JP2018095504A - Manufacturing method of cylindrical ceramic sintered body and its cylindrical ceramic sintered body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a cylindrical ceramic sintered body with less deformation during manufacturing and having a stable shape even if repeatedly sintered, and the cylindrical ceramic sintered body.SOLUTION: A manufacturing method of a cylindrical ceramic sintered body which is sintered using a firing furnace has: a molding step S1 of filling a raw material powder into a cavity of a molding die, followed by compression molding so as to obtain the cylindrical ceramic molded body; an arranging step S2 of arranging the cylindrical ceramic molded body in the firing furnace; and a firing step S3 of obtaining the cylindrical ceramic sintered body by firing the arranged cylindrical ceramic molded body in the firing furnace. The arranging step S2 puts a plurality of supporting members side by side on the hearth in the firing furnace or on the bottom board placed on the hearth. The supporting members are stacked in three tiers or more per one place, and the cylindrical ceramic sintered body is mounted upright on the supporting members.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a cylindrical ceramic sintered body used as a sputtering target in a magnetron rotary cathode sputtering apparatus, and a cylindrical ceramic sintered body.

  Conventionally, a flat plate is generally used as a sputtering target, but when this flat plate target is used for sputtering by a magnetron sputtering method, the use efficiency is 10% to 30%. Stay at%. This is because in magnetron sputtering, plasma is concentrated and collides with a specific part of a flat target by a magnetic field, causing a phenomenon in which erosion proceeds to a specific part of the target surface, and the deepest part reaches the backing plate in the target. This is because the life of the target is reached.

  In response to this problem, it has been proposed to increase the usage efficiency of the target by making the sputtering target cylindrical. This sputtering method uses a cylindrical sputtering target consisting of a cylindrical backing tube and a cylindrical target material formed on the outer periphery thereof, and a magnetic field generating facility and a cooling facility are installed inside the backing tube, Sputtering is performed while rotating the sputtering target. By using such a cylindrical sputtering target, the usage efficiency of the target can be increased to 60% to 70%. In addition, since this sputtering method is excellent in cooling efficiency, it is possible to increase the input power and form a film at a high film formation rate.

  As a material for such a cylindrical sputtering target, a metal material that can be easily processed into a cylindrical shape and has high mechanical strength is widely used. However, ceramic materials have low mechanical strength and are brittle. It has not yet spread.

  Ceramic cylindrical sputtering targets are sprayed by spraying ceramic powder on the outer periphery of a cylindrical backing tube, or filled with ceramic powder on the outer periphery of a cylindrical backing tube. The ceramic powder is generally manufactured by hot isostatic pressing (HIP) method or the like. However, the thermal spraying method has a problem that it is difficult to obtain a high-density target. Further, the HIP method has a problem that initial cost and running cost are high, peeling due to a difference in thermal expansion, and further, recycling of the target and the backing tube cannot be performed.

  On the other hand, in recent years, a cylindrical ceramic molded body is formed by a cold isostatic press (CIP) method, placed on a floor plate in a firing furnace, and fired to obtain a cylindrical ceramic sintered body. After that, a manufacturing method of a cylindrical sputtering target in which a cylindrical target material is obtained by grinding and joined to a cylindrical backing tube has been studied. According to this method, a high-density cylindrical sputtering target can be easily obtained at a relatively low cost in industrial scale production. In addition, since the backing tube can be easily removed from the cylindrical target material and recycled after sputtering, the cost of the cylindrical sputtering target can be reduced.

  In this method, when the cylindrical ceramic compact shrinks in the firing step, the cylindrical ceramic sintered body obtained by the frictional force acting between the lower end surface (the surface in contact with the base plate during firing) and the base plate. There is a problem that the body is greatly deformed. The cylindrical ceramic sintered body thus deformed not only becomes difficult to attach to the processing equipment in the subsequent grinding process, but also increases the amount of grinding and significantly reduces the productivity. Further, fine cracks (microcracks) and chips are likely to occur during processing, which causes cracks and chips in the cylindrical target material during bonding (bonding) to the backing tube and sputtering.

  With respect to this problem, in Patent Document 1, a cylindrical ceramic molded body, which is an object to be fired, is placed on a floor plate made of a plate-shaped ceramic molded body having a sintering shrinkage rate equivalent to that of the cylindrical ceramic molded body. It describes a method of placing and spreading a powder such as alumina powder between a plate-like ceramic molded body and a cylindrical ceramic molded body.

