JPH06312149A - High-density oxygen coating by thermal spraying - Google Patents

Abstract

PURPOSE: To efficiently form a ceramic coating having a high density and high tacky adhesive force by disposing a nozzle member having an axial conduit constituted in such a manner that a plurality of orifices terminate at a nozzle face and are branched in a radial direction. CONSTITUTION: The nozzle member 54 is composed of an inner section 55 of the pipe and the outer section 56 of the pipe. The outer section 56 constitutes the annular orifice means on the outer side. The annular flow of a combustible mixture is injected into a combustion chamber 82 by this orifice means. The nozzle member 54 also has the axial conduit 62 extending forward of the pipe 33 for powder in a carrier gas. The axial conduit 62 constitutes a plurality of the orifices 65 which terminate at the nozzle face and are branched radially therefrom. The annular orifice 59 on the outer side for the combustible mixture or the plurality of orifices formed to an annular form are in proximity to the branched orifices 65 in order to allow the direct incorporation of the branched powder streams into the combustible mixture.

Description

Detailed Description of the Invention

[0001]

This invention relates to thermal spraying of oxide ceramics,
More particularly, it relates to a method and apparatus for producing a high density, tacky coating of oxide ceramics, and more particularly to aluminum oxide coatings useful in electrical insulation.

[0002]

2. Description of the Related Art Thermal spraying, also called flame spraying, is for melting a heat-fusible material such as metal or ceramic, or at least softening by heating, and promoting a softening substance as particles to a surface to be coated. Including that. The heated particles are rapidly cooled, and the heated particles further collide with the attached surface. A thermal spray gun used to heat and propel particles is disclosed in US Pat. No. 3,111,267 (Shepard et al.). In such a type of thermal spray gun, a heat-melting material such as metal or an oxide is supplied to the gun in a powder state. For such powders, US standard screen size from 100 mesh (149microns) to about 2micro
Small size particles between ns are typical. The heat for powder spraying is generally obtained from combustion flames or arc-generated plasma flames. The carrier gas for taking in and moving the powder may be one type of combustion gas, an inert gas such as nitrogen, or simply compressed air.

High speed spraying has been performed to produce high quality coatings on many types of spray materials. In many respects, plasma spraying is useful as a high speed process. However, since the powder is supplied in the transverse direction with respect to the high-velocity plasma flow, there is a risk of non-uniform heating and / or insufficient incorporation of particles.

A rocket type powder spray gun has recently become practical, one example of which is US Pat.
16, 421 (Browning). This type of gun has an internal combustion chamber adapted to allow high pressure combustion fluid to pass through long nozzles and open channels. The powder is supplied to this nozzle chamber and heated and propelled by the combustion fluid.

A short nozzle spraying device for high speed spraying is disclosed in US Pat. No. 4,865,252 (Rotoli;
co et al.). In this device, the combustion gas flows annularly and the powder is fed coaxially into the combustion chamber so that it is contained inside the flow. Air also flows in a ring,
This flow is coaxially injected outside the annular flow of combustion gas along the wall of the combustion chamber. A thermal spray stream with heated powder exits the open end of the combustion chamber.

In the device of the Rotorico patent, a further annular internal flow of compressed air is injected coaxially from the nozzle into the combustion chamber between the combustible mixture and the axial powder / carrier gas. The equipment based on the Rotolico patent has an axial powder feed and an annular internal flow that minimizes the material deposited inside the gas cap to produce high quality metal and carbide coatings. Extremely useful.

High velocity oxygen-f
uel (HVOF) spraying is particularly advantageous for high density coatings of metals and carbides with low oxygen content. This HVOF used for ceramic spraying is
Although some have been disclosed (e.g., U.S. Pat. No. 4,416,421, cited above), in actual high velocity combustion processes, refractory oxygen ceramic powder particles are either sufficiently melted or heat softened. However, the heating could not be performed satisfactorily. As a result, the deposition efficiency was low, and the coating quality could not be improved much compared to the conventional thermal spraying process.

