Ni-based self-fluxing alloy

Abstract

To provide a Ni-based self-fluxing alloy from which a film 6 having excellent compactness, smoothness and corrosion resistance can be obtained.SOLUTION: A metal product 2 has a main part 4 and a film 6. A material of the film 6 is a Ni-based self-fluxing alloy. The Ni-based self-fluxing alloy contains Mo: 5.0 mass% or more and 30.0 mass% or less, B: 0.5 mass% or more and 4.0 mass% or less, Si: 0.5 mass% or more and 10.0 mass% or less, C: 0.01 mass% or more and 0.50 mass% or less, and one or more selected from a group consisting of Fe, Co, and Cu: 0.1 mass% or more and 10.0 mass% or less in total. The balance is Ni and unavoidable impurities.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This specification discloses an alloy having self - solubility. Specifically, this specification discloses a self - fluxing alloy whose base metal is Ni.

Background Art

[0002] Various Ni - based self - fluxing alloys are defined in "JIS H8303 2010". This Ni - based self - fluxing alloy is used in thermal spraying, build - up welding, centrifugal casting, etc. to obtain a coating. The main part of the metal product is covered by this coating. The coating may be subjected to a remelting treatment. In the remelting treatment, the coating is heated and a liquid phase appears in the coating. This liquid phase solidifies upon cooling. The remelting treatment can enhance the denseness of the coating. Since the solidus temperature or liquidus temperature is low, the Ni - based self - fluxing alloy is suitable for the remelting treatment. An example of the Ni - based self - fluxing alloy is disclosed in Japanese Patent Laid - Open No. 8 - 134569. Another example of the Ni - based self - fluxing alloy is disclosed in Japanese Patent Laid - Open No. 2001 - 342530.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Conventional Ni - based self - fluxing alloys contain B and Si. B and Si are easily oxidized. Due to the oxidation of B and Si in the remelting treatment, the metal oxides in the coating are reduced. This reduction reduces the amount of metal oxides in the coating. Furthermore, due to the oxidation of B and Si, borosilicate glass is formed in the coating. This borosilicate glass forms the surface of the coating and blocks pores. B and Si contribute to the densification, smoothing, and homogenization of the coating.

[0005] Conventional nickel-based self-fluxing alloys also contain chromium (Cr). Cr combines with carbon (C) to form carbides (Cr7C3). Cr further combines with boron (B) to form borides (CrB). These carbides and borides are hard. These carbides and borides can contribute to the hardness and wear resistance of the coating. Cr also contributes to the corrosion resistance of the coating.

[0006] Cr combines with O to form an oxide (Cr2O3). This oxide is stable and therefore difficult to reduce even by remelting. This oxide remains in the coating after remelting. This oxide impairs the density and smoothness of the coating. The adverse effects of Cr oxide are particularly significant in coatings obtained by thermal spraying where the distance between the sprayer and the object to be coated is long. This is because in thermal spraying with long distances, the flight time of the molten metal is longer, and therefore the oxidation of Cr progresses more rapidly during flight.

[0007] Conventional coatings have room for improvement. The applicant's intention is to provide a Ni-based self-fluxing alloy that can produce coatings with excellent density, smoothness, and corrosion resistance. [Means for solving the problem]

[0008] The Ni-based autoflux alloy according to this embodiment is Mo: 5.0% by mass or more and 30.0% by mass or less, B: 0.5% by mass or more and 4.0% by mass or less, Si: 0.5% by mass or more and 10.0% by mass or less, C: 0.01% by mass or more and 0.50% by mass or less and One or more elements selected from the group consisting of Fe, Co, and Cu: total amount of 0.1% to 10.0% by mass. It contains [component name]. The remainder consists of Ni and unavoidable impurities.

[0009] This specification is also directed to powders. The material of this powder is a Ni-based autoflux alloy. This Ni-based autoflux alloy is Mo: 5.0% by mass or more and 30.0% by mass or less, B: 0.5% by mass or more and 4.0% by mass or less, Si: 0.5% by mass or more and 10.0% by mass or less, C: 0.01% by mass or more and 0.50% by mass or less and One or more elements selected from the group consisting of Fe, Co, and Cu: total amount of 0.1% to 10.0% by mass. It contains [component name]. The remainder consists of Ni and unavoidable impurities.

