HVAF spray gun structure suitable for stable spraying of iron-based amorphous coating

Abstract

The invention discloses an HVAF spray gun structure suitable for stable spraying of an iron-based amorphous coating. The HVAF spray gun structure comprises a gun barrel cooling sleeve, a gun barrel, an air cavity sleeve, a combustion chamber, a gun body shell, a lengthened fixing sleeve, a fixing support, an isolation piece, a fuel gas mixer, a powder feeding needle fixing nut, a fuel gas dispersion isolator, a rear cover and a powder feeding needle fixing mandrel. And the powder feeding needle and the fuel gas mixing chamber are lengthened. The technical problem that when an existing HVAF spray gun sprays iron-based amorphous powder, the iron-based amorphous powder is prone to being stuck to a gun barrel or a combustion chamber is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal spraying, and in particular relates to an HVAF spray gun structure suitable for stable spraying of iron-based amorphous coatings. Background Art

[0002] Iron-based amorphous materials have a single disordered amorphous structure, without crystal defects such as dislocations and grain boundaries. Therefore, iron-based amorphous coatings have good corrosion resistance. At the same time, iron-based amorphous has extremely high hardness and strength, and its aging performance and impact resistance and high temperature resistance are outstanding. It is expected to replace traditional resin-based anti-skid coatings and be used as wear-resistant and anti-skid coatings for large ships.

[0003] The preparation processes of iron-based amorphous coatings include atmospheric plasma spraying (APS), arc spraying (AS) and supersonic flame spraying (HVAF and HVOF). Among them, the iron-based amorphous coatings prepared by HVAF spraying have the best basic properties such as amorphous content, oxygen content, porosity and bonding strength, and show the best wear resistance and corrosion resistance, and have great application potential. However, due to the low melting point of iron-based amorphous, the particles melt in the combustion chamber and the nozzle, and the viscosity is relatively large. Some of the molten particles will collide with the inner wall of the combustion chamber and the nozzle, and then adhere to the tube wall, causing a decrease in deposition efficiency and spray gun failure. At present, the mainstream HVAF spray guns on the market, such as Kermetico's AK7 spray gun and Uniquecoat's M3 and M2 spray guns, have obvious gun blocking phenomena when spraying iron-based amorphous powder continuously for half an hour, which limits their application in actual industrial production. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, to provide an HVAF spray gun structure suitable for stable spraying of iron-based amorphous coatings, and to solve the technical problem that the existing HVAF spray gun is prone to sticking to the gun barrel or combustion chamber when spraying iron-based amorphous powder.

[0005] The object of the present invention is achieved through the following technical scheme: A HVAF spray gun structure suitable for stable spraying of iron-based amorphous coatings comprises: a barrel cooling sleeve, a barrel, an air chamber sleeve, a combustion chamber, a gun body shell, an extended fixed sleeve, a fixed bracket, a spacer, a gas mixer, a powder feed needle fixing nut, a gas dispersion isolator, a rear cover, a powder feed needle fixing core shaft, an extended powder feed needle and a gas mixing chamber; wherein the tail of the barrel is fixed to the front end of the combustion chamber; the spacer is located at the rear end inside the combustion chamber; the gas mixer is assembled at the rear end of the combustion chamber; the gas dispersion isolator is fixed to the rear end of the gas mixer, and the rear cover presses the gas dispersion isolator; a gas mixing chamber is formed between the gas mixer and the gas dispersion isolator; the rear cover is connected to the gun body shell; the The long powder feeding needle passes through the center hole of the rear cover, the center hole of the gas dispersion isolator, the center hole of the gas mixer and the center hole of the isolation plate in sequence and extends to the middle of the combustion chamber; the tail of the extended powder feeding needle is fixed to the rear end of the gun body shell; the middle part of the extended powder feeding needle is fixed to the inner cavity of the gas mixer through the powder feeding needle fixing nut; the front end of the extended powder feeding needle is connected to the fixed bracket, and the extended fixed sleeve is sleeved on the outer surface of the fixed bracket, and the extended fixed sleeve covers the front end of the extended powder feeding needle; the powder feeding needle fixing core shaft is sleeved on the outer surface of the extended powder feeding needle, and the outer periphery of the powder feeding needle fixing core shaft is respectively connected to the rear cover and the gas mixer; the front end of the gun body shell is connected to the air chamber sleeve; the front end of the air chamber sleeve is connected to the barrel cooling sleeve.

