Cordierite sintered body and method for producing same

Abstract

The present invention pertains to a cordierite sintered body which contains all elements belonging to an element group M1 comprising calcium, magnesium, aluminum, and silicon, and in which, in terms of oxides, the contained amount of the calcium is 0.06-3.40 mass%, the contained amount of the magnesium is 12.9 mass% or more, the contained amount of an element M2 which is a metal element other than the elements belonging to the element group M1 is 1.5 mass% or less, the degree of porosity is 3.0 vol% or less, the 4-point flexural strength is 170 MPa or more, and the Weibull modulus is 9.5 or more.

Description

Cordierite sintered body and method for producing the same

[0001] The present invention relates to a cordierite sintered body and a method for producing the same.

[0002] Conventionally, a sintered body containing cordierite (a cordierite-based sintered body) has been used as a member exposed to plasma (Patent Document 1).

[0003] Japanese Patent Application Publication No. 9-295863

[0004] The inventors have found that conventional cordierite sintered bodies sometimes have insufficient plasma resistance. Furthermore, depending on the application, the cordierite sintered body may be required to have excellent thermal shock resistance.

[0005] The present invention has been made in view of the above points, and an object of the present invention is to provide a cordierite sintered body having excellent plasma resistance and thermal shock resistance, and a method for producing the same.

[0006] As a result of extensive research, the present inventors have found that the above object can be achieved by employing the following configuration, and have completed the present invention.

[0007] That is, the present invention provides the following [1] to

[11] . [1] A cordierite-based sintered body containing all elements belonging to an element group M1 consisting of calcium, magnesium, aluminum, and silicon, wherein the calcium content is 0.06% by mass or more and 3.40% by mass or less, calculated as oxide, the magnesium content is 12.9% by mass or more, calculated as oxide, and the content of element M2, a metal element other than an element belonging to the element group M1, is 1.5% by mass or less, calculated as oxide, the porosity is 3.0% by volume or less, the four-point bending strength is 170 MPa or more, and the Weibull coefficient is 9.5 or more. [2] The cordierite-based sintered body according to [1] above, wherein the calcium content is 0.09% by mass or more and 1.80% by mass or less, calculated as oxide. [3] The cordierite-based sintered body according to [1] or [2] above, wherein the aluminum content is 39.0% by mass or less, calculated as oxide. [4] The cordierite-based sintered body according to any one of [1] to [3] above, wherein the titanium content is 0.5 mass% or less, calculated as oxide. [5] The cordierite-based sintered body according to any one of [1] to [4] above, wherein the total content of iron, nickel, chromium, and manganese is 0.6 mass% or less, calculated as oxide. [6] The cordierite-based sintered body according to any one of [1] to [5] above, wherein the alkali metal content is 0.30 mass% or less, calculated as oxide. [7] The cordierite-based sintered body according to any one of [1] to [6] above, wherein the thermal conductivity is 4.0 W / (m K) or more. [8] The number of foreign particles containing the element M2, having an equivalent circle diameter of 5 μm or more, is 150 particles / cm. ２The cordierite-based sintered body according to any one of [1] to [7] above, which is the following: [9] A method for producing the cordierite-based sintered body according to any one of [1] to [8] above, comprising: preparing a compact using a raw material powder; heating the compact; and using, as the raw material powder, a mixed powder containing cordierite powder produced by an electric melting method, mullite powder, and magnesia powder.

[10] A method for producing the cordierite-based sintered body according to [9] above, wherein the mixed powder further contains calcium oxide powder.

[11] A method for producing the cordierite-based sintered body according to [9] or

[10] above, wherein the cordierite powder is used after magnetic separation.

[0008] According to the present invention, it is possible to provide a cordierite sintered body having excellent plasma resistance and thermal shock resistance, and a method for producing the same.

[0009] The meanings of terms used in the present invention are as follows: A numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0010] [Sintered body] The cordierite sintered body of the present invention contains all elements belonging to an element group M1 consisting of calcium, magnesium, aluminum, and silicon, and has a calcium content of 0.06 mass % or more and 3.40 mass % or less, calculated as oxide, of calcium, and a magnesium content of 12.9 mass % or more, calculated as oxide, of magnesium, a content of element M2 which is a metal element other than the elements belonging to the element group M1, calculated as oxide, of 1.5 mass % or less, a porosity of 3.0 vol % or less, a four-point bending strength of 170 MPa or more, and a Weibull coefficient of 9.5 or more.