[0010] This specification also applies to a product. This product has a coating. The material of this coating is a Ni-based auto-flux alloy. This Ni-based auto-flux alloy is Mo: 5.0% by mass or more and 30.0% by mass or less, B: 0.5% by mass or more and 4.0% by mass or less, Si: 0.5% by mass or more and 10.0% by mass or less, C: 0.01% by mass or more and 0.50% by mass or less and One or more elements selected from the group consisting of Fe, Co, and Cu: total amount of 0.1% to 10.0% by mass. It contains [component name]. The remainder consists of Ni and unavoidable impurities. [Effects of the Invention]

[0011] A dense and smooth-surfaced coating can be obtained from this Ni-based self-fluxing alloy. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic cross-sectional view showing a part of a metal product according to one embodiment. [Figure 2] Figure 2 is a conceptual diagram showing an example of a manufacturing method for the metal product shown in Figure 1. [Modes for carrying out the invention]

[0013] Preferred embodiments will be described below, with reference to drawings as appropriate.

[0014] The metal product 2 shown in FIG. 1 has a main part 4 and a coating 6. The coating 6 covers the surface of the main part 4. The coating 6 may cover the entire surface of the main part 4 or may cover a part thereof. A typical material of the main part 4 is a metal material. Various metal materials are suitable for the main part 4. The coating 6 can be obtained by a spraying method to be described in detail later. The coating 6 may be obtained by a build-up welding method, a centrifugal casting method, or the like. In these methods, powder is used. The coating 6 may be obtained through a remelting process to be described in detail later.

[0015] This powder is an aggregate of a large number of particles. The material of these particles is a Ni-based self-fluxing alloy. This Ni-based self-fluxing alloy Mo: 5.0 mass% or more and 30.0 mass% or less, B: 0.5 mass% or more and 4.0 mass% or less, Si: 0.5 mass% or more and 10.0 mass% or less, C: 0.01 mass% or more and 0.50 mass% or less and one or more selected from the group consisting of Fe, Co, and Cu: in total 0.1 mass% or more and 10.0 mass% or less is contained. The balance is Ni and inevitable impurities.

[0016] As described above, in the conventional Ni-based self-fluxing alloy, Cr contributes to the corrosion resistance. The Ni-based self-fluxing alloy according to this embodiment substantially does not contain Cr. On the other hand, this Ni-based self-fluxing alloy contains Fe, Co, or Cu. Fe, Co, and Cu can be respectively dissolved in the Ni matrix. According to the findings obtained by the present inventor, Fe, Co, or Cu dissolved in the matrix contributes to the corrosion resistance of the coating 6. The coating 6 containing Mo and containing Fe, Co, or Cu is excellent in corrosion resistance despite not containing Cr. In other words, Fe, Co, and Cu can replace Cr from the viewpoint of corrosion resistance. This Ni-based self-fluxing alloy is particularly excellent in corrosion resistance to acids. Even when the metal product 2 is placed in a hydrochloric acid environment or a sulfuric acid environment, the coating 6 is hardly corroded. <![CDATA[ ]]><![CDATA[

[0017] ]]><![CDATA[ ]]>In other words, the applicants have for the first time discovered that in Ni-based self-fluxing alloys, where corrosion resistance is a concern due to the absence of Cr, Fe, Co, and Cu complement the corrosion resistance of Cr without interfering with the formation of borides and other phases. This is evident from the fact that, as will be described later, Ni-based self-fluxing alloys that do not contain any of Fe, Co, or Cu exhibit insufficient corrosion resistance to hydrochloric acid and sulfuric acid.

[0018] The standard Gibbs free energies of formation at 1000°C for oxides of Cr, Mo, Fe, Co, and Cu are as follows: Cr2O3: -538kJ / molO2 MoO3: -284kJ / molO2 Fe3O4: -364kJ / molO2 CoO: -289kJ / molO2 Cu2O: -152kJ / molO2 As is evident from these standard Gibbs free energies of formation, oxides of Mo, Fe, Co, and Cu are thermally less stable than Cr oxides. Oxides of Mo, Fe, Co, and Cu are readily sublimated and reduced during the remelting process of the film 6. In a film 6 that is substantially free of Cr and contains Mo, Fe, Co, or Cu, the amount of metal oxide remaining after the remelting process is small. This film 6 is dense.