[0006] The above-mentioned HVAF spray gun structure suitable for stable spraying of iron-based amorphous coatings also includes: a nozzle fixing screw, an M screw hole, and a clamping gasket; wherein the tail of the gun barrel is fixed to the front end of the combustion chamber by the nozzle fixing screw and the clamping gasket; the nozzle fixing screw cooperates with the M screw hole opened at the front end of the combustion chamber.

[0007] The HVAF spray gun structure suitable for stable spraying of iron-based amorphous coatings further comprises: a rear cover locking screw ring; wherein the rear cover and the gun body shell are connected by the rear cover locking screw ring.

[0008] The above-mentioned HVAF spray gun structure suitable for stable spraying of iron-based amorphous coatings also includes: a rear cover clamping nut and a powder feeding needle locking nut; wherein the tail of the extended powder feeding needle is fixed to the rear end of the gun body shell through the rear cover clamping nut and the powder feeding needle locking nut.

[0009] The HVAF spray gun structure suitable for stable spraying of iron-based amorphous coatings also includes: a casing locking screw; wherein the front end of the gun body shell is connected to the air chamber casing through the casing locking screw.

[0010] In the above HVAF spray gun structure suitable for stable spraying of iron-based amorphous coatings, the M thread at the rear end of the extended powder feeding needle is connected to the powder feeding pipe.

[0011] In the above-mentioned HVAF spray gun structure suitable for stable spraying of iron-based amorphous coatings, the rear cover is provided with a gas input interface; the gas dispersion isolator is provided with a first small hole; the side wall of the gas mixer is provided with an air input hole, and the front end of the gas mixer is provided with a second small hole; the isolation plate is provided with a third small hole; the side wall of the air chamber sleeve is provided with a main gas air interface; the gun body shell, air chamber sleeve and barrel cooling sleeve as a whole form an air cooling channel with the gap between the gun barrel, combustion chamber, gas mixer, gas dispersion isolator and rear cover as a whole; the rear cover is provided with a vertical powder feeding needle cooling air channel; the air cooling channel is respectively connected to the powder feeding needle cooling air channel and the air input hole; the front end of the barrel cooling sleeve is provided with a fourth small hole.

[0012] In the above-mentioned HVAF spray gun structure suitable for stable spraying of iron-based amorphous coatings, the combustion gas enters from the gas input interface on the rear cover, enters the gas mixing chamber through the first small hole on the gas dispersion isolator, and is evenly mixed with the air entering from the air input hole on the gas mixer, and then enters the rear end of the combustion chamber through the second small hole at the front end of the gas mixer, and is finally smoothly transmitted to the inner cavity of the combustion chamber through the third small hole evenly distributed on the isolation plate. After combustion, the combustion gas and air enter the gun barrel and are finally sprayed onto the surface of the substrate; compressed air is injected from the main gas air interface on the air chamber sleeve and fills the air cooling channel. A part of the compressed air cools the gun barrel and the combustion chamber, and is discharged from the fourth small hole distributed at the front end of the gun barrel cooling sleeve; a part of the compressed air enters the air input hole as a combustion-supporting gas; another part of the compressed air enters the outer cavity of the extended powder feeding needle from the powder feeding needle cooling air channel to cool the extended powder feeding needle.

[0013] In the above-mentioned HVAF spray gun structure suitable for stable spraying of iron-based amorphous coatings, there is an ignition system; wherein, the ignition system is arranged on the spark plug fixing screw hole in the middle of the combustion chamber.