Aluminum oxide (alumina) is typical of refractory oxides useful in thermal spray processes, such as producing electrically insulating coating layers. Plasma spraying with this oxide has also been done for high quality coatings of aluminum oxide, although there are some practical processes where low velocity combustion spraying is sufficient.
However, in this case, due to the rapid cooling of the sprayed particles on the substrate, the alpha phase of the alumina is reduced and the metastable gamma phase becomes predominant, eg 80 to 85% gamma, and such coatings provide insulation. The yield strength will be in the range of 12 to 20 volts / micron. Therefore, a coating with a higher stable alpha phase, that is, a coating with a higher dielectric strength is desired.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved spray gun for spraying oxide ceramic powders to produce high density, tacky ceramic coatings. . Yet another object is to provide an improved high velocity oxyfuel spray gun. Yet another object is to provide an improved method for producing high density, tacky oxide ceramic coatings, especially aluminum oxide coatings.
Yet another object is to provide a novel component comprising a metal substrate provided with a dense and tacky oxide ceramic coating, especially an aluminum oxide coating with increased alpha phase. In addition, it is also an object to provide an aluminum oxide coating with high dielectric breakdown strength. Other purposes will be apparent from the description that follows.

At least some of these and other objectives,
This is accomplished by a spray gun that includes a nozzle member. The nozzle member comprises an axial conduit used to move a powder stream of a heat fusible oxide ceramic in a carrier gas,
The axial conduit is configured with a plurality of radially divergent orifices ending at the nozzle face.
A gas cap extends from the nozzle member with one end open and the opposite end defining a combustion chamber secured by a nozzle face, the combustion chamber configured to receive a powder stream from a diverged orifice. Has been done. An annular stream of combustible mixture is injected coaxially into the combustion chamber from a nozzle member, proximate to and radially outward from the powder stream exiting the branched orifice. In this way, the combustion of the combustible mixture allows the powder stream to be incorporated directly into the combustible mixture. The compressed gas is ejected near the wall of the gas cap and radially outward of the annular flow of combustible mixture. Thereby, the ceramic-containing spray stream is propelled through the open ends.

The objects of the invention are also achieved by a method of using the spray gun of the invention.

The thermal spray gun comprises a nozzle member having an axial conduit configured to terminate in a nozzle face into a plurality of radially branched orifices, and an open end at one end. It includes a gas cap extending from a nozzle member that forms a combustion chamber whose end is fixed by the nozzle face. According to this method, first, the annular flow of the combustible mixture of combustion gas and oxygen is coaxially injected from the nozzle member into the combustion chamber, and the combustible mixture is burned in the combustion chamber. A powder stream of a heat fusible oxide ceramic in a carrier gas is passed through an orifice diverged from an axial conduit and is radially inwardly close to the annular stream of the combustible mixture so that the powder stream can be mixed directly into the combustion mixture. Then, move it to the combustion chamber. An annular outer flow of compressed, non-combustible gas is ejected radially outwardly of the annular flow of combustible mixture near the cylindrical wall surface, thereby propelling a thermal spray stream containing oxide ceramics through the open ends. . The thermal spray stream is directed toward the substrate, producing a dense, adherent oxide ceramic coating. Preferably, the pressure in the combustion chamber is increased by at least 2 bar above atmospheric pressure to eject an annular flow of the combustible mixture so that the thermal spray flow is sonic or supersonic.

The preferred oxide ceramic is a refractory oxide, most preferably aluminum oxide. Therefore, it is possible to manufacture a component including a metal substrate coated with a high-density and highly-adhesive oxide ceramic by the above-described method. The aluminum oxide coating contains at least 25% alpha phase and at least 2
The dielectric breakdown strength of 5 volts / micron is shown as a characteristic.

[0014]

DETAILED DESCRIPTION An example of an apparatus for practicing the present invention is depicted in FIG. The thermal spray gun 10 has a gas head 12 having a tube member mounted thereon as a gas cap 14, a valve portion 16 for supplying fuel, oxygen, and air to the gas head, and a handle 17. Valve part 16
Has a hose mount 18 for fuel gas, a hose mount 19 for oxygen, and a hose mount 20 for air. These three attachment parts are the fuel source 21,
It is connected to the oxygen source 22 and the air source 24, respectively. Each orifice 25 in the cylindrical valve 26 controls a respective gas from the mount to the gun. The valve and its associated components include a set of valve levers 27 and sealing means including a plunger 28 for each gas flow portion, a spring 29, and an O-ring 30.