[0019] In other words, the applicants have for the first time discovered that in this Ni-based self-fluxing alloy, the solid solution of Fe, Co, or Cu in the Ni matrix enhances the corrosion resistance of the material and the coating, and also provides a deoxidation and sublimation effect.

[0020] The reduction of oxides of Mo, Fe, Co, and Cu causes B and Si to bond with O. The oxides obtained by this bonding (B2O3 and SiO2) form borosilicate glass within the film 6. This borosilicate glass rises to the surface of the film 6. This borosilicate glass seals the pores and suppresses the roughness of the film. A film 6 that is substantially free of Cr and contains Mo, Fe, Co, or Cu has excellent smoothness. If the metal product 2 is a mold, the surface of the molded product obtained from this mold is also smooth. In this molded product, the inhibition of mechanical properties caused by surface roughness can be suppressed.

[0021] The composition of this Ni-based autoflux alloy is described in detail below.

[0022] [Molybdenum (Mo)] Mo combines with C to form a complex carbide. Mo further combines with B to form a complex boride. Complex carbides and complex borides can contribute to the hardness and wear resistance of the coating 6. During thermal spraying, Mo combines with O to form an oxide (MoO3). This oxide is sublimated and reduced during the remelting process. Therefore, the amount of residual Mo oxide in the coating 6 after the remelting process is small. In this coating 6, inhibition of density and smoothness due to Mo oxides is less likely to occur. From the viewpoint of hardness and wear resistance of the coating 6, the Mo content is preferably 5.0% by mass or more, more preferably 8.3% by mass or more, and particularly preferably 10.8% by mass or more. If the Mo content is excessive, excess Mo complex borides are generated. Excess Mo complex borides inhibit the toughness of the coating 6. Furthermore, if the powder is manufactured by atomization, excess Mo can lead to nozzle clogging due to coarse borides. From the viewpoint of toughness and ease of handling, the Mo content is preferably 30.0% by mass or less, more preferably 28.5% by mass or less, and particularly preferably 25.3% by mass or less.

[0023] [Boron (B)] In alloys containing B, low solidus and liquidus temperatures can be achieved. B can contribute to self-fluxability in remelting treatment. B can reduce metal oxides in remelting treatment. This reduction results in a low amount of residual metal oxide, and therefore a film 6 with excellent density can be obtained. B combines with Mo to form diborides. These diborides contribute to the hardness and wear resistance of the film 6. Furthermore, B exists in the matrix as Ni3B, a pseudo-ternary eutectic structure, and contributes to the hardness and wear resistance of the film 6. From these viewpoints, the B content is preferably 0.5% by mass or more, more preferably 0.6% by mass or more, and particularly preferably 1.0% by mass or more. If the B content is excessive, excess diborides are generated. Excess diborides inhibit the toughness of the film 6. Furthermore, if the powder is manufactured by atomization, excess B can lead to nozzle clogging due to coarse borides. From these perspectives, the content of B is preferably 4.0% by mass or less, more preferably 3.9% by mass or less, and particularly preferably 3.6% by mass or less.

[0024] [Silicon (Si)] In alloys containing Si, low solidus and liquidus temperatures can be achieved. Si can contribute to self-fluxability in the remelting process. Si can reduce metal oxides in the remelting process. This reduction results in a low amount of residual metal oxide, and therefore a film 6 with excellent density can be obtained. Furthermore, Si exists in the matrix as Ni3Si, a pseudo-ternary eutectic structure, and contributes to the hardness and wear resistance of the film 6. From these viewpoints, the Si content is preferably 0.5 mass% or more, more preferably 1.1 mass% or more, and particularly preferably 2.9 mass% or more. Excess Si inhibits the toughness of the film 6. From this viewpoint, the Si content is preferably 10.0 mass% or less, more preferably 9.3 mass% or less, and particularly preferably 8.2 mass% or less.

