Ceramic continuous fiber having metal element and ceramic

Abstract

The present application relates to a ceramic continuous fiber having a metal element and a ceramic matrix composite using the same. The purpose of the present invention is to provide: a continuous ceramic fiber having a metal element, which is suitable for producing a CMC having high heat resistance; and a CMC using the continuous ceramic fiber. The ceramic continuous fiber is characterized in that the ceramic continuous fiber has a metal element, and the metal element has a mass concentration of 10 ppm or more and 1000 ppm or less.

Description

[0001] This application is a divisional application of Chinese Invention Patent Application No. 202180066130.3 (PCT application number PCT / JP2021 / 035351), filed on September 27, 2021, entitled "Continuous Ceramic Fibers Containing Metallic Elements and Ceramic Matrix Composites Using the Same". Technical Field

[0002] This invention relates to continuous ceramic fibers containing metallic elements and ceramic matrix composites using the same. Background Technology

[0003] Ceramic matrix composites (hereinafter referred to as "CMCs"), which combine continuous ceramic fibers with a ceramic matrix, possess damage resistance (damage tolerance) that is not found in ordinary ceramics. Therefore, research is underway on CMCs as alternative materials to heat-resistant metals such as Ni-based alloys.

[0004] It is known that oxide-based CMCs, especially those formed using alumina and mullite oxides, exhibit high chemical stability against environmental substances such as oxygen, water vapor, Ca, Mg, Na, and Si. Furthermore, it is particularly anticipated that CMCs obtained by forming alumina and mullite oxides into continuous ceramic fibers and using these continuous ceramic fibers can be used as components for aerospace jet engines (e.g., Non-Patent Literature 1).

[0005] The limiting operating temperature of oxide-based CMCs is below 1100℃, which is lower than that of non-oxide-based CMCs formed from silicon carbide (limiting operating temperature: ~1500℃). One reason for this is that oxide-based fibers have lower heat resistance than silicon carbide fibers.

[0006] The heat resistance temperature of CMC, such as the extreme service temperature, depends on the heat resistance of the fiber, so efforts have been made to improve the heat resistance of the fiber (e.g., non-patent literature 2 to 4).

[0007] Existing technical documents Non-patent literature Non-patent literature 1: J. AerospaceLab, Issue 3, (2011) 1-12. Non-patent literature 2: J.Am.Ceram.Soc.99, Issue 99, (2016) 1709-1716. Non-patent literature 3: J. Composites: Part A, Issue 32, (2001) 1143-1153. Non-patent literature 4: J. RareEareth, Issue 2, (2012) 175. Summary of the Invention

[0008] The problem that the invention aims to solve In Non-Patent Literature 3, zirconium oxide and yttrium oxide were added during the manufacturing process of alumina fibers to inhibit particle growth and improve creep properties. However, such alumina fibers do not possess the high heat resistance and creep properties of commercially available mullite fibers (Nextel 720). In Non-Patent Literature 4, lanthanum oxide was mixed into the mullite precursor, which hindered the growth of thermal mullite particles in the mullite fibers. The resulting mullite fibers had a heat resistance temperature of approximately 1000°C.

[0009] A common method for producing continuous ceramic fibers includes mixing multiple precursor solutions containing the elements constituting the fibers, adjusting their viscosity, spinning, and firing. In Non-Patent Literature 3 and 4, trace additives are added to the precursor solutions containing the fiber-forming elements. However, it is difficult to uniformly disperse the trace additives in the precursor solutions, leading to aggregation. Therefore, the additives fail to exert their effect. Furthermore, manufacturing fibers containing additives requires cumbersome processes. On the other hand, a common method for adding elements to ceramic materials is ion implantation, which involves implanting ionized atoms or molecules into the material. However, ion implantation requires large-scale equipment. Moreover, in ion implantation, it is difficult to uniformly add elements to continuous ceramic fibers having a cylindrical shape.

[0010] The purpose of this invention is to provide a ceramic continuous fiber with high strength, high heat resistance and containing metal elements suitable for manufacturing CMC, and CMC using the same.

[0011] Methods for solving problems The inventors of this application conducted in-depth research to solve the aforementioned problems. As a result, they discovered that continuous ceramic fibers containing a small amount of a specific metal element can solve these problems. Thus, this invention was completed.

[0012] That is, the present invention as described in the claims. Furthermore, the essence of this disclosure is the ceramic continuous fiber uniformly containing a metal element and the ceramic matrix composite (CMC) using the same, particularly the ceramic continuous fiber and the CMC using the same, and methods for manufacturing them, as shown below.

[0013] [1] A ceramic continuous fiber, characterized in that it contains a metal element having a mass concentration of more than 10 ppm and less than 1000 ppm.

[0014] [2] As described in [1] above, the ceramic continuous fiber, wherein the aforementioned metal element is a metal element other than iron and aluminum.

[0015] [3] The ceramic continuous fiber as described in [1] or [2] above, wherein the aforementioned metallic element is selected from one or more of the group consisting of sodium, potassium, magnesium, calcium, strontium, barium, lanthanum, cerium, praseodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, yttrium, zirconium, neodymium, titanium, scandium, vanadium, chromium, manganese, cobalt, nickel and copper.

[0016] [4] The ceramic continuous fiber as described in any one of [1] to [3] above, wherein the aforementioned metal element is one or more selected from the group consisting of lanthanum, ytterbium, lutetium, magnesium, cerium, zirconium, neodymium, titanium, calcium, yttrium and strontium.

[0017] [5] The ceramic continuous fiber as described in any one of [1] to [4] above, wherein the aforementioned metal element is contained at the grain boundaries of the ceramic constituting the ceramic continuous fiber.

[0018] [6] The ceramic continuous fiber as described in any one of [1] to [5] above, wherein the aforementioned metal element is in at least one of the states of grain boundary diffusion and substitution solid solution.

[0019] [7] The ceramic continuous fiber as described in any one of [1] to [6] above, wherein the aforementioned ceramic continuous fiber is a continuous fiber containing at least alumina.

[0020] [8] The ceramic continuous fiber as described in any one of [1] to [7] above, wherein the growth rate of the microcrystals after heat treatment under atmospheric conditions, 1300°C and 100 hours, calculated by the following formula (1), is less than 160%.

[0021] G = {(d b -d a ) / d a}×100 ···(1) G represents the growth rate of microcrystals (%), d a The crystallite diameter (nm) of the material constituting the ceramic continuous fiber before heat treatment, and d b The crystallite diameter (nm) of the material constituting the fiber in the heat-treated ceramic continuous fiber.

[0022] [9] The ceramic continuous fiber as described in any one of [1] to [8] above, characterized in that the aforementioned ceramic continuous fiber is alumina continuous fiber or mullite continuous fiber.

[0023]

[10] A ceramic matrix composite material, characterized in that it uses any one of the above [1] to [9] ceramic continuous fibers.

[0024]

[11] The ceramic matrix composite material as described in

[10] above, wherein the ceramic matrix constituting the aforementioned ceramic matrix composite material is selected from at least one of the group consisting of alumina, mullite, zirconium oxide and silicon dioxide.

[0025]

[12] The ceramic matrix composite material as described in

[10] or

[11] above, wherein the difference in volumetric tensile strength before and after heat treatment at atmospheric temperature, 1300°C and 100 hours is less than 100 MPa.

[0026]

[13] The method for manufacturing ceramic continuous fibers as described in any one of [1] to [9] above is characterized by comprising the following steps: an impregnation step of immersing the ceramic continuous fibers in a solution containing a metal acetylacetone complex; and a heat treatment step of performing heat treatment at a temperature of 950°C or higher and 1300°C or lower.

[0027]

[14] The method for manufacturing ceramic continuous fibers as described in

[13] above, wherein the aforementioned metal acetylacetone complex is an acetylacetone complex containing one or more of the following: lanthanum, ytterbium, lutetium, magnesium, zirconium, cerium, yttrium, titanium, sodium, potassium, calcium, scandium, vanadium, chromium, manganese, cobalt, nickel, copper, zinc, gallium and strontium.

[0028]

[15] A method for manufacturing ceramic matrix composite material, characterized in that the ceramic continuous fiber described in any one of [1] to [9] is composited with a ceramic matrix.

[0029] Invention Effects The present invention can provide ceramic continuous fibers with high strength, high heat resistance and containing metal elements suitable for manufacturing CMC, and CMC using the same. Attached Figure Description

[0030] [ Figure 1 ] Figure 1 (a) is a TEM image of mullite continuous fibers coated with lanthanum oxide in Example A1. Figure 1 (b) to (e) respectively show the results obtained using EDS Figure 1 (a) Aluminum in mullite continuous fibers coated with lanthanum oxide Figure 1 (b) of, silicon ( Figure 1 (c) ), Lanthanum ( Figure 1 (d) and oxygen ( Figure 1 The image of the distribution of (e)).

[0031] [ Figure 2 ] Figure 2 (a) is a TEM image of lanthanum-containing mullite continuous fibers of Example A1. Figure 2 (b) to (d) respectively show the results obtained using EDS Figure 2(a) Aluminum in lanthanum-containing mullite continuous fibers ( Figure 2 (b) of, silicon ( Figure 2 (c) ), oxygen ( Figure 2 (d) and lanthanum ( Figure 2 The image of the distribution of (e)).

[0032] [ Figure 3 ] Figure 3 STEM image of the cross-section of ytterbium-containing mullite continuous fiber in Example A8 ( Figure 3 (a) and Figure 3 STEM-EDS extraction spectrum in the region enclosed by the square in (a) Figure 3 (b)

[0033] [ Figure 4 ] Figure 4 STEM image of a cross-section of a calcium-containing alumina continuous fiber from Example A14 ( Figure 4 (a) and Figure 4 The STEM-EDS extraction spectrum of the cross-shaped region in (a) Figure 4 (b)

[0034] [ Figure 5 ] Figure 5 STEM image of the cross-section of zirconium-containing alumina continuous fiber in Example A16 ( Figure 5 (a) and Figure 5 The STEM-EDS extraction spectrum of the cross-shaped region in (a) Figure 5 (b)

[0035] [ Figure 6 ] Figure 6 STEM image of the cross-section of a continuous alumina fiber coated with zirconium oxide in Comparative Example A4 ( Figure 6 (a) and Figure 6 The STEM-EDS extraction spectrum of the cross-shaped region in (a) Figure 6 (b) Detailed Implementation

[0036] Hereinafter, an example of an embodiment of the present invention will be shown in detail. The definitions of terms in this specification are as follows. It should be noted that in this specification, "~" includes both the lower and upper ends, referring to the value above the lower end and below the upper end.

[0037] In this invention, "continuous fiber" refers to long-length filamentous fibers and filamentous long-length fibers that can be woven using a textile machine, especially fibers other than short fibers. "Ceramic fiber" refers to polycrystalline ceramics produced through spinning, as well as filamentous polycrystalline ceramics. Furthermore, ceramic fibers can be classified as "short ceramic fibers" and "continuous ceramic fibers" based on their fiber length. Short ceramic fibers refer to ceramic fibers with a fiber length of less than 500 μm. On the other hand, "continuous ceramic fiber" refers to continuous fibers made of ceramic, especially ceramic fibers other than short ceramic fibers (ceramic fibers with a fiber length of 500 μm or more). Additionally, a ceramic fiber can be a single, independent fiber or a bundle of two or more fibers (hereinafter also referred to as a "fiber bundle").

[0038] The term "ceramic continuous fiber characterized by containing a metallic element" refers to a continuous fiber with a structure in which metallic elements are contained within the ceramic fiber's internal structure through grain boundary diffusion, substitutional solid solution, or invasive solid solution. In particular, it refers to a ceramic continuous fiber in which metallic elements of a different type than the metallic elements constituting the polycrystalline ceramic are contained in the intergranular spaces (grain boundaries) of the polycrystalline ceramic constituting the ceramic continuous fiber. Furthermore, in this invention, "ceramic continuous fiber characterized by containing a metallic element" can be used interchangeably with "metal-containing ceramic continuous fiber." The term "ceramic fiber cloth" refers to a fabric of ceramic fibers, especially a fabric of ceramic continuous fibers.

