JP3524871B2 - High-speed thermal spray apparatus for forming a substance and a method for forming a coating or a bulk substance by the spray apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame spray device for depositing coating and bulk material by a thermal spray method and a flame spray method for forming a coating or a bulk material by the spray device. In particular, the present invention relates to high speed oxidant-fuel spray devices and methods that spray non-melting particles at a particle velocity approximately equal to the gas jet velocity to provide low oxidation, high density coatings and agglomerates. It relates to a high-velocity flame spray device suitable for forming substances and a method for forming coatings or bulk substances by means of this spray device.

[0002]

BACKGROUND OF THE INVENTION Generally, flame spray devices and methods for depositing coatings and agglomerates by a thermal spray technique rely on a fast oxidant gas-fuel spray, but when the oxidant gas is oxygen, that technique. Is known as high velocity oxygen-fuel (HVOF) spray. Similarly, if the oxidant gas is air or oxygen-enriched air, then high velocity air-fuel (H
It is known as VAF) spray.

This thermal spray has been used extensively to form metals and ceramics in the form of coatings or agglomerates on various substrates. Most thermal spray techniques use the energy of a hot gas jet to heat and accelerate particles of the spray material and impinge the particles on a substrate to form a coating.

[0004] Generally, high velocity oxygen-fuel (HVOF) systems combust fuel and oxygen in an inner burner under elevated pressure, usually a few bar, to produce a jet of hot gas. The fuel is a gas such as propane, methane, propylene, MAPP gas, hydrogen, or a liquid such as kerosene. Combustion gases expand from the burner into the exhaust nozzle or barrel to reach the speed of sound. In addition, expansion into the atmosphere or into a divergent nozzle section such as a Laval nozzle produces a supersonic jet. For this reason, this technique is called high speed.

The first aforesaid device is James A.
Invented by James A Browning (U.S. Pat. Nos. 4,342,551 and 4,343,605, issued August 1982). Many improvements to the HVOF gun were aimed at heating and accelerating the spray material with better efficiency (US Pat. No. 4,37).
0, 538, 4, 416, 421, 4, 540, 121, 4,5
68, 019, 4, 634, 611, 4, 836, 447, 5,
019, 686, 5, 206, 059, 5, 535, 590). Although this HVOF means forms a relatively high density coating, upon melting the particles, at least in part, a relatively high oxide containing material is deposited, significantly activating the surface of the particles. Due to incomplete combustion and ejection of air from the atmosphere, the jet always contains gaseous oxygen, so the molten surface of the particles is rapidly oxidized. Moreover, these means are quite expensive as they consume large amounts of compressed oxygen. Finally, melted spray particles can clog long nozzles, causing many problems in the operation of HVOF devices.

A high speed air-fuel (HVAF) device was first conceived as an inexpensive alternative to the HVOF means (US Pat. No. 5,120,582). The main mode of operation of this device is the combustion of air and kerosene. In addition, US Patent No.
Design improvements were made in 5,405,085 and 5,520,334. The main problem with this device is that the flame propagation velocity of the fuel-air mixture is two orders of magnitude slower than that of the fuel-oxygen mixture,
If the gas flow velocity is high, combustion becomes unstable.
With a relatively long internal burner, combustion is stable and complete. However, this makes it impossible to introduce the spray powder into the axial center positions of the burner chamber and the nozzle. That is, if the burner chamber is too long, the spray particles cannot pass through the burner chamber. When particles are jetted to the nozzle side wall instead of jetting at the axial center position,
Nozzle clogging occurs, causing a greater problem than the HVOF device that uses injection at the axial center position. The use of hydrogen or methane for ignition of combustion and as a pilot flame is neither practical nor safe for many HVAF guns.

