JP2007254276A - Alumina sintered body, manufacturing method thereof, and liquid crystal manufacturing apparatus using the same - Google Patents

Abstract

Alignment of alumina particles in a large-sized liquid crystal production apparatus member made of an alumina sintered body having a length of 100 mm or more, a length of 2 m or more, and a thickness of 20 mm or more manufactured by a gel casting method There was a problem that cracks and breakage occurred due to shrinkage variations during firing due to the above.
A substantially rectangular parallelepiped alumina sintered body having a length of 2000 mm or more, a width of 100 mm or more, and a thickness of 20 mm or more, and a peak intensity ratio of X-ray diffraction at the central portion of the main surface in the longitudinal direction {(006) Plane / (110) plane} and the X-ray diffraction peak intensity ratio {(006) plane / (110) plane} at the end of the main surface in the longitudinal direction are 0.01 to 0.00 mm in absolute value. Be 15.
[Selection] Figure 1

Description

  The present invention relates to an alumina sintered body, a production method thereof, and a liquid crystal production apparatus using the same.

  In response to the recent increase in the screen size of liquid crystal televisions, glass substrates for liquid crystal production have been increased in area from the viewpoint of production efficiency and have reached a size with a long side exceeding 2 m. Along with this, liquid crystal manufacturing apparatuses that handle glass substrates have been increasing in size, and there is an increasing demand for increasing the size of the bar mirror and end effector, which are structural parts of the liquid crystal manufacturing apparatus, with a long side exceeding 2 m. A bar mirror for a liquid crystal manufacturing apparatus is a component used for positioning of an exposure apparatus, and an end effector is used as a support for supporting the glass substrate during conveyance of the glass substrate.

  As a molding method for these large ceramic parts, a cast molding method has recently been spotlighted as a molding method for obtaining a molded body that is inexpensive and safely close to the product shape. Specifically, it is a gel casting method using a thermosetting resin as a binder. The gel casting method is a kind of cast molding method developed around 1990, and is a molding method in which a non-water-absorbent mold is filled with a slurry added with a thermosetting resin as a binder and then cured. However, in the gel casting method using a thermosetting resin or a slurry added with an initiator so as to be cured at room temperature, there is about 1 to 2% shrinkage accompanying the curing of the resin. It has been found that dimensional shrinkage cannot be ignored and is inadequate for manufacturing complex shapes and large products.

  Therefore, in order to solve the problem of dimensional shrinkage during molding, the present inventors have developed a new gel casting technique that uses an emulsion as a binder and solidifies by breaking this emulsion, and the problem of dimensional shrinkage during molding. As a result, complex shapes such as hollow shapes and large ceramic parts can be manufactured.

  However, the problem that various cracks and breakages occur in the ceramic sintered body used for the ceramic component due to the firing shrinkage that occurs in the subsequent firing step has been clarified.

In order to solve such a problem, Patent Document 1 has a description suggesting that particle orientation occurs in the molded body due to the shape of the alumina particles, which causes cracks in the sintered body.
JP 09-255413 A

  In Patent Document 1, regarding the orientation of alumina particles in the above-mentioned molded body, the (104) plane assignment is the main peak in the X-ray diffraction of alumina also shown in the JCPDS card from the X-ray diffraction result of the surface of the molded body. Focusing on the peak intensity and the (030) plane attribute peak intensity, if it is a molded body in which these relationships are within a certain range, a β-alumina tube free from cracks and breakage after firing can be produced.

  However, the above technique is a technique that can be applied only when a relatively thin-walled tubular molded body is manufactured by a press molding method, and cannot be applied when a large-sized alumina structure is manufactured by a casting molding method.

  The present inventors have found that alumina sintered bodies that have been cracked or damaged by various analyzes have a structure in which the alumina particles are oriented in a complicated manner when the slurry is poured into a mold during casting. It was ascertained that the orientation that causes cracks and breakage occurred.

  In other words, in the casting method, alumina powder, binder, dispersant, and water are mixed to form a slurry, which is then poured into the casting mold. At this time, the slurry flows due to friction with the molding die at each part of the mold. However, when an alumina structure is produced by drying and firing, alumina particles are arranged along the direction of the slurry flow, and orientation of the alumina crystal particles occurs. And if each part has different crystal orientation, it shrinks mainly due to the evaporation of moisture in the slurry during drying, so a molded product can be manufactured without problems of cracks and breakage. Then, the firing shrinkage accompanying the alumina crystal growth occurs, and different shrinkage behaviors are exhibited in each part in the same sintered body, so that the sintered body is cracked or broken.