[0039] This invention relates to continuous ceramic fibers, characterized in that the continuous ceramic fibers contain a metal element, wherein the metal element has a mass concentration of 10 ppm to 1000 ppm (hereinafter also referred to as "the continuous ceramic fiber of this invention" or "the metal-containing continuous ceramic fiber of this invention"). Preferably, the continuous ceramic fiber of this invention is a continuous ceramic fiber containing a metal element, wherein the mass concentration of the metal element is 10 ppm to 1000 ppm. More preferably, this invention is a continuous ceramic fiber containing a metal, characterized in that it is formed from continuous ceramic fibers containing a metal element of 10 ppm to 1000 ppm.

[0040] The ceramic continuous fibers (including cermet continuous fibers) of the present invention are not particularly limited as long as they are ceramic continuous fibers. Examples of ceramic continuous fibers in the present invention include one or more selected from the group consisting of SiC continuous fibers (silicon carbide continuous fibers), alumina continuous fibers, and mullite continuous fibers, preferably continuous fibers containing at least an oxide of aluminum (Al), more preferably continuous fibers containing at least alumina. The ceramic continuous fibers are further preferably at least one of alumina continuous fibers and mullite continuous fibers, and even more preferably alumina continuous fibers or mullite continuous fibers. When high heat resistance is required, the ceramic continuous fibers of the present invention are preferably mullite continuous fibers. On the other hand, when high strength is required, the ceramic continuous fibers are preferably alumina continuous fibers. Alumina continuous fibers are preferably continuous fibers formed from polycrystalline alumina. Mullite continuous fibers are preferably fibers formed from polycrystalline mullite, and more preferably fibers formed from polycrystalline mullite and alumina. In mullite fibers, alumina may be included as a second phase.

[0041] In this invention, the ceramic continuous fiber can be a bundle of ceramic continuous fibers, or a ceramic fiber cloth (fiber cloth) formed from the ceramic continuous fibers of this invention. Alternatively, in this invention, the ceramic continuous fiber can also be a ceramic fiber cloth obtained by weaving a bundle of ceramic continuous fibers.

[0042] The metal-containing ceramic continuous fiber of the present invention is a ceramic continuous fiber containing metal elements, that is, a ceramic continuous fiber containing metal elements in the continuous fiber.

[0043] The metal-containing ceramic continuous fiber of the present invention contains a metal element, preferably at least at the grain boundaries of the ceramic constituting the ceramic continuous fiber. The ceramic continuous fiber is composed of polycrystalline ceramic. By including a metal element of a different type than the metal element constituting the polycrystalline ceramic at the grain boundaries, i.e., between the grains of the polycrystalline ceramic, the heat resistance of the ceramic continuous fiber itself is increased.

[0044] It is sufficient that the metal element is present at least at the grain boundaries of the polycrystalline ceramic, and more preferably, the metal element is in at least one of the states of grain boundary diffusion and substitutional solid solution. Therefore, for example, the metal element may not be included in the form of a coating layer (e.g., an inorganic acid salt coating layer) on the surface of the ceramic continuous fiber. Whether the metal-containing ceramic continuous fiber of the present invention contains the metal element in the form of a coating layer can be confirmed based on TEM or SEM images of its surface. That is, in TEM or SEM images of the cross-section of the ceramic continuous fiber, the coating layer is observed as a metal compound layer of several nm to hundreds of nm on the surface of the ceramic continuous fiber. Therefore, it can be confirmed that the ceramic continuous fiber does not contain a coating layer based on the fact that no metal compound layer is observed on the surface of the ceramic continuous fiber in the cross-sectional SEM image of the metal-containing ceramic continuous fiber of the present invention.

[0045] The metal element contained in the metal-ceramic continuous fibers of the present invention is a different type of metal element from the metal element constituting ceramic fibers, i.e., filamentous polycrystalline ceramics. For example, in alumina fibers and mullite fibers, it is a metal element other than aluminum (Al). In addition, in continuous fibers containing aluminum oxides, it is a metal element other than aluminum, preferably a metal element other than aluminum and iron.

[0046] The metal element contained in the metal-ceramic continuous fiber of the present invention is preferably one or more selected from the group consisting of alkali metals, alkaline earth metals, transition metals, zinc, and gallium, and more preferably at least one selected from alkaline earth metals and transition metals. It should be noted that the metal element in the present invention does not include silicon (Si).

[0047] Alkali metals may include at least one of sodium and potassium. Alkali earth metals may include one or more selected from the group consisting of magnesium, calcium, strontium, and barium, and may further include at least one of magnesium and calcium. Transition metals may include one or more selected from the group consisting of lanthanum, cerium, praseodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, yttrium, zirconium, neodymium, titanium, scandium, vanadium, chromium, manganese, cobalt, nickel, and copper, and may further include one or more selected from the group consisting of lanthanum, cerium, praseodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, yttrium, zirconium, neodymium, titanium, scandium, and yttrium. One or more of the group consisting of vanadium, chromium, manganese, cobalt, nickel and copper, and more specifically, one or more of the group consisting of lanthanum, ytterbium, lutetium, cerium, yttrium, zirconium, neodymium, titanium, scandium, vanadium, chromium, manganese, cobalt, nickel and copper, and more specifically, one or more of the group consisting of lanthanum, cerium, yttrium, zirconium, neodymium, titanium, scandium, vanadium, chromium, manganese, cobalt, nickel and copper.

[0048] In order to easily obtain the desired effect within the range of metal content in the continuous metal-ceramic fibers of the present invention, the metal element is preferably a metal element other than aluminum and iron.

[0049] The metallic element in the continuous metal-ceramic fiber of the present invention is preferably selected from one or more of the group consisting of sodium, potassium, magnesium, calcium, strontium, barium, lanthanum, cerium, praseodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, yttrium, zirconium, neodymium, titanium, scandium, vanadium, chromium, manganese, cobalt, nickel, and copper; more preferably, it is selected from one or more of the group consisting of lanthanum, ytterbium, lutetium, magnesium, cerium, zirconium, neodymium, titanium, calcium, yttrium, and strontium. More preferably, the metal element is selected from one or more of the group consisting of lanthanum, magnesium, cerium, zirconium, neodymium, and titanium; more preferably, it is selected from one or more of the group consisting of lanthanum, magnesium, cerium, zirconium, neodymium, titanium, calcium, yttrium, and strontium; more preferably, it is selected from one or more of the group consisting of lanthanum, magnesium, cerium, zirconium, neodymium, and titanium; and most preferably, it is selected from one or more of the group consisting of lanthanum (La), magnesium (Mg), and zirconium (Zr). These metal elements particularly readily improve the heat resistance of continuous fibers formed from aluminum oxides. When the ceramic continuous fiber is alumina continuous fiber, as a metal element, it is more preferable to include one or more of the group consisting of lanthanum, magnesium, calcium, neodymium, zirconium, strontium, and yttrium; more preferably, it includes at least one of magnesium and zirconium. In addition, when the ceramic continuous fiber is mullite continuous fiber, as a metal element, it is more preferable to include one or more of the group consisting of lanthanum, magnesium, cerium, zirconium, strontium, and yttrium; more preferably, it includes at least one of lanthanum and magnesium.

[0050] The metal-containing ceramic continuous fiber of the present invention is characterized by having a metal element in the fiber (i.e., in the ceramic continuous fiber) with a mass concentration of 10 ppm to 1000 ppm, that is, the content of the metal element, expressed as a mass concentration, is 10 ppm to 1000 ppm to 1000 ppm. The mass concentration of the metal element in the metal-containing ceramic continuous fiber (hereinafter also referred to as "metal content," and in the case of lanthanum, etc., it is also referred to as "lanthanum content," etc.) is the content of each metal element in the ceramic continuous fiber. Preferably, the metal-containing ceramic continuous fiber of the present invention is characterized by the content of each metal element being 10 ppm to 1000 ppm to 1000 ppm. The metal content of the metal-containing ceramic continuous fiber is preferably 30 ppm to 900 ppm to 1000 ppm, more preferably 50 ppm to 800 ppm to 1000 ppm to 1000 ppm. If the metal content is less than 10 ppm, the effect of improving heat resistance is not obtained; only the same level of heat resistance as that of ceramic continuous fibers without metal elements can be obtained. If the metal content is greater than 1000 ppm, the structure of the ceramic continuous fiber itself changes significantly (i.e., the strength of the ceramic continuous fiber itself, which becomes the substrate, decreases). As a result, the strength of the metal-ceramic continuous fiber itself deteriorates (reduces).

[0051] In addition, examples of metal content include: lanthanum content of 50 ppm or more or 70 ppm or more, and 900 ppm or less or 800 ppm or less; magnesium content of 10 ppm or more or 20 ppm or more, and 900 ppm or less or 800 ppm or less; or zirconium content of 10 ppm or more or 20 ppm or more, and 900 ppm or less or 800 ppm or less.

[0052] More preferably, the metal-ceramic continuous fiber of the present invention is a metal-ceramic continuous fiber containing one or more metallic elements selected from the group consisting of sodium, potassium, magnesium, calcium, strontium, barium, lanthanum, cerium, praseodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, yttrium, zirconium, neodymium, titanium, scandium, vanadium, chromium, manganese, cobalt, nickel and copper, and satisfying at least one of (a) and (b) below.

[0053] (a) Calcium content greater than 20 ppm and less than 1000 ppm, magnesium content greater than 25 ppm and less than 1000 ppm, or zirconium content greater than 15 ppm and less than 1000 ppm. (b) The content of any of the aforementioned metallic elements, excluding calcium, magnesium and zirconium, is between 10 ppm and 1000 ppm.

[0054] Further preferably, the metal-ceramic continuous fiber of the present invention is a metal-ceramic continuous fiber containing one or more metallic elements selected from the group consisting of magnesium, calcium, strontium, lanthanum, ytterbium, lutetium, cerium, yttrium, zirconium and neodymium, and satisfying at least one of (a) and (b) below.

[0055] (a) Calcium content greater than 20 ppm and less than 1000 ppm, magnesium content greater than 25 ppm and less than 1000 ppm, or zirconium content greater than 15 ppm and less than 1000 ppm. (b) The content of any of the aforementioned metallic elements, excluding calcium, magnesium and zirconium, is between 10 ppm and 1000 ppm.

[0056] Furthermore, regarding the metal-ceramic continuous fiber of the present invention, it is preferable that the total content of the metal elements composed of sodium, potassium, magnesium, calcium, strontium, barium, lanthanum, cerium, praseodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, yttrium, zirconium, neodymium, titanium, scandium, vanadium, chromium, manganese, cobalt, nickel, and copper, preferably the total content of the metal elements composed of magnesium, calcium, strontium, lanthanum, ytterbium, lutetium, cerium, yttrium, zirconium, and neodymium, is 10 ppm or more or 30 ppm or more, and is 1000 ppm or less, 200 ppm or less, or 120 ppm or less.

[0057] Further preferably, the metal-ceramic continuous fiber of the present invention is a metal-ceramic continuous fiber containing one or more metallic elements selected from the group consisting of magnesium, calcium, strontium, lanthanum, ytterbium, lutetium, cerium, yttrium, zirconium and neodymium, and satisfying at least one of (a) and (b) below.

[0058] (a) Calcium content greater than 20 ppm and less than 1000 ppm, magnesium content greater than 25 ppm and less than 1000 ppm, or zirconium content greater than 15 ppm and less than 1000 ppm. (b) The content of any of the aforementioned metallic elements, excluding calcium, magnesium and zirconium, is between 10 ppm and 1000 ppm.

[0059] Metal content can be determined using ICP-based spectral analysis. Mass concentration is the mass of a metallic element contained in a unit mass of continuous ceramic fiber. For example, if 1g of alumina fiber contains 100μg of lanthanum (La), the mass concentration (ppm) is 100ppm, which can be calculated using the following formula.

[0060] Metal content [ppm] = Mass of metal element [g] / Mass of continuous ceramic fiber [g] = Mass of lanthanum (La) / Mass of alumina fiber = 100 [μg] / 1 [g] = 100 [ppm] In this invention, ICP emission spectrophotometry can be performed using a conventional ICP emission analysis apparatus (e.g., a Vista-PRO axial specification manufactured by Seiko Instruments). The following conditions can be cited as measurement conditions for ICP emission spectrophotometry.

