JP5576540B2 - Fine powder ceramics impact sintering coating method - Google Patents

Description

  The present invention relates to an impact sintering coating method using a ceramic film and fine powder having functions such as heat resistance, heat transfer, electrical insulation, and corrosion resistance.

  Metals / alloys and ceramics change their properties due to changes in temperature. In a surface modification process where the treatment temperature is high, the material properties at room temperature are transformed by the high temperature treatment and changed to other properties. In particular, in the conventional thermal spraying process, it is difficult to perform thermal spraying at a temperature below 4000 ° C to 30000 ° C and gas thermal spraying method 2200 ° C to 3400 ° C in plasma spraying by electric spraying. There is a strong demand for a method in which coating is performed by changing the coating composition by controlling accurately at a low temperature at which the material does not transform. In addition, when the thermal spraying powder is 10 μm or less, particularly 5 μm or less, a normal powder supply apparatus cannot be stably supplied because it is intermittently supplied or causes a bridge and clogs the passage.

Japanese Unexamined Patent Publication No. 10-60617 Flame temperature 2200 to 3400 ° C, powder supplied from inside JP 2006-108178 Al2O3 particle plasma sprayed unmelted Flat ratio of molten particles in coating by plasma spraying method and ultra-high speed flame spraying method Patent application title: Method and apparatus for supplying slurry fine powder

Coating process
Conventional plasma spraying using working gases such as Ar + hydrogen, Ar + nitrogen, and He + hydrogen has a flame center temperature of 5000 ° C to 30000 ° C. On the other hand, in conventional flame spraying using fuel and oxygen, oxygen / kerosene, air / kerosene, oxygen / hydrogen, oxygen / propylene, oxygen / propane, oxygen / ethylene, oxygen / acetylene, oxygen / natural gas mixed gas To generate heat. The flame spraying temperature is 2200 ° C to 3400 ° C, and is a continuous combustion reaction, so it is very difficult to control the temperature below this.

Powder supply device When a material with low thermal conductivity such as ceramics is instantaneously heated and melted, the finer the powder particle size, the better. Further, when the coating powder is fine, the surface roughness of the film is fine, and there is an advantage that the subsequent surface finishing step can be omitted. However, fine powder with a particle size of 0.1 μm to 5 μm tends to agglomerate, flows intermittently, and is difficult to stably feed.

Alpha Al ₂ O ₃ coating material oxide is transformed into γAl ₂ O ₃ at 1000 ° C. or more is dissolved at 2030 ° C.. Anatase TiO ₂ transforms to rutile TiO ₂ at 700 to 800 ° C. Spinel MgO.Al ₂ O ₃ dissolves at 2135 ° C. SiO ₂ dissolves at 1710 ° C. Hf ₂ O ₃ dissolves at 2812 ° C. Y ₂ O ₃ dissolves at 2460 ° C. CeO ₂ dissolves at 2600 ° C. ZnO dissolves at 1975 ° C. Gd ₂ O ₃ dissolves at 2310 ° C. Cr ₂ O ₃ dissolves at 2435 ° C. Sm ₂ O ₃ dissolves at 2350 ° C. Yb ₂ O ₃ dissolves at 2410 ° C.

The nitride AlN undergoes sublimation decomposition at 2450 ° C, and Si ₃ N ₄ sublimates at 1900 ° C. BN sublimes at 3000 ℃. NbN decomposes at 2050 ° C. CrN decomposes at 1500 ° C. VN dissolves at 2050 ° C. TiN dissolves at 2930 ° C. ZrN dissolves at 2980 ° C.

The carbide αSiC transforms at 2100 ℃ and decomposes at 2830 ℃. Cr ₃ C ₂ dissolves at 1800 ° C. WC dissolves at 2730 ° C. VC dissolves at 2830 ° C. TiC dissolves at 3180 ° C.

The boride MoB dissolves at 2180 ° C. CrB ₂ dissolves at 2760 ° C. TiB ₂ dissolves at 2980 ° C. ZrB ₂ dissolves at 3040 ° C. TaB ₂ dissolves at 3000 ° C.

In the case of conventional plasma spraying, it may be as high as 30000 ° C. When a fine powder of oxide Al ₂ O ₃ or SiO ₂ is introduced, it easily transforms or melts and decomposes, resulting in a base material. It is very difficult to coat. Further, nitrides AlN, Si ₃ N ₄ , BN, and carbide SiC having a low binding energy, which have a relatively low melting point and are susceptible to sublimation decomposition, are decomposed, and it is also very difficult to coat the substrate. ZrN, Hf ₂ O ₃ , TaC, and TiB ₂ have high melting points, and the temperature limit of gas spraying is about 3400 ° C, so the coating is severe.

