JP4616442B2 - Carbonaceous material having oxidation-resistant protective layer and method for producing the same - Google Patents

Description

【００４６】
上記の表から明らかな通り、Ｂ₄Ｃ（炭化ホウ素）／アルミナからなる耐酸化保護層を形成した場合には、長時間８００℃以上の高温に曝す条件下で使用しても、実質的な変化は、質量、外観共に認められなかった。しかし、Ｂ₄Ｃ（炭化ホウ素）／アルミナ／ジルコニアからなる保護層の場合には、重量変化は、極めて少なかったが、表面にひび割れが生じていた。しかしながら、図５に示した結果を併せ考慮すれば、乾燥条件下で使用する様な用途では、充分使用可能と判断された。勿論、炭化ホウ素のみからなる耐酸化保護層の場合には、折角、酸化ホウ素が酸化の結果生成しても、炭素繊維との濡れ性がよくないために、保持されることなく流失してしまうことから、大気中で８００℃以上の高温に曝す条件下での使用は実質的に不可能であることは明らかである。なお、上記のように、炭化ホウ素に、アルミナ、または、アルミナ／ジルコニアからなるマイクロクラック内在保護層を設けることにより、炭化ホウ素が酸化されて酸化ホウ素が生成しても、この保護層に保持されて流失しないために、耐酸化性が著しく向上するものと考えられる。
【００４７】
（５）耐酸化保護層の形成▲４▼
上記（３）耐酸化保護層の形成▲２▼において、アルミナの代わりにパイレックス（登録商標）ガラスを溶射して、厚さ５０μｍのアルミナの耐酸化保護層の代わりに、厚さ５０μｍのパイレックスガラス層からなる耐酸化保護層を炭化ホウ素層の上に形成した複合部材を製造した。この試験片を上記の耐酸化性の測定試験に供しところ、８０時間後でも重量に変化は殆ど認められなかった。
【００４８】
【発明の効果】
上記の試験結果から明らかなように、本発明に係る耐酸化保護層が形成された炭素質材料の場合には、高温における高強度（高い耐熱衝撃性）と、材料としての高い信頼性（靱性、耐衝撃性、耐摩耗性）、耐環境性（耐食性、耐酸化性、耐放射線性）等に優れていることはいうまでもない。加えて、基体としてＣ／Ｃコンポジット、あるいは、同コンポジットに金属珪素を含浸処理して製造したＳｉ−ＳｉＣ系複合材料、またはＳｉＣ系複合材料を使用しているので、大気中での耐高温特性に加えて、軽量で、容作業性が要求される分野、各種窯道具等の器具、例えば、プラズマデスプレー用パネルの製造に使用されるセッター等として極めて優れた材料であることはいうまでもない。
【図面の簡単な説明】
【図１】 本発明に係る耐酸化保護層を有する炭素質材料の基体として使用する、Ｓｉ−ＳｉＣ系複合材料およびＳｉＣ系複合材料の基本構造をなすヤーン集合体の構造を模式的に示す斜視図である。
【図２】 （ａ）は、Ｓｉ−ＳｉＣ系複合材料を図１のＩＩａ−ＩＩａ線で切断した場合の断面図であり、（ｂ）は、同材料を図１のＩＩｂ−ＩＩｂ線で切断した場合の断面図である。
【図３】 （ａ）は、ＳｉＣ系複合材料を図１のＩＩａ−ＩＩａ線で切断した場合の断面図であり、（ｂ）は、同材料を図１のＩＩｂ−ＩＩｂ線で切断した場合の断面図である。
【図４】 本発明に係る耐酸化保護層を有する炭素質材料の一態様である炭化ホウ素／アルミナからなる保護層を有する炭素質材料の耐酸化性の測定試験の結果を示すグラフである。
【図５】 本発明に係る耐酸化保護層を有する炭素質材料の別の態様である炭化ホウ素／アルミナ／ジルコニアからなる保護層を有する炭素質材料の耐酸化性の測定試験の結果を示すグラフである。
【符号の説明】
１Ａ、１Ｂ、１Ｃ、１Ｄ、１Ｅおよび１Ｆ…ヤーン配列体、２Ａ…ヤーン、２Ｂ…ヤーン、３…繊維束（ヤーン）、４Ａ…炭化珪素相、４Ｂ…炭化珪素相、４Ｃ…炭化珪素相、５Ａ…Ｓｉ−ＳｉＣ系材料相、５Ｂ…Ｓｉ−ＳｉＣ系材料相、５Ｃ…Ｓｉ−ＳｉＣ系材料相、６…ヤーン集合体、７…繊維複合材料、８Ａ…マトリックス、８Ｂ…マトリックス、１１Ａ、１１Ｂ、１１Ｃ、１１Ｄ、１１Ｅおよび１１Ｆ…ヤーン配列体、１２Ａ…ヤーン、１２Ｂ…ヤーン、１３…繊維束（ヤーン）、１４…炭化珪素相、１５…空隙、１６…ヤーン集合体、１７…繊維複合材料、１８Ａ…マトリックス、１８Ｂ…マトリックス、１９…小突起部。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a carbonaceous material having an oxidation-resistant protective layer that is not substantially oxidized at least at 800 ° C. in the atmosphere, a method for producing the carbonaceous material, and uses of the composite material.
[0002]
[Prior art]
Today, with the rapid advancement of technological innovation, the emergence of materials that do not substantially oxidize in the atmosphere at high temperatures of at least 800 ° C, preferably 1000 ° C or higher, Especially in the field of space development such as kiln tools used in the presence of oxygen, ceramic condenser setters, and production of protective glass for plasma TVs known as wall-mounted large displays. Has been. Of course, for use in such fields, high strength at high temperatures (high thermal shock resistance) and high reliability as materials (toughness, impact resistance, wear resistance), environmental resistance (corrosion resistance, oxidation resistance) Needless to say, in addition to energy saving and radiation resistance, light weight is required from the viewpoint of energy saving and workability.
