Nickel-based alloy materials

Abstract

This invention relates to a nickel-based alloy material. By weight percentage, the nickel-based alloy material comprises: chromium: 20.00% to 22.50%, molybdenum: 11.50% to 14.50%, iron: 2.00% to 6.00%, copper: 2.10% to 6.00%, tungsten: 2.50% to 3.00%, cobalt: up to 2.50%, carbon: up to 0.10%, silicon: up to 1.00%, manganese: up to 0.50%, phosphorus: up to 0.02%, vanadium: up to 0.35%, with the balance being nickel and impurities less than 0.02%. The invention also relates to fibers having the above composition and a method for manufacturing such fibers.

Description

Technical Field

[0001] This invention generally relates to nickel-based alloy materials. In particular, it relates to nickel-chromium-molybdenum-copper alloys resistant to sulfuric acid and hydrochloric acid. The invention also relates to fibers having this alloy composition and processes for manufacturing such nickel-based alloy fibers. Background Technology

[0002] In the semiconductor manufacturing and processing, a significant number of steps involve reactions with sulfuric acid and hydrochloric acid. Materials resistant to sulfuric acid and hydrochloric acid are required for these reaction steps. Currently considered alloys for such applications include nickel-chromium-molybdenum alloys, which exhibit significantly superior corrosion resistance to sulfuric acid compared to iron-based alloys. Hastelloy C22 and Hastelloy C276 (“Hastelloy” is a trademark), nickel-based alloys containing 56%-59% nickel, 16%-27% chromium, and 16%-25% molybdenum, disclosed in patent documents such as JP 8-3666 and EP 2479301A, have already been used.

[0003] Chromium, copper, and molybdenum are known to each contribute to the corrosion resistance of nickel-based alloys to sulfuric acid. However, the use of these alloying additives is limited by considerations of thermal stability. In other words, if the solubility of these elements exceeds a significant amount, it is difficult to avoid the precipitation of harmful intermetallic phases in the metallographic structure. These can affect the manufacture of forged products and impair the performance of welded parts.

[0004] Seeking malleable alloys with higher resistance to sulfuric acid and hydrochloric acid. Summary of the Invention

[0005] The purpose of this invention is to provide a novel malleable alloy with higher resistance to sulfuric acid and hydrochloric acid.

[0006] Another object of the present invention is to provide corrosion-resistant fibers with novel alloy compositions and methods for manufacturing the same.

[0007] According to the present invention, a nickel-based alloy material is provided, comprising (in weight percentages) the following: chromium: 20.00% to 22.50%, molybdenum: 11.50% to 14.50%, preferably molybdenum: 12.5% ​​to 14.50%, iron: 2.00% to 6.00%, copper: 2.10% to 6.00%, tungsten: 2.50% to 3.00%, cobalt: up to 2.50%, carbon: up to 0.10%, for example, up to 0.03% or up to 0.01%, silicon: up to 1.00%, manganese: up to 0.50%, phosphorus: up to 0.02%, vanadium: up to 0.35%, with the balance being nickel and impurities less than 0.02%.

[0008] The nickel-based alloy material according to the present invention can be in any form. For example, the alloy material can be in a cast form. The alloy material can be in a powder metallurgy form. The alloy material can also be in fiber form. The alloy material can also be in the form of wire, foil, or mesh.

[0009] The current material can be manufactured using any known method for materials with similar compositions available in the prior art. According to the invention, a process for drawing bundles of metal wires having the alloy composition of the invention into fibers is particularly provided.

[0010] In the bundled drawing of metal fibers, many metal wires are bundled together for drawing. The individual metal wires are separated from each other, possibly by covering each wire with a suitable matrix material along its diameter. All the metal wires covered with matrix material are encapsulated in an encapsulating material. This bundle of encapsulated metal wires embedded in the matrix material is referred to below as a "composite wire". Once the composite wire is drawn to the desired diameter, the encapsulating and matrix materials are typically removed by leaching.

[0011] According to the present invention, copper or copper alloys are used as the matrix material to produce nickel-based alloy fibers. Metals (e.g., iron or copper) are used as the encapsulating material for manufacturing the fibers. Using copper or copper alloys as the matrix material is advantageous because copper or copper alloys have similar deformability to nickel-based alloy wires that must be drawn into nickel-based alloy fibers. During the drawing and annealing operations, the copper matrix is ​​consistent with the nickel-based alloy wire. The copper matrix has lower chemical resistance, allowing the nickel-based alloy fibers to detach from the copper matrix material fairly easily during the leaching process.

