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings.

FIG. 2 is a side view (1) and an end view (1a) showing a schematic representation of a conventional thermal spray process that provides a hot gas column extending from a nozzle to a substrate surface. The coating is deposited in spots on the substrate surface that are provided on the substrate surface with protruding gas columns. It is the side view (2) and end view (2a) which show one step in preferable embodiment of the thermal spraying method. Two coaxial volume regions are defined in the gas column, with the hotter and faster first region 15 surrounding the gas column axis 5 and the cooler and slower second region 16 wound around the region 15. The It is a graph which shows the relationship between particle size and number. FIG. 3 is a side view (3) and an end view (3a) showing one step in a preferred embodiment of the thermal spray system and method. Feedstock is injected via an injector 19, with optimal feedstock particles being entrained in region 15 and suboptimal particles being entrained in the upper portion of region 16. Also shown is a liquid injection device 21 that is used to inject liquid so that the liquid becomes substantially entrained in the upper portion of the second region 16. FIG. 4 is a side view (4) and an end view (4a) illustrating another step in a preferred embodiment of the thermal spray system and method. Feedstock is injected through an injector 19, with optimal particles entrained in region 15 and sub-optimal particles entrained in the upper and lower portions of region 16. Two opposing liquid injection devices 21, 31 are also shown. The injection device is used to inject the liquid so that it is substantially entrained in the upper and lower portions of region 16 respectively. FIG. 6 is a side view (5) and an end view (5a) illustrating another step in a preferred embodiment of the thermal spray system and method. Feedstock is injected through the opposing injectors 19, 25, with optimal particles entrained in region 15 and sub-optimal particles entrained in the upper and lower portions of region 16. Two opposing liquid injection devices 21 and 31 are likewise shown. These injection devices are used to inject liquid so that the liquid becomes substantially entrained in the upper and lower portions of region 16. 3 is a schematic front view of a nozzle 3. FIG. A plurality of feedstock injection devices 19, 25 and a plurality of liquid injection devices 21, 31 are arranged around the shaft 5. FIG. 6 is a side view (7) and an end view (7a) showing a preferred embodiment of the method. A coating is deposited and the substrate surface is cleaned by alternating steps of the method described in the present invention.

  Thermal spraying apparatus / systems and methods are used to continuously reduce sub-optimal feedstock deposition during splattering, and on-site substrate and coating debris such as less adherent feedstock and surface treated grit particles. Provided to be removed from. The apparatus (FIG. 2) includes a hot gas generator 2 and a nozzle 3 that are used to generate hot gas columns 4 that project into spots on the substrate surface 6. In an exemplary embodiment of the invention, the hot gas column characteristics, coating performance requirements, and feedstock characteristics combine to define the optimal feedstock size range. Thus, any particle size outside this range is classified as sub-optimal or undesirable. As mentioned above, a feed size distribution consisting only of particles within optimal dimensions is unrealistic. In practice, the most efficient scenario is to concentrate the feedstock particle size distribution within an optimal size range, as shown schematically in FIG. 2b. Thus, in the gas column 4, the location of the feedstock particles from each section defines two volume regions, region 15 and region 16.

  Region 15 surrounds axis 5 and protrudes into a central spot 17 on substrate surface 6. This region is characterized by the location of the optimal feedstock particles, meaning that the particle temperature and velocity conditions that occur in region 15 result in an optimal coating on surface 6.

  The region 16 protrudes into an annular region 18 surrounding the region 15 and surrounding the central spot 17 on the substrate surface 6. Region 16 is characterized by the location of sub-optimal feedstock particles, so the particle temperature and velocity conditions that occur in region 16 are insufficient to produce an optimal coating on surface 6. As a result, region 18 is formed by suboptimal particle deposition.