[0003]
Among these fields, in some fields, silicon nitride and silicon carbide materials having excellent heat resistance and high strength have been used in the past, but they have the disadvantage of being brittle as an inherent property. It was extremely fragile against small scratches and did not have sufficient strength against thermal and mechanical impacts.
[0004]
Further, as a means for overcoming the disadvantages of ceramics, ceramic composite materials (CMC) in which continuous ceramic fibers are combined have been developed, and application development in some fields has been carried out. In such attempts, a ceramic bundle having a diameter of about 10 μm is usually bundled with several hundred to several thousand pieces to form a fiber bundle (yarn), and the fiber bundle is arranged in a two-dimensional or three-dimensional direction. By arranging them into a unidirectional sheet (UD sheet) or various cloths, or by laminating the above sheets or cloths, a preform with a predetermined shape (fiber preform) is formed. In addition, a matrix is formed by forming a matrix by a CVI method (chemical vapor phase impregnation method) or an inorganic polymer impregnation firing method, or by filling a ceramic powder inside the preform by a casting method and firing it. A ceramic fiber composite material (CMC) in which fibers are combined in a ceramic matrix has been developed.
[0005]
Specific examples of such CMC include C / C composites in which a matrix made of carbon is formed between carbon fibers arranged in a two-dimensional or three-dimensional direction, and Si is formed on a molded body containing SiC fibers and SiC particles. An SiC fiber reinforced Si-SiC composite formed by impregnation is known. However, such a SiC fiber reinforced Si-SiC composite is excellent in oxidation resistance, creep resistance, spalling resistance, etc., but SiC fiber is inferior in lubricity with Si-SiC etc. Because the pulling effect between fibers is small, it is inferior in toughness compared to C / C composites, so impact resistance is low, and because some carbon fibers are used, it easily burns in the presence of oxygen There is a problem of end up.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described conventional problems. The object of the present invention is high strength at high temperatures (high thermal shock resistance) and high reliability as materials (toughness, impact resistance, resistance to heat). Abrasion resistance), environmental resistance (corrosion resistance, oxidation resistance, radiation resistance), etc., as well as light weight from the viewpoint of energy saving and workability, and at least 800 ° C. in air, preferably 1000 ° C. It is an object of the present invention to provide a novel carbonaceous material that is not substantially oxidized even at the above high temperature, and a method for producing the carbonaceous material.
[0007]
[Means for Solving the Problems]
As a result of various investigations in view of the present situation as described above, the present inventors have achieved the above object with a carbonaceous material having an oxidation-resistant protective layer that is not substantially oxidized at least at 800 ° C. in the atmosphere. And the present invention has been completed. Furthermore, at least a boron-containing layer on the surface of the carbonaceous material and, if desired, a layer made of glass and / or ceramics is protected against oxidation so as not to be substantially oxidized at least at 800 ° C. in the atmosphere. It has been found that the above object can be achieved by a method for producing a carbonaceous material having an oxidation-resistant protective layer that is not substantially oxidized at least at 800 ° C. in the atmosphere, characterized in that it is formed as a layer. Thus, the present invention has been completed.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The carbonaceous material which concerns on this invention uses the raw material which consists mainly of carbon fiber as the base material. As a carbonaceous material used in the present invention, firstly, carbon fibers are mentioned. Such carbon fibers can be used regardless of the production method and the raw materials used. In actual use, carbon fiber is formed into a predetermined shape using a binder or the like and used. From the viewpoint of durability, the following C / C composite is preferable. Further, a composite material obtained by impregnating Si with a C / C composite is also included in the carbonaceous material referred to in the present invention. As the composite material impregnated with Si, Si-SiC composite materials and SiC composite materials defined below and described in detail are preferably used. Here, in the present specification, the carbonaceous material includes not only the carbon fiber itself but also a C / C composite contained in the carbon fiber in a broad sense. In addition, the carbonaceous material containing both a Si-SiC composite material and a SiC composite material, which is a carbonaceous material with a specific processing obtained by impregnating a predetermined amount of metallic silicon into this C / C composite, is included in the carbonaceous material. . The properties and manufacturing methods of these will be described in detail below. In order to avoid naming confusion, in the following description of the present specification, the carbonaceous material is a term including C / C composites, Si-SiC based composite materials, and SiC based composite materials. use. Therefore, in the present invention, not only the narrowly defined carbon fibers but also the above-mentioned composite materials can be used as the base material.
[0009]
In this specification, the C / C composite is a powdery binder that acts as a matrix for a bundle of carbon fibers, and includes a pitch and coke that become free carbon after firing to a bundle of carbon fibers. Further, if necessary, a carbon fiber bundle is prepared by adding a phenol resin powder or the like, and a flexible film made of a plastic such as a thermoplastic resin is formed around the carbon fiber bundle. As a pre-formed yarn. This preformed yarn is formed into a sheet or woven fabric by the method described in JP-A-2-80639, and after a necessary amount is laminated, a molded product obtained by molding with a hot press, or this A fired body obtained by firing a molded body. That is, in the present invention, the C / C composite is composed of carbon fibers and carbons other than carbon fibers, and the carbon fibers constitute a laminated structure composed of a coal layer fiber bundle composed of a specific number of carbon fibers. Carbon other than means a composite material comprising a specific laminated structure and a matrix structure having a structure in which voids between the laminated structure and the laminated structure are filled with a matrix.
[0010]
As a C / C composite used as a basic material, a carbon fiber having a diameter of around 10 μm is usually bundled from several hundred to several tens of thousands to form a fiber bundle (yarn), and this fiber bundle is covered with a thermoplastic resin. A flexible thread-like intermediate material prepared as described above is obtained, and this is made into a sheet by the method described in JP-A-2-80639, and this sheet is arranged in a two-dimensional or three-dimensional direction. By forming a directional sheet (UD sheet) or various cloths, or by laminating the above sheets or cloths, a preform having a predetermined shape (fiber preform) is formed, and the outer periphery of the fiber bundle of the preform is formed. What is necessary is just to use what formed the film of the thermoplastic resin etc. which consist of the formed organic substance by baking, and carbonized and removed the said film | membrane. In this specification, the description of JP-A-2-80639 is cited for reference. In the C / C composite used in the present invention, the carbon component other than the carbon fiber in the yarn is preferably a carbon powder, and particularly preferably a graphitized carbon powder.
