Metal silicide and its manufacturing method, alloy material and its manufacturing method, heating element, electrical resistor

Abstract

A metal silicide according to an embodiment of the present invention comprises an element M, said metal silicide containing 0.001-10 mass% of an element X, wherein the element X is one or more elements selected from the group consisting of Sn, Ag, Au, Bi, Pb, and Cu, and the element M is Mo or W.

Description

[Technical Field]

[0001] The present invention relates to a metal silicide and a method for producing the same, an alloy material and a method for producing the same, a heating element, and an electric resistor. This application claims priority based on Japanese Patent Application No. 2022-064491, filed on April 8, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] Molybdenum-based alloys (Mo-based alloys) are known as materials with excellent heat resistance at high temperatures. However, Mo-based alloys have the disadvantage of easily oxidizing at high temperatures. Therefore, when using Mo-based alloys in high-temperature environments, it is essential to form a protective film on the surface to prevent oxidation.

[0003] MoSi2 alloy (intermetallic compound) is known as an effective material for such a protective film (for example, Patent Document 1). MoSi2 alloy generates an SiO2 film on the surface, which can prevent oxidation from progressing into the interior of the Mo-based alloy. MoSi2 alloy can be used in oxidizing atmospheres at ultra-high temperatures, for example, exceeding 1500°C, and is therefore extremely useful as a material with high-temperature oxidation resistance.

[0004] The pack cementation method is a commonly known method for forming a MoSi2 film on the surface of a Mo-based alloy. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-17977 [Non-patent literature]

[0006] [Non-Patent Document 1] Jia Sun et al., “Effect of filler on the oxidation protective ability of MoSi2 coating for Mo substrate by halide activated pack cementation” Materials & Design Volume 92, 15 February 2016, Pages 602-609. [Non-patent document 2] S.Majumdar “Formation of MoSi2 and Al doped MoSi2 coatings on molybdenum base TZM (Mo-0.5Ti-0.1Zr-0.02C) alloy” Surface and Coatings Technology Volume 206, Issue 15, 25 March 2012, Pages 3393-3398. Summary of the Invention [Problem to be solved by the invention]

[0007] However, while the commonly used pack cementation method can stably form MoSi2 films, it has the drawback of requiring harsh processing conditions. Specifically, the pack cementation method requires a very long processing time, for example, about 10 to 18 hours, and furthermore, processing must be performed at a very high temperature range of about 1100 to 1300°C (see Non-Patent Documents 1 and 2). Therefore, the load on the equipment used has also been an issue.

[0008] In addition, the pack cementation method is a process in which the metal material (substrate) to be silicified is embedded in a crucible filled with powder for pack cementation and heated at a predetermined temperature to silicify the surface of the substrate. Therefore, temperature unevenness often occurs within the surface of the substrate, and the thickness of the resulting silicified film may not be uniform.

[0009] In light of this background, there is a demand for a method for producing MoSi2 alloys, including a method for forming a MoSi2 film on the surface of a Mo-based alloy, that can obtain MoSi2 alloys with excellent high-temperature oxidation resistance and improve production efficiency by shortening the high-temperature treatment time and lowering the treatment temperature.

[0010] In view of the above circumstances, an object of the present invention is to provide a metal silicide having excellent oxidation resistance and a method for producing the same, an alloy material and a method for producing the same, a heating element, and an electric resistor. [Means for solving the problem]

[0011] The present inventors first focused on the composition of the Si bath in which the Mo-based alloy is immersed, and investigated the design of the bath composition from the viewpoint of improving the high-temperature oxidation resistance of the resulting MoSi2 alloy and improving the manufacturing efficiency. As a result, they found that by using a molten Sn-Si alloy bath containing Si in the Sn bath, MoSi2 alloy with excellent high-temperature oxidation resistance can be obtained, and the treatment time (immersion time) and treatment temperature (bath temperature) can be shortened. Furthermore, when a similar investigation was carried out using a tungsten-based alloy (W-based alloy) as another heat-resistant material, it was found that when a W-based alloy was used, it also had excellent high-temperature oxidation resistance. W It was found that Si2 alloy can be obtained and the manufacturing efficiency can be improved.

[0012] Furthermore, when the composition of the Si bath was investigated, it was found that, in addition to Sn, Ag, Au, Bi, Pb and Cu could also be added to the bath to have the same effect as described above.