[0014] In the HVAF spray gun structure suitable for stable spraying of iron-based amorphous coatings, the main gas in the combustion gas is propane, propylene or a mixture of the two, and the auxiliary gas is hydrogen; nitrogen is used as the powder feeding gas and is injected from the rear end of the extended powder feeding needle.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) The present invention solves the technical problem that the existing HVAF spray gun is easy to stick to the gun barrel or combustion chamber when spraying iron-based amorphous powder; through the design of the spray gun structure system, gun barrel optimization, powder feeding needle size extension and sleeve spraying thermal barrier coating and other technical approaches, an HVAF spray gun suitable for long-term stable spraying of iron-based amorphous coatings is prepared, which is simple to load and unload and has low maintenance cost. The sprayed coating has a high degree of amorphousness, good density and corrosion resistance, and achieves multiple functions such as wear resistance, anti-skid, and anti-corrosion;

[0017] (2) The barrel length of the present invention is relatively short (120 mm, while the conventional barrel length is more than 200 mm), so the HVAF jet velocity is relatively low and the temperature is relatively high, which is suitable for the spraying of Fe-based amorphous powders;

[0018] (3) The present invention lengthens the powder feeding needle and extends it to the middle of the combustion chamber, which is more in line with the aerodynamic environment at the front end of the combustion chamber and can effectively avoid the adhesion and agglomeration of powder at the outlet of the combustion chamber;

[0019] (4) Since the melting point of iron-based amorphous powder is relatively low, after the powder feeding needle of the present invention is lengthened, the residence time of the powder in the combustion chamber is shortened, the particles will not be over-melted, and a coating with an amorphous content exceeding 90% can be prepared;

[0020] (5) The powder delivery needle of the present invention is provided with an extended fixed sleeve sprayed with a thermal barrier coating, so that it can be used for a long time without burning even in a high temperature environment of the combustion chamber exceeding 2000°C;

[0021] (6) The present invention continuously sprays Fe-based amorphous powder for more than 5 hours, and the parts of the spray gun are not adhered or obviously burned. The density obtained by spraying reaches more than 99%. At the same time, the coating has no obvious rust after experiencing 1000 hours of neutral salt spray corrosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0023] Figure 1 It is a schematic diagram of the HVAF spray gun structure suitable for stable spraying of iron-based amorphous coatings provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to be able to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0025] Figure 1 Schematic diagram of the HVAF spray gun structure suitable for stable spraying of iron-based amorphous coatings provided by an embodiment of the present invention. Figure 1 As shown, the HVAF spray gun structure suitable for stable spraying of iron-based amorphous coatings includes: a barrel cooling sleeve 1, a barrel 2, an air chamber sleeve 3, a sleeve locking screw 5, a nozzle fixing screw 6, an M6 screw hole 7, a compression gasket 8, a combustion chamber 9, a gun body shell 10, an extended fixed sleeve 12, a fixed bracket 13, a spacer 14, a gas mixer 15, a powder needle fixing nut 16, a gas dispersion isolator 18, a rear cover 19, a rear cover locking screw 20, an M10 thread 21, a powder needle fixing mandrel 22, an extended powder needle 23, a rear cover compression nut 24, a powder needle locking nut 25 and a gas mixing chamber 26. Among them,

[0026] The tail of the gun barrel 2 is fixed to the front end of the combustion chamber 9 by means of a nozzle fixing screw 6 and a compression gasket 8; the nozzle fixing screw 6 is matched with an M6 screw hole 7 opened at the front end of the combustion chamber 9; the isolation plate 14 is located at the rear end of the combustion chamber 9; the gas mixer 15 is assembled at the rear end of the combustion chamber 9;

[0027] The gas dispersion isolator 18 is fixed to the rear end of the gas mixer 15, and the rear cover 19 presses the gas dispersion isolator 18; a gas mixing chamber 26 is formed between the gas mixer 15 and the gas dispersion isolator 18; the rear cover 19 is connected to the gun body shell 10 by a rear cover locking screw 20; the extended powder feeding needle 23 passes through the center hole of the rear cover 19, the center hole of the gas dispersion isolator 18, the center hole of the gas mixer 15 and the center hole of the isolation plate 14 in sequence and extends to the middle of the combustion chamber 9; the tail of the extended powder feeding needle 23 is fixed to the rear end of the gun body shell 10 by the rear cover clamping nut 24 and the powder feeding needle locking nut 25; the middle part of the extended powder feeding needle 23 passes through the powder feeding needle 23. The needle fixing nut 16 is fixed to the inner cavity of the gas mixer 15; the front end of the extended powder feeding needle 23 is connected to the fixed bracket 13, the extended fixed sleeve 12 is sleeved on the outer surface of the fixed bracket 13, and the extended fixed sleeve 12 covers the front end of the extended powder feeding needle 23; the powder feeding needle fixed core shaft 22 is sleeved on the outer surface of the extended powder feeding needle 23, and the outer periphery of the powder feeding needle fixed core shaft 22 is respectively connected to the rear cover 19 and the gas mixer 15; the front end of the gun body shell 10 is connected to the air chamber sleeve 3 through the sleeve locking screw ring 5; the front end of the air chamber sleeve 3 is connected to the barrel cooling sleeve 1; the M10 thread 21 at the rear end of the extended powder feeding needle 23 is connected to the powder feeding pipe.