Vladimir Berashchenko, one of the inventors of the present invention (US Pat. No. 5,932,293)
mir Belashchenko) and Viatcheslav Baranovski introduced a significant improvement in the HVAF design: a permeable burner block in the internal burner chamber. When the air-fuel mixture is heated above the autoignition temperature, the hot walls and passages of the permeable burner block continuously burn the mixture, thus stabilizing the combustion even with relatively small burners. However, since combustion is stable only in a narrow range of air-fuel ratios close to the stoichiometric mixing ratio, the total gas flow required to cool the permeable burner block is limited. This limitation severely limits the technical parameter changes required when spraying various substances, which causes droplets of the liquefied fuel to reach the burner and is therefore a frequent technical problem. This problem,
It always occurs when using propane and heavier fuels. When the droplets of fuel evaporate in the burner, the air-fuel ratio is greatly reduced, and combustion becomes unstable.

Furthermore, since the combustion temperature exceeds the melting temperature of most types of spray substances (1900 ° C. for propane-air mixtures, and 1900 for heavier fuels).
Above C), at least the surface of the spray particles is melted and actively oxidized by the oxygen in the jet,
Because of this, the HVAF coating is highly oxidized. On the other hand, it is clear that spraying unmelted solid particles substantially suppresses oxidation of the material in the spray. Anatoley Arkimov
Alkimov) and co-inventors were granted a patent for the gas-dynamic spray method of applying the coating (US Pat. No. 5,302,414). In this method, supersonic jets are formed by the expansion of a compressed gas having a temperature well below the melting temperature of the spray material. The coating forms during the bombardment of solid particles, which are not heated during welding and are not even partially oxidized. However, the coating formed of unheated particles is considerably more porous than the HVOF coating. Attempts to preheat the compressed gas with an electric heater have little effect on the quality of the coating, but on the other hand only make the device bulky.

Accelerating the particles below the melting point of the spray substance,
When both heating is possible, HVOF and H
The use of the VAF approach seems more promising in the future. James Browing
In U.S. Pat. No. 5,271,965, and also in the Journal of Thermal Spray T
echnology, December 1992, p. 289, 1 (4), Technical Note. He believed that the solid particles would be melted by the release of kinetic energy when bombarding the substrate. Thus, particle velocity is an important factor in coating formation. The problem is that in the known HVOF and HVAF devices the drop in gas temperature in the burner is always accompanied by a slowing of the gas velocity. As a result, the particle velocity decreases. To solve this problem, a unique solution was devised. For example, in order to keep the particles in a solid state during spraying, J. Browning proposed spraying water droplets of water to cool the jet in the nozzle below the melting point of the substance. (US Pat. No. 5,330,798). This water jet does not affect the combustion process itself. The obvious disadvantage of this device is the reduced efficiency of the device and the complexity of the procedure.

[0010]

The decrease in gas velocity due to the decrease in temperature described above does not only cause problems in spraying solid particles by the HVOF and HVAF techniques to deposit good quality coatings. It doesn't stop. In practice, reducing the gas temperature as much as necessary without destabilizing the combustion is not possible with prior art devices.

As is well known, stable combustion of an oxidant gas-fuel mixture at a high flow rate gas is achieved in a relatively narrow range where the mixing ratio of oxidant and fuel is close to the stoichiometric mixing ratio. To be The maximum temperature of combustion is achieved in this range. For example, for oxygen-propane mixtures, the stoichiometric mixing ratio is about 5: 1 by volume and the maximum combustion temperature is 2
Over 800 degrees C. Excess oxygen reduces the combustion temperature. In the case of oxygen-propane, this mixing ratio is 2.5:
1, the combustion temperature is about 2500 degrees C. If the oxygen content is further increased, the combustion will stop. For air-propane mixtures, the stoichiometric mixing ratio is about 2 by volume.
It becomes 5: 1, and the maximum combustion temperature is about 1900 ° C.

Even if hot walls are present in the permeable burner block, if the mixing ratio fluctuates by more than 10%, the combustion of the mixture will not continue. This situation is shown in US Pat. No. 5,932,293. Thus, H
In the VAF approach, it is virtually impossible to lower the gas temperature by increasing the air or propane content above the stoichiometric mixing ratio. Note that the gas temperatures described above are above the melting point of most commercial alloys used for thermal spraying. In this way, at least the surface of the spray particles is melted, resulting in a rapid oxidation of the material during spraying. For example, the use of fine particles of 20 micrometers or less creates serious problems.