[0011] Hereinafter, the cordierite sintered body will be referred to simply as "sintered body", and the cordierite sintered body of the present invention will also be referred to as "the present sintered body".

[0012] The present sintered body is a sintered body of a metal oxide containing cordierite. Cordierite is represented by the chemical formula, for example, 2MgO.2Al ２ O ３ 5SiO ２The present sintered body can be generally made of cordierite (2MgO.2Al ２ O ３ 5SiO ２ ), it further contains a specific amount of calcium (Ca). The present sintered body also contains a higher magnesium (Mg) content than ordinary cordierite. The present sintered body exhibits specific values ​​for porosity, four-point bending strength, and Weibull coefficient. Such a present sintered body has excellent plasma resistance and thermal shock resistance. The present sintered body will be described in more detail below.

[0013] <Element Group M1> As described above, the present sintered body is made of cordierite (2MgO.2Al ２ O ３ 5SiO ２ ), further contains calcium (Ca). Therefore, the present sintered body contains all elements belonging to element group M1, which is a metal element group consisting of calcium (Ca), magnesium (Mg), aluminum (Al), and silicon (Si).

[0014] <<Ca>> Because the plasma resistance of the present sintered body is excellent, the Ca content, calculated as oxide, is 0.06% by mass or more, preferably 0.09% by mass or more, more preferably 0.12% by mass or more, even more preferably 0.18% by mass or more, particularly preferably 0.24% by mass or more, and most preferably 0.40% by mass or more. For the same reasons and for improving the four-point bending strength and Weibull coefficient values, the Ca content is 3.40% by mass or less, preferably 2.50% by mass or less, more preferably 1.80% by mass or less, even more preferably 1.20% by mass or less, and particularly preferably 0.80% by mass or less. The Ca content calculated as oxide specifically refers to the CaO content. It is believed that an appropriate amount of Ca bonds the grains constituting the sintered body together or dissolves in the grains to strengthen the grains themselves, thereby reducing the rate of deterioration due to plasma and improving plasma resistance.

[0015] <<Mg>> Because the plasma resistance of the present sintered body is excellent, the Mg content, calculated as oxide, is 12.9 mass% or more, preferably 13.2 mass% or more, more preferably 13.5 mass% or more, even more preferably 14.0 mass% or more, even more preferably 14.5 mass% or more, particularly preferably 15.0 mass% or more, and most preferably 15.5 mass% or more. For the same reason, the Mg content, calculated as oxide, is preferably 17.5 mass% or less, more preferably 17.0 mass% or less, even more preferably 16.5 mass% or less, and particularly preferably 16.0 mass% or less. The Mg content calculated as oxide specifically means the content of MgO.

[0016] <<Al>> In the present sintered body, if the Al content is too high, the Mg content will be relatively low. Therefore, from the viewpoint of ensuring the desired Mg content, the Al content, in terms of oxide, is preferably 40.0 mass% or less, more preferably 39.0 mass% or less, even more preferably 38.0 mass% or less, particularly preferably 37.5 mass% or less, and most preferably 37.0 mass% or less. Note that if the Al content is too high, the Weibull coefficient value tends to be small. From this viewpoint, the Al content is preferably within the above range. On the other hand, there is no particular lower limit, and the Al content, in terms of oxide, is, for example, 30.0 mass% or more, preferably 33.0 mass% or more, more preferably 34.0 mass% or more, even more preferably 34.5 mass% or more, even more preferably 35.0 mass% or more, particularly preferably 35.5 mass% or more, and most preferably 36.0 mass% or more. Specifically, the Al content in terms of oxide is Al ２ O ３ means the content of

[0017] The content of metal elements (elements belonging to element group M1 and element M2, excluding Si) in the sintered body is measured by inductively coupled plasma mass spectrometry (ICP-MS). ３ The sample is immersed in an extractant with a mass ratio of 4:1 for 2 days, and then heated at 80°C for 1 hour. The sample is then removed using tweezers to obtain an extractant containing the metal elements extracted from the sample. The extractant is then dried and solidified, followed by immersion in HNO ３The solution is adjusted to a volume of 10 mL and analyzed using an apparatus manufactured by Agilent Technologies (Agilent 8800).