Coating composition In addition to coating the base material in a mixed state of molten and semi-molten powder, the mixed state in which a part of the very thin surface of the unmelted + powder is melted, or all unmelted powder It is desired to form a sintered film by spraying onto a substrate by impact. In the film structure to provide functionality, a dense film is good for electrical insulation, a film with moderate pores is good for heat insulation, and there are isolated spherical pores for thermal shock resistance It is better, and high-temperature corrosion resistance and gas permeability require pores with vents.

  In conventional high-temperature flame spraying, the flame temperature is stably lowered to 2200 ° C or less, or the atmosphere temperature at the site where the ceramic fine powder is put into the frame is finely controlled, so that the fine, pore, lamellar, or It is difficult to coat spherical unmelted particles + melt mixed coating.

  The impact sintered coating method according to the present invention is burned in a combustion chamber using oxygen / kerosene, air / kerosene, oxygen / hydrogen, oxygen / propylene, oxygen / propane, oxygen / ethylene, oxygen / acetylene, oxygen / natural gas. , Generate a frame. In the combustion chamber, attach a gun tip tube to the gun tip, and incline the powder supply nozzle at two positions 180 ° toward the cylinder axis of the tip cylinder or four positions 90 ° with respect to the gun axis. Install. It burns in the combustion chamber, and a frame is formed on the gun with a narrowed cross section, and is accelerated. The air introduced from the rear compressed air injection nozzle and the powder whose temperature is adjusted by the combustion gas from the powder supply nozzle are injected onto the substrate on this accelerated frame. The powder that has reached the required temperature collides with the base material, generates heat due to impact energy, becomes a sintered state, and is coated on the base material. Of course, if the powder is maintained at a melting temperature or a semi-melting temperature or higher, coating in a molten state or a semi-molten state is possible.

  Since the fine powder forms a bridge in a narrow conveyance tube and cannot be stably supplied, the fine powder is conveyed in the form of a slurry. A ceramic fine powder with a particle size of 0.1 μm to 5 μm is stirred in ethyl alcohol, methyl alcohol or kerosene as a solvent to form a slurry. Even if powder having a particle size of 10 μm or more is present, it can be made into a slurry. It is sent to the tube by a pump, and acetylene gas, methane, ethane, butane, propane, or propylene is sent from the Y-shaped union of the tube and mixed. A mixture of the slurry powder and acetylene gas, methane, ethane, butane, propane, or propylene gas is conveyed to the powder supply nozzle.

  By using ethyl alcohol, methyl alcohol, or kerosene as the solvent for making the fine powder into a slurry, and using a gas composed of acetylene, methane, ethane, butane, propane, or propylene as the combustible gas, oxygen can be used. When the amount is large, it burns and generates heat, and when the amount is small, it cools without burning. By this balance, the temperature is adjusted by melting fine powder or heating. In order to disperse the fine powder slurry uniformly, the powder hopper is in contact with an ultrasonic vibrator by an ultrasonic generator.

As ceramic materials for coating, oxide ceramics, group IIa BeO, MgO, CaO, SrO, BaO, group IIb ZnO, CdO, group IIIa Al ₂ O ₃ , Ga ₂ O ₃ , In ₂ O ₃ , group IIIb Sc ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , Group IVa SiO ₂ , GeO ₂ , SnO ₂ , Group IVb TiO ₂ , ZrO ₂ , Hf ₂ O ₃ , ThO ₂ , Group Vb V ₂ O ₃ , Nb ₂ O ₃ , Ta ₂ O ₃ , VIb group Cr ₂ O ₃ , MoO ₃ , WO ₃ , UO ₃ , VIII iron group Fe ₂ O ₃ , Fe ₃ O ₄ , NiO and rare earth La ₂ O _{3, CeO 2, Ce 2 O} 3, Nd 2 O 3, Sm 2 O 3, Eu 2 O 3, Gd 2 O 3, Dy 2 O 3, Yb 2 O 3, etc. is preferable.