A cylindrical siphon plug 31 is attached to a corresponding hollow portion of the gas head 12, and a plurality of O-rings 32 attached thereto maintain airtightness. The siphon plug is equipped with a tube 33 having a central passage 34. The siphon plug further has an annular groove 35 and another annular groove 36 therein with a plurality of internal connection passages 38 (two shown). Figure 1
When the cylindrical valve 26 is in the open position as shown in FIG.
And through the passageway 42 through the cylindrical valve 26 and from there to the annular groove 35 and the internal connection passageway 38. In a similar configuration, fuel gas flows from the fuel source 21 and hose 46 to its hose mount 18, cylindrical valve 26, and passage 4.
8 into the groove 36, is mixed with oxygen and flows as a combustible mixture into the annular groove 52 via a passage 50 which is in straight line with the passage 38. Due to the annular groove 52, this combustible mixture is supplied to the passages 53 arranged in a plurality of arches behind the nozzle member 54.

Referring to FIG. 2 for details, the nozzle member 54 includes an inner tube portion 55 and an outer tube portion 56.
Well organized. (The term "inside" as used in this description and claims refers to the one closer to the axis,
"Outside" refers to the side away from the axis. Also, "forward" or "forward" refers to the direction toward the open end of the gun, and "rearward" or "backward" refers to the opposite. The outer portion 56 defines outer annular orifice means by which the annular flow of combustible combustion mixture is injected into the combustion chamber. The orifice means has an annular opening 57 at the front.
It is preferable that the outer wall surface 58 of the inner portion is coupled to the radially inwardly facing side surface. Passage 5
The orifice system guided from 3 to the annular opening may be a plurality of arcuately spaced orifices or an annular orifice 59.

The combustible mixture flowing from the aligned annular grooves 52 thus creates an annular flow through one orifice (or multiple orifices or an annulus) 59 and ignites in the annular opening 57. The nozzle nut 60 supports the burner nozzle 54 and the siphon plug 31 on the gas head 12. In addition, 6 O-rings at 2 locations
1 is conventionally installed between the nozzle 54 and the siphon plug 31 to provide hermeticity. The burner nozzle 54 extends to the gas cap 14, which itself is supported in position by a threaded retainer ring 64 and extends forward from the nozzle.

The nozzle member 54 also includes an axial conduit 62 extending forward of the tube 33 for powder in the carrier gas. The axial conduit terminates at the nozzle face, as also shown in FIG. 3, and then becomes a plurality of radially branched orifices 65. In this embodiment, four (two of which are shown in FIG. 2)
It uses a branched orifice. The number of orifices is not strictly determined, but 2 to 8 is sufficient. The orifices are preferably arranged in an arch with an angle of 10 to 30 degrees, for example 23 degrees, with respect to the axis 63. An outer annular orifice 59 for the combustible mixture or a plurality of rings in order to allow the combustible mixture to be in close proximity to the powder stream exiting the branched orifice and to mix the branched powder stream directly into the combustible mixture. The orifices in the must be in close proximity to the branched orifices.

An oblique passage (not shown) extends rearwardly from the tube 33 to the powder connection 75. Therefore,
The carrier hose 66 and the central bore (axial conduit) 62 are adapted to receive powder from a powder feeder 67. The powder is entrained by a supply hose 66 into a carrier gas such as compressed air from a compressed gas source 68. The powder feeder 67 may be of conventional or suitable type as long as it can distribute the carrier gas at a sufficiently high pressure and provide it to the combustion chamber 82 within the gun 10.

Air or other non-combustible gas is supplied by the air source 24.
From the hose 69 through the hose mount 20, the cylindrical valve 26, and the passage 70 to the space 71 inside the retainer ring 64. The transverse opening 72 of the nozzle nut 60 is in communication with the space 71 by the cylindrical combustion chamber 82 in the gas cap 14, and air flows from the space 71 as an outer sheath through the transverse opening 72. It is like this. The air also has an annular slot 8 between the outer surface of the nozzle 54 and the cylindrical wall surface 86.
Pass 4. The cylindrical wall surface 86 faces inwardly to form the combustion chamber 82, and when it goes forward through the slot 84, it exits into the combustion chamber.
This flow exits the open channel at the open end 88 in the gas cap 14 through the combustion chamber 82 as an annular outer flow that also mixes with the inner flow. The combustion chamber 82 is fixed to the face 89 of the nozzle 54 at the rear end portion on the opposite side.

It is preferable that at least the outer end of the cylindrical wall surface 86 of the combustion chamber is inclined in a direction tapering forward from the nozzle at an angle with respect to the axis, and the angle is from 2 degrees to 1 degree.
Most preferably it is between 0 degrees, for example 5 degrees. Also at the slot 84, it is preferable that the cylindrical wall surface 86 of the combustion chamber be inclined forward from the nozzle at an angle with respect to the axis, and the angle is between 12 degrees and 16 degrees,
Most preferably, for example, 14.5 degrees. In addition, the slot 84 provides a sufficient distance for the annular air flow to be adequate, for example as long as the depth 102 of the combustion chamber.
The distance must be at least half the depth 102 or more.

