Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F9/00—Making metallic powder or suspensions thereof
  • B22F9/02—Making metallic powder or suspensions thereof using physical processes
  • B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
  • B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
  • C22C19/03—Alloys based on nickel or cobalt based on nickel
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
  • C22C19/03—Alloys based on nickel or cobalt based on nickel
  • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C30/00—Alloys containing less than 50% by weight of each constituent
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
  • C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
  • C23C4/06—Metallic material
  • C23C4/08—Metallic material containing only metal elements

Definitions

• self-fluxing alloys include Ni-based alloys and Co-based alloys, as specified in Japanese Industrial Standard (JIS) H8303 (Self-fluxing alloy thermal spraying). These self-fluxing alloys are primarily used in surface treatments such as thermal spraying and build-up welding, and are used to form coatings with excellent corrosion and wear resistance. The hardness of these coatings is around 15 to 60 HRC.
• the composition specified in JIS H8303 includes essential components of approximately 1.0 to 4.5 mass% B and 1.5 to 5.0 mass% Si.
• the fusing temperature is usually around 1000 to 1200°C.
• some of the easily oxidized B and Si in the alloy become B 2 O 3 and SiO 2 , dissolving the metal oxides in the thermal spray coating and on the substrate surface, forming a type of borosilicate glass that floats to the surface of the thermal spray coating like slag.
• This flux action results in a thermal spray coating with very few oxides and pores.
• spray particles fuse together within the thermal spray coating, resulting in a uniform structure.
• interdiffusion occurs between the substrate and the thermal spray coating during fusing, forming an alloy layer about several tens of microns thick at the boundary, which is metallurgically bonded.
• self-fluxing alloys exhibit excellent wear resistance because they contain primary and eutectic oxides and carbides within their structure. They also exhibit excellent corrosion resistance in various corrosive environments, such as hydrochloric acid, sulfuric acid, hydrofluoric acid, and caustic soda.
• Self-fluxing alloys are primarily used in surface treatments such as thermal spraying and build-up welding, forming coatings with excellent corrosion and wear resistance. Their hardness is approximately 15 to 60 HRC. The characteristics of self-fluxing alloys in terms of coating density are described below. Specified in JIS H 8303 (Self-fluxing alloy thermal spraying), they are nickel-based and cobalt-based alloys containing flux components such as B and Si. A dense coating can be obtained by performing a fusing process after thermal spraying. The JIS-specified compositions include approximately 1.0 to 4.5 mass% B and 1.5 to 5.0 mass% Si as essential components.
• this fusing process is performed at around 1000 to 1200°C.
• some of the easily oxidized B and Si in the alloy become B2O3 and SiO2 , dissolving the metal oxides in the thermal spray coating and on the substrate surface, forming a type of borosilicate glass that floats to the surface of the thermal spray coating like slag.
• This flux action makes it easy to obtain a thermal spray coating with few oxides and pores.
• spray particles fuse together within the thermal spray coating, facilitating a homogenous structure.
• interdiffusion occurs between the substrate and the thermal spray coating during fusing, forming an alloy layer approximately several tens of microns thick at the boundary, facilitating metallurgical bonding.
• Self-fluxing alloys contain primary and eutectic oxides and carbides in their structure, so they are generally expected to have excellent wear resistance. They are also expected to have corrosion resistance in various corrosive environments such as hydrochloric acid, sulfuric acid, hydrofluoric acid, and caustic soda.
• the composition of the alloy contains P: 0.2-6.0%, B: 0.1-4.5%, Si: 0.1-5.0%, C: 0.00-2.00%, Cr: 0.0-30.0%, Mo: 0.0-9.0%, W: 0.0-18.0%, Cu: 0.0-10.0%, Mn: 0.0-10.0%, Fe: 0.0-10.0%, Co: 0.0-10.0%, Al: 0.00
• a Ni-based self-fluxing alloy consisting of P: 0.00-0.20%, Ti: 0.00-0.20%, Zr: 0.00-0.20%, and Hf: 0.00-0.20%, and satisfying 2.3 ⁇ P%+B%+Si% ⁇ 11.0, Mo%+W%/2 ⁇ 9.0, and Al%+Ti%+Zr%+Hf% ⁇ 0.20 (see Patent Document 1 (JP 2023-31420 A)).
