JP6955601B2 - Method for forming thermal spray slurry, thermal spray coating and thermal spray coating - Google Patents

Description

The present invention relates to a thermal spraying slurry containing thermal spray particles, a thermal spray coating, and a method for forming the thermal spray coating.

The thermal spray coating is formed by spraying the thermal spray particles onto the substrate. The sprayed coating is used in various applications depending on the characteristics of the material constituting the sprayed particles. For example, the aluminum oxide sprayed coating is used as a protective coating for various members because aluminum oxide exhibits high electrical insulation, wear resistance and corrosion resistance (see, for example, Patent Document 1). Further, the yttrium oxide sprayed coating is used as a protective film for members in semiconductor device manufacturing equipment because yttrium oxide exhibits high plasma erosion resistance (etching resistance and corrosion resistance). Such a thermal spray coating can be formed not only by spraying the thermal spray particles in the form of powder but also in the form of a slurry containing the thermal spray particles (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2014-240511 Japanese Unexamined Patent Publication No. 2010-150617

However, there is a problem that thermal spraying of slurry has lower thermal spraying efficiency than thermal spraying of powder. In order to improve the thermal spraying efficiency of slurry spraying, it is effective to increase the amount of thermal spray particles contained in the slurry. However, in this case, the fluidity of the slurry is lowered, and as a result, it becomes difficult to form a sprayed coating. Further, as the degree of integration of semiconductor devices is improved, more precise control is required for contamination by particles (foreign substances). For example, suppression of finer particles, which has not been a problem in the past, is required, and further plasma erosion resistance is required for the thermal spray coating.

Therefore, an object of the present invention is to provide a thermal spraying slurry capable of satisfactorily forming a thermal spraying film having better plasma erosion resistance. Another object of the present invention is to provide a thermal spray coating having excellent plasma erosion resistance and a method for forming the thermal spray coating, using the spraying slurry.

In order to solve the above problems, the invention disclosed herein provides a thermal spraying slurry containing a thermal spray particle composed of a compound containing yttrium (Y) and a halogen element (X) as constituent elements, and a dispersion medium. .. The thermal spraying slurry has a content of the thermal spray particles of 10% by mass or more and 70% by mass or less, and the viscosity of the thermal spraying slurry is 300 mPa · s or less.
The compound containing yttrium (Y) and the halogen element (X) is a material having significantly higher plasma erosion resistance than yttrium oxide. According to such a configuration, the fluidity of the spraying slurry containing the sprayed particles composed of the yttrium and the compound containing a halogen element and the film forming property can be suitably compatible with each other. Further, it is preferable because the thermal spray coating formed by using this thermal spraying slurry can enhance the erosion resistance to halogen-based plasma.

In the technique disclosed herein, the halogen-based plasma is typically a plasma generated by using a plasma-generating gas containing a halogen-based gas (halogen compound gas). For example, specifically, fluorine-based gases such as _{SF 6} , CF ₄ , CHF ₃ , ClF ₃ , and HF, which are used in a dry etching process in the production of a semiconductor substrate, _{and chlorine such as Cl 2} , BCl ₃ , and HCl. A typical example is a plasma generated by using one kind such as a system gas, a bromine gas such as HBr, and an iodine gas such as HI alone or in combination of two or more. These gases may be a mixed gas with an inert gas such as argon (Ar).

In a preferred embodiment of the thermal spraying slurry disclosed herein, the halogen element (X) is fluorine and the thermal sprayed particles include yttrium fluoride. With such a configuration, it is possible to suitably form a thermal spray coating having excellent plasma erosion resistance not only for chlorine-based plasma but also for fluorine-based plasma generated by, for example, a plasma generating gas containing a fluorine-containing gas.

In a preferred embodiment of the thermal spraying slurry disclosed herein, the thermal sprayed particles further contain a compound containing oxygen (O) as a constituent element. With such a configuration, the plasma erosion resistance of the thermal spray coating formed by using this thermal spraying slurry to halogen-based plasma can be further enhanced.

In a preferred embodiment of the thermal spraying slurry disclosed herein, the halogen element (X) is fluorine and the thermal sprayed particles include yttrium oxyfluoride. It is preferable that the thermal spraying slurry contains the thermal spray particles made of yttrium oxyfluoride because the plasma erosion resistance to the fluorine-based plasma generated by the plasma generating gas containing the fluorine-containing gas is enhanced.

In a preferred embodiment of the thermal spraying slurry disclosed herein, the thermal spray particles consist of the group consisting of _{Y 5} O ₄ F ₇ , Y ₆ O ₅ F ₈ , Y ₇ O ₆ F ₉ and Y ₁₇ O ₁₄ F _23. At least one selected is contained in a proportion of 95% by mass or more. With such a configuration, the thermal spray coating formed of the thermal spraying slurry, it is possible to reduce the proportion of yttrium oxide which can be a cause of particles (Y 2 _{O 3).}

In a preferred embodiment of the thermal spraying slurry disclosed herein, the thermal spraying particle contained in the thermal spraying slurry has a sedimentation rate of 30 μm / sec or more. With such a configuration, the fluidity of the sprayed particles can be maintained high, and a dense sprayed coating having a small porosity (for example, 10% or less) can be suitably formed.

In a preferred embodiment of the thermal spraying slurry disclosed herein, a dispersant is further contained. Even with such a configuration, it is possible to maintain high fluidity of the thermal spraying particles while increasing the thermal spraying efficiency of the thermal spraying slurry.

In a preferred embodiment of the thermal spraying slurry disclosed herein, a viscosity modifier can be further contained. As a result, even in the case of a spraying slurry having a high solid content concentration, it is possible to suppress an excessive increase in viscosity and maintain good fluidity.

In a preferred embodiment of the thermal spraying slurry disclosed herein, it further contains a flocculant. With such a configuration, even if the sprayed particles in the sprayed slurry are precipitated, the condensation of the sprayed particles can be prevented and the redispersibility of the sprayed particles can be enhanced.

In a preferred embodiment of the thermal spraying slurry disclosed herein, the average particle size of the thermal sprayed particles is 1 nm or more and less than 200 nm. With such a structure, it is possible to make it difficult for the sprayed particles to settle in the sprayed slurry.

In a preferred embodiment of the thermal spraying slurry disclosed herein, the average particle size of the thermal sprayed particles is 200 nm or more and 6 μm or less. With such a configuration, it is possible to suppress the deterioration of the thermal spraying particles when the thermal spraying slurry is sprayed.

According to the above-mentioned thermal spraying slurry disclosed here, the amount (solid content concentration) of the thermal sprayed particles contained in the slurry is increased even when the thermal sprayed particles composed of a compound containing yttrium and a halogen element are used. At the same time, since the fluidity of the slurry can be maintained, thermal spraying can be carried out with high thermal spraying efficiency. Therefore, the sprayed product of this thermal spraying slurry becomes a thermal spray coating containing yttrium and halogen elements as constituent elements, and can be formed as having a uniform and dense film quality. Such a thermal spray coating is particularly preferable because it has enhanced plasma erosion resistance.

In another aspect, the techniques disclosed herein provide a method of forming a thermal spray coating by spraying any of the above-mentioned thermal spraying slurries to form a thermal spray coating. As a result, a homogeneous and dense thermal spray coating having excellent plasma erosion resistance can be obtained.

In a preferred embodiment of the method for forming a thermal spray coating disclosed herein, a thermal spraying slurry containing water as the dispersion medium is sprayed with a high-speed frame to form a thermal spray coating. As a result, it is possible to form a sprayed coating having a composition close to that of the sprayed particles while suppressing the oxidation of the sprayed particles. As a result, a thermal spray coating having excellent plasma erosion resistance can be formed.

In a preferred embodiment of the method for forming a thermal spray coating disclosed herein, a thermal spraying slurry containing an organic solvent as the dispersion medium is plasma-sprayed to form a thermal spray coating. As a result, thermal spraying at a relatively low temperature and high speed becomes possible, and a dense thermal spray coating can be formed while suppressing oxidation and alteration of the thermal spray particles. As a result, a thermal spray coating having excellent plasma erosion resistance can be formed.

In a preferred embodiment of the method for forming a thermal spray coating disclosed herein, the thermal spraying slurry is supplied to a thermal spraying apparatus by an axial feed method. As a result, since the thermal sprayed particles in the slurry are charged into the thermal spraying heat source in the axial direction, more thermal sprayed particles can be contributed to the film formation, and the thermal sprayed film can be formed with high thermal spraying efficiency.
The "axial feed method" is a method of supplying a thermal spraying slurry from the center of a thermal spraying heat source (for example, a plasma arc or a combustion flame) in the generation direction of the thermal spraying heat source or the axial direction of the torch nozzle.

In a preferred embodiment of the method for forming a thermal spray coating disclosed herein, the thermal spraying slurry is used with two feeders, and the fluctuation periods of the supply amounts of the thermal spraying slurries from the two feeders are in opposite phases to each other. Including supplying to the thermal spraying device in this way. According to this, it is possible to further suppress the agglomeration and sedimentation of the sprayed particles having a relatively large average particle size in the slurry, and to supply the slurry at a substantially constant ratio evenly. This is preferable because a sprayed coating with little variation can be formed in the coating structure.