[0025] [Carbon (C)] C contributes to the high hardness of the coating 6. C dissolves in Ni, strengthening the substrate and increasing its hardness. Furthermore, when the powder is manufactured by atomization, C suppresses pores in the powder. This is presumed to be because C contributes to the deoxidation of the molten metal before atomization, reducing the gaseous component of the molten metal. From molten metal with a low gaseous component, a powder with fewer pores, which are generated when these gaseous components gasify during the solidification process, can be obtained. From powder with fewer pores, a dense coating 6 can be obtained. From these viewpoints, the C content is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and particularly preferably 0.04% by mass or more. Excess C inhibits the toughness of the coating 6. From this viewpoint, the C content is preferably 0.50% by mass or less, more preferably 0.48% by mass or less, and particularly preferably 0.32% by mass or less.

[0026] High-purity raw materials have a low carbon content, but their cost is high. On the other hand, low-purity raw materials have a low cost, but their carbon content is high. High-purity raw materials may be melted, and carbon may be actively added to them. Low-purity raw materials may be used, and carbon derived from these raw materials may remain in the Ni-based self-fluxing alloy. The Ni-based self-fluxing alloy may contain both actively added carbon and carbon derived from the raw materials. The Ni-based self-fluxing alloy may contain only either actively added carbon or carbon derived from the raw materials. In any case, if the total carbon content is within the above range, a high-quality coating 6 can be obtained.

[0027] [Iron (Fe)] Fe can be dissolved in the Ni matrix. According to the inventors' findings, Fe dissolved in the matrix contributes to the corrosion resistance of the coating 6. The coating 6, which contains both Mo and Fe, exhibits excellent corrosion resistance despite not containing Cr. In other words, Fe can substitute for Cr in terms of corrosion resistance. Fe dissolved in the Ni matrix can also contribute to the strength of the coating 6. Fe can form oxides, but these oxides can be reduced and sublimated during the remelting process. The amount of oxide remaining in the coating 6 after the remelting process is small. This coating 6 is dense. Furthermore, this coating 6 is less prone to damage caused by cracks originating from Fe precipitates. From these viewpoints, the Fe content is preferably 0.1% by mass or more, more preferably 1.7% by mass or more, and particularly preferably 2.1% by mass or more. From the viewpoint of the toughness of the coating 6, the Fe content is preferably 10.0% by mass or less.

[0028] [Cobalt (Co)] Co can be dissolved in the Ni matrix. According to the inventors' findings, Co dissolved in the matrix contributes to the corrosion resistance of the coating 6. A coating 6 containing Mo and Co exhibits excellent corrosion resistance despite not containing Cr. In other words, Co can substitute for Cr in terms of corrosion resistance. Co dissolved in the Ni matrix can also contribute to the strength of the coating 6. Although Co can form oxides, these oxides can be reduced and sublimated during the remelting process. The amount of oxide remaining in the coating 6 after the remelting process is small. This coating 6 is dense. Furthermore, this coating 6 is less prone to damage caused by cracks originating from Co precipitates. From these viewpoints, the Co content is preferably 0.1% by mass or more, more preferably 1.3% by mass or more, and particularly preferably 1.9% by mass or more. From the viewpoint of the toughness of the coating 6, the Co content is preferably 10.0% by mass or less.

[0029] [Copper (Cu)] Cu can be dissolved in the Ni matrix. According to the inventors' findings, Cu dissolved in the matrix contributes to the corrosion resistance of the coating 6. A coating 6 containing both Mo and Cu exhibits excellent corrosion resistance despite not containing Cr. In other words, Cu can substitute for Cr in terms of corrosion resistance. Cu dissolved in the Ni matrix can also contribute to the strength of the coating 6. Cu can stabilize the composition by promoting the formation of carbides and borides. Although Cu can form oxides, these oxides can be reduced and sublimated during the remelting process. The amount of oxide remaining in the coating 6 after the remelting process is small. This coating 6 is dense. Furthermore, this coating 6 is less prone to damage caused by cracks originating from Cu precipitates. From these viewpoints, the Cu content is preferably 0.1% by mass or more, more preferably 1.9% by mass or more, and particularly preferably 2.5% by mass or more. From the viewpoint of the toughness of the coating 6, the Cu content is preferably 10.0% by mass or less.