[0028] The rear cover 19 is provided with a gas input interface 27; the gas dispersion isolator 18 is provided with a first small hole; the side wall of the gas mixer 15 is provided with an air input hole 17, and the front end of the gas mixer 15 is provided with a second small hole; the isolation plate 14 is provided with a third small hole; the side wall of the air chamber sleeve 3 is provided with a main gas air interface 4; the gun body shell 10, the air chamber sleeve 3 and the barrel cooling sleeve 1 as a whole form an air cooling channel 29 with the gap between the gun barrel 2, the combustion chamber 9, the gas mixer 15, the gas dispersion isolator 18 and the rear cover 19 as a whole; the rear cover 19 is provided with a vertical powder feeding needle cooling air channel 28; the air cooling channel 29 is respectively connected with the powder feeding needle cooling air channel 28 and the air input hole 17; the front end of the barrel cooling sleeve 1 is provided with a fourth small hole.

[0029] The combustion gas enters from the gas input interface 27 on the rear cover 19, and enters the gas mixing chamber 26 through the first small hole on the gas dispersion isolator 18, and is evenly mixed with the air entering from the air input hole 17 on the gas mixer 15, and then enters the rear end of the combustion chamber 9 through the second small hole at the front end of the gas mixer 15, and finally is smoothly transmitted to the inner cavity of the combustion chamber 9 through the third small holes evenly distributed on the isolation plate 14, and the combustion gas and air enter the gun barrel after combustion, and finally are sprayed onto the surface of the substrate;

[0030] Compressed air is injected through the main air interface 4 on the air chamber sleeve 3 and fills the air cooling channel 29. A part of the compressed air cools the barrel 2 and the combustion chamber 9 and is discharged from the fourth small hole distributed at the front end of the barrel cooling sleeve 1; a part of the compressed air enters the air input hole 17 as a combustion-supporting gas; another part of the compressed air enters the outer cavity of the extended powder feeding needle 23 through the powder feeding needle cooling air channel 28 to cool the extended powder feeding needle 23.

[0031] The gun barrel 2 is located at the front end of the spray gun, and the tail of the gun barrel 2 is fixed to the front end of the combustion chamber 9 by the nozzle fixing screw 6 and the clamping gasket 8. The nozzle fixing screw 6 cooperates with the four M6 screw holes 7 at the front end of the nozzle; the isolation plate 14 is located at the rear end inside the combustion chamber 9; the gas mixer 15 is assembled at the rear end of the combustion chamber 9 to clamp the isolation plate 14; the gas dispersion isolator 18 is fixed to the rear end of the gas mixer 15 and is clamped with the rear cover 19; the rear cover 19 is connected to the gun body shell 10 with the rear cover locking screw ring 20; the extended powder feeding needle 23 passes through the center hole of the rear cover 19, the gas dispersion isolator 18, the gas mixer 15, and the isolation plate 14 in turn, and extends to the middle of the combustion chamber 9, the tail of the extended powder feeding needle 23 is fixed to the rear end of the gun body shell 10 by the rear cover clamping nut 24 and the powder feeding needle locking nut 25, and the middle position of the extended powder feeding needle 23 is fixed to the inner cavity of the gas mixer 15 by the powder feeding needle fixing nut 16 , the front end is supported by a fixed bracket 13 to support the extended fixed sleeve 12. In order to ensure concentricity, a powder feeding needle fixed core shaft 22 is placed between the rear cover 19, the gas dispersion isolator 18, the gas mixer 15 and the extended powder feeding needle 23; the front end of the gun body shell 10 is fixed to the air chamber sleeve 3 by a sleeve locking screw ring 5, and the front end of the air chamber sleeve 3 is connected to the barrel cooling sleeve 1 by a threaded connection. The front end of the barrel cooling sleeve 1 is flush with the front end of the barrel 2, and there is a small assembly gap in the radial direction; the barrel 2 adopts a steel Laval tube with a length of only 120mm, which has the advantage of reducing the powder sticking to the nozzle; the powder feeding needle 23 is lengthened and extended to the middle of the combustion chamber 9, and a thermal barrier coating is sprayed on the extended fixed sleeve 12 at the end. The advantage is that the extended fixed sleeve 12 can protect the powder feeding needle from high-temperature ablation in the combustion chamber, and the thermal barrier coating on the surface can significantly reduce the extended fixed sleeve 12, thereby improving the working stability.