  In Patent Document 2, a base body (laying plate) having a flat surface, a molded body support composed of a plurality of independently movable members, and a round bar or a spherical ceramics sintered body between the base body and the molded body support body And a method of firing using a firing jig provided with a sliding layer composed of:

  However, in these methods, the sliding layer composed of a round bar or a spherical ceramic material has low stability, and is generated by slight inclination of the hearth, decomposition of atmospheric gas or organic components supplied into the furnace. Due to the influence of the air flow, there is a problem that the cylindrical ceramic molded body moves in the furnace together with the sliding layer and comes into contact with the furnace wall and the adjacent cylindrical ceramic molded body. In addition, the arrangement of the cylindrical ceramic molded body in the firing furnace is set so that the cylindrical ceramic molded body is uniformly fired in consideration of the influence of the decomposition product gas and the atmospheric gas supplied to the furnace. However, there is a problem that the cylindrical ceramic molded body is not uniformly fired by such movement.

  On the other hand, in Patent Document 3, a plurality of support members are arranged on the base plate having the air holes so that the longitudinal direction thereof coincides with the radial direction of the circle around the air holes, There has been proposed a method in which a cylindrical molded body is placed vertically thereon. According to this method, movement of the cylindrical molded body in the horizontal direction in the furnace is suppressed, and the coefficient of friction between the oxides is small, so that the support member slides on the floor plate, so that deformation is small and a homogeneous sintered body is obtained. It is said.

JP 2005-281862 A JP 2008-184337 A Japanese Patent Laid-Open No. 2006-88831

  In the method of manufacturing a cylindrical ceramic sintered body, if the firing furnace is repeatedly used, the sliding function cannot be sufficiently exhibited due to deformation or fixing of the support or the support member, and the The cylindrical ceramic molded body may be greatly deformed by the catch. Further, depending on the shape of the support member, when the weight of the molded body increases, the support member bites into the molded body, and it may be necessary to provide a machining allowance for removing the amount.

  In view of the above situation, the present invention is a cylindrical ceramic sintered body used as a sputtering target in a magnetron type rotary cathode sputtering apparatus, and has a stable shape even when repeatedly fired with little deformation during sintering. An object of the present invention is to provide a method for producing a shaped ceramic sintered body and a cylindrical ceramic sintered body.

  In view of the above-mentioned problems, the present inventors have repeatedly studied earnestly about a method for suppressing deformation associated with sintering shrinkage of a cylindrical ceramic sintered body, and radially arranged support members having high-temperature durability, In the firing method using the slip of the surface, it was found that the slip of the surface can be used more stably even in the repeated test by forming the support member into a flat plate shape and stacking a plurality of the support members.

  That is, one aspect of the present invention is a method of manufacturing a cylindrical ceramic sintered body in which a cylindrical ceramic molded body is fired using a firing furnace, in which a raw material powder is filled in a cavity of a cylindrical forming mold and subjected to processing. A forming step of obtaining a cylindrical ceramic formed body by pressure forming, an arranging step of placing the cylindrical ceramic formed body in the firing furnace, and a cylinder obtained by firing the placed cylindrical ceramic formed body in the firing furnace A firing step of obtaining a ceramic sintered body, and in the placement step, a plurality of support members are arranged on a hearth in a firing furnace or a floor plate installed on the hearth, and the support members are arranged at one place. Three or more stages are stacked and placed, and the cylindrical ceramic molded body is placed upright on the support member.

  According to one aspect of the present invention, the cylindrical ceramic molded body can be stably supported while reducing the frictional force by utilizing the slip between a plurality of (three or more stages) support members, Deformation associated with sintering shrinkage can be stably suppressed.

  At this time, in one embodiment of the present invention, a flat plate can be used as the support member.

  By using a flat plate, the amount of depression due to the support member biting into the cylindrical ceramic molded body can be suppressed.

  At this time, in one embodiment of the present invention, the thickness of the support member can be set to 0.5 mm to 5 mm.

  It is preferable that the thickness of the support member is 0.5 mm or more and 5 mm or less in consideration of stacking and replacement at low cost.

  In one embodiment of the present invention, the support member may be made of a ceramic sintered body.

  A ceramic sintered body is suitable as a support member because it has high-temperature durability and its surface state does not easily change.

  In one embodiment of the present invention, the support member may be made of alumina or zirconia.