In a preferred embodiment of the method for forming a thermal spray coating disclosed herein, the thermal spraying slurry is sent out from a feeder, temporarily stored in a tank immediately before the thermal spraying apparatus, and the thermal spraying slurry in the tank is stored by free fall. Includes feeding to thermal spraying equipment. According to this, the state of the thermal spraying slurry can be adjusted in the tank immediately before the thermal spraying apparatus, and it is possible to suppress the agglomeration and sedimentation of the thermal sprayed particles having a relatively large average particle size in the slurry, and the thermal spraying slurry. Can be supplied evenly at a substantially constant ratio. This is also preferable because it is possible to form a thermal sprayed film with little variation in the film structure.

A preferred embodiment of the method for forming a thermal spray coating disclosed herein includes supplying a thermal spraying slurry to a thermal spraying apparatus via a conductive tube. According to this, the generation of static electricity is suppressed in the spraying slurry flowing in the conductive tube, and the supply amount of the sprayed particles is less likely to fluctuate, which is preferable.

Hereinafter, preferred embodiments of the present invention will be described. Matters other than those specifically mentioned in the present specification and necessary for the implementation of the present invention include teachings regarding the implementation of the invention described in the present specification and common general knowledge at the time of filing in the art. It can be understood and implemented by those skilled in the art based on the above.

(Slurry for thermal spraying)
The thermal spraying slurry disclosed herein can contain thermal spray particles composed of a compound containing yttrium (Y) and a halogen element (X) as constituent elements, and a dispersion medium. This thermal spraying slurry is prepared, for example, by mixing thermal spray particles with a dispersion medium. Mixing may be carried out using a vane stirrer, homogenizer or mixer.

The thermal spraying particles contained in the thermal spraying slurry are composed of a compound containing yttrium (Y) and a halogen element (X) as constituent elements. Such a compound can be, for example, a halide of yttrium (Y). Typically, yttrium fluoride (eg, yttrium fluoride (YF ₃ )), chloride (eg, yttrium chloride (YCl ₃ )), bromide (eg, yttrium bromide (YBr ₃ )), yttrium (eg, yttrium iodide). For example, yttrium iodide (YI ₃ )) and the like can be mentioned.

Further, the compound containing yttrium (Y) and a halogen element (X) is not limited to a binary compound, and may be a ternary or higher compound containing any other element. The ternary or higher compound is preferably an oxyhalide of yttrium containing oxygen (O) as a constituent element, for example. Examples of the yttrium oxyhalide include yttrium oxyfluoride, yttrium oxychloride, yttrium oxy bromide, and yttrium oxyiodide. Of course, the compound containing yttrium (Y) and the halogen element (X) can contain any element other than oxygen (O). Any one of such yttrium oxyhalides may be used alone, or two or more thereof may be used in combination.

The ratio of yttrium (Y), oxygen (O) and halogen element (X) constituting the yttrium oxyhalide is not particularly limited. For example, the molar ratio (X / Y) of the halogen element to yttrium is not particularly limited. As a preferred example, the molar ratio (X / Y) may be, for example, 1 and is preferably greater than 1. Specifically, for example, it is more preferably 1.1 or more, and for example, 1.2 or more, and further preferably 1.3 or more. The upper limit of the molar ratio (X / Y) is not particularly limited and may be, for example, 3 or less. Among them, the molar ratio (X / Y) of the halogen element to yttrium is more preferably 2 or less, and further preferably 1.4 or less (less than 1.4). As a more preferable example of the molar ratio (X / Y), it is exemplified that the molar ratio is 1.3 or more and 1.39 or less (for example, 1.32 or more and 1.36 or less). As described above, a high ratio of the halogen element to yttrium is preferable because the resistance to the halogen-based plasma is high.

Further, the molar ratio (O / Y) of the oxygen element to yttrium is not particularly limited. As a preferred example, the molar ratio (O / Y) may be 1, preferably less than 1. Specifically, for example, it is more preferably 0.9 or less, and more preferably 0.88 or less, and further preferably 0.86 or less. The lower limit of the molar ratio (O / Y) is also not particularly limited, and may be, for example, 0.1 or more. Among them, as a more preferable example of the molar ratio (O / Y) of the oxygen element to yttrium, it is preferably more than 0.8 and less than 0.85 (preferably 0.81 or more and 0.84 or less). In this way, the ratio of oxygen element to yttrium is less preferred for formation of oxide of yttrium in the thermal spray coating in the oxidation in the thermal spray (e.g., Y _{2 O 3)} is suppressed.

That is, the yttrium oxyhalide is represented by, for example, the general formula; Y ₁ O _m1 X _m2 (for example, 0.1 ≦ m1 ≦ 1.2, 0.1 ≦ m2 ≦ 3), and Y and O. The ratio with X may be any compound. The yttrium oxyhalide is preferably 0.81 <m1 <1, more preferably 0.81 <m1 <0.85, for example 0.84 ≦ m1 ≦ 0.82). Further, 1 <m2 <1.4 is preferable, and 1.29 <m2 <1.4, for example, 1.3 ≦ m2 ≦ 1.38.

As a preferred embodiment, a case where the halogen element is fluorine (F) and the yttrium oxyhalide is yttrium oxyfluoride (YOF) will be described. The yttrium oxyfluoride may be, for example, a compound that is thermodynamically relatively stable and has a chemical composition of 1: 1: 1 in the ratio of yttrium, oxygen, and halogen element expressed as YOF. Further, the general formula; Y ₁ O _1-n F _{1 + 2n} (in the formula, n satisfies, for example, 0.12 ≦ n ≦ 0.22), Y ₅ O ₄ F ₇ , Y ₆ O ₅ It may be F ₈ , Y ₇ O ₆ F ₉ , Y ₁₇ O ₁₄ F _23, or the like. _{In particular, Y 6} O ₅ F ₈ , Y ₁₇ O ₁₄ F _23, etc., whose molar ratios (O / Y) and (X / Y) are in the above-mentioned more preferable ranges, have excellent plasma erosion resistance and are more precise. It is preferable because it can form a high-hardness sprayed coating. Such an yttrium oxyhalide may be composed of a single phase of any one compound, or a mixed phase in which any two or more compounds are combined, a solid solution, any one of the compounds, or any of these. It may be composed of a mixture or the like.

The yttrium halide and the yttrium oxyhalide have been described by taking the case where the halogen element is fluorine as an example. However, even when the halogen element is other than fluorine, these compounds can have the same or similar crystal structure and have similar characteristics. Therefore, those skilled in the art can use one of the fluorine (F) described above. It can be understood that the same action can be obtained for a compound in which a part or all of the compound is replaced with an arbitrary halogen element.
The detailed composition of the yttrium halide and / or the yttrium oxyhalide contained in the sprayed particles and the ratio thereof are not particularly limited. For example, all of the sprayed particles may be yttrium halides, all may be yttrium oxyhalides, or a mixture thereof in any proportion.

From the viewpoint that a thermal spray coating having excellent plasma erosion resistance can be formed, the thermal spray particles preferably contain an yttrium oxyhalide. Such yttrium oxyhalide is preferably contained in the sprayed particles in a high proportion of 77% by mass or more. Yttrium oxyhalide is more excellent in plasma erosion resistance than _{yttria (Y 2} O ₃ ), which is known as a material having high plasma erosion resistance. Such an yttrium oxyhalide greatly contributes to the improvement of plasma erosion resistance even if it is contained in a small amount, but it is preferable that it is contained in a large amount as described above because it can exhibit extremely good plasma resistance. The ratio of the yttrium oxyhalide is more preferably 80% by mass or more (exceeding 80% by mass), further preferably 85% by mass or more (exceeding 85% by mass), and 90% by mass or more (90% by mass). (Excess) is even more preferable, and 95% by mass or more (95% by mass or more) is even more preferable. For example, substantially 100% by weight (all except unavoidable impurities) is particularly preferred. By containing the yttrium oxyhalide in a high proportion as described above, the sprayed particles are allowed to contain other substances that are more likely to be a particle source.

When the sprayed particles contain a yttrium oxyhalide, it may be preferable that all the sprayed particles are yttrium oxyhalides. However, for the yttrium oxyhalide having a composition that is relatively easily oxidized (for example, Y ₁ O ₁ F ₁ ), it is preferable that the yttrium halide is contained in a proportion of 23% by mass or less, for example. The yttrium halide contained in the thermal spray particles can be oxidized by thermal spraying to form an oxide of a rare earth element in the thermal spray coating. For example, yttrium fluoride can be oxidized by thermal spraying to form yttrium oxide in the thermal spray coating. Yttrium oxyhalides (eg, Y ₁ O ₁ F ₁ ) can also be oxidized by thermal spraying to form oxides of rare earth elements in the thermal spray coating. However, when the yttrium oxyhalide and a small amount of the yttrium halide coexist, the oxidation of the yttrium oxyhalide may be suppressed by the yttrium halide, which is preferable. However, the excessive content of the yttrium halide is not preferable because it can form a particle source as described above, and if it is contained in excess of 23% by mass, the plasma erosion resistance is lowered. From this point of view, the content ratio of the halide of yttrium is preferably 20% by mass or less, more preferably 15% by mass or less, and further preferably 10% by mass or less, for example, 5% by mass or less. preferable. In a more preferred embodiment of the thermal spraying material disclosed herein, it may also be substantially free of yttrium halides (eg yttrium fluoride).

