JP5094214B2 - Method for producing alumina sintered body - Google Patents

Description

The present invention relates to the orientation of the alumina crystal particles in the alumina sintered body, to reduce the orientation of the alumina crystal particles relates to the production how uniformly possible to shrink an alumina sintered body by firing Is.

  Conventionally, ceramics are used in many fields. Among the ceramics, alumina-based sintered bodies are used in various industrial fields because they are obtained at a lower cost than other ceramics and have excellent mechanical, thermal, and electrical properties and high corrosion resistance. This is the current situation.

  This alumina sintered body can be used for various applications ranging from small semiconductor parts to large refractories and semiconductor / liquid crystal manufacturing equipment parts. Alumina sintered body is manufactured as a product.

  However, since the primary raw material particles of the alumina sintered body are generally flat particles having a high aspect ratio, the primary raw material particles are likely to be partially oriented depending on the production method. When partial orientation occurs in the next raw material particles, a difference occurs in the shrinkage direction and shrinkage rate in the firing step within the same sintered body. If there is a difference between the shrinkage direction and shrinkage rate, internal stresses are generated in the sintered body, regardless of the size of the product, and this internal stress exceeds the strength of the sintered body or is structurally weak. There is a problem that the sintered body is cracked or broken. Furthermore, the orientation of the alumina crystal particles often occurs with a variation in the directionality of each part of the product, and between the part with orientation and the part with no orientation or the part with another orientation. Due to the difference in shrinkage direction and shrinkage rate, internal stress was generated, which caused a problem that the sintered body was cracked or broken. In particular, for products manufactured using the casting method, alumina primary materials, a binder, a dispersant, and a solvent are mixed to form a slurry, and this slurry is poured into a mold, so that alumina crystals are produced along the slurry flow. The particles are likely to be oriented, which causes the generation of stress inside the sintered body. As a result, there is a problem in that the sintered body is cracked or broken and the product cannot be manufactured.

  In response to this problem, each ceramic manufacturer uses a manufacturing method that does not cause the crystal grains to be oriented, and conversely, the crystal grains are oriented so that the direction of shrinkage is constant within the product. In order to prevent or control the generation of cracks, the alumina sintered body is prevented from being cracked or broken.

For example, Patent Document 1 discloses a molded body for a sintered ceramic body that contains an α-alumina raw material as a single element or as a component, and uses the peak intensity obtained by X-ray diffraction measurement of the surface of the molded body. Sintering in which α-alumina crystal orientation ratio calculated as ₁₀₄ / (I ₁₀₄ + I ₀₃₀ ) is 0.5 to 0.8, α-alumina particles are irregularly arranged, and a compact density is finally obtained. A molded body for a sintered ceramic body having a density of 40% or more with respect to the theoretical density of the body is disclosed. In the examples, β-alumina having an orientation ratio = I ₀₀₆ / I ₁₁₀ of 0.8 to 1.2 An example of a sintered body is disclosed. And according to this invention, since the particle orientation of α-alumina in the molded body is controlled to be within a predetermined range, even if this is fired, there is almost no influence of the firing process, and the firing after firing is not affected. It is disclosed that the effect of making it difficult to orient the particles is also obtained.
JP-A-9-255413

However, in the invention described in Patent Document 1, the orientation ratio (I ₀₀₆ / I ₁₁₀ ) determined from the peak intensity ratio between the (006) plane and the (110) plane on the X-ray diffraction chart of the β-alumina sintered body. ) Is as high as 0.8 to 1.2, and in the β-alumina sintered body, many alumina crystal grains are oriented to the (006) plane which is the c-axis. In such a β-alumina sintered body, as described above, there is a difference in the shrinkage rate between the shrinkage in the c-axis direction and the shrinkage in the direction perpendicular to the c-axis, and this becomes an internal stress in the sintered body. It acts on the part where stress concentration tends to occur structurally, and there is a high possibility that the sintered body will crack or break. Furthermore, the value of this orientation rate is merely a ratio of the alumina crystal particles oriented in the (006) plane and the (110) plane in terms of numerical values, and actually the orientation rate in each part of the sintered body. There is variation, which also generates stress, which can cause cracks and breakage.

The invention described in Patent Document 1 is applicable only to the production of a small β-alumina sintered body having a length of 140 mm and a thickness of about 2.4 mm. In the bonded body, the internal stress generated in each part of the sintered body due to the orientation of the alumina crystal particles is small, and the sintered body is less likely to cause cracks or breakage. Therefore, the orientation ratio (I ₀₀₆ / I ₁₁₀ ) determined from the peak intensity ratio between the (006) plane and the (110) plane on the X-ray diffraction chart of the β-alumina sintered body is as high as 0.8 to 1.2. Even if it is a value, it is considered that cracks and breakage are less likely to occur. However, if the orientation ratio range disclosed in Patent Document 1 is applied to an alumina sintered body having a length exceeding 1 m, the internal stress difference generated in each part due to the orientation of the alumina crystal particles is extremely large. A problem arises that the sintered body is cracked or broken.

  Further, as another method, a method of controlling the orientation of the alumina crystal particles by performing molding while applying a magnetic force is conceivable. However, with such a method, it is difficult to manufacture a complex and large-sized alumina product. There has been a demand for an alumina sintered body having no orientation that generates internal stress that causes cracks and breakage inside.

The present invention has been devised to solve the above problems, and is suitable for a semiconductor or liquid crystal manufacturing apparatus stage member which is a ceramic member whose size is being increased. method for producing a generator less alumina sintered body, and to provide a manufacturing method particularly using a casting molding method.

In the method for producing an alumina sintered body of the present invention, the peak intensity ratio I ₀₀₆ / I ₁₁₀ between the (006) plane and the (110) plane in the X-ray diffraction chart of the surface and the cross section of the central portion is in the range of 0.02 to 0.07. And a primary raw material particle of α-alumina having an average particle size of 0.5 to 2.0 μm and a particle shape ratio of 1.5 to 2.0, an emulsion binder, and a dispersant. Mixing with a solvent, α-alumina primary raw material particles have a particle volume fraction of 25 to 45% by volume , solidified or curable, and a slurry with a viscosity of 0.02 to 0.5 Pa · s. Pour into a liquid mold, heat the mold to 50 to 100 ° C., destroy the emulsion state of the binder to produce a solidified body, take out the solidified body from the mold and heat it. An α-alumina molded body obtained by evaporating and curing the solvent component After obtaining, it is characterized in firing the α- alumina formed body.

In addition, in the method for producing an alumina sintered body of the present invention, the peak intensity ratio I ₀₀₆ / I ₁₁₀ between the (006) plane and the (110) plane in the X-ray diffraction chart of the surface and cross section of the end is 0.02 to 0.5. Is a method for producing a long-sized alumina sintered body having a rod-like shape, a cylindrical shape, a plate-like shape, a column-like shape, etc., in which the average particle size is 0.5 to 2.0 μm and the particle size ratio is 1.5 to 2.0 Α-alumina primary raw material particles, a binder in an emulsion state, a dispersant, and a solvent are mixed so that the particle volume fraction of the α-alumina primary raw material particles is 25 to 45% by volume , and is solidified or curable. And the viscosity is 0.02 to 0.5
The slurry is Pa · s , and the slurry is poured into a non-liquid-absorbing mold, and the mold is 50 to 100 ° C.
To obtain an α-alumina molded body by destroying the emulsion state of the binder to produce a solidified body, removing the solidified body from the mold and heating to evaporate and cure the solvent component. Thereafter, the α-alumina shaped body is fired.