[0011]
In the present invention, the Si—SiC based composite material is composed of 55 wt% to 75 wt% carbon, 1 wt% to 10 wt% silicon, and 10 wt% to 50 wt% silicon carbide, A yarn assembly in which yarns containing at least a bundle of carbon fibers and a carbon component other than carbon fibers are three-dimensionally combined while being oriented in the layer direction and integrated so as not to separate from each other, and this yarn assembly A matrix composed of a Si-SiC material filled between adjacent yarns, and a dynamic friction coefficient of 0.05 to 0.6 and a porosity controlled to 0.5% to 10% And a composite material. This material can be manufactured by the method disclosed in Japanese Patent Application No. 10-267402 filed on September 4, 1998. Therefore, the content of Japanese Patent Application No. 10-267402 is cited here.
[0012]
Here, the Si-SiC-based material includes a number of different phases ranging from a silicon phase consisting of silicon remaining in an unreacted state to almost pure silicon carbide, typically silicon. The silicon carbide phase includes a SiC coexisting phase in which the silicon content is changed in a gradient manner. Therefore, the Si—SiC-based material is a generic name for materials that are contained within the range of 0 mol% to 50 mol% as the carbon concentration in the Si—SiC series. In the Si—SiC based composite material according to the present invention, the matrix portion is formed of the Si—SiC based material.
[0013]
The Si-SiC composite material preferably has a matrix having a gradient composition in which the content ratio of silicon increases as the distance from the surface of the yarn increases. In this Si-SiC composite material, the yarn assembly made of carbon fibers is preferably composed of a plurality of yarn arrays, and each yarn array is configured by bundling a specific number of carbon fibers. The yarns are formed by two-dimensionally arranging the yarns substantially parallel to each other, and a yarn assembly is formed by stacking the yarn arrays. Thus, the Si—SiC based composite material has a laminated structure in which a plurality of layers of yarn arrays are laminated in a specific direction.
[0014]
1 is a schematic perspective view for explaining the concept of a yarn assembly, FIG. 2 (a) is a sectional view taken along the line IIa-IIa in FIG. 1, and FIG. 2 (b) is a sectional view taken along line IIb-IIb in FIG. It is line sectional drawing. The skeleton of the Si—SiC composite material 7 is constituted by a yarn assembly 6. The yarn assembly 6 is formed by stacking yarn arrays 1A, 1B, 1C, 1D, 1E, and 1F in the vertical direction. In each yarn array, each yarn 3 is arranged two-dimensionally, and the longitudinal direction of each yarn is substantially parallel. The longitudinal direction of each yarn in each yarn array adjacent to each other in the vertical direction is orthogonal. That is, the longitudinal directions of the yarns 2A of the yarn arrays 1A, 1C, and 1E are parallel to each other and orthogonal to the longitudinal direction of the yarns 2B of the yarn arrays 1B, 1D, and 1F. Each yarn is composed of a fiber bundle 3 composed of carbon fibers and carbon components other than carbon fibers. By stacking the yarn arrays, a three-dimensional lattice-shaped yarn assembly 6 is formed. Each yarn is crushed during a pressure forming process as described later, and has a substantially elliptical shape.
[0015]
In each yarn array 1A, 1C, 1E, a gap between adjacent yarns is filled with a matrix 8A, and each matrix 8A extends parallel to the surface of the yarn 2A. In each yarn array 1B, 1D, 1F, the gap between adjacent yarns is filled with a matrix 8B, and each matrix 8B extends parallel to the surface of the yarn 2B.
In this example, the matrixes 8A and 8B are respectively composed of silicon carbide phases 4A and 4B covering the surface of each yarn, and Si-SiC-based material phases 5A and 5B having a lower carbon content than the silicon carbide phases 4A and 4B. It is made up of. The silicon carbide phase may partially contain silicon. In this example, silicon carbide phases 4A and 4B are also generated between yarns 2A and 2B adjacent in the vertical direction.
[0016]
Each matrix 8A and 8B is elongated along the surface of the yarn, and preferably extends linearly, and each matrix 8A and 8B is orthogonal to each other. The matrix 8A in the yarn arrays 1A, 1C, and 1E and the matrix 8B in the yarn arrays 1B, 1D, and 1F orthogonal thereto are continuous at the gap portions between the yarns 2A and 2B, respectively. As a result, the matrices 8A and 8B form a three-dimensional lattice as a whole.
[0017]
In the present invention, the SiC-based composite material is composed of silicon carbide, carbon fiber, and a carbon component other than carbon fiber, and is a SiC-C / C having a structure including a skeleton part and a matrix formed around the skeleton part. A composite composite material in which at least 50% of silicon carbide is β-type, the skeleton is formed of carbon fibers and carbon components other than carbon fibers, and silicon carbide is present in a part of the skeleton. The matrix may be formed of silicon carbide, the matrix and the skeleton portion may be formed integrally, and the composite material may have a porosity of 0.5% to 5% and a double shape. A composite material having an average pore size distribution.
[0018]
Therefore, this SiC composite material uses a C / C composite in which each carbon fiber is composed of a carbon fiber bundle as a skeleton part. Therefore, even if SiC is formed in a part of each carbon fiber, Since the structure as a carbon fiber is maintained without being broken as the fiber, the carbon fiber is not shortened by silicon carbide, so the mechanical strength of the C / C composite as a raw material is high. It has a great feature of being almost retained or increased by silicon carbide. Moreover, it has a composite structure in which a matrix made of a SiC-based material is formed between adjacent yarns in the yarn assembly. In this respect, it differs from the Si-SiC composite material. This material can be manufactured by the method disclosed in Japanese Patent Application No. 11-31979, filed on Feb. 9, 1999. Therefore, the content of Japanese Patent Application No. 11-31979 is cited here.
