JP2013224475A - Particle for thermal spraying, method for forming thermally sprayed coating film, and thermally sprayed member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a particle for thermal spraying which provides a flat and smooth and compact thermally sprayed coating film having excellent flowability without the need of surface polishing processing.SOLUTION: A particle for thermal spraying is a particle used as a raw material for thermal spraying and is obtained by being subjected to surface treatment with at least one organosilicon compound selected from organoalkoxysilane, organohalogensilane, and organoalkoxy halogensilane, wherein an average particle diameter of the particle is 45 μm or less. The particle for thermal spraying has excellent flowability even when it is a small inorganic particle with a small particle diameter, and the surface of a coating film obtained by performing thermal spraying of the particle for thermal spraying becomes flat and smooth and compact and has excellent adhesion and corrosion resistance.

Description

  The present invention relates to a thermal spraying particle capable of improving the fluidity of a thermal spray material and forming a thermal spray coating having good quality characteristics, a thermal spray coating forming method using the particle, and a thermal spray member.

  Conventionally, a dense thermal spray coating is formed by spraying particles for thermal spraying on the surface of a base material made of metal or ceramics to improve the heat resistance, wear resistance, and corrosion resistance of the base material. As the spraying method, plasma spraying, high-speed flame (HVOF) spraying, and the like are widely used. In these thermal spraying methods, particles made of an inorganic material such as metal or metal oxide are used as the particles for thermal spraying.

  By the way, the thermal spraying particles are supplied to the thermal spraying gun through a thin conveying tube and ejected, but it is required that the thermal spraying particles can be stably and quantitatively supplied up to the plasma flame or flame flame at the time of thermal spraying. . This is because when the supply of thermal spraying particles becomes unstable, the thickness of the thermal spray coating formed becomes non-uniform.

On the other hand, as the particles for thermal spraying generally, the finer the particle diameter, the higher the adhesion with the substrate and the lower the porosity, the dense thermal sprayed coating can be obtained.
However, the supply of the particles for thermal spraying is greatly affected by the fluidity of the particles for thermal spraying, and if the particle size becomes too fine, there is a problem that the particles are likely to be clogged inside the hopper of the feeder, the nozzle or the transport pipe. In particular, when the thermal spraying particle is 30 μm or less, the problem of clogging is likely to occur, and when it is about 10 μm or less, the problem of clogging becomes prominent.
For this reason, when spray particles having a small particle diameter are used, it becomes difficult to stably supply the spray gun through a thin conveying tube, and the spray coating is not formed or even if formed, the spray coating has a porosity. High film adhesion deteriorates, resulting in problems such as insufficient corrosion resistance and wear resistance of the film.

So far, various studies have been conducted for the purpose of improving the fluidity of thermal spray particles. For example, Patent Document 1 discloses particles for thermal spraying having an average particle diameter of 10 μm or more and 80 μm or less made of spherical particles of rare earth elements. Further, Patent Document 2 discloses a thermal spraying particle that is formed in a spherical shape as a whole and has a recess formed in a part of its outer peripheral surface, and has a particle diameter (D ₅₀ ) of 10 μm or more and 50 μm or less. .
These have been improved in fluidity by optimizing the particle shape, but there is a problem that it is expensive to produce spherical particles having a spherical particle shape or a recess. Moreover, in the said method, the fine powder less than 10 micrometers which tends to cause a fluid fall is removed, and possibility that it cannot apply to the particle for thermal spraying less than 10 micrometers is high.

On the other hand, Patent Document 3 contains 50% by volume or more of a hard carbide particle phase such as tungsten carbide having an average particle size of 5 μm or less, and 10% by volume or more of a metal phase such as Co, and each product particle contains Thermal spray particles having a cross-sectional porosity of 30% or less are disclosed.
Although carbide hard particles with an average particle size of 5 μm or less are used, the carbide hard particles have high physical properties and are not fluidly applicable to conventional inorganic materials such as metals and metal oxides. The coating is a so-called cermet in which hard carbide particles are bound with a metal phase, and is different from a dense sprayed coating in which an inorganic material such as metal or metal oxide is melted.