Group IIIa BN, AlN, GaN, InN, Group IIIb ScN, YN, LaN, Group IVa Si ₃ N ₄ , Ge ₃ N ₄ , Sn ₃ N ₄ , Group IVb TiN, ZrN, HfN Th ₃ N ₄ , Vb group VN, NbN, TaN, VIb group CrN, Mo ₂ N, WN, VIII iron group Fe ₄ N, rare earth LaN CeN, GdN, and the like are desirable.

As carbide ceramics, Group IIIa B ₄ C, Group IVa SiC, Group IVb TiC, ZrC, HfC, ThC, Group Vb VC, NbC, TaC, Group VIb Cr ₃ C ₂ , MoC, WC, UC, VIII iron group Fe ₃ C and rare earth YC are desirable.

As boride ceramics, TiB ₂ of Group _{IVb, ZrB 2, HfB 2, ThB} 6, MoB 2 of Group Vb TaB _2, VIb _{Group, WB 2, CrB 2, NbB} 2, UB 2, VIII iron group of NiB, FeB, CoB, etc. are desirable.

If the amount of oxygen in the fuel is greater than the theoretical oxygen amount, the combustion gas contains oxygen and reacts with acetylene, methane, ethane, butane, propane, propylene, or alcohol that is transported from the powder supply nozzle to generate heat. On the other hand, if the amount of oxygen relative to the fuel is less than the theoretical amount of oxygen, non-combustible fuel is contained and the temperature is lowered. Further, the flame is cooled without burning acetylene, methane, ethane, butane, propane, propylene or alcohols conveyed from the powder supply nozzle. Accordingly, when the oxygen amount is equal to or higher than the theoretical oxygen amount, the thermal spray material is heated at a high temperature. Conversely, when the oxygen amount is equal to or lower than the theoretical oxygen amount, the thermal spray material is heated at a low temperature. When alcohol is vaporized without burning, it takes heat of vaporization from the surroundings and exhibits a cooling effect.
Reference: C ₁₂ H ₂₆ + 37 / 2O ₂ → 12CO ₂ + 13H ₂ O

  The ratio of kerosene or combustion gas to oxygen, the total amount, the distance from the gun of the powder supply nozzle in the tip tube, the supply amount of acetylene, methane, ethane, butane, propane, or propylene, the slurry supply amount The atmospheric temperature of the frame of the heated particles or molten particles and the speed of the heated particles or molten particles are controlled by the balance between them, and the film structure that meets the target is built.

For example, when using a kerosene / oxygen mixture as fuel, the shock sintering coating conditions are as follows: oxygen gas pressure 0.5-1.5 MPa, flow rate 400-1900 liters / min, kerosene pressure 0.4-1.4 MPa, flow rate 0.2- 0.5 liter / min, compressed air pressure 0.2-1.5 MPa, 250-2000 liter / min, slurry powder supply rate 100-900 g / min, C ₂ H ₂ (acetylene) pressure 0.1-1.5 MPa, 20-600 Use liters / minute. The distance to the workpiece should be 70mm to 400mm from the tip tube tip.

The impact sintering coating conditions when using an acetylene / oxygen mixture as the fuel are as follows: oxygen gas pressure 0.15-0.3 MPa, flow rate 30-70 liters / minute, acetylene pressure 0.10-0.24 MPa, flow rate 15-55 liters / minute min, the compressed air pressure 0.2 to 1.5 MPa, in 100 to 1500 liters / min, the slurry powder supply amount from 100 to 900 g / min, C ₂ H ₂ (acetylene) pressure 0.3～1.5MPa, 60 to 600 liters / min To. The distance to the workpiece should be 50mm to 300mm from the tip tube tip.

  In the case of oxides, nitrides, carbides and borides that are easily sublimated and decomposed in the impact sintered coating, the flame temperature is lowered and the temperature is controlled with high precision, enabling the impact sintered coating. In addition, high-melting oxides, nitrides, carbides and borides can be similarly subjected to impact-sintering coating by raising the frame temperature.

  A simple powder supply system, solvent and gas used enable fine powder supply. An impact-sintered coating film using fine powder was made, and the surface finishing process could be omitted by reducing the surface roughness. Therefore, it was possible to suppress the increase in cost.

  Sintered film that lowers the frame temperature, controls the temperature accurately, and does not melt the impact-sintered coating film configuration, a dense lamellar film, a lamellar film containing unvented pores, or a lamellar film containing vented pores, It became possible to form spherical unmelted particles + melted composite film, and a film having a function that was impossible until now has been obtained.