Furthermore, the method for producing an alumina sintered body of the present invention is based on the X-ray diffraction chart (006) of the center surface, the first cross section perpendicular to the surface, and the second cross section perpendicular to the surface and the first cross section. ) Plane and (110) plane peak intensity ratio I ₀₀₆ / I ₁₁₀ are both in the range of 0.02 to 0.07, and the average particle size is 0.5 to 2.0 μm. Α-alumina primary raw material particles having a particle size ratio of 1.5 to 2.0, an emulsion binder, a dispersant, and a solvent are mixed, and the particle volume fraction of the α-alumina primary raw material particles is 25 to 45 vol%. and then, in the solidifying or curing, viscosity and slurry 0.02~0.5Pa · s, the slurry is injected into the non-absorbent mold, heating the forming die to 50 to 100 ° C., the binder The emulsion state is broken to produce a solidified body, and the solidified form from the mold After obtaining the solvent component is evaporated cured α- alumina molded article by heating is taken out, and is characterized in firing the α- alumina formed body.

Further, the method for producing an alumina sintered body of the present invention is based on the X-ray diffraction chart of the end surface, the first cross section perpendicular to the surface, and the second cross section perpendicular to the surface and the first cross section (006). ) Plane and (110) plane peak intensity ratio I ₀₀₆ / I ₁₁₀ are all in the range of 0.02 to 0.5. A production method comprising mixing α-alumina primary raw material particles having an average particle size of 0.5 to 2.0 μm and a particle shape ratio of 1.5 to 2.0, an emulsion binder, a dispersant, and a solvent; The alumina primary raw material particle volume fraction is 25-45% by volume , solidified or curable, and the viscosity is 0.02-0.5 Pa · s , and the slurry is poured into a non-absorbing mold, The mold is heated to 50 to 100 ° C. to destroy the emulsion state of the binder and solidify. The solidified body is taken out from the mold and heated to evaporate and cure the solvent component to obtain an α-alumina molded body, and then the α-alumina molded body is fired. It is.

In the method for producing an alumina sintered body according to the present invention, in any one of the above structures, at least one of the inner surfaces of the mold has a width of 10 mm or more and a length of 1500 mm or more. It is a feature.

According to the method for producing an alumina sintered body of the present invention, α-alumina primary raw material particles having an average particle diameter of 0.5 to 2.0 μm and a particle shape ratio of 1.5 to 2.0, an emulsion binder, and a dispersant Mixing with a solvent, α-alumina primary raw material particles have a particle volume fraction of 25 to 45% by volume , solidified or curable, and a slurry with a viscosity of 0.02 to 0.5 Pa · s. It is poured into a liquid-absorbing mold, the mold is heated to 50 to 100 ° C., the binder emulsion state is broken to produce a solidified body, the solidified body is taken out from the mold and heated to remove the solvent component. After the α-alumina molded body is obtained by evaporating and curing, the space between the raw material particles in the slurry can be expanded to reduce the interaction such as van der Waals force between the particles. And when the slurry viscosity is lowered and the slurry is injected Shear stress acting on the slurry becomes possible to reduce. Thereby, when injecting the slurry, the orientation of particles generated along the flow direction of the slurry can be suppressed, and the difference in shrinkage rate can be suppressed in the firing process, so that the internal stress is the alumina sintered body. It is possible to effectively prevent the occurrence of cracks and breakage by concentrating on the portion where stress is easily concentrated inside. Moreover, this manufacturing method can make the alumina sintered body suppress the orientation of the alumina crystal particles.

  Further, according to the method for producing an alumina sintered body of the present invention, when at least one surface of the inner surface of the molding die into which the slurry is injected has a width of 10 mm or more and a length of 1500 mm or more, In this production method, it is possible to produce a large-sized alumina sintered body that cannot be formed into a product due to cracks or breakage in the sintered body after firing even though a molded body is obtained. .

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  Alumina sintered compacts can be obtained at a relatively low cost while having superior mechanical, thermal, and electrical properties and high corrosion resistance compared to other ceramics. And is used in various industrial fields. However, the α-alumina primary raw material particles used for the production of the alumina sintered body are flat with a high aspect ratio, and depending on the production method, the orientation of the α-alumina primary raw material particles may be In the firing process, a difference in shrinkage direction and shrinkage rate is generated, which may cause internal stress in the alumina sintered body, and may cause cracks or breakage in portions where stress is likely to concentrate. For example, in the case of a powder press molding method, even flat α-alumina primary raw material particles having a high aspect ratio are randomly filled in a mold and subjected to compression molding, so the orientation of the raw material particles is remarkable. However, although there are few cracks and breakages in the sintered body, it is difficult to obtain a large product having a length exceeding 1 m, which is currently required, by the powder press molding method. On the other hand, there is a cast molding method as a molding method capable of dealing with large products.

  However, the casting molding method using a non-liquid-absorbing mold among the casting molding methods is to solidify or harden by filling a non-liquid-absorbing mold with a solidifying or curable slurry and heating it. It is a molding method to obtain a ceramic molded body by drying, but when filling the slurry into this non-liquid-absorbing mold, there are various methods depending on the filling method and the slurry hits the inner wall of the mold immediately after filling. A smooth slurry flow occurs. At this time, the flat α-alumina primary raw material particles having a high aspect ratio are partially arranged in various directions along the flow of the various slurries. Then, with the α-alumina primary raw material particle array partially oriented in various directions as described above, the slurry is solidified or cured, dried to form a ceramic formed body, and further fired to obtain an alumina-based sintered body. When trying to obtain a bonded body, internal stresses with various orientations are generated inside the alumina sintered body, and this internal stress causes cracks and breaks in the weakly bonded parts of the alumina sintered body. Will occur.

  This tendency becomes more prominent as the size of the alumina sintered body is larger, and cracks and breakage are particularly likely to occur in a large alumina sintered body used for a semiconductor or a stage member for a liquid crystal manufacturing apparatus.

  Therefore, in the production of the α-alumina sintered body by the casting method, the arrangement of the α-alumina primary raw material particles in the slurry along the flow of the slurry is reduced as much as possible, and the sintered sintered crystal particles It is necessary to make the orientation of a certain range. Here, in order to confirm the orientation of the crystal grains of the α-alumina sintered body, the surface or cross section of the α-alumina sintered body is measured by X-ray diffraction, and each crystal plane of the X-ray diffraction chart is measured. From the peak intensity, it is possible to confirm in which direction the alumina crystal particles are oriented.

  This crystal plane is represented by the Miller index. This Miller index indicates which axis of the a-axis, b-axis, and c-axis intersects with three integers in parentheses such as (006). To a-axis, b-axis, and c-axis, and the intersecting axes are represented by positive integers (an integer of 1 or more). Therefore, (006) indicates that the crystal is oriented on the plane that intersects the c-axis, and (110) indicates that the crystal is oriented on the plane that intersects the a-axis and the b-axis. And (110) plane can be confirmed to confirm the orientation of crystal grains in the sintered body.

FIG. 1 is an X-ray diffraction chart showing an example of an X-ray diffraction measurement result of an α-alumina sintered body produced by the production method of the present invention. The vertical axis in FIG. 1 indicates the peak intensity, and the horizontal axis indicates the diffraction angle. In this chart, the (006) plane crystal peak exists between diffraction angles (2θ) = 41 ° to 42 °, and the (110) plane crystal peak exists between diffraction angles (2θ) = 37 ° to 38 °. Yes.