JP 2002-332559 A JP 2011-137194 A Japanese Patent Laid-Open No. 5-86452

As described above, conventional thermal spray particles are not sufficient in terms of improving fluidity with respect to small-diameter particles, and there is room for improvement.
Under such circumstances, an object of the present invention is to provide particles for thermal spraying that are excellent in fluidity even in the case of inorganic particles having a small particle diameter and that provide a smooth and dense thermal spray coating without being subjected to surface polishing. . Another object of the present invention is to provide a thermal spray coating forming method and thermal spray member using the thermal spray particles.

  As a result of intensive studies to solve the above problems, the present inventor has found that by coating the particles for thermal spraying surface-treated with a specific organosilicon compound, the fluidity is excellent even in the case of a small particle size. The present invention has been reached.

That is, the present invention relates to the following inventions.
<1> Particles used for thermal spraying raw material,
Particles for thermal spraying that are surface-treated with at least one organic silicon compound selected from organic alkoxysilanes, organic halogen silanes, and organic alkoxyhalogen silanes, and whose average particle diameter is 45 μm or less.
<2> The particles for thermal spraying according to <1>, wherein an angle of repose is 55 ° or less.
<3> A method for forming a thermal spray coating, in which the thermal spraying particles according to <1> or <2> are sprayed on a substrate surface.
<4> A thermal spray member provided with a thermal spray coating formed by thermal spraying the thermal spray particles according to <1> or <2> on a substrate surface.

The particles for thermal spraying of the present invention are excellent in fluidity because the inorganic particles are surface-treated with an organosilicon compound. Therefore, fluidity can be improved even when the particle size is small. Therefore, it is possible to supply powder with a small particle size that could not be supplied with a powder supply machine until now, and spraying the inorganic particles onto the base material enables smooth and dense sprayed coating with high hardness. Can be obtained. Further, since the surface of the thermal spray particles of the present invention is surface-treated with an organosilicon compound, it is hardly affected by humidity, has little deterioration, and is excellent in long-term storage stability.
The thermal spray member obtained by thermal spraying the thermal spray particles has a smooth and dense coating surface and is excellent in adhesion, wear resistance and corrosion resistance.

It is a figure which shows the relationship between the average particle diameter of an alumina particle, and a repose angle. It is a figure which shows the relationship between the average particle diameter of an alumina particle, and a flow time. It is a figure which shows the relationship between the supply scale and supply amount of the surface untreated alumina particles. It is a figure which shows the relationship between the supply scale and supply amount of the alumina particle surface-treated with dimethyldiethoxysilane. It is a X-ray-diffraction pattern of the thermal spray coating in the thermal spray member of Example 1 and Example 3, and alpha alumina particle

  Hereinafter, the present invention will be described in detail with reference to examples and the like, but the present invention is not limited to the following examples and the like, and can be arbitrarily modified and implemented without departing from the gist of the present invention.

  The present invention is a particle used as a thermal spray raw material, which is surface-treated with at least one organic silicon compound selected from organic alkoxysilane, organic halogen silane, and organic alkoxyhalogen silane, The present invention relates to particles for thermal spraying having an average particle diameter of 45 μm or less.

  In the particles for thermal spraying of the present invention, inorganic particles composed of metals, metal oxides, other ceramics and the like (hereinafter, these may be collectively referred to simply as “inorganic particles”) are surface-treated with an organosilicon compound, The surface is coated with an organosilicon compound, and fluidity is improved as compared to uncoated particles due to the lubricity of the organosilicon compound present on the surface.

As such inorganic particles, conventionally known spraying raw materials such as metals, metal oxides, ceramics and the like can be used.
Examples of the metal include one selected from Cu, Ni, Cr, Co, Fe, Al, Mo, W, C, B, Si, Y, Mg, Mn, P, Zn, V, Ta, In, and the like. The above mixtures or alloy bodies, self-fluxing alloy materials and the like can be mentioned.