[0061] Frequency: 40MHz Output power: 1.0kW Detector: CCD detector Sample introduction: pneumatic atomizer For the samples used in ICP luminescence spectrophotometry, continuous ceramic fibers obtained by pressurized sulfuric acid decomposition at 230°C for 144 hours are acceptable.

[0062] It should be noted that the ceramic continuous fibers (hereinafter also referred to as "raw material fibers") used as raw materials for the metal-ceramic continuous fibers of the present invention sometimes contain unavoidable impurities. In this case, the metal content is the mass concentration of the metal element containing the unavoidable impurities of the raw material fibers.

[0063] On the other hand, the mass concentration of metal elements free from unavoidable impurities contained in the raw material fibers (hereinafter also referred to as "doped metal content") is the content of metal elements obtained by removing metal elements from the raw material fibers from the metal elements contained in the metal-containing ceramic continuous fibers of the present invention; the so-called mass concentration of doped metal elements. Doped metal elements are metal elements contained in the ceramic continuous fibers after spinning. In addition, the doped metal content can be calculated by the following formula.

[0064] Mass concentration (doped metal content) [ppm] = Metal element concentration [ppm] in the metal-ceramic continuous fiber of this invention - Metal element concentration [ppm] in the raw material fiber In the above formula, "the concentration of metal elements contained in the metal-ceramic continuous fiber of the present invention" refers to the concentration of metal elements obtained by ICP-based spectrophotometric analysis of the metal-ceramic continuous fiber, preferably one that has not undergone heat treatment at 1000°C or higher, and is the aforementioned metal content. Furthermore, "the concentration of metal elements contained in the raw material fiber" refers to the concentration of metal elements obtained by ICP-based spectrophotometric analysis of the raw material fiber supplied as the raw material for the metal-ceramic continuous fiber of the present invention. The metal elements contained in the raw material fiber and their content vary greatly depending on the type of raw material fiber, manufacturing batch, etc. For example, in the case of mullite continuous fiber (trade name: Nextel 720, manufactured by 3M) and alumina continuous fiber (trade name: Nextel 610, manufactured by 3M), iron is a major unavoidable impurity.

[0065] The doped metal content of the continuous metal-ceramic fibers of the present invention is preferably 1 ppm or more and 1000 ppm or less, more preferably 3 ppm or more and 1000 ppm or less, and particularly preferably 5 ppm or more and 1000 ppm or less. Examples include: the lanthanum content (hereinafter, the content of the doped metal when the doped metal element is lanthanum, etc., is also referred to as "lanthanum doping content", etc.), neodymium doping content, lutetium doping content, strontium doping content, and yttrium doping content are each 10 ppm or more or 50 ppm or more, and are 300 ppm or less or 150 ppm or less; the magnesium doping content is 5 ppm or more or 10 ppm or more, and are 50 ppm or less or 25 ppm or less; the calcium doping content is 5 ppm or more or 10 ppm or more, and are 50 ppm or less or 30 ppm or less; the ytterbium doping content and zirconium doping content are each 10 ppm or more or 50 ppm or more, and are 250 ppm or less, 200 ppm or less, or 100 ppm or less, respectively.

[0066] Regarding the ceramic continuous fibers (including cermet continuous fibers) of the present invention, the crystallite diameter of the constituent material of the fiber, i.e., the polycrystalline ceramic, depends on the type of ceramic and can have any crystallite diameter. For example, the crystallite diameter of alumina in alumina continuous fibers can be 60 nm or more, or 70 nm or more, and 100 nm or less, or 90 nm or less. Furthermore, the crystallite diameter of alumina in mullite fibers containing alumina can be 20 nm or more, or 30 nm or more, and 60 nm or less, or 50 nm or less.

[0067] The crystallite diameter can be determined using the XRD pattern of the ceramic continuous fiber, according to the following Scherrer formula.

[0068] D=K×λ / ((β-B)×cosθ) In the above formula, D is the average crystallite diameter (nm), K is the Scherrer constant (1.0), λ is the wavelength of CuKα (0.15418nm), β is the integral width (rad), B is the device constant (rad), and θ is the measured diffraction angle. The device constant is a constant used to correct for the spread of X-rays originating from the device and can be determined using silicon as a standard sample using methods known to those skilled in the art. Additionally, the integral width can be determined using Integral Analysis for Windows (Version 6.0) manufactured by Rigaku Corporation, and the analysis function can be the segmented voigt function. When calculating the crystallite diameter of alumina, the diffraction angle can be the diffraction angle of the mullite continuous fiber containing alumina with a peak at approximately 2θ = 68° (2θ = 68 ± 0.2°) corresponding to the (300) plane of the hexagonal crystal of alumina, and the diffraction angle of the mullite continuous fiber with a peak at approximately 2θ = 35° (2θ = 35 ± 0.2°) corresponding to the (104) plane of the hexagonal crystal of alumina. When calculating the crystallite diameter of mullite, the diffraction angle can be the diffraction angle of the peak at approximately 2θ = 33.1° (2θ = 33.1 ± 0.2°) of the mullite continuous fiber. Regarding the device constant, for example, 0.003002 (rad) can be cited in the case of mullite continuous fiber, and 0.002723 (rad) can be cited in the case of alumina continuous fiber.

[0069] XRD patterns can be obtained using a conventional powder X-ray diffraction apparatus (e.g., Ultima III, manufactured by Rigaku Corporation) by XRD determination under the following conditions.

[0070] X-ray source: CuKα rays (λ=0.15418nm) Measurement mode: Step scan Scanning conditions: 0.04° per second Diverging slit: 2 / 3deg Scattering slit: 2 / 3deg Light-receiving slit: 0.3mm Measurement time: 2.0 seconds Measurement range: 2θ = 20°~80° By incorporating metallic elements into the metal-ceramic continuous fibers of the present invention, the growth of microcrystals in the fiber-forming material (polycrystalline ceramic) caused by prolonged heat treatment at high temperatures can be suppressed. As a result, the metal-ceramic continuous fibers of the present invention contain a fine microstructure (small crystallite diameter) even after prolonged heat treatment, exhibiting high heat resistance.

[0071] There is a tendency for the crystallites to grow larger with increasing heat load. Furthermore, the degree of crystallization relative to heat load varies depending on the type of ceramic constituting the continuous ceramic fiber. For the metal-containing ceramic continuous fiber of the present invention, an example is a crystallization growth rate (hereinafter also referred to as "crystal growth rate") of 160% or less after heat treatment. Since heat treatment causes the crystallites to grow larger, an example is a crystallization growth rate of 0% or more, or greater than 0%.

[0072] The growth rate of microcrystals after heat treatment can be calculated using the following formula (1).

[0073] G = {(d b -d a ) / d a}×100 ···(1) G represents the growth rate of microcrystals (%), d a The crystallite diameter (nm) of the material constituting the ceramic continuous fiber before heat treatment, and d b The crystallite diameter (nm) of the material constituting the fiber in the heat-treated ceramic continuous fiber.

[0074] The following conditions can be cited as heat treatment conditions for continuous ceramic fibers in the determination of microcrystal growth rate.

[0075] Heat treatment atmosphere: Atmospheric atmosphere Heat treatment temperature: 1300℃ Heat treatment time: 100 hours When the ceramic continuous fiber is alumina continuous fiber, the microcrystal growth rate of the alumina microcrystals is preferably 160% or less, more preferably 120% or less or 100% or less, and even more preferably 0% or more, 20% or more, 40% or more or 60% or more.

[0076] When the ceramic continuous fiber is mullite continuous fiber containing alumina, the crystallite growth rate of the alumina microcrystals is preferably 75% or less, 60% or less, 50% or less, or 35% or less, and more preferably 0% or more, 5% or more, or 15% or more. Furthermore, when the ceramic continuous fiber is mullite continuous fiber, the crystallite growth rate after heat treatment at atmospheric atmosphere (i.e., in the atmosphere), 1200°C, and 100 hours is preferably 17% or less, more preferably 3% or more and 17% or less.

[0077] The heat resistance of continuous ceramic fibers can be evaluated by measuring the tensile strength of a single fiber. Specifically, the tensile strength (hereinafter also referred to as "single fiber tensile strength") of the heat-treated continuous ceramic fibers can be determined using a method based on JISR 1657, Method B. The conditions for determining the single fiber tensile strength are shown below.

[0078] Gauge length: 25mm Test speed: 0.5 mm / min In addition, the following conditions can be cited as heat treatment conditions for ceramic continuous fibers that provide tensile strength for single fibers.

[0079] Heat treatment atmosphere: Atmospheric atmosphere Heat treatment temperature: 1300℃ Heat treatment time: 100 hours Regarding the ceramic continuous fiber of the present invention, the tensile strength of the single fiber after the above-described heat treatment is preferably greater than 1.0 GPa, 1.1 GPa or more, or 1.2 GPa or more. Therefore, it is easy to obtain CMC with high strength even after exposure to high temperatures. The tensile strength of the single fiber after the above-described heat treatment can be exemplified as 1.7 GPa or less or 1.5 GPa or less.

[0080] Regarding the ceramic continuous fibers of the present invention, examples can be given where the difference in tensile strength of a single fiber before and after heat treatment is less than 0.5 GPa or less than 0.4 GPa, and more than 0 GPa or more than 0.1 GPa. It should be noted that the difference in tensile strength of a single fiber before and after heat treatment varies slightly depending on the type of ceramic continuous fiber. For example, compared to alumina continuous fibers, mullite continuous fibers tend to have a smaller difference in tensile strength of a single fiber before and after heat treatment.

[0081] The ceramic continuous fibers containing metallic elements of the present invention are suitable for use as CMCs. Compared with conventional ceramic continuous fibers, the ceramic continuous fibers containing metallic elements of the present invention have high heat resistance, and therefore, when used as CMCs compounded with ceramic matrices, the CMCs exhibit high heat resistance.

[0082] As a preferred metal-ceramic continuous fiber of the present invention, the following metal-ceramic continuous fiber can be cited as an example, which contains one or more metallic elements selected from the group consisting of lanthanum, ytterbium, lutetium, magnesium, cerium, strontium, yttrium, neodymium, titanium, zirconium, calcium, scandium, vanadium, chromium, manganese, cobalt, nickel and copper, and the content of each metallic element is 10 ppm or more, 30 ppm or more, or 50 ppm or more, and is 1000 ppm or less, 500 ppm or less, 250 ppm or less, or 120 ppm or less.

[0083] Furthermore, as a preferred metal-ceramic continuous fiber of the present invention, the following metal-ceramic continuous fiber can be cited, which contains one or more metal elements selected from the group consisting of lanthanum, ytterbium, lutetium, magnesium, cerium, strontium, yttrium, neodymium, titanium, zirconium, calcium, scandium, vanadium, chromium, manganese, cobalt, nickel and copper as doping metal elements, and the content of each metal element is 10 ppm or more, 30 ppm or more, or 50 ppm or more, and is 1000 ppm or less, 500 ppm or less, 250 ppm or less, or 120 ppm or less.

[0084] Ceramic matrix composites (CMC) One embodiment of the ceramic matrix composite material (hereinafter also referred to as "the CMC of the present invention") is a material formed by combining the above-mentioned continuous ceramic fibers (containing metal-ceramic continuous fibers) with a ceramic matrix. That is, the CMC of this embodiment is a ceramic matrix composite material composed of the above-mentioned continuous metal-ceramic fibers and a ceramic matrix, and more specifically, a ceramic fiber reinforced ceramic formed from a ceramic matrix containing the above-mentioned continuous metal-ceramic fibers.

[0085] The ceramic matrix constituting the CMC of the present invention is at least one of oxide ceramics and non-oxide ceramics, preferably oxide ceramics, more preferably at least one selected from the group consisting of alumina, mullite, zirconium oxide and silicon dioxide, and even more preferably one or more selected from the group consisting of alumina, mullite and silicon dioxide, preferably at least one of alumina and mullite. Furthermore, from the viewpoint of strength, the ceramic matrix is ​​preferably alumina. On the other hand, from the viewpoint of heat resistance, the ceramic matrix is ​​preferably mullite. Moreover, the ceramic matrix and the continuous ceramic fibers are preferably made of the same material. For example, the CMC of this embodiment is preferably a CMC formed of continuous alumina fibers and an alumina matrix, or a CMC formed of continuous mullite fibers and a mullite matrix, or a CMC formed of continuous silicon carbide fibers and a silicon carbide matrix. On the other hand, the main components constituting the ceramic matrix and the continuous ceramic fibers in the CMC of this embodiment may also be different.