[0012] According to the present invention, a process for manufacturing nickel-based alloy fibers by bundle drawing is also provided. The process according to the present invention includes the following steps: (a) providing a nickel-based alloy metal wire composed of the following components (in weight percentages): 20.00% to 22.50% chromium, 11.50% to 14.50% molybdenum (preferably 12.50% to 14.50% molybdenum), 2.00% to 6.00% iron, 2.50% to 3.00% tungsten, a maximum of 5.00% copper (e.g., a maximum of 3.00% copper or a maximum of 1.00% copper), a maximum of 2.50% cobalt, and a maximum of 0.10% carbon (e.g., a maximum of 0.03%). (a) Containing a maximum of 0.01% (or 0.08%) of silicon, a maximum of 0.50% of manganese, a maximum of 0.02% of phosphorus, and vanadium: a maximum of 0.35%, with the balance being nickel and less than 0.02% of impurities; (b) Embedding a nickel-based alloy metal wire into a matrix material; (c) Encapsulating the embedded nickel-based alloy metal wire with an encapsulating material to form a composite wire; (d) Alternatingly reducing the diameter of the composite wire, heat-treating the diameter-reduced composite wire, and performing a final diameter reduction; (e) Providing nickel-based alloy metal fibers by removing the matrix material and encapsulating material from the composite wire. The heat treatment may be performed at a temperature ranging from 800°C to 1100°C for 0.05 minutes to 5 minutes.

[0013] In a preferred method, the nickel-based wire is embedded into a base material in a first step by applying a base material layer to each nickel-based wire. The base material comprises copper or a copper alloy. The thickness of this layer is, for example, between 1 μm and 2 mm. Possibly, the diameter of the coated wire is reduced by a drawing step. After the base material layer is applied to each metal wire, and possibly after drawing the coated wire, the wires can be bundled together to form a bundle. Subsequently, an encapsulating material comprising, for example, iron is applied around the bundle to form a composite wire.

[0014] Possibly, the method includes a step of heat-treating the composite wire before reducing its diameter.

[0015] Reducing the diameter of composite wire involves drawing the wire using any technique known in the art. Alternatively, diameter reduction can be achieved through a rolling operation.

[0016] Alternatively, the diameter of the composite wire can be reduced and then subjected to heat treatment. Diameter reduction may include several subsequent reduction processes, such as drawing operations on a wire drawing machine.

[0017] Removing the matrix material preferably involves leaching the composite wire with sulfuric acid or nitric acid.

[0018] During each heat treatment, the matrix material diffuses to a certain depth into the nickel base material, which depends primarily on the temperature used during the heat treatment.

[0019] According to the present invention, the initial nickel-based alloy wire contains less copper than the final nickel-based alloy fiber. Bundling and drawing of the nickel-based alloy wire is feasible. Intermediate heat treatment and / or final heat treatment performed between the two drawing steps allow the copper matrix material to diffuse into the nickel-based alloy wire. Therefore, the composition of the nickel-based alloy wire will be altered to some extent after heat treatment.

[0020] It is known in the prior art that copper and molybdenum have good resistance to sulfuric acid, but their combination can produce precipitates or sigma phases in nickel-based alloys. These sigma phases are detrimental to weldability and machinability. According to the invention, the initial nickel-based alloy wire contains less copper than the final drawn fiber. Therefore, the initial nickel-based alloy material has no problem with machinability. It can be observed from the prior art that the sigma phases generated by significant amounts of copper and molybdenum are detrimental to machinability. During the heat treatment of the composite wire, copper coated on the nickel-based alloy wire diffuses into the nickel-based alloy wire. A significant advantage of using copper as the matrix material for nickel-based alloy fibers is that the material has sufficient machinability during processing, and the diffusion of copper during heat treatment after wire diameter reduction further improves the corrosion resistance of the final nickel-based alloy fibers.