[0018] <<Si>> The Si content, calculated as oxide, is preferably 43.0 mass% or more, more preferably 44.0 mass% or more, even more preferably 45.0 mass% or more, even more preferably 46.0 mass% or more, particularly preferably 46.5 mass% or more, and most preferably 47.0 mass% or more. On the other hand, the Si content, calculated as oxide, is preferably 55.0 mass% or less, more preferably 51.0 mass% or less, even more preferably 50.0 mass% or less, particularly preferably 49.0 mass% or less, and most preferably 48.0 mass% or less. The Si content calculated as oxide specifically refers to SiO ２ means the content of

[0019] The Si content in a sintered body is determined as follows. First, a powder sample is taken from the center of the sintered body by polishing, and the total oxygen content Z1 in the sintered body is determined by infrared absorption using an oxygen / hydrogen analyzer (ROH-600 manufactured by LECO Corporation). The oxygen content Z3 is calculated by subtracting the oxygen content Z2 that is stoichiometrically bonded to elements contained in the sintered body (excluding silicon atoms) from the total oxygen content Z1 in the sintered body. In other words, oxygen content Z3 = total oxygen content Z1 - oxygen content Z2. Assuming that the entire amount of oxygen Z3 is used to bond with silicon atoms, oxygen content Z3 is calculated by subtracting the oxygen content Z2 from the total oxygen content Z1 in the sintered body. ２ The SiO thus obtained is converted into an amount. ２ The converted amount is the oxide-converted Si content (SiO ２ (content of

[0020] <Element M2> In the present sintered body, the content of metal elements other than the elements belonging to the above-mentioned element group M1 (i.e., impurities) is low. As a result, the present sintered body has excellent plasma resistance and thermal shock resistance. Specifically, the content of element M2, which is a metal element other than the elements belonging to the element group M1, is 1.5 mass% or less, preferably 1.1 mass% or less, more preferably 0.7 mass% or less, even more preferably 0.5 mass% or less, even more preferably 0.3 mass% or less, particularly preferably 0.2 mass% or less, and most preferably 0.1 mass% or less, in terms of oxide. The lower limit is preferably zero (0 mass%).

[0021] Examples of the element M2 include at least one element selected from the group consisting of titanium (Ti), iron (Fe), nickel (Ni), chromium (Cr), manganese (Mn), and alkali metals.

[0022] <<Ti>> Because the plasma resistance of the present sintered body is superior, the content of Ti, calculated as oxide, is preferably 0.5 mass% or less, more preferably 0.3 mass% or less, even more preferably 0.2 mass% or less, even more preferably 0.1 mass% or less, particularly preferably 0.05 mass% or less, and most preferably 0.03 mass% or less. Specifically, the content of Ti calculated as oxide is TiO ２ means the content of

[0023] <Fe, Ni, Cr, and Mn> The total content of Fe, Ni, Cr, and Mn, calculated as oxides, is preferably 0.6% by mass or less, more preferably 0.4% by mass or less, even more preferably 0.3% by mass or less, even more preferably 0.2% by mass or less, particularly preferably 0.1% by mass or less, and most preferably 0.05% by mass or less. In this case, the generation of foreign particles, which will be described later, is suppressed, the four-point bending strength and Weibull modulus are improved, and the thermal shock resistance of the sintered body is more excellent.

[0024] The content of Fe converted into oxide is specifically Fe ２ O ３ The Ni content calculated as an oxide specifically means the NiO content. The Cr content calculated as an oxide specifically means the Cr content.２ O ３ The content of Mn calculated as an oxide specifically means the content of MnO.

[0025] <<Alkali Metal>> Because the porosity of the present sintered body is lower and the plasma resistance and thermal shock resistance of the present sintered body are better, the content of the alkali metal, calculated as oxide, is preferably 0.30% by mass or less, more preferably 0.20% by mass or less, even more preferably 0.15% by mass or less, particularly preferably 0.12% by mass or less, and most preferably 0.09% by mass or less. However, for the same reason, it is preferable that a certain amount of alkali metal is contained. Specifically, the content of the alkali metal, calculated as oxide, is preferably 0.01% by mass or more, more preferably 0.03% by mass or more.