The present invention thus provides a low oxidation, high density coating and agglomerates by rapid thermal spraying of particles that have a particle velocity approximately equal to the gas jet velocity and that are heated but do not melt. And a method of forming a coating or agglomerates by means of this spray device.

[0014]

SUMMARY OF THE INVENTION A rapid thermal spray apparatus according to the present invention comprises an oxidant-fuel mixing assembly, an internal burner, an igniter, an expansion nozzle and a spray substance delivery unit. Further, the apparatus includes a catalytic member within the internal burner to increase the pressure and flow rate of the oxidant gas or fuel beyond the stoichiometric mixing ratio or to add an inert gas to the mixture. The combustion temperature of the mixture is then lowered below the melting point of the spray substance.

In the present invention, the catalytic member in the internal burner performs at least two main functions.
First, the catalytic member significantly lowers the ignition temperature of the oxidant gas and fuel mixture. As a result, it is possible to significantly increase the total gas flow rate without risking overcooling of the catalyst surface which would burn the combustible mixture. Second, the catalyst member adsorbs the reaction gas on the surface of the catalyst, causing a combustion reaction at virtually any concentration of gas. If the surface of the catalyst is sufficiently large, it is possible to promote combustion under the proper mixing ratio of the oxidant gas and the fuel. Thus, the presence of a catalyst can increase the pressure and flow rate of the oxidant gas or fuel beyond the stoichiometric mixing ratio, or can add other inert gases such as nitrogen to the mixture. , Which cools the gas to a selected temperature without destabilizing the combustion. On the other hand, for spray materials with a high melting point, it is possible to sufficiently increase the pressure and flow rate of both the oxidant gas and the fuel by using an internal burner with a catalyst, which allows the total energy of the jet to be increased. To increase.

An important factor is that the increase in gas pressure and flow rate effectively compensates for the loss of gas velocity in the nozzle while reducing temperature. Moreover, the gas density is increased. As a result, the velocity of the spray particles does not decrease with decreasing temperature. On the contrary, a significant increase in particle velocity makes two new elements available. That is,
(A) Fine particles such as 1-20 micrometers or less can be sprayed by accelerating to a velocity of a gas jet. (B) Since the nozzle is not clogged with solid particles, it is possible to use a nozzle having a length as long as necessary to accelerate the particles. In the present invention, the particle velocity is at least 600 m / s to 800 m / s when using an air-propane combustion mixture.
s.

In the apparatus and method of the present invention, the catalyst member has one catalyst selected from the following catalyst group, and the catalyst group includes platinum, palladium,
Noble metals such as rhodium, or one or more binary oxides of the precious metals and rare earth metals (Ce, La, Nd, etc.), or one or more binary oxides formed by barium, strontium, rare earth metals, etc. Or other catalysts that withstand and use high temperature oxidation and that can reduce the ignition temperature of the oxidant gas-fuel mixture.

The catalytic member is in the form of a wire or wire mesh insert, or as a coating on the walls and passages of the internal burner components, or of at least one porous, perforated hole disposed within the internal burner. It is formed as a coating on some or powdered ceramic supports. The catalyst coating can be applied only to those surfaces that require combustion, limiting combustion to the required extent and protecting the other surfaces of the burner from overheating.

The rapid thermal spray device may further comprise at least one further internal burner in the form of a ring surrounding the first inner expansion nozzle and at least one further expansion nozzle. Such a series configuration of the burner and the nozzle is configured to further accelerate the particles and gradually and uniformly heat the particles at a temperature equal to or lower than the melting point of the spray substance.

The substance delivery unit of the present invention is capable of delivering either powder or wire into the device.
In the case of powder stock, the substance distribution unit comprises at least one injection device for delivering powder particles to a selected location in the internal burner or / and in the expansion nozzle. In a preferred embodiment, the powder injection device is located in the axial position of the internal burner, which maximizes the heating and acceleration efficiency of the device.