[0030] [Fe, Co, and Cu] As mentioned above, Fe, Co, and Cu can each contribute to the corrosion resistance and density of the coating 6. Suitable embodiments of Ni-based self-fluxing alloys for the coating 6 are listed below. (a) an embodiment containing Fe and substantially free of Co and Cu (b) an embodiment containing Co and substantially free of Fe and Cu. (c) A form containing Cu and substantially free of Fe and Co (d) A form containing Fe and Co, but substantially free of Cu. (e) A form containing Fe and Cu, but substantially free of Co. (f) A form containing Co and Cu, and substantially free of Fe. (g) Embodiments containing Fe, Co, and Cu The total content (TC) of Fe, Co, and Cu is preferably 0.1% by mass or more, more preferably 1.9% by mass or more, and particularly preferably 2.5% by mass or more. From the viewpoint of the toughness of the coating 6, this total content TC is preferably 10.0% by mass or less.

[0031] [Nickel (Ni)] The base material of this alloy is Ni. Ni can contribute to the low melting point of the alloy. Ni can further contribute to the corrosion resistance and toughness of the coating 6. From these viewpoints, the Ni content is preferably 50% by mass or more, and particularly preferably 55% by mass or more.

[0032] [impurities] This Ni-based autoflux alloy contains unavoidable impurities. One example of an unavoidable impurity is Cr. The Cr content in this Ni-based autoflux alloy is extremely small. Therefore, even if this alloy is subjected to thermal spraying or the like, almost no Cr oxides are formed. A coating 6 with excellent density can be obtained from this alloy. From the viewpoint of density, the Cr content in this alloy is preferably 0.010 mass% or less, and particularly preferably 0.005 mass% or less.

[0033] [Solidus temperature] From the viewpoint of facilitating the formation of the coating 6, the solidus temperature of the Ni-based autoflux alloy is preferably 1000°C or lower, more preferably 985°C or lower, and particularly preferably 975°C or lower.

[0034] [Liquidus temperature] From the viewpoint of facilitating the formation of the coating 6, the liquidus temperature of the Ni-based auto-flux alloy is preferably 1250°C or lower, more preferably 1200°C or lower, and particularly preferably 1190°C or lower.

[0035] [Powder manufacturing] The powder is preferably obtained by atomization. Gas atomization, disc atomization, water atomization, centrifugal atomization, etc., are employed. Gas atomization and disc atomization are preferred atomization methods. The powder obtained by atomization may be subjected to mechanical milling or the like.

[0036] [Formation of a coating] Typically, the coating 6 is formed by thermal spraying. An example of thermal spraying is shown in Figure 2. In this method, powder made of a Ni-based self-fluxing alloy is heated in a thermal sprayer 8. This heating causes the powder particles to become molten or semi-molten. These particles 10 are sprayed onto the main part 4 (i.e., the object to be coated) as shown in Figure 2. The particles 10 fly and collide with the main part 4. After the collision, the particles 10 solidify, forming a solidified layer. Since the spraying of particles 10 is continuous, particles 10 also collide with and solidify in the solidified layer, causing the solidified layer to grow. In this way, the coating 6 is formed. During flight, the particles 10 are exposed to the atmosphere between the thermal sprayer 8 and the main part 4. This causes some of the metallic elements in the Ni-based self-fluxing alloy to oxidize, forming metal oxides in the coating 6. The coating 6 may also be formed by methods other than thermal spraying. Examples of methods other than thermal spraying include overlay welding and centrifugal casting. Since the solidus temperature of the Ni-based autoflux alloy is low, damage to the main part 4 can be suppressed in either method.

[0037] [Remelting process] The film 6 may be subjected to a remelting treatment. In the remelting treatment, the film 6 is heated until it reaches a temperature above the solidus temperature. This heating generates a liquid phase in the film 6. The film 6 becomes a solid-liquid mixture. This liquid phase solidifies, and the film 6 is reformed. The remelting treatment increases the density of the film 6. During the remelting treatment, some of the metal oxide is reduced and disappears. The preferred temperature to reach in the remelting treatment is in the range of 1000°C to 1200°C.