From the relationship between the (006) plane crystal peak intensity and the (110) plane crystal peak intensity of the X-ray diffraction chart shown in FIG. 1, the present inventors have determined the surface and cross section of the central portion of the α-alumina sintered body. In the X-ray diffraction, the peak intensity ratio I ₀₀₆ / I ₁₁₀ between the (006) plane and the (110) plane is in the range of 0.02 to 0.07, so that cracks and breakage occur in the alumina sintered body. It was found that the presence or absence of stress can be recognized indirectly and a good alumina sintered body can be obtained. In the case of a plate-like body, the central portion of the α-alumina sintered body refers to the vicinity of the position where the center line in the length direction and the center line in the width direction intersect.

When the value of the peak intensity ratio I ₀₀₆ / I ₁₁₀ of the surface and cross section of the central portion of the α-alumina sintered body is less than 0.02, the crystal particles in the α-alumina sintered body are other than the c-axis. In such a state, the α-alumina primary raw material particles are in a flat shape having a high aspect ratio, so that the particles are compared with the portion having an orientation. The contact area between them becomes small. When the contact area is reduced in this way, a constricted part called a neck is formed at the contact part between the particles, and a lot of heat energy is required for the development of this neck for sintering. Alternatively, unless the sintering aid component is added to enhance the sinterability, it is difficult to increase the density of the α-alumina sintered body. Therefore, in practice, it is better to use a sintered body in which the alumina crystal particles are slightly oriented on the c-axis from the viewpoint of increasing the density and strength of the α-alumina sintered body.

Moreover, when the value of the peak intensity ratio I ₀₀₆ / I ₁₁₀ of the surface and the cross section of the central portion of the α-alumina sintered body exceeds 0.07, the (006) plane in the α-alumina sintered body is obtained. This means that significant crystal grain orientation has occurred. Thus, when the orientation of alumina crystal grains to the (006) plane becomes stronger, the shrinkage direction, shrinkage rate, etc., compared with a portion having another orientation. The shrinkage behavior during firing is different. As a result, a stress is generated at the boundary portion of the portion having different shrinkage behavior inside the α-alumina sintered body. And this stress generation part exists in large numbers, especially as the sintered body is large, and as a result of the stress of these stress generation parts being concentrated particularly in the stress-concentrated part of the sintered body, The body will be cracked and damaged.

  In addition, with respect to a polycrystalline body made of an alumina sintered body or other ceramic material, the powder was subjected to X-ray diffraction measurement, and JCPDS (Joint Committee on Powder Diffraction) showing the ratio of peak intensity corresponding to each crystal plane. Standards) card, and in comparison with the JCPDS card, generally the crystal plane where each peak exists is identified.

Furthermore, a commercially available X-ray diffractometer may be used for the X-ray diffraction measurement, and the measurement results obtained from the measurement range of 0 ° to 90 ° by these devices are shown on the X-ray diffraction chart, and firstly, a JCPDS card is used. Then, the crystal phase of each peak displayed on the chart is identified. Then, after identifying crystal planes such as the (006) plane and the (110) plane only for the crystal peak of α-alumina and confirming the peak intensity values of the (006) plane and the (110) plane, the peak intensity ratio I A value of ₀₀₆ / I ₁₁₀ may be calculated. In this way, the peak intensity ratio I ₀₀₆ is also used for the surface of the α-alumina sintered body, the first cross section perpendicular to the surface, and the second cross section perpendicular to the surface and the first cross section using the same method. The value of / I ₁₁₀ may be calculated.

In particular, when a long α-alumina sintered body such as a rod, cylinder, plate or column is manufactured by a casting method, I ₀₀₆ / I ₁₁₀ is formed at the end of the sintered body. Therefore, it is important that the peak intensity ratio between the (006) plane and the (110) plane in the X-ray diffraction chart of the end surface and the cross section is in the range of 0.02 to 0.5. is there. The reason why the value of I ₀₀₆ / I ₁₁₀ increases at the end of the sintered body is not clear, but in the casting method, the slurry is used particularly in the vicinity of the filling port used when the slurry is filled in the non-water-absorbing mold. Pressure is applied, the alumina raw material particles in the slurry are easily oriented, and the slurry that has flowed into the mold at the end facing the filling port violently collides with the wall of the mold at the end, and the impact force during the collision is It is considered that since it is added to the slurry, an impact force acts on the alumina raw material particles in the slurry to facilitate orientation. In addition, the edge part of a sintered compact means the range about 20 mm from an end surface including an end surface.

Peak intensity ratio I between the (006) plane and the (110) plane in the X-ray diffraction chart of the surface and cross section of the end of the long α-alumina sintered body such as a rod, cylinder, plate or column _{If 006} / I ₁₁₀ is in the range of 0.02 to 0.5, the orientation of the crystal grains at the end of a long object having a length of 1 m or more in which the crystal grains are particularly easily oriented becomes irregular and occurs in the firing process. It is possible to suppress a difference in shrinkage rate between the end portions. Therefore, it is possible to suppress the occurrence of internal stress of the long object generated due to the difference in shrinkage rate, and it is possible to prevent the occurrence of cracks and breakage after the firing process of the long object considered to be caused by this internal stress. Therefore, a good alumina sintered body can be obtained.

On the other hand, when the value of I ₀₀₆ / I ₁₁₀ is less than 0.02, the crystal particles in the α-alumina sintered body are well dispersed in the direction other than the c-axis as in the case of the central portion described above. However, in such a state, the α-alumina primary raw material particles have a flat shape with a high aspect ratio, so that the contact area between the particles is larger than that of the oriented portion. Get smaller. When the contact area is reduced in this way, a constricted part called a neck is formed at the contact part between the particles, and a lot of heat energy is required for the development of this neck for sintering. Alternatively, unless the sintering aid component is added to enhance the sinterability, it is difficult to increase the density of the α-alumina sintered body. When the value of I ₀₀₆ / I ₁₁₀ exceeds 0.5, significant crystal grain orientation to the (006) plane occurs as in the case of the central portion. Thus, when the orientation of the alumina crystal particles to the (006) plane becomes stronger, the shrinkage behavior during firing, such as the shrinking direction and shrinkage rate, differs from that of the portion having other orientations. As a result, stress is generated at the boundary portion of the α-alumina sintered body where the shrinkage behavior is different, and if this acts on the stress-concentrated part or the low-strength part of the sintered body, the sintered body will crack. It will cause damage and damage.

Here, the reason why the upper limit of the value of I ₀₀₆ / I ₁₁₀ is different between the central portion of the α-alumina sintered body and the end portion of the long object is that the value of I ₀₀₆ / I _{110 in} the central portion. Since the stress generated by increasing acts on other parts except the central part in a wide range, it is necessary to reduce the setting of the upper limit value to suppress the occurrence of cracks and breakage. On the other hand, the orientation of the crystal grains tends to be larger at the end than at the center, but the stress generated at the end acts only in a narrow range in contact with the end. This is because cracks and breakage can be suppressed without lowering the setting.

In addition, the surface of an α-alumina sintered body produced by the production method of the present invention (hereinafter also simply referred to as the α-alumina sintered body of the present invention) , a first cross section perpendicular to the surface, the surface and the first 1 peak intensity of the X-ray diffraction chart of the vertical second section to the cross section (006) plane and the (110) plane ratio _I 006 _{/ I 110} is Ru der range of 0.02 to 0.07 both.

  Here, the surface of the α-alumina sintered body indicates the surface of the sintered body immediately after firing and the surface after processing, and the first cross section perpendicular to the surface is the surface of the sintered body immediately after firing or after processing. And a second cross section perpendicular to the surface and the first cross section refers to a surface immediately after firing or after processing and a plane perpendicular to the first cross section.