  An object of the present invention is to provide a large-sized alumina sintered body capable of reducing the different shrinkage behavior in each part of the same sintered body as described above and a method for producing the same.

  In view of the above problems, the alumina sintered body of the present invention is a substantially rectangular parallelepiped alumina sintered body having a length of 2000 mm or more, a width of 100 mm or more, and a thickness of 20 mm or more, and X in the central portion of the main surface in the longitudinal direction. The difference between the peak intensity ratio {(006) plane / (110) plane} of the line diffraction and the peak intensity ratio {(006) plane / (110) plane} of the X-ray diffraction at the end of the main surface in the longitudinal direction is The absolute value is 0.01 to 0.15.

  Further, the peak intensity ratio {(006) plane / (110) plane} of the X-ray diffraction in the central portion of the main surface in the longitudinal direction and the peak intensity of X-ray diffraction in the central portion of the cross section parallel to the main surface in the longitudinal direction. The difference from the ratio {(006) plane / (110) plane} is 0.0005 to 0.15 in absolute value.

  Furthermore, the average void ratio is 4% or less, and the difference between the void ratio at the center of the main surface in the longitudinal direction and the void ratio at the end of the main surface in the longitudinal direction is 2% or less in absolute value, And the difference between the void ratio in the central part of the main surface and the void ratio in the central part of the cross section parallel to the main surface is 2% or less in absolute value.

  The method for producing the alumina sintered body is a step of preparing a slurry having a viscosity of 0.05 to 0.5 Pa · s prepared by mixing alumina powder, a solvent, a binder, a dispersant, and a crosslinking agent. A step of forming a water-repellent substance on the inner surface in the longitudinal direction of the non-water-absorbing mold, a step of filling the slurry while vibrating the mold at a frequency of 1 to 30 Hz and an amplitude of 0.2 to 5.0 mm; It is characterized by having.

  Furthermore, the alumina sintered body is used as a support member.

  According to the present invention, it is possible to obtain an alumina-based sintered body that is free from defects such as deformation, cracking, and breakage while maintaining high strength. When such an alumina sintered body is used as a structural member, the rigidity can be obtained without increasing the thickness beyond the required shape, and thus the weight can be reduced. Furthermore, when the mold is vibrated, a water-repellent substance is interposed on the inner surface, so that the occurrence of density differences due to crystal orientation in the longitudinal direction and thickness direction can be suppressed, making the mechanical strength of each part more uniform. An alumina sintered body having no difference can be obtained.

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

  The present invention is a substantially rectangular parallelepiped alumina sintered body having a length of 2000 mm or more, a width of 100 mm or more, and a thickness of 20 mm or more, and a peak intensity ratio {(006) plane of X-ray diffraction at the center of the main surface in the longitudinal direction. / (110) plane} and the X-ray diffraction peak intensity ratio {(006) plane / (110) plane} at the end of the main surface in the longitudinal direction are 0.01 to 0.15 in absolute value. It is characterized by being.

  FIG. 3 shows an example of an X-ray diffraction chart of the alumina sintered body of the present invention. The vertical axis in FIG. 3 indicates the peak intensity, and the horizontal axis indicates the diffraction angle. The crystal peak corresponding to the (006) plane exists between the diffraction angles 2θ = 41 ° to 42 ° in FIG. 3, and the crystal peak corresponding to the (110) plane is the diffraction angle 2θ = 37 ° in FIG. It exists between ˜38 °.

In the present invention, X-ray diffraction is performed on the central portion 1 and the end portion of the main surface in the longitudinal direction, or the central portion 3 of the cross section parallel to the main surface and the central portion 1 of the main surface, respectively. The difference is obtained using the peak intensity ratio calculated from the chart as shown in FIG.
Here, the reason for comparing the peak intensity ratios of the (006) plane and the (110) plane in the X-ray diffraction between the central portion 1 and the end portion of the main surface in the longitudinal direction as described above will be described below.

