JP2002336744A - High speed heat spray device for forming substance and method for forming coating or lumped substance by using the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the oxidation of a fused spray-deposited substance on a substrate by lowering a combustion temperature and to spray a coating high in density and low in oxidation by the high speed heat spray of particles. SOLUTION: A mixing section F in which a fuel supply tube 1 and an air supply tube 3 are made to communicate with each other, a gas expansion nozzle 10 which receives the products of combustion from a burner for the combustion of a mixture of the fuel and air and constitutes a high speed gas jet, and the flow I of particles which supplies a spray substance from a powder ejection device 2 to the gas expansion nozzle 10 and is heated at a temperature equal to or below the melting point of the spray substance are formed. The fuel can be burned easily, and the air is added with an inert gas to be controlled within a concentration range to prevent the generation of accidental fire.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame spray apparatus for depositing a coating and a bulk material by a thermal spray technique, and a flame spraying method for forming a coating or a bulk material by the spray apparatus. In particular, the present invention relates to a high speed oxidizer-fuel spray apparatus and method, which sprays unmelted particles at a particle velocity approximately equal to the gas jet velocity to provide low oxidation, high density coatings and agglomerates. FIELD OF THE INVENTION The present invention relates to a high-speed flame spray device suitable for forming a material and a method for forming a coating or a bulk material by the spray device.

[0002]

2. Description of the Related Art Generally, a flame spraying apparatus and a method for depositing a coating and a lump material by a thermal spraying method are based on a high-speed oxidizing gas-fuel spray. Are known as high velocity oxy-fuel (HVOF) sprays. Similarly, if the oxidant gas is air or oxygen-enriched air, the high velocity air-fuel (H
VAF) spray.

[0003] This thermal spray is widely used to form metals and ceramics in the form of coatings or agglomerates on various substrates. Most thermal spraying techniques use the energy of a hot gas jet to heat and accelerate particles of spray material, which impinge on a substrate to form a coating.

In general, high-speed oxy-fuel (HVOF) systems burn fuel and oxygen in an inner burner, typically under elevated pressures to 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. The combustion gases expand from the burner into the discharge nozzle or barrel to reach the speed of sound. Further, when expanded into the atmosphere or into a divergent nozzle section such as a Laval nozzle, a supersonic jet is created. For this reason, this technique is called high speed.

[0005] The first aforementioned device is a James A.
Invented by James A. Browning (U.S. Patent Nos. 4,342,551 and 4,343,605, issued August 1982). Many improvements to the HVOF injection gun heat the spray material with better efficiency,
The goal was to accelerate (US Pat. No. 4,370,538
No. 4, 416, 421, 4, 540, 121, 4, 568, 019,
Nos. 4,634,611, 4,836,447, 5,019,686, 5,2
06, 059, 5, 535, 590). Although this HVOF means forms a relatively dense coating, it melts the particles, at least in part, depositing a relatively high oxide-containing material, which significantly activates the surface of the particles. Incomplete combustion or air entrainment from the atmosphere (ejection)
Thus, the molten surface of the particles rapidly oxidizes because the jet always contains gaseous oxygen. In addition, these measures are quite expensive because they consume large amounts of compressed oxygen. Finally, melted spray particles can clog long nozzles, causing many problems in the operation of HVOF devices.

[0006] High-speed air-fuel (HVAF) devices were first conceived as an inexpensive alternative to 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, U.S. Pat.
Design improvements were made in 5,085 and 5,520,334. A major problem with this device is that high gas flow rates cause combustion instability because the flame propagation velocity of the fuel-air mixture is two orders of magnitude slower than the fuel-oxygen mixture. With a relatively long internal burner, the combustion is stable and complete. However, this makes it impossible to introduce the spray powder into the axial position between the burner chamber and the nozzle.
That is, if the burner chamber is too long, the spray particles cannot pass through the burner chamber. If the particles are ejected to the nozzle side wall instead of the injection at the axis position, clogging of the nozzle occurs, and HVO using the injection at the axis position
A bigger problem arises than the F device. The use of hydrogen or methane for ignition of combustion and as a pilot flame is neither practical nor safe for many HVAF guns.