[0032] The combustion gas (usually the main gas is propane, propylene or a mixture of the two, and the auxiliary gas is hydrogen) enters from the gas input interface 27 on the rear cover 19, and enters the gas mixing chamber 26 through the first small hole on the gas dispersion isolator 18, and is evenly mixed with the air (combustion-supporting gas) entering from the air input hole 17 on the gas mixer 15, and then enters the rear end of the combustion chamber 9 through the second small hole at the front end of the gas mixer 15, and is finally smoothly transmitted to the inner cavity of the combustion chamber 9 through the third small holes evenly distributed on the isolation plate 14. After the combustion gas and air are burned, they enter the gun barrel and are finally sprayed onto the surface of the substrate; compressed air is injected from the main gas air interface 4 on the air chamber sleeve 3 and fills the air cooling channel 29. The air cooling channel 29 is formed by the gap between the gun body shell 10, the air chamber sleeve 3, the barrel cooling sleeve 1, the gun barrel 2, the combustion chamber 9, the gas mixer 15, the gas dispersion isolator 18 and the rear cover 19. A part of the compressed air cools the gun barrel 2 and the combustion chamber 9, and is discharged from the fourth small hole distributed at the front end of the gun barrel cooling sleeve 1. A part of the compressed air enters the air input hole 17 as a combustion-supporting gas as mentioned above, and the other part enters the outer cavity of the extended powder feeding needle 23 through the powder feeding needle cooling air channel 28 as a powder feeding needle cooling gas; nitrogen is used as the powder feeding gas, and is injected from the rear end of the extended powder feeding needle 23 carrying Fe-based spray powder, and the powder feeding pipe is connected to the M10 thread 21 at the rear end of the extended powder feeding needle 23. After continuous spraying of Fe-based amorphous powder for more than 5 hours, there is no obvious adhesion between the barrel 2 and the inner wall of the combustion chamber 9, and there is no burning of the extended powder feeding needle 23 and the extended fixed sleeve 12. The amorphous content of the sprayed coating is more than 90%, and the density reaches more than 99%. At the same time, the coating has no obvious rust after experiencing 1000 hours of neutral salt spray corrosion.

[0033] The HVAF spray gun structure suitable for stable spraying of iron-based amorphous coatings also includes: an ignition system; wherein the ignition system is arranged on the spark plug fixing screw hole 11 in the middle of the combustion chamber 9. The ignition system is composed of an ignition coil and a spark plug, and can realize pulse ignition. The spark plug is fixed on the spark plug fixing screw hole 11 in the middle of the combustion chamber 9.

[0034] The locking and fixing device is basically connected by threads, and the screws and nuts used are all implemented in accordance with national standards; the mating surfaces of the extended powder feeding needle 23, the rear cover 19, the gas dispersion isolator 18, the gas mixer 15, etc. are sealed with O-rings; the equipment is easy and quick to load and unload, and the cost of replacing accessories is low.

[0035] Compressed air enters the spray gun through the main air interface 4, and the gas enters the spray gun through the gas input interface 27. After being fully mixed and evenly distributed through the gas dispersion isolator 18 and the densely arranged small holes on the gas mixer 15, it enters the combustion chamber 9. The spark plug installed on the spark plug fixing screw hole 11 discharges pulses under program control, ignites the mixed gas in the combustion chamber 9, and forms a high-pressure and high-speed flame, which is accelerated by the Laval gun barrel 2 and sprayed onto the workpiece to be sprayed. During spraying, the combustion chamber, the gun barrel, and the extended powder feeding needle will face a large heat flow scour, and the compressed air will flow at high speed through the air cooling channel 29 to take away the heat, thereby maintaining a low temperature.