Furthermore, spray particles, to more capable high to express plasma resistance when forming the sprayed coating, an oxide of yttrium (yttrium oxide: Y 2 _{O 3)} is preferably configured to substantially free of components .. Yttrium oxide contained in the sprayed particles can exist as yttrium oxide as it is in the sprayed coating by thermal spraying. As described above, this yttrium oxide has a significantly lower plasma resistance than the yttrium halide and the like. Therefore, the portion containing yttrium oxide tends to form a brittle altered layer when exposed to a plasma environment, and the altered layer becomes very fine particles and easily desorbs. Then, these fine particles may be deposited on the semiconductor substrate as particles. Therefore, it is preferable to eliminate the inclusion of yttrium oxide, which can be a particle source, in the thermal spraying slurry disclosed herein.

In the present specification, "substantially not contained" means that the content ratio of the component (yttrium oxide in this case) is 5% by mass or less, preferably 3% by mass or less, for example, 1% by mass or less. means. Such a configuration can also be grasped by, for example, when the thermal spraying material is subjected to X-ray diffraction analysis, a diffraction peak based on the component is not detected.

When the sprayed particles contain a plurality of yttrium halides and / or yttrium oxyhalides having a composition of a plurality (for example, a; a ≧ 2 when a natural number is taken), the content ratio of the compound of each composition is adjusted by the following method. It can be measured and calculated. First, the composition of the compound constituting the sprayed particles is specified by X-ray diffraction analysis. At this time, the yttrium oxyhalide is identified up to its valence (elemental ratio).

Then, for example, when one type of yttrium oxyhalide is present in _{the thermal spraying material and the rest is YF 3} , the oxygen content of the thermal spraying material is, for example, an oxygen / nitrogen / hydrogen analyzer (for example, manufactured by LECO). , ONH836), and the content of yttrium oxyhalide can be quantified from the obtained oxygen concentration.
When two or more types of yttrium oxyhalides are present or compounds containing oxygen such as yttrium oxide are mixed, the ratio of each compound can be quantified by a calibration curve method, for example. Specifically, several types of samples with different content ratios of each compound are prepared, X-ray diffraction analysis is performed on each sample, and a calibration curve showing the relationship between the main peak intensity and the content of each compound is created. do. Then, based on this calibration curve, the content is quantified from the main peak intensity of the yttrium oxyhalide of XRD of the thermal spraying material to be measured.

Regarding the molar ratio (X / Y) and the molar ratio (O / Y) of the above-mentioned yttrium oxyhalide, the molar ratio (Xa / Ya) and the molar ratio (Oa / Ya) are calculated for each composition. , The molar ratio (Xa / Ya) and the molar ratio (Oa / Ya) are multiplied by the abundance ratio of the composition and summed (weighted sum) to obtain the molar amount of the yttrium oxyhalide as a whole in the sprayed particles. Ratios (X / Y) and molar ratios (O / Y) can be obtained.

The sprayed particles can typically be prepared in the form of powder. Such a powder may be composed of granulated particles obtained by granulating finer primary particles, or may be composed mainly of aggregates of primary particles (may include a form of agglomeration). There may be. More preferably, it is a powder composed of an aggregate of primary particles. From the viewpoint that the spraying efficiency is enhanced when the slurry is formed, for example, the average particle size of the sprayed particles is not particularly limited as long as it is about 10 μm or less, and the lower limit of the average particle size is not particularly limited. The average particle size of the sprayed particles can be, for example, 6 μm or less, preferably 4 μm or less, and more preferably about 3 μm or less. The lower limit of the average particle size is also not particularly limited, and when the fluidity of the thermal spraying material is taken into consideration, it can be, for example, 1 nm or more, preferably 10 nm or more.

Normally, for example, when fine sprayed particles having an average particle size of about 10 μm or less are used for spraying in the form of powder, the fluidity decreases as the specific surface area increases. Then, the supply of the sprayed particles to the sprayed device is inferior, and the sprayed particles adhere to the supply path and are difficult to be supplied to the sprayed device, which may reduce the ability to form the thermal spray coating. Further, such sprayed particles are repelled by the sprayed frame or the jet stream due to their small mass, and it may be difficult to fly them to the base material properly. On the other hand, in the spraying slurry disclosed here, for example, even if the sprayed particles have an average particle diameter of 10 μm or less, they are prepared as a slurry in consideration of the supplyability to the spraying apparatus, so that the slurry is supplied. Adhesion to the route or the like is suppressed, and the film forming ability can be maintained high. In addition, since it is supplied to the frame or jet stream in the state of slurry, it is possible to ride on the flow without being repelled by the frame or jet, and the dispersion medium is removed during flight, so thermal spraying efficiency is improved. It can be maintained higher to form a sprayed coating.

The average particle size of the sprayed particles is the volume measured using a laser diffraction / scattering type particle size distribution measuring device (LA-950, manufactured by Horiba Seisakusho Co., Ltd.) for particles having an average particle size of about 1 μm or more. An integrated 50% particle size (D ₅₀ ) in the standard particle size distribution can be adopted. _{At the same time as the measurement of the average particle size, the integrated 3% particle size (D 3} ), which is the particle size of the particles 3% from the small particle size side in the volume-based particle size distribution of the sprayed particles, and 97 from the small particle size side. _{The cumulative 97% particle size (D 97} ), which is the particle size of the% particle, can be calculated.
For particles having an average particle diameter of less than about 1 μm, a sphere-equivalent diameter calculated based on the specific surface area can be adopted. The specific surface area, for example, a specific surface area measuring apparatus (Micromeritics Inc., FlowSorbII 2300,) used, the gas adsorption amount of _{N 2} or the like which is measured by the continuous flow method, a value calculated by BET1 point method be able to. The critical value of the average particle size to which each measurement method is applied is not strictly defined, and can be changed according to the accuracy of the analyzer used.

(Dispersion medium)
As the dispersion medium, either an aqueous dispersion medium or a non-aqueous dispersion medium can be adopted.
As the aqueous dispersion medium, water or a mixture of water and a water-soluble organic solvent (mixed aqueous solution) can be used. As the water, tap water, ion-exchanged water (deionized water), distilled water, pure water and the like can be used. As the organic solvent other than water constituting this mixed aqueous solution, one or more organic solvents (for example, lower alcohols having 1 to 4 carbon atoms or lower ketones) that can be mixed uniformly with water are appropriately selected. Can be used. For example, organic solvents such as methanol, ethanol, n-propyl alcohol and isopropyl alcohol are suitable examples. As the aqueous solvent, for example, it is preferable to use a mixed aqueous solution in which 80% by mass or more (more preferably 90% by mass or more, still more preferably 95% by mass or more) of the aqueous solvent is water. A particularly preferred example may be an aqueous solvent that is substantially composed of water (eg, tap water, distilled water, pure water, purified water).

The non-aqueous solvent typically includes an organic solvent that does not contain water. The organic solvent is not particularly limited, and for example, alcohols such as methanol, ethanol, n-propyl alcohol and isopropyl alcohol, and one kind of organic solvent such as toluene, hexane and kerosene may be used alone or in combination of two or more. It can be used.
The type and composition of the dispersion medium to be used can be appropriately selected depending on, for example, the thermal spraying method of the thermal spraying slurry. That is, for example, when the thermal spraying slurry is sprayed by the high-speed flame spraying method, either an aqueous solvent or a non-aqueous solvent may be used. The use of an aqueous dispersion medium is advantageous in that the surface roughness of the obtained sprayed coating is improved (smoothened) as compared with the case of using a non-aqueous dispersion medium. The use of a non-aqueous dispersion medium is advantageous in that the porosity of the obtained sprayed coating is reduced as compared with the case of using an aqueous dispersion medium.

The type of dispersion medium to be used can be appropriately selected according to the solubility of the sprayed particles and the spraying method of the spraying slurry. For example, when the spraying slurry is sprayed with a high-speed frame, it is preferable to use an aqueous dispersion medium. When the spraying slurry is plasma sprayed, it is preferable to use a non-aqueous dispersion medium. However, in the case of plasma spraying, an aqueous dispersion medium can be used instead.

The content of the sprayed particles in the sprayed slurry, that is, the solid content concentration is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 30% by mass or more. In this case, it becomes easy to improve the thickness of the thermal spray coating produced from the thermal spraying slurry per unit time, that is, the thermal spraying efficiency.
The content of the sprayed particles in the sprayed slurry is also preferably 70% by mass or less (less than 70% by mass), more preferably 60% by mass or less, still more preferably 50% by mass or less. In this case, it becomes easy to obtain a thermal spraying slurry having a required fluidity suitable for good supply to the thermal spraying apparatus, that is, a thermal spraying slurry having a sufficient fluidity for forming a thermal spray coating.