[0026] Examples of alkali metals include lithium (Li), sodium (Na), and potassium (K). The content of Li in terms of oxide is specifically Li ２ The oxide-equivalent Na content means the content of Na. ２ The content of K in terms of oxide specifically means the content of K. ２ It means the O content.

[0027] Other Elements Other examples of element M2 include copper (Cu), zinc (Zn), zirconium (Zr), gallium (Ga), phosphorus (P), and sulfur (S). Although P and S are not metal elements, they are considered to be metal elements when treated as element M2. The total content of other elements, calculated as oxides, is preferably 0.04 mass% or less, more preferably 0.04 mass% or less, and even more preferably 0.03 mass% or less. The Cu content calculated as oxides specifically refers to the CuO content. The Zn content calculated as oxides specifically refers to the ZnO content. The Zr content calculated as oxides specifically refers to ZrO. ２ The Ga content calculated as an oxide specifically means the Ga content. ２ O ３The oxide-equivalent P content specifically means P ２ O ５ The content of S converted into oxide specifically means the content of SO ３ means the content of

[0028] <Porosity> Because the present sintered body has excellent plasma resistance and thermal shock resistance, the porosity of the present sintered body is 3.0 vol% or less, preferably 1.5 vol% or less, more preferably 0.5 vol% or less, even more preferably 0.3 vol% or less, particularly preferably 0.1 vol% or less, and most preferably 0.05 vol% or less. The lower limit is preferably zero (0 vol%).

[0029] In order to achieve the porosity within the above range, it is preferable to adjust the contents of each component to the above-described ranges and to produce a sintered body by the method (the present production method) described below. In particular, it is preferable to use cordierite powder produced by an electric melting method as the raw material powder.

[0030] The porosity is determined in accordance with the calculation method for open porosity described in JIS R 1634:1998 "Method for measuring density and open porosity of sintered fine ceramics."

[0031] <Four-point bending strength> Because the present sintered body has excellent thermal shock resistance, the four-point bending strength of the present sintered body is 170 MPa or more, preferably 180 MPa or more, more preferably 190 MPa or more, even more preferably 200 MPa or more, even more preferably 210 MPa or more, particularly preferably 220 MPa or more, and most preferably 230 MPa or more. The upper limit is not particularly limited, and the four-point bending strength of the present sintered body is, for example, 300 MPa or less, preferably 250 MPa or less.

[0032] The four-point bending strength is measured in accordance with JIS R 1601 (2008) on a test piece of the sintered body (flat plate, length 50 mm, width 4 mm, thickness 3 mm) at 25°C.

[0033] In order to achieve the four-point bending strength within the above range, it is preferable to set the contents of each component as described above and to produce the sintered body by the method (the present production method) described below. In particular, when the contents of Fe, Ni, Cr, and Mn are high, it is difficult to achieve such a four-point bending strength.

[0034] <Weibull Coefficient> Because the present sintered body has excellent thermal shock resistance, the Weibull coefficient of the present sintered body is 9.5 or more, preferably 10.0 or more, more preferably 10.5 or more, even more preferably 11 or more, even more preferably 11.5 or more, particularly preferably 12 or more, and most preferably 12.5 or more. There is no particular upper limit, and the Weibull coefficient of the present sintered body is, for example, 14 or less, preferably 13 or less.

[0035] The Weibull coefficient (Weibull coefficient of four-point bending strength) is an index showing the degree of variation in four-point bending strength, and a larger value means a smaller variation in four-point bending strength. The Weibull coefficient is determined as follows: First, the four-point bending strength of 30 test pieces is measured using the method described above. Next, the Weibull coefficient is calculated in accordance with JIS R 1625 (2010) using the bending strength data of the 30 measured pieces.

[0036] In order to achieve the Weibull coefficient in the above range, it is preferable to set the contents of each component to the above range and to produce the sintered body by the method (the present production method) described below. In particular, when the contents of Fe, Ni, Cr, and Mn are high, it is difficult to obtain such a Weibull coefficient.

[0037] <Thermal Conductivity> Because the thermal shock resistance of the present sintered body is superior, the thermal conductivity of the present sintered body is preferably 4.0 W / (m K) or more, more preferably 4.2 W / (m K) or more, even more preferably 4.4 W / (m K) or more, even more preferably 4.6 W / (m K) or more, particularly preferably 4.8 W / (m K) or more, and most preferably 5.0 W / (m K) or more. There is no particular upper limit, and the thermal conductivity of the present sintered body is, for example, 6.0 W / (m K) or less, preferably 5.5 W / (m K) or less.