• a high-melting-point base material typically an Fe-based material such as stainless steel SUS304 (melting point 1398-1427°C) or general structural steel (melting point approximately 1580°C)
• a Ni-based self-fluxing alloy to improve corrosion resistance and wear resistance.
• the temperature during application such as thermal spraying, or the subsequent remelting process, has had little effect on the melting or deformation of the base material.
• the higher the temperature during coating application or remelting treatment the more easily the contained B diffuses, reacting with Fe and Cr in the substrate and causing the crystallization of hard, coarse borides, which may impair the adhesion between the substrate and the coating.
• the crystal grains in the stainless steel substrate become coarse, causing a decrease in strength, and can cause excessive deterioration in corrosion resistance at the interface with the Ni-based self-fluxing alloy coating.
• B and Si crystallize as hard borides and silicides, which play an effective role in improving hardness and wear resistance.
• attempts have been made to address this by lowering the Cr content to suppress the crystallization of these hard phases, such as SFNi1 (15-30 HRC), SFNi2 (30-40 HRC), and SFNi3 (40-50 HRC).
• SFNi1 15-30 HRC
• SFNi2 (30-40 HRC
• SFNi3 40-50 HRC
• the Ni-based self-fluxing alloy in Patent Document 1 contains P, so its solidus or liquidus temperature is low, allowing a coating to be formed by processing at a relatively low temperature, and the main part is less likely to be exposed to high temperatures.
• the remelting heat treatment temperature remains high as before, coarse P compounds tend to form, a fine structure is not obtained, and the substrate is prone to deformation when forming the coating, so it is still not satisfactory.
• the present invention therefore aims to provide a high-melting Ni-based alloy and atomized powder that (1) contains P, resulting in a lower solidus temperature than conventional self-fluxing alloys (JIS H 8303), allowing for easy film formation at low temperatures and subsequent heat treatment to form a dense film at low temperatures, and (2) has a structure in which P is dissolved in a ⁇ Ni matrix and/or compounds containing P are finely dispersed.
• Another object of the present invention is to provide a film using this that has excellent corrosion resistance, crack resistance, and toughness, and to provide parts equipped with such a film.
• Ni-Si-B ternary eutectic temperature
• the eutectic temperature of Ni-P is 870°C, and they thought that adding P would result in a solidus temperature that was dramatically lower than that of conventional materials (Ni-Si-B system).
• the ability to perform low-temperature processing means that when applying a coating, for example when spraying atomized powder of the material of the present invention to form a coating, it is possible to spray at a lower temperature than before, successfully reducing the temperature not only for the remelting process but also during spraying. Furthermore, whereas there was previously a limit to the spraying distance, it is now possible to spray over longer distances, which also leads to improved handling during spraying.
• P dissolves in the ⁇ Ni matrix and/or compounds containing P disperse in precipitated phases with a size of 10 ⁇ m or less, forming a mesh-like network structure, improving the strength of the matrix. Furthermore, because compounds with a precipitated phase size of 10 ⁇ m or less are finely dispersed in the Ni-Ni 3 P eutectic, it is possible to maintain uniform strength in the matrix, and uniform hardness is obtained as a coating. This has succeeded in achieving not only wear resistance, but also both hardness and toughness, which was previously difficult to achieve.
• the hard phase is a boride or a carbide;
• the hard phase has an equivalent circle diameter of 20 ⁇ m or less, 2.
• a high melting property Ni-based alloy coating comprising the high melting property Ni-based alloy according to any one of aspects 1 to 3.
• the high melting property Ni-based alloy coating is a remelted coating that has been subjected to a remelting treatment at a temperature of less than 940°C, the porosity P A of the remelted coating and the porosity P B of the thermal spray coating before the remelting treatment satisfy the relationship P A /P B ⁇ 0.5; 5.
• Atomized powder for film formation comprising the high melting point Ni-based alloy according to any one of aspects 1 to 3.