The viscosity of the spraying slurry is preferably 300 mPa · s or less, more preferably 100 mPa · s or less, still more preferably 50 mPa · s or less, and most preferably 30 mPa · s or less. As the viscosity of the thermal spraying slurry decreases, it becomes easier to obtain a thermal spraying slurry having sufficient fluidity for forming the thermal spray coating, which is preferable.
The viscosity of the spraying slurry is the viscosity at room temperature (25 ° C.) measured using a rotary viscometer. As the viscosity, for example, a value measured using a Brookfield type rotational viscometer (for example, Viscotester VT-03F manufactured by Rion Co., Ltd.) can be adopted.

One aspect of the fluidity of the sprayed slurry can be evaluated by the viscosity as described above, and the viscosity may depend on the density (composition), morphology, etc. of the sprayed particles of the sprayed slurry. Therefore, the composition of the thermal spraying slurry disclosed herein can be adjusted so as to further enhance the plasma erosion resistance of the obtained thermal spray coating, depending on the composition and morphology of the thermal spray particles used for thermal spraying.

For example, when the average particle size of the sprayed particles is less than about 200 nm, the sprayed particles are less likely to settle in the sprayed slurry due to the increase in the specific surface area, and the dispersion stability is improved. From this point of view, the average particle size of the sprayed particles is preferably less than 200 nm, preferably less than 150 nm. However, if the average particle size is too small, the supply of the sprayed particles to the spraying device is significantly reduced. Further, the smaller the average particle size, the higher the viscosity tends to be. Therefore, as described above, the average particle size of the sprayed particles is preferably 1 nm or more, more preferably 10 nm or more. At this time, the solid content concentration is preferably 50% by mass or less, more preferably 30% by mass or less, for example, 25% by mass or less. The solid content concentration is preferably 10% by mass or more, more preferably 20% by mass or more.

Further, when the average particle size of the sprayed particles used is 200 nm or more, the sprayed particles are easily settled by gravity in the sprayed slurry to cause precipitation. Therefore, it is preferable that the sprayed particles having an average particle size of 200 nm or more are easily dispersed in the sprayed slurry during use. As such means, (1) to improve the dispersion stability of the sprayed particles in the spraying slurry, (2) to facilitate the redispersion of the precipitated sprayed particles, and the like are considered.

(Dispersant)
The spraying slurry may further contain a dispersant, if necessary. Here, the dispersant refers to a compound capable of improving the dispersion stability of the sprayed particles in the sprayed slurry. Such a dispersant may be, for example, essentially a compound that acts on the sprayed particles or a compound that acts on the dispersion medium. Further, for example, it may be a compound that improves the wettability of the surface of the sprayed particles by acting on the sprayed particles or a dispersion medium, or it may be a compound that dissolves the sprayed particles, or it has been dissolved. It may be a compound that suppresses / inhibits the reaggregation of sprayed particles.

The dispersant can be appropriately selected from an aqueous dispersant and a non-aqueous dispersant according to the above-mentioned dispersion medium. Further, the dispersant may be any of a high molecular weight dispersant, a surfactant type dispersant (also referred to as a low molecular weight dispersant) or an inorganic type dispersant, and these may be anionic or cationic. It may be either sex or nonionic. That is, it may have at least one functional group of an anionic group, a cationic group and a nonionic group in the molecular structure of the dispersant.

Examples of the polymer-type dispersant include a dispersant composed of a polycarboxylic acid-based compound such as a sodium polycarboxylic acid salt, an ammonium polycarboxylic acid salt, and a polycarboxylic acid-based polymer, and a sodium polystyrene sulfonate salt as an aqueous dispersant. , Polystyrene sulfonic acid ammonium salt, Polyisoprene sulfonic acid sodium salt, Polyisoprene sulfonic acid ammonium salt, Naphthalene sulfonic acid sodium salt, Naphthalene sulfonic acid ammonium salt, Naphthalene sulfonic acid formalin condensate sodium salt, Naphthalene sulfonic acid formalin condensate Examples thereof include a dispersant composed of a sulfonic acid-based compound such as an ammonium salt, a dispersant composed of a polyethylene glycol compound, and the like. Further, as a non-aqueous dispersant, a dispersant composed of an acrylic compound such as polyacrylic acid salt, polymethacrylic acid salt, polyacrylamide, polymethacrylamide, etc., and a polycarboxylic acid having an alkyl ester bond as part of the polycarboxylic acid. Examples thereof include a dispersant composed of an acid partial alkyl ester compound, a dispersant composed of a polyether compound, and a dispersant composed of a polyalkylene polyamine compound.

As is clear from this description, for example, the concept of "polycarboxylic acid-based compound" as used herein includes the polycarboxylic acid-based compound and a salt thereof. The same applies to other compounds.
Further, for convenience, even if the compound is classified as either an aqueous dispersant or a non-aqueous dispersant, a compound used as the other non-aqueous dispersant or an aqueous dispersant may also be used depending on its detailed chemical structure and usage pattern. could be.

Examples of surfactant-type dispersants (also referred to as low-molecular-weight dispersants) include, as an aqueous dispersant, a dispersant composed of an alkylsulfonic acid-based compound, a dispersant composed of a quaternary ammonium compound, and an alkylene oxide compound. Dispersants and the like can be raised. Examples of the non-aqueous dispersant include a dispersant composed of a polyhydric alcohol ester compound, a dispersant composed of an alkyl polyamine compound, and a dispersant composed of an imidazoline compound such as alkyl imidazoline.

Examples of inorganic dispersants include aqueous dispersants such as orthophosphates, metaphosphates, polyphosphates, pyrophosphates, tripolyphosphates, hexametaphosphates, and organic phosphates. , Iron sulfates such as ferric sulfate, ferrous sulfate, ferrous chloride, and ferrous chloride, aluminum salts such as aluminum sulfate, polyaluminum chloride, and sodium aluminate, calcium sulfate, calcium hydroxide, and Calcium salts such as dicalcium phosphate and the like can be mentioned.

Any one of the above dispersants may be used alone, or two or more of them may be used in combination. In the technique disclosed herein, as a specific example, it is preferable to use an alkylimidazoline compound-based dispersant and a dispersant composed of a polyacrylic acid compound in combination. The content of the dispersant is not necessarily limited because it depends on the composition (physical properties) of the sprayed particles, but is typically 0.01 to 2 when the mass of the sprayed particles is 100% by mass. The range of mass% can be used as a rough guide.

(Coagulant)
The spraying slurry may further contain a flocculant, if necessary. Here, the coagulant refers to a compound capable of agglomerating the sprayed particles in the sprayed slurry. Typically, it refers to a compound capable of softly flocculating sprayed particles in a sprayed slurry. Although it depends on the physical properties of the sprayed particles, when the spraying slurry contains a coagulant (including a redispersibility improver, an anti-caking agent, etc.), the sprayed particles have a coagulant interposed between the sprayed particles. By the precipitation of the precipitated particles, the aggregation of the precipitated sprayed particles is suppressed and the redispersibility is improved. That is, the precipitated sprayed particles can prevent individual particles from densely aggregating (possibly condensing) (also referred to as caking or hard caking) even when they are precipitated. It is particularly preferable to include this flocculant in a spraying slurry containing sprayed particles having an average particle size of 200 nm or more and easily settling. That is, since the precipitated sprayed particles are easily redispersed by an operation such as stirring, the operation for redispersion becomes simple. The flocculant may be any of an aluminum compound, an iron compound, a phosphoric acid compound, and an organic compound. Examples of aluminum-based compounds include aluminum sulfate (also referred to as aluminum sulfate band), aluminum chloride, and polyaluminum chloride (also referred to as PAC and PACl). Examples of iron-based compounds include ferric chloride, ferric polysulfate and the like. Examples of phosphoric acid compounds include sodium pyrophosphate and the like. Examples of organic compounds include organic acids such as malic acid, succinic acid, citric acid, maleic acid, maleic anhydride, diallyldimethylammonium chloride polymer, lauryltrimethylammonium chloride, naphthalenesulfonic acid condensate, triisopropylnaphthalenesulfonic acid. Examples thereof include sodium, sodium polystyrene sulfonate, isobutylene-maleic acid copolymer, carboxyvinyl polymer, and the like.

(Viscosity adjuster)
The spraying slurry may further contain a viscosity modifier, if necessary. Here, the viscosity modifier refers to a compound capable of lowering or increasing the viscosity of the thermal spraying slurry. By appropriately adjusting the viscosity of the thermal spraying slurry, it is possible to suppress a decrease in the fluidity of the thermal spraying slurry even when the content of the thermal spraying particles in the thermal spraying slurry is relatively high. Examples of compounds that can be used as a viscosity modifier include nonionic polymers such as polyethers such as polyethylene glycol and cellulose derivatives such as carboxymethyl cellulose (CMC) and hydroxyethyl cellulose (HEC).

(Defoamer)
The spraying slurry may further contain an antifoaming agent, if necessary. Here, the defoaming agent is a compound capable of preventing bubbles from being generated in the thermal spraying slurry during the production or spraying of the thermal spraying slurry, or a compound capable of eliminating bubbles generated in the thermal spraying slurry. say. Examples of the defoaming agent include silicone oil, silicone emulsion-based defoaming agent, polyether-based defoaming agent, fatty acid ester-based defoaming agent, and the like.

(Preservatives, fungicides)
The spraying slurry may further contain a preservative or an antifungal agent, if necessary. Examples of preservatives or fungicides include isothiazolin-based compounds, azole-based compounds, propylene glycol and the like.