  As described above, the present invention uses the gel casting method, which is casting, and fills a non-water-absorbing mold with the slurry. Non-water-absorbing means a mold made of a material that does not absorb water (liquid). In the present invention, it is more preferable to use a metal mold having good thermal conductivity. As a material of a typical metal mold, aluminum, aluminum alloy, titanium, titanium alloy, magnesium alloy and the like are good because they are lightweight and have sufficient strength and heat resistance.

  After the slurry is filled, in the mold, various slurry flows occur due to the slurry filling method and the slurry colliding with the inner wall of the mold after the filling, but general alumina particles have a flat shape. In the direction in which the resistance decreases (the direction in which the thickness direction of the flat particles is perpendicular to the flow direction). In the alumina sintered body of the present invention, when the slurry is filled in a flow parallel to the longitudinal direction, various kinds of slurries are formed near the slurry filling port of the mold, near the end of the mold facing the mold, and further at the center. A flow is formed, and the alumina crystal particles have different crystal orientations.

  In the present invention, the distribution of the crystal orientation of the long plate-shaped product having different crystal orientations at the end portion 2 and the central portion 1 of the main surface is confirmed from the X-ray diffraction result on the product surface. It is.

  Then, from the diffraction chart, the ratio of the peak intensity of the (006) plane and the (110) plane of the alumina sintered body is calculated, and the difference in the ratio between the end portion 2 and the central portion 1 of the main surface in the longitudinal direction is calculated. Is within the predetermined range, there is no difference in shrinkage ratio that causes cracking or breakage in the alumina sintered body, and it is possible to produce a good substantially rectangular parallelepiped alumina sintered body. It is what I found.

  As described above, paying attention to the (006) plane and the (110) plane of the diffraction chart in X-ray diffraction, the ratio is calculated, and further, the difference between the central portion 1 and the end portion of the main surface in the longitudinal direction is confirmed with respect to this ratio. The reason for doing this is as follows.

  Here, the Miller index notation used for indicating the crystal orientation of the polycrystal is obtained by using the A, B, and C axes that intersect at right angles to each other in the directions of the crystals in the polycrystal. Of these, the axis along which the plane intersects is shown.

  Therefore, (006) represents a plane perpendicular to the C axis, and (110) represents that the crystal is oriented on a plane that intersects the A axis and the B axis and is parallel to the C axis. 110) planes intersect perpendicularly. Therefore, by confirming which of the two surfaces follows the crystal orientation, it can be confirmed whether the two have completely different crystal orientations.

  In general, the alumina sintered body produced by the press molding method or the like, the crystal orientation to the (110) plane and the other (104) plane, (113) plane, (116) plane appears remarkably, Usually, there is almost no peak on the (006) plane. Therefore, in the alumina sintered body having a particularly high peak intensity on the (006) plane, a large number of alumina crystal particles are oriented on a plane different from the conventional one.

  In such a case, when compared with the shrinkage behavior during firing of the alumina sintered body having general crystal orientation, particularly the shrink direction, the alumina sintered body having high crystal orientation toward the (006) plane is The shrinkage in a direction different from the shrinkage direction of a general alumina sintered body having a high crystal orientation toward the (110) plane is large. If the shrinkage difference in different directions becomes large in this way, strain stress is generated inside the sintered body, and if stress exceeding the strength of the sintered body is applied to the location where this stress is concentrated, The body will crack and break.

  Therefore, in a member in which the alumina particles are easily oriented in different directions in each part, it is possible to confirm the ratio of the peak intensity in the X-ray diffraction of the (006) plane and the (110) plane. It is important to obtain a union.

  In the present invention, the peak intensity ratio {(006) plane / (110) plane} in the X-ray diffraction of the (006) plane and (110) plane on the surface of the alumina sintered body is further confirmed. Difference between the {(006) plane / (110) plane} of the central portion 1 of the longitudinal main surface of the substantially rectangular parallelepiped shape with a length of 2000 mm or more and the {(006) plane / (110) plane} at the end, that is, the longitudinal direction It can be said that it is particularly important to confirm the variation of the crystal orientation in the range of 0.01 to 0.15 in order to obtain a product free from cracks and breakage.

  Here, as shown in FIG. 1, the central portion 1 of the main surface in the longitudinal direction is a straight line connecting points in the width direction that are ½ the length of the substantially rectangular parallelepiped alumina sintered body. Is a range having a width of ± 30 mm (1 in FIG. 1) toward both ends. Moreover, the edge part 2 of the main surface of a longitudinal direction means the range of the width (2 of FIG. 1) of 30 mm from the edge part of an alumina sintered compact.