[0038] [Thermal spray distance] In Figure 2, the symbol L1 represents the thermal spray distance. The thermal spray distance L1 is the distance between the tip 12 of the thermal sprayer 8 and the main part 4. In thermal spraying with a large thermal spray distance L1, the molten particles 10 are exposed to the atmosphere for a longer time. Thermal spraying with a large thermal spray distance L1 can form a coating 6 with a high concentration of metal oxides. The Ni-based self-fluxing alloy according to this embodiment contains substantially no Cr and contains Fe, Co, or Cu. Therefore, a large amount of metal oxide is reduced and eliminated by the remelting process. Even with thermal spraying with a large thermal spray distance L1, a high-quality coating 6 can be obtained by using the Ni-based self-fluxing alloy powder according to this embodiment. Thermal spraying with a large thermal spray distance L1 also offers superior safety. While the normal thermal spray distance is generally 300 mm or less, the Ni-based self-fluxing alloy according to this embodiment can form a good coating 6 even when the thermal spray distance L1 is 350 mm or more, even 400 mm or more, and even around 500 mm.

[0039] [Manufacturing method] This specification is also directed to a method for manufacturing a metal product 2. This manufacturing method is (1) The material is a Ni-based autoflux alloy, and this Ni-based autoflux alloy is Mo: 5.0% by mass or more and 30.0% by mass or less, B: 0.5% by mass or more and 4.0% by mass or less, Si: 0.5% by mass or more and 10.0% by mass or less, C: 0.01% by mass or more and 0.50% by mass or less and One or more elements selected from the group consisting of Fe, Co, and Cu: total amount of 0.1% to 10.0% by mass. The process of preparing a powder containing, with the remainder being Ni and unavoidable impurities, (2) Heat the powder to 600°C or more and 800°C or less in a thermal spraying machine 8, and spray the powder particles 10 onto the main part 4 to obtain a coating 6 laminated on the main part 4. and (3) A step of subjecting the above coating 6 to a remelting treatment. Includes. [Examples]

[0040] The effects of the Ni-based autoflux alloys described in the following examples will be clarified, but the scope disclosed herein should not be interpreted as limiting based on the description of these examples.

[0041] [Example 1] Raw materials having the composition shown in Table 1 were placed in a refractory crucible. These raw materials were induced melted in argon gas to obtain molten metal. This molten metal was discharged from the crucible nozzle and sprayed with high-pressure nitrogen gas to obtain powder. This powder was classified by sieving to adjust the particle size to between 45 μm and 125 μm. Meanwhile, a columnar main part made of SUS304 with a size of φ50 mm was prepared. The powder was subjected to gas flame spraying to form a 1 mm thick coating on the surface of the main part. The main part and the coating were placed in an electric furnace and held at a temperature of 940 °C for 30 minutes. The coating was air-cooled to obtain the metal product of Example 1.

[0042] [Examples 2-19 and Comparative Examples 1-7 and 10-12] Except for the composition being as shown in Tables 1 and 2 below, the metal products of Example 2-19 and Comparative Examples 1-7 and 10-12 were obtained in the same manner as in Example 1.

[0043] [Comparative Examples 8 and 9] Atomization was attempted in the same manner as in Example 1, except that the composition was as shown in Table 2 below. Atomization was stopped because the molten metal clogged the nozzle.

[0044] [Solidus temperature and liquidus temperature] The solidus and liquidus temperatures of the powder were measured using a thermal analyzer (DTA) under the following conditions. Powder quantity: 20mg Atmosphere: After vacuuming, argon gas is flowed in at 200 ml / min. Heating rate: 20°C / min Starting temperature: room temperature Achieved temperature: 1500℃ (held for 5 minutes) Cooling rate: -20℃ / min Among the exothermic peaks observed in the DTA signal during cooling, the temperature at which exothermic generation begins at the highest temperature is the liquidus temperature, and the temperature at which exothermic generation ends at the lowest temperature is the solidus temperature. These results are shown in Tables 1 and 2 below.