When the above additives such as dispersant, flocculant, viscosity modifier, defoamer, preservative and fungicide are used, any one of them may be used alone, or two or more thereof may be used. It may be used in combination. These additives may be added to the dispersion medium at the same timing as the thermal spray particles when preparing the thermal spraying slurry, or may be added at a different timing. Although not strictly limited, when these additives are added, the sum of the additives typically ranges from 0.01 to 10% by weight with the mass of the sprayed particles as 100% by weight. It is exemplified that the particles are added so as to become.
In addition, the compounds as various additives exemplified above may exhibit a function as another additive in addition to the action as the main additive use. In other words, for example, compounds of the same type or composition may act as two or more different additives.

The pH of the spraying slurry is preferably 6 or more, more preferably 7 or more, still more preferably 8 or more. In this case, it becomes easy to improve the storage stability of the spraying slurry. The pH of the spraying slurry is also preferably 11 or less, more preferably 10.5 or less, still more preferably 10 or less. In this case, it becomes easy to improve the dispersion stability of the sprayed particles in the sprayed slurry. The spraying slurry may contain a pH adjusting agent such as various known acids, bases, or salts thereof for the purpose of adjusting the pH. Specific examples of the pH adjuster include organic acids such as carboxylic acid, organic phosphonic acid and organic sulfonic acid, inorganic acids such as phosphoric acid, phosphite, sulfuric acid, nitrate, hydrochloric acid, boric acid and carbonic acid, and tetra. Organic bases such as methylammonium hydroxide, trimethanolamine and monoethanolamine, inorganic bases such as potassium hydroxide, sodium hydroxide and ammonia, or salts thereof are preferably used.

The pH of the spraying slurry is determined by using a glass electrode type pH meter (for example, a tabletop pH meter F-72 manufactured by Horiba Seisakusho Co., Ltd.) and a pH standard solution (for example, a phthalate pH standard solution (for example). Using JIS Z8802 using a pH standard solution (pH: 4.005 / 25 ° C.), a neutral phosphate pH standard solution (pH: 6.865 / 25 ° C.), a carbonate pH standard solution (pH: 10.12 / 25 ° C.), etc. : A value measured according to 2011 can be adopted.

The sedimentation rate of the sprayed particles in the sprayed slurry can be used as an index showing the degree of dispersion stability of the sprayed particles in the sprayed slurry. The sedimentation rate is preferably 30 μm / sec or more, more preferably 35 μm / sec or more, and further preferably 40 μm / sec or more. The thermal spray particles in the thermal spray slurry may remain dispersed without settling.
As the settling rate of the sprayed particles in the spraying slurry, a value measured according to the liquid phase centrifugal settling method (JIS Z8823-1: 2001) can be adopted for all the sprayed particles. For the sedimentation speed, for example, a value measured at a rotation speed of 920 rpm (100 G) using a particle size distribution / dispersion stability analyzer (LUMiSizer 610 manufactured by LUM GmbH) by a centrifugal sedimentation / light transmission method can be adopted. can.

The zeta potential of the sprayed particles in the spraying slurry preferably has an absolute value of 10 mV or more, more preferably 25 mV or more, and further preferably 40 mV or more. In this case, since the sprayed particles strongly repel each other electrically, it becomes easy to improve the dispersion stability of the sprayed particles in the sprayed slurry. The upper limit of the absolute value of the zeta potential is not particularly limited, but for example, about 150 mV can be used as a guide.
The value of the zeta potential of the thermal spray particles in the thermal spraying slurry is a value measured by supplying the thermal spraying slurry to the zeta potential measuring device as it is (without pretreatment or the like) and circulating the slurry in the device. As the zeta potential in the present specification, the value obtained by using the ultrasonic particle size distribution / zeta potential measuring device (manufactured by Dispersion Technology Co., Ltd., DT-1200) is adopted.

In addition, the thermal sprayed particles may aggregate in the thermal spraying slurry to form agglomerated particles (here, referred to as "secondary particles"). In the sprayed slurry disclosed herein, it is preferable that the sprayed particles suppress the formation of secondary particles. Whether or not the sprayed particles form secondary particles is determined by measuring the average particle size of the sprayed particles in the slurry and using that value as the average of the sprayed particles (dry powder) prepared for preparing the sprayed slurry. It can be grasped by comparing with the particle size. For example, if the average particle size becomes 1.5 times or more before and after the slurry preparation, it can be determined that the sprayed particles form secondary particles over almost the entire area. On the other hand, if the average particle size is less than 1.5 times (preferably 1.3 times or less) and there is not much change before and after the slurry preparation, it is judged that the formation of secondary particles is suppressed in the sprayed particles. Can be done.
The average particle size of the sprayed particles in the slurry can be measured by using various particle size distribution measuring devices in the same manner as the average particle size of the sprayed particles used as a raw material. _{In the present specification, for example, an integrated 50% particle size (D 50} ) in a volume-based particle size distribution measured using a laser diffraction / scattering particle size distribution measuring device (LA-950, manufactured by HORIBA, Ltd.). Is adopted. _{At the same time as the measurement of the average particle size, the integrated 3% particle size (D 3} ), which is the particle size of the particles 3% from the small particle size side in the volume-based particle size distribution of the sprayed particles, and the small particle size side _{By calculating the integrated 97% particle size (D 97} ), which is the particle size of the 97th particle, the variation in particle size (state of formation of secondary particles) can be grasped.

From the viewpoint of improving the redispersibility of the sprayed particles, it may be effective to adjust the particle size (variation of particle size) of the sprayed particles in the slurry. In particular, increasing the proportion of smaller particles can be effective. Therefore, for example, the ratio (D ₃ / D ₅₀ ) of the integrated 3% particle size (D ₃ ) to the average particle size (D ₅₀ ) of the sprayed particles in the slurry is preferably 0.05 or more, and 0. It is preferably 1 or more, and more preferably 0.15 or more.
If coarse particles (which can be agglomerated particles) are present in the sprayed particles in the slurry, the plasma erosion resistance of the sprayed coating can be significantly reduced at the periphery of the sprayed particles. Therefore, for example, the ratio (D ₉₇ / D ₅₀ ) of the integrated 97% particle size (D ₉₇ ) to the average particle size (D ₅₀ ) of the sprayed particles in the slurry is preferably 7 or less, and is preferably 6 or less. It is more preferable, and it is particularly preferable that it is 5 or less.

The above-mentioned spraying slurry may contain sprayed particles having good dispersibility or may be prepared as a slurry having good redispersibility. Therefore, for example, this thermal spraying slurry can be provided as a whole packaged into two or more configurations, and can be integrally used for thermal spraying (actual use). For example, this thermal spraying slurry contains, from the state in which the thermal spraying particles are precipitated, a component portion (typically, a supernatant portion) that does not contain the thermal spraying particles or has a lower content, and all the thermal spraying particles. It can be divided into and provided as a component having a higher content (typically, the balance from which the supernatant portion has been removed). Then, in actual use, the divided components can be appropriately mixed and shaken to be used as the above-mentioned thermal spraying slurry. Alternatively, the thermal spraying slurry can be provided by accommodating components other than the dispersion medium in one or more packages separate from the dispersion medium. In this case as well, in actual use, a spraying slurry can be prepared by mixing a component other than the dispersion medium with the dispersion medium. By doing so, the spraying slurry can be easily prepared even immediately before the thermal spraying. It also has the advantage of being easy to store until it is used for thermal spraying.

(Method of forming a thermal spray coating)
(Base material)
In the method for forming a thermal spray coating disclosed herein, the target substrate on which the thermal spray coating is formed by thermal spraying is not particularly limited. For example, a base material made of various materials can be used as long as it is a base material made of a material capable of exhibiting desired resistance to such thermal spraying. Examples of such a material include various metals or alloys. Specifically, for example, aluminum, aluminum alloys, iron, steel, copper, copper alloys, nickel, nickel alloys, gold, silver, bismuth, manganese, zinc, zinc alloys and the like are exemplified. Among the widely used metal materials, steel represented by various SUS materials (which may be so-called stainless steel), heat-resistant alloys represented by Inconel, etc., Inver, and Coval, which have a relatively large coefficient of thermal expansion. Examples thereof include low expansion alloys typified by, etc., corrosion resistant alloys typified by hasteroi, and aluminum alloys typified by 1000 series to 7000 series aluminum alloys, which are useful as lightweight structural materials.

(Film formation method)
The thermal spraying slurry disclosed herein can be used as a thermal spraying material for forming a thermal spray coating by being applied to a thermal spraying apparatus based on a known thermal spraying method. As a thermal spraying method for preferably spraying the thermal spraying slurry, for example, adopting a thermal spraying method such as a plasma spraying method or a high-speed frame thermal spraying method is exemplified.
The plasma spraying method is a thermal spraying method that uses a plasma flame as a thermal spraying heat source for softening or melting a thermal spray material. When an arc is generated between the electrodes and the working gas is turned into plasma by the arc, the plasma flow is ejected from the nozzle as a high-temperature and high-speed plasma jet. The plasma spraying method includes a general coating method for obtaining a thermal spray coating by charging a thermal spraying material into the plasma jet, heating and accelerating it, and depositing it on a substrate. The plasma spraying method includes atmospheric plasma spraying (APS) performed in the atmosphere, low pressure plasma spraying (LPS) performed at a pressure lower than atmospheric pressure, and application higher than atmospheric pressure. It may be an embodiment such as high pressure plasma spraying in which plasma spraying is performed in a pressure vessel. According to such plasma spraying, for example, by melting and accelerating the sprayed material with a plasma jet of about 5000 ° C. to 10000 ° C., the sprayed particles collide with the substrate at a speed of about 300 m / s to 600 m / s. Can be deposited.