[0007] One of the inventors of the present invention (US Pat. No. 5,932,293) is Vladimi Verasimenko.
r Belashchenko) and Viacheslav Baranovski introduced a significant improvement in the HVAF design, namely a transparent burner block in the internal burner room. When the air-fuel mixture is heated above the auto-ignition temperature, the hot walls and passages of the permeable burner block burn the mixture continuously, thereby stabilizing combustion even in relatively small burners. However, since combustion is only stable over a narrow range of air-fuel ratios close to the stoichiometric ratio, the total gas flow required to cool the permeable burner block is limited. This limitation greatly limits the technical parameter changes required when spraying various materials, and often causes technical problems as liquefied fuel droplets reach the burner. This problem,
Occurs whenever propane and heavier fuels are used. When the fuel droplets evaporate in the burner, the air-fuel ratio is greatly reduced, and the combustion becomes unstable.

Furthermore, because the combustion temperature exceeds the melting temperature of most types of spray materials (1900 ° C. for propane-air mixtures and 1900 ° C. for heavier fuels)
At least the surface of the spray particles is melted and actively oxidized by oxygen in the jet,
Because of this, the HVAF coating is significantly oxidized. On the other hand, it is clear that spraying unmelted solid particles substantially suppresses oxidation of the material in the spray. Anatoley Archimov
Alkimov) and co-inventors were granted a patent for a gas mechanical spray method of applying a coating (US Pat. No. 5,302,414). In this method, a supersonic jet is formed by expansion of a compressed gas having a temperature well below the melting temperature of the spray material. The coating forms during the impact of the solid particles, but the particles are not heated during welding and are not partially oxidized. However, coatings formed with unheated particles are significantly more porous than HVOF coatings. 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 equipment huge.

Accelerating the particles below the melting point of the spray material,
When both heating are possible, HVOF and H
The use of the VAF approach seems to be more promising in the future. James Browing
In US Patent No. 5,271,965 and in the Journal of Thermal Spray Tec
hnology, December 1992, p. 289, Technical Note 1 (4). He believed that solid particles were melted by the release of kinetic energy when impacting the substrate. Thus, particle velocity is an important factor in coating formation. The problem is that in known HVOF and HVAF devices, a decrease in gas temperature in the burner is always accompanied by a reduction in gas velocity. As a result, the particle velocity decreases. A unique solution has been devised to solve this problem. For example, to keep particles in a solid state during spraying, J. Browning proposes to spray droplets of water to cool the jet in the nozzle below the melting point of the material. (US Patent No. 5,330,798). This water droplet injection does not affect the combustion process itself. The obvious disadvantages of this device are the reduced efficiency of the device and the complexity of the procedure.

[0010]

The reduction in gas velocities due to the above-mentioned reduction in temperature is only due to the problem of spraying solid particles by the HVOF and HVAF techniques to deposit good quality coatings. It doesn't stop. In practice, it is not possible with known devices to reduce the gas temperature as much as necessary without making the combustion unstable.

As is well known, stable combustion of an oxidant gas-fuel mixture with a high flow rate gas can be achieved in a relatively narrow range where the mixing ratio of oxidizing agent to fuel is close to the stoichiometric mixing ratio. Can be The highest temperature of combustion is achieved in this range. For example, for an oxygen-propane mixture, the stoichiometric mixing ratio is about 5: 1 by volume and the maximum combustion temperature is 2
Exceeds 800 ° C. Excess oxygen lowers the combustion temperature. In the case of oxygen-propane, this mixing ratio is 2.5:
1 and the combustion temperature is about 2500 degrees C. If the oxygen content is further increased, the combustion stops. In the case of an air-propane mixture, the stoichiometric mixing ratio is about 2 by volume.
5: 1, and the maximum combustion temperature is about 1900 ° C.

[0012] Even if hot walls are present in the permeable burner block, if the mixing ratio fluctuates by 10% or more, the combustion of the mixture does not continue. This situation is illustrated in US Pat. No. 5,932,293. Thus, HV
With the AF approach, it is virtually impossible to reduce the gas temperature by increasing the air or propane content beyond the stoichiometric mixing ratio. Note that the gas temperatures mentioned 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 rapid oxidation of the substance during spraying. For example, the use of fine particles of 20 micrometers or less creates serious problems.

Accordingly, the present invention provides a method for forming low oxidation, high density coatings and agglomerates by high speed thermal spray of particles having a particle velocity approximately equal to the gas jet velocity and being heated but not melted. And a method for forming a coating or a lump material by the spray device.