[0036] The present embodiment solves the technical problem that the existing HVAF spray gun is easy to stick to the gun barrel or combustion chamber when spraying iron-based amorphous powder; through the design of the spray gun structure system, gun barrel optimization, extension of the powder feeding needle size and sleeve spraying thermal barrier coating and other technical approaches, an HVAF spray gun suitable for long-term stable spraying of iron-based amorphous coatings with simple loading and unloading and low maintenance cost is prepared, and the coating obtained by spraying has a high degree of amorphousness, good density and corrosion resistance, and achieves multiple functions such as wear resistance, anti-skid and anti-corrosion; the barrel length of the present embodiment is relatively short (120mm, the conventional barrel length reaches more than 200mm), so the HVAF jet velocity is relatively low and the temperature is relatively high, which is suitable for the spraying of Fe-based amorphous powders; the powder feeding needle is lengthened in the present embodiment, It extends to the middle of the combustion chamber, which is more in line with the aerodynamic environment at the front end of the combustion chamber, and can effectively avoid the adhesion and agglomeration of the powder at the outlet of the combustion chamber; due to the low melting point of the iron-based amorphous powder, after the powder feeding needle of this embodiment is lengthened, the residence time of the powder in the combustion chamber is shortened, the particles will not be over-melted, and a coating with an amorphous content of more than 90% can be prepared; the powder feeding needle of this embodiment is added with an extended fixed sleeve sprayed with a thermal barrier coating on the outside, although it is in a high temperature environment of the combustion chamber exceeding 2000°C, it can be used for a long time without burning; this embodiment continuously sprays the Fe-based amorphous powder for more than 5 hours, and the various parts of the spray gun have no adhesion or obvious burning, and the density obtained by spraying reaches more than 99%. At the same time, the coating has no obvious rust after experiencing 1000 hours of neutral salt spray corrosion.

[0037] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A HVAF spray gun structure suitable for stable spraying of iron-based amorphous coatings, characterized in that include: A gun barrel cooling sleeve (1), a gun barrel (2), an air chamber sleeve (3), a combustion chamber (9), a gun body shell (10), an extended fixed sleeve (12), a fixed bracket (13), a spacer (14), a gas mixer (15), a powder delivery needle fixing nut (16), a gas dispersion spacer (18), a rear cover (19), a powder delivery needle fixing mandrel (22), an extended powder delivery needle (23) and a gas mixing chamber (26); wherein, The rear end of the gun barrel (2) is fixed to the front end of the combustion chamber (9); The isolation plate (14) is located at the rear end of the combustion chamber (9); The gas mixer (15) is mounted at the rear end of the combustion chamber (9); The gas dispersion isolator (18) is fixed to the rear end of the gas mixer (15), and the rear cover (19) presses the gas dispersion isolator (18); a gas mixing chamber (26) is formed between the gas mixer (15) and the gas dispersion isolator (18); The rear cover (19) is connected to the gun body shell (10); The extended powder feeding needle (23) sequentially passes through the central hole of the rear cover (19), the central hole of the gas dispersion isolator (18), the central hole of the gas mixer (15) and the central hole of the isolation plate (14) and extends to the middle of the combustion chamber (9); The tail of the extended powder feeding needle (23) is fixed to the rear end of the gun body shell (10); The middle part of the extended powder feeding needle (23) is fixed to the inner cavity of the gas mixer (15) through a powder feeding needle fixing nut (16); The front end of the extended powder feeding needle (23) is connected to the fixed bracket (13), the extended fixed sleeve (12) is sleeved on the outer surface of the fixed bracket (13), and the extended fixed sleeve (12) covers the front end of the extended powder feeding needle (23); The powder feeding needle fixed core shaft (22) is sleeved on the outer surface of the extended powder feeding needle (23), and the outer periphery of the powder feeding needle fixed core shaft (22) is respectively connected to the rear cover (19) and the gas mixer (15); The front end of the gun body shell (10) is connected to the air chamber sleeve (3); The front end of the air chamber sleeve (3) is connected to the barrel cooling sleeve (1).