Further, as the high-speed frame thermal spraying method, for example, an oxygen-supported high-speed frame (HVOF) thermal spraying method, a worm spray thermal spraying method, an air-supported (HVAF) high-speed frame thermal spraying method, and the like can be considered.
The HVOF thermal spraying method is a type of frame thermal spraying method in which a combustion flame obtained by mixing fuel and oxygen and burning them at high pressure is used as a heat source for thermal spraying. By increasing the pressure in the combustion chamber, a high-speed (possibly supersonic) high-temperature gas flow is ejected from the nozzle while being a continuous combustion flame. The HVOF thermal spraying method includes a general coating method for obtaining a thermal spray coating by putting a thermal spraying material into this gas stream, heating and accelerating it, and depositing it on a substrate. According to the HVOF thermal spraying method, for example, by supplying a thermal spraying slurry to a jet of a supersonic combustion flame at 2000 ° C. to 3000 ° C., the dispersion medium is removed from the slurry (combustion or evaporation may be performed. The same shall apply hereinafter. At the same time, the sprayed particles can be softened or melted and collided with the substrate at a high speed of 500 m / s to 1000 m / s for deposition. The fuel used for high-speed flame spraying may be a gas fuel of hydrocarbons such as acetylene, ethylene, propane and propylene, or a liquid fuel such as kerosene and ethanol. Further, it is preferable that the temperature of the supersonic combustion flame is higher as the melting point of the thermal spray material is higher, and from this viewpoint, it is preferable to use gas fuel.

It is also possible to adopt a so-called warm spray thermal spraying method, which is an application of the above HVOF thermal spraying method. The warm spray spraying method is typically a thermal spraying method in which the temperature of the combustion flame is lowered by mixing a cooling gas composed of nitrogen or the like at a temperature of about room temperature with the combustion flame in the above HVOF thermal spraying method. This is a method of forming a thermal spray coating. The thermal spraying material is not limited to a completely melted state, and for example, a material that is partially melted or in a softened state below the melting point can be sprayed. According to this warm spray spraying method, for example, by supplying a spraying slurry to a jet of a supersonic combustion flame at 1000 ° C. to 2000 ° C., the dispersion medium can be removed (combustion or evaporation) from the slurry. The same applies hereinafter), and the sprayed particles can be softened or melted and collided with the substrate at a high speed of 500 m / s to 1000 m / s for deposition.

The HVAF thermal spraying method is a thermal spraying method in which air is used instead of oxygen as a combustion support gas in the above HVOF thermal spraying method. According to the HVAF thermal spraying method, the thermal spraying temperature can be lowered as compared with the HVOF thermal spraying method. For example, by supplying a spraying slurry to a jet of a supersonic combustion flame at 1600 ° C. to 2000 ° C., the dispersion medium is removed from the slurry (combustion or evaporation; the same applies hereinafter) and thermal spraying is performed. The particles can be softened or melted so that the sprayed particles collide with the substrate at a high speed of 500 m / s to 1000 m / s and are deposited.

In the invention disclosed herein, it is preferable to spray the above-mentioned spraying slurry by high-speed frame spraying or plasma spraying because a dense thermal spray coating having excellent plasma erosion resistance can be efficiently formed. Although not particularly limited, when the spraying slurry contains water as a dispersion medium, it is preferable to use high-speed flame spraying. When the dispersion medium contained in the spraying slurry is an organic solvent, it is preferable to use plasma spraying.

The supply of the thermal spraying slurry to the thermal spraying apparatus is not necessarily limited, but the flow rate is preferably 10 mL / min or more and 200 mL / min or less. By setting the supply rate of the thermal spraying slurry to about 10 mL / min or more, the slurry flowing in the thermal spraying slurry supply device (for example, the slurry supply tube) can be in a turbulent state, and the push output of the slurry is increased. Also, it is preferable because the precipitation of the sprayed particles is suppressed. From this point of view, the flow velocity when supplying the spraying slurry is preferably 20 mL / min or more, and more preferably 30 mL / min or more. On the other hand, if the supply rate is too fast, the amount of slurry that can be sprayed by the thermal spraying apparatus may be exceeded, which is not preferable. From this point of view, the flow velocity when supplying the spraying slurry is preferably 200 mL / min or less, preferably 150 mL / min or less, for example, 100 mL / min or less.

Further, it is preferable that the thermal spraying slurry is supplied to the thermal spraying apparatus by an axial feed method, that is, the thermal spraying slurry is supplied in the same direction as the axis of the jet flow generated in the thermal spraying apparatus. For example, when the slurry-like thermal spraying slurry of the present invention is supplied to the thermal spraying apparatus by the axial feed method, the thermal spraying material in the thermal spraying slurry is less likely to adhere to the inside of the thermal spraying apparatus due to the good fluidity of the thermal spraying slurry. It is preferable because a dense thermal spray coating can be efficiently formed.

Further, when the thermal spraying slurry is supplied to the thermal spraying apparatus using a general feeder, it is considered that stable supply becomes difficult because the supply amount fluctuates periodically. If the supply amount of the thermal spraying slurry becomes uneven due to this periodic fluctuation of the supply amount, it becomes difficult to uniformly heat the thermal spray material in the thermal spraying apparatus, and a non-uniform thermal spray coating may be formed. Therefore, in order to stably supply the thermal spraying slurry to the thermal spraying apparatus, a two-stroke method, that is, two feeders are used so that the fluctuation periods of the supply amount of the thermal spraying slurry from both feeders are opposite to each other. You may. Specifically, for example, the supply method may be adjusted so that the cycle is such that when the supply amount from one feeder increases, the supply amount from the other feeder decreases. When the thermal spraying slurry of the present invention is supplied to the thermal spraying apparatus by a two-stroke method, the fluidity of the thermal spraying slurry is good, so that a dense thermal spray coating can be efficiently formed.

As a means for stably supplying the slurry-like thermal spraying material to the thermal spraying device, the slurry sent out from the feeder is temporarily stored in a storage tank provided immediately in front of the thermal spraying device, and naturally dropped from the storage tank. It may be used to supply the slurry to the thermal spraying device, or the slurry in the tank may be forcibly supplied to the thermal spraying device by means such as a pump. When it is forcibly supplied by a means such as a pump, even if the tank and the thermal spraying device are connected by a tube, the thermal spraying material in the slurry is less likely to adhere in the tube, which is preferable. In order to make the distribution state of the components in the thermal spraying slurry in the tank uniform, a means for stirring the thermal spraying slurry in the tank may be provided.

The supply of the thermal spraying slurry to the thermal spraying apparatus is preferably performed via, for example, a metal conductive tube. When the conductive tube is used, the generation of static electricity is suppressed, so that the supply amount of the spraying slurry is less likely to fluctuate. The inner surface of the conductive tube preferably has a surface roughness Ra of 0.2 μm or less.

The thermal spraying distance is preferably set so that the distance from the tip of the nozzle of the thermal spraying device to the base material is 30 mm or more. If the thermal spraying distance is too close, it will not be possible to secure sufficient time to remove the dispersion medium in the thermal spraying slurry, soften and melt the thermal spray particles, or the thermal spray heat source will be close to the thermal spraying base material. Is not preferable because it may be altered or deformed. The thermal spraying distance is preferably about 200 mm or less (preferably 150 mm or less, for example, 100 mm or less). At such a distance, the sufficiently heated sprayed particles can reach the base material while maintaining the temperature, so that a more dense sprayed film can be obtained. At the time of thermal spraying, it is preferable to cool the base material from the surface opposite to the surface to be sprayed. Such cooling can be water cooling or cooling with an appropriate refrigerant.

(Spray coating)
By the above-mentioned techniques disclosed herein, a thermal spray coating composed of a compound having the same composition as the thermal spray particles and / or a decomposition product thereof is formed. That is, the thermal spray coating may contain a compound containing yttrium (Y) and a halogen element (X) and a compound containing yttrium, oxygen and a halogen element (YOX) as constituent components. Therefore, as described above for the sprayed particles, the sprayed coating may have excellent plasma erosion resistance to halogen-based plasma. The thermal spray coating, for example, based on the XRD diffraction, the ratio of the main peak intensity of yttrium oxide _(Y 2 _{O 3)} is 90% or less (preferably 80% or less, 70% and more preferably less, particularly preferably 60% Hereinafter, it can be formed as, for example, 40% or less). Further, in this sprayed coating, for example, the total ratio of the main peak intensities of the yttrium oxyhalide based on XRD diffraction is 10% or more (preferably 20% or more, more preferably 30% or more, particularly preferably 40%). As described above, for example, 60% or more) can be formed.