In the case of wire stock, the substance delivery unit is a two wire electric arc device for delivering the tip of the wire melted by the electric arc at the axial position of the internal burner or expansion nozzle. Is configured. In a preferred embodiment of the apparatus and method, the melted wire is atomized into fine particles that are accelerated and cooled by a high velocity gas jet produced by the combustion of a mixture of oxidant gas and excess fuel. Fuel flow above stoichiometry not only lowers the gas temperature below the melting point of the spray material, but also creates a reducing environment within the jet, thereby inhibiting any oxidation of the material that may occur during spraying. . The lower temperature jet allows coating from a closer distance between the nozzle and the substrate, so the jet is rarely diluted with the air that is ejected from the atmosphere, providing protection against oxidation by unburned fuel. Be more efficient.

[0022]

DETAILED DESCRIPTION OF THE INVENTION The present invention can be readily understood by reference to FIG. 1, which is a longitudinal cross-sectional view of a rapid thermal spray device. FIG. 1 shows a cross section of a rapid thermal spray device with an internal burner having a catalytic element made as a wire mesh insert. The device works with air and gaseous fuel mixtures. The preferred embodiment of this device comprises a mixing assembly formed by a fuel supply tube 1, an air supply tube 3, an air distributor 5 and a mixing block 6. The device further comprises in section H a catalytic burner formed from the catalytic member 8 made as a wire mesh insert. The downstream portion of compartment H acts as a collector for the gaseous products of combustion. The gas collecting housing 9 surrounds the compartment H. Finally, the preferred embodiment comprises a gas expansion nozzle 10 and a substance discharge unit in the form of a powder injection device 2. These parts are the main body housing 7, the main body rear housing 4, and the nozzle housing 1.
It is incorporated in a cylindrical body consisting of 1 and 1.

In this preferred embodiment, compressed air reaches the air distribution compartment A through the air supply tube 3. A part of this air enters the cooling zone B through the through hole C of the distributor 5 and reaches the cooling passage D,
Cool the device. This part of the air is the nozzle cooling passage D
It flows out of the device through 1 and forms an annular flow around the main gas jet. The other part of the air flows from the air distribution section A through the air holes E of the mixing block 6 into the mixing section F. A gaseous fuel such as propane or propylene is supplied to the mixing section (mixture distribution section) F by the fuel supply tube 1. As the compressed air expands from the small caliber air holes E into the larger mixing compartment F, this air ejects the fuel and forms a mixture of air and fuel. This mixture is mixed with the mixture outlet hole G of the mixing block 6.
Through a portion of the compartment H containing the catalytic member 8. This part of the compartment H serves as the combustion chamber. The mixture is ignited by a spark plug or an incandescent device (not shown) inside the catalyst member 8 and burns on the surface of the catalyst. The gas produced by the combustion expands in the gas expansion nozzle 10 to form a high-speed jet. The jet reaches supersonic velocity as it expands from the gas expansion nozzle 10 into the atmosphere. The particles of the spray substance are delivered to the axial center position of the compartment H via the powder injection device 2 by a carrier gas such as compressed nitrogen. The particles pass through the compartment H and the nozzle 10 and are heated and accelerated by the gas jet produced by the combustion to form an energized particle stream I. The particles impact the substrate J to form a coating or agglomerate.