[0013] The present invention has been made based on the above findings, and the gist of the present invention is as follows. [1] The metal silicide according to the first embodiment of the present invention is As the main ingredient element M and Si The metal silicide contains, in mass %, an element X: 0.001 to 10%, wherein the element X is one or more selected from the group consisting of Sn, Bi, and Pb, and the element M is Mo or W. [2] In the metal silicide described in the above [1], the element X may be Sn.

[0014] [3] A method for producing a metal silicide according to a second embodiment of the present invention is the method for producing a metal silicide according to the above [1], and includes an immersion step of immersing a Mo-based alloy material or a W-based alloy material in a treatment bath containing Si and the element X, the bath temperature of the treatment bath being 200 to 1500°C, and the composition of the treatment bath containing 0.001 to 99.99 mass% of Si and the remainder being the element X. [4] In the method for producing a metal silicide according to the above [3], the element X may be Sn. [5] The method for producing a metal silicide according to the above [3] or [4] may further include a pre-forming step of forming the Mo-based alloy material or the W-based alloy material before the immersion step.

[0015] [6] An alloy material according to a third embodiment of the present invention comprises a base material and a film made of a metal silicide containing an element M formed on a surface of the base material, the metal silicide containing, by mass %, 0.001 to 10% of an element X, and the element X is Sn 、B i and P b or The element M is one or more selected from the group consisting of the elements M and W, and the base material is a Mo-based alloy material or a W-based alloy material. [7] In the alloy material described in [6] above, the element X may be Sn.

[0016] [8] A fourth embodiment of the present invention relates to a method for manufacturing an alloy material, which is the method for manufacturing an alloy material described in [6] above, and further includes a dipping step of dipping the base material in a treatment bath containing Si and the element X, wherein the temperature of the treatment bath is 200 to 1500°C, and the composition of the treatment bath contains 0.001 to 99.99 mass% of Si, with the remainder being the element X. [9] In the method for producing an alloy material described in [8] above, the element X may be Sn.

[10] The method for producing an alloy material according to the above [8] or [9] may further include a pre-forming step of forming the base material before the immersion step.

[0017]

[11] A heating element according to a fifth embodiment of the present invention includes the metal silicide described in [1] or [2] above.

[12] An electric resistor according to a sixth embodiment of the present invention contains the metal silicide according to the above [1] or [2]. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a metal silicide having excellent oxidation resistance and a manufacturing method thereof, an alloy material and a manufacturing method thereof, a heating element, and an electric resistor. Furthermore, the manufacturing method of the metal silicide and the manufacturing method of the alloy material of the present invention can shorten the processing time and lower the processing temperature, thereby significantly improving the manufacturing efficiency. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a cross-sectional schematic diagram of the immersion device used in this example. [Figure 2] FIG. 2 is an SEM image of the surface layer of the Mo alloy material in this example. [Figure 3] FIG. 3 is an SEM image of the surface layer of the Mo alloy material in this example. [Figure 4] FIG. 4 is an SEM image of the surface layer of the Mo alloy material in this example. [Figure 5] FIG. 5 is an SEM image of the surface layer of the Mo alloy material in this example. [Figure 6] FIG. 6 is a photograph showing the results of the high-temperature oxidation test in this example. [Figure 7] FIG. 7 shows an SEM image of the sample after the high-temperature oxidation test and the element mapping results in this example. [Figure 8] FIG. 8 is an SEM image of the sample after the high-temperature oxidation test in this example. [Figure 9]FIG. 9 is an SEM image of the surface layer of the Mo alloy material in Example 2. [Figure 10] FIG. 10 is a diagram showing the element mapping results in Example 2. [Figure 11] FIG. 11 shows the diffraction peaks obtained by XRD in Example 2. [Figure 12] FIG. 12 is an SEM image of the surface layer of the Mo alloy material in Example 3. [Figure 13] FIG. 13 is a diagram showing the element mapping results in Example 3. [Figure 14] FIG. 14 shows diffraction peaks obtained by XRD in Example 4. [Figure 15] FIG. 15 is an SEM image of the surface layer of the W alloy material in Example 5. [Figure 16] FIG. 16 is a diagram showing the element mapping results in Example 5. [Figure 17] FIG. 17 shows the diffraction peaks obtained by XRD in Example 5. [Figure 18] FIG. 18 is an SEM image of a thickness cross section of Mo silicide in Example 6. [Figure 19] FIG. 19 is a diagram showing the element mapping results in Example 6. DETAILED DESCRIPTION OF THE INVENTION

[0020] The following describes the metal silicide and its manufacturing method, the alloy material and its manufacturing method, the heating element, and the electrical resistor according to the present embodiment. However, the present invention is not limited to the configurations disclosed in the present embodiment, and various modifications are possible within the scope of the present invention.