[0086] The density of CMC in this embodiment varies depending on the type of ceramic matrix, etc., and for example, it can be 2.50 g / cm³. 3 Above or 2.70 g / cm 3 The above, and 3.20 g / cm³ 3 Below or 3.00g / cm 3 the following.

[0087] The fiber volume fraction of the CMC of the present invention can be exemplified as 10% or more or 20% or more, and 45% or less or 40% or less.

[0088] The term "fiber volume fraction" refers to the volume percentage [vol%] of continuous ceramic fibers in CMC. The fiber volume fraction can be calculated using the following formula.

[0089] Fiber volume fraction [%] = (V f / V CMC 100 In the above formula, V f V is the volume of the continuous ceramic fiber. CMC This refers to the volume of the CMC. Additionally, V... f and V CMC They can be obtained from the following formulas.

[0090] V f = m / ρ f V cmc = A×B×t In the above formula, m is the mass [g] of the ceramic continuous fiber, and ρ f Density of ceramic continuous fibers [g / cm³] 3 Additionally, A is the length of the CMC [mm], B is the width of the CMC [mm], and t is the thickness of the CMC [mm].

[0091] The heat resistance of CMC can be evaluated using a tensile test. Specifically, the tensile strength of heat-treated CMC can be determined using a method based on JIS R 1656, and the difference between the tensile strength and the tensile strength can be measured. The following shows the conditions for determining the tensile strength (hereinafter also referred to as "volume tensile strength") of CMC.

[0092] Test speed: 0.5 mm / min The test specimen for the volumetric tensile strength test can be a plate-shaped CMC with a width of 10 mm × a length of 110 mm × a thickness of 2.5 mm. Furthermore, the following conditions can be cited as heat treatment conditions for the CMC used in the volumetric tensile strength test.

[0093] Heat treatment atmosphere: Atmospheric atmosphere Heat treatment temperature: 1300℃ Heat treatment time: 100 hours Regarding the CMC of this embodiment, the volumetric tensile strength after the heat treatment is preferably 70 MPa or more or 100 MPa or more. The volumetric tensile strength after heat treatment varies depending on the type of ceramic continuous fiber constituting the metal-ceramic continuous fiber. For example, in the case of alumina continuous fibers containing metal, the volumetric tensile strength after heat treatment can be 135 MPa or more, and further 150 MPa or more; on the other hand, it can be 280 MPa or less, 250 MPa or less, or 225 MPa or less. Furthermore, in the case of mullite continuous fibers containing metal, especially alumina mullite continuous fibers, the volumetric tensile strength after heat treatment can be 60 MPa or more, and further 70 MPa or more; on the other hand, it can be 200 MPa or less or 160 MPa or less.

[0094] It should be noted that the difference between the volumetric tensile strength before and after heat treatment (volumetric tensile strength before heat treatment - volumetric tensile strength after heat treatment) is preferably small, for example, less than 100 MPa, more preferably less than 80 MPa, and even more preferably less than 50 MPa.

[0095] [Manufacturing method of continuous ceramic fibers containing metallic elements] The following describes the manufacturing method of the ceramic continuous fiber containing metallic elements according to the present invention.

[0096] Regarding the manufacturing method of the metal-ceramic continuous fiber of the present invention, examples include an impregnation step of immersing the ceramic continuous fiber in a solution containing a metal acetylacetone complex and a heat treatment step of performing heat treatment at 950°C to 1300°C. In addition, a preferred manufacturing method is one that includes an impregnation step of immersing the ceramic continuous fiber in a solution containing a metal acetylacetone complex to obtain a precursor and a heat treatment step of performing heat treatment on the precursor at 950°C to 1300°C.

[0097] The ceramic continuous fibers (raw material fibers) supplied for the impregnation process are not particularly limited as long as they are ceramic continuous fibers, and examples include SiC continuous fibers, alumina continuous fibers, mullite continuous fibers, etc., preferably at least one of alumina continuous fibers and mullite continuous fibers, more preferably alumina continuous fibers or mullite continuous fibers. When higher heat resistance is required, the raw material fiber is preferably mullite continuous fibers; on the other hand, when higher strength is required, the raw material fiber is preferably alumina continuous fibers. Alumina continuous fibers are preferably fibers formed from polycrystalline alumina, and mullite continuous fibers are preferably fibers formed from polycrystalline mullite, or fibers formed from polycrystalline mullite and alumina. Alumina may be included as a second phase in the mullite fibers. In this invention, it is preferable to supply ceramic continuous fibers with exposed surface hydroxyl groups for the impregnation process, that is, ceramic continuous fibers supplied for the impregnation process are ceramic continuous fibers with hydroxyl groups on their surface.

[0098] The ceramic continuous fibers used in the manufacturing method of the present invention containing metal-ceramic continuous fibers are preferably ceramic fiber bundles or ceramic fiber cloths. The ceramic fiber cloths may also be commercially available. Examples of commercially available ceramic fiber cloths include SiC fiber ceramic fiber cloths (SiC fiber cloths) such as Hi-Nicalon (manufactured by Nippon Carbon) and Tyranno fiber (manufactured by Ube Industries), alumina fiber ceramic fiber cloths (alumina fiber cloths) such as Nextel 610 (manufactured by 3M), and mullite fiber ceramic fiber cloths (mullite fiber cloths) such as Nextel 720 (manufactured by 3M).

[0099] In the impregnation process, the raw material fibers are impregnated in a solution containing a metal acetylacetone complex (hereinafter also referred to as the "metal AcAc complex"). As a result, the metal AcAc complex is adsorbed onto the surface of the continuous ceramic fibers, yielding continuous ceramic fibers with the metal AcAc complex adsorbed as a precursor.

[0100] Examples of metal AcAc complexes used in impregnation include one or more acetylacetone complexes selected from the group consisting of lanthanum, ytterbium, lutetium, magnesium, zirconium, cerium, yttrium, titanium, sodium, potassium, calcium, scandium, vanadium, chromium, manganese, cobalt, nickel, copper, zinc, gallium, and strontium. Preferably, it includes one or more AcAc complexes selected from the group consisting of lanthanum, magnesium, cerium, yttrium, calcium, and scandium. More preferably, it includes one or more AcAc complexes selected from the group consisting of lanthanum, magnesium, and zirconium. Specific metal AcAc complexes include, for example, lanthanum(III) acetylacetone dihydrate (La(CH3COCHCOCH3)3·2H2O), ytterbium(III) acetylacetone hydrate (Yb(CH3COCHCOCH3)3·nH2O), lutetium(III) acetylacetone hydrate (Lu(CH3COCHCOCH3)3·nH2O), magnesium(II) acetylacetone hydrate (Mg(CH3COCHCOCH3)2·nH2O), and zirconium(IV) acetylacetone (Zr(CH3COC)2·nH2O). (CH3COCHCOCH3)4), Cerium(III) acetylacetonate trihydrate (Ce(CH3COCHCOCH3)3·3H2O), Yttrium(III) acetylacetonate n hydrate (Y(CH3COCHCOCH3)3·nH2O), Titanium(IV) acetylacetonate (Ti(CH3COCHCOCH3)4), Sodium(I) acetylacetonate hydrate (Na(CH3COCHCOCH3)·nH2O), Potassium hemihydrate of acetylacetonate (K(CH3COCHCOCH3)·0.5H2O), acetylacetonate Calcium(II) acetylacetone hydrate (Ca(CH3COCHCOCH3)2·nH2O), scandium(III) acetylacetone hydrate (Sc(CH3COCHCOCH3)3·nH2O), vanadium(III) acetylacetone (V(CH3COCHCOCH3)3), chromium(III) acetylacetone (Cr(CH3COCHCOCH3)3), manganese(III) acetylacetone (Mn(CH3COCHCOCH3)3), cobalt(II) acetylacetone hydrate (Co(CH3COCHCOCH3)3) At least one of the following: nickel(CH3COCHCOCH3)2·nH2O, copper(II)(CH3COCHCOCH3)2, zinc(II)(CH3COCHCOCH3)2·nH2O, gallium(III)(CH3COCHCOCH3)3, and strontium(II)(CH3COCHCOCH3)2·nH2O.The metal acetylacetone compound is preferably selected from at least one of the following groups: lanthanum(III) acetylacetone dihydrate, ytterbium(III) acetylacetone hydrate, lutetium(III) acetylacetone hydrate, magnesium(II) acetylacetone hydrate, zirconium(IV) acetylacetone, cerium(III) acetylacetone trihydrate, yttrium(III)n acetylacetone hydrate, titanium(IV) acetylacetone, calcium(II) acetylacetone hydrate (Ca(CH3COCHCOCH3)2·nH2O), and strontium(II) acetylacetone hydrate, more preferably selected from at least one of the following groups: lanthanum(III) acetylacetone dihydrate, magnesium(II) acetylacetone hydrate, and zirconium(IV) acetylacetone.

[0101] The solvent in the solution containing the metal AcAc complex (hereinafter also referred to as "metal AcAc solution") is any solvent in which the metal AcAc complex does not decompose and can be dissolved, and there is no particular limitation. Preferred solvents include, for example, alcohols such as methanol, ethanol, and propanol, organic solvents such as acetone and benzene, water, and heavy water, preferably at least one of water and alcohols, and more preferably at least one of methanol and ethanol.

[0102] A metal AcAc solution only needs to contain a metal AcAc complex and a solvent, and can be a solution formed by a metal AcAc complex and a solvent.

[0103] Regarding impregnation, any conditions suitable for the chemical adsorption reaction of the metal AcAc complex into the continuous ceramic fibers are acceptable. The impregnation temperature can be below the boiling point of the solvent, preferably room temperature (25±3°C). The impregnation time can be 30 minutes to 24 hours, preferably 1 hour to 5 hours. To facilitate the chemical adsorption reaction, it is preferable to perform impregnation while heating below the boiling point of the solvent.

[0104] In the heat treatment process, the precursor, i.e., the impregnated ceramic continuous fiber (ceramic continuous fiber adsorbed with a metal AcAc complex), is heat-treated at a temperature of 950°C to 1300°C. Through heat treatment, the organic components in the metal AcAc complex are decomposed, and the metal elements undergo uniform thermal diffusion within the ceramic continuous fiber. The heat treatment temperature is 950°C to 1300°C. Thus, during the heat treatment process, a metal oxide film is uniformly formed on the fiber surface, and simultaneously, the film-formed metal elements undergo uniform thermal diffusion between the grains of the polycrystalline ceramic constituting the fiber. If the temperature is below 950°C, the metal elements from the metal AcAc complex do not diffuse easily, and the metal elements tend to remain on the fiber surface. If the temperature is above 1300°C, the ceramic continuous fiber undergoes thermal degradation. The heat treatment temperature is preferably 1000°C to 1300°C, more preferably 1050°C to 1250°C, further preferably 1100°C to 1200°C, and particularly preferably 1100°C to 1175°C. The heat treatment time can be adjusted appropriately according to the size of the ceramic continuous fibers and the firing furnace used, and can be exemplified as more than 1 hour and less than 5 hours. The heat treatment atmosphere is arbitrary, and an oxidizing atmosphere is an example, with an atmospheric atmosphere being preferred.

[0105] It is believed that by heat-treating only the continuous ceramic fiber, that is, by heat-treating the continuous ceramic fiber in a state where the continuous ceramic fiber does not coexist with the ceramic matrix or other materials that are composite with the fiber, the metal elements on the fiber surface will not be dissolved or absorbed into the ceramic matrix, but will diffuse inside the fiber.

[0106] Furthermore, in this invention, as a pretreatment before heat treatment (i.e., before the heat treatment process), the ceramic continuous fibers after the impregnation process may be heat-treated at a temperature of 500°C or higher and lower than 950°C, preferably 700°C or higher and lower than 950°C. The pretreatment time can be appropriately varied depending on the size of the ceramic continuous fibers and the firing furnace used, and can be exemplified as 1 hour or more and 5 hours or less. The heat treatment atmosphere is arbitrary, and an oxidizing atmosphere is an example, with an atmospheric atmosphere being a preferred example.