[0021] According to the present invention, the diameter of the composite wire is reduced at least once by a deformation amount of 4.5 or greater. The deformation amount ε is defined as the value of the logarithmic function of the ratio of the initial cross-section S1 to the final cross-section S2 of the composite wire:

[0022] ε = ln(S1 / S2)

[0023] The initial cross-section S1 refers to the cross-section of the composite wire measured after heat treatment and before further drawing. The final cross-section S2 refers to the cross-section of the composite wire after deformation (drawing) without intermediate heat treatment.

[0024] Reducing the number of annealing processes is possible because the composition of the nickel-based material allows for a high amount of deformation between two annealing processes. Preferably, this large reduction is used during the final reduction to provide the final diameter for the composite wire. As the subject of this invention, the nickel-based fibers thus obtained are most advantageous for controlling the diffusion and precipitation of copper on their surface. Heat treatment after the final drawing of the composite wire will increase the copper content in the nickel-based fibers, but precipitation will no longer affect the machinability of the composite wire. The nickel-based alloy material according to the invention contains a sigma phase. The nickel-based alloy fibers can have a sigma phase content ranging from 4% to 8% by volume. It is known in the prior art that the deformability and precipitation of the sigma phase in the composite wire can negatively affect the deformability of the composite wire. In the prior art, sigma phase precipitation is avoided due to the deterioration of machinability. Most surprisingly, it has been found that although the fibers produced according to the invention have sigma phase precipitation, the composite wire has sufficient machinability to be drawn to a small diameter.

[0025] After the final diameter reduction and before annealing, the copper distribution gradually decreases from the surface of the metal fiber to the bulk of the fiber. At a depth of 100 nm below the fiber surface, the copper content can range from greater than 2.1% (wt) to less than 10% (wt). Heat treatment may be performed after the final diameter reduction. After this final heat treatment, the nickel-based alloy fiber bundles were found to have substantially equal properties and a substantially uniform composition along the fiber length. Copper diffusion can be controlled by annealing during the drawing of the composite wire to its final diameter.

[0026] The uniformity of the nickel-based alloy fibers according to the present invention is an important advantage, because even small variations in the surface composition of the fibers can affect their properties. For example, the oxidation resistance and corrosion resistance of nickel-based alloy fibers depend on the compositional uniformity of the nickel-based fiber surface.

[0027] It has been found that the properties of the nickel-based alloy fibers according to the invention are more consistent throughout the entire length of the nickel-based alloy fibers, which are the subject of the invention. This compositional uniformity provides reliable and predictable fiber properties that allow for reliable and economical preventative replacement of such fibers and products comprising these nickel-based alloy fibers.

[0028] The initial nickel-based alloy wire can have a diameter between 100 μm and 20 mm. The nickel-based alloy fiber can have an equivalent diameter greater than 0.1 μm and less than 100 μm, and preferably has an equivalent diameter between 0.5 μm and 50 μm. The equivalent diameter is defined as the diameter of an imaginary circle whose surface area is the same as the surface area of ​​the cross-section of the nickel-based alloy fiber.

[0029] The silicon content in nickel-based alloy fibers can be limited to a maximum of 0.08% because there is no silicon contamination during fiber processing.

[0030] The nickel-based alloy fibers according to the present invention can be used in many applications. For example, they can be used for flocking on filter media, conductive fabrics, metal or polymer substrates.

[0031] Currently, when nickel-based alloy fibers are used in filter media, particularly in environments involving sulfuric and hydrochloric acids, such as gas filtration in semiconductor processing, improved corrosion resistance is required. The fibers, the subject of this invention, have been found to possess improved resistance to sulfuric and hydrochloric acid corrosion. The average corrosion rate of the material to hydrochloric acid is approximately 0.4 mils / year (MPY) to 0.6 mils / year. This can be attributed to the synergistic effect of copper and molybdenum, as well as the fiber manufacturing process that facilitates obtaining this composition.

[0032] According to another aspect of the invention, a filter medium is provided. The filter medium of the invention comprises at least one layer of a sintered mesh of powder or fibers. The powder or fibers are made of a nickel-based alloy material having the composition of the material of the invention. A filtration system is also provided, comprising a filter element having the filter medium according to the invention. Attached Figure Description

[0033] The invention will be described in more detail with reference to the accompanying drawings.

[0034] Figure 1 The corrosion resistance rate (MPY) of the nickel-based alloy fiber, which is the subject of this invention, is shown compared to currently known nickel-based alloy materials with similar compositions but different copper and / or molybdenum contents. Detailed Implementation

[0035] Table 1 shows the composition of nickel-based alloy fiber samples A and B, and nickel-based alloy sample material X according to the present invention.