Schematic diagram of impact sintered coating gun for implementing the impact sintered coating method of the present invention Schematic diagram of slurry powder and combustion gas supply device for carrying out the impact sintering coating method of the present invention

  As shown in the schematic diagram of FIG. 1, the impact sintering coating apparatus has a combustion chamber 1, introduces oxygen gas from an oxygen passage 2, and uses kerosene, acetylene, propylene, propane, ethylene, natural gas, etc. from a fuel passage 3. Introduce combustion gas and fuel liquid. Fuel and oxygen are mixed in the burner 4, introduced into the combustion chamber, and burned when ignited. The frame passes through a gun nozzle 5 with a reduced area. It reaches the tip tube 6 attached to the tip of the gun nozzle 5. The gun nozzle 5 has a compressed air passage 7 therein, and is configured so that the compressed air flows in a laminar flow on the inner surface of the tip tube 6 by the compressed air injection ring 8 and powder does not adhere to the inner surface of the tip tube 6. Yes. Further, the air exiting from the compressed air injection ring 8 is subjected to a combustion reaction with the combustion gas exiting from the powder supply nozzle 10.

  A mixture of the slurry powder and acetylene, methane, ethane, butane, propane, or propylene gas is introduced into the tip tube 6 from the slurry powder and the combustion gas passage 9, and the powder supply nozzle 10 faces the axis of the tip tube 6. It is installed with an inclination. Slurry powder and combustion gas are combusted in the combustion chamber 1 from the powder supply nozzle 10 and injected into the generated flame.

  A uniform slurry-like fine powder and combustion gas supply device will be described with reference to the schematic view of FIG. An ultrasonic vibrator 13 having an ultrasonic generator 12 is inserted into the slurry container 11 in the cylindrical shape. The frequency is changed according to the material, particle size and solvent of the fine powder and the optimum conditions are set, and the slurry fine powder is uniformly dispersed. The slurry fine powder is introduced into the slurry pump 14 and conveyed to the Y-shaped union 15. Adjust the flow rate with the number of rotations of the pump. The flow rate is confirmed with the slurry flow meter 16. On the other hand, the combustion gas stored in the combustion gas cylinder 17 is adjusted by a fuel gas adjustment valve and confirmed by a gas flow meter 18. These mixtures are introduced into the slurry powder and the combustion gas passage 9.

  When the theoretical oxygen amount is large relative to the fuel, the combustion gas contains oxygen, and acetylene, methane, ethane, butane introduced from the powder supply nozzle 10 on the inner surface of the tip tube 6 by the air from the compressed air injection nozzle, Combustion reaction with propane or propylene gas or alcohol in slurry form raises the flame temperature and heats the powder to a high temperature. When the theoretical oxygen amount is small relative to the fuel, acetylene, methane, ethane, butane, propane, or propylene gas is cooled without burning on the inner surface of the tip tube 9 portion, and the powder is heated at a low temperature. Since the inner diameters of the gun nozzle 5 and the tip tube 6 are narrow, the speed of the combustion gas is increased, and the heated particles or molten particles are accelerated and collide with the base material to form a film.

For an electrically insulating substrate that requires heat dissipation characteristics and thermal conductivity, it is necessary to create a dense film structure composed of a lamellar layer using Si ₃ N ₄ , AlN, and SiC fine powder. Si ₃ N ₄ has a decomposition temperature of 2000 ° C. or lower, and AlN has a sublimation decomposition temperature of 2450 ° C. or lower. The flame temperature must be maintained and accelerated to be coated. For materials that are easily decomposed, a sintered film is desirable.

For SiO ₂ films that require electrical insulation, it is necessary to create a dense film structure consisting of lamellar layers.

  For thermal shock resistance, it is better to have isolated spherical pores, and it is necessary to create a film with 10% to 25% pores. SiC and other materials must be accelerated and coated at temperatures below 2830 ° C.

  A lamellar layer containing vent holes is preferable for aeration and gas catalytic properties.

In order to improve the arc resistance at the time of sputtering, the surface of the film becomes smooth, and an uneven surface, that is, a surface roughness for holding the sputtered film is required. For that purpose, spherical unmelted particles + melt mixed film is preferable. The particles of αAl ₂ O _{3 having} a large particle size are not dissolved to the core, and a small amount of particles having a small particle size are dissolved. For this reason, the frame temperature is adjusted so that it does not overheat more than 2030 ° C.
The present invention will be described in detail with reference to examples.