  Further, when the difference between the central portion 1 and the end portion 2 of the principal surface of the peak intensity ratio (006) plane / (110) plane in the X-ray diffraction is less than 0.01, in the alumina sintered body The crystal particles are well dispersed in directions other than the C axis. In such a state, the alumina particles are flat, so that the contact area between the particles is small. If the contact area is small, it is difficult to increase the density of the alumina sintered body unless firing is performed at a higher temperature or the sintering property is not increased by adding a sintering aid component. Therefore, it is better to use a sintered body having a slight crystal grain orientation along the C axis from the viewpoint of increasing the density and increasing the strength. Further, when the difference between the central portion 1 and the end portion 2 of the principal surface of the peak intensity ratio (006) plane / (110) plane in X-ray diffraction exceeds 0.15, a large shrinkage difference is generated in the alumina sintered body. The substantially rectangular parallelepiped alumina sintered body is damaged and deformed from the center, and a good product cannot be obtained.

  Furthermore, in the present invention, the X-ray diffraction peak intensity ratio {(006) plane / (110) plane} at the central portion of the major surface in the longitudinal direction and the X at the central portion of the cross section parallel to the major surface in the longitudinal direction. The difference from the peak intensity ratio {(006) plane / (110) plane} of the line diffraction is preferably 0.0005 to 0.15 in absolute value.

  Here, when the range of 0.01 to 0.15 is X1, and the range of 0.0005 to 0.15 is X2, the range of X1 is the variation in the longitudinal direction, whereas the range of X2 is the meat. It can be said to be a means for confirming variation in the thickness direction. If the X2 is 0.0005 or more, as in the reason for the lower limit of the X1, since there is almost no orientation to the C axis, the alumina particles are flat, so the contact area between the particles is large. It becomes easy to densify the alumina sintered body. Therefore, in the production of an alumina sintered body in the gel casting method, it is possible to increase the density and the strength of the sintered body if the crystal orientation to the C axis is somewhat.

  Furthermore, if the value of X2 is 0.15 or less, the variation in the shrinkage difference of the sintered body in the thickness direction is small, and these act as stresses causing cracks and breakage on the sintered body. This is preferable because it does not occur.

  The central portion 3 of the cross section parallel to the main surface is, for example, the portion shown in FIG. 1, and the processing for performing X-ray diffraction of the central portion 3 of the cross section parallel to the main surface is a plane. The surface of the product may be shaved with a grinder or cut with a cutting machine such as a slicer. The surface roughness of the surface should be an arithmetic average surface roughness Ra of 500 μm or less.

  The alumina sintered body of the present invention has an average void ratio of 4% or less, and a void ratio at the center of the major surface in the longitudinal direction and a void ratio at the end of the major surface in the longitudinal direction. The difference between the absolute value is 2% or less, and the difference between the void ratio in the central portion of the main surface and the void ratio in the central portion of the cross section parallel to the main surface is 2% or less in absolute value. Is preferred.

  By setting the average void ratio of the alumina sintered body to 4% or less, it is possible to have mechanical characteristics equivalent to those of a conventional small-sized alumina sintered body.

  Further, by setting the void ratio difference between the central portion 1 of the main surface in the longitudinal direction and the end portion 2 of the main surface to 2% or less, the central portion 1 and the end of the main surface in the longitudinal direction of the large alumina sintered body The density difference generated in the portion 2 can be reduced, and the occurrence of variations in mechanical properties such as strength and Young's modulus due to the density difference can be suppressed.

  Furthermore, the variation in the mechanical characteristics in the thickness direction is suppressed by setting the void ratio difference between the central portion 1 of the main surface and the central portion 3 of the cross section parallel to the main surface to 2% or less. When such an alumina sintered body is used as a support member for a liquid crystal manufacturing apparatus, for example, deformation, cracking, or damage is caused by a load applied in the longitudinal direction and thickness direction. Good because there is no.

  If the average void ratio of the alumina sintered body is 4% or less, mechanical properties such as strength and Young's modulus are not deteriorated, and the central portion 1 of the main surface and the end portion 2 of the main surface, or the main When the void ratio difference between the central portion 1 of the surface and the central portion 3 of the cross section parallel to the main surface is 2% or less, the stress applied to the alumina sintered body on the portion with a high void ratio inferior to the mechanical properties This is not preferable because it concentrates and causes deformation, cracks and breakage.