[0038] The thermal conductivity is measured for a test piece of the sintered body (12 mm x 12 mm plate, 6.0 mm thick) using a laser flash method thermal property measuring device "Xenon Flash Analyzer LFA 467 HyperFlash" manufactured by NETZSCH under the condition of 21°C.

[0039] In order to achieve the thermal conductivity within the above range, it is preferable to adjust the content of each component to the above range and to produce a sintered body by the method (this production method) described below. In this way, it is preferable to obtain a dense sintered body with reduced impurities.

[0040] <Amount of Heterogeneous Phases (Number of Foreign Particles)> Using a scanning electron microscope (SEM), the sintered body is observed at a magnification of 1,000 times, and SEM images of 50 random fields of view are obtained. From the obtained SEM images, foreign particles containing element M2 (particles composed of element M2) are identified using an EDX (energy dispersive X-ray spectroscopy) device attached to the SEM. Of the identified foreign particles, the number of foreign particles having a circle equivalent diameter of 5 μm or more (unit: particles / cm ２ ) is measured and the average value of 50 fields of view is calculated. The calculated average value is the number of foreign particles in the sintered body. In this specification, the number of foreign particles may be referred to as the "amount of foreign phase" for convenience.

[0041] The amount of heterogeneous phase, i.e., the number of foreign particles containing element M2 having an equivalent circle diameter of 5 μm or more, is set to 150 particles / cm because the four-point bending strength and Weibull coefficient of this sintered body are good and the thermal shock resistance is superior. ２ Preferably, 100 or less per cm ２ More preferably, 50 or less particles / cm ２ More preferably, 30 or less per cm ２ More preferably, 10 or less particles / cm ２ Particularly preferred is 5 or less per cm ２ The lower limit is most preferably zero (0 particles / cm ２ ) is preferred.

[0042] In order to set the amount of different phases within the above range, it is preferable to set the contents of each component as described above and to produce the sintered body by the method (the present production method) described below.

[0043] <Shape and Use> The shape of the present sintered body can be selected appropriately depending on the use, such as a plate (for example, a disk or a flat plate), a sphere, or an oblong spheroid. The present sintered body is preferably used as a susceptor material for supporting a wafer in a semiconductor manufacturing device, but the use of the present sintered body is not limited to this.

[0044] [Method for manufacturing sintered body] Next, a method for manufacturing the present sintered body (hereinafter also referred to as "the present manufacturing method") will be described. In summary, the present manufacturing method is a method for producing a compact using raw material powder and heating this compact. The present manufacturing method will be described in detail below.

[0045] <Raw Material Powder> As the raw material powder, a mixed powder containing cordierite powder produced by an electric melting method, mullite powder, and magnesia powder is used.

[0046] <Cordierite powder> Cordierite (2MgO 2Al ２ O ３ 5SiO ２ The cordierite powder is a raw material for Mg, Al, and Si that constitute the present sintered body. Furthermore, the cordierite powder may contain Ca as an impurity, and in this case, the cordierite powder supplies the Ca that constitutes the present sintered body.

[0047] (Fused Cordierite Powder) In the present manufacturing method, cordierite powder manufactured by an electric melting method (for convenience, also referred to as "fused cordierite powder") is used. The method for obtaining the fused cordierite powder is roughly as follows, for example. First, raw materials for the fused cordierite powder are placed in a crucible. Examples of raw materials for the fused cordierite powder include magnesia (MgO), alumina (Al ２ O ３ ), silica (SiO ２) and the like. These raw materials may contain impurities such as Ca. Next, for example, plasma is generated using carbon electrodes to melt the raw materials in the crucible. The molten raw materials are then air-shattered and rapidly cooled. This results in electrofused cordierite powder. Electrofused cordierite powder is a primarily amorphous substance (powder) containing some crystals. The particles constituting electrofused cordierite powder are spherical and have a uniform particle size. In other words, it is homogeneous. For this reason, electrofused cordierite powder is easily sintered in the presence of mullite powder, a sintering aid described below. In other words, it has good sinterability. As a result, a dense sintered body can be obtained, and porosity can be reduced. Furthermore, impurities such as Ti can be reduced by manufacturing it using an electric melting method. Commercially available electrofused cordierite powder can be used, and a specific example of such a powder is ELP-150FINE (manufactured by AGC Ceramics Co., Ltd.).