Further, as described above, this thermal spray coating can be formed by using a thermal spraying slurry having good supply. Therefore, the thermal sprayed particles maintain a suitable dispersed state and fluidized state in the thermal spraying slurry and are stably supplied to the thermal spraying apparatus to form a homogeneous thermal spray coating. In addition, the sprayed particles can be efficiently supplied to the vicinity of the center of the heat source without being repelled by the frame or jet, and can be sufficiently softened or melted. Therefore, the softened or melted sprayed particles adhere to the substrate and between the particles with good adhesion and adhesion. As a result, a sprayed coating having good homogeneity and adhesiveness is formed.

Hereinafter, some examples of the present invention will be described, but the present invention is not intended to be limited to those shown in such examples.

(Example)
The sprayed particles were mixed with a dispersion medium, and if necessary, a dispersant, a viscosity modifier or a flocculant was further mixed to prepare a spraying slurry of Samples 1-38. Details of each thermal spraying slurry are shown in Table 1.

The "dispersion medium" column in Table 1 indicates the type of dispersion medium used in each thermal spraying slurry. In the same column, "EtOH" indicates ethanol, "iso-PrOH" indicates isopropyl alcohol, and "n-PrOH" indicates normal propyl alcohol. When two or more kinds of dispersion media are described in the column, it indicates that the dispersion medium is a mixed dispersion medium in which each dispersion medium is mixed in the following ratio ratio. The mixing ratio of water and EtOH is 50:50 by mass ratio. The mixing ratio of EtOH, iso-PrOH and n-PrOH is 85: 5: 10 in order by mass ratio.
In the "Types of sprayed particles" column in Table 1, the composition of the sprayed particles used in each sprayed slurry is shown. When two or more compositions are described, it means that the sprayed particles of each composition are mixed particles in the stated ratio (mass%).

In the "Average particle size of sprayed particles" column in Table 1, the average particle size of the sprayed particles used in each sprayed slurry is shown. For the average particle size, the value measured by a laser diffraction / scattering type particle size distribution measuring device is used for the sprayed particles with an average particle size of 1 μm or more, and the specific surface area sphere equivalent diameter is used for the sprayed particles with an average particle size of less than 1 μm. ing.

In the "Sprayed particle content" column in Table 1, the content of the sprayed particles in each sprayed slurry is shown.
In the "Dispersant", "Viscosity adjuster", "Coagulant", "Defoamer", and "Antifungal agent" columns in Table 1, the types of these additives used in each thermal spraying slurry are listed. show.
As the dispersant, the non-ionic surfactant type dispersant (Neugen XL-400, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) is not used for the sample using the aqueous dispersion medium containing water as the dispersion medium. For the sample using the aqueous dispersion medium, a special polycarboxylic acid-based surfactant type dispersant (Homogenol L-18 manufactured by Kao Co., Ltd.) was used. As the viscosity modifier, an anionic specially modified polyvinyl alcohol (PVOH) -based viscosity regulator having a sulfonic acid group (Gosenex L-3266, manufactured by Nippon Synthetic Chemical Co., Ltd.) was used. As the flocculant, an isobutylene-maleic acid copolymer or aluminum sulfate was used. As the defoaming agent, a polyether-type nonionic surfactant was used. As the fungicide, any of hydrogen peroxide solution, sodium hypochlorite, and the fungicide shown as Mixing A was used. "Mixed A" in the column of antifungal agent means "5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, and an aqueous mixture of magnesium salts and 2-. "Blend with bromo-2-nitropropane-1,3-diol". In addition, a hyphen (-) in these columns indicates that each additive is not used.

When the dispersant was used, it was used in an amount such that the content of the dispersant in the spraying slurry was 2% by mass. When the viscosity modifier was used, it was used in an amount such that the content of the viscosity modifier in the spraying slurry was 2% by mass. When a coagulant was used, it was used in an amount such that the content of the coagulant in the spraying slurry was 2% by mass. When the defoaming agent was used, the content of the defoaming agent in the spraying slurry was 0.2% by mass. When the fungicide was used, it was used in an amount such that the content of the fungicide in the spraying slurry was 0.2% by mass (in total amount).

Next, the physical properties of the spraying slurries of Samples 1 to 38 were examined, and the results are shown in Table 2.
The "slurry" column in Table 2 shows the results of evaluating whether or not the thermal spraying slurry could be prepared. "○" in the same column indicates that a predetermined amount of spraying particles were mixed in the dispersion medium and agitated at 400 rpm using a general-purpose rotary blade agitator, and "x" indicates agitation at 400 rpm. Indicates that it could not be done.

In the columns of "pH", "viscosity", "precipitation rate", "zeta potential", "D ₃ ", "D ₅₀ ", and "D ₉₇ " in Table 2, the sprayed slurry or the sprayed particles in the slurry are listed. The results of measuring the measured values of each of the relevant physical properties by the above-mentioned method are shown. Further, in the column of "specific gravity" in Table 2, the result of measuring the specific gravity of the thermal spraying slurry according to the "density and specific gravity measuring method using a specific gravity bottle" specified in 6 of JIS Z 8804: 2012 is shown. rice field. The specific gravity bottle used was one conforming to JIS R 3503: 2007. A hyphen (-) in each column indicates that the measurement has not been performed. Regarding the sprayed slurry having an average particle size of 0.012 μm, the settling speed was not evaluated because the sprayed particles did not settle.

Next, thermal spraying was performed using the thermal spraying slurry of Samples 1 to 38, and the thermal spraying property and the characteristics of the thermal spray coating formed by the thermal spraying were investigated, and the results are shown in Table 4.
A part of the information in Table 1 is shown in the “Preparation of slurry for thermal spraying” column in Table 4.
Among the "film-forming properties" columns in Table 4, the "HVOF thermal spraying" column is the result of evaluating whether or not a thermal spray coating could be obtained when each thermal spraying slurry was HVOF sprayed under the following conditions. Is shown. "○ (good)" in the same column indicates that the thickness of the thermal spray coating formed per pass was 2 μm or more, and “× (bad)” means that it was less than 2 μm or for thermal spraying. "-" Indicates that the slurry could not be supplied, and "-" indicates that the test has not been performed.

<HVOF thermal spraying conditions>
Thermal spraying device: "Top gun" manufactured by GTV
Slurry feeder: GTV acetylene gas flow rate 75L / min
Oxygen gas flow rate 230L / min
Thermal spraying distance: 90 mm
Thermal sprayer moving speed: 100m / min
Slurry supply for thermal spraying: 4.5L / hour

In the "APS thermal spraying" column of the "Film coating property" column in Table 4, whether or not a thermal spray coating could be obtained when each thermal spraying slurry was sprayed with atmospheric pressure plasma (APS) under the following conditions. The result of the evaluation is shown. “○ (Good)” in the same column indicates that the thickness of the sprayed coating formed per pass was 0.5 μm or more, and “× (Defective)” indicates the thickness of the sprayed coating formed. The value was less than 0.5 μm, or the spraying slurry could not be supplied, and “-” indicates that the test was not performed. Note that 1 pass means one thermal spraying operation performed by the thermal spraying device (thermal spraying gun) along the operating direction (scanning direction) of the thermal spraying device or the thermal spraying target (base material).

<APS thermal spraying conditions>
Thermal spraying device: Northwest Mettech “Axial III”
Slurry feeder: Northwest Mettech "M650"
Ar gas flow rate: 81 L / min
Nitrogen gas flow rate: 81 L / min
Hydrogen gas flow rate: 18 L / min
Plasma power: 88kW
Thermal spraying distance: 50 mm
Thermal sprayer moving speed: 240m / min
Slurry supply for thermal spraying: 3L / hour

In both HVOF spraying and APS spraying, a plate material (70 mm × 50 mm × 2.3 mm) made of aluminum alloy (Al6061) is prepared as a base material to be sprayed, and a brown alumina abrasive (A #) is prepared. It was used after being blasted according to 40).
In the column of "X-ray diffraction peak relative intensity of thermal spray coating" in Table 4, the main of each crystal phase detected based on the result of X-ray diffraction (XRD) analysis of the thermal spray coating formed from each thermal spraying slurry. The peak intensity is calculated as a ratio (percentage) of the total main peak intensities of all the detected crystal phases. For the samples in which the thermal spray coating could be formed by both HVOF thermal spraying and APS thermal spraying, the results of analysis of the thermal spray coating formed by APS thermal spraying were shown. The "Y2O3" column is a phase composed of yttrium oxide, the "YF3" column is a phase composed of yttrium fluoride, and the "YOF" column is an yttrium oxyfluoride _{having a chemical composition represented by YOF (Y 1} O ₁ F _1). consisting essentially of the phase, "Y7O8F9" column of the phase consisting of yttrium oxy fluorides chemical composition is represented by _{Y 7 O 6 F 9, "} Y6O5F8" column chemical composition is represented by _Y 6 _O 5 _{F 8} The "Y5O4F7" column of the yttrium oxyfluoride phase shows the relative intensity of the main peak of the yttrium oxyfluoride phase whose _{chemical composition is represented by Y 5} O ₄ F _7.