If the value of the peak intensity ratio I ₀₀₆ / I ₁₁₀ is calculated from the X-ray diffraction charts of these surfaces and the values of the three surfaces are all in the range of 0.02 to 0.07, It can be said that the orientation of the alumina crystal particles is good. In particular, when a large-sized thick product requiring no uniform orientation of alumina crystal particles in each part and requiring a uniform product is produced, it is possible to prevent the occurrence of cracks and breakage caused by partial application of internal stress.

When the value of the peak intensity ratio I ₀₀₆ / I ₁₁₀ of these three faces is less than 0.02, it is good in that the orientation of the alumina crystal particles is small and the variation in the orientation of the alumina crystal particles is small. Since the α-alumina primary raw material particles have a flat shape with a high aspect ratio, the contact area between the raw material particles is smaller than that of the oriented portion. When the contact area is reduced in this way, the α-alumina sintered body is not changed in the orientation of the alumina crystal particles unless firing is performed at a higher temperature or the sintering property is not increased by adding a sintering aid component. This is not preferable because it is difficult to increase the density uniformly. In addition, when the value of the peak intensity ratio I ₀₀₆ / I ₁₁₀ exceeds 0.07, significant crystal grain orientation to the (006) plane has occurred in the α-alumina sintered body. When the orientation of the alumina crystal particles to the (006) plane becomes stronger, the shrinkage behavior at the time of firing differs compared to the portion having other orientation, and stress is generated inside the α-alumina sintered body, This stress will cause cracks and breakage in the sintered body. In addition, the orientation of the alumina crystal particles to the (006) plane in the α-alumina sintered body is present with variation in each part of the α-alumina sintered body, Not only breakage, but also a difference in orientation between the surface and the cross section, and a crack or breakage due to stress generated between the partially oriented portions is likely to occur.

Furthermore, in the α-alumina sintered body of the present invention, it is preferable that the difference between the maximum value and the minimum value of the peak intensity ratio I ₀₀₆ / I ₁₁₀ of the surface and cross section of the central portion is within 0.05. This difference may be calculated by calculating the value of the peak intensity ratio I ₀₀₆ / I ₁₁₀ of each crystal plane as described above and obtaining the difference between the maximum value and the minimum value. When the difference between the maximum value and the minimum value exceeds 0.05, the variation in orientation to the (006) plane is partially large in the sintered body, and internal stress is applied to the alumina sintered body due to this variation. When this internal stress exceeds the strength of the alumina sintered body, the alumina sintered body as the final α-alumina sintered body will be cracked or damaged.

The α-alumina sintered body of the present invention is a long α-alumina sintered body having a rod-like shape, a cylindrical shape, a plate-like shape, a column-like shape, and the surface of the end portion and a surface perpendicular to the surface. The peak intensity ratio I ₀₀₆ / I ₁₁₀ between the (006) plane and the (110) plane in the X-ray diffraction chart of the first cross section and the second cross section perpendicular to the surface and the first cross section is in the range of 0.02 to 0.5. It is important to be within. Within this range, particularly at the end of the elongated object in which the crystal grains are easily oriented and the shrinkage rate is likely to vary, the surface and the first cross section perpendicular to the surface, as in the case of the above-mentioned central part, The orientation of the alumina crystal particles is good on both the surface and the second cross section perpendicular to the first cross section, and there is no orientation of the alumina crystal particles in each part. It can be a ligated body and can be free from cracks and breakage. When the value of I ₀₀₆ / I ₁₁₀ is less than 0.02, it is good in that the orientation of the alumina crystal particles is small and the orientation variation of the alumina crystal particles is small as in the case of the central portion described above. Since the α-alumina primary raw material particles have a flat shape with a high aspect ratio, the contact area between the raw material particles is smaller than when the α-alumina primary raw material particles are arranged with orientation. When the contact area is reduced in this way, a constricted part called a neck is formed at the contact part between the particles, and a lot of heat energy is required for the development of this neck for sintering. Alternatively, unless the sintering aid component is added to enhance the sinterability, it is difficult to increase the density of the α-alumina sintered body. When the value of I ₀₀₆ / I ₁₁₀ exceeds 0.5, significant crystal grain orientation to the (006) plane occurs in the α-alumina sintered body, and thus (006) When the orientation of the alumina crystal particles on the surface becomes stronger, the shrinkage behavior during firing differs compared to the portion with another orientation, and stress is generated inside the α-alumina sintered body, and this stress is Originally, the sintered body will be cracked or damaged. In addition, the orientation of the alumina crystal particles to the (006) plane in the α-alumina sintered body is present with variation in each part of the α-alumina sintered body, Not only breakage, but also a difference in orientation between the surface and the cross section, and a crack or breakage due to stress generated between the partially oriented portions is likely to occur.

Moreover, it is preferable that the α-alumina sintered body of the present invention contains a spinel crystal. The spinel crystal (MgAl ₂ O ₄ ) is an oxide that reacts with the Al component during firing when the Mg component originally contained as an inevitable impurity in the alumina primary raw material powder and the Mg component added as a sintering aid. It is formed and exists mainly at the grain boundaries of the α-alumina sintered body. When significant orientation occurs in the alumina crystal grains and internal stress is generated, this internal stress acts on the grain boundaries of the α-alumina sintered body, so first, some of the grain boundaries are cracked. . And the grain-boundary fracture which a crack propagates from the part to a grain boundary occurs, and this finally becomes the crack and breakage of the α-alumina sintered body. On the other hand, if a spinel crystal is formed at the grain boundary as in the α-alumina sintered body of the present invention, the spinel crystal mainly exists independently at the grain boundary. Propagation of cracks from grain boundaries to grain boundaries can be prevented, and cracks and breakage can be more effectively prevented.

Furthermore, the α-alumina sintered body of the present invention preferably has a purity of 90% or more and a density of 3.8 g / cm ³ or more. When the purity is less than 90%, the orientation of alumina crystal particles occurs in the α-alumina sintered body, and internal stress that leads to cracking or breakage of the sintered body occurs. The impurity layer that relaxes mitigates the influence of this internal stress and makes it difficult for cracks and breakage to occur. Accordingly, the problem of cracks and breakage due to internal stress generated in the sintered body due to the orientation of the alumina crystal particles is less than that having a purity of less than 90%, and the necessity for controlling the orientation of the crystal particles is reduced. Therefore, the present invention is suitable for an α-alumina sintered body having a purity of 90% or more. Further, in the sintered body having a density of less than 3.8 g / cm ³ , many voids exist in the sintered body. Like the above-mentioned spinel crystal, the voids prevent cracks and breakage from occurring in order to prevent propagation of cracks occurring in the sintered body. Therefore, there is little problem of cracking or breakage due to stress generated in the sintered body due to the orientation of the alumina crystal particles when the density is less than 3.8 g / cm ^3, and there is little need to control the orientation of the crystal particles. Therefore, the present invention is suitably used for an α-alumina sintered body having a density of 3.8 g / cm ³ or more.

  Next, the manufacturing method of the alumina sintered body of the present invention will be described in detail.

The production method of the α-alumina sintered body of the present invention comprises α-alumina primary raw material particles having an average particle size of 0.5 to 2.0 μm and a particle shape ratio of 1.5 to 2.0, a binder, a dispersant, and a solvent. By mixing, a solidified or curable slurry having a particle volume fraction of α-alumina primary raw material particles of 25 to 45% by volume is injected, and this slurry is poured into a non-liquid-absorbing mold. This is a casting molding method (gel casting method) characterized by firing the α-alumina molded body after obtaining a quality molded body. As a sintering aid, magnesia (MgO), silica (SiO ₂ ), and calcia (CaO) used for general ceramic production may be added.