Examples of the metal oxide include alumina, titania, chromia, gray alumina, aluminum titanate, yttria, alumina / zirconia, zircon sand, calcia stabilized zirconia, magnesia stabilized zirconia, yttria stabilized zirconia, nickel oxide, and the like. Can be mentioned.
Examples of other ceramics include Cr ₃ C ₂ , WC, TiC, SiC, ZrC, MoB ₂ , B ₄ C, TiB ₂ , ZrB ₂ , TiN, ZrN, Si ₃ N ₄ , and AlN. These can be used alone or in the form of granulated powder or sintered powder with metal.
Among these, alumina, particularly α-alumina is preferably used.

The inorganic particles may be used alone or in combination of two or more (including a combination of metals, metal oxides and other ceramics).
The shape of the inorganic particles is not particularly limited, and for example, a spherical shape, a square shape, or a scale shape can be used.

In the particles for thermal spraying of the present invention, the inorganic particles have an average particle size of 45 μm or less, preferably 25 μm or less, more preferably 10 μm or less, and particularly preferably 5 μm or less. In the present specification, “average particle diameter” means the value of D ₅₀ measured with a laser diffraction particle size distribution meter.
For the particle size distribution, a laser diffraction particle size distribution analyzer (LS230, manufactured by BECKMAN-COULTER) was used. The laser diffraction particle size distribution meter measures the particle size distribution by obtaining a diffraction pattern of laser light having a wavelength of 750 nm depending on each particle diameter of the particle group. Particles having a diameter of 0.4 μm to 900 μm can be measured.
Note that when the average particle diameter of the thermal spray material is larger than 45 μm, the fluidity is good and the powder supply tends to be sufficiently stable even with a normal powder feeder.
Those having these particle sizes are usually inferior in fluidity, but a significant improvement in fluidity is observed by using the particles for thermal spraying of the present invention surface-treated with the organosilicon compound according to the present invention.

  In addition, the lower limit of the size of the inorganic particles is determined within a range in which the fluidity of the thermal spraying particles of the present invention for surface treatment is maintained, and depends on the type of the organosilicon compound used, but usually the average particle size The diameter is 0.5 μm or more, preferably 0.8 μm or more, and more preferably the average particle diameter is 1 μm or more.

The thermal spray particles of the present invention preferably have an angle of repose of 55 ° or less, more preferably 50 ° or less, and still more preferably 45 ° or less. Here, the angle of repose means a low angle obtained by dropping from a funnel having a certain height onto a horizontal substrate and calculating from the diameter and height of the generated conical deposit. JIS R 9301 It can be measured according to the angle of repose of 2-2 alumina powder.
If the angle of repose exceeds 60 °, the fluidity is lowered and the powder cannot form and supply a bridge in the hopper of the powder feeder.

Examples of the organosilicon compound used for the surface treatment include organoalkoxysilanes, organohalogen silanes, and organoalkoxyhalogen silanes.
Specific examples include methyltrichlorosilane, methyldichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, trifluoropropyltrichlorosilane, tetramethoxysilane, methyltrimethoxysilane, and dimethyldimethoxysilane. , Phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, decyltrimethoxysilane, hexa Examples include methyldisilazane, trifluoropropyltrimethoxysilane, and ethyltriethoxysilane. These organosilicon compounds can be used alone or in combination.
In the particles for thermal spraying of the present invention, the fluidity is improved by the surface treatment with these organosilicon compounds, but considering the degree of improvement in fluidity, methyldichlorosilane, dimethyldichlorosilane, phenyltrichlorosilane, dimethyldimethoxysilane, Phenyltrimethoxysilane, dimethyldiethoxysilane, and diphenyldiethoxysilane are preferred.

  In the particles for thermal spraying according to the present invention, the amount of the organic silicon compound for surface-treating the inorganic particles is usually 0.01 to 5.0 wt% based on the weight of the inorganic particles, although it depends on the type of the organic silicon compound. Preferably, it is 0.01 to 1.0 wt%. If it is less than 0.01 wt%, improvement in lubricity is not recognized, and there is a possibility that fluidity may not be improved, and even if it exceeds 5.0 wt%, it is difficult to recognize any further effect.