As a method for measuring the void ratio, after the surface of the alumina sintered body is mirror-finished, an arbitrary 10 locations are observed with an image analyzer (LUZEX-FS manufactured by Nireco Corporation) at a magnification of 100 times. Then, the number of voids existing in the area 9 × 10 ⁴ μm ² and the average void diameter are measured, and then the total area is 9 × 10 ⁴ μm ² and the formula of total void number × void average diameter / total area × 100 is calculated. And calculated as a void fraction (%).

  The void ratio of the alumina sintered body of the present invention is obtained by measuring 10 points on the surface of the central portion 1 and the end portion 2 of the main surface shown in FIG. 1 and averaging them. is there.

  Regarding the void ratio difference, each of the central portion 1 and the end portion 2 of the main surface in the longitudinal direction, and the central portion 1 of the main surface and the central portion 3 of the cross section parallel to the main surface, respectively. The average of the measured values at any five points is calculated.

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

  As a method for producing an alumina sintered body of the present invention, a step of preparing a slurry having a viscosity of 0.05 to 0.5 Pa · s prepared by mixing alumina powder, a solvent, a binder, a dispersant, and a crosslinking agent, Forming a water-repellent substance on the inner surface in the longitudinal direction of the non-water-absorbing mold, filling the slurry while vibrating the mold at a frequency of 1 to 30 Hz and an amplitude of 0.2 to 5.0 mm. It is what you have.

  In the production method of the present invention, when the mold is vibrated, a water-repellent substance is interposed on the inner surface, thereby suppressing the occurrence of density differences due to the crystal orientation in the longitudinal direction and the thickness direction. It is possible to obtain an alumina sintered body having no difference in mechanical strength.

  Here, the viscosity of the slurry is set to 0.05 to 0.5 Pa · s as described above. When the viscosity is less than 0.05 Pa · s, the slurry is likely to leak from the mold, and the slurry viscosity should be kept low. Then, the powder content in the slurry must be reduced, and lowering the powder content is not preferable because the shrinkage after drying the slurry and the shrinkage during firing are increased.

  Furthermore, the value X1 of the difference in peak intensity ratio between the (006) plane and the (110) plane by X-ray diffraction of the central portion 1 of the main surface and the end portion 2 of the main surface is less than 0.01. This is not preferable. This is because, if this value is less than 0.01, the slurry viscosity is low and friction with the inner surface of the mold hardly occurs.

  Further, when the viscosity exceeds 0.5 Pa · s, when the slurry is filled into the mold, friction is generated between the inner wall of the mold and the slurry in contact with the inner wall, and the slurry is in contact with the inner wall by this frictional force. Crystal orientation is generated in the alumina particles on the surface, and the value of X1 exceeds 0.15, which is not preferable.

  In addition, the distance from the inner surface of the mold parallel to the slurry injection direction to the periphery of the slurry filling port is preferably within 150 mm. When the distance exceeds 150 mm, the distance between the slurry filling port and the inner wall of the molding die is increased, and the slurry is filled. When injected from the mouth, a portion where the fluidity of the slurry is remarkably deteriorated is generated at the end of the mold while reaching the surface of the inner wall from the filling port.

  Since the crystal orientation of the portion is different from the others, as a result, there is a high possibility that cracks and breakage will occur in each part of the molded body particularly near the filling port due to this shrinkage difference. A good alumina sintered body can be formed without the occurrence.

  The slurry is preferably degassed in a vacuum atmosphere of 0.01 MPa for 15 minutes to 2 hours before being injected into the mold. The slurry of the present invention has a relatively low viscosity, and there are few bubbles remaining in the slurry, but fine bubbles remain.If vacuum defoaming is performed, the slurry is injected into a mold and molded and fired. The void ratio in the alumina sintered body is 4% or less, the difference in the void ratio between the central portion 1 and the end portion 2 of the main surface in the longitudinal direction, and the cross section parallel to the central portion 1 of the main surface and the main surface It becomes easy to make the difference of the void ratio in the central part 3 of each 2% or less. It is considered that residual bubbles in the slurry are originally contained in the raw material powder and the binder, and most of them are considered to be removed by exposing the slurry for a certain period of time in a vacuum atmosphere in any of the slurry preparation steps. If the vacuum defoaming time is less than 15 minutes, bubbles remaining in the slurry cannot be sufficiently removed, and if the vacuum defoaming time exceeds 2 hours, the slurry is not preferable.