In the present invention, the catalytic member in the internal burner performs at least two main functions.
First, it greatly reduces the ignition temperature of the mixture of oxidant gas and fuel. This mechanism is based on the fact that oxygen and fuel molecules are involved in a reversible redox reaction on the surface of the catalyst to lower the activation energy of these intermolecular reactions.
Thus, it is possible to significantly increase the total gas flow rate without the risk of overcooling the catalyst surface which would ignite the combustible mixture. Second, the catalytic member adsorbs reactive gases at the surface of the catalyst, causing these gases to undergo combustion reactions at any practical enrichment. Due to the very large surface of the catalyst, it is possible to promote combustion at any realistic mixing ratio of oxidant gas and fuel.
As a result, in the presence of a catalyst, combustion is inhibited by increasing the pressure and flow rate of the oxidant or fuel beyond the stoichiometric mixing ratio, or by adding another inert gas such as nitrogen to the mixture. It is possible to cool the gas to a selected temperature without being stable. In particular, by providing the catalytic member 8 for combustion chambers of the same size, the air flow rate can be increased from 10-12 cubic meters per minute without the catalytic member to 20-25 cubic meters. Which reduces the jet temperature from 1900 ° C to 1000 to 1200 ° C. Of course, it is also possible to increase the pressure and flow rate of both the oxidant gas and the fuel passing through the catalytic burner, which increases the total energy of the jet. This is effective in spraying a substance having a high melting point such as a refractory metal or a titanium alloy.

Increasing the gas pressure and flow rate in this manner effectively compensates for the loss of gas velocity at the nozzle while lowering the temperature. Moreover, the gas density also increases. As a result, the velocity of the sprayed particles does not decrease with decreasing temperature. On the contrary, with a significant increase in particle velocity, two new factors become available: The first element allows fine particles of powder material, such as 1-20 micrometers or less, to be sprayed by accelerating to the velocity of a gas jet. The second factor is that there is no clogging of the nozzle with solid particles, allowing the use of nozzles as long as needed to accelerate the particles.

In the above-described preferred embodiment, the catalyst member 8 has one catalyst selected from the following group, and this group includes a noble metal such as platinum, palladium and rhodium, or the above noble metal. And one or more binary oxides of rare earth metals (Ce, La, Nd, etc.),
Alternatively, one or more binary oxides formed of barium, strontium, rare earth metals, etc., or those that withstand and use high temperature oxidation and that can lower the ignition temperature of the oxidizer-fuel mixture. Includes certain other catalysts.

The catalyst member 8 is not limited to being formed in the form of a wire mesh insert, but instead of this wire mesh insert, it is placed as a coating on the walls and passages of the internal burner or is arranged on the internal burner. It can be formed as a coating on at least one ceramic support which is porous, perforated or in powder form. The catalyst coating can be applied only to those surfaces that require combustion, limiting combustion to the extent required and protecting the other surfaces of the burner from overheating.

Now, a preferred embodiment of a high velocity air-fuel system comprising at least one further internal burner having an annular shape surrounding the first inner expansion nozzle, and one further nozzle, As shown in FIG. The primary burner and nozzle operate as described above. Another compartment N is arranged between the outlet of the inner expansion nozzle 10 and the nozzle housing 11. In compartment N, the secondary burner is surrounded by an inner catalyst support ring 13 made of SiC-AI203 ceramic and an outer catalyst support ring 14 made of AI203-based ceramic. The outer cylindrical surface of the inner ring 13 and its downstream side and the inner cylindrical surface of the outer ring 14 are coated with a catalytic coating 17 such as platinum or platinum-cerium oxide. The secondary expansion nozzle 15 is made of SiC-ceramic. The secondary expansion nozzle 15 is fixed to the nozzle housing 11 with a nozzle nut 16. The fuel for the secondary burner is supplied through the secondary fuel supply tube 12. The fuel in the secondary burner is mixed in the secondary compartment K with the cooling air coming from the cooling passages D. The mixture enters the secondary burner through the secondary mixing outlet hole L, which is in the form of a slot M surrounded by the catalyst surface 17 of the inner catalyst support ring 13 and the outer catalyst support ring 14. Made of. The mixture is ignited in a back-flash of a primary gas jet expanding from an inner nozzle 10, which is a gas expansion nozzle. Combustion products are
It expands into the secondary nozzle 15 and mixes with the primary jet, which carries the stream of particles. Such an arrangement results in a very gentle and uniform heating of the spray particles. further,
This configuration has a great effect on particle acceleration. In this preferred embodiment, the particle velocity is 600 m /
over s. In particular, a secondary nozzle with a length of 200 mm,
With 625 alloy powder with an average particle size of 10 μm, the average particle velocity when using an air-propane combustible mixture reaches 800 m / s.