[0048] Mullite powder: Mullite is, for example, 3Al ２ O ３ 2SiO ２ , 2Al ２ O ３ SiO ２ Mullite powder is used as a sintering aid. By using mullite powder as a sintering aid, a dense sintered body can be obtained. Mullite powder is the raw material for Al and Si that make up this sintered body.

[0049] <<Magnesia Powder>> Magnesia (MgO) powder is a raw material for Mg that constitutes the present sintered body. As described above, the present sintered body has a higher Mg content than ordinary cordierite, and therefore magnesia powder is further used as a raw material powder.

[0050] <<Calcium Oxide Powder>> The raw material powder can further contain calcium oxide (CaO) powder. As described above, the present sintered body further contains Ca in addition to cordierite. Therefore, if the Ca contained as an impurity in the cordierite powder is insufficient, calcium oxide powder is further used as the raw material powder.

[0051] <<Magnetic Separation>> Each powder used as a raw material powder, particularly an electrofused cordierite powder, is preferably magnetically separated before use. This allows the content of element M2 (Ti, Fe, etc.), which is a metal element other than elements belonging to element group M1 (Ca, Mg, Al, and Si), in the finally obtained present sintered body to be reduced. A suitable example of a magnetic separation method is a method using a wet magnetic filter. The magnetic separation conditions are not particularly limited, and may be appropriately adjusted, for example, so that the desired content of element M2 is achieved in the obtained present sintered body.

[0052] <<Preparation of Raw Powder>> The above-mentioned powders are mixed after magnetic separation if necessary. This gives a raw powder which is a mixed powder of the powders. The mixing method is not particularly limited, and a conventionally known method can be used. The content of each powder in the raw powder (mixed powder) is adjusted appropriately so that the content of each component in the final sintered body is the desired amount. The mixed powder is preferably pulverized to reduce the particle size in order to improve the sinterability during heating, which will be described later. Specifically, the average particle size of the mixed powder after pulverization is preferably 10 μm or less, more preferably 2 μm or less. The average particle size is determined by the particle size at 50% of the integrated value in the particle size distribution (D ５０ The pulverization method is not particularly limited, and pulverization can be performed using a ball mill, an attritor, a bead mill, a jet mill, or the like. When wet pulverization is performed, the mixed powder after pulverization is dried.

[0053] <Preparation of Molded Body> Next, a molded body is prepared using the raw material powder (mixed powder). That is, it is molded. The molding method is not particularly limited, and a general molding method can be used. For example, molding is performed using an isostatic press at a pressure of 100 MPa or more and 200 MPa or less. As an alternative method, a mixture of the mixed powder and an organic binder may be molded into a predetermined shape by press molding, extrusion molding, sheet molding, or the like. The shape obtained by molding is appropriately selected depending on the application of the sintered body to be obtained, etc.

[0054] <Heating> Next, the obtained molded body is heated. This results in a sintered body. From the viewpoint of improving sinterability, the heating temperature (maximum temperature during heating) is preferably 1400°C or higher, more preferably 1410°C or higher, and even more preferably 1430°C or higher. On the other hand, if the heating temperature is too high, a portion of the obtained sintered body may melt and be damaged, or a sintered body of the desired dimensions may not be obtained. Therefore, the heating temperature is preferably 1450°C or lower, more preferably 1440°C or lower. The heating time (holding time at the maximum temperature) is preferably 1 hour or longer, more preferably 2 hours or longer, and even more preferably 5 hours or longer. On the other hand, the heating time is preferably 48 hours or shorter, more preferably 12 hours or shorter, and even more preferably 8 hours or shorter. The atmosphere during heating (heating atmosphere) is not particularly limited, and examples thereof include air atmosphere; inert atmospheres such as nitrogen and argon atmospheres; and reducing atmospheres such as hydrogen atmospheres and mixed atmospheres of hydrogen and nitrogen.

[0055] The obtained sintered body is preferably densified. Densification is performed, for example, using a hot isostatic press. Specifically, for example, the sintered body is heated at a temperature of 1000°C to 1350°C while applying a pressure of 100 MPa to 200 MPa using a hot isostatic press.