[0019]
In the present invention, the SiC-based material refers to a material containing silicon carbide having a different degree of bonding with carbon, and this SiC-based material refers to a material manufactured as follows. In the present invention, the C / C composite is impregnated with metallic silicon. At this time, the metallic silicon is a carbon atom constituting the carbon fiber in the composite and / or a free carbon atom remaining on the surface of the carbon fiber. Partly carbonized, so that partly carbonized silicon is formed between the outermost surface of the C / C composite and between the yarn made of carbon fiber and the yarn, and thus the above-mentioned yarn and yarn A matrix made of silicon carbide is formed between the two.
[0020]
In this matrix, a very small amount of silicon and carbon are bonded, but it may contain several different phases from a silicon carbide phase to a pure silicon carbide crystal phase. However, this matrix contains only metallic silicon below the detection limit (0.3 wt%) by X-rays. That is, this matrix is typically composed of a silicon carbide phase, but the silicon carbide phase can include a SiC-based phase in which the silicon content is changed in a gradient manner. Accordingly, the SiC-based material is a generic name for materials that are included in such a SiC series within a range of at least 0.01 mol% to 50 mol% as the carbon concentration. In order to control the carbon concentration to less than 0.01 mol%, a strict measurement of the amount of metallic silicon to be added is required in relation to the amount of free carbon in the C / C composite. Since temperature management in the process becomes complicated, it is not substantial. Therefore, theoretically, it is possible to control the carbon concentration to about 0.001 mol%.
[0021]
This Si-based composite material will be further described with reference to the drawings. The skeleton portion of this SiC-based composite material is basically the same as that shown in FIG. 1 is a cross-sectional view of the SiC composite material according to the present invention taken along the line IIa-IIa in FIG. 1. FIG. 3A is a cross-sectional view taken along the line IIb-IIb in FIG. 3 (b).
Similar to the skeleton of the Si-SiC composite material 7, the skeleton of the SiC composite material 17 is constituted by the yarn assembly 16. The yarn assembly 16 is formed by stacking yarn arrays 11A, 11B, 11C, 11D, 11E, and 11F in the vertical direction. In each yarn array, each yarn 13 is two-dimensionally arranged, and the longitudinal direction of each yarn is substantially parallel. The longitudinal direction of each yarn in each yarn array adjacent to each other in the vertical direction is orthogonal. That is, the longitudinal directions of the yarns 12A of the yarn arrays 11A, 11C, and 11E are parallel to each other and orthogonal to the longitudinal direction of the yarns 12B of the yarn arrays 11B, 11D, and 11F. Each yarn is composed of a fiber bundle 13 composed of carbon fibers and carbon components other than carbon fibers. By stacking the yarn arrays, a three-dimensional lattice-shaped yarn assembly 16 is formed. Each yarn is crushed during a pressure forming process as will be described later, and is somewhat oval.
[0022]
In each yarn array 11A, 11C, 11E, a gap between adjacent yarns is filled with a matrix 18A, and each matrix 18A extends along the surface of the yarn 12A in parallel therewith. In each yarn array 11B, 11D, and 11F, the space | interval of each adjacent yarn is filled with the matrix 18B, and each matrix 18B is extended in parallel with it along the surface of the yarn 12B. As shown in FIGS. 3 (a) and 3 (b), the matrices 18A and 18B are each composed of a silicon carbide phase 14 covering the surface of each yarn. A part of the silicon carbide phase may protrude from the surface as the small protrusion 19 or may protrude from the carbon fiber layer inside the composite member. Inside such a small protrusion, pores (void: 15) having a median diameter of about 100 μm are formed. The small protrusions 19 are mostly formed along the trace of a matrix made of a carbon component other than the carbon fiber of the raw material C / C composite, so that the distance between the yarns and the yarns and / or the yarn array The density of the small protrusions 19 per unit area can be adjusted by appropriately selecting the distance from the yarn array. Silicon carbide phase 14 may also be formed between adjacent yarns 12A and 12B.
[0023]
Each matrix 18A and 18B is elongated along the surface of the yarn, preferably extending linearly, and each matrix 18A and 18B is orthogonal to each other. The matrix 18A in the yarn arrays 11A, 11C, and 11E and the matrix 18B in the yarn arrays 11B, 11D, and 11F orthogonal to the yarn arrays 11A, 11C, and 11E are continuous at the gap portions between the yarns 12A and 12B, respectively. As a result, the matrices 18A and 18B form a three-dimensional lattice as a whole.
[0024]
Next, a carbonaceous material having an oxidation-resistant protective layer that is not substantially oxidized at least at 800 ° C. in the atmosphere according to the present invention will be described. This carbonaceous material according to the present invention is formed on the carbonaceous material having a predetermined shape as described above to form an oxidation-resistant protective film that is not substantially oxidized even in the air at a high temperature exceeding 800 ° C. It refers to the material that is being used. Here, “substantially not oxidized” means that the increase or decrease in weight is 0.5% or less when the sample is held in the atmosphere at a predetermined high temperature, for example, 800 ° C. for at least 24 hours. Say. The oxidation-resistant protective layer that is not substantially oxidized at least at 800 ° C. in the atmosphere refers to a layer composed of at least one layer selected from a boron-containing layer, glass, and ceramics. Examples of a plurality of oxidation-resistant protective layers include a boron-containing layer and a glass layer, a boron-containing layer and a ceramic layer, a boron-containing layer, and a ceramic and glass layer. Of course, it goes without saying that the ceramic layer includes those formed from a plurality of different ceramic layers. Needless to say, the order of laminating these layers may be appropriately selected depending on the desired performance, usage conditions, and the like. Of course, layers other than those described above may be provided between the above layers.