[0021] [Metal silicides] First, the metal silicide of this embodiment will be described in detail below.

[0022] The metal silicide of this embodiment is a metal silicide containing Mo or W (element M). The metal silicide also contains, as element X, one or more elements selected from the group consisting of Sn, Ag, Au, Bi, Pb, and Cu in a total amount of 0.001 to 10 mass %.

[0023] The metal silicide of this embodiment does not substantially contain any components other than Si, element M, and element X. Here, "substantially free" means that impurities are present to a degree that does not impair the effects or characteristics of the present invention. Impurities are components that are mixed in due to various factors in the manufacturing process, including raw materials, when industrially manufacturing an alloy material, and also include components that are unavoidably mixed in. Note that the lower the impurity content, the more desirable it is, but a total of 0.001 mass% or less based on the entire metal silicide is preferred.

[0024] (Element M: Mo or W) The metal silicide of this embodiment is mainly composed of Si and molybdenum (Mo) or tungsten (W). That is, the metal silicide of this embodiment is essentially MoSi2 or WSi2, but as will be described later, these metal silicides contain an element X such as Sn.

[0025] The metal silicide of this embodiment may be Mo5Si3, W5Si3, Mo3Si, W3Si, or the like, in addition to MoSi2 and WSi2.

[0026] (Element X) The metal silicide contains 0.001 to 10 mass% in total of one or more elements selected from the group consisting of Sn, Ag, Au, Bi, Pb, and Cu as the element X. That is, the metal silicide of this embodiment is in a form in which the element X is solid-dissolved in MoSi2, for example. These elements X are components derived from a "molten X-Si alloy bath" in which the element X is added to a molten Si bath, which will be described later. That is, by producing a metal silicide using a "molten X-Si alloy bath" which will be described later, the element X (e.g., Sn) in the bath penetrates into the metal silicide (e.g., MoSi2), resulting in "a form in which the element X is dissolved in MoSi2."

[0027] A trace amount of element X in a metal silicide does not affect the properties. However, an excessively high content of element X may result in the formation of another phase in the metal silicide. Therefore, the total content of element X is set to 10% by mass or less, preferably 5% by mass or less, and more preferably 3% by mass or less. Meanwhile, in the method for producing a metal silicide of this embodiment, a molten bath containing element X is used to improve the efficiency of the production process. To achieve this effect, a certain concentration or more of element X must be added to the bath. In other words, the lower limit of the amount of element X in the resulting metal silicide must be a certain amount or more from the perspective of improving the efficiency of the production process. Specifically, the total content of element X in the metal silicide is 0.001% by mass or more, preferably 0.01% by mass or more, and more preferably 0.1% by mass or more.

[0028] The content of the metal silicide in the molten X-Si alloy bath can be controlled by adjusting the immersion time, bath temperature, and bath composition.

[0029] The element X contained in the metal silicide is one or more elements selected from the group consisting of Sn, Ag, Au, Bi, Pb, and Cu. That is, two or more of these elements may be contained. In order to ensure stable high-temperature oxidation resistance and to achieve a balanced improvement in manufacturing efficiency, the element X is preferably Sn. That is, the "molten X-Si alloy bath" described below is preferably a molten Sn-Si alloy bath.

[0030] [Alloy material] Next, the alloy material according to this embodiment will be described.

[0031] The alloy material of this embodiment uses a Mo-based alloy material or a W-based alloy material as a base material, and has a film (metal silicide film) made of the metal silicide according to this embodiment on the base material. That is, similar to the conventional pack cementation method, an alloy material having a metal silicide film formed on the base material is obtained by immersing a Mo-based alloy material or a W-based alloy material in a "molten X-Si alloy bath."

[0032] The Mo-based alloy material as the base material may be an alloy material in which desired alloying elements are contained in Mo, or may be a material of Mo alone (e.g., a metal Mo plate), depending on the intended use. Similarly, the W-based alloy material as the base material may be an alloy material in which desired alloying elements are contained in W, or may be a material of W alone (e.g., a metal W plate), depending on the intended use.

[0033] According to the manufacturing method of the alloy material according to the present embodiment, which will be described later, element X (such as Sn) in the bath may penetrate into the base material during immersion. The longer the immersion time, the greater the amount of penetration of element X. The penetration of element X into the base material is undesirable from the viewpoint of lowering the melting point of the base material. Therefore, it is desirable that the average concentration of element X at a depth of 10 μm from the surface of the base material (the interface with the metal silicide film) be 1 mass % or less.