• the addition of P in the present invention enables processing at lower temperatures than conventional methods, thereby solving the following problems: (i) melting and deformation of the substrate during remelting processing; (ii) reduced adhesion between the substrate and the coating due to hard, coarse borides formed by the diffusion of B; (iii) reduced strength and corrosion resistance due to coarsening of the substrate's crystal grains; and (iv) increased CO2 emissions due to increased fuel consumption.
• the ability to perform low-temperature processing means that when applying a coating, for example, by thermal spraying the atomized powder of the material of the present invention, it can be sprayed at a lower temperature than conventional methods, thereby achieving the benefits of not only the remelting processing but also the low-temperature thermal spraying process.
• conventional methods were limited in the spraying distance, it is now possible to spray over longer distances, leading to improved handling during thermal spraying.
• P dissolves in the ⁇ Ni matrix and/or compounds containing P as precipitates with a size of 10 ⁇ m or less, and these compounds form a mesh-like network structure, which improves the strength of the matrix. Furthermore, because compounds with a precipitated phase size of 10 ⁇ m or less are finely dispersed in the Ni-Ni 3 P eutectic, it is possible to maintain uniform strength in the matrix and obtain uniform hardness as a coating. This makes it possible to achieve not only wear resistance but also both hardness and toughness, which was previously difficult to achieve.
• FIG. 1 is an optical microscope image showing a cross-sectional microscopic image of an as-sprayed coating formed by thermal spraying a Ni-based alloy having the composition of the present invention onto a substrate.
• FIG. 2 is an optical microscope image of an example of the present invention showing a cross-sectional micrograph of the coating shown in FIG. 1 after remelting treatment at less than 940°C.
• FIG. 3 is an optical microscope image of a comparative example showing a cross-sectional micrograph of the coating shown in FIG. 1 after remelting treatment at 940° C. or higher.
• P 0.1-7.0%
• P is an essential element for lowering the solidus temperature. However, if added in excessive amounts, coarse phosphides crystallize, resulting in excessively high hardness, embrittling the coating, and making machining difficult. Addition of less than 0.1% does not sufficiently lower the solidus temperature, while addition of more than 7.0% excessively raises the liquidus temperature.
• the P content is preferably greater than 0.2% and less than 6.0%, and more preferably greater than 0.5% and less than 5.0%.
• the effect of P allows for an unprecedentedly low solidus temperature that could not be achieved by adding B or Si alone, making remelting possible at temperatures below 1000°C, even below 950°C, and even as low as the 800°C range.
• the solidus temperature is so low, thermal spraying is possible at lower temperatures than before. Therefore, not only can it be applied by remelting, but it can also be applied by reducing the thermal energy used during coating application by 10 to 20 percent.
• P improves the strength of the matrix by dispersing P-containing and/or P-solidified compounds with precipitate phases of 10 ⁇ m or less in size in the ⁇ -Ni matrix, forming a network-like structure.
• the dark gray areas in Figures 2 and 3 correspond to the dispersed P-containing and/or P-solidified compounds with precipitate phases of 10 ⁇ m or less in size.
• the fine dispersion of Ni-Ni 3 P eutectic compounds with precipitate phases of 10 ⁇ m or less maintains uniform matrix strength, resulting in a uniform hardness for the coating. This not only improves wear resistance, but also helps to achieve both hardness and toughness, which was previously difficult to achieve.
• a uniformly hard structure with finely divided P compounds can be achieved in a coating by, for example, adding P and further remelting the coating at a temperature lower than 940°C.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Coating By Spraying Or Casting (AREA)
• Manufacture Of Metal Powder And Suspensions Thereof (AREA)
• Powder Metallurgy (AREA)

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Citations (2)

• 2024
  • 2024-03-26 JP JP2024048940A patent/JP7809740B2/ja active Active
• 2025
  • 2025-03-11 KR KR1020267022873A patent/KR20260116286A/ko active Pending
  • 2025-03-11 WO PCT/JP2025/009093 patent/WO2025204861A1/ja active Pending

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