[0014]

SUMMARY OF THE INVENTION A high speed thermal spray device according to the present invention includes an oxidizer-fuel mixing assembly, an internal burner, an igniter, an expansion nozzle, and a spray material delivery unit. Further, the apparatus includes a catalyst member within the internal burner, thereby increasing the pressure and flow rate of the oxidizing gas or fuel beyond the stoichiometric mixing ratio, or adding an inert gas to the mixture. The combustion temperature of the mixture is lowered below the melting point of the spray material.

In the present invention, the catalyst member in the internal burner performs at least two main functions.
First, the catalyst member significantly lowers the ignition temperature of the mixture of oxidant gas and fuel. Thus, it is possible to significantly increase the total gas flow without risking overcooling of the catalyst surface which is likely to burn the combustible mixture. Second, the catalyst member adsorbs the reactant gas on the surface of the catalyst, causing a combustion reaction at virtually any concentration of the gas. If the surface of the catalyst is sufficiently large, it is possible to promote combustion under a proper mixing ratio of oxidant gas and fuel. Thus, depending on the presence of the catalyst, it is possible to increase the pressure and flow rate of the oxidizing gas or fuel beyond the stoichiometric mixing ratio, or to add other inert gases such as nitrogen to the mixture. This cools the gas to the selected temperature without destabilizing the combustion. On the other hand, for spray substances with a high melting point, the use of catalyzed internal burners allows the pressure and flow rate of both the oxidant gas and the fuel to be sufficiently increased, thereby increasing the total energy of the jet. Increase.

An important factor is that increasing the pressure and flow rate of the gas effectively compensates for the loss of gas velocity in the nozzle while reducing the temperature. Moreover, the gas density increases. As a result, the velocity of the spray particles does not decrease with decreasing temperature. On the contrary, a considerable 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 almost the speed of a gas jet. (B) No clogging of the nozzles with solid particles allows the use of nozzles as long as needed 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 group of catalysts, and this group of catalysts includes platinum, palladium,
Noble metals such as rhodium, or one or more binary oxides of the noble metals and rare earth metals (such as Ce, La, Nd) or one or more binary oxides formed by barium, strontium, rare earth metal, etc. Or other catalysts that can withstand and be used at high temperatures and that can reduce the ignition temperature of the oxidant gas-fuel mixture.

[0018] The catalyst member may be in the form of a wire or wire mesh insert, or as a coating on the walls and passages of the components of the internal burner, or at least one porous, perforated hole disposed within the internal burner. Formed as a coating on a ceramic support which is in powder or powder form. Catalytic coatings can be formed only on surfaces that require combustion, limiting combustion to the required extent and protecting other surfaces of the burner from overheating.

The high speed thermal spray device may further comprise at least one further internal burner in an annular shape surrounding the first inner expansion nozzle and at least one further expansion nozzle. Such a series configuration of burner and nozzle is configured to further accelerate the particles and gradually and uniformly heat the particles at a temperature below the melting point of the spray material.

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 includes at least one injection device for delivering powder particles at a selected location in the internal burner or / and in the expansion nozzle. In a preferred embodiment, the powder injection device is located at the axis of the internal burner, thereby maximizing 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, which delivers the tip of the wire which is melted by the electric arc at the axis of the internal burner or expansion nozzle. Is configured. In a preferred embodiment of the apparatus and method, the melted wires are atomized into fine particles which are accelerated and cooled by a high velocity gas jet resulting from the combustion of a mixture of oxidant gas and excess fuel. A fuel flow rate greater than the stoichiometric mixing ratio not only lowers the gas temperature below the melting point of the spray material, but also creates a reducing environment in the jet, thereby suppressing any oxidation of the material that may occur during spraying. . The cooler jet allows for coatings from close distances between the nozzle and the substrate, so that the jet is rarely diluted with the air ejected from the atmosphere, thus providing protection against oxidation by unburned fuel. Be more efficient.

As described above, in the method and apparatus of the present invention, a catalyst is basically used. However, under special conditions, an apparatus without a catalyst or an apparatus using a catalyst may be used. The coating operation can be performed without the need. That is, hydrogen which is extremely easy to burn as fuel,
Lowering the combustion temperature by using at least one of acetylene, methane, ethane, and propane, and adding an inert gas such as argon to the oxidizing gas to control the concentration within a predetermined range that does not cause misfiring. Thus, oxidation of the deposited material on the base is prevented. In this way, the operation can be performed without reducing the repair cost and equipment cost of the apparatus and without replacing the deteriorated catalyst.