[0107] The manufacturing method of the present invention can repeat the impregnation process and the heat treatment process more than twice, more than twice but less than ten times, and even more than three times but less than eight times. The metal content can be controlled by the number of times the impregnation process and the heat treatment process are repeated. There is a tendency that the metal content of the ceramic continuous fiber (including metal ceramic continuous fiber) of the present invention increases as the number of repetitions of the process increases. The number of repetitions is preferably more than once and less than ten times. If the number of repetitions exceeds ten times, the strength of the fiber will decrease due to the heat treatment.

[0108] [Manufacturing method of ceramic matrix composites (CMC)] Regarding the manufacturing method of CMC in this embodiment, any method that corresponds to the objective can be used as long as it can produce CMC containing continuous metal-ceramic fibers as described in this embodiment. One embodiment of the manufacturing method for a ceramic matrix composite material can be exemplified by the following manufacturing method, characterized by including a composite process that composites the aforementioned continuous ceramic fibers (containing continuous metal-ceramic fibers) with a ceramic matrix.

[0109] The method of composite formation is arbitrary. As a preferred method, examples include: a method of impregnating ceramic continuous fibers (including metal-ceramic continuous fibers) in a slurry containing a ceramic matrix (hereinafter also referred to as "raw material slurry") and then heat-treating it; a method of impregnating metal-ceramic continuous fibers in the raw material slurry and then impregnating them in a precursor and heat-treating them; further examples include a CMC manufacturing method having the following steps: a molding step, in which the raw material slurry is mixed with the coated ceramic continuous fibers of this embodiment and then molded to obtain a molded body; and a firing step, in which the molded body is fired.

[0110] The raw material slurry is preferably a slurry containing a ceramic matrix and ceramic powder dispersed in a solvent. Examples of ceramic powder include slurries containing at least one selected from the group consisting of alumina, mullite, silica, and zirconium oxide (preferably at least one of alumina and mullite, further at least one of alumina and mullite, and even further alumina).

[0111] The solvent for the raw material slurry can be any solvent that can disperse the ceramic powder, such as water or alcohol, with water being the preferred choice.

[0112] To disperse ceramic powder in a solvent, dispersants, etc., can be used.

[0113] The method of mixing the raw material slurry with the metal-ceramic continuous fiber of this embodiment is arbitrary; for example, the metal-ceramic continuous fiber of this embodiment can be impregnated in the raw material slurry. The impregnation conditions are arbitrary, as long as the metal-ceramic continuous fiber is completely impregnated in the raw material slurry.

[0114] After mixing the raw material slurry with the metal-ceramic continuous fibers of this embodiment, the resulting mixture is molded. Molding can be performed using any method that gives the mixture a certain shape; for example, heating the mixture in the atmosphere at a temperature of 25°C to 160°C, preferably 80°C to 140°C, is an example. The molded body is thus obtained.

[0115] The CMC of this embodiment can be obtained by firing the resulting molded body. Examples of firing conditions include firing the molded body in an oxidizing atmosphere (preferably an atmospheric atmosphere) at 1050°C to 1300°C (more preferably 1050°C to 1200°C).

[0116] In the CMC manufacturing method of this embodiment, before firing, there may be a pre-firing step of pre-firing the molded body to obtain a pre-firing body, and a heat treatment step of impregnating the pre-firing body in a precursor and then heat-treating it.

[0117] In the pre-firing process, the molded body is pre-fired to obtain a pre-fired body. The pre-firing conditions are any conditions that allow the sintering of the ceramic matrix to take place, such as atmospheric conditions and 600°C to 1000°C (preferably 800°C to 1000°C).

[0118] The CMC obtained through a heat treatment process is further densified. In the heat treatment process, the pre-fired body is impregnated in a precursor and then heat-treated. The precursor can be a compound that densifies the ceramic matrix through heat treatment, or more specifically, a precursor for the ceramic matrix. For example, as a precursor for alumina, one or more selected from the group consisting of polyaluminum chloride, aluminum hydroxide, and aluminum nitrate can be cited, and polyaluminum chloride can be cited more specifically.

[0119] Impregnation preferably involves impregnating the pre-fired body with a solution containing the precursor (preferably an aqueous solution containing the precursor). Impregnation conditions are as long as the aqueous solution is contained in the pores of the pre-fired body, and examples include a reduced pressure atmosphere (preferably a vacuum atmosphere, more preferably a vacuum atmosphere of -0.08 MPaG or less), room temperature, for more than 1 minute and less than 1 hour.

[0120] The pre-burnt body impregnated in the precursor is subjected to heat treatment. The heat treatment conditions are arbitrary, and examples include an oxidizing atmosphere (preferably atmospheric atmosphere) at 600°C to 1000°C (preferably 800°C to 1000°C). The heat treatment time is arbitrary, and examples include 30 minutes to 5 hours.

[0121] The heat treatment process can be repeated, from 1 to 10 times, or even from 1 to 5 times.

[0122] In the case where the CMC manufacturing method of this embodiment includes a pre-firing process and a heat treatment process, the pre-firing body after the heat treatment process can be supplied for firing instead of the molded body.

[0123] As a specific manufacturing method of the CMC of the present invention, for example, when the ceramic matrix is ​​at least one of alumina and mullite, it is preferable to impregnate the metal-ceramic continuous fibers in a raw material slurry containing at least one of alumina and mullite, and then heat-treat it in the atmosphere at a temperature of 600°C to 1000°C to form a pre-fired body, and sinter the pre-fired body in the atmosphere at a temperature of 1050°C to 1300°C to thereby composite it.

[0124] This invention provides ceramic continuous fibers containing metallic elements suitable for manufacturing high-strength CMCs, and CMCs using the same.

[0125] Example The present invention will now be described using examples. However, the present invention is not limited to these examples.

[0126] (ICP emission spectrophotometry) Quantitative analysis of metallic elements in fibers was performed using an ICP-luminescence analyzer (Vista-PRO axial specification, manufactured by Seiko Instruments) under the following conditions.

[0127] Frequency: 40MHz Output power: 1.0kW Detector: CCD detector Sample introduction: pneumatic atomizer Regarding the test sample, the sample was obtained by decomposing 0.1g of continuous ceramic fiber under pressure with sulfuric acid at 230℃ for 144 hours, followed by concentration, volume adjustment, and dilution.

[0128] (Single fiber tensile strength) The tensile strength of a single fiber was determined using a method based on Method B of JIS R 1657. The conditions for determining the tensile strength of a single fiber are shown below.

[0129] Gauge length: 25mm Test speed: 0.5 mm / min (Volume tensile strength) Volumetric tensile strength was determined using the following method based on JIS R 1656. Specifically, a CMC specimen was machined to approximately 10 mm wide × 110 mm long × 2.5 mm thick, and aluminum tabs were attached to both ends to create a tensile test piece. It should be noted that the width and thickness of the tensile test piece were measured using a micrometer, and the length was measured using vernier calipers. The tensile strength was tested using a strength testing machine (device name: AG-XPlus, manufactured by Shimadzu Corporation) and tensile testing fixtures, using the method based on JIS R 1656, at a load speed of 0.5 mm / min.

[0130] (XRD measurement) XRD measurements were performed using a standard powder X-ray diffraction apparatus (Apparatus name: Ultima III, manufactured by Rigaku Corporation). The conditions for XRD measurements are described below.

[0131] X-ray source: CuKα rays (λ=0.15418nm) Measurement mode: Step scan Scanning conditions: 0.04° per second Diverging slit: 2 / 3deg Scattering slit: 2 / 3deg Light-receiving slit: 0.3mm Measurement time: 2.0 seconds Measurement range: 2θ = 20°~80° (Crystal diameter) The crystallite diameter of the elements constituting the continuous ceramic fibers is determined using the following Scherrer formula, based on the XRD pattern obtained by the same method as (XRD determination).

[0132] D=K×λ / ((β-B)×cosθ) In the above formula, D is the average crystallite diameter (nm), K is the Scherrer constant (1.0), λ is the wavelength of CuKα (0.15418nm), β is the integration width (rad), B is the device constant (rad), and θ is the measured diffraction angle. Regarding the device constant, 0.003002 (rad) is used when the raw material fiber is continuous mullite fiber, and 0.002723 (rad) is used when the raw material fiber is continuous alumina fiber. Furthermore, the integration width was determined using Rigaku's IntegralAnalysis for Windows (Version 6.0), and the analysis function used was the segmented voigt function. Regarding the diffraction angles, the diffraction angles of the mullite continuous fiber with a peak at 2θ=68° (2θ=68±0.2°) corresponding to the (300) plane of the hexagonal crystal of alumina, and the diffraction angles of the alumina continuous fiber with a peak at 2θ=35° (2θ=35±0.2°) corresponding to the (104) plane of the hexagonal crystal of alumina, are used.

[0133] Example A1 0.4 g of lanthanum(III) acetylacetone dihydrate (La(CH3COCHCOCH3)3·2H2O; hereinafter also referred to as "La-AcAc complex") was dissolved in 200 mL of ethanol. Mullite fiber cloth (product name: Nextel 720, manufactured by 3M) that had been heat-treated (desized) at 800°C in the atmosphere was then impregnated in the lanthanum AcAc solution for 24 hours at room temperature.

[0134] After impregnation, the impregnated mullite fiber cloth is heat-treated in the atmosphere at 900°C for 2 hours to obtain mullite fiber cloth coated with lanthanum oxide (mullite continuous fiber coated with lanthanum oxide).

[0135] Figure 1 Images (a) through (f) show STEM-EDS images of the surface of the obtained mullite continuous fibers coated with lanthanum oxide. A coating layer of approximately 10 nm thickness was confirmed on the fiber surface. Elemental analysis revealed that the coating layer consists of La and O, and is therefore lanthanum oxide.

[0136] Then, the mullite fiber cloth coated with lanthanum oxide was heat-treated in the atmosphere at 1100°C for 2 hours to obtain the lanthanum-containing ceramic fiber cloth (lanthanum-containing continuous ceramic fiber) of this embodiment.

[0137] Figure 2 STEM-EDS images of the surface of the lanthanum-containing mullite fiber cloth obtained are shown in (a) to (f). Figure 2As confirmed, the lanthanum-containing mullite continuous fibers differ from the precursor (lanthanum oxide-coated mullite continuous fibers) in that they do not have a coating layer on the surface. Furthermore, it was confirmed that the lanthanum is uniformly distributed from the fiber surface to approximately 50 nm (50 ± 25 nm). This is formed by thermal diffusion (grain boundary diffusion) of the lanthanum oxide coating layer of the aforementioned lanthanum oxide-coated mullite fibers.

[0138] The lanthanum-containing mullite continuous fiber has a lanthanum mass concentration (metal content) of approximately 100 ppm (100 ppm) and a doping metal element mass concentration (lanthanum doping content) of 100 ppm. The single fiber tensile strength is 1.7 GPa. In this embodiment, the mullite fiber used as the raw material fiber has a structure formed by two phases: mullite and alumina. The alumina crystallite diameter of this lanthanum-containing mullite continuous fiber (lanthanum-containing mullite-alumina continuous fiber) is 33.8 nm.

[0139] (Evaluation of heat resistance) The lanthanum-containing mullite continuous fibers of this embodiment were heat-treated in the atmosphere at 1300°C for 100 hours. The single fiber tensile strength of the heat-treated lanthanum-containing mullite continuous fibers was 1.3 GPa, and the alumina crystallite diameter was 43.9 nm with a crystallite growth rate of 29.9%.

[0140] On the other hand, the lanthanum-containing mullite continuous fibers of this embodiment were heat-treated in the atmosphere at 1200°C for 100 hours. The heat-treated lanthanum-containing mullite continuous fibers had a lanthanum content of approximately 70 ppm (70 ppm), a doped metal content of 70 ppm, and a single fiber tensile strength of 1.5 GPa. Furthermore, the alumina crystallite diameter was 39.4 nm, and the crystallite growth rate was 16.6%.