[0025]
Note that it is necessary that at least the boron-containing layer is formed. Preferably, the boron-containing layer is usually formed directly on the layer closer to the substrate surface, preferably the innermost layer, that is, the surface of the carbonaceous material having a predetermined shape. With this configuration, even if peeling or cracking occurs due to something in the oxidation-resistant protective layer formed on the outermost surface, the carbonaceous material is protected by the oxidation-resistant characteristics of the boron-containing layer. Because it will be. Of course, if desired, a primer layer, a layer made of ceramics, or the like may be provided between the boron-containing layer and the surface of the carbonaceous material as the substrate.
[0026]
A boron-containing layer may be provided in the outermost layer according to the use mode of the carbonaceous material according to the present invention. For example, when boron carbide is used as the outermost layer, when exposed to an oxidizing atmosphere at 400 ° C. or higher, boron carbide is oxidized to form molten boron oxide, which is a carbonaceous material. The substrate surface can be protected. Of course, when exposed to an oxidizing atmosphere at 400 ° C. or higher for a long time, the boron carbide layer becomes all boron oxide, and the substrate surface is exposed, and the substrate surface is easily oxidized. Therefore, in an application where the surface is exposed to an oxidizing atmosphere of 400 ° C. or higher for a long period of time, it is preferable to use the outermost surface in which a layer made of glass or a layer made of ceramics is formed.
[0027]
The thickness of the boron-containing layer is 10 μm to 500 μm, preferably 50 μm to 200 μm. This is because if it is less than 10 μm, it is difficult to form a boron-containing layer as a homogeneous continuous layer. Further, even if the boron carbide layer is formed to exceed 500 μm, improvement in oxidation resistance cannot be expected, and the boron-containing material is expensive, which is not economical. The boron-containing layer can also be formed by directly applying to the material surface, and can also be formed by thermal spraying or the CDV method. It can be formed by spraying a boron-containing material on the surface of a carbonaceous material together with an inert gas such as argon. The boron-containing material used for forming the boron-containing layer includes materials having high oxidation resistance such as borate glass, borosilicate glass, boron nitride, and boron carbide. Among these, boron carbide is preferable from the viewpoint of oxidation resistance.
[0028]
An oxidation-resistant protective layer made of glass is preferable because it improves oxidation resistance at high temperatures. Examples of the glass include high melting point glass, for example, Pyrex glass (registered trademark) manufactured by Corning. This layer may be formed by thermal spraying in the same manner as the boron-containing layer. The thickness of this layer is 10 μm to 500 μm, the same as the thickness of the boron-containing layer. If it is less than 10 μm, it is not preferable because sufficient oxidation resistance may not be exhibited when exposed to a high temperature exceeding 800 ° C., for example, a high temperature exceeding 1000 ° C. Even if this glass layer is formed to exceed 500 μm, the improvement in oxidation resistance can not be expected, and the advantage of the light weight of the carbonaceous material used as the folded base may be impaired. It is not preferable.
[0029]
The layer made of ceramic means a layer formed from an oxide, carbide, nitride, or mixture thereof as a main component of Group IIIa, Group IIIb, Group IVa to Group VIa elements. More preferably, the main component is a material selected from oxides such as alumina, silica, titania and zirconia, carbides such as silicon, titanium and zirconium, and nitrides of these metals. In addition, when providing the layer which consists of ceramics, since the elasticity modulus is high compared with glass, even if a thermal expansion coefficient is the same, a high thermal stress is easy to generate | occur | produce. In order to relieve thermal stress, it is preferable to form a layer made of ceramics with microcracks. The microcrack itself permeates oxygen, but by using the boron-containing layer as an inner layer in combination, the boron oxide generated by oxidation is retained in the microstructure of the microcrack, and as a result, oxygen It is possible to prevent entry.
[0030]
The layer made of ceramics with microcracks is a layer made of alumina and / or zirconia. Layers of these oxides are boron-containing layers, for example, when boron carbide is exposed to oxidizing conditions, boron oxide is generated, and the generated boron oxide is not adsorbed by carbon and flows out of the system. Therefore, the function of preventing the use as a protective layer is prevented. The layer made of alumina and / or zirconia forms a sponge-like structure in which countless fine pores are formed in the gap between the carbon fibers of the carbonaceous material that is the substrate, and this structure has The action of adsorbing boron oxide generated by oxidation to form a so-called oxidation-resistant glass layer made of boron oxide, alumina, and / or zirconia, thereby protecting the surface of the substrate made of carbon fiber. Is shown. A layer made of glass or ceramic may be further formed on such a sponge-like oxide layer. Thereby, further oxidation resistance is exhibited. The ratio of the thermal expansion coefficient between layers such as a boron-containing layer and a ceramic layer and / or a glass layer is preferably 1: 2 or less from the viewpoint of preventing the occurrence of thermal stress. .
[0031]
A layer made of glaze may be formed as the layer made of ceramics. Although the layer made of glaze is slightly lower than the oxidation-resistant protective layer made of glass, it is preferable because oxidation resistance at a high temperature exceeding 800 ° C. can be ensured. As the glaze, glass glaze and smoked glaze are preferably used. As the glass glaze, for example, GL-400 and GL-700 series glazes made by Ikebukuro Kaisha are preferably used. As the smoked glaze, cocoons usually used for glazing treatment such as iron plates are preferably used. That is, silicon oxide is 45 to 55%, boron oxide is 10 to 20%, aluminum oxide is 5 to 10%, alkali oxide is 15 to 30%, alkaline earth oxide is 0 to 10%, and other oxides are 5%. A glaze consisting of 15% is preferably used. According to a conventional method, this material may be frit-coated, the coating is heated to about 1000 ° C. for about 10 minutes in the atmosphere, and so-called self-glazing is performed to form an oxidation-resistant protective layer made of glaze. The thickness of this layer may also be the same thickness as the boron-containing layer, that is, about 10 μm to 500 μm. If it is less than 10 μm, it is not preferable because sufficient oxidation resistance may not be exhibited when exposed to a high temperature of about 800 ° C. for a long time. Even if this saddle layer is formed over 500 μm, the improvement in oxidation resistance cannot be expected, and the lightness that is an advantage of the carbonaceous material used as the corner substrate may be impaired. Since it is not, it is not preferable.