  FIG. 2A shows a schematic view when one end face in the longitudinal direction of the mold 10 provided with the slurry filling port 11 is viewed from the front. The slurry filling port 11 can be provided with various through-holes such as a circular shape and a polygonal shape in addition to the square as shown in the figure on the mold end surface 12. A slurry filling pump or the like (not shown) is connected to the slurry filling port 11, and the slurry 17 is filled into the molding die 10. And it is preferable that the distance from the shaping | molding die inner surface 13 shown by the dotted line of Fig.2 (a) is the slurry filling port 11 within 150 mm in both the width direction distance 14 and the height direction distance 15. FIG.

  Furthermore, before the slurry is filled, it is preferable that the slurry is filled with a water-repellent substance in the contact portion between the mold inner surface 13 and the slurry 17.

  FIG. 2B is a schematic diagram when the mold is viewed as a cross section perpendicular to the longitudinal direction. As shown in FIG. 2B, the mold 16 has a water repellent substance 18 interposed between the inner surface and the slurry 17 over the entire inner surface. By interposing the water repellent material 18, the water repellent effect of the solvent in the slurry 17 is exhibited, and the friction between the slurry 17 and the mold inner surface 13, which is one of the factors for orienting the alumina particles in the slurry 17. It can be reduced. For this reason, even in the sintered body after molding and firing, the orientation of the alumina crystal particles that cause cracks and breakage hardly occurs.

  As the water repellent material 18, a water repellent material such as a fluororesin, silicone, urea resin, melamine resin or the like is coated on the inner surface 13 of the mold, or is formed into a sheet and the entire inner surface 13 of the mold. Affix to and use.

  As shown in FIG. 2B, a vibration device 19 for applying vibration to the mold 16 is installed on the bottom surface side of the mold 16. Then, by filling the molding die 16 with the slurry 17 while vibrating the molding die 16, the vibration causes the alumina particles in the slurry 17, particularly the slurry 17 in contact with the molding die inner surface 13, or the slurry 17 near the molding die inner surface 13. It is possible to prevent the alumina particles therein from having orientation. In this method, the difference in the void ratio between the central portion 1 and the end portion of the main surface in the longitudinal direction, and the central portion of the cross section parallel to the central portion 1 and the main surface of the main surface, depending on the frequency and amplitude of vibration. 3 can be controlled. A larger vibration frequency of 1 to 30 Hz and an amplitude of 0.2 to 5 mm are more effective for preventing the alumina particles in the slurry 17 from having orientation. By performing molding while applying vibrations of this frequency and amplitude to the mold 16, the difference in peak intensity ratio between the central portion 1 of the main surface and the central portion 3 of the cross section parallel to the main surface is 0.0005. It is possible to produce a good alumina-based sintered body of the present invention having a range of ˜0.15 and free from cracks and breakage.

  As the vibration device, an electromagnetic vibration method is usually used, but various other commercially available vibration devices such as a piezoelectric type and an ultrasonic type can be adopted, and a structure for vibrating the mold 16 by resonance may be adopted. .

  As mentioned above, although embodiment of this invention was described, it cannot be overemphasized that it can apply also to what was variously improved and changed if it is the range which does not deviate from the scope of the present invention.

  Examples of the present invention will be described below.

Example 1
A member for a liquid crystal production apparatus of the present invention made of an alumina sintered body was produced by a gel casting method.

  First, a commercially available alumina raw material powder having a purity of 99% or more, a solvent (water), a binder, a dispersant, and a crosslinking agent were mixed using a universal mixing stirrer to prepare a molding slurry. As the molding slurry, the amount of solvent was adjusted, and after vacuum degassing for 30 minutes or more in a vacuum atmosphere of 0.01 MPa or less, molding slurries with various viscosities were prepared. In addition, about the slurry viscosity for shaping | molding, the value measured using the commercially available E-type viscosity meter is shown.

  Then, a metal mold capable of forming a long plate-shaped molded body having a width of 200 mm, a length of 2500 mm, and a thickness of 30 mm is prepared for the molding slurry, and a height of 20 mm and a width provided at the center of the end portion thereof. The molding slurry is filled from a 100 mm slurry filling port.