  A SUS304 specimen having a size of 50 mm × 50 mm × plate thickness 2 mm was used. Before forming the film, it is washed in advance and a grit blast treatment is performed as a roughening treatment. Alumina grit 80 mesh is used and sprayed onto the test specimen substrate at a pressure of about 0.5 Mpa. The surface roughness after blasting was Ra10-15 μm.

  The powder and acetylene gas were stopped using the impact sintered coating gun shown in FIG. 1 and burned, and the test piece was heated from 50 ° C. to 150 ° C. for pre-heat treatment. This treatment removed moisture, water, and water vapor.

Mix with ethyl alcohol using CeO ₂ -15% CaO fine powder particle size 1μm-3μm. For a CeO ₂ -15% CaO bulk volume of 1, a volume of ethyl alcohol of 1.5 is placed in a slurry vessel 11 and is ultrasonicated to form a slurry. These mixtures are conveyed by a slurry pump 14 through a slurry conveying tube, mixed with acetylene through a Y-shaped union 15, and introduced into the slurry powder and the combustion gas passage 9. The distance from the tip tube tip 6 to the specimen base is kept at 150 mm, and the gun axis and specimen surface are held vertically. That is, the distance to the workpiece is 150 mm. The impact sintering coating conditions are summarized below.
[Conditions for impact-sintering coating]

Fuel kerosene: Pressure 0.8MPa, Flow rate 0.5L / min Oxygen gas: Pressure 1.0MPa, Flow rate 750L / min Compressed air: Pressure 0.5MPa, Flow rate 600L / min Powder supply rate CeO ₂ -15% CaO + ethyl alcohol: 450g / Minute Acetylene: Pressure 0.3MPa, Flow rate 70L / min

The thickness of the impact-sintered coating film on the test piece substrate thus obtained was 50 μm, and the surface roughness was Ra1 to 2 μm. As a result of observing this film cross section with an optical microscope, it is a structure having a sintered layer containing some pores. As a result of examining this film with an X-ray diffractometer, CeO ₂ and CaO were detected. The ionic conductivity of the CeO ₂ -15% CaO film was 70% of that of the CeO ₂ -15% CaO sintered body at 1000 ° C.

  A SUS304 specimen consisting of a 30 mm × 100 mm cylinder was used. Before forming the film, it is washed in advance and a grit blast treatment is performed as a roughening treatment. Alumina grit 60 mesh is used and sprayed onto the specimen substrate at a pressure of about 0.5 Mpa. The surface roughness after blasting was Ra10-15 μm.

  The powder and acetylene gas were stopped using the impact sintered coating gun shown in FIG. 1, and the test piece was heated from 50 ° C. to 150 ° C. for pre-heat treatment. This treatment removed moisture, water, and water vapor.

Si ₃ N ₄ powder is mixed with ethyl alcohol using 1 μm to 2 μm. A volume 2 of ethyl alcohol is put into a slurry container 11 with respect to 1 bulk capacity of Si ₃ N ₄ and is made into a slurry by applying ultrasonic waves. These mixtures are conveyed by a slurry pump 14 through a slurry conveying tube, mixed with acetylene through a Y-shaped union 15, and introduced into the slurry powder and the combustion gas passage 9. The distance from the tip of the tip tube 6 to the specimen base is maintained at 150 mm, and the gun axis and specimen surface are held vertically. The impact sintering coating conditions are summarized below.
[Shock-sintering coating conditions]

Fuel kerosene: Pressure 0.9MPa, Flow rate 0.45L / min Oxygen gas: Pressure 1.0MPa, Flow rate 600L / min Compressed air: Pressure 0.4MPa, Flow rate 500L / min Powder supply rate Si ₃ N ₄ + Ethyl alcohol: 500g / min Acetylene: pressure 0.4MPa, flow rate 60l / min

The thickness of the impact-sintered coating film on the test piece substrate thus obtained was 40 μm, and the surface roughness was Ra 3 to 4 μm. The cross-sectional structure of the film was observed with an optical microscope. The result was a structure composed of a sintered layer having a porosity of 15 to 25%. As a result of examining this film with an X-ray diffractometer, Si ₃ N ₄ was detected. Using the Si ₃ N ₄ film, a high-temperature thermal shock test was performed in which the film was rapidly cooled from 700 ° C. Good results were also obtained in repeated tests under severe thermal shock evaluation test conditions where large thermal stresses were generated at the interface. The thermal conductivity was 50% of that of the Si ₃ N ₄ sintered body.