[0032]
The following is a method for producing a composite material according to the present invention. At least a boron-containing layer on the surface of a carbonaceous material, and further, a layer made of glass and / or ceramics as desired, is at least 800 ° C. in the atmosphere. About the manufacturing method of the carbonaceous material which has an oxidation-resistant protective layer which consists of forming as an oxidation-resistant protective layer which is not substantially oxidized and which is not substantially oxidized at least 800 degreeC in air | atmosphere The details will be described. A carbonaceous material as a substrate is processed into a desired shape according to the end use, and a material selected so that a desired oxidation-resistant film is formed on the surface of this material is applied, sprayed, or CVD is appropriately performed. What is necessary is just to select and form. For example, when the boron-containing layer is formed by thermal spraying, the boron-containing material is sprayed together with an inert gas such as argon. There are no particular limitations on the thermal spraying conditions, and it is usually sufficient to follow the conditions employed in the metal processing field. Thermal spraying may be performed for each surface of the predetermined shape retaining material, or all surfaces may be performed at the same time. However, in order to ensure uniformity and to limit the equipment for thermal spraying, it is performed for each surface or predetermined. It is preferable to carry out the process while rotating the shape-retaining material at a constant speed. As described above, the thickness of the sprayed boron carbide is usually about 10 μm to 500 μm.
[0033]
For example, after forming the first protective layer on the surface of the carbonaceous material by applying a boron-containing material made of a boron-containing layer, a layer made of glass and / or ceramics on the protective layer thus formed A layer consisting of is formed. In some cases, an eaves layer may be formed. The glass layer is formed by spraying a fine powder such as Pyrex glass in the same manner as boron carbide. The thickness of this layer is about 10 μm to 500 μm, which is the same as the thickness of the boron-containing layer. The soot layer may be formed by frit-coating the above-described soot material according to a conventional method, heating the coat to about 1000 ° C. in the atmosphere for about 10 minutes, and performing so-called self-glazing to form the soot layer. As described above, the order of forming the oxidation-resistant protective film may be selected according to design performance, purpose of use, and the like. As for the formation method, a known method such as coating, impregnation, thermal spraying, and CVD method may be appropriately selected and combined in consideration of the stacking order, material characteristics, and the like.
[0034]
A ceramic layer containing micro cracks made of alumina and / or zirconia may be provided between the glass layer or the soot layer and the boron-containing layer. This layer may also be sprayed. As described above, the ceramic layer containing the microcracks means that when the boron-containing layer is exposed to oxidizing conditions, boron oxide is generated, and the generated boron oxide is not adsorbed by carbon, and thus flows out of the system. Thus, the function of preventing the use as a protective layer is prevented.
[0035]
The carbonaceous material having an oxidation-resistant protective layer that is not substantially oxidized at least at 800 ° C. in the atmosphere according to the present invention thus manufactured is used as a substrate, and the carbonaceous material has high impact resistance. Because of its low thermal expansion coefficient and light weight, it retains its properties as it is, and a robust oxidation-resistant protective layer is formed on its surface. The generation of fine powder due to mechanical action is extremely small. Furthermore, since the boron-containing layer having high thermal shock resistance is formed as at least one layer of the oxidation-resistant protective layer, the thermal shock resistance is high. Also, the flatness of the surface is extremely high. Therefore, it can be used very suitably as a member for a setter, a material for various kiln tools, and the like when firing a glass panel for a plasma television.
[0036]
【Example】
Hereinafter, specific embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded. The measurement of oxidation resistance in the examples was performed by the following method.
[0037]
(Oxidation resistance preliminary test)
After holding the test sample in the air heated to 800 ° C. for 5 minutes, the weight is measured and compared with the weight before the test. ₂ Was determined by the following equation.
W ₂ = (W ₀ -W ₁ ) / W ₀ × 100
However, W in the formula ₀ Is the weight before the oxidation resistance test, W ₁ Is the weight after the oxidation resistance test, W ₂ Represents the weight loss rate.
[0038]
(Oxidation resistance measurement test)
After holding the test sample in the atmosphere heated to 800 ° C. for a predetermined time, the weight is measured, and the weight change rate W is compared with the weight before the test. _{2 '} Was determined by the following equation.
W _{2 '} = (W ₀ -W ₁ ) / W ₀ × 100
However, W in the formula ₀ Is the weight before the oxidation resistance test, W ₁ Is the weight after the oxidation resistance test, W _{2 '} Represents the rate of increase / decrease in weight (decreases are identified by a minus sign in front of the number).
[0039]
(Oxidation resistance test under adverse environment)
The test sample was held in a chamber at a room temperature of 1000 ° C. in an argon atmosphere containing 3% water vapor for 50 hours, and then the weight was measured. _{2 '} Was determined by the following equation. Further, the appearance of each sample was inspected with the naked eye and under a microscope to inspect for the occurrence of cracks.
W _{2 '} = (W ₀ -W ₁ ) / W ₀ × 100
However, W in the formula ₀ Is the weight before the oxidation resistance test, W ₁ Is the weight after the oxidation resistance test, W _{2 '} Represents the rate of increase / decrease in weight (decreases are identified by a minus sign in front of the number).