[0056] The present invention will be specifically described below using examples. However, the present invention is not limited to the examples described below. Examples 1 to 2, 5 to 9, 11 to 12, 14 to 17, 19 to 21, and 23 to 25 are examples, and Examples 3 to 4, 10, 13, 18, and 22 are comparative examples.

[0057] Examples 1 to 25 The sintered bodies of the respective examples were obtained as follows.

[0058] Raw material powder: Electrofused cordierite (2MgO 2Al ２ O ３ 5SiO ２ ) powder and mullite (3Al) as a sintering aid. ２ O ３ 2SiO ２) powder, magnesia (MgO) powder, and calcium oxide (CaO) powder were mixed. As the electrofused cordierite powder, "ELP-150FINE" (average particle size: 14.1 μm) manufactured by AGC Ceramics Co., Ltd. was used. As the mullite powder, "KM101" (average particle size: 0.8 μm) manufactured by Kyoritsu Material Co., Ltd. was used. Specifically, the powders were mixed so that the contents of elements belonging to element group M1 and element M2 in the resulting sintered body would be the values ​​shown in Tables 1 to 3 below, thereby obtaining a raw material powder that was a mixed powder. At this time, titanium oxide (TiO ２ Powders of other metal oxides, such as SiO 2 , SiO 3 , SiO 4 , ...

[0059] Each powder was subjected to magnetic separation before mixing. Specifically, a wet magnetic filter ("Wet High Magnetic Flux Tester FG Type" manufactured by Nippon Magnetic Separation Co., Ltd.) was used to disperse each powder in water to prepare a slurry (concentration: 15% by volume), which was then subjected to magnetic separation three times under conditions of 2.8 Tesla. However, in Examples 16 to 18, magnetic separation was not performed on each powder.

[0060] The raw material powder (mixed powder) was wet mixed and pulverized using a ball mill with high-purity alumina balls and ethanol as a dispersion medium. The average particle size (D ５０ ) was 2.0 μm.

[0061] <<Preparation and Heating of Compacted Body>> The obtained raw material powder (mixed powder) was pressed at room temperature using an isostatic press at a pressure of 180 MPa to produce a compact. The produced compact was then heated in the atmosphere to obtain a sintered body. The heating temperature was 1430°C and the heating time was 5 hours. The obtained sintered body was then densified. Specifically, it was heated at 1300°C while applying a pressure of 145 MPa using a hot isostatic press. However, in Examples 24 and 25, densification was not performed.

[0062] <Contents of Elements Belonging to Element Group M1 and Element M2> For each sintered body, the contents of the elements belonging to element group M1 and element M2, calculated as oxides, were determined by the method described above. The results are shown in Tables 1 to 3 below.

[0063] <Porosity, etc.> For each sintered body, the porosity, amount of heterogeneous phases, four-point bending strength, Weibull coefficient, and thermal conductivity were determined by the methods described above. The results are shown in Tables 1 to 3 below.

[0064] <Thermal Shock Resistance Test> Test pieces measuring 15 mm x 5 mm x 100 mm were cut from the sintered body. The test pieces were heated at 350°C for 60 minutes and then dropped into water at room temperature. Next, the test pieces were removed from the water, and cracks in the test pieces were stained using a dye penetrant (Taseto Co., Ltd., penetrant FP-S and developer FD-S) and visually inspected. Tables 1 to 3 below show the following: "○" if no cracks of 3 mm or more were observed; "△" if one to two cracks of 3 mm or more were observed; and "×" if three or more cracks of 3 mm or more were observed. A rating of "○" or "△" indicated excellent thermal shock resistance.

[0065] <Etching Amount> For each sintered body, the etching amount was determined to evaluate plasma resistance. Specifically, a test piece measuring 10 mm x 5 mm x 4 mm was cut out from the sintered body, and the 10 mm x 5 mm surface was mirror-finished. A portion of the mirror-finished surface was masked with Kapton (registered trademark) tape and etched with plasma gas. Thereafter, the etching amount was determined by measuring the step between the etched and non-etched portions using a stylus surface profiler (ULVAC, Dectak150). The plasma etching apparatus used was EXAM (manufactured by Shinko Seiki Co., Ltd., model: POEM type). In RIE mode (reactive ion etching mode), CF ４ The etching was performed for 390 minutes with gas. The smaller the etching amount (unit: nm), the better the plasma resistance can be evaluated. Specifically, an etching amount of 420 nm or less was evaluated as having excellent plasma resistance.