  Alumina or zirconia is preferred because it has high-temperature durability, its surface state does not easily change, and does not react with the cylindrical ceramic molded body during firing.

  In one embodiment of the present invention, the surface roughness of the support member may be 5 μm or less in terms of arithmetic average roughness Ra.

  In order to reduce the frictional force between the stacked support members, the surface roughness of the support member is preferably within the above range.

  In another aspect of the present invention, the difference between the maximum value and the minimum value of the inner diameter measured at four or more positions in the circumferential direction is 1.5 mm or less on the end surface on the ground surface side and the contact surface with the support member during firing It is a cylindrical ceramic sintered body having a dent of 0.3 mm or less.

  According to another aspect of the present invention, a cylindrical ceramic sintered body with excellent dimensional accuracy is obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the cylindrical ceramic sintered compact which can suppress the deformation | transformation at the time of sintering can be provided. The cylindrical ceramic sintered body obtained by such a manufacturing method not only has high dimensional accuracy and can reduce the amount of grinding, but also cracks when it is bonded to a backing tube to produce a cylindrical sputtering target. It is possible to effectively suppress the occurrence of defects and chipping. Therefore, according to the present invention, it is possible to provide a cylindrical sputtering target with a higher yield and lower cost than the conventional one, and its industrial significance is extremely high.

It is process drawing which shows the outline of the process in the manufacturing method of the cylindrical ceramic sintered compact concerning one Embodiment of this invention. It is a schematic sectional drawing for demonstrating arrangement | positioning of the cylindrical ceramic molded object in a baking furnace. It is a top view for demonstrating arrangement | positioning of the cylindrical ceramic molded object in a firing furnace. It is a schematic sectional drawing for demonstrating an effect | action of a support member at the time of a baking process when a cylindrical ceramic molded object shrink | contracts.

Hereinafter, a method for manufacturing a cylindrical ceramic sintered body and a cylindrical ceramic sintered body according to the present invention will be described in the following order with reference to the drawings. In addition, this invention is not limited to the following examples, In the range which does not deviate from the summary of this invention, it can change arbitrarily.
1. 1. Manufacturing method of cylindrical ceramic sintered body 1-1. Molding process 1-2. Arrangement process 1-3. Firing step Cylindrical ceramic sintered body

<1. Manufacturing method of cylindrical ceramic sintered body>
FIG. 1 is a process diagram showing an outline of a process in a method for producing a cylindrical ceramic sintered body according to an embodiment of the present invention. One embodiment of the present invention is a method for producing a cylindrical ceramic sintered body in which a cylindrical ceramic molded body is fired using a firing furnace, in which a raw material powder is filled in a cavity of a cylindrical forming mold and pressurized. A forming step S1 for forming a cylindrical ceramic formed body by molding, an arranging step S2 for disposing the cylindrical ceramic formed body in a firing furnace, and firing the cylindrical ceramic formed body in the firing furnace. A calcining step S3 for obtaining a bonded body, and in the arranging step S2, a plurality of supporting members are arranged on a hearth in the calcining furnace or a floor plate installed on the hearth, and the supporting members are arranged in three stages at one place. The stacked ceramic ceramics are placed in an upright state on the support member and placed in an upright state.

  By utilizing such slip between the plurality of support members, it is possible to stably support the cylindrical ceramic molded body while reducing the frictional force, and even during repeated tests, the support member can be deformed and fixed. Less susceptible to damage. This invention is completed based on the knowledge that the deformation | transformation accompanying sintering shrinkage can be suppressed stably by this.

  Hereinafter, each step will be described in detail. In addition, although the manufacturing method of the cylindrical ceramic sintered compact which concerns on one Embodiment of this invention is not restrict | limited by the size of the cylindrical ceramic sintered compact to manufacture, below, mainly an outer diameter is 80 mm- A case where a cylindrical ceramic sintered body having a diameter of 200 mm, an inner diameter of 40 mm to 190 mm, and a total length of 50 mm to 500 mm is manufactured will be described as an example.

(1-1. Molding process)
The forming step S1 is a step in which the raw material powder is filled in the cavity of the cylinder forming mold and is pressure-formed by, for example, the CIP method to obtain a cylindrical ceramic formed body.