[0036] The nickel-based alloy fibers, the subject of this invention, can be provided using the following preferred process. Nickel-based wires with a diameter between 0.5 mm and 1.5 mm (e.g., 1.4 mm) and having a composition according to Example X of nickel-based alloy material X in Table 1 are provided. These nickel-based alloy wires are coated with an electrolytic coating, for example, having a copper or copper alloy layer. Preferably, the layer has a thickness ranging from 3 μm to 100 μm, for example, 5 μm. Typically, 50 to 2000 nickel-based alloy wires are bundled into a composite wire. After reducing the diameter of the composite wire and removing the encapsulating material and matrix material, the resulting nickel-based alloy fiber bundle, the subject of this invention, comprises 50 to 2000 nickel-based alloy fibers. Most preferably, 90 to 1000 nickel-based alloy wires are bundled. Possibly, the diameter of the nickel-based wire with the coating layer is reduced to the range of 0.1 mm to 1 mm, for example, 0.35 mm. Several (e.g., 1000) coated wires with a reduced diameter are encapsulated in a material such as an iron sheath, thus providing composite wires with diameters ranging from 5 mm to 15 mm.

[0037] Table 1. Composition (by weight percentage) of nickel-based alloy fiber samples A and B and nickel-based alloy sample material X according to the present invention.

[0038]

[0039] The composite wire is alternately reduced at several reduction rates ε (e.g., ε1, ε2) greater than 0.5 (e.g., 1.5), and then annealed in a temperature range of 800°C to 1100°C (e.g., 1030°C). This heat treatment is performed for 0.05 minutes to 5 minutes (e.g., 2 minutes). The final reduction reduces the diameter of the composite wire by ε greater than 4.5. This final reduction provides the final diameter of the composite wire. Finally, the matrix material and encapsulating material are removed by pickling with an acid (e.g., nitric acid). Nickel-based alloy fibers with diameters ranging from, for example, 0.5 μm to 5 μm, exhibiting copper diffusion on the nickel-based alloy fibers are obtained.

[0040] Sigma phases were found to be uniformly distributed in the composite wire. The composition of these sigma phases differs from that of the nickel-based alloy fiber matrix. Typically, the sigma phases contain more molybdenum and tungsten than the nickel-based alloy fiber matrix. The sigma phases may contain more than 20% (wt) of molybdenum, for example, 25% (wt) to 40% (wt), and more than 5% (wt) of tungsten, for example, 6% (wt) to 8% (wt). Examples of sigma phase compositions are listed below in Table 2. The sigma phases in the materials of this invention specifically contain copper, for example, 1% (wt) to 3% (wt) or 1% (wt) to 2% (wt), while in the remaining bulk of the nickel-based alloy fiber (hereinafter, the remaining bulk refers to the bulk region excluding the sigma phases), the copper content ranges from 3% (wt) to 7% (wt), for example, 3% (wt) to 5% (wt). The copper content in the sigma phases is less than that in the remaining bulk of the nickel-based alloy material. The sigma phases are uniformly distributed in the nickel-based alloy fibers. This distinguishes the material of the present invention from existing nickel-based alloy sample material X (Table 1) and another reference nickel-based alloy foil having a composition similar to material X. As shown in Table 2, the reference material does not contain copper in its sigma phase.

[0041] Table 2. Examples of sigma phase composition (in weight percentage) measured by energy-dispersive X-ray spectroscopy.

[0042]

[0043] In one embodiment, fibers having the components of the present invention were drawn to a final diameter of 8 μm, and it was found that the sigma phase therein was about 7% (by volume). As another example, nickel-based alloy fibers of the present invention were drawn to 1.5 μm, and contained 5.5% (by volume) of the sigma phase.

[0044] Compared to similar currently known nickel-based alloy materials, the nickel-based alloy fibers, the subject of this invention, exhibit improved resistance to hydrochloric acid corrosion. Figure 1 Examples of hydrochloric acid corrosion resistance rates measured on nickel-based alloy fibers (sample A and sample B), which are the subject of this invention, and on nickel-based alloy materials with similar compositions (from patent EP2479301) that are currently known.