[0034] The concentration of element X at a depth of 10 μm from the surface of the base material (interface with the metal silicide film) can be controlled by adjusting the immersion time in the molten X-Si alloy bath and the bath temperature.

[0035] [Method for manufacturing metal silicide] [Method of manufacturing alloy materials] Next, the method for producing a metal silicide and the method for producing an alloy material according to this embodiment will be described in detail below.

[0036] The method for producing a metal silicide of this embodiment includes an immersion step of immersing a Mo-based alloy or a W-based alloy as a base material in a treatment bath (molten X-Si alloy bath) containing Si and the aforementioned element X.

[0037] (Soaking process) First, a Mo-based alloy material (including Mo plate) or a W-based alloy material (including W plate) is prepared as a base material and immersed in the following treatment bath (molten X-Si alloy bath).

[0038] <Treatment bath> ·Bath temperature: 200℃~1500℃ Bath composition: Contains 0.001 to 99.99 mass % of Si, with the remainder being element X.

[0039] The temperature of the treatment bath is set within the range of 200° C. to 1500° C. If the temperature of the treatment bath is too low, there is a risk that Si will not melt into the element X. Therefore, the temperature of the treatment bath is set to 200° C. or higher, and preferably 400° C. or higher. On the other hand, the inventors have investigated the relationship between the temperature of the treatment bath and the film formation state and film formation rate of the metal silicide film, and as a result have found that an excessively high temperature of the treatment bath is undesirable. Specifically, it has been found that the lower the temperature of the treatment bath, the higher the film formation rate can be. The mechanism by which the film formation rate increases as the treatment bath temperature decreases is not clear, but it is presumed to be due to the following reasons.

[0040] The lower the temperature of the treatment bath, the easier it is for element X to dissolve in the metal silicide film, and furthermore, vacancies are generated in the crystal structure of the metal silicide film, which makes it easier for Si to diffuse in the film. Thus, it is thought that the lower the temperature of the treatment bath, the more the diffusion of Si in the film is promoted, and as a result, the film formation rate of the metal silicide film increases.

[0041] For the above reasons, in this embodiment, it is effective to avoid an excessive increase in the temperature of the treatment bath. Specifically, the treatment bath temperature is set to 1500°C or less, preferably 1000°C or less, and more preferably 900°C or less.

[0042] The composition of the treatment bath contains 0.001 to 99.99 mass% Si, with the remainder being the element X. However, when designing the composition of the treatment bath, it is desirable to take into consideration the solubility of Si in the molten element X at a certain temperature of the treatment bath. Therefore, the composition of the treatment bath preferably contains 0.01 to 50 mass% Si, with the remainder being the element X, and more preferably contains 0.1 to 20 mass% Si, with the remainder being the element X.

[0043] The treatment bath in this embodiment may be in a state where the element X and Si in the bath are all melted, or may be in a state where some of them remain as solids.

[0044] The immersion time in the immersion step may be appropriately determined depending on the target dimensions, such as the target metal silicide film. Furthermore, in the manufacturing method of this embodiment, as described above, the film formation rate can be increased by adding element X to the treatment bath. While pack cementation, one of the conventional methods, requires immersion for approximately 10 to 20 hours, the immersion time can be shortened in this embodiment by adding element X to the treatment bath. However, if the immersion time is too short, the thickness of the metal silicide film will be insufficient, which may result in a deterioration in the high-temperature oxidation resistance of the resulting metal silicide film (or alloy material). From this perspective, the immersion time is preferably 1 minute or longer.

[0045] Here, the metal silicide according to this embodiment can be obtained by forming a sufficiently thick metal silicide film in the immersion step. That is, the metal silicide according to this embodiment can be obtained by immersing a Mo-based alloy or W-based alloy as a base material in a bath and causing a silicidation reaction across the entire thickness of the base material. On the other hand, the alloy material according to this embodiment can be produced by adjusting the immersion time and leaving a portion of the base material.

[0046] The atmosphere in the immersion step is not particularly limited, but from the viewpoint of preventing oxidation, an inert gas atmosphere is preferable. Examples of inert gas include argon (Ar) gas and nitrogen (N2) gas.

[0047] The base material may be immersed once or multiple times. From the viewpoint of more stably forming a metal silicide film of sufficient thickness, the number of immersions is preferably two or more. When immersing multiple times, the immersion conditions for each immersion may be the same or may be varied as long as they are not within the above range. After the immersion step is completed, element X remaining on the surface of the formed film may be removed using an acid or the like.