  Here, the average particle size of the α-alumina primary raw material particles is in the range of 0.5 to 2.0 μm because the average particle size of less than 0.5 μm has a fine particle size and the total surface area of the powder (ratio) This is because the surface area) becomes large, and good fluidity of the slurry cannot be ensured unless the amount of solvent, binder and dispersant used in preparing the slurry is increased. Solvents, binders, and dispersants are components that burn out during firing, and a large amount of these is preferable because the shrinkage rate during drying and firing increases, and the molded body and sintered body tend to be deformed and damaged. Absent. On the other hand, an average particle size exceeding 2.0 μm is not preferable because it is difficult to sinter and it becomes difficult to densify.

  In addition, the particle size ratio of the α-alumina primary raw material particles is taken as an SEM (scanning electron microscope) photograph of the α-alumina primary raw material, and 10 particles are arbitrarily selected from the SEM photographic image. The maximum length of each particle is taken as the major axis L, the maximum length in the direction perpendicular to the major axis L is taken as the minor axis S, and the L / S value is calculated and averaged. The reason why the particle size ratio is in the range of 1.5 to 2.0 is that when the particle shape ratio exceeds 2.0, it is not preferable that the particles are easily oriented along the flow of the slurry. In addition, it is preferable to use spherical particles, that is, particles having a particle size ratio of 1 to suppress the orientation of the particles, but particles having a particle shape ratio of 1 are difficult to obtain in practice, and the raw material unit price is extremely high. . Therefore, it can be said that the lower limit of the particle shape ratio obtained at low cost is about 1.5.

  Furthermore, as the solvent constituting the slurry, either an aqueous system or an organic system can be used. When an organic solvent is used, paraffin, isoparaffin, toluene, xylene, petroleum, ether, or the like can be used. However, considering the safety in the handling of the slurry and the drying process, it is more preferable to use water as the solvent. The addition amount of the solvent is preferably in the range of 10 to 30% by mass with respect to 100% by mass of the α-alumina primary raw material.

  As the binder, an emulsion binder is used for solidifying or curing the slurry. The binder in the emulsion state includes various copolymers obtained from styrene, butadiene, isobrene, (meth) acrylonitrile, acrylamide, ethylene, vinyl acetate, acrylic resin, etc., and multi-copolymers with unsaturated carboxylic acids or dicarboxylic acids. Coalescence can be used. In addition, as addition amount of a binder, it is suitable to set it as the inside of the range of 10-30 mass% with respect to 100 mass% of alpha-alumina primary raw materials.

  Moreover, as a dispersing agent, it is possible to use a nonionic compound, an anionic compound, and a cationic compound, and it is also possible to use these 1 or more types of dispersing agents simultaneously. The dispersant lowers the interfacial tension between the raw particles, improves wettability, controls the charge on the particle surface, and forms a thick and stable adsorption layer on the particle surface, thus reducing the van der Waals force between the particles. It is thought that the effect of being able to contribute to the improvement in the freedom degree in the slurry of the raw material particle | grains is provided with the repulsive force which prevails. In the present invention, due to the effect of the dispersant, the degree of freedom of movement of the α-alumina primary raw material particles in the slurry can be improved, so that the orientation of the alumina crystal particles does not occur after firing. In addition, as addition amount of a dispersing agent, it is suitable to add within the range of 0.01-1 mass% with respect to 100 mass% of alpha-alumina primary raw materials.

  In addition, the particle volume fraction of the α-alumina primary raw material particles in the slurry is 25 to 45% by volume. If it is less than 25% by volume, there are too few particles in the slurry and the slurry is solidified or cured. When the resin is taken out from the mold and dried, the shrinkage in the drying process increases, and the deformation of the molded body increases, which is not preferable. On the other hand, when it exceeds 45 volume%, the distance between the raw material particles in the slurry is shortened, and the freedom of movement of the raw material particles in the slurry is remarkably reduced. For this reason, when the slurry is filled into the mold, the raw material particles are easily oriented along the flow of the slurry, and adjacent raw material particles influence each other, and the van der Waals force also helps, in the vicinity of the oriented raw material particles. Other raw material particles are not preferable because it is considered that the particles are likely to be oriented in the same direction.

  As described above, the α-alumina primary raw material particles cause the particle arrangement along the flow of the slurry that becomes the orientation of the alumina crystal particles after firing by the function of the dispersant and the control of the particle volume fraction. Therefore, if an α-alumina sintered body is produced using such a slurry, a product in which the orientation of the alumina crystal particles is suppressed can be produced.

  Furthermore, the viscosity of the slurry is preferably 0.02 to 0.5 Pa · s. This slurry viscosity is easily influenced by the particle volume fraction in the slurry, and is also easily influenced by the contents of the solvent, binder and dispersant, and these must be adjusted within an appropriate range. When the slurry viscosity is lower than 0.02 Pa · s, the amount of solvent or the like increases, the particle volume fraction in the mold decreases, and it becomes difficult to increase the density of the molded body. Moreover, since the drying shrinkage in the drying process after solidification of the slurry becomes large, the molded article after drying tends to be cracked or damaged. If it is higher than 0.5 Pa · s, not only will it be difficult to fill the slurry into the non-absorbing mold, but also when the slurry is filled into the mold, the filled slurry will have a uniform flow in each part of the mold. This is not preferred because the orientation of the alumina crystal particles is likely to occur.

  In the method for producing an alumina sintered body of the present invention, a non-liquid-absorbing mold is used as a mold for injecting slurry. If the mold is non-liquid-absorbing, there is no problem such as clogging that occurs when using the liquid-absorbing mold used in the conventional casting molding method, and the life of the mold is extended. As the material of the non-liquid-absorbing mold, any material can be used as long as it has non-liquid-absorbing characteristics, such as metal, resin, and wood. In particular, in the production method of the present invention, it is more preferable to use a metal mold from the viewpoint of dimensional accuracy, ease of taking out the solidified body after solidifying the slurry, and thermal conductivity during heating. As specific metal mold materials, aluminum, an aluminum alloy, titanium, a titanium alloy, a magnesium alloy, and the like are good because they are lightweight and have sufficient strength and heat resistance.

  Furthermore, it has already been described that the alumina sintered body and the method for producing the same of the present invention are particularly effective for large products. However, when the large products are represented by the size of a mold, at least one of the inner surfaces is 10 mm. This is particularly effective when applied to a material having the above width and a length of 1500 mm or more.

  Moreover, the slurry used for the manufacturing method of the alumina sintered body of this invention has a solidification property or sclerosis | hardenability. When solidifying the slurry in a non-liquid-absorbing mold using this solidifying or curable slurry, the mold is heated to 50 to 100 ° C. to change the temperature of the slurry in the mold, The emulsion state of the binder in the emulsion state is broken by the action of the dispersant. When the emulsion state is destroyed, the binders or the binder and the raw material particles are combined by van der Waals force or hydrogen bond, and solidified into an agar-like form containing a solvent. After solidification, the solidified body is taken out from the mold, and the solidified body is heated at 120 to 200 ° C. Thereby, a solvent component evaporates from a solidified body, and it hardens | cures, and becomes a ceramic molded body.

  Thereafter, this molded body is fired at a maximum temperature of 1550 to 1700 ° C. in a firing furnace, whereby the α-alumina sintered body of the present invention can be obtained. About the obtained (alpha) -alumina sintered compact, it can grind as needed and can be processed into a predetermined shape.