Another preferred embodiment is shown in FIG. This figure is a schematic longitudinal cross-sectional view of a rapid thermal spray device having an internal burner with a catalytic member in the form of a coating on the passages and downstream surface of a catalytic ceramic support. Then, the spray material is injected at the axial position of the expansion nozzle, and the spray material is formed by melting the two consumable wire tips by an electric arc machine. The apparatus comprises a body housing 107 which holds an inner catalyst support ring 113 made of SiC-AI203 ceramic and an outer catalyst support ring 114 made of AI203 ceramic. The burner is in the form of a combustion slot M formed between these two rings 113, 114. The slots M formed by the cylindrical surfaces of both rings and the downstream surface of the inner ring 113 are coated with a catalytic coating made of barium, lanthanum oxide or metallic platinum. Main body rear housing 10
5 is attached to the main body housing 107, and the cooling air supply tube 103, the combustible mixture supply tube 101, and the two contact tubes 10 for directing the two spray wires 120 to the axial position of the expansion nozzle 110.
Hold 2 and. The position of the contact tube 102 is adjusted by the positioning member 106 arranged in the main body housing 107. The collective housing 109 is attached to the front part of the main body housing 107. The outlet is formed in the shape of the expansion nozzle 110. The front portion of the main body housing 107 is covered with an air lid 111.

A flammable mixture, for example a mixture of air and propane, is fed by a tube 101 into a ring-shaped mixture distribution compartment F in the body housing 107. The mixture then flows through the combustion slot M and burns at the surface of the catalyst coating 117. A spark plug is used to initiate combustion (not shown in Figure 3). Even if there is a gas that does not undergo a combustion reaction here, this gas burns on the downstream surface of the inner ring 113 covered with the catalyst coating 117. The gaseous products of combustion are directed to the collecting compartment H by the collecting housing 109 and then to the expansion nozzle 110. The gas jet expands from the nozzle 110 to reach supersonic velocity.

The two consumable wires 120 for spraying are
It is supplied to the axial center position of the nozzle 110 through the contact tube 102 by the wire feeding mechanism 140. Electric arc 120a held by a power supply 130 of the arc machine
Melts the tip of the wire in the nozzle 110. The gas jet of combustion products atomizes and accelerates the tip of this melted wire, forming a stream I of energized particles. The particles strike the substrate J to form a coating.

Combustion in slot M is carried out in excess of stoichiometric mixture fuel, which serves two purposes. That is, (a) the gas jet of combustion products is cooled below the melting point of the spray substance to effectively cool the atomized particles. (B) Protect the spray particles from oxidation in the jet. In particular, for a mixture of air and propane, the stoichiometric mixing ratio of 3 to 4 can be achieved without stopping combustion by using the catalyst support member.
More than twice, the flow rate of propane can be increased.
The cooling air is supplied to the air distribution section A by the supply tube 103. This cooling air is supplied to the main body housing 10
7 through the cooling passage D and flows into the cooling passage D1 between the air lid 111 and the collective housing 109, and the nozzle 110
And exits the device around the to form an annular flow. This flow wraps the high velocity jet of gas and suppresses the injection of oxygen from the atmosphere.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Described in the preferred embodiment shown in FIG.
671-type alloy powder (Ni-based 43% Cr-0.5% Ti-0.9% S) with a particle size of 10-45 μm in a device equipped with two internal burners and two nozzles.
The coating of i) was sprayed. The catalyst member was made of AI203-12% SiO2 ceramic coated with a platinum catalyst, and was made in the shape of a porous catalyst support ring in which the hole portions occupied 64% in total. The device was operated at an inlet pressure of 8.4 bar and an air flow rate of 20 cubic meters per minute and a pressure of 5 bar and a propane flow rate of 2 kilograms per minute. The total air flow rate was increased to 70% above the stoichiometric mixing ratio and the exhaust gas temperature was reduced to approximately 1400 degrees Celsius. 0.4mm thick coating, type 10
It was welded to an 18-carbon steel substrate, and a test piece for welding strength measurement based on the ASTM C633 standard was prepared. Further, for the microscopic examination of the coating, a sample of 75 × 25 × 6 mm having the same coating was prepared. In addition, ISO4
Diameter 25 mm, thickness 6 mm, pore diameter 2 μm for measuring gas permeability of coating according to 022 standard
A porous 316 stainless steel filter sample of 1. was similarly coated. The visual oxide content and porosity of the coatings were measured on the specimen cross sections by metallographic image analysis methods. The total oxygen content of the coating is determined by a method of reducing melting in an atmosphere of an inert carrier gas stream (LECO Oxy.
gen Analyzer oxygen analyzer). The total oxygen content of the powdered raw material is 0.06%
Met.