[0048] (Pre-forming process) In this embodiment, a pre-forming step of shaping the Mo-based alloy material or W-based alloy material as the base material may be further included before the above-mentioned immersion step. That is, the Mo-based alloy material or W-based alloy material immersed in the treatment bath may have various shapes. For example, when the metal silicide of this embodiment is provided on the surface layer of a part having a desired shape, the Mo-based alloy material or W-based alloy material as the base material may be shaped into a shape close to the final shape of the part before the immersion step, and then the shaped base material may be subjected to the immersion step. By undergoing such a pre-forming step, an alloy material having a desired shape can be obtained. Furthermore, by shaping the base material in advance, it is possible to obtain metal silicides having various shapes. Generally, metal silicides are difficult to process due to their brittleness. However, as in the present embodiment, the pre-forming process allows the base material, which is easy to process, to be formed into a predetermined shape close to the final shape, making it possible to obtain an alloy material or metal silicide having a desired shape.

[0049] The shape of the base material in the preforming step is not limited, and may be any of a block, plate, wire, and particle shape. When forming the base material into a block (bulk material with a complex shape), cutting or casting can be applied. When forming the base material into a plate, pressing, rolling, bending, or drilling can be applied. When forming the base material into a wire, bending, twisting, etc. can be applied. When the base material is made of fine particles (for example, powder), a molded product formed by 3D printing using the fine particles, compression molding, or powder sintering can be subjected to the immersion process. Note that molded products using fine particle base materials can be applied to both dense and non-dense materials (with internal voids) with complex shapes (or simple shapes).

[0050] By the above method, metal silicides and alloy materials having excellent high-temperature oxidation resistance can be produced.

[0051] The manufacturing method according to this embodiment is a method of immersing a Mo-based alloy or W-based alloy, which has a relatively high density, as a base material in a molten X-Si alloy bath. That is, when the above-described immersion method is applied to a Mo-based alloy or W-based alloy as a base material, stable operation is possible, and metal silicides and alloy materials with little quality variation can be manufactured. Furthermore, since the manufacturing method according to this embodiment is an immersion method using a molten X-Si alloy bath, it is possible to improve the uniformity of the resulting metal silicide film compared to the pack cementation method using powder. Furthermore, in the manufacturing method according to this embodiment, metal silicides and alloy materials can be manufactured simply by pulling up the Mo-based alloy material or W-based alloy material serving as the base material from the molten X-Si alloy bath after the immersion step. Compared with the pack cementation method, which requires the product to be removed from the powder, metal silicides and alloy materials can be manufactured more easily. Furthermore, the powder used in the pack cementation method cannot be reused for production. In the production method according to this embodiment, the molten X-Si alloy bath remaining after the Mo-based alloy or W-based alloy base material is pulled up can be reused.

[0052] [Application] The metal silicide and alloy material of this embodiment has excellent resistance to high-temperature oxidation and is therefore suitable for use as various heating elements and electrical resistors. [Example]

[0053] The present invention will now be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples as long as they do not depart from the gist of the invention. In other words, the present invention naturally includes other examples, embodiments, etc. within the scope of the technical concept of the present invention.

[0054] Example 1 First, using the immersion apparatus shown in Figure 1, Sn and Si were placed in a crucible (made of Al2O3) under an Ar gas atmosphere and heated with a heater to prepare a treatment bath (molten Sn-Si alloy bath) with a composition of 98.8Sn-1.2Si (mass%). Next, the bath temperature and immersion time of the adjusted treatment bath were changed as follows, and a metal Mo plate (length 50 mm, width 10 mm, thickness 1 mm) was immersed in the bath to form a Mo silicide film on the Mo plate, thereby obtaining a Mo alloy material.

[0055] After the Mo silicide film was formed, the immersed Mo plate was taken out of the treatment bath, and after removing any unnecessary bath that had adhered thereto, the Mo alloy material was taken out of the immersion apparatus and recovered.

[0056] ·Bath temperature: 700℃, 800℃, 900℃, 1000℃ Soaking time: 15 minutes, 30 minutes, 60 minutes

[0057] The surface layer (including the Mo silicide film) of each of the obtained Mo alloy materials was observed using an SEM. The results are shown in Figures 2 to 5. In addition, energy dispersive X-ray analysis (EDS analysis) was performed on regions 1 to 6 of each of the SEM images in Figures 2 to 5 to investigate the composition of each region. The results are shown in Tables 1 to 4.

[0058] As shown in FIGS. 2 to 5 and Tables 1 to 4, it was found that the Mo alloy material produced by applying the present invention had a Mo silicide film formed on the surface layer with a sufficient thickness.