  The α-alumina sintered body of the present invention thus produced can be applied to various products. Particularly in recent years, in the field of semiconductor or liquid crystal manufacturing equipment where there is a high demand for large-sized products, a semiconductor or liquid crystal manufacturing apparatus having a length of 2 m or more, for example, which has been conventionally adapted to increase in size by engaging a small size. By using the method for producing an α-alumina sintered body according to the present invention, it is possible to produce a stage member integrally without any defects such as cracks and breakage. It is possible to contribute to manufacturing.

  As mentioned above, although the example of embodiment of this invention was demonstrated, it cannot be overemphasized that it can apply also to what gave the various improvement and change, if it is a range which does not deviate from the summary of this invention. In particular, regarding the shape of the α-alumina sintered body, the orientation of the alumina crystal particles can be incorporated into the sintered body if it is applied to a large and complicated shape suitable for applications other than the semiconductor or liquid crystal manufacturing apparatus stage member. Since it is possible to eliminate the occurrence of internal stress that leads to cracks and breakage, good product production is possible.

  Examples of the present invention will be described below.

Example 1
In the production of the α-alumina sintered body of the present invention by a casting method (gel casting method), a test for confirming the influence of the particle shape ratio was performed.

  First, in order to confirm the influence of the particle shape ratio, five commercially available α-alumina primary raw materials having a particle shape ratio shown in Table 1 and having a purity of 99% and an average particle diameter of 1 μm were prepared. In addition, since the alumina primary raw material with a particle size ratio of less than 1.5 has a remarkably high raw material unit price, a material with a particle shape ratio of 1.5 or more was prepared.

  Next, for each of the five types of α-alumina primary materials, the solvent is 15% by mass, the binder is 15% by mass, the dispersant is 0.5% by mass, and the crosslinking agent is 0.5% by mass with respect to 100% by mass of the α-alumina raw material. % And a sintering aid were added in a predetermined amount and charged into a universal mixing stirrer and mixed to prepare five types of molding slurries. Here, water was used as the solvent, and an acrylic resin emulsion binder was used as the binder. Further, as the dispersant, a mixture of nonionic, anionic, and cationic compounds in a predetermined ratio was used, and an acrylic resin-based crosslinking agent was added thereto in accordance with the binder. Furthermore, the particle volume fraction in the slurry was 35% by volume, and the slurry viscosity was 0.1 Pa · s as measured with a commercially available E-type viscometer.

  Next, this slurry was filled in a mold. As the mold, a mold having a dimension capable of forming a long plate having a width of 200 mm, a length of 1000 mm, and a thickness of 30 mm was used, and the slurry was filled from a slurry filling port provided at an end of the mold. After filling, the filling port was closed so that the slurry did not flow out of the slurry filling port, and then the mold was heated to 70 ° C. to solidify (gelate) the slurry. Then, the solidified solid body was taken out from the mold, put into a large dryer and dried, and the solvent was evaporated to obtain a molded body.

  Thereafter, this compact is fired at a maximum temperature of 1650 ° C. in a firing furnace, and subjected to grinding, and sample No. of an α-alumina sintered body having a width of 150 mm, a length of 750 mm, and a thickness of 20 mm. . 1-5 were manufactured.

  Next, in order to confirm the presence or absence of cracks or breakage in the surface or cross section of the α-alumina sintered body, each sample was immersed in a color check solution stored in a large water tank. At the time of immersion, the α-alumina sintered body was divided into two so that the cross section could be confirmed. If there is a crack or breakage on the surface or cross section of the sintered body, the color check solution will soak into that part and the presence or absence of cracks or breakage can be confirmed visually.

Next, the color check solution attached to the surface of the α-alumina sintered body is thoroughly washed out using the cleaning liquid, and then dried, and the surface of the central portion of the α-alumina sintered body and the X-ray of the cross section are cross-sectioned. Diffraction measurement was performed, and the peak intensity ratio I ₀₀₆ / I ₁₁₀ between the (006) plane and the (110) plane was calculated from the X-ray diffraction chart.

Table 1 shows the results of these appearance inspections and the calculation results of the peak intensity ratio I ₀₀₆ / I ₁₁₀ from the X-ray diffraction chart. As for the appearance inspection results, those with no cracks and breakage were shown as good, and those with cracks were shown as bad.

As shown in Table 1, Sample No. which is outside the scope of the present invention. For No. 4, the value of I ₀₀₆ / I ₁₁₀ is as high as 0.08 because the particle shape ratio is as large as 2.1. For this reason, internal stress was generated in the α-alumina sintered body, and this caused many fine cracks in the surface and cross section of the central portion of the sintered body.

  Furthermore, sample no. No. 5 has a large particle shape ratio of 2.5. The α-alumina sintered body was damaged by a crack larger than 4.

  Compared with these, sample No. within the scope of the present invention. About 1-3, it was confirmed that there is no crack or breakage in the surface or cross section of the α-alumina sintered body and it is good.

(Example 2)
Next, five types of α-alumina primary raw materials having different particle size ratios as in Example 1 were used, and a columnar body having a square shape with a length of 1000 mm and a cross section of 200 mm by the same manufacturing method. An α-alumina sintered body was produced.

  Then, the columnar α-alumina sintered body was immersed in a color check solution stored in a large water tank, and the presence or absence of cracks or breakage was particularly confirmed at the end. Further, it was divided into two at a portion of 10 mm from the end face, and dipped again in the color check solution to confirm the presence or absence of cracks or damage inside the end part.

Next, X-ray diffraction measurement was performed on the surface and cross section of a 10 mm-thick divided sample cut from the end of the columnar α-alumina sintered body. From the X-ray diffraction chart, the (006) plane and The peak intensity ratio I ₀₀₆ / I ₁₁₀ with the (110) plane was calculated.

Table 1 shows the results of these appearance inspections and the calculation results of the peak intensity ratio I ₀₀₆ / I ₁₁₀ from the X-ray diffraction chart. As for the appearance inspection results, those with no cracks and breakage were shown as good, and those with cracks were shown as bad.

As shown in Table 2, Sample No. which is outside the scope of the present invention. For No. 9, since the particle size ratio is as large as 2.1, the value of I ₀₀₆ / I ₁₁₀ is high. For this reason, internal stress is generated in the α-alumina sintered body, and due to this internal stress, many fine cracks are confirmed in the surface and cross section of the end portion of the α-alumina sintered body by the appearance inspection, It turned out that the same tendency as Example 1 is shown.

  Furthermore, sample no. 10 has a large particle size ratio of 2.5. It was confirmed that a crack larger than 9 occurred in the end portion, and it was confirmed that this also showed the same tendency as that in the central portion of Example 1.

  Compared with these, sample No. within the scope of the present invention. About 6-8, it was confirmed that there is no crack or damage in the surface or cross section of the edge part of (alpha) -alumina sintered compact.

(Example 3)
Next, a larger product was manufactured using five kinds of α-alumina primary raw materials having different particle size ratios as in Example 1. As a manufacturing method, it is the same as that of Example 1, and the difference is that the mold used has a width of 600 mm, a length of 3000 mm, and a thickness of 70 mm, and the final α-alumina sintered body has a shape of This is a long plate-like body having a width of 450 mm, a length of 2300 mm, and a thickness of 50 mm. These long plate-like bodies are referred to as Sample No. 11-15.