  FIG. 3 shows an embodiment in which the system includes a first injection device 19 for injecting feedstock 20 into the gas column and a second injection device 21 for injecting liquid 22 into the gas column, The second injection device is shown positioned downstream of the first injection device and adjacent to the first injection device. For this embodiment, the feedstock particle size distribution is distorted and consists only of particles within the optimal size range. As a result, the size of the injector 19 and the rate of feedstock injection will result in optimal feedstock 23 entry into the region 15. On the other hand, sub-optimal feedstock particles 25 are limited to the top of region 16. Optimal feed particles 23 entrained in region 15 are transferred from the hot gas stream sufficient heat and momentum to impact the substrate surface 6 and form an optimal quality coating 24 limited to spots 17. . Suboptimal feed particles 25 entrained in the upper part of region 16 are cooled by liquid 22, which is mainly entrained in the upper part of region 16 by adjusting the size of device 21 and the rate of liquid injection. . As shown in FIG. 3, the cooling caused by the liquid 22 can reduce the extent to which the sub-optimal feed particles melt to the point where splat formation is prevented, and the cooled sub-optimal feed particles 27 are on the surface. 6 so that it does not adhere and rebounds without forming a coating. Thus, the liquid 22 and cooled sub-optimal feedstock particles 27 can impact the surface 6 and can function as a polishing medium, with surface debris 26 being faster than the movement of the spot 17 and the formation of the coating 24. The weakly attached feedstock and grit particles represented by are removed. Furthermore, the liquid 22 acting as an abrasive medium at the surface 6 and the cooled sub-optimal feedstock particles 27 can remove surface debris embedded with grit particles 28 and the like, removing them from the surface and Avoid being trapped in the coating. Furthermore, heating by the hot gas stream and cooling by the impinging liquid assist in the expansion and contraction of the surface 6 and the weakly attached / embedded debris particles 26, 28, respectively, from the surface of the debris particles. It can be caused in such a way. If an enhanced abrasive process is desired, the liquid 22 may contain a suspension of abrasive particulates such as silicon or aluminum oxide. Particulates are entrained at the top of region 16 where they are accelerated towards surface 6 without achieving the speed or degree of melting necessary to adhere to surface 6 upon impact. These particulates thus enhance the removal of debris 26,28.

  FIG. 4 shows an embodiment where the feedstock particle size distribution is Gaussian and contains particles below and above the optimal size range. In this case, larger than optimal particles 29 injected in the feed stream 20 will pass through the region 15 and be entrained in the lower part of the region 16. Since these particles 29 do not receive sufficient heat and momentum in the region 16, they form a sub-optimal deposit represented by the surface debris 30, after the movement of the spot 17 and the formation of the coating 24. Chasing. As discussed above with reference to FIG. 3, feed particles 25 smaller than optimal do not have sufficient momentum to enter region 15. As a result, the sub-optimal feed particles 25 are entrained in the region 16 that does not receive sufficient heat and momentum to form the optimal coating 24 when impinging on the surface 6, so that instead, a sub-optimal Feedstock particles 25 join the surface debris 26. The negative situation associated with surface debris 26, 30 is solved by incorporating opposing liquid injection devices 21, 31 as shown in the preferred embodiment of FIG. The size of the injection device 31 and the speed of injection are adjusted so that entrainment of the liquid 32 occurs substantially in the lower part of the region 16. Some of the particles 29 are then cooled by the liquid 32 and melted to a degree insufficient to adhere to the substrate and impinge on the substrate, and these cooled sub-optimal feedstock particles 33 are present on the surface 6. It does not adhere to the surface and rebounds without forming a coating. Thus, the liquid 32 and suboptimal feedstock particles 33 can strike the surface 6 and function as an abrasive medium, following the movement of the spot 17 and the formation of the coating 24 in the region 18 region. The weakly attached surface debris 30 is removed. This removal mechanism can also remove embedded debris such as grit particles 34 from the surface 6. Furthermore, heating by the hot gas stream and cooling by the impinging liquid assist in the expansion and contraction of the surface 6 and the weakly attached / embedded debris particles 30, 34, respectively, to remove those debris particles from the surface. It can also be caused by such a method.