[0023]

DETAILED DESCRIPTION OF THE INVENTION The present invention can be readily understood by reference to FIG. 1, which is a longitudinal sectional view of a high speed thermal spray device. FIG. 1 shows a cross section of a high-speed thermal spray device with an internal burner having a catalyst member made as a wire mesh insert. This device operates on a mixture of air and gaseous fuel. A preferred embodiment of the 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 a catalyst burner in section H formed from a catalyst member 8 made as a wire mesh insert. The downstream portion of section H acts as a collector for the gaseous products of the combustion. The gas collecting housing 9 surrounds the section H. Finally, the preferred embodiment includes a gas expansion nozzle 10 and a substance discharge unit in the form of a powder injection device 2. These parts include the main body housing 7, the main body rear housing 4, and the nozzle housing 1
1 are incorporated in a cylindrical body.

In this preferred embodiment, the compressed air reaches the air distribution section A through the air supply tube 3. Some 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 supplied to 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 a mixing section (mixture distribution section) F by a fuel supply tube 1. As the compressed air expands from the small diameter air holes E into the large mixing section F, the 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.
And flows into a part of the section H having the catalyst member 8. This part of the section H performs the function of a 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 generated by the combustion expands into the gas expansion nozzle 10 to form a high-speed jet. This jet reaches supersonic speed when expanding from the gas expansion nozzle 10 into the atmosphere. The particles of the spray substance are delivered by a carrier gas, such as compressed nitrogen, via the powder injector 2 to the axis of the section H. The particles pass through the compartment H and the nozzle 10 and are heated and accelerated by the gas jet generated by the combustion to form an energized particle stream I. The particles strike the substrate J and form a coating or agglomerate.

In the present invention, the catalyst member in the internal burner performs at least two main functions.
First, the ignition temperature of the mixture of oxidant gas and fuel is greatly reduced. This mechanism is based on the fact that oxygen and fuel molecules are involved in a reversible oxidation-reduction reaction on the surface of a catalyst, and the activation energy of these intermolecular reactions is reduced.
Thus, it is possible to significantly increase the total gas flow without risking overcooling of the catalyst surface, which would ignite the combustible mixture. Second, the catalyst member adsorbs reactive gases at the surface of the catalyst, causing a combustion reaction at any realistic enrichment of these gases. Because of the very large surface of the catalyst, any realistic mixing ratio of oxidant gas and fuel can promote combustion.
As a result, in the presence of a catalyst, combustion is prevented 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 the selected temperature without making it stable. In particular, by providing a catalytic member 8 for a combustion chamber of the same dimensions, the air flow rate can be increased from 10-12 cubic meters per minute without this catalytic member to 20-25 cubic meters. This lowers the jet temperature from 1900 ° C. to 1000 to 1200 ° C. Of course, it is also possible to increase the pressure and flow of both the oxidant gas and the fuel passing through the catalytic burner, thereby increasing the total energy of the jet. This is effective in spraying a substance having a high melting point such as a heat-resistant 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 reducing the temperature. In addition, the gas density increases. As a result, the velocity of the sprayed particles does not decrease with decreasing temperature. On the contrary, with the 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 accelerated to the speed of the gas jet and sprayed. The second factor is that no clogging of the nozzle with solid particles allows the use of nozzles as long as needed to accelerate the particles.

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

The catalyst member 8 is not limited to being formed in the form of a wire mesh insert. Instead of the wire mesh insert, the catalyst member 8 is disposed as a coating on the wall or passage of the internal burner, or disposed on the internal burner. It can be formed as a coating on at least one porous, perforated or powdered ceramic support. The catalytic coating can be applied only to those surfaces that need to be burned, limiting the burn to the required range and protecting the other surfaces of the burner from overheating.

Now, a preferred embodiment of a high-speed 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 the nozzle operate as described above. Another section N is arranged between the outlet of the inner expansion nozzle 10 and the nozzle housing 11. In section 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 of the secondary burner is supplied by a secondary fuel supply tube 12. The fuel of the secondary burner is mixed with the cooling air coming from the cooling passage D in the secondary section K. The mixture flows into the secondary burner through a secondary mixing outlet hole L, which has the shape of a slot M surrounded by a catalyst surface 17 of an inner catalyst support ring 13 and an outer catalyst support ring 14. Consists of The mixture is ignited by a back-flash of a primary gas jet expanding from an inner nozzle 10, which is a gas expansion nozzle. The products of combustion are
It expands into the secondary nozzle 15 and mixes with the primary jet that carries the stream of particles. Such a configuration results in very gentle and uniform heating of the spray particles. further,
This configuration has a significant effect on particle acceleration. In this preferred embodiment, the particle velocity is 600 m /
exceeds s. In particular, a secondary nozzle 200 mm long,
For a 625 alloy powder with an average particle size of 10 μm, the average particle velocity when using an air-propane flammable mixture reaches 800 m / s.