The following characteristics were obtained for this coating: (1) visual porosity,% not measured (2) visual oxide content,% not measured (3) total oxygen content,% 0.16 (4) Gas permeability, not measured (hence 0.01 square nanometer or less) (5) Bonding strength 80.0 MPa or more (collapsed at epoxy bonded part)

By comparison, when spraying the above materials by the HVOF and HVAF techniques of the prior art,
Oxygen content of coating is 0.01% to 3.5%
Between the values of the present invention and one digit larger than that of the present invention. The gas permeability of prior art HVOF and HVAF coatings (corresponding to the penetration of the porous part) was measured to be 0.05 to 2.0 square nanometers, which is considerably higher than in the present invention. Thus, the deposited coating according to the present invention exhibits a high density and a significantly lower oxygen content when compared to the HVOF and HVAF techniques of the prior art.

[Brief description of drawings]

FIG. 1 is a schematic longitudinal cross-sectional view of a rapid thermal spray device having a wire mesh insert shaped catalyst member forming an internal burner. The spraying of the spray substance takes place in the form of a powder at the axial center of the burner.

FIG. 2 is a schematic longitudinal cross-sectional view of a rapid thermal spray apparatus having a wire mesh insert shaped catalyst member, the apparatus comprising another catalyst having an annular shape around a first inner expansion nozzle. It has a burner and a separate nozzle.

FIG. 3 shows on the catalytic ceramic supporter passages forming an internal burner and on the downstream surface,
1 is a schematic longitudinal cross-sectional view of a rapid thermal spray device having a coated catalyst member. The spray substance is sprayed toward the axial position of the expansion nozzle, and the tip portions of the two consumable wires that are melted by the electric arc machine are sprayed.

[Explanation of symbols]

1 Fuel supply tube 2 Powder injection device 3 Oxidant (or air) supply tube 5 air distributor 6 mixed blocks 8 Catalyst member 9 gas collection housing 10 Gas expansion nozzle 12 Secondary combustion supply tube 13 Inner catalyst support ring 14 Outer catalyst support ring 15 Secondary expansion nozzle 101 Combustible mixture supply tube 102 contact tube 103 Cooling air supply tube 109 collective housing 110 expansion nozzle 113 Inner catalyst support ring 114 outer catalyst support ring 120 spray wire 120a electric arc 130 power supply A air distribution section B cooling compartment C through hole D cooling passage E Air hole F mixed section G mixture outlet hole H section I Particle flow J board K secondary division L secondary mixing section M burning slot N division

─────────────────────────────────────────────────── ─── Continuation of the front page (73) Patent holder 502144349 Verstoke Andrew A. Andrew A. Verstak USA Virginia 23112 Midlothian Water-Foodway 1 D 2704 (72) Inventor Baranovsky Via Cheslav E. USA Virginia 23233 Richmond Stonebriarrain 12700 (72) Inventor Verstoke Andrew A. USA Virginia 23water Midwater Foodway 1 D 2704 (56) Reference JP-A-5-138084 (JP, A) JP-A-10-54561 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 4 / 00-4/18 B05B 7/20 F23C 11/00