  With respect to the upper portion of region 16, the mechanism of movement is the same as described above with reference to FIG. The sub-optimal cooling of the feedstock particles 25 in the region 16 by the liquid 22 reduces adhesion to the surface 6 in the event of a collision. As shown in FIG. 4, several cooled sub-optimal feed particles 27 hit the surface 6 and bounce back without any adhesion. Thus, the liquid 22 and suboptimal feedstock particles 27 can impact the surface 6 and can function as an abrasive medium and are represented by the surface debris 26 earlier than the movement of the spot 17 and the formation of the coating 24. Remove weakly attached feedstock and grit particles. Furthermore, the liquid 22 and suboptimal feedstock particles 27 that act as polishing media at the surface 6 can remove embedded surface debris, such as grit particles 28, and remove them from the surface while they are trapped in the coating. To be prevented. Furthermore, heating by the hot gas stream and cooling by the impinging liquid assist in the expansion and contraction of the surface 6 and the weakly attached / embedded debris particles 26, 28, respectively, from the surface of the debris particles. It can be caused in such a way.

  Multiple feedstock injectors can be distributed around the gas flow axis 5 if more feedstock is required to be injected for increased power. FIG. 5 of the drawings represents another preferred embodiment of the system shown in FIG. 4 with an additional feedstock injector 35 located on the opposite side of the feedstock injector 19. The mechanism for injection and removal of sub-optimal particles and surface debris is the mirror of the mechanism described for the embodiment shown in FIGS.

  In another embodiment of the present invention, FIG. 6 of the drawings shows the nozzle 3 with a plurality of feedstock injectors 19, 35 and a plurality of liquid injectors 21, 31 arranged around the shaft 5. A schematic front view is shown.

  Another preferred embodiment of a thermal spray system incorporating the present invention is shown schematically in FIG. 7 of the drawings. A gas flow column is shown extending from the nozzle 3 to the substrate surface 6, the column having a defined core region 15 surrounding the axis 5. The feedstock injector 19 is shown having a flow control valve 37. Similarly, the liquid injection device 21 is shown having a flow control valve 38. One of each infusion device is shown in FIG. However, it is possible to incorporate only one infusion device connected to both control valves 37, 38, or a plurality of arrangements arranged around the shaft 5 as explained above with reference to FIG. An injection device may be used. For the embodiment shown in FIG. 7, in a first step, the thermal spray system moves parallel to the arrow 8 relative to the surface 6, so that one or more layers of coating 11 or 24, FIG. Or deposited by the method described above with reference to 5. In the second step, the feed flow is stopped by valve 37 and the liquid velocity is adjusted by valve 38 so that the liquid is substantially entrained within the region 15 of the gas flow. In the third step, the spray system moves in the direction of arrow 8 and / or arrow 39 with respect to the surface 6 and, according to the method described above with reference to FIG. 28 is removed from surface 6 and coating 11 or 24. In the fourth step, the control valve 37 is opened and the feedstock and liquid flow are processed as described above with reference to FIG. 1, 3, 4 or 5 for one or more coatings 11 or 24. Adjusted to deposit.

  It will be understood that variations and modifications can be made to the structure described above without departing from the inventive concepts. It is further understood that such concepts are intended to be covered by the following claims, unless the claims explicitly indicate otherwise in those languages.

  Embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

Claims (14)