[0045] [Transverse bending strength] A copper substrate was placed inside an arc melting apparatus. Powder was then placed on top of this copper substrate. After evacuating the inside of the arc melting apparatus, the powder was arc-melted in an argon gas atmosphere to obtain an ingot. During the arc melting process, the ingot was rotated more than 10 times to suppress the uneven distribution of its composition. The ingot was then subjected to heat treatment under the following conditions. Atmosphere: Argon gas Temperature: 950℃ Retention time: 24 hours retention Cooling: Furnace cooling Test specimens were obtained from this ingot and subjected to a bending test in accordance with the provisions of JIS Z 2248 to obtain the bending strength (three-point bending strength). The results are shown in Tables 1 and 2 below.

[0046] [Corrosion resistance] A test specimen measuring 10 × 14 × 4 mm was obtained from an ingot obtained using the same method as in the bending test. This test specimen was subjected to corrosion resistance tests under the following conditions 1 and 2. Condition 1 Corrosive solution: 10% hydrochloric acid aqueous solution Temperature: 40℃ Time: 10 hours Condition 2 Corrosive solution: 10% sulfuric acid aqueous solution Temperature: 40℃ Time: 10 hours The resulting corrosion levels are shown in Tables 1 and 2 below.

[0047] [Hardness] Test specimens were cut from the coating after the remelting treatment, and the cross-sections were polished. The Vickers hardness of these cross-sections was measured under a load of 2.94 N. The average values ​​of 10 measurements are shown in Tables 1 and 2 below.

[0048] [Density rate] A test specimen was cut from the coating after the remelting treatment, and the cross-section was polished. Microscopic images (magnification: 25x) of this cross-section were obtained using an optical microscope. Images of 0.5 × 0.5 mm zones were binarized using the public domain image processing software "Image J 1.45" to separate the powder-filled portion from the void portion. The density (100 × (AB) / A) was calculated from the image area (A) and the void area (B). The average density values ​​obtained from the six images are shown in Tables 1 and 2 below.

[0049] [Table 1]

[0050] [Table 2]

[0051] Each of the alloys shown in Tables 1 and 2 contains unavoidable impurities.

[0052] As shown in Tables 1 and 2, the alloys in each example exhibit excellent performance in various aspects. These evaluation results clearly demonstrate the superiority of this Ni-based self-fluxing alloy. [Industrial applicability]

[0053] The alloy described above is suitable for machine parts and the like. This alloy is particularly suitable for coatings on boiler tubes, heating barrels, sleeves, molds, and the like. [Explanation of symbols]

[0054] 2.. Products 4. Main body 6. Coating 8. Thermal spraying machine 10...particles 12...tip

Claims

1. Mo: 5.0% by mass or more and 30.0% by mass or less, B: 0.5% by mass or more and 4.0% by mass or less, Si: 0.5% by mass or more and 10.0% by mass or less, C: 0.01% by mass or more and 0.50% by mass or less and One or more elements selected from the group consisting of Fe, Co, and Cu: total amount of 0.1% by mass or more and 10.0% by mass or less It contains, A Ni-based autoflux alloy in which the remainder consists of Ni and unavoidable impurities.

2. The material is a Ni-based self-fluxing alloy. The above Ni-based autoflux alloy, Mo: 5.0% by mass or more and 30.0% by mass or less, B: 0.5% by mass or more and 4.0% by mass or less, Si: 0.5% by mass or more and 10.0% by mass or less, C: 0.01% by mass or more and 0.50% by mass or less and One or more elements selected from the group consisting of Fe, Co, and Cu: total amount of 0.1% by mass or more and 10.0% by mass or less It contains, A powder in which the remainder consists of Ni and unavoidable impurities.

3. It has a coating, The material of the above coating is a Ni-based self-fluxing alloy. The above Ni-based autoflux alloy, Mo: 5.0% by mass or more and 30.0% by mass or less, B: 0.5% by mass or more and 4.0% by mass or less, Si: 0.5% by mass or more and 10.0% by mass or less, C: 0.01% by mass or more and 0.50% by mass or less and One or more elements selected from the group consisting of Fe, Co, and Cu: total amount of 0.1% by mass or more and 10.0% by mass or less It contains, A product in which the remainder consists of Ni and unavoidable impurities.

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