[0141] Example A2 Magnesium acetylacetonate(II) hydrate (Mg(CH3COCHCOCH3)2·nH2O) 0.4 g was used instead of the La-AcAc complex, and the magnesium-containing mullite continuous fibers of this embodiment were otherwise obtained by the same method as in Example A1. The raw material fibers used in this embodiment contained 24 ppm of magnesium as an impurity.

[0142] In this embodiment, the mass concentration (magnesium content) of magnesium in the mullite continuous fiber (magnesium-containing mullite continuous fiber) is about 40 ppm, the doped magnesium content is 16 ppm, the single fiber tensile strength is 1.6 GP, and the alumina microcrystal diameter is 36.9 nm.

[0143] (Evaluation of heat resistance) The magnesium-containing mullite continuous fibers of this embodiment are used, except that heat treatment is performed in the same manner as in Example A1.

[0144] For magnesium-containing ceramic continuous fibers heat-treated in the atmosphere at 1200℃ for 100 hours, the magnesium mass concentration is about 31ppm (31ppm), the doped magnesium content is 7ppm, the single fiber tensile strength is 1.4GPa, the alumina crystallite diameter is 38.8nm, and the crystallite growth rate is 5.1%.

[0145] In addition, the single fiber tensile strength of the magnesium-containing mullite continuous fiber after heat treatment in the atmosphere at 1300℃ for 100 hours is 1.3 GPa, the alumina crystallite diameter is 40.2 nm, and the crystallite growth rate is 8.9%.

[0146] Example A3 Instead of the La-AcAc complex, 0.4 g of cerium(III) acetylacetone trihydrate (Ce(CH3COCHCOCH3)3·3H2O) was used. Otherwise, the cerium-containing mullite continuous fibers of this embodiment were obtained by the same method as in Example A1.

[0147] The cerium content in the cerium-containing mullite continuous fiber of this embodiment is about 94 ppm (94 ppm), the cerium doping content is 94 ppm, and the alumina microcrystal diameter is 36.1 nm.

[0148] (Evaluation of heat resistance) The cerium-containing mullite continuous fibers of this embodiment were heat-treated in the atmosphere at 1300°C for 100 hours. The single fiber tensile strength of the heat-treated cerium-containing mullite continuous fibers was 1.2 GPa, the alumina crystallite diameter was 44.2 nm, and the crystallite growth rate was 22.4%.

[0149] Example A4 Instead of the La-AcAc complex, 0.4 g of zirconium acetylacetonate (IV) (Zr(CH3COCHCOCH3)4) was used. Otherwise, the zirconium-containing mullite continuous fibers of this embodiment were obtained by the same method as in Example A1. The raw material fibers used in this embodiment contained 14 ppm of zirconium as an impurity.

[0150] The zirconium content in the mullite continuous fiber is approximately 88 ppm (88 ppm), the zirconium doping content is 74 ppm, and the alumina microcrystal diameter is 34.5 nm.

[0151] (Evaluation of heat resistance) The zirconium-containing mullite continuous fibers of this embodiment were heat-treated in the atmosphere at 1300°C for 100 hours. The single fiber tensile strength of the heat-treated zirconium-containing mullite continuous fibers was 1.2 GPa, the alumina crystallite diameter was 49.4 nm, and the crystallite growth rate was 43.2%.

[0152] Example A5 Instead of the La-AcAc complex, 0.4 g of neodymium acetylacetone (III) (Nd(CH3COCHCOCH3)4) was used. Otherwise, the neodymium-containing mullite continuous fibers of this embodiment were obtained by the same method as in Example A1.

[0153] In this embodiment, the neodymium content in the neodymium-containing mullite continuous fiber is about 64 ppm (64 ppm), the neodymium doping content is 64 ppm, and the alumina microcrystal diameter is 41.2 nm.

[0154] (Evaluation of heat resistance) The neodymium-containing mullite continuous fibers of this embodiment were heat-treated in the atmosphere at 1300°C for 100 hours. The alumina crystallite diameter of the heat-treated neodymium-containing mullite continuous fibers was 49.4 nm, and the crystallite growth rate was 19.9%.

[0155] Example A6 Instead of the La-AcAc complex, 0.3 g of strontium(II) acetylacetone hydrate (Sr(CH3COCHCOCH3)2·nH2O) was used. Otherwise, the strontium-containing mullite continuous fibers of this embodiment were obtained by the same method as in Example A1.

[0156] In this embodiment, the strontium content in the strontium-containing mullite continuous fiber is about 80 ppm (80 ppm), the doped strontium content is 80 ppm, and the alumina microcrystal diameter is 40.0 nm.

[0157] (Evaluation of heat resistance) The strontium-containing mullite continuous fibers of this embodiment were heat-treated in the atmosphere at 1300°C for 100 hours. After heat treatment, the alumina crystallite diameter of the strontium-containing mullite continuous fibers of this embodiment was 47.4 nm, and the crystallite growth rate was 18.5%.

[0158] Example A7 Instead of the La-AcAc complex, 0.4 g of yttrium(III)n hydrate (Y(CH3COCHCOCH3)3·nH2O) was used. Otherwise, the yttrium-containing mullite continuous fibers of this embodiment were obtained by the same method as in Example A1.

[0159] In this embodiment, the yttrium content in the yttrium-containing mullite continuous fiber is about 76 ppm (76 ppm), the doped yttrium content is 76 ppm, and the alumina microcrystal diameter is 33.3 nm.

[0160] (Evaluation of heat resistance) The yttrium-containing mullite continuous fibers of this embodiment were heat-treated in the atmosphere at 1300°C for 100 hours. The tensile strength of the single fiber of the heat-treated yttrium-containing mullite continuous fibers was 1.2 GPa, the alumina crystallite diameter was 44.4 nm, and the crystallite growth rate was 33.3%.

[0161] Example A8 Instead of the La-AcAc complex, 0.4 g of ytterbium(III) hydrate (Yb(CH3COCHCOCH3)3·nH2O) was used. Otherwise, the ytterbium-containing mullite continuous fibers of this embodiment were obtained by the same method as in Example A1.

[0162] The ytterbium content of the ytterbium-containing mullite continuous fiber in this embodiment is 77 ppm, the doped ytterbium content is 77 ppm, and the alumina microcrystal diameter is 41.2 nm.

[0163] Figure 3 The image shows the STEM-EDS spectra of the grain boundaries of the ytterbium-containing mullite continuous fibers constituting this embodiment. Figure 3 As indicated by "※" in (b), ytterbium spectra were detected at the grain boundaries constituting the interior of the fiber. This confirms that the ytterbium-containing mullite continuous fiber of this embodiment contains ytterbium at its grain boundaries.

[0164] (Evaluation of heat resistance) The ytterbium-containing mullite continuous fibers of this embodiment were heat-treated in the atmosphere at 1300°C for 100 hours. The tensile strength of the single fiber of the heat-treated ytterbium-containing mullite continuous fibers was 1.4 GPa, the alumina crystallite diameter was 69.5 nm, and the crystallite growth rate was 68.7%.

[0165] Example A9 Instead of the La-AcAc complex, 0.4 g of lutetium acetylacetonate (III) hydrate (Lu(CH3COCHCOCH3)3·nH2O) was used. Otherwise, the lutetium-containing mullite continuous fibers of this embodiment were obtained by the same method as in Example A1.

[0166] In this embodiment, the lutetium content in the lutetium-containing mullite continuous fiber is 120 ppm, the doped lutetium content is 120 ppm, the single fiber tensile strength is 1.8 GPa, and the alumina microcrystal diameter is 36.2 nm.

[0167] (Evaluation of heat resistance) The lutetium-containing mullite continuous fibers of this embodiment were heat-treated in the atmosphere at 1300°C for 100 hours. The single fiber tensile strength of the heat-treated lutetium-containing mullite continuous fibers was 1.2 GPa, the alumina crystallite diameter was 62.0 nm, and the crystallite growth rate was 71.3%.

[0168] Example A10 Instead of the La-AcAc complex, 0.25 g of calcium acetylacetonate (II) hydrate (Ca(CH3COCHCOCH3)2·nH2O) was used, and the calcium-containing mullite continuous fibers of this embodiment were obtained by the same method as in Example A1. The raw material fibers used in this embodiment contained 21 ppm of calcium as an impurity.

[0169] In this embodiment, the calcium content of the calcium-containing mullite continuous fiber is 61 ppm, the doped calcium content is 40 ppm, the single fiber tensile strength is 1.6 GPa, and the alumina microcrystal diameter is 39.5 nm.

[0170] (Evaluation of heat resistance) The calcium-containing mullite continuous fibers of this embodiment were heat-treated in the atmosphere at 1300°C for 100 hours. The single fiber tensile strength of the heat-treated calcium-containing mullite continuous fibers was 1.3 GPa, the alumina crystallite diameter was 61.6 nm, and the crystallite growth rate was 55.9%.

[0171] Example A11 Magnesium-containing mullite fibers obtained by the same method as in Example A2 were subjected to the same treatment as in Example A9 to obtain continuous mullite fibers containing magnesium and lutetium of this embodiment. The raw material fibers used in this embodiment contain 24 ppm of magnesium as an impurity.

[0172] The magnesium and lutetium-containing mullite continuous fibers contain 40 ppm magnesium and 120 ppm lutetium, with 16 ppm magnesium doping and 120 ppm lutetium doping. The single fiber tensile strength is 1.7 GPa, and the alumina microcrystal diameter is 38.6 nm.

[0173] (Evaluation of heat resistance) The magnesium- and lutetium-containing mullite continuous fibers of this embodiment were heat-treated in the atmosphere at 1300°C for 100 hours. The single fiber tensile strength of the heat-treated magnesium- and lutetium-containing mullite continuous fibers was 1.2 GPa, the alumina crystallite diameter was 62.7 nm, and the crystallite growth rate was 62.4%.

[0174] Comparative Example A1 (mullite continuous fibers) Commercially available mullite fiber cloth (the mullite continuous fiber used in Example A1) was desized by heat treatment at 800°C in air to produce the mullite fiber cloth (mullite continuous fiber) of this comparative example. The single fiber tensile strength of the mullite continuous fiber of this comparative example is 1.7 GPa, and the alumina microcrystal diameter is 36.9 nm.

[0175] (Evaluation of heat resistance) The mullite fiber cloth of this comparative example was heat-treated in the atmosphere at 1200°C for 100 hours.

[0176] The heat-treated mullite fiber cloth has a single fiber tensile strength of 1.3 GPa, an alumina microcrystal diameter of 43.4 nm, and a microcrystal growth rate of 17.6%.

[0177] In addition, the mullite fiber cloth of this comparative example was heat-treated in the atmosphere at 1300°C for 100 hours. The single fiber tensile strength of the heat-treated mullite fiber cloth was 1.0 GPa, the alumina crystallite diameter was 59.6 nm, and the crystallite growth rate was 61.5%.

[0178] The above description demonstrates that, compared to the commercially available mullite continuous fiber of Comparative Example A1, the metal-containing mullite continuous fibers of Examples A1 to A11 exhibit suppressed alumina crystal growth and maintained fiber strength even under the same heat treatment. Therefore, it can be confirmed that the ceramic-containing mullite continuous fibers of Examples A1 to A11 possess higher heat resistance than commercially available mullite continuous fibers.

[0179] Comparative Example A2 Desizing was performed by heat treatment of commercially available mullite fiber cloth (the mullite continuous fiber used in Example A1) at 800°C in air. The heat treatment was then performed at 900°C in air for 2 hours, followed by heat treatment at 1100°C in air for 2 hours to produce the mullite fiber cloth (mullite continuous fiber) of this comparative example. The single fiber tensile strength of the mullite continuous fiber of this comparative example was 1.7 GPa, and the alumina crystallite diameter was 37.8 nm.

[0180] (Evaluation of heat resistance) The mullite fiber cloth of this comparative example was heat-treated in the atmosphere at 1300°C for 100 hours. The tensile strength of a single fiber of the heat-treated mullite fiber cloth was 1.0 GPa, the diameter of alumina crystallites was 60.2 nm, and the crystallite growth rate was 59.3%.

[0181] It can be confirmed that, compared with the metal-containing mullite continuous fibers of the embodiments, the single fiber tensile strength of the heat-treated mullite continuous fibers of this comparative example is lower.