An integrated method used to form a coating on a substrate surface,
Providing a source of heated gas and a nozzle for shaping the heated gas into a gas flow column coaxial with itself, wherein the column protrudes into a spot on the substrate surface; Providing one or more injection devices used to inject the gas flow column and to inject liquid into the gas flow column;
Establishing a feedstock profile, defining a portion of the feedstock profile as optimal and determining the remainder as suboptimal;
Two volume regions including one first region arranged to wrap around the axis of the column and a second region surrounding the first region and coaxial with the first region are divided into the gas flow The first region projects into a spot on the substrate surface, the second region projects into an annular ring on the substrate surface, the annular ring is coaxial with the spot and Enclose, step,
A feedstock is injected into the gas flow column so that the optimum feedstock is entrained in the first region of the stream while the suboptimal feedstock is entrained in the second region of the stream. Adjusting the injection parameters to control the depth of feedstock entry into the gas flow column;
Injecting liquid into the gas flow column and controlling the depth of liquid penetration into the gas flow column such that the liquid is substantially entrained in the second region of the flow Adjusting a parameter, wherein the liquid lowers the temperature of the sub-optimal portion of the feedstock entrained in the second region of the stream, the temperature drop being reduced by the suboptimal feedstock. Steps sufficient to suppress or prevent adhesion to the substrate surface;
Liquid is injected into the gas flow column, the liquid is substantially entrained in the second region of the flow, and the liquid hits the substrate and is embedded in debris on the substrate or in the substrate. Adjusting the injection parameter to control the depth of the liquid entry into the gas flow column to remove debris;
Forming a coating on the substrate surface by depositing a feedstock material substantially from within the spot projected to the surface by the first region of the gas flow column, the coating thus comprising: An integrated method used to form a coating on a substrate surface comprising the step of substantially consisting of a feedstock deposited at optimum temperature and rate conditions. Stopping the feedstock flow;
Adjusting the pressure and velocity of the liquid entering the first region of the gas flow column;
The method of claim 1, further comprising moving the pillar across one or both of the coating and a surface adjacent to the coating for the purpose of removing debris.   The method of claim 1 or 2, wherein the source of heated gas is a combustion chamber.   The method according to claim 1, wherein the source of the heated gas is a plasmatron.   The method of claim 1 or 2, wherein the feedstock is in the form of a powder.   The method of claim 1 or 2, wherein the feedstock is a slurry comprising a liquid containing suspended particulates of a coating material.   The method of claim 3, wherein the feedstock is in powder form.   The method of claim 3, wherein the feedstock is in the form of a slurry comprising a liquid containing suspended particulates of a coating material.   The method of claim 4, wherein the feedstock is in powder form.   The method of claim 4, wherein the feedstock is in the form of a slurry comprising a liquid containing suspended particulates of a coating material.   The method according to claim 1, wherein the liquid is water.   The method according to claim 1, wherein the liquid contains suspended abrasive particles, and the conditions are adjusted so as not to cause adhesion of the abrasive particles. A thermal spraying device used to form a coating on a substrate surface,
A source of heated gas;
A nozzle for shaping a heated gas into a gas flow column coaxial with itself, the column adapted to project into a spot on the substrate surface;
A plurality of injection devices, wherein the plurality of injection devices are positioned to inject at least one injection device into the gas flow column, and to inject liquid into the gas flow column; At least one injection device configured to establish a feedstock profile, wherein the first portion of the feedstock profile is optimal and the remainder is suboptimal, the first portion and the The remainder includes a first region arranged to wrap around the axis of the column, and a second region surrounding the first region and coaxial with the first region. One volume region is defined, the first region projects into a spot on the substrate surface, the second region projects into an annular spot on the substrate surface, the annular spot is coaxial with the spot and the Surrounding the pot, and a plurality of injection devices,
A controller and valve for injecting the feed into the gas flow column and adjusting the injection parameters to control the depth of feed entry into the gas flow column; A controller and a valve connected to at least one of the
The controller and valve also provide liquid to the gas flow column for injecting liquid into the gas flow column and so that the liquid is substantially entrained in the second region of the flow. To adjust the injection parameters to control the depth of penetration, the liquid is connected to at least one of the injection devices and the liquid is entrained in the second region of the stream. Reducing the temperature of the sub-optimal part, the temperature drop being sufficient to suppress or prevent adhesion of the sub-optimal feed to the substrate surface;
Thereby, the apparatus can form a coating on the substrate surface by substantially depositing the feedstock from within the spot protruding from the surface by the first region of the gas flow column. A thermal spray apparatus used to form a coating on a substrate surface, wherein the coating consists essentially of a feedstock deposited at optimum temperature and speed conditions.   The controller and valve are programmed such that the optimal feed is entrained in the first region of the stream while the sub-optimal feed is entrained in the second region of the stream. The thermal spraying device according to claim 13.

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