[0059] [Table 1]

[0060] [Table 2]

[0061] [Table 3]

[0062] [Table 4]

[0063] Furthermore, a high-temperature oxidation test was conducted on each of the Mo alloy materials obtained, using samples with a bath temperature of 1000°C and an immersion time of 60 minutes, to investigate their high-temperature oxidation resistance. Specifically, first, 10 mm square samples for the oxidation test were cut out from the samples. The exposed portions of the cut samples, where the base material (Mo plate) was present, were covered with ceramic paste to prevent the effects of the high-temperature oxidation test. Next, the obtained samples were placed in a furnace (atmosphere: air) for the oxidation test, heated to 1150°C, held for 120 minutes, and then slowly cooled to room temperature. The heating rate was 20°C / min.

[0064] Photographs of the sample before and after the high-temperature oxidation test are shown in Figures 6(a) and 6(b). Figure 6(a) shows a photograph of the sample before the test, and Figure 6(b) shows a photograph of the sample after the test. Figure 7 shows the SEM observation results (SEM image) and element distribution analysis (element mapping) of the sample after the high-temperature oxidation test. Figure 8 also shows energy dispersive X-ray analysis (EDS analysis) performed on regions 1 to 3 of the SEM image shown in Figure 7 to investigate the composition of each region. The results are shown in Table 5.

[0065] As is clear from Figures 6(a) and 6(b) and Figures 7 and 8, the Mo alloy material produced by applying the present invention has a clean Mo silicide film that does not peel off even after the high-temperature oxidation test, and this shows that the Mo alloy material produced by applying the present invention has excellent high-temperature oxidation resistance.

[0066] [Table 5]

[0067] Example 2 Next, in the same manner as in Example 1, using the immersion apparatus shown in FIG. 1, Bi and Si were placed in a crucible (made of AlO) under an Ar gas atmosphere and heated with a heater to prepare a treatment bath (molten Bi-Si alloy bath) with a composition of 98.0% Bi-2.0% Si (mass %). Next, the bath temperature and immersion time of the adjusted treatment bath were changed as follows, and a metal Mo plate (length 50 mm, width 10 mm, thickness 1 mm) was immersed in the bath to form a Mo silicide film on the Mo plate, thereby obtaining a Mo alloy material.

[0068] After the Mo silicide film was formed, the immersed Mo plate was taken out of the treatment bath, and after removing any unnecessary bath that had adhered thereto, the Mo alloy material was taken out of the immersion apparatus and recovered.

[0069] <Molten Bi-Si alloy bath> ·Bath temperature: 1000℃ Soaking time: 15 minutes, 60 minutes

[0070] Of the Mo alloy materials obtained, the Mo alloy material immersed for 15 minutes was subjected to SEM observation of the surface layer (including the Mo silicide film) and element distribution analysis (element mapping). The results are shown in Figures 9 and 10. Furthermore, energy dispersive X-ray analysis (EDS analysis) was carried out on each of region 1 and region 2 of the SEM image in Figure 9 to investigate the composition of each region. The results are shown in Table 6.

[0071] Further, the diffraction peaks of each of the obtained Mo alloy materials were obtained by X-ray diffraction (XRD). Specifically, XRD measurement was performed on the surface of each of the obtained Mo alloy materials. The XRD measurement was performed using CuKα as a radiation source, in the range of 2θ from 10° to 90°, with a measurement interval of 0.02° and a measurement speed of 5° / min. The results are shown in Figure 11.

[0072] As shown in Figures 9 to 11 and Table 6, it was found that a Mo silicide film was formed on the surface layer of the Mo alloy materials produced by applying the present invention. As shown in Figure 11, the presence of Mo5Si3 was confirmed by XRD measurement of the surface of each Mo alloy material obtained. However, as shown in Table 6, Mo5Si3 was not detected in EDS analysis of region 1. This is thought to be because the thickness of the Mo5Si3 layer formed on the surface layer of the Mo alloy material was very small. However, as mentioned above, the formation of Mo5Si3 on the surface layer of the Mo alloy material in Example 2 was confirmed by XRD measurement (Figure 11).

[0073] [Table 6]

[0074] Example 3 Next, in the same manner as in Example 1, using the immersion apparatus shown in FIG. 1, Cu and Si were placed in a crucible (made of Al2O3) under an Ar gas atmosphere and heated with a heater to prepare a treatment bath (molten Cu-Si alloy bath) with a composition of 73.5% Cu-26.5% Si (mass %). Next, the bath temperature and immersion time of the adjusted treatment bath were changed as follows, and a metal Mo plate (length 50 mm, width 10 mm, thickness 1 mm) was immersed in the bath to form a Mo silicide film on the Mo plate, thereby obtaining a Mo alloy material.