The surface treatment of the inorganic particles with an organosilicon compound can be performed by bringing the inorganic particles and the organosilicon compound into contact with each other.
The contact method is not particularly limited. For example, a method in which the inorganic particles are immersed in a solution in which an organic silicon compound is dissolved in an appropriate solvent and then the solvent is removed and dried, or the organic silicon compound is directly or organic silicon. The method of spraying the solution containing a compound on the said inorganic particle and making it adhere to the surface is mentioned.

The coating substance which coat | covers the surface of the inorganic particle formed by surface treatment is a polymerization reaction product obtained by reaction of an organosilicon compound and the water | moisture content of a particle | grain surface. For the polymerization of the organosilicon compound, water adsorbed on the inorganic particles is usually used.
In order to produce the particles for thermal spraying according to the present invention, the surface of the inorganic particles is reacted with an organosilicon compound and moisture, and the particle surface is coated with the polymerization product.
In such coating treatment, the organosilicon compound may be used as it is, or the compound may be dispersed or dissolved in an organic solvent or a pH-adjusted aqueous solution. Inorganic particles are dispersed in such an organosilicon compound or a solution or dispersion thereof, and the suspension is allowed to stand or stir to coat or react bond the organosilicon compound on the surface of the inorganic particles.
The organic solvent used here is not particularly limited as long as it can dissolve the organosilicon compound. For example, alcohol solvents such as methanol and ethanol, aliphatic hydrocarbon solvents such as hexane, toluene and the like. Aromatic hydrocarbon solvents can be used. The aqueous solution adjusted to pH may be an aqueous solution adjusted to pH = 3 to 5 by adding acetic acid to water. The method for distilling off the organic solvent is not particularly limited, and various known solvent distilling methods can be used. For example, a method using an evaporator, a method of volatilizing at about room temperature to 100 ° C., normal pressure or reduced pressure A distillation method, a spray drying method, a fluidized bed drying method, or the like can be used.
The treatment temperature is preferably raised to a temperature not lower than room temperature and not higher than a temperature at which the inorganic particles do not react with each other.
In addition, as a dry production method, inorganic particles having an average particle size of 45 μm or less using a commonly used mixer such as a ball mill, a vibration mill, a planetary pulverizer, a jet mill, a mechanical stirring blade mixer, a container rotating mixer, etc. The above-mentioned organosilicon compound may be used.

  As a specific example of a suitable production method, dimethyldiethoxysilane is used as the organosilicon compound in a range of 0.01 to 5 wt% (for example, 0.05 to 5 g) with respect to the weight of the inorganic particles. Inorganic particles (for example, 100 g) are added to a solution mixed and dissolved in an organic solvent such as ethanol. The obtained mixed solution is heated and stirred from room temperature to about 100 ° C. for 0.1 to 2 hours, dried at 20 to 150 ° C. to distill off the organic solvent, and has an organic silicon compound film on the surface of the inorganic particles. Thermal spray particles can be obtained.

The thermal spray particles of the present invention have improved fluidity by surface treatment as described above, and can be suitably applied to conventionally known plasma spraying, high-speed flame (HVOF) spraying, reduced pressure plasma spraying, cold spray spraying, and the like.
It can be obtained by forming a film on the surface of the substrate by plasma spraying the above-mentioned particles for spraying, high-speed flame spraying, cold spray spraying, low pressure plasma spraying, or the like. Here, the plasma gas is not particularly limited, and nitrogen / hydrogen, argon / hydrogen, argon / helium, argon / nitrogen, argon alone, nitrogen alone, or the like can be used.
High-speed flame spraying is performed using kerosene, light oil, kerosene, propylene, oxygen, or the like.
Cold spray spraying is performed using helium, halogen, nitrogen, air, or the like.
The thermal spraying conditions and the like are not particularly limited, and may be set as appropriate according to specific materials such as a base material and thermal spraying particles, the use of the resulting thermal spray member, and the like.

The fluidity of the particles for thermal spraying of the present invention is preferably 50 seconds / 50 g or less, more preferably about 30 seconds / 50 g or less. However, in the powder feeder, there is no pulsation in the end. The condition is that a fixed amount can be supplied.
Here, “fluidity” means a value measured according to JIS Z2504 (apparent density test method for metal powder).