Further, ventilation holes are arranged at the ignition position in the cylindrical valve 26, and air holes 90 are formed in the cylindrical valve 26.
There is so that air can flow for ignition. Further, in order to enable such ignition without causing flashback, the angle and distance described above are important factors. (Similar to the air hole 90, there is a vent hole for ignition of oxygen and fuel of the cylindrical valve 26, but not shown.) In the gas head 12, the diameter of the central hole (axial conduit) 62 is set to 2.0 mm. In this case, the distance (depth 102) from the nozzle face of the opening end 88 of the gas cap is 0.9.
It will be 5 cm. That is, the combustion chamber 82, which also takes in the powder, is relatively short, typically 1 to 2 times the diameter of the open end 88.

The supply of gas to each cylindrical combustion chamber is
It should be carried out at a sufficiently high pressure, for example at least 2 bar (30 psi) above atmospheric pressure. It is like a spark device and is conventionally ignited so that a mixture of combustion gas and air exits the open end as a powder-loaded sonic (choke) or supersonic stream. The heat of combustion heats or melts or at least heats and softens the powder material to deposit the coating on the substrate. At this time, shock wave brilliance is observed. Since this flow is under expansion, supersonic flow can be obtained without making the nozzle outlet of the expansion type.

The combustion gas may be propane, hydrogen or the like, but propylene gas or methylacetylene-
Propadiene (MPS) is preferred. With these preferred gases, fairly fast spray streams and excellent coatings can be achieved without flashback. For example, about 7 kg / cm ² gauge pressure (pressure expressed as the difference with atmospheric pressure as zero), propylene or MPS, 10 kg / cm
When oxygen was introduced at ² and air at 5.6 kg / cm ² into the gun, at least 8 shock wave radiances could be readily observed in the spray stream without powder flow.

The present invention generally has a particle size distribution of 1 to 30.
It is preferable to use a heat-fusible oxide ceramic powder of microns, more preferably a particle size distribution of 5 to 20 microns. Suitable spray oxides include aluminum oxide, titanium dioxide, and alumina-titania composites.

It is particularly preferable to use high-purity aluminum oxide (Al2O3). This thermal spray coating has a porosity of less than 0.25% as measured by the line intercept method, which is less than 15% alpha phase compared to conventional coatings, but at least 25% with this coating. Furthermore, such coatings have a breakdown strength of at least 28 volt.
Become s / micron. At lower dielectric breakdown strength, the coating, not only in this high-purity aluminum oxide, but also in other oxides, has a typical cross-sectional structure of HVOF coatings: laminated lens-shaped grains, i.e. It is melted and sprayed at a speed and becomes flat powder particles.

A specific mode will be described below.

2.5 to 3.2 kg / cm ² (35 to 45 ps
A planar copper substrate was produced by light grit blasting with 177 to 590 grit alumina at ig) atmospheric pressure. 99% with a particle size distribution of 20 to 5 microns
The high-purity aluminum oxide powder of 1. was sprayed by the above-mentioned suitable apparatus with reference to FIGS. 9.4kg / cm ² (1
3. 300 l / min (633 scfh) oxygen at 35 psig),
Combustion gas 5 kg / cm ² at (65psig) 97l / min (206scfh ) and 328L / mi at 5.2kg / cm ² (75psig),
n (694 scfh) of air was supplied respectively. A high pressure powder feeder is disclosed in the assignee of the present invention, US Pat.
No. 99, and was marketed by the Perkin-Elmer company as the DJB ™ powder feeder of the Metco ™ brand. With this feeder, 12 l / mi at 8.8 kg / cm ² (125 psig)
23gm / min powder with n (25scfh) nitrogen carrier
(3 lbs / hr) was supplied. The spraying distance was 13 cm and the moving speed was 4.5 m / min. The resulting coating was conventionally atomized to a thickness of 250 to 300 microns.

When analyzed by X-ray, the coating of the present invention, compared to a conventional plasma spray coating containing 20% alpha phase and 80% gamma phase, contained 35% alpha phase, 55% eta phase, and 7.4
% Beta phase.