[0182] Example A12 As the raw material fiber, an alumina fiber cloth (3M, Nextel 610) that had been desized by heat treatment at 800°C in the atmosphere was used. Otherwise, the lanthanum-containing continuous alumina fiber of this embodiment was obtained by the same method as in Example A1.

[0183] In this embodiment, the lanthanum content in the lanthanum-containing alumina continuous fiber is approximately 130 ppm (130 ppm), the doped lanthanum content is 130 ppm, and the alumina microcrystal diameter is 85.0 nm.

[0184] (Evaluation of heat resistance) The lanthanum-containing alumina continuous fibers of this embodiment were heat-treated in the atmosphere at 1300°C for 100 hours. The tensile strength of the single fiber of the heat-treated lanthanum-containing alumina continuous fibers was 1.2 GPa, the alumina crystallite diameter was 181.7 nm, and the crystallite growth rate was 113.8%.

[0185] Example A13 Instead of the La-AcAc complex, 0.4 g of magnesium(II) acetylacetonate hydrate (Mg(CH3COCHCOCH3)2·nH2O) was used, and the magnesium-containing alumina continuous fibers of this embodiment were obtained by the same method as in Example A12. The raw material fibers used in this embodiment contained 25 ppm of magnesium as an impurity.

[0186] In this embodiment, the magnesium content in the magnesium-containing alumina continuous fiber is about 34 ppm (34 ppm), the doped magnesium content is 9 ppm, and the alumina microcrystal diameter is 76.0 nm.

[0187] (Evaluation of heat resistance) The magnesium-containing alumina continuous fibers of this embodiment were heat-treated in atmospheric conditions at 1300°C for 100 hours. The tensile strength of a single fiber of the heat-treated magnesium-containing alumina continuous fibers was 1.1 GPa, the alumina crystallite diameter was 130.5 nm, and the crystallite growth rate was 71.7%.

[0188] Example A14 Instead of the La-AcAc complex, 0.4 g of calcium acetylacetonate (II) hydrate (Ca(CH3COCHCOCH3)2·nH2O) was used. Otherwise, the calcium-containing alumina continuous fibers of this embodiment were obtained by the same method as in Example A12. The raw material fibers used in this embodiment contained 20 ppm of calcium as an impurity.

[0189] In this embodiment, the calcium content in the calcium-containing alumina continuous fiber is about 40 ppm (40 ppm), the doped calcium content is 20 ppm, and the alumina microcrystal diameter is 79.9 nm.

[0190] Figure 4 The image shows the STEM-EDS spectra of the grain boundaries of the calcium-containing alumina continuous fibers constituting this embodiment. Figure 4 As indicated by "※" in (b), a spectrum of calcium was detected at the grain boundaries constituting the interior of the fiber. This confirms that the calcium-containing alumina continuous fiber of this embodiment contains calcium at its grain boundaries.

[0191] (Evaluation of heat resistance) The calcium-containing alumina continuous fibers of this embodiment were heat-treated in atmospheric conditions at 1300°C for 100 hours. The tensile strength of a single fiber of the heat-treated calcium-containing alumina continuous fibers was 1.2 GPa, the alumina crystallite diameter was 132.4 nm, and the crystallite growth rate was 65.7%.

[0192] Example A15 Instead of the La-AcAc complex, 0.4 g of neodymium acetylacetone (III) (Nd(CH3COCHCOCH3)4) was used. Otherwise, the neodymium-containing alumina continuous fibers of this example were obtained by the same method as in Example A12.

[0193] In this embodiment, the neodymium content in the neodymium-containing alumina continuous fiber is about 63 ppm (63 ppm), the neodymium doping content is 63 ppm, and the alumina microcrystal diameter is 78.0 nm.

[0194] (Evaluation of heat resistance) The neodymium-containing alumina continuous fibers of this embodiment were heat-treated in the atmosphere at 1300°C for 100 hours. The tensile strength of the single fiber of the heat-treated neodymium-containing alumina continuous fibers was 1.1 GPa, the alumina crystallite diameter was 201.4 nm, and the crystallite growth rate was 158.2%.

[0195] Example A16 Instead of the La-AcAc complex, 0.4 g of zirconium acetylacetonate (IV) (Zr(CH3COCHCOCH3)4) was used. Otherwise, the zirconium-containing alumina continuous fibers of this example were obtained by the same method as in Example A12.

[0196] In this embodiment, the zirconium content in the zirconium-containing alumina continuous fiber is about 35 ppm (35 ppm), the zirconium doping content is 35 ppm, and the alumina microcrystal diameter is 78.0 nm.

[0197] Figure 5 The image shows the STEM-EDS spectra of the grain boundaries of the alumina constituting the zirconium-containing alumina continuous fibers of this embodiment. Figure 5 As indicated by "※" in (b), zirconium spectra were detected at the grain boundaries constituting the interior of the fiber. This confirms that the zirconium-containing aluminum continuous fiber of this embodiment contains zirconium at its grain boundaries.

[0198] (Evaluation of heat resistance) The zirconium-containing alumina continuous fibers of this embodiment were heat-treated in the atmosphere at 1300°C for 100 hours. The tensile strength of a single fiber of the heat-treated zirconium-containing alumina continuous fibers was 1.2 GPa, the alumina crystallite diameter was 117.3 nm, and the crystallite growth rate was 50.4%.

[0199] Example A17 Instead of the La-AcAc complex, 0.3 g of strontium(II) acetylacetone hydrate (Sr(CH3COCHCOCH3)2·nH2O) was used. Otherwise, the strontium-containing alumina continuous fibers of this example were obtained by the same method as in Example A12.

[0200] In this embodiment, the strontium content in the strontium-containing alumina continuous fiber is about 100 ppm (100 ppm), the doped strontium content is 100 ppm, and the alumina microcrystal diameter is 79.0 nm.

[0201] (Evaluation of heat resistance) The strontium-containing alumina continuous fibers of this embodiment were heat-treated in the atmosphere at 1300°C for 100 hours. The tensile strength of the single fiber of the heat-treated strontium-containing alumina continuous fibers was 1.2 GPa, the alumina crystallite diameter was 149.4 nm, and the crystallite growth rate was 89.1%.

[0202] Example A18 Instead of the La-AcAc complex, 0.4 g of yttrium(III)n hydrate (Y(CH3COCHCOCH3)3·nH2O) was used. Otherwise, the yttrium-containing alumina continuous fibers of this example were obtained by the same method as in Example A12.

[0203] In this embodiment, the yttrium content in the yttrium-containing alumina continuous fiber is about 60 ppm (60 ppm), the doped yttrium content is 60 ppm, and the alumina microcrystal diameter is 78.0 nm.

[0204] (Evaluation of heat resistance) The yttrium-containing alumina continuous fibers of this embodiment were heat-treated in atmospheric conditions at 1300°C for 100 hours. The alumina crystallite diameter of the heat-treated yttrium-containing alumina continuous fibers was 151.9 nm, and the crystallite growth rate was 94.7%.

[0205] Example A19 Instead of the La-AcAc complex, 0.4 g of lutetium acetylacetonate (Lu(CH3COCHCOCH3)3·nH2O) hydrate was used. Otherwise, the lutetium-containing alumina continuous fibers of this embodiment were obtained by the same method as in Example A12.

[0206] In this embodiment, the lutetium content in the lutetium-containing continuous alumina fiber is 120 ppm, the doped lutetium content is 120 ppm, and the alumina microcrystal diameter is 78.0 nm.

[0207] (Evaluation of heat resistance) The lutetium-containing alumina continuous fibers of this embodiment were heat-treated in atmospheric conditions at 1300°C for 100 hours. The alumina crystallite diameter of the heat-treated lutetium-containing alumina continuous fibers was 157.1 nm, and the crystallite growth rate was 101.4%.

[0208] Example A20 The same method as in Example A19 was repeated three times to obtain the lutetium-containing continuous alumina fibers of this embodiment. Specifically, at room temperature, the lutetium-containing continuous alumina fibers obtained by the same method as in Example A19 were immersed in a lutetium acetylacetone solution for 24 hours, and then the operation of heat treatment at 900°C for 2 hours in the atmosphere and further heat treatment at 1100°C for 2 hours in the atmosphere was repeated twice to produce the lutetium-containing continuous alumina fibers of this embodiment.

[0209] In this embodiment, the lutetium content in the lutetium-containing continuous alumina fiber is 380 ppm, the doped lutetium content is 380 ppm, and the alumina microcrystal diameter is 75.0 nm.

[0210] (Evaluation of heat resistance) The lutetium-containing alumina continuous fibers of this embodiment were heat-treated in atmospheric conditions at 1300°C for 100 hours. The alumina crystallite diameter of the heat-treated lutetium-containing alumina continuous fibers was 106.5 nm, and the crystallite growth rate was 42.0%.

[0211] Example A21 Instead of the La-AcAc complex, 0.4 g of ytterbium(III) hydrate (Yb(CH3COCHCOCH3)3·nH2O) was used, and the ytterbium-containing continuous alumina fibers of this embodiment were obtained by the same method as in Example A12.

[0212] In this embodiment, the ytterbium content in the ytterbium-containing continuous alumina fiber is 77 ppm, the doped ytterbium content is 77 ppm, and the alumina microcrystal diameter is 78.0 nm.

[0213] (Evaluation of heat resistance) The ytterbium-containing alumina continuous fibers of this embodiment were heat-treated in atmospheric conditions at 1300°C for 100 hours. The alumina crystallite diameter of the heat-treated ytterbium-containing alumina continuous fibers was 117.4 nm, and the crystallite growth rate was 47.1%.

[0214] Example A22 The zirconium-containing continuous alumina fibers obtained by the same method as in Example A16 were subjected to the same treatment as in Example A14 to obtain the zirconium- and calcium-containing continuous alumina fibers of this example. The raw material fibers used in this example contain 20 ppm of calcium as an impurity.

[0215] The continuous alumina fiber containing zirconium and calcium has a zirconium content of 27 ppm, a calcium content of 110 ppm, a doped zirconium content of 27 ppm, a doped calcium content of 90 ppm, a single fiber tensile strength of 2.3 GPa, and an alumina microcrystal diameter of 78.0 nm.

[0216] (Evaluation of heat resistance) The zirconium and calcium-containing alumina continuous fibers of this embodiment were heat-treated in the atmosphere at 1300°C for 100 hours. The single fiber tensile strength of the heat-treated zirconium and calcium-containing alumina continuous fibers was 1.3 GPa, the alumina crystallite diameter was 128.7 nm, and the crystallite growth rate was 65.0%.

[0217] Example A23 The zirconium-containing alumina continuous fibers obtained by the same method as in Example A16 were subjected to the same treatment as in Example A17 to obtain the zirconium and strontium-containing alumina continuous fibers of this embodiment.

[0218] The continuous alumina fiber containing zirconium and strontium has a zirconium content of 80 ppm, a strontium content of 190 ppm, a doped zirconium content of 80 ppm, a doped strontium content of 190 ppm, a single fiber tensile strength of 2.4 GPa, and an alumina microcrystal diameter of 76.0 nm.

[0219] (Evaluation of heat resistance) The zirconium and strontium-containing alumina continuous fibers of this embodiment were heat-treated in the atmosphere at 1300°C for 100 hours. The tensile strength of the single fiber of the heat-treated zirconium and strontium-containing alumina continuous fibers was 1.2 GPa, the alumina crystallite diameter was 120.3 nm, and the crystallite growth rate was 58.3%.

[0220] Example A24 The zirconium-containing alumina continuous fibers obtained by the same method as in Example A16 were subjected to the same treatment as in Example A16 four times to obtain the zirconium-containing alumina continuous fibers of this embodiment. That is, at room temperature, the zirconium-containing alumina continuous fibers obtained by the same method as in Example A16 were immersed in a zirconium acetylacetone solution for 24 hours, and then the operation of heat treatment at 900°C for 2 hours in the atmosphere and further heat treatment at 1100°C for 2 hours in the atmosphere was repeated four times to produce the zirconium-containing alumina continuous fibers of this embodiment.

[0221] In this embodiment, the zirconium-containing alumina continuous fiber has a zirconium content of 200 ppm, a zirconium doping content of 200 ppm, and an alumina microcrystal diameter of 78.0 nm.