Next, the thermal spraying method and thermal spray member of the present invention will be described.
The thermal spraying method of the present invention is characterized in that the above-mentioned thermal spraying particles of the present invention are sprayed on the surface of a substrate. Moreover, the thermal spray member of the present invention is obtained by the thermal spraying method of the present invention, and is characterized by including a thermal spray coating formed by spraying the above-described thermal spraying particles of the present invention on the surface of a base material.
Since the particles for thermal spraying of the present invention have high fluidity, it is difficult for the thermal spraying gun to be clogged with the inside of a hopper of a powder feeder or a thin conveying tube. Therefore, even if spray particles having a small particle size of 10 μm or less are used, stable supply can be achieved without pulsation. Therefore, in the thermal spraying method of the present invention using the particles for thermal spraying, the sprayed coating formed is smooth and dense, has a low porosity, and has good adhesion to the substrate.

In the thermal spraying method of the present invention, the thermal spraying method is not particularly limited, and can be suitably applied to conventionally known plasma spraying, high-speed flame (HVOF) spraying, reduced pressure plasma spraying, cold spray spraying, and the like.
Among the thermal spraying methods, high-speed flame (HVOF) spraying enables spraying of inorganic particles such as alumina, chromium oxide, and yttria, which could only be formed by plasma spraying, by using small spray particles. Therefore, it becomes possible to produce a sprayed coating with little composition change, which is a particularly suitable spraying method.
The spraying conditions and the like are not particularly limited, and the type of base material, the type and particle size of inorganic particles in the particles for spraying, the type of organosilicon compound used for the surface treatment, the use of the resulting sprayed member, etc. It may be set as appropriate in consideration.

  In the thermal spray member of the present invention, the base material is not particularly limited, and a thermal spray base material such as a general metal, alloy, ceramics, or glass can be used. For example, specific examples include metals such as aluminum, iron, nickel, chromium, tin, silicon, copper, and zinc, alloys thereof, oxides, nitrides, and carbides.

  In the thermal spray member of the present invention, the thickness of the thermal spray coating formed on the surface of the base material varies depending on the thermal spraying process, and thus is not particularly limited, but is usually 100 to 3000 μm, preferably 200 to 500 μm. If the thickness of the sprayed coating is too thin, the corrosion resistance and wear resistance of the sprayed coating may be insufficient, and the effect of forming the sprayed coating may not be obtained. On the other hand, if the thermal spray coating is too thick, cracks may easily occur in the thermal spray coating, and peeling may occur easily.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is changed.

The raw materials used and the evaluation method are as follows.
(Alumina particles)
(1) Alumina particles A (AX3-32, Micron)
Average particle size: 3 μm
Shape: Spherical (2) Alumina particles B (# 3000, Showa Denko)
Average particle size: 3 μm
Shape: Rectangular (3) Alumina particles C (AX10-32, Micron)
Average particle size: 10 μm
Shape: Spherical (4) Alumina particles D (17T, Showa Denko)
Average particle size: 12 μm
Shape: Rectangular (5) Alumina particles E (16T, Showa Denko)
Average particle size: 21 μm
Shape: Rectangular

(Organic silicon compound)
(1) phenyltrichlorosilane (2) 3-methacryloxypropyltrimethoxysilane (3) dimethyldiethoxysilane (4) methyldichlorosilane (5) vinyltrimethoxysilane (6) diphenyldiethoxysilane (7) dimethyldimethoxysilane (8) Dimethyldichlorosilane (9) Phenyltrimethoxysilane (10) 3-Glycidoxypropyltrimethoxysilane (11) 3-Aminopropyltrimethoxysilane (12) Hydrolyzable group-containing siloxane (13) 3-Amino Propylmethyldimethoxysilane (14) 3-acryloxypropyltrimethoxysilane