In addition, in the (F / Y) column and the (O / Y) column of "X-ray diffraction peak relative intensity of the sprayed coating" in Table 4, the yttrium oxyfluorine having the above four compositions is F for the Y element. The result of calculating the ratio of the element (F / Y) and the ratio of the O element to the Y element (O / Y) and calculating the weighted sum of them is shown.

For XRD analysis, an X-ray diffraction analyzer (Ultima IV, manufactured by RIGAKU) is used, CuKα rays (voltage 20 kV, current 10 mA) are used as an X-ray source, the scanning range is 2θ = 10 ° to 70 °, and the scanning speed. Measurement: 10 ° / min, sampling width: 0.01 °, divergence slit: 1 °, divergence vertical restriction slit: 10 mm, scattering slit: 1/6 °, light receiving slit: 0.15 mm, offset angle: 0 ° went.
For reference, the main peak of each crystal phase _{is around 29.157 ° for Y 2} O ₃ , around 27.881 ° for YF ₃ , around 28.064 ° for YOF, and Y ₅ O ₄ F ₇ is detected near 28.114 °.

In the "F-based plasma" column of the "Plasma erosion resistance" column in Table 4, the plasma erosion resistance is evaluated based on the amount of decrease in the thickness of the sprayed coating when a plasma exposure test using F-based plasma is performed. The result was shown.
In the "Cl-based plasma" column of the "Plasma erosion resistance" column in Table 4, the plasma erosion resistance was evaluated based on the amount of decrease in the thickness of the sprayed coating when the plasma exposure test with Cl-based plasma was carried out. The results are shown.

<Plasma exposure test>
The plasma exposure test of the sprayed coating was carried out as follows. That is, first, a 20 mm × 20 mm thermal spray coating is formed on the base material under the above-mentioned thermal spraying conditions, the surface of the thermal spray coating is mirror-polished until the film thickness becomes 2 mm, and then the four corners of the thermal spray coating are covered with masking tape. A test piece was prepared by masking. For the samples in which the thermal spray coating could be formed by both HVOF thermal spraying and APS thermal spraying, the thermal spray coating formed by APS thermal spraying was tested. Then, this test piece was placed on a silicon wafer having a diameter of 300 mm installed on a stage in a chamber of a parallel plate type semiconductor device manufacturing apparatus (ULVAC, NLD-800). Subsequently, under the conditions shown in Table 3 below, F-based plasma or Cl-based plasma was repeatedly generated in a predetermined cycle to perform plasma etching of the central portion of the silicon wafer and the thermal spray coating. As shown in Table 3 below, the F-based plasma was _{generated using a mixed gas of CF 4} and O ₂ (volume ratio: 53.2 / 5) as the etching gas. Further, the Cl-based plasma was _{generated by using a mixed gas of CCl 4} and O ₂ (volume ratio: 53.2 / 5) as the etching gas. The exposure time by each plasma was 0.9 hours including the interval (cooling cycle time). Then, the amount of etching (corrosion amount) of the sprayed coating by each plasma was measured as the amount of decrease in thickness, and the result of sample 1 was shown in Table 4 as a relative value as 1 (index). Specifically, the plasma erosion resistance characteristics are as follows: (Thickness reduction amount per unit time of the sprayed coating of sample 1 [μm / hr]) ÷ (Thickness reduction amount of the sprayed coating of each sample per unit time [ The value calculated by μm / hr]); is shown.
The amount of decrease in the thickness of the sprayed coating was determined by measuring the step between the masked portion and the plasma exposed surface with a surface roughness measuring machine (manufactured by Mitutoyo, SV-3000CNC).

As shown in Table 4, in the case of the spraying slurry conforming to the provisions of the present application, the evaluation of the film forming property was good. Although not shown in Table 4, the thermal spraying slurry conforming to the provisions of the present application uses relatively fine particles having an average particle size of 10 μm or less as the thermal spraying particles. However, the porosity was as high as 10% or less.

On the other hand, the thermal spraying slurry of the sample 26 is considered to be unsuitable as a thermal spraying slurry because the content of the thermal spraying particles is as low as 5% by mass and the thermal spraying efficiency is too low. Further, it is considered that the thermal spraying slurry of the samples 5, 6, 9, and 28 has an excessively high content of thermal spraying particles of 80% by mass or 90% by mass, and it is difficult to prepare the thermal spraying slurry. Further, the thermal spraying slurry of sample 27 has a viscosity of 885 mPa · s, which is too high and has low fluidity, and is considered to be unsuitable as a thermal spraying slurry.

From the comparison of the plasma erosion resistance of the thermal spray coating obtained from the thermal spraying slurry using the thermal spraying particles having the same average particle size, the higher the concentration of the thermal spraying particles contained in the thermal spraying slurry, the more the oxidation of the coating component. It was found that decomposition can be suppressed and high plasma erosion resistance tends to be obtained. However, it has been found that if the concentration of the sprayed particles is too high, the plasma erosion resistance of the obtained film deteriorates due to the problem of fluidity. Therefore, for example, it was found that the solid content concentration of the slurry is more preferably about 30% by mass or more and 60% by mass or less.

Further, from the comparison of the plasma erosion resistance characteristics of the thermal spray coating obtained from the thermal spraying slurry using only water, only ethanol, and a mixed solution of water and ethanol as the dispersion medium, in the case of the thermal spraying slurry composed of the mixed solution. It was found that the sprayed particles tend to be oxidatively decomposed. It was found that the dispersion medium was preferably water alone or ethanol only, rather than a mixed solution of water and ethanol.

From the comparison of the composition of the sprayed particles and the plasma erosion resistance of the sprayed coating obtained from the sprayed slurry having the same content, the larger the average particle size of the sprayed particles, the more the oxidative decomposition of the sprayed coating component is suppressed. It turned out that there is a tendency to do so. It was found that the thermal spraying particles are more preferably about 1 μm or more and 6 μm or less.

Further, from the comparison of the plasma erosion resistance characteristics of the thermal spray coatings obtained from the thermal spraying slurries of the samples 32 to 36, when YOF is used as the thermal spraying particles, a very small amount of YF ₃ is mixed and used to obtain plasma erosion resistance. It was found that the properties tend to be improved.

Further, it was found that when ittrium oxyfluoride was used as the thermal spray amount particles, the plasma erosion resistance property of the thermal spray coating was enhanced as the thermal spraying slurry contained the thermal spray particles having a composition having a high proportion of fluorine.
Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above.

Claims (15)

A thermal spraying slurry containing a thermal spray particle composed of yttrium oxyfluoride containing yttrium (Y), oxygen (O) and fluorine (F) as a constituent element, and a dispersion medium.
The content of the sprayed particles is 10% by mass or more and 70% by mass or less.
The viscosity of the spraying slurry is 300 mPa · s or less.
Here, the sprayed particles are
General formula: _{A slurry for thermal spraying containing yttrium oxyfluoride represented by Y 1} O _1-n F _{1 + 2n} (provided that 0.12 ≦ n ≦ 0.22 is satisfied) in a proportion of 95% by mass or more. The sprayed particles are _{at least one selected from the group consisting of Y 5} O ₄ F ₇ , Y ₆ O ₅ F ₈ , Y ₇ O ₆ F _9, and Y ₁₇ O ₁₄ F ₂₃ at a ratio of 95% by mass or more. The thermal spraying slurry according to claim 1. The spraying slurry according to claim 1 or 2, wherein the sprayed particles contained in the sprayed slurry have a sedimentation rate of 30 μm / sec or more. The spraying slurry according to any one of claims 1 to 3, further containing a dispersant. The slurry for thermal spraying according to any one of claims 1 to 3, further containing a viscosity modifier. The spraying slurry according to any one of claims 1 to 5, further containing a flocculant. The slurry for thermal spraying according to any one of claims 1 to 6, wherein the average particle size of the thermal sprayed particles is 1 nm or more and less than 200 nm. The slurry for thermal spraying according to any one of claims 1 to 7, wherein the average particle size of the thermal sprayed particles is 200 nm or more and 6 μm or less. A method for forming a thermal spray coating, wherein the thermal spraying slurry according to any one of claims 1 to 8 is sprayed to form a thermal spray coating. The method for forming a thermal spray coating according to claim 9 , wherein the thermal spraying slurry containing water as a dispersion medium is sprayed with a high-speed frame to form the thermal spray coating. The method for forming a thermal spray coating according to claim 9 , wherein the thermal spraying slurry containing an organic solvent as the dispersion medium is plasma-sprayed to form the thermal spray coating. The method for forming a thermal spray coating according to any one of claims 9 to 11 , which comprises supplying the thermal spraying slurry to the thermal spraying apparatus by an axial feed method. The spray slurry, with two feeders, the including the variation cycle of the supply amount of the sprayed slurry from the two feeders is fed to the spraying apparatus so as to become opposite in phase to each other, according to claim 9 to The method for forming a thermal spray coating according to any one of 12. The thermal spray slurry feed from the feeder temporarily stored in the tank immediately before the spraying device, comprising providing spraying device spraying slurry in the tank by utilizing free fall, more of claims 9-13 The method for forming a thermal spray coating according to item 1. The method for forming a thermal spray coating according to any one of claims 9 to 14 , which comprises supplying the thermal spraying slurry to the thermal spraying apparatus via a conductive tube.