Another preferred embodiment is shown in FIG. This figure is a schematic longitudinal sectional view of a high-speed thermal spray device, which has a catalytic member in the form of a coating in the internal burner on the passage of the catalytic ceramic support and on the downstream surface. The spray material is sprayed at the position of the axis of the expansion nozzle, and the spray material is formed by melting the tips of two consumable wires by an electric arc machine. This apparatus includes a main 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 ceramic based on AI203. 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 metal platinum. Main body rear housing 10
5 is attached to the main body housing 107 and includes a cooling air supply tube 103, a flammable mixture supply tube 101, and two contact tubes 10 for directing two spray wires 120 to the axial position of the expansion nozzle 110.
And 2 are held. The position of the contact tube 102 is adjusted by a positioning member 106 arranged on the main body housing 107. The collective housing 109 is attached to the front of the main body housing 107. The outlet is formed in the shape of the expansion nozzle 110. The front part of the main body housing 107 is covered with an air lid 111.

A combustible mixture, for example, a mixture of air and propane, is supplied by a tube 101 to a ring-shaped mixture distribution section F in the main body housing 107. Next, the mixture flows through the combustion slot M and burns on the surface of the catalyst coating 117. A spark plug is used to initiate combustion (not shown in FIG. 3). Here, even if there is a gas that does not undergo a combustion reaction, the gas burns on the downstream surface of the inner ring 113 covered with the catalyst coating 117. The gaseous products of the combustion are directed by the collecting housing 109 to the collecting section H and then to the expansion nozzle 110. The gas jet expands from nozzle 110 and reaches supersonic speed.

The two consumable wires 120 for spraying are:
The liquid is supplied to the axial center position of the nozzle 110 through the contact tube 102 by the wire feed mechanism 140. Electric arc 120a maintained by an arc machine power supply 130
Melts the tip of the wire in the nozzle 110. The gaseous jet of combustion products refines and accelerates the melted wire tip, forming a stream I of energized particles. The particles impact the substrate J to form a coating.

The combustion in slot M takes place with an excess of fuel above the stoichiometric mixture, thereby achieving two objectives. That is, (a) the gas jet of the combustion product is cooled below the melting point of the spray material to effectively cool the finely divided particles. (B) Protect the spray particles from oxidation in the jet. In particular, for a mixture of air and propane, the stoichiometric mixing ratio is reduced to 3 to 4 without stopping the combustion by using the catalyst supporting member.
More than twice, the flow rate of propane can be increased.
Cooling air is supplied to the air distribution section A by the supply tube 103. The 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.
Out of the device around to form an annular flow. This flow envelops the high velocity jet of gas and suppresses the entrainment of oxygen from the atmosphere.

As described above, in the method and apparatus of the present invention, a catalyst is basically used, but under special conditions, an apparatus without a catalyst or an apparatus using a catalyst may be used. The coating operation can be performed without the need. That is, hydrogen which is extremely easy to burn as fuel,
Lowering the combustion temperature by using at least one of acetylene, methane, ethane, and propane, and adding an inert gas such as argon to the oxidizing gas to control the concentration within a predetermined range that does not cause misfiring. Thus, oxidation of the deposited material on the base is prevented. In this way, the operation can be performed without reducing the repair cost and equipment cost of the apparatus and without replacing the deteriorated catalyst.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiment described in FIG.
A 671-type alloy powder having a particle size of 10-45 μm (Ni-based 43% Cr-0.5% Ti-0.9% S) 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 manufactured in the form of a porous catalyst support ring having a hole portion occupying a total of 64%. The apparatus was operated with an air flow of 20 cubic meters per minute at an inlet pressure of 8.4 bar and a propane flow of 2 kilograms per minute at a pressure of 5 bar. The total air flow was increased to 70% above the stoichiometric mixing ratio and the exhaust gas temperature was reduced to approximately 1400 ° C. Apply a 0.4 mm thick coating to Type 10
The test piece was welded to an 18 carbon steel substrate, and a test piece for measuring the strength of weldability based on the ASTMC633 standard was prepared. In addition, a test specimen of 75 × 25 × 6 mm having the same coating was prepared for the examination of the structure of the coating. Also, ISO4
To measure the gas permeability of the coating based on the 022 standard, the diameter was 25 mm, the thickness was 6 mm, and the pore diameter was 2 μm.
A similar coating was applied to a sample of porous 316 stainless steel filter. The visual oxide content and porosity of the coating were measured on specimen sections by metallographic image analysis. The total oxygen content of the coating can be determined by reducing melting in an atmosphere of an inert carrier gas stream (LECO Oxy
gen Analyzer oxygen analyzer). The total oxygen content of the raw material of the powder 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 (thus 0.01 square nanometers or less) (5) Bond strength 80.0 MPa or more (collapsed at epoxy adhesive part)