Powder feeder: TPF-1012 made by TPA

The evaluation method of the particles for thermal spraying and the thermal spray coating is as follows.
(1) Fluidity The fluidity was evaluated by a method based on JIS-Z2504. Specifically, the bottom of the funnel is plugged, 50 g of the thermal spray particles are put into the funnel, and the bottom plug is removed, and at the same time, a vibration with a vibration frequency of 60 Hz and an amplitude of 0.4 mm is applied, and the total amount of particles flows down. The number of seconds required for the measurement was measured at n = 5, and the measurement results were arithmetically averaged.
(2) Angle of repose By the method according to the angle of repose of alumina powder of JIS R 9301-2-2, it was dropped on a horizontal substrate from a funnel of a certain height, and the diameter and height of the generated conical deposits The low angle was calculated from this, the low angle was measured at n = 5, and the measurement results were arithmetically averaged.
(3) Film hardness Film hardness was measured using a micro Vickers hardness meter (MVK-A, manufactured by Akashi Seisakusho). The test load was 2.94 N, the holding time was 15 seconds, the hardness of the film cross section was measured at n = 5, and the measurement results were arithmetically averaged.
(4) Film surface roughness The film surface roughness was measured using a surface roughness meter (SJ-201P, Mitutoyo) using a contact-type surface roughness meter. The roughness of the film surface was measured at n = 5, and the measurement results were arithmetically averaged.
(5) Crystallinity evaluation (X-ray diffraction)
Using an X-ray diffractometer (X'Pert PRO MPD, Panalical), X-ray diffraction is performed on alumina powder and alumina coating (coating prepared by HVOF spraying and coating prepared by plasma spraying) to identify the crystal structure Went.

Evaluation 1: Relationship between kind of organosilicon compound and fluidity evaluation Particle 1 for thermal spraying
Alumina particles A were used as the inorganic particles, and phenyltrichlorosilane was used as the organosilicon compound.
100 g of alumina powder (average particle size 3 μm) was added to a solution obtained by mixing 1.0 g of phenyltrichlorosilane in 100 ml of ethanol, heated and stirred at 80 ° C. for 1 hour, dried at 100 ° C., and phenyl on the surface. Thermal spray particles 1 having a trichlorosilane coating were obtained.
Table 1 summarizes the results of the organosilicon compounds used, the visual powder state, the fluidity evaluation, and the angle of repose.

Thermal spray particles 2-15
Thermal spray particles 2 to 15 were obtained in the same manner as the thermal spray particle 1 manufacturing method except that the organosilicon compound shown in Table 1 was used as the organosilicon compound.
Table 1 summarizes the results of the organosilicon compounds used, the visual powder state, the fluidity evaluation, and the angle of repose.

Thermal spray particles 16, 17
Alumina particles A and B were not subjected to surface treatment as inorganic particles, and were used as spray particles 16 and 17 as they were. Table 1 summarizes the results of visual powder state, fluidity evaluation, and angle of repose.

Evaluation 2: Relationship between average particle diameter of alumina particles, angle of repose, and flow time Alumina particles using dimethyldiethoxysilane as the organosilicon compound and alumina particles A to E having different particle diameters as the inorganic particles The relationship between the average particle diameter, the angle of repose and the flow time was evaluated.
FIG. 1 shows the relationship between the average particle diameter of alumina particles and the angle of repose. FIG. 2 shows the relationship between the average particle diameter of alumina particles and the flow time (seconds / 50 g).
As shown in FIG. 1, it can be seen that alumina particles having a surface treatment with dimethyldiethoxysilane have smaller repose angles than untreated alumina particles in alumina particles of all particle sizes.
It was also found that the alumina particles surface-treated with dimethyldiethoxysilane were clearly larger in terms of fluidity than untreated alumina particles. In particular, it was found that when the average particle size is small and the particle size is 10 μm or less, the flow time becomes fast, and the difference from untreated alumina particles becomes remarkable.

Evaluation 3: Result of Supply Flow Curve of Flowability Improvement Powder FIG. 3 shows a supply curve of a powder supply machine for untreated powder. Moreover, the supply curve of the powder supply machine of a process powder is shown in FIG.
As for the untreated powder, alumina powder having an average particle diameter of 3 μm and 10 μm could not be quantitatively supplied by a powder feeder, but 12 μm and 21 μm alumina powder could be quantitatively supplied. The treated powder with improved fluidity can quantitatively supply alumina powder having an average particle size of 3 μm and 10 μm. The supply amount of 12 μm and 21 μm alumina powder was also improved. Therefore, the quantitative supply performance was improved by processing the powder.