  A SUS304 test piece of 20 mm × 150 mm × thickness 5 mm was used. Before forming the film, it is washed in advance and a grit blast treatment is performed as a roughening treatment. Alumina grit 60 mesh is used and sprayed onto the specimen substrate at a pressure of about 0.5 Mpa. The surface roughness after blasting was Ra10-15 μm.

  The powder and acetylene gas were stopped using the impact sintered coating apparatus shown in FIG. 1, and the test piece was heated from 50 ° C. to 150 ° C. for pre-heat treatment. This treatment removed moisture, water, and water vapor.

  Mix with methyl alcohol using TaC particle size 1μm to 3μm. For a TaC bulk capacity of 1, a volume of methyl alcohol of 1.5 is placed in a slurry vessel 11 and subjected to ultrasound to form a slurry. These mixtures are conveyed by a slurry pump 14 through a slurry conveying tube, mixed with acetylene through a Y-shaped union 15, and introduced into the slurry powder and the combustion gas passage 9. The distance from the tip of the tip tube 6 to the specimen base is maintained at 130 mm, and the gun axis and specimen surface are held vertically. The impact sintering coating conditions are summarized below.

[Conditions for impact-sintering coating]
Fuel kerosene: Pressure 0.7MPa, Flow rate 0.35L / min Oxygen gas: Pressure 0.8MPa, Flow rate 600L / min Compressed air: Pressure 0.4MPa, Flow rate 550L / min Powder supply rate TaC + Methyl alcohol: 300g / min Acetylene: Pressure 0.3 MPa, flow rate 80 l / min

  The thickness of the impact-sintered coating film on the test piece substrate thus obtained was 60 μm, and the surface roughness was Ra2 to 3 μm. The cross-sectional structure of this film was observed with an optical microscope, and the result was a structure having a lamellar layer containing a few pores. As a result of examining this film with an X-ray diffractometer, TaC was detected. The emitter characteristics of the TaC film were good, showing the same value as the sintered body.

  A specimen of SUS304 having a diameter of 50 mm and a thickness of 10 mm was used. Before forming the film, it is washed in advance and a grit blast treatment is performed as a roughening treatment. Alumina grit 60 mesh is used and sprayed onto the specimen substrate at a pressure of about 0.5 Mpa. The surface roughness after blasting was Ra10-15 μm.

  The powder and acetylene gas were stopped using the impact sintered coating gun shown in FIG. 1, and the test piece was heated from 50 ° C. to 150 ° C. for pre-heat treatment. This treatment removed moisture, water, and water vapor.

Mix with methyl alcohol using TiB ₂ particle size 1μm to 5μm. Against TiB ₂ bulk volume 1, to form a slurry with applying ultrasonic waves put capacity 1 methyl alcohol in a container. These mixtures are conveyed by a slurry pump 14 through a slurry conveying tube, mixed with acetylene through a Y-shaped union 15, and introduced into the slurry powder and the combustion gas passage 9. The distance from the tip tube tip 6 to the test piece base is kept at 120 mm, and the gun axis and the test piece surface are held vertically. That is, the distance to the workpiece is 120 mm. The impact sintering coating conditions are summarized below.

[Shock-sintering coating conditions]
Fuel acetylene gas: pressure 0.1 MPa, flow rate 25 liters / min oxygen gas: pressure 0.2 MPa, flow rate 40 l / min Compressed air: pressure 0.2 MPa, flow rate of 100 l / min powder feed amount TiB ₂ + methyl alcohol: 50 g / min of acetylene : Pressure 0.35MPa, Flow rate 70L / min

The thickness of the impact-sintered coating film on the test piece base material thus obtained was 110 μm, and the surface roughness was Ra 4 to 5 μm. The cross-sectional structure of this film was observed with an optical microscope, and the result was a structure having a lamellar layer containing a few pores. Further, TiB ₂ was detected as a result of examining this film with an X-ray diffractometer. A wet ball-on-disk test was conducted at 100 ° C. in a lubricating fluid of engine oil 5W-30 using SUJ2 bearing alloy φ6 mm balls on the TiB ₂ coating disk. The seizure load was three times higher than the seizure test between SUJ2 bearing alloys.