By comparison, when spraying the above substances by the HVOF and HVAF techniques according to the prior art,
The oxygen content of the coating is between 0.01% and 3.5%
, Which is one digit larger than in the present invention. The gas permeability of the prior art HVOF and HVAF coatings (corresponding to the penetration of the porous part) measured from 0.05 to 2.0 square nanometers, much 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 prior art HVOF and HVAF techniques.

[Brief description of the drawings]

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

FIG. 2 is a schematic longitudinal cross-sectional view of a high-speed thermal spray device having a catalyst member in the form of a wire mesh insert, the device comprising another catalyst having an annular shape about a first inner expansion nozzle. It has a burner and another nozzle.

FIG. 3 is a schematic longitudinal cross-sectional view of a high-speed thermal spray device having a coated catalyst member on a passage and a downstream surface of a catalytic ceramic support forming an internal burner. . The spray material is sprayed
The tip of two consumable wires, which are directed toward the axis of the expansion nozzle and are melted by an electric arc machine, are jetted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel supply tube 2 Powder injection device 3 Oxidant (or air) supply tube 5 Air distributor 6 Mixing block 8 Catalyst member 9 Gas assembly 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 Flammable 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 Section C Through hole D Cooling passage E Air hole F Mixing section G Mixture exit hole H Section I Particle flow J Substrate K Secondary section L Secondary mixing section M Combustion slot N Section

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Verstoke Andrew A. Virginia, USA 23112 Midlothian Waterford Way 1di 2704 F-term (reference) 3K023 JA02 JD01 3K065 SA01 4D075 AA06 AA86 BB16Y BB32Y BB34Y BB56Y BB57Y BB93Y DA06 DB01 4F033 QA01 QA08 QB02Y QB05 QB12Y QB13Y QB14Y QB19 QC02 QD02 QD03 QD14 QD15 QF15Y QG01 QG11 QG14 QG19 QG20 QH02 QH05 QH10 QK19X

Claims (2)

[Claims] 1. A high-speed thermal spray device for depositing a substance on a substrate, comprising: a mixing assembly designed to mix the oxidant gas and the fuel; An internal burner for combustion of the mixture; an igniter for initiating combustion of the mixture; a gas expansion nozzle configured to receive a product of combustion of the mixture and form a high velocity gas jet; A material delivery unit for delivering the spray material to the jet, and forming a stream of particles accelerated by the jet and heated below the melting point of the spray material, wherein the fuel is highly combustible. An inert gas is added to the oxidizing gas, and the oxidizing gas is controlled to a predetermined concentration range that does not cause misfire. Lowering the tempering temperature, a rapid thermal spray apparatus characterized by being configured to promote the prevention of oxidation of the welding material on the substrate. 2. A method of forming a coating or agglomerated material by depositing a material on a substrate in a high speed thermal spray device, the method comprising mixing a fuel with an oxidant gas of a mixing assembly. Igniting and burning a mixture of the oxidizer and fuel in an internal burner; forming a high velocity gas jet of the combustion product of the mixture in a gas expansion nozzle; being accelerated by the jet; Introducing a selected spray material into the jet by a material delivery unit to form a stream of particles that is heated below the melting point of the spray material, further comprising: An extremely flammable fuel, an inert gas is added to the oxidizing gas, and the concentration is controlled to a predetermined concentration range that does not cause misfire, Therefore, a method for forming a coating or a lump material characterized by lowering the combustion temperature and preventing oxidation of the deposited material on the substrate.