Claims (12)

(57) [Claims] 1. A rapid thermal spray apparatus for depositing a substance onto a substrate, the mixing assembly being designed to mix an oxidant gas and a fuel; An internal burner for combustion of the mixture, an igniter for initiating combustion of the mixture, a gas expansion nozzle configured to receive the products of combustion of the mixture to form a high velocity gas jet, A spray delivery material to the jet, forming a stream of particles accelerated by the jet and heated below the melting point of the spray material, the stoichiometric mixing Pressure and flow rate of the oxidant gas beyond the ratio
And a catalyst member for lowering the combustion temperature of the mixture below the melting point of the spray substance in the internal burner. 2. A replacement for increasing the pressure and flow rate of the oxidant gas.
Instead, increase or deactivate the pressure and flow of the fuel.
A characteristic gas is added to the mixture.
1. The high-speed thermal spray device described in 1. 3. The catalyst member is platinum or palladium,
At least one noble metal such as rhodium, or one or more binary oxides of the noble metals and rare earth metals, or one or more binary oxides formed of barium, strontium, rare earth metals, or the like, or Fast heat according to claim 1 or 2 , having one catalyst selected from the group comprising other high temperature resistant catalysts capable of lowering the ignition temperature of the mixture of oxidant and fuel. Spray equipment. 4. At least one of said catalytic member as a wire or wire mesh insert, or as a coating on the walls and passages in said internal burner where combustion is desired to occur, or on said internal burner. The rapid thermal spraying device according to claim 1 or 2, which is formed as a coating on a ceramic support portion. 5. Further at least one further internal burner having an annular shape around the expansion nozzle for further accelerating the particles and heating uniformly below the melting point of the spray substance. The rapid thermal spray device according to claim 1 or 2 , further comprising at least one additional expansion nozzle. 6. The substance delivery unit comprises at least one injection device whereby the particles of the spray substance are introduced into the internal burner or into the expansion nozzle at the selected location. The high-speed thermal spray device according to claim 1 or 2 , wherein the high-speed thermal spray device is delivered at a high temperature. 7. The substance delivery unit is a double wire electric arc device, the device comprising: a tip portion of a wire melted by an electric arc at an axial position of the internal burner or the expansion nozzle. Rapid thermal spray device according to claim 1 or 2 , characterized in that it is arranged to deliver. 8. A spray material for delivery to the jet
Characterized in that the particles are 1 to 20 micrometers
The rapid thermal spray device according to claim 1 or 2. 9. A method of forming a coating or bulk material by depositing a material on a substrate with a rapid thermal spray apparatus, the method comprising mixing an oxidant gas and a fuel of a mixing assembly. Igniting and burning the mixture of oxidant and fuel in an internal burner, forming a high velocity gas jet of combustion products of the mixture in a gas expansion nozzle, accelerated by the jet, Introducing a selected spray substance into the jet by a substance delivery unit to form a stream of particles heated below the melting point of the spray substance, the method further comprising: The pressure of the oxidant above the stoichiometric mixing ratio
Using a catalytic member provided within the internal burner for increasing the force and flow rate to reduce the combustion temperature of the mixture below the melting point of the spray substance.
A method of forming a coating or bulk material. 10. The method determines the pressure and flow rate of the oxidant.
Instead of increasing the pressure and flow rate of the fuel,
Or an inert gas is added to the mixture.
Forming a coating or lumpy material according to claim 9
how to. 11. The method comprises introducing the spray material into the rapid thermal spray device in the form of a powder that does not melt in the jet.
11. A method of forming a coating or lump as claimed in 9 or 10 . 12. The method comprises introducing the spray material into the rapid thermal spray apparatus as the tip of a wire, rod or other elongated member melted by an electric arc, the burner and gas expansion nozzle. Wherein the fuel comprises atomizing, accelerating, and cooling the spray material with the jet in excess to inhibit oxidation that may occur during the formation of the coating or agglomerates. Claim to be
11. A method of forming a coating or agglomerate according to 9 or 10 .