Evaluation 4: Evaluation of thermal spray coating on thermal spray member Using SS400 as a base material, thermal spray was performed under the following conditions to obtain thermal spray members of Examples 1 to 3 shown in Table 2.

Example 1 (plasma spraying)
Thermal spray particles: 3 μm alumina particles B + dimethyldiethoxysilane Equipment: TPS-100
Thermal spraying conditions:
Output: 200V x 500A
Plasma gas: Ar / H ₂ = 70/70 slm
Powder supply rate: 4.2 kg / h
Example 2 (plasma spraying)
Thermal spray particles: 21 μm alumina particles E + dimethyldiethoxysilane Equipment: TPS-100
Thermal spraying conditions:
Output: 200V x 500A
Plasma gas: Ar / H ₂ = 70/70 slm
Powder supply: 4.5 kg / h
Example 3 (HVOF spraying)
Thermal spray particles: 3 μm alumina particles B + dimethyldiethoxysilane Equipment: JP5000
Thermal spraying conditions:
Output: 86psi (kerosene / oxygen)
Powder supply: 3.8 kg / h

(1) Evaluation of film hardness and film surface roughness Table 2 shows the results of evaluating the hardness and surface roughness of the sprayed film in the thermal spray members of Examples 1 to 3.
The plasma film with an average particle diameter of 3 μm had an average hardness Hv = 1027, and the plasma film with a diameter of 21 μm had an average hardness Hv1012. It was found that a finer film with a higher particle size formed a higher hardness.
The average roughness was Ra = 4.38 μm for the 21 μm plasma coating, Ra = 3.91 μm for the 3 μm plasma coating, and Ra = 1.68 μm for the 3 μm HVOF coating. From this result, it was found that the HVOF coating is much smaller in roughness than the plasma coating and can form a smooth coating. It was also found that a film with a smaller average particle diameter can be formed with a smaller roughness in the plasma film.

(2) Crystallinity Evaluation of Thermal Sprayed Coating For Example 1 (plasma sprayed coating, alumina particle B 3 μm) and Example 3 (HVOF sprayed coating, alumina particle B 3 μm), the crystallinity of the sprayed coating was evaluated.
FIG. 5 shows X-ray diffraction patterns of the thermal spray coatings of Example 1 and Example 3. For comparison, FIG. 5 also shows an X-ray diffraction pattern of 3 μm of alumina particles B (α-Al ₂ O ₃ ) without spraying.
HVOF sprayed coatings made with α-Al ₂ O ₃ particles have higher crystallinity and α-rich crystal phase than plasma sprayed coatings, and transformation to γ-Al ₂ O ₃ is very unlikely It was found that a film could be formed. It was found that a film with little composition change can be produced by forming a film of fine powder with HVOF. The well-melted plasma sprayed coating was a γ-rich coating.

Currently, thermal spraying technology is applied in the semiconductor industry as an anti-plasma erosion countermeasure for internal jig materials in plasma etching equipment, is applied to piston-related parts and oxygen sensors in the automotive industry, is applied to anilox rolls in the printing industry, and is also used in the power generation industry. Is applied to improve corrosion resistance and wear resistance as a measure to extend the life of steam generating boiler tubes. In these applications, the expectation of process and material development is high, and it is desired to improve the film performance by densifying the film, improving the adhesion, and reducing the film thickness.
Under such circumstances, the thermal spray particles of the present invention are excellent in fluidity and can be stably supplied. Therefore, a smooth and dense thermal spray coating can be provided, which is industrially promising.

Claims (4)

Particles used for thermal spraying raw material,
It is surface-treated with at least one organic silicon compound selected from organic alkoxysilanes, organic halogen silanes, and organic alkoxy halogen silanes, and the average particle diameter of the particles is 45 μm or less. Thermal spray particles.   The thermal spraying particle according to claim 1, wherein an angle of repose is 55 ° or less.   A method for forming a thermal spray coating, comprising spraying the particles for thermal spraying according to claim 1 or 2 onto a substrate surface.   A thermal spray member comprising a thermal spray coating formed by thermal spraying the thermal spray particles according to claim 1 on a substrate surface.