Dielectric breakdown strength was measured by a conventional simple method. This conventional method involves contacting the electrodes with the coating surface and applying a voltage between the probe and the substrate.
Voltage was applied and increased until destruction occurred. This was repeated at 5 points on the surface. Fracture strength is typically 2 to 2 with respect to coating thickness
30 to 40 volts / micron compared to 0 volts / micron
Became within the range.

Although the present invention has been described in detail with reference to particular embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made within the spirit of the invention and the scope of the appended claims. Ah That is, the invention is limited only by the appended claims and the same content as the claims, and is not limited to the specific embodiments.

[0032]

EFFECT OF THE INVENTION There is no fear of insufficient intake of powder flow,
Since uniform and sufficient heating can be performed, high density and highly adherent ceramic coating can be efficiently performed.

High velocity oxygen-f
In the uel (HVOF) thermal spraying process, the powder particles can be heated sufficiently, resulting in higher deposition efficiency and improved coating quality compared to conventional processes.

In the coatings produced, including the case of plasma spraying with aluminum oxide (alumina), the proportion of the alpha phase is high and a high breakdown strength is obtained.

By devising the structure of the combustion chamber, it is possible to perform spraying without flashback.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a thermal spray gun of the present invention.

FIG. 2 is an enlarged view of a front end portion of FIG.

3 is a cross-sectional view taken along line 3-3 of FIG.

[Explanation of symbols]

10 spray gun, 12 gas head, 14 gas cap, 16 valve part, 17 handle, 1
8, 19, 20 Hose attachment part, 21 Fuel source,
22 oxygen source, 24 air source, 25 orifice,
26 cylindrical valve, 27 valve lever, 28
Plunger, 29 springs, 30 O-rings, 3
1 Siphon plug, 32 O-ring, 33
Pipe, 34 central passage, 35, 36 annular groove, 38
Internal connection passage, 40 hose, 42 passage, 46
Hose, 48 passage, 50 passage, 52 annular groove, 53 passage, 54 nozzle member, 55 pipe inner portion, 56 pipe outer portion, 57 annular opening portion, 58 outer wall surface, 59 annular orifice, 6
0 nozzle nut, 61 O-ring, 62 shaft conduit (center hole), 63 shaft, 64 retainer ring,
65 branched orifice, 66 supply hose, 6
7 powder feeder, 68 compressed gas source, 69 hose, 70 passage, 71 space, 72 transverse opening, 75 powder connection, 82 combustion chamber,
84 annular slot, 86 combustion chamber cylindrical wall surface, 8
8 open ends, 89 nozzle face, 90 air holes, 102 combustion chamber depth

Claims (24)