[0066]

[0067]

[0068]

[0069] <Summary of Evaluation Results> As shown in Tables 1 to 3 above, the sintered bodies of Examples 1 to 2, 5 to 9, 11 to 12, 14 to 17, 19 to 21 and 23 to 25 were found to be excellent in plasma resistance and thermal shock resistance.

[0070] In contrast, the sintered bodies of Examples 3 to 4, 10, 13, 18, and 22 were insufficient in at least one of plasma resistance and thermal shock resistance. Specifically, the results were as follows: In Example 3, the MgO content was less than 12.9% by mass, the etching amount was large, and the plasma resistance was insufficient. In Example 4, the CaO content was less than 0.06% by mass, the etching amount was large, and the plasma resistance was insufficient. In Example 10, the MgO content was less than 12.9% by mass, the etching amount was large, and the plasma resistance was insufficient. Furthermore, in Example 10, the CaO content was more than 3.40% by mass, the four-point bending strength was less than 170 MPa, and the Weibull coefficient was less than 9.5, and the thermal shock resistance was insufficient. In Example 13, the CaO content was less than 0.06% by mass, the etching amount was large, and the plasma resistance was insufficient. In Example 18, the CaO content was less than 0.06% by mass, the etching amount was large, and the plasma resistance was insufficient. Furthermore, Example 18 had a Weibull modulus of less than 9.5, and thus had insufficient thermal shock resistance. Example 22 had a Weibull modulus of less than 9.5, and thus had insufficient thermal shock resistance.

[0071] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2021-035458) filed on March 5, 2021, the contents of which are incorporated herein by reference.

Claims

1. Contains all elements belonging to an element group M1 consisting of calcium, magnesium, aluminum and silicon, The calcium content is 0.06% by mass or more and 3.40% by mass or less in terms of oxide, The magnesium content is 12.9% by mass or more in terms of oxide, The content of element M2, which is a metal element other than the elements belonging to the element group M1, is 1.5 mass% or less in terms of oxide, The total content of iron, nickel, chromium and manganese is 0.1 mass% or less in terms of oxides, The porosity is 3.0 vol% or less, The four-point bending strength is 170 MPa or more, A cordierite sintered body having a Weibull coefficient of 9.5 or more.

2. 2. The cordierite sintered body according to claim 1, wherein the calcium content is 0.09 mass % or more and 1.80 mass % or less in terms of oxide.

3. A cordierite sintered body as described in claim 1 or 2, wherein the calcium content, calculated as oxide, is 0.247 mass% or less.

4. The cordierite sintered body according to any one of claims 1 to 3, wherein the aluminum content is 39.0 mass% or less in terms of oxide.

5. A cordierite sintered body according to any one of claims 1 to 4, wherein the aluminum content, calculated as oxide, is 35.5 mass% or more.

6. A cordierite sintered body according to any one of claims 1 to 5, wherein the magnesium content, calculated as oxide, is 13.5 mass% or more.

7. The cordierite sintered body according to any one of claims 1 to 6, wherein the titanium content is 0.5 mass% or less in terms of oxide.

8. The cordierite sintered body according to any one of claims 1 to 7, wherein the content of the alkali metal is 0.30 mass% or less in terms of oxide.

9. The cordierite sintered body according to any one of claims 1 to 8, having a thermal conductivity of 4.0 W / (m·K) or more.

10. The number of foreign particles containing the element M2 having a circle equivalent diameter of 5 μm or more is 150 particles / cm ２ The cordierite sintered body according to any one of claims 1 to 9, wherein:

11. A method for producing the cordierite sintered body according to any one of claims 1 to 10, comprising the steps of: A compact is produced using the raw material powder, Heating the molded body, A method for producing a cordierite sintered body, comprising using a mixed powder containing cordierite powder produced by an electric melting method, mullite powder, and magnesia powder as the raw material powder.

12. The method for producing a cordierite sintered body according to claim 11, wherein the mixed powder further contains calcium oxide powder.

13. The method for producing a cordierite sintered body according to claim 11 or 12, wherein the cordierite powder is magnetically separated before use.