For the X-ray diffraction measurement after production of the α-alumina sintered body, Sample No. First, the sintered bodies of 11 to 15 are divided in the length direction perpendicular to the surface to make the cross section perpendicular to the surface the first cross section, and further divided perpendicularly to the surface and the first cross section to make this cross section the second cross section. A cross section. Next, for these samples, the surface, the first cross section, and the second cross section were measured by X-ray diffraction, and the value of the peak intensity ratio I ₀₀₆ / I ₁₁₀ was calculated from the X-ray diffraction chart.

  Further, for the appearance inspection, the divided sample was immersed in a color check solution, and as in Example 1, it was confirmed whether the surface or the cross section was free from cracks or breakage.

In Table 3, sample No. The values of the peak intensity ratio I ₀₀₆ / I ₁₁₀ of 11 to 15 and the results of the appearance inspection are shown. As for the appearance inspection results, those with no cracks and breakage were shown as good, and those with cracks were shown as bad.

According to the results shown in Table 3, Sample No. As for Example 14, as in Example 1, cracks occurred on the surface, the first cross section, and the second cross section in the appearance inspection. The peak intensity ratio I ₀₀₆ / I ₁₁₀ also showed a good value on the surface and the second cross section, but 0.08 on the first cross section, a value outside the range of the present invention. This is because arrangement of α-alumina primary raw material particles along the flow direction of the slurry occurs on this surface, which causes the orientation of the alumina crystal particles of the sintered body, and the shrinkage direction between this surface and the other surface. It is considered that the difference in shrinkage rate caused stress in the sintered body, which led to the occurrence of cracks.

Sample No. Regarding No. 15, the orientation of large alumina crystal particles was confirmed especially in the second cross section. Compared to 14, not only cracks but also damage to the sintered body occurred. This is the sample No. For No. 15, the difference between the maximum value and the minimum value of the peak intensity ratio I ₀₀₆ / I ₁₁₀ showed a large value of 0.29. Therefore, particularly large internal stress that would cause breakage in the sintered body Is considered to have occurred.

  Compared with these, sample No. About 11-13, it was confirmed that there is no generation | occurrence | production of a crack and damage in the surface, 1st cross section, and 2nd cross section of (alpha) -alumina sintered compact, and a favorable sintered compact is obtained. From this, it can be said that the particle shape ratio of the α-alumina primary raw material particles has a great influence on the orientation of the alumina crystal particles of the α-alumina sintered body.

Example 4
Next, α-alumina primary raw materials having five different particle shape ratios as in Example 1 were used, and the outer diameter was 300 mm, the inner diameter was 15 mm, and the length was the same as in Example 1. A 2000-mm cylindrical α-alumina sintered body was produced. 16-20.

  Then, the cylindrical α-alumina sintered body was divided perpendicularly to the surface at a portion 10 mm from the end, and this cross section was defined as a first cross section. Further, the surface and the first cross section were divided vertically, and the cross section was defined as the second cross section.

Next, X-ray diffraction measurement was performed on the surface, first cross section, and second cross section of the sample, and the value of the peak intensity ratio I ₀₀₆ / I _{110 at} the end was calculated from the diffraction chart.

Further, for the appearance inspection, the divided samples were immersed in a color check solution, and in the same manner as in Example 1, the presence or absence of cracks or breakage was confirmed on the surface or the cross section.

According to the results shown in Table 4, sample No. For 19, since the particle shape ratio is as large as 2.1, the value of the peak intensity ratio I ₀₀₆ / I ₁₁₀ in the second cross section is as high as 0.56. For this reason, it is thought that a big internal stress arises in a sintered compact. Furthermore, the variation of the value of I ₀₀₆ / I _{110 on} the surface, the first cross section, and the second cross section is large, and the difference between the maximum value and the minimum value is as high as 0.55. Due to this influence, the difference in shrinkage rate during sintering was large, and many fine cracks were observed at the end portion in the appearance inspection.

In addition, sample No. outside the scope of the present invention. For sample 20, sample no. Since the maximum value of I ₀₀₆ / I ₁₁₀ is larger than 19 and the difference between the minimum value and the maximum value is as large as 0.95, not only fine cracks but also damage to the ends of the cylindrical body are observed in appearance inspection As a result.

  Compared with these, sample No. within the scope of the present invention. In the case of 16 to 18, no crack or breakage was observed at the end of the cylindrical body in the appearance inspection.

(Example 5)
Next, sample no. Using the same α-alumina primary raw material and mold as in No. 1, a test for confirming the influence of the particle volume fraction in the slurry was conducted.

  The test was carried out using the same production method as in Example 1, and the particle volume fraction was adjusted as shown in Table 5 by changing only the content of the α-alumina primary raw material in the slurry.

Further, the X-ray diffraction measurement of the sintered α-alumina sintered body was carried out in the same manner as in Example 1. From the X-ray diffraction chart, the peak intensity ratio between the (006) plane and the (110) plane was measured. I ₀₀₆ / I ₁₁₀ was calculated.

Further, the appearance inspection was also performed in the same manner as in Example 1, and the results are shown in Table 5. As for the appearance inspection results, those with no cracks and breakage were shown as good, and those with cracks were shown as bad.

According to the results shown in Table 5, sample nos. As for No. 21, although the value of the peak intensity ratio I ₀₀₆ / I ₁₁₀ of the surface or cross section is within the range, the particle volume fraction is too small, so that the solvent, the binder, the dispersant, and the crosslinking agent are burned out. The accompanying deformation amount was large, and a crack was generated on a part of the surface of the sintered body. In addition, since the particle volume fraction is too small and the contact area between the alumina particles is small, it is difficult to sinter. For this reason, the sintered body has a lower density than other samples. It is thought that the physical characteristics have deteriorated.

  In addition, sample No. outside the scope of the present invention. Regarding No. 27, the difference in the orientation of the alumina crystal particles between the sintered body surface and the cross section is large, and the orientation of the alumina crystal particles particularly in the c-axis is recognized in the cross section. For this reason, generation | occurrence | production of the crack was seen in the sintered compact and it has reached to the damage. This is because the particle volume fraction in the slurry is high and the degree of freedom of the particles in the slurry is extremely small, so that the orientation of the alumina crystal particles occurs in a part of the sintered body, and the α-alumina sintered body It is considered that the orientation of the alumina crystal particles that generate a large internal stress that leads to cracks and breakage occurred.

  Compared with these, sample No. within the scope of the present invention. For 22 to 26, it was confirmed that a good α-alumina sintered body could be produced without cracks or breakage.

(Example 6)
Next, a larger product than Example 5 was manufactured, and a test for confirming the influence of the particle volume fraction in the slurry was performed.

  In the test, the α-alumina sintered body was produced by the same method as in Example 5, and only the molding die filled with the slurry was used using the large molding die used in Example 3.

The evaluation method used was almost the same as in Example 5. However, the X-ray diffraction measurement surface of the α-alumina sintered body was divided by the same method as in Example 3. The peak intensity ratio I ₀₀₆ / I ₁₁₀ between the (006) plane and the (110) plane was calculated for the surface, the first cross section, and the second cross section.

Further, the appearance inspection was also performed in the same manner as in Example 1, and the results are shown in Table 6. As for the appearance inspection results, those with no cracks and breakage were shown as good, and those with cracks were shown as bad.

According to the results shown in Table 6, the sample No. For the samples 28 and 29, the value of the peak intensity ratio I ₀₀₆ / I ₁₁₀ of the surface or cross section is within the range as in the case of Example 5, but the particle volume fraction is small. The amount of deformation caused by burnout of the dispersant and the cross-linking agent was large, and cracks occurred on part of the surface of the sintered body. In addition, since the particle volume fraction is too small and the contact area between the alumina particles is small, it is difficult to sinter. For this reason, the sintered body has a lower density than other samples. It is thought that the physical characteristics have deteriorated.