[0075] After the Mo silicide film was formed, the immersed Mo plate was taken out of the treatment bath, and after removing any unnecessary bath that had adhered thereto, the Mo alloy material was taken out of the immersion apparatus and recovered.

[0076] <Molten Cu-Si alloy bath> ·Bath temperature: 1000℃ Soaking time: 15 minutes, 30 minutes, 60 minutes

[0077] Of the Mo alloy materials obtained, the Mo alloy material immersed for 15 minutes was subjected to SEM observation of the surface layer (including the Mo silicide film) and element distribution analysis (element mapping). The results are shown in Figures 12 and 13. Furthermore, energy dispersive X-ray analysis (EDS analysis) was carried out on each of regions 1 to 3 in the SEM image of Fig. 12 to investigate the composition of each region. The results are shown in Table 7.

[0078] 12, 13, and Table 7, it was found that a Mo silicide film was formed on the surface layer of the Mo alloy material produced by applying the present invention. Note that, as shown in Fig. 12 and Fig. 13, when a Cu-Si phase derived from the bath that was not completely removed and remained on the outermost surface of the alloy material is formed, the phase can be removed mechanically, for example.

[0079] [Table 7]

[0080] Example 4 Next, in the same manner as in Example 1, using the immersion apparatus shown in FIG. 1, Pb and Si were placed in a crucible (made of Al2O3) under an Ar gas atmosphere and heated with a heater to prepare a treatment bath (molten Pb-Si alloy bath) with a composition of 98.0% Pb-2.0% Si (mass %). Next, the bath temperature and immersion time of the adjusted treatment bath were changed as follows, and a metal Mo plate (length 50 mm, width 10 mm, thickness 1 mm) was immersed in the bath to form a Mo silicide film on the Mo plate, thereby obtaining a Mo alloy material.

[0081] After the Mo silicide film was formed, the immersed Mo plate was taken out of the treatment bath, and after removing any unnecessary bath that had adhered thereto, the Mo alloy material was taken out of the immersion apparatus and recovered.

[0082] <Molten Pb-Si alloy bath> ·Bath temperature: 1000℃ Soaking time: 15 minutes, 30 minutes, 60 minutes

[0083] Diffraction peaks were obtained for each of the Mo alloy materials by X-ray diffraction (XRD). Specifically, XRD measurements were performed on the surface of each of the Mo alloy materials. The XRD measurements were performed using CuKα as a radiation source, with a 2θ range of 10° to 90° at a measurement interval of 0.02° and a measurement speed of 5° / min. The results are shown in Figure 14.

[0084] As shown in FIG. 14, it was found that a Mo silicide film was formed on the surface layer of the Mo alloy material produced by applying the present invention.

[0085] Example 5 Next, in the same manner as in Example 1, using the immersion apparatus shown in FIG. 1, Sn and Si were placed in a crucible (made of Al2O3) under an Ar gas atmosphere and heated with a heater to prepare a treatment bath (molten Sn—Si alloy bath) with a composition of 98.8% Sn-1.2% Si (mass %). Next, the bath temperature and immersion time of the adjusted treatment bath were changed as follows, and a metal W plate (length 50 mm, width 10 mm, thickness 1 mm) was immersed to form a W silicide film on the W plate. W An alloy material was obtained.

[0086] After the W silicide film was formed, the immersed W plate was taken out of the treatment bath, and after removing any unnecessary bath adhering thereto, the W alloy material was taken out of the immersion device and recovered.

[0087] <Molten Sn-Si alloy bath> ·Bath temperature: 1000℃ Soaking time: 15 minutes, 30 minutes, 60 minutes

[0088] Of the W alloy materials obtained, the W alloy material immersed for 60 minutes was subjected to SEM observation and element distribution analysis (element mapping) of the surface layer (including the W silicide film). The results are shown in Figures 15 and 16. Furthermore, energy dispersive X-ray analysis (EDS analysis) was carried out on each of region 1 and region 2 of the SEM image in Figure 15 to investigate the composition of each region. The results are shown in Table 8.

[0089] In addition, each obtained W The diffraction peaks of the alloy material were obtained by X-ray diffraction (XRD). W XRD measurements were performed on the surface of the alloy material. The XRD measurements were performed using CuKα as a radiation source, with a 2θ range of 10° to 90°, a measurement pitch of 0.02°, and a measurement speed of 5° / min. The results are shown in Figure 17.