[0222] (Evaluation of heat resistance) The zirconium-containing alumina continuous fibers of this embodiment were heat-treated in atmospheric conditions at 1300°C for 100 hours. The single-fiber tensile strength of the heat-treated zirconium-containing alumina continuous fibers was 1.3 GPa, the alumina crystallite diameter was 149.5 nm, and the crystallite growth rate was 91.7%.

[0223] Comparative Example A3 The commercially available alumina fiber cloth used in Example A12 was heat-treated (desizing) at 800°C in air to produce the alumina fiber cloth (continuous alumina fiber) of this comparative example. The single fiber tensile strength of the continuous alumina fiber of this comparative example is 2.1 GPa, and the alumina crystallite diameter is 77.2 nm.

[0224] (Evaluation of heat resistance) The alumina fiber cloth of this comparative example was heat-treated in the atmosphere at 1300°C for 100 hours. The tensile strength of a single fiber of the heat-treated alumina fiber cloth was 1.0 GPa. The diameter of the alumina crystallites was 226.0 nm, and the crystallite growth rate was 192.7%.

[0225] Comparative Example A4 0.4 g of zirconium acetylacetonate (IV) (Zr(CH3COCHCOCH3)4) was dissolved in 200 mL of ethanol. At room temperature, alumina fiber cloth (product name: Nextel 610, manufactured by 3M) that had been heat-treated (desized) at 800°C in the atmosphere was impregnated in the zirconium AcAc solution for 24 hours.

[0226] After impregnation, the impregnated alumina fiber cloth is heat-treated in the atmosphere at 900°C for 2 hours to obtain continuous alumina fibers coated with zirconium oxide.

[0227] Figure 6 The results of STEM-EDS spectra of the grain boundaries of the zirconium-coated alumina continuous fibers constituting this comparative example are shown. No zirconium spectra were detected at the grain boundaries within the fibers. This confirms that the zirconium-coated alumina continuous fibers obtained by heat treatment at 900°C for 2 hours do not contain zirconium at their grain boundaries.

[0228] The above description demonstrates that, compared to the commercially available alumina continuous fibers of Comparative Example A2, the growth of alumina microcrystals in the metal-containing alumina continuous fibers of Examples A12 to A24 was suppressed even under the same heat treatment. Therefore, it can be confirmed that the metal-containing alumina continuous fibers of Examples A12 to A24 have higher heat resistance than commercially available alumina continuous fibers.

[0229] Example B1 An alumina slurry was obtained by mixing 181.9 g of α-alumina powder with an average particle size of 0.19 μm, 5.6 g of silica powder with an average particle size of 0.20 μm, and 58 g of pure water in a ball mill for 24 hours. This slurry was then impregnated with an article obtained by laminating five sheets of lanthanum-containing mullite continuous fiber cloth obtained in Example A1, and heated at 120°C for 4 hours. The heated product was dried at 120°C in air to obtain a molded body with a width of 130 mm × a length of 110 mm × a thickness of approximately 2.5 mm. After drying the molded body in air at 120°C for 2 days, it was heat-treated in air at 900°C for 2 hours, followed by heat treatment in air at 1100°C for 2 hours. Finally, it was heat-treated in air at 1200°C for 100 hours to obtain plate-shaped CMC. The density of the obtained CMC was determined using Archimedes' method. The density is 2.48 g / cm³. 3 The fiber volume fraction is 33.8%, and the volumetric tensile strength is 176 MPa.

[0230] Example B2 Instead of the lanthanum-containing mullite continuous fiber cloth, the magnesium-containing mullite continuous fiber cloth obtained in Example A2 was used. Furthermore, a sheet-like CMC was obtained using the same method as in Example B1 and used as the CMC in this example. The density of the obtained CMC was 2.58 g / cm³. 3 The fiber volume fraction is 35.0%, and the volumetric tensile strength is 158 MPa.

[0231] Furthermore, the CMC of this embodiment was heat-treated in the atmosphere at 1300°C for 100 hours. The volumetric tensile strength of the heat-treated CMC was 87 MPa and the volumetric tensile strength was 71 MPa. Further, the CMC of this embodiment was heat-treated in the atmosphere at 1200°C for 100 hours. The volumetric tensile strength of the heat-treated CMC was 152 MPa, confirming that there was almost no strength degradation caused by heat treatment at around 1200°C.

[0232] Example B3 Instead of lanthanum-containing mullite continuous fiber cloth, ytterbium-containing mullite continuous fibers obtained in Example A8 were used. Furthermore, plate-shaped CMC was obtained using the same method as in Example B1 and used as the CMC in this example. The density of the obtained CMC was 2.59 g / cm³. 3 The fiber volume fraction is 42.0%, and the volumetric tensile strength is 179 MPa.

[0233] Example B4 Instead of the lanthanum-containing mullite continuous fiber cloth, the zirconium-containing alumina continuous fiber cloth obtained in Example A16 was used. Furthermore, a sheet-like CMC was obtained using the same method as in Example B1, and this was used as the CMC in this example. The density of the obtained CMC was 2.78 g / cm³. 3 The fiber volume fraction is 41.5%, and the volumetric tensile strength is 238 MPa.

[0234] The CMC of this embodiment was heat-treated at 1300°C for 100 hours in atmospheric conditions. The volumetric tensile strength of the heat-treated CMC was 207 MPa, and the volumetric tensile strength difference was 31 MPa. This confirms that the strength degradation caused by heat treatment is less compared to the CMC of Comparative Example B1, which used commercially available alumina continuous fibers. Furthermore, the CMC of this embodiment was heat-treated at 1200°C for 1000 hours in atmospheric conditions. The volumetric tensile strength of the heat-treated CMC was 231 MPa, confirming that there is almost no strength degradation caused by prolonged heat treatment at around 1200°C.

[0235] Example B5 Instead of the lanthanum-containing mullite continuous fiber cloth, a magnesium-containing alumina continuous fiber cloth obtained in Example A13 was used. Furthermore, a sheet-like CMC was obtained using the same method as in Example B1, and this was used as the CMC in this example. The density of the obtained CMC was 2.75 g / cm³. 3 The fiber volume fraction is 37.5%, and the volumetric tensile strength is 217 MPa.

[0236] The CMC of this embodiment was heat-treated in atmospheric conditions at 1300°C for 100 hours. The volumetric tensile strength of the heat-treated CMC was 176 MPa, and the volumetric tensile strength difference was 41 MPa. It can be confirmed that the strength degradation is less compared with the CMC of Comparative Example B1, which used commercially available alumina continuous fibers.

[0237] Comparative Example B1 Instead of lanthanum-containing mullite continuous fiber cloth, commercially available alumina continuous fiber cloth (the alumina fiber cloth (alumina continuous fiber) of Comparative Example A3) was used. Otherwise, a sheet-like CMC was obtained using the same method as in Example B1 and used as the CMC of this comparative example. The density of the obtained CMC was 2.73 g / cm³. 3 The fiber volume fraction is 41.3%, and the volumetric tensile strength is 202 MPa.

[0238] The CMC of this comparative example was heat-treated in the atmosphere at 1300°C for 100 hours. The volumetric tensile strength of the heat-treated CMC was 132 MPa, and the volumetric tensile strength difference was 70 MPa. This confirms that the strength was significantly degraded due to the heat treatment at 1300°C.

[0239] From the above, it can be confirmed that, regarding the ceramic continuous fibers containing metal elements, as described in Examples A1 to A24, the growth of alumina microcrystals after heat treatment can be suppressed. Furthermore, in the examples of metal-containing ceramic continuous fibers, the decrease in single-fiber tensile strength due to heat treatment is small. In contrast, the decrease in single-fiber tensile strength after heat treatment of commercially available ceramic continuous fibers is large, indicating that the heat resistance of the ceramic continuous fibers containing metal elements of the present invention is superior after heat treatment.

[0240] Furthermore, it was determined that the CMCs using ceramic continuous fibers containing metallic elements in Examples B1 to B5 have higher heat resistance than CMCs using commercially available ceramic continuous fibers.

[0241] These results confirm that the ceramic continuous fibers containing metallic elements of the present invention are suitable for manufacturing ceramic matrix composites with sufficiently high strength.

[0242] Industrial availability The ceramic continuous fibers containing metallic elements of the present invention can improve the heat resistance of commercially available ceramic continuous fibers and can be used as CMCs with high tensile strength. Furthermore, the ceramic continuous fibers containing metallic elements of the present invention can be manufactured by impregnating the continuous fibers in a solvent containing a metal acetylacetone complex and then subjecting them to heat treatment. Therefore, in addition to two-dimensional fabrics, even three-dimensional complex-shaped fabrics and nonwoven fabrics can be easily processed with this additive, enabling its widespread industrial application.

[0243] The entire contents of the description, claims, drawings and abstract of Japanese Patent Application No. 2020-162889, filed on September 29, 2020, and Japanese Patent Application No. 2021-055040, filed on March 29, 2021, are incorporated herein by reference as part of the disclosure of this publication.

Claims

1. A continuous ceramic fiber, characterized in that, The ceramic continuous fiber contains a metal element having a mass concentration of more than 10 ppm and less than 1000 ppm, and the metal element is present at the grain boundaries of the ceramic constituting the ceramic continuous fiber.

2. The ceramic continuous fiber as described in claim 1, wherein, The metallic element is any metallic element other than iron and aluminum.

3. The ceramic continuous fiber as described in claim 1 or 2, wherein, The metallic element is selected from one or more of the group consisting of sodium, potassium, magnesium, calcium, strontium, barium, lanthanum, cerium, praseodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, yttrium, zirconium, neodymium, titanium, scandium, vanadium, chromium, manganese, cobalt, nickel, and copper.

4. The ceramic continuous fiber as described in any one of claims 1 to 3, wherein, The metallic element is selected from one or more of the group consisting of lanthanum, ytterbium, lutetium, magnesium, cerium, zirconium, neodymium, titanium, calcium, yttrium, and strontium.

5. The ceramic continuous fiber as described in any one of claims 1 to 4, wherein, The metallic element is in at least one of the states of grain boundary diffusion and substitution solid solution.

6. The ceramic continuous fiber as described in any one of claims 1 to 5, wherein, The ceramic continuous fiber is a continuous fiber containing at least alumina.

7. The ceramic continuous fiber as described in any one of claims 1 to 6, wherein, After heat treatment under atmospheric conditions at 1300℃ for 100 hours, the growth rate of microcrystals calculated by the following formula (1) is less than 160%. G = {(d b -d a ) / d a }×100 ···(1) G represents the growth rate of microcrystals (%), d a The crystallite diameter (nm) of the material constituting the ceramic continuous fiber before heat treatment, and d b The crystallite diameter (nm) of the material constituting the fiber in the heat-treated ceramic continuous fiber.

8. The ceramic continuous fiber as described in any one of claims 1 to 7, characterized in that, The ceramic continuous fiber is either alumina continuous fiber or mullite continuous fiber.

9. A ceramic matrix composite material, characterized in that, The ceramic continuous fiber used in any one of claims 1 to 8.

10. The ceramic matrix composite material as described in claim 9, wherein, The ceramic matrix constituting the ceramic matrix composite material is selected from at least one of the group consisting of alumina, mullite, zirconium oxide and silicon dioxide.

11. The ceramic matrix composite material as described in claim 9 or 10, wherein, The difference in volumetric tensile strength before and after heat treatment at atmospheric temperature, 1300℃, and for 100 hours is less than 100 MPa.

12. The method for manufacturing continuous ceramic fibers as described in any one of claims 1 to 8, characterized in that, It includes the following processes: an impregnation process in which continuous ceramic fibers are immersed in a solution containing a metal acetylacetone complex; and a heat treatment process at a temperature of 950°C to 1300°C.

13. The method for manufacturing continuous ceramic fibers as described in claim 12, wherein, The metal acetylacetone complex is an acetylacetone complex containing one or more of the following: lanthanum, ytterbium, lutetium, magnesium, zirconium, cerium, yttrium, titanium, sodium, potassium, calcium, scandium, vanadium, chromium, manganese, cobalt, nickel, copper, zinc, gallium, and strontium.

14. A method for manufacturing ceramic matrix composite materials, characterized in that, The ceramic continuous fiber as described in any one of claims 1 to 8 is composited with a ceramic matrix.

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