[0045] Besides differences in copper and / or molybdenum content, such as Figure 1 The reference materials listed herein have similar compositions to the materials of this invention. Figure 1 In the figure, the copper content of the material is represented by the horizontal axis, and the molybdenum content is represented by the vertical axis. Figure 1 The bubbles in the image represent the corrosion resistance rates of various materials to hydrochloric acid.

[0046] The nickel-based alloy fiber sample A of the present invention exhibits a hydrochloric acid corrosion resistance rate of 0.4 MPY, while sample B of the present invention exhibits a hydrochloric acid corrosion resistance rate of 0.6 MPY. As shown in Table 1, sample X of the reference material exhibits a hydrochloric acid corrosion resistance rate of 1.3 MPY. Figure 1 As shown, other reference materials with similar compositions but with low copper or low molybdenum content all exhibit higher corrosion resistance rates than the nickel-based alloy fibers of this invention.

Claims

1. A nickel-based alloy material in fibrous form, wherein, by weight percentage, the nickel-based alloy material comprises the following: Chromium: 20.00% to 22.50% Molybdenum: 11.50% to 14.50% Iron: 2.00% to 6.00% Copper: 2.10% to 6.00% Tungsten: 2.50% to 3.00% Cobalt: Maximum 2.50% Carbon: Maximum 0.10% Silicon: Maximum 1.00% Manganese: Maximum 0.50% Phosphorus: Maximum 0.02% Vanadium: Maximum 0.35%, The balance is nickel and less than 0.02% impurities, wherein the nickel-based alloy material contains a sigma phase, and the copper content in the sigma phase is less than the copper content in the remaining portion of the nickel-based alloy material.

2. The nickel-based alloy material according to claim 1, wherein, The sigma phase is in the range of 4 (volume)% to 8 (volume)%.

3. The nickel-based alloy material according to claim 1 or 2, wherein, The nickel-based alloy fiber has an equivalent diameter greater than 0.1 μm and less than 100 μm.

4. The nickel-based alloy material according to claim 3, wherein, The nickel-based alloy fiber has a silicon content of up to 0.08%.

5. The nickel-based alloy material according to claim 3, wherein, The distribution of copper gradually decreases from the surface of the nickel-based alloy fiber to the bulk of the nickel-based alloy fiber, wherein the copper content is in the range of greater than 2.1% (wt) and less than 10% (wt) at a depth of 100 nm below the surface of the fiber.

6. The nickel-based alloy material according to claim 4, wherein, The distribution of copper gradually decreases from the surface of the nickel-based alloy fiber to the bulk of the nickel-based alloy fiber, wherein the copper content is in the range of greater than 2.1% (wt) and less than 10% (wt) at a depth of 100 nm below the surface of the fiber.

7. A filter medium comprising at least one layer, the layer being a sintered fibrous mesh, the fibers being fibers according to any one of claims 1 to 6.

8. A filtration system comprising a filter element having a filter medium according to claim 7.

9. A process for manufacturing nickel-based alloy fibers by bundle drawing, the process comprising the following steps: a. Provide nickel-based alloy metal wire, which, by weight percentage, comprises the following: Chromium: 20.00% to 22.50% Molybdenum: 11.50% to 14.50% Iron: 2.00% to 6.00% Tungsten: 2.50% to 3.00% Copper: Maximum 5.00% Cobalt: Maximum 2.50% Carbon: Maximum 0.10% Silicon: Maximum 0.08% Manganese: Maximum 0.50% Phosphorus: Maximum 0.02% Vanadium: Maximum 0.35%, The balance consists of nickel and less than 0.02% impurities; b. Embedding nickel-based alloy metal wire into copper or copper alloy as the base material; c. Encapsulate the embedded nickel-based alloy metal wire with an encapsulating material to form a composite wire; d. Alternately reduce the diameter of the composite wire by heat-treating the diameter-reduced composite wire at a temperature ranging from 800°C to 1100°C for 0.05 minutes to 5 minutes to allow copper from the base material to diffuse into the nickel-based alloy metal wire, and then perform a final diameter reduction. e. Providing nickel-based alloy fibers by removing the matrix material and the encapsulating material from the composite wire, wherein the nickel-based alloy fibers contain a sigma phase, wherein the copper content in the sigma phase is less than the copper content in the remainder of the nickel-based alloy fibers.

10. The process according to claim 9, wherein, The process includes heat treatment following the final diameter reduction.

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