[0040]
(Production example)
(1) Manufacture of Si-SiC composite materials
Carbon fiber is aligned in one direction and impregnated with phenol resin, and about 10,000 carbon long fibers having a diameter of 10 μm are bundled to obtain a fiber bundle (yarn). Sheet) was prepared and arranged as shown in FIG. 1 to obtain a prepreg sheet laminate, and a carbon-based adhesive was applied to the prepreg sheet laminate to fix the yarns together. After fixing, the fixed body is released from the mold, the released prepreg sheet laminate is put in an oven, the impregnated phenol resin is cured at 180 ° C. and normal pressure, and then in a nitrogen atmosphere at 2000 ° C. Baked. Next, Si powder having a purity of 99.9% and an average particle diameter of 1 mm was added to the obtained carbon fiber reinforced carbon composite material, and this was placed in a firing furnace having a furnace temperature of 1300 ° C. and a furnace pressure of 1 hPa. It was held for 4 hours while flowing argon gas at a rate of 20 NL per minute. Next, while maintaining the furnace pressure, the furnace temperature was raised to 1600 ° C. and impregnated with Si. Thus, an Si—SiC composite material composed of Si, Si—C, and carbon fibers was obtained. The obtained fired body was cut and peripherally processed to produce a test piece having a size of 9 mm × 9 mm × 9 mm.
[0041]
(2) Formation of oxidation-resistant protective layer (1)
The test piece of 9 mm × 9 mm × 9 mm obtained in (1) above was set on a jig, and while rotating the test piece at a constant speed, a purity of 99.5% and an average particle size of 25 μm or less of boron carbide The powder (manufactured by ESK) was sprayed with argon plasma to preliminarily form a boron carbide layer having a thickness of about 50 μm on the surface. Furthermore, after changing to another jig, the entire surface of the test piece was sprayed. This test piece was subjected to the above oxidation resistance preliminary test. For comparison, a Si-SiC composite material test piece of the same size and an ISO 63 oxidation-resistant carbon test piece were similarly subjected to a preliminary test. As a result of the preliminary test, no substantial weight reduction was observed in the test piece on which the oxidation-resistant protective layer made of boron carbide was formed. However, a weight reduction of about 33% was observed in the Si-SiC composite specimen, and a weight reduction of about 95% was observed in the oxidation-resistant carbon specimen of ISO63.
[0042]
(3) Formation of oxidation-resistant protective layer (2)
Therefore, boron carbide is thermally sprayed on the Si-SiC composite material having a size of 9 mm × 9 mm × 9 mm obtained in the above (1), and a boron carbide oxidation-resistant protective layer having a boron carbide layer thickness of 50 μm is provided. A composite member was manufactured. This was further sprayed with alumina to produce a carbonaceous material having an oxidation-resistant protective layer of alumina having a thickness of 50 μm. This test piece was subjected to the above oxidation resistance measurement test. The test piece of the carbonaceous material according to the present invention obtained in the above (2) was also subjected to the same test. As a comparative example, a test piece of Si-SiC composite material was also subjected to the same test. The result is shown in FIG. In the case of the specimen of the Si—SiC composite material, all of the free carbon burned after 1 hour from the start of the test. In the case of only the boron carbide layer, no particular change was observed until 60 hours of the test, but after 80 hours, all of the free carbon burned. In the case of this test piece, the test piece was fixed to the alumina jig holding the test piece. On the other hand, no further change was observed in the weight of the thermally sprayed alumina even after 100 hours. In addition, it did not adhere to the jig made of alumina holding the test piece.
[0043]
(4) Formation of oxidation-resistant protective layer (3)
In the formation (2) of the oxidation-resistant protective layer of (3) above, a 1: 1 mixture of alumina and zirconia is sprayed instead of alumina, so that the thickness of the oxidation-resistant protective layer is 50 μm thick. A carbonaceous material in which an oxidation-resistant protective layer made of a 1: 1 mixture of 50 μm thick alumina and zirconia was formed on the boron carbide layer was produced. This specimen was subjected to the above-described oxidation resistance measurement test. The test piece of the carbonaceous material according to the present invention obtained in the above (2) was also subjected to the same test. As a comparative example, a test piece of Si-SiC composite material was also subjected to the same test. The result is shown in FIG. The result was almost the same as FIG. That is, in the case of the test piece of Si-SiC composite material, all of the free carbon burned after 1 hour from the start of the test. In the case of only the boron carbide layer, no particular change was observed until 60 hours of the test, but most of the free carbon burned after 80 hours. On the other hand, the thermal spraying of a 1: 1 mixture of alumina and zirconia showed little change in weight even after 80 hours.
[0044]
Formation of the above-mentioned oxidation resistant protective layer (1) to (3) The materials according to the present invention obtained in (1) to (3) and, as a comparative example, an oxidation resistance test under a bad environment using a Si-SiC composite material. Provided. That is, the test sample was held in a chamber at room temperature of 1000 ° C. in an argon atmosphere containing 3% water vapor for 50 hours, and then the weight was measured. _{2 '} Was determined by the above formula. Further, the appearance of each sample was inspected with the naked eye and under a microscope to inspect for the occurrence of cracks. The test results are shown in Table 1 below.
[0045]
[Table 1]

[0046]
As is clear from the above table, B _Four When an oxidation-resistant protective layer composed of C (boron carbide) / alumina is formed, no substantial change is observed in mass and appearance even when used under conditions of exposure to high temperatures of 800 ° C or higher for a long time. It was. But B _Four In the case of a protective layer composed of C (boron carbide) / alumina / zirconia, the change in weight was very small, but cracks were generated on the surface. However, considering the results shown in FIG. 5 together, it was determined that the product could be used sufficiently in applications such as those used under dry conditions. Of course, in the case of an oxidation-resistant protective layer composed only of boron carbide, even if boron oxide is generated as a result of oxidation, the wettability with the carbon fiber is not good, so it will be washed away without being retained. Therefore, it is apparent that the use under the condition of being exposed to a high temperature of 800 ° C. or higher in the atmosphere is substantially impossible. As described above, even if boron carbide is oxidized to form boron oxide by providing a microcrack-containing protective layer made of alumina or alumina / zirconia on boron carbide, it is retained in this protective layer. Therefore, it is considered that the oxidation resistance is remarkably improved.