[0090] As shown in Figures 15 to 17 and Table 8, it was found that a W silicide film was formed on the surface layer of the W alloy material produced by applying the present invention. As shown in Figure 17, the presence of W5Si3 was confirmed by XRD measurement of the surface of each obtained W alloy material. However, as shown in Table 8, the W5Si3 was not detected in the EDS analysis of region 1. This is thought to be because the thickness of the W5Si3 layer formed on the surface layer of the W alloy material was very small. However, as mentioned above, the formation of W5Si3 on the surface layer of the W alloy material in Example 5 was confirmed by XRD measurement (Figure 17).

[0091] [Table 8]

[0092] Example 6 Next, in the same manner as in Example 1, using the immersion apparatus shown in Figure 1, Sn and Si were placed in a crucible (made of Al2O3) under an Ar gas atmosphere and heated with a heater to prepare a treatment bath (molten Sn-Si alloy bath) with a composition of 96.8% Sn-1.2% Si-1% Ag-1% Au (mass %). Next, a metal Mo plate (length 100 mm, width 10 mm, thickness 30 μm) was immersed in the adjusted treatment bath with varying bath temperature and immersion time as shown below, and the entire metal Mo plate was modified to Mo silicide.

[0093] The Mo silicide thus obtained was immersed in the treatment bath, and the treatment bath was cooled and solidified. The Mo silicide was then lifted up together with the solidified treatment bath and removed from the immersion device for recovery. Because the Mo silicide thus obtained was thin, it was cut with the solidified treatment bath still attached to expose the cross section through the plate thickness, and this was used for SEM observation, etc., which will be described later.

[0094] <Molten Sn-Si alloy bath> ·Bath temperature: 1000℃ Soaking time: 4 hours (240 minutes)

[0095] The obtained Mo silicide was subjected to SEM observation of the thickness cross section and element distribution analysis (element mapping), the results of which are shown in FIGS. Furthermore, energy dispersive X-ray analysis (EDS analysis) was carried out on each of region 1 and region 2 of the SEM image in Figure 18 to investigate the composition of each region. The results are shown in Table 9.

[0096] As shown in FIGS. 18 and 19 and Table 9, it was found that when the present invention was applied to manufacture the Mo metal plate, the entire plate could be converted to Mo silicide.

[0097] [Table 9] [Industrial Applicability]

[0098] The metal silicide of the present invention has excellent resistance to high-temperature oxidation and can therefore be suitably used for heating elements, electrical resistors, and the like.

Claims

1. A metal silicide containing elements M and Si as main components, In mass%, Element X: contains 0.001 to 10%; the element X is at least one element selected from the group consisting of Sn, Bi, and Pb; The element M is Mo or W. A metal silicide characterized by:

2. 2. The metal silicide according to claim 1, wherein the element X is Sn.

3. 2. The method for producing a metal silicide according to claim 1, an immersion step of immersing a Mo-based alloy material or a W-based alloy material in a treatment bath containing Si and the element X; The bath temperature of the treatment bath is 200 to 1500°C, The composition of the treatment bath contains 0.001 to 99.99 mass% of Si, and the remainder is the element X.

2. A method for producing a metal silicide comprising the steps of:

4. 4. The method for producing a metal silicide according to claim 3, wherein the element X is Sn.

5. 5. The method for producing a metal silicide according to claim 3, further comprising a preforming step of forming the Mo-based alloy material or the W-based alloy material before the immersion step.

6. A base material and a film made of a metal silicide containing element M formed on the surface of the base material; Equipped with The metal silicide is Contains, by mass%, element X: 0.001 to 10%; the element X is at least one element selected from the group consisting of Sn, Bi, and Pb; the element M is Mo or W, The base material is a Mo-based alloy or a W-based alloy. An alloy material characterized by:

7. 7. The alloy material according to claim 6, wherein the element X is Sn.

8. The method for producing an alloy material according to claim 6, an immersion step of immersing the base material in a treatment bath containing Si and the element X, The bath temperature of the treatment bath is 200 to 1500°C, The composition of the treatment bath contains 0.001 to 99.99 mass% of Si, and the remainder is the element X. A method for manufacturing an alloy material characterized by the above.

9. 9. The method for producing an alloy material according to claim 8, wherein the element X is Sn.

10. The method for producing an alloy material according to claim 8 or 9, further comprising a pre-forming step of forming the base material before the immersion step.

11. A heating element comprising the metal silicide according to claim 1 or 2.

12. An electrical resistor comprising the metal silicide according to claim 1 or 2.

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