[Claims] 1. In a thermal spray gun for spraying oxide ceramic powder to produce a dense and cohesive ceramic coating: a nozzle face and an axial conduit, the axial conduit ending at the nozzle face and a radius. Nozzle member used to move the powder stream of the easily heated powder in the carrier gas, which is configured to have a plurality of orifices branched in a direction; The one end of the combustion chamber configured to face to is open and the opposite end is fixed by the nozzle face, and the combustion chamber is configured to receive the powder flow from the branched orifice. A gas cap extending from the nozzle member; a powder of an annular flow of a combustible mixture of combustion gas and oxygen exiting the nozzle member from the branched orifice. A combustible gas injection means, which is arranged in close proximity to the end stream and radially outwardly and coaxially injected into the combustion chamber so that the combustion of the combustible mixture allows the powder stream to enter directly into the combustible mixture; and An annular outer flow of compressed, non-combustible gas is injected radially outward relative to the flow of the combustible mixture near a cylindrical wall surface, whereby a spray stream containing ceramic is propelled through the open end. A thermal spray gun including outer gas injection means configured to: 2. The thermal spray gun according to claim 1, wherein the branched orifice is branched at an angle of 10 to 30 degrees with respect to the axis. 3. The thermal spray gun according to claim 1, wherein the plurality of radially branched orifices are 2 to 8. 4. The combustible gas injection means is configured such that, when injecting an annular flow of a combustible mixture, the pressure in the combustion chamber is at least 2 bar higher than atmospheric pressure so that the spray flow becomes sonic velocity or supersonic velocity. The thermal spray gun according to claim 1. 5. The thermal spray gun according to claim 1, wherein the combustion chamber is tapered forward. 6. The combustible gas injection means injects an annular flow of a combustible mixture from a circumferential position of a nozzle face into a combustion chamber, the circumference of the nozzle face being substantially the same diameter as the opening end of the combustion chamber. The thermal spray gun according to claim 5, wherein the thermal spray gun is configured so as to have a. 7. The thermal spray gun of claim 6 wherein said combustion chamber open end is axially spaced from the nozzle face by a minimum distance of substantially 1 to 2 times the diameter of its circumference. 8. A high-density and highly adhesive coating,
A nozzle member having a nozzle face and an axial conduit configured to form a plurality of radially branched orifices terminating at the nozzle face, and one end of which is open and the other end of which is the nozzle It has a cylindrical wall surface that faces the combustion chamber fixed by the face inward,
In a method of making using a spray gun that includes a gas cap extending from the nozzle member, first, an annular flow of a combustible mixture of combustion gas and oxygen is provided from the nozzle member.
Injecting coaxially into the combustion chamber, combusting a combustible mixture in the combustion chamber, a powder stream of heated soluble oxide ceramic in a carrier gas through an orifice branched from the axial conduit,
Moved into the combustion chamber, radially inward and close to the annular flow of the combustible mixture so that the powder stream could be mixed directly into the combustion mixture, and secondly, an annular outer flow of compressed non-combustion gas into a cylinder. Spraying the flammable mixture radially outwardly near a wall surface causes a thermal spray stream containing oxide ceramics to be propelled through the open end, and the thermal spray stream to a substrate. A method for producing a high-density and high-adhesion coating, which comprises producing a high-density and high-adhesion oxide ceramic coating. 9. The method according to claim 8, wherein the branched orifice branches at an angle of 10 to 30 degrees with respect to the axis. 10. The method of claim 8 wherein the plurality of radially branched orifices is 2-8. 11. The first injecting step comprises injecting an annular flow of combustible mixture into a combustion chamber from a circumferential position of a nozzle face having a diameter substantially the same as the combustion chamber open end. 9. The method of claim 8 including. 12. The method of claim 11, wherein the combustion chamber open end is located axially from the nozzle face by a minimum distance of substantially 1 to 2 times the diameter of its circumference. 13. The first injection step includes the step of making the pressure in the combustion chamber at least 2 bar higher than the atmospheric pressure to inject an annular flow of a combustible mixture so that the spray flow becomes sonic velocity or supersonic velocity. The method of claim 8. 14. The method of claim 13, wherein the oxide ceramic predominantly comprises aluminum oxide. 15. The method of claim 14, wherein the oxide ceramic comprises high purity aluminum oxide. 16. The method of claim 15 wherein said aluminum oxide is used in the form of powder particles having a particle size of approximately 1 to 30 microns. 17. A nozzle member comprising a nozzle face and an axial conduit configured to result in a plurality of radially branched orifices terminating at the nozzle face, and one end of which is open and opposite. Using a spray gun that has a cylindrical wall surface whose end faces a combustion chamber fixed by the nozzle face facing inward and includes a gas cap extended from the nozzle member, An annular stream of a combustible mixture of oxygen is coaxially injected from the nozzle member into the combustion chamber, the combustible mixture is combusted in the combustion chamber, and a powder stream of heated fusible oxide ceramic in a carrier gas is branched into an axial conduit. Through the controlled orifice, radially inward of and close to the annular flow of the combustible mixture so that the powder flow can be mixed directly into the combustion mixture, and secondly, compressed. An annular outer flow of the stored non-combustible gas radially outwardly with respect to the flow of the combustible mixture in the vicinity of the cylindrical wall surface, whereby a thermal spray stream containing oxide ceramics is propelled through the open end. And a high-density, high-adhesion coating produced by a coating manufacturing method comprising directing the thermal spray flow toward a substrate to produce a high-density, high-adhesion oxide ceramic coating. Components that include metal substrates. 18. A component according to claim 17, characterized by the cross-sectional structure of lens-shaped particles having said coating laminated thereto. 19. The component of claim 18, wherein the oxide ceramic predominantly comprises aluminum oxide. 20. The component of claim 19, wherein the oxide ceramic comprises high purity aluminum oxide. 21. The aluminum oxide is at least 3
21. The component of claim 20, which contains 0% alpha phase. 22. The coating is at least 25 vo
22. The component according to claim 21, which has characteristics in dielectric breakdown strength of lts / micron. 23. A component comprising a metal substrate provided with a dense and adherent aluminum oxide coating, wherein the aluminum oxide comprises at least 25% alpha phase and the coating comprises laminated lens-shaped particles. A part characterized by showing characteristics in cross-section. 24. The coating has at least 25 volts /
24. The component of claim 23, further characterized by a dielectric breakdown strength of micron.