In addition, sample No. outside the scope of the present invention. As for 35, the surface value, the value of the second cross section, and the value of the maximum value-minimum value are good, but the value of I ₀₀₆ / I ₁₁₀ of the first cross section is out of the range. Internal stress was generated and cracks occurred.

Sample No. For 36, the value of the surface and the second cross section is out of the range, and the difference between the maximum value and the minimum value of the peak intensity ratio I ₀₀₆ / I ₁₁₀ shows a large difference of 0.16. In the product, it is considered that a large internal stress is generated in the sintered body, which leads to breakage.

  Compared with these, sample No. which is within the scope of the present invention. For 30 to 34, it was confirmed that a good α-alumina sintered body could be produced even in a large product without cracking or breakage in the α-alumina sintered body.

  From this, in the production method of the present invention, it was confirmed that the particle volume fraction in the slurry greatly affects the orientation of the alumina crystal particles of the α-alumina sintered body.

(Example 7)
Next, sample no. The average particle shape of the α-alumina primary raw material having the same particle shape ratio as that of Example 1 was variously changed. As the particle volume fraction in the same slurry as 24, an α-alumina sintered body having the same shape as in Example 5 was produced by the same production method.

  In addition, in order to confirm the deformation | transformation of the alpha alumina sintered body accompanying the change of an average particle diameter, the curvature deformation amount was measured on the surface plate.

Furthermore, the appearance inspection was also performed in the same manner as in Example 1, and the results are shown in Table 7. As for the appearance inspection results, those with no cracks and breakage were shown as good, and those with cracks were shown as bad.

  According to the results shown in Table 7, the sample No. using the α-alumina primary material having an average particle diameter outside the range of the present invention was used. As for 37, there was no orientation of the alumina crystal particles of the α-alumina sintered body, and it was sufficiently densified, but the warpage deformation amount of the α-alumina sintered body was large, and the α-alumina sintered body Cracks occurred on the body surface.

  In addition, sample No. outside the scope of the present invention. Regarding No. 42, although there was no orientation of the alumina crystal particles and the amount of deformation was small, it was difficult to sufficiently densify.

  Compared with these, sample No. within the scope of the present invention. As for 38 to 41, it was confirmed that it is possible to produce an α-alumina sintered body that is sufficiently densified and has a small amount of deformation without orientation of alumina crystal particles.

  From these test results, not only small alumina sintered bodies but also molded bodies obtained with the conventional manufacturing method can not be made into products due to cracks and breakage in the sintered body after firing. A large-sized alumina sintered body is mixed with α-alumina primary raw material particles having an average particle size of 0.5 to 2.0 μm and a particle size ratio of 1.5 to 2.0, a binder, a dispersant, and a solvent. , Α-alumina primary raw material particles are solidified or curable slurry with a volume fraction of 25 to 45% by volume, and this slurry is poured into a non-liquid-absorbing mold to form an α-alumina molded body. After obtaining the above, it was confirmed that the α-alumina shaped body can be produced by firing. And this alumina sintered body can be used suitably for the stage member for semiconductor or a liquid crystal manufacturing apparatus.

It is an X-ray diffraction chart which shows an example of the X-ray-diffraction measurement result of the alpha-alumina sintered compact produced by the manufacturing method of this invention.

Claims (5)

The alumina sintered body in which the peak intensity ratio I ₀₀₆ / I ₁₁₀ between the (006) plane and the (110) plane in the X-ray diffraction chart of the center surface and cross section is in the range of 0.02 to 0.07. Α-alumina primary raw material particles having an average particle size of 0.5 to 2.0 μm and a particle shape ratio of 1.5 to 2.0, an emulsion binder, a dispersant, a solvent, and a production method The α-alumina primary raw material particles have a volume fraction of 25 to 45% by volume , solidified or curable, and a slurry having a viscosity of 0.02 to 0.5 Pa · s , Is poured into a non-liquid-absorbing mold, the mold is heated to 50 to 100 ° C. to break the emulsion state of the binder to produce a solidified body, and the solidified body is taken out from the mold. The solvent component is evaporated and cured by heating, and α- After obtaining the alumina electrolyte molded body, method for manufacturing the alumina sintered body and firing the α- alumina formed body. In the X-ray diffraction chart of the end surface and cross section, the peak intensity ratio I ₀₀₆ / I ₁₁₀ between the (006) plane and the (110) plane is in the range of 0.02 to 0.5, rod-shaped, cylindrical, A method for producing a plate-like, columnar, etc. long alumina sintered body having an average particle size of 0.5 to 2.0 μm and a particle shape ratio of 1.5 to 2.0 Alumina primary raw material particles, an emulsion binder, a dispersant, and a solvent are mixed to make the volume fraction of the α-alumina primary raw material particles 25 to 45% by volume , solidifying or curable, and having a viscosity. Is made into a slurry of 0.02 to 0.5 Pa · s, the slurry is poured into a non-liquid-absorbing mold, and the mold is heated to 50 to 100 ° C. to destroy the emulsion state of the binder. A solidified body is prepared, and the solidified body is taken out from the mold and heated. After the serial solvent component was obtained evaporation cured α- alumina formed body, the manufacturing method of the alumina sintered body and firing the α- alumina formed body. Peak intensity ratio I ₀₀₆ / of (006) plane and (110) plane in the X-ray diffraction chart of the central surface, the first cross section perpendicular to the surface, and the second cross section perpendicular to the surface and the first cross section I ₁₁₀ is a method for producing an alumina sintered body in which all are in the range of 0.02 to 0.07, the average particle size is 0.5 to 2.0 μm, and the particle shape ratio is 1.5 to 2.0 in some by mixing the dispersing agent and a solvent with a binder of α- alumina primary raw material particles and an emulsion state, the particle volume fraction of the α- alumina primary raw material particles and 25 to 45 vol%, solidification Or a curable slurry having a viscosity of 0.02 to 0.5 Pa · s , injecting the slurry into a non-liquid-absorbing mold, and heating the mold to 50 to 100 ° C. A solidified body is produced by breaking the emulsion state of The solidified body is taken out and heated to evaporate and cure the solvent component to obtain an α-alumina molded body, and then the α-alumina molded body is fired. Method. The peak intensity ratio I ₀₀₆ / of the (006) plane and the (110) plane in the X-ray diffraction chart of the end surface, the first cross section perpendicular to the surface, and the second cross section perpendicular to the surface and the first cross section. I ₁₁₀ is a method for producing an alumina sintered body having a long shape such as a rod, tube, plate, column, etc., each having an average particle size of 0. Α-alumina primary raw material particles having a particle size ratio of 1.5 to 2.0, a binder in a state of emulsion, a dispersant, and a solvent are mixed, and the α-alumina primary is mixed. The raw material particles have a particle volume fraction of 25 to 45% by volume , a solidified or curable slurry having a viscosity of 0.02 to 0.5 Pa · s , and the slurry is poured into a non-liquid-absorbing mold. The mold is heated to 50 to 100 ° C. to destroy the emulsion state of the binder. A solidified body is prepared, the solidified body is taken out from the mold and heated to evaporate and cure the solvent component to obtain an α-alumina molded body, and then the α-alumina molded body is fired. A method for producing an alumina sintered body.   The alumina sintered body according to any one of claims 1 to 4, wherein at least one of the inner surfaces of the mold has a width of 10 mm or more and a length of 1500 mm or more. Production method.

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