DESCRIPTION OF SYMBOLS 1 Combustion chamber 2 Oxygen passage 3 Fuel passage 4 Burner 5 Gun nozzle 6 Tip cylinder 7 Compressed air passage 8 Compressed air injection ring 9 Slurry powder + combustion gas passage 10 Powder supply nozzle 11 Slurry container 12 Ultrasonic generator 13 Ultrasonic vibrator 13 14 Slurry pump 15 Y-shaped union 16 Slurry flow meter 17 Combustion gas cylinder 18 Fuel gas adjustment valve 19 Gas flow meter

Claims (2)

A method of forming a ceramic coating, wherein a ceramic coating is formed on the surface of a substrate by thermal spraying,
A fuel constituting the mixed gas is kerosene, and a step of burning the mixed gas in a combustion chamber to generate a flame;
Preparing alcohols as a solvent, and dispersing ceramic powder having an average particle size of 0.1 to 5 μm in the solvent to obtain a slurry;
Preparing acetylene, methane, ethane, butane, propane or propylene as the combustion gas, and injecting the combustion gas and the slurry into the flame;
With
The ceramic powder is BeO, MgO, CaO, SrO, BaO, ZnO, CdO, Al ₂ O ₃ , Ga ₂ O ₃ , In ₂ O ₃ , Sc ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , SiO _{2. , GeO 2, SnO 2, TiO} 2, ZrO 2, Hf 2 O 3, ThO 2, V 2 O 3, Nb 2 O 3, Ta 2 O 3, Cr 2 O 3, MoO 3, WO 3, UO 3, Fe ₂ O ₃ , Fe ₃ O ₄ , NiO and rare earth La ₂ O ₃ , CeO ₂ , Ce ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Dy ₂ O ₃ , Yb ₂ O ₃ ,
The pressure of oxygen constituting the mixed gas is 0.5 to 1.5 MPa, the flow rate is 400 to 1900 liters / minute,
The kerosene constituting the mixed gas has a pressure of 0.4 to 1.4 MPa, a flow rate of 0.2 to 0.5 liter / min,
The distance from the tip of the tube tip to the base material is 70 to 400 mm,
The amount of oxygen with respect to the fuel is made larger than the theoretical amount of oxygen, the fuel in the mixed gas is burned, and the ceramic powder is heated by raising the flame to a high temperature by burning the solvent and the combustion gas. A method for forming a ceramic coating, wherein a ceramic coating is formed on the surface of the base material by spraying. A method of forming a ceramic coating, wherein a ceramic coating is formed on the surface of a substrate by thermal spraying,
The fuel constituting the mixed gas is hydrogen, propylene, propane, ethylene, acetylene or natural gas, and the flame is generated by burning the mixed gas in a combustion chamber;
Preparing alcohols as a solvent, and dispersing ceramic powder having an average particle size of 0.1 to 5 μm in the solvent to obtain a slurry;
Preparing acetylene, methane, ethane, butane, propane or propylene as the combustion gas, and injecting the combustion gas and the slurry into the flame;
With
The ceramic powder is BeO, MgO, CaO, SrO, BaO, ZnO, CdO, Al ₂ O _Three , Ga ₂ O _Three , In ₂ O _Three , Sc ₂ O _Three , Y ₂ O _Three , La ₂ O _Three , SiO ₂ , GeO ₂ , SnO ₂ TiO ₂ , ZrO ₂ , Hf ₂ O _Three , ThO ₂ , V ₂ O _Three , Nb ₂ O _Three , Ta ₂ O _Three , Cr ₂ O _Three , MoO _Three , WO _Three , UO _Three , Fe ₂ O _Three , Fe _Three O _Four , NiO and rare earth La ₂ O _Three , CeO ₂ , Ce ₂ O _Three , Nd ₂ O _Three , Sm ₂ O _Three , Eu ₂ O _Three , Gd ₂ O _Three , Dy ₂ O _Three , Yb ₂ O _Three Either
In order to completely burn the solvent and the combustion gas by balancing the ratio of the fuel and the oxygen amount, the total flow rate thereof, the flow rate of the solvent and the combustion gas with respect to them, and the distance from the tip of the cylinder tip to the base material The amount of oxygen is made larger than the theoretical amount of oxygen, the fuel in the mixed gas is combusted, and the ceramic powder is heated by heating the ceramic powder by burning the solvent and the combustion gas to inject the ceramic powder. And forming a ceramic coating on the surface of the substrate.

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