[0047]
(5) Formation of oxidation-resistant protective layer (4)
(3) Formation of oxidation-resistant protective layer (2) In the step (2), Pyrex (registered trademark) glass is sprayed instead of alumina, and Pyrex glass having a thickness of 50 μm is substituted for the oxidation-resistant protective layer of alumina having a thickness of 50 μm. The composite member which formed the oxidation-resistant protective layer which consists of a layer on the boron carbide layer was manufactured. When this test piece was subjected to the above-described oxidation resistance measurement test, almost no change in weight was observed even after 80 hours.
[0048]
【The invention's effect】
As is clear from the above test results, in the case of the carbonaceous material on which the oxidation-resistant protective layer according to the present invention is formed, high strength at high temperature (high thermal shock resistance) and high reliability as a material (toughness) Needless to say, it is excellent in impact resistance, wear resistance), environmental resistance (corrosion resistance, oxidation resistance, radiation resistance) and the like. In addition, C / C composites, or Si-SiC composites manufactured by impregnating metallic silicon into the composites, or SiC composites are used as the substrate. In addition, it is needless to say that the material is extremely excellent as a light-weight field where a high workability is required, as an instrument such as various kiln tools, for example, a setter used for manufacturing a plasma display panel. .
[Brief description of the drawings]
FIG. 1 is a perspective view schematically showing the structure of a yarn assembly used as a base of a carbonaceous material having an oxidation-resistant protective layer according to the present invention and constituting the basic structure of a SiC-based composite material and a SiC-based composite material. FIG.
2A is a cross-sectional view of a Si-SiC composite material cut along line IIa-IIa in FIG. 1, and FIG. 2B is a cross-sectional view taken along line IIb-IIb in FIG. FIG.
3A is a cross-sectional view of a SiC-based composite material cut along line IIa-IIa in FIG. 1, and FIG. 3B is a cross-sectional view taken along line IIb-IIb in FIG. FIG.
FIG. 4 is a graph showing the results of an oxidation resistance measurement test of a carbonaceous material having a protective layer made of boron carbide / alumina, which is an embodiment of the carbonaceous material having an oxidation resistant protective layer according to the present invention.
FIG. 5 is a graph showing the results of an oxidation resistance measurement test of a carbonaceous material having a protective layer made of boron carbide / alumina / zirconia, which is another embodiment of the carbonaceous material having an oxidation resistant protective layer according to the present invention. It is.
[Explanation of symbols]
1A, 1B, 1C, 1D, 1E and 1F ... yarn array, 2A ... yarn, 2B ... yarn, 3 ... fiber bundle (yarn), 4A ... silicon carbide phase, 4B ... silicon carbide phase, 4C ... silicon carbide phase, 5A ... Si-SiC-based material phase, 5B ... Si-SiC-based material phase, 5C ... Si-SiC-based material phase, 6 ... yarn aggregate, 7 ... fiber composite material, 8A ... matrix, 8B ... matrix, 11A, 11B , 11C, 11D, 11E and 11F ... yarn array, 12A ... yarn, 12B ... yarn, 13 ... fiber bundle (yarn), 14 ... silicon carbide phase, 15 ... void, 16 ... yarn assembly, 17 ... fiber composite material , 18A ... matrix, 18B ... matrix, 19 ... small protrusion.

Claims (8)

A material composed of a Si-SiC-based composite material and a plurality of oxidation-resistant protective layers formed on the carbonaceous material, and at least one of the plurality of oxidation-resistant protective layers is mainly composed of boron carbide. Including a boron-containing layer having a thickness of 10 μm to 500 μm , and on the boron-containing layer, a layer made of a ceramic selected from a Pyrex (registered trademark) glass layer or alumina, or an alumina / zirconia mixture , An oxidation-resistant protective layer having a thickness of 10 μm to 500 μm, and by forming this oxidation-resistant protective layer, when the carbonaceous material is kept in the atmosphere at least at 800 ° C. for 24 hours, the increase or decrease in weight is 0.5% or less The carbonaceous material characterized by being.   The carbonaceous material according to claim 1, wherein the boron-containing layer is formed by thermal spraying.   2. The carbonaceous material according to claim 1, wherein the glass layer is formed by a thermal spraying method or self-glazing.   The carbonaceous material according to claim 1, wherein the ceramic layer is formed by thermal spraying or self-glazing.   The carbonaceous material according to claim 4, wherein the ceramic layer forms microcracks. 6. The carbonaceous material according to claim 5 , wherein the ratio of the thermal expansion coefficient of the boron-containing layer and the thermal expansion coefficient of the ceramic layer forming the microcracks is 1: 2 or less. A material composed of a Si-SiC-based composite material and a plurality of oxidation-resistant protective layers formed on the carbonaceous material, and at least one of the plurality of oxidation-resistant protective layers is mainly composed of boron carbide. Including a boron-containing layer having a thickness of 10 μm to 500 μm , and on the boron-containing layer, a layer made of a ceramic selected from a Pyrex (registered trademark) glass layer or alumina, or an alumina / zirconia mixture , An oxidation-resistant protective layer having a thickness of 10 μm to 500 μm, and by forming this oxidation-resistant protective layer, when the carbonaceous material is kept in the atmosphere at least at 800 ° C. for 24 hours, the increase or decrease in weight is 0.5% or less A method for producing a carbonaceous material,
A boron-containing layer containing boron carbide as a main component as the oxidation-resistant protective layer on the surface of the carbonaceous material, and a Pyrex (registered trademark) glass layer or alumina or an alumina / zirconia mixture on the boron-containing layer. A method for producing the carbonaceous material, wherein the ceramic layer is formed by thermal spraying.   The carbonaceous material according to claim 7, wherein after the boron-containing layer is formed by thermal spraying, microcracks are formed in the layer by spraying a ceramic selected from alumina or an alumina / zirconia mixture. Production method.

Images