  Further, at the time of filling the molding slurry, the molding is performed while applying vibration with a frequency of 25 Hz and an amplitude of 3 mm to the molding die.

  Next, after filling the molding die with the molding slurry, the slurry filling port is closed so that the molding slurry does not flow out of the slurry filling port, and then the molding die is heated to gel the slurry. And the molded object which gelatinized is taken out from a shaping | molding die, it puts into a large sized dryer, it dries, and it is set as the molded object which evaporated the solvent.

  Thereafter, the compact was fired at a temperature of 1650 ° C. in a firing furnace to produce a substantially rectangular alumina sintered body.

  And as an evaluation method, X-ray diffraction of the end portion 2 of the main surface of the alumina sintered body and the central portion 1 of the main surface is performed, and from the diffraction chart, {(006) plane / (110) plane} peak intensity The difference in ratio was calculated. The manufactured alumina sintered body was immersed in the color check solution stored in the large water tank, and if there was a crack on the surface of the member, the color check solution soaked into the crack, and the appearance inspection was carried out so that the presence or absence of the crack could be confirmed. . Further, a part of the produced alumina sintered body was cut and processed into a test piece shape, and a three-point bending strength test based on JIS R1601-1995 was performed using this test piece. Moreover, the density measurement was implemented using the Archimedes method about the test piece after the said 3 point | piece bending test implementation.

These results are shown in Table 1.

  Sample No. which is outside the scope of the present invention. As for No. 1, although no cracks or breakage occurred in the sintered body in the appearance inspection, the sintered body was sintered at a firing temperature of 1650 ° C. due to the effect of reducing the amount of powder in the slurry as much as possible in order to reduce the slurry viscosity. The density was low and the strength was low. Further, the difference X1 in the peak intensity ratio between the central portion 1 of the main surface 1 and the end portion 2 of the {(006) plane / (110)} plane is as low as less than 0.01. , The strength is low.

  In addition, sample No. which is outside the scope of the present invention. For No. 7, the value of X1 was large, the shrinkage difference due to the crystal orientation of the alumina sintered body was large, and cracks were generated in the sintered body due to the stress generated thereby.

(Example 2)
Next, using the same steps as in Example 1, while applying vibrations having the frequencies shown in Table 2 to the mold, Sample No. which is the alumina sintered body of the present invention was used. The test which manufactures 8-14 was done. The test was conducted with the amplitude fixed at 3 mm.

  After the test, the produced alumina sintered body was processed to a thickness of ½ with a surface grinder, and X-ray diffraction analysis was performed on the center portion 3 of the processed surface to obtain {(006) Plane / (110) plane} was calculated, and the difference from the peak intensity ratio of {(006) plane / (110) plane} at the central portion 1 of the main surface was calculated.

The results are shown in Table 2.

  From Table 2, it was confirmed that the frequency of vibration applied to the mold should be 1 to 30 Hz in order to set X2 within the range of 0.0005 to 0.15.

  In addition, sample No. The member for a liquid crystal manufacturing apparatus of the present invention was manufactured in the same process as in Example 1 by fixing at the same frequency as 11 and changing the amplitude as shown in Table 3. After the member is manufactured, it is processed to a thickness of 1/2 with a surface grinder in the same manner as described above, and X-ray diffraction analysis is performed on the central portion 3 of the processed surface, and {(006) plane / The peak intensity ratio of (110) plane} was calculated, and the difference X2 between the peak intensity ratios of the (006) plane and the (110) plane at the center of the main surface obtained by performing X-ray diffraction analysis in advance was calculated.

The results are shown in Table 3.

  From Table 3, it was confirmed that the larger the amplitude of vibration given to the mold, the higher the density and strength of the alumina sintered body and the better the crystal orientation. This is because a water-repellent substance is formed on the inner surface, and if the water-repellent substance is not formed, the strength may decrease due to the difference in shrinkage due to orientation even if the density is improved by vibration applied to the mold. It can be said that there is.