2. The HVAF spray gun structure suitable for stable spraying of iron-based amorphous coating according to claim 1 is characterized in that Also includes: Nozzle fixing screw (6), M6 screw hole (7), and compression gasket (8); wherein, The rear end of the gun barrel (2) is fixed to the front end of the combustion chamber (9) via a nozzle fixing screw (6) and a compression gasket (8); The nozzle fixing screw (6) cooperates with an M6 screw hole (7) provided at the front end of the combustion chamber (9).

3. The HVAF spray gun structure suitable for stable spraying of iron-based amorphous coating according to claim 1 is characterized in that It also includes: a rear cover locking screw ring (20); wherein, The rear cover (19) is connected to the gun body shell (10) by a rear cover locking screw ring (20).

4. The HVAF spray gun structure suitable for stable spraying of iron-based amorphous coating according to claim 1, characterized in that It also includes: a rear cover clamping nut (24) and a powder feeding needle locking nut (25); wherein, The tail of the extended powder feeding needle (23) is fixed to the rear end of the gun body housing (10) through a rear cover clamping nut (24) and a powder feeding needle locking nut (25).

5. The HVAF spray gun structure suitable for stable spraying of iron-based amorphous coating according to claim 1, characterized in that It also includes: a casing locking screw ring (5); wherein, The front end of the gun body shell (10) is connected to the air chamber sleeve (3) via the sleeve locking screw ring (5).

6. The HVAF spray gun structure suitable for stable spraying of iron-based amorphous coating according to claim 1, characterized in that: The M10 thread (21) at the rear end of the extended powder feeding needle (23) is connected to the powder feeding pipe.

7. The HVAF spray gun structure suitable for stable spraying of iron-based amorphous coating according to claim 1, characterized in that: The rear cover (19) is provided with a gas input interface (27); The gas dispersion isolator (18) is provided with a first small hole; An air input hole (17) is provided on the side wall of the gas mixer (15), and a second small hole is provided on the front end of the gas mixer (15); The isolation sheet (14) is provided with a third small hole; The side wall of the air chamber sleeve (3) is provided with a main air interface (4); The gap between the gun body shell (10), the air chamber sleeve (3) and the gun barrel cooling sleeve (1) as a whole and the gun barrel (2), the combustion chamber (9), the gas mixer (15), the gas dispersion isolator (18) and the rear cover (19) as a whole forms an air cooling channel (29); The rear cover (19) is provided with a vertical powder feeding needle cooling air channel (28); the air cooling channel (29) is respectively connected to the powder feeding needle cooling air channel (28) and the air input hole (17); A fourth small hole is provided at the front end of the barrel cooling sleeve (1).

8. The HVAF spray gun structure suitable for stable spraying of iron-based amorphous coating according to claim 7, characterized in that: The combustion gas enters through the gas input interface (27) on the rear cover (19), enters the gas mixing chamber (26) through the first small hole on the gas dispersion isolator (18), and is evenly mixed with the air entering through the air input hole (17) on the gas mixer (15), then enters the rear end of the combustion chamber (9) through the second small hole at the front end of the gas mixer (15), and finally is smoothly transmitted to the inner cavity of the combustion chamber (9) through the third small holes evenly distributed on the isolation plate (14). After the combustion gas and air are burned, they enter the gun barrel and are finally sprayed onto the surface of the substrate; Compressed air is injected from the main air interface (4) on the air chamber sleeve (3) and fills the air cooling channel (29). A part of the compressed air cools the gun barrel (2) and the combustion chamber (9) and is discharged from the fourth small hole distributed at the front end of the gun barrel cooling sleeve (1); a part of the compressed air enters the air input hole (17) as a combustion-supporting gas; and another part of the compressed air enters the outer cavity of the extended powder feeding needle (23) through the powder feeding needle cooling air channel (28) to cool the extended powder feeding needle (23).

9. The HVAF spray gun structure suitable for stable spraying of iron-based amorphous coating according to claim 1, characterized in that It also includes: an ignition system; wherein the ignition system is arranged on a spark plug fixing screw hole (11) in the middle of the combustion chamber (9).

10. The HVAF spray gun structure suitable for stable spraying of iron-based amorphous coating according to claim 8, characterized in that: In the combustion gas, the main gas is propane, propylene or a mixture of the two, and the auxiliary gas is hydrogen; nitrogen is used as powder feeding gas and is injected from the rear end of the extended powder feeding needle (23).

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