(Example 3)
Using the same composition, the same shape, and the same manufacturing method as in Example 1, only the vacuum defoaming time of the slurry was variously changed to manufacture the liquid crystal manufacturing apparatus member of the present invention. Then, a test piece having a height of 3 mm, a width of 4 mm, and a length of 10 mm is cut out from the central portion 1 of the main surface, the end portion 2 of the main surface, and the central portion 3 of the cross section parallel to the main surface. After mirror finishing, 10 arbitrary positions were observed with an image analysis apparatus (LUZEX-FS manufactured by Nireco Corporation) at a magnification of 100 times. From this image, the number of voids present in an area of 9 × 10 ⁴ μm ² , void average After measuring the diameter, the 9 × 10 ⁴ μm ² is defined as the total area, and the void ratio (%) B1 (main surface center), B2 is calculated using the formula of total void number × void average diameter / total area × 100. (Main surface end) and B3 (central cross section parallel to the main surface) were calculated.

The results are shown in Table 4.

  From Table 4, sample No. 1 with a short vacuum defoaming time of less than 15 minutes and 10 minutes. For No. 22, the void ratio exceeds 4%, and the void ratio difference between the main surface center B1 and the main surface end B2 or the main surface center B1 and the central section B3 parallel to the main surface also exceeds 2%. When the three-point bending strength was measured based on the JIS standard, it showed a low value of 300 MPa or less, and the mechanical properties were not good.

  Sample No. Regarding 28, since the defoaming time was too long, the water was frozen and the slurry was solidified and could not be molded.

  In comparison with this, sample No. For Nos. 23 to 27, since good defoaming was carried out in 15 to 120 minutes, the void ratio showed a good value of 4% or less and a void ratio difference of 2% or less. All of these three-point bending test results were 300 MPa or more. It was confirmed that the material has excellent mechanical properties.

It is the schematic which shows the range of the main surface center, main surface edge part, and center cross section of the member for liquid crystal manufacturing apparatuses of this invention. It is explanatory drawing about the shaping | molding die of this invention, (a) is a schematic diagram of the longitudinal direction one side end surface of a shaping | molding die, (b) shows the cross section perpendicular | vertical to the longitudinal direction of a shaping | molding die, and the schematic diagram of a vibration apparatus cross section. It is an X-ray diffraction pattern of the alumina sintered body of one embodiment of the present invention.

Explanation of symbols

1: Central portion of main surface 2: End portion of main surface 3: Central portion of cross section parallel to main surface 10, 16: Mold 11: Slurry filling port 12: Mold end surface 13: Mold inner surface 14: (Mold Distance in the width direction 15 (of the filling port position relative to the inner surface of the mold): Distance in the height direction (of the filling port position relative to the inner surface of the mold) 17: Slurry 18: Water-repellent substance 19: Vibration device

Claims (5)

A substantially rectangular parallelepiped alumina sintered body having a length of 2000 mm or more, a width of 100 mm or more, and a thickness of 20 mm or more,
X-ray diffraction peak intensity ratio {(006) plane / (110) plane} at the center of the main surface in the longitudinal direction and X-ray diffraction peak intensity ratio {(006) plane at the end of the main surface in the longitudinal direction / (110) plane} is 0.01 to 0.15 in absolute value. X-ray diffraction peak intensity ratio {(006) plane / (110) plane} at the center of the principal surface in the longitudinal direction and X-ray diffraction peak intensity ratio at the center of the cross section parallel to the major surface in the longitudinal direction { 2. The alumina sintered body according to claim 1, wherein the difference between (006) plane / (110) plane} is 0.0005 to 0.15 in absolute value. The average void fraction is 4% or less,
The difference between the void ratio at the center of the main surface in the longitudinal direction and the void ratio at the end of the main surface in the longitudinal direction is 2% or less in absolute value, and the void ratio at the center of the main surface, The alumina sintered body according to claim 1 or 2, wherein a difference from a void ratio in a central portion of a cross section parallel to the main surface is 2% or less in absolute value. A method for producing an alumina sintered body according to any one of claims 1 to 3,
Preparing a slurry having a viscosity of 0.05 to 0.5 Pa · s prepared by mixing alumina powder, a solvent, a binder, a dispersant, and a crosslinking agent;
Forming a water-repellent substance on the inner surface in the longitudinal direction of the non-water-absorbing mold,
And a step of filling the slurry while vibrating the molding die at a frequency of 1 to 30 Hz and an amplitude of 0.2 to 5.0 mm. A liquid crystal manufacturing apparatus using the alumina sintered body according to claim 1 as a support member.

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