[Raw material powder]
In the present invention, the raw material powder is not particularly limited, and can be appropriately selected according to the composition of the target cylindrical sputtering target. For example, when obtaining a cylindrical sputtering target made of ITO (Indium Tin Oxide), indium oxide (In ₂ O ₃ ) powder and tin oxide (SnO) powder can be used as the raw material powder. Further, in order to obtain a cylindrical sputtering target made of AZO (Aluminium Zinc Oxide) as the raw material powder, aluminum oxide _(Al 2 _{O 3)} can be used powder and zinc oxide (ZnO) powder.

  It is possible to mix the raw material powder at a predetermined ratio and then mold it as it is. However, after mixing with pure water, a binder, a dispersing agent, etc., spray-dried to form a granulated powder and then into the cavity It is preferable to fill. The granulated powder has higher fluidity than the raw material powder and is excellent in filling property. For this reason, by using the granulated powder instead of the raw material powder, a high-density cylindrical ceramic molded body can be easily obtained even in industrial scale production.

[Molding]
Molding is generally CIP (Cold Isostatic Pressing) molding, but is not limited to CIP molding as long as a high-density cylindrical formed body can be obtained. In the case of CIP molding, a raw material powder or granulated powder is filled in a cavity, and then a cylinder forming mold is put into a CIP apparatus and pressure-molded. In order to prevent a pressure medium such as water from entering the mold, the cylinder forming mold may be vacuum-packed and put into the CIP apparatus. The holding pressure in CIP molding is preferably 98 MPa to 294 MPa. When the holding pressure is less than 98 MPa, the density of the obtained cylindrical ceramic molded body may not be sufficiently high. On the other hand, when the holding pressure exceeds 294 MPa, the load on the CIP device is excessively increased and the production cost is increased.

  In addition, it is preferable to set it as 1 minute-30 minutes, and, as for the time (holding time) hold | maintained by holding pressure, it is more preferable to set it as 3 minutes-10 minutes. If the holding time is less than 1 minute, the density of the obtained cylindrical ceramic molded body may not be sufficiently high. On the other hand, if the holding time exceeds 30 minutes, productivity will deteriorate.

(1-2. Arrangement process)
The placement step S2 is a step of placing the cylindrical ceramic formed body obtained in the forming step S1 in a firing furnace using a support member.

[Arrangement]
FIG. 2 is a schematic cross-sectional view for explaining the arrangement of the cylindrical ceramic compact in the firing furnace, and FIG. 3 is a plan view for explaining the arrangement of the cylindrical ceramic compact in the firing furnace. . In the present invention, a plurality of support members 15 are arranged on the floor 11 installed on the hearth 11 or the hearth in the firing furnace, and the support members 15 are further stacked in three or more stages per place, The cylindrical ceramic molded body 16 is placed on the support member 15 in an upright state, and then fired. Further, when the vent hole 12 is provided in the hearth 11 or the like, a plurality of support members 15 are arranged on the radiation centering on the vent hole 12 of the hearth, and the support members 15 are stacked in three or more stages at one place. The cylindrical ceramic molded body 16 may be placed upright and fired on the support member 15 so that the center of the vent 12 of the hearth 11 coincides with the cylindrical axis. In addition, about the coincidence of the center of the vent hole 12 and the cylindrical axis, it is sufficient that they substantially coincide with each other. In the range where the effect of the present invention is sufficiently obtained, it is allowed.

  More specifically, first, a hearth 11 having a vent 12 is prepared. At this time, the vent 12 also serves as an atmosphere gas supply port. Next, the support members 15 are arranged radially around the vent hole 12. At this time, for example, as shown in FIG. 3, it is preferable to arrange the plurality of support members 15 at equal intervals in the circumferential direction. Then, it is preferable to stack three or more support members 15 (for example, support members 15A, 15B, and 15C in FIG. 2). The cylindrical ceramic molded body 16 is placed in an upright state and fired so that the center and the cylindrical axis coincide with each other. Depending on the size of the firing furnace, one or more cylindrical ceramic molded bodies 16 can be arranged. In this case, a plurality of vent holes 12 (atmosphere gas supply ports) are provided in the hearth 11, A support member is disposed around each vent. At this time, it is only necessary that the vent holes have an interval that does not allow the molded bodies to interfere with each other.

In addition, when baking the several types of molded object from which a shape differs, you may install the base plate 13 on the hearth 11. The floor plate 13 is required to have high-temperature durability, its surface state does not easily change, and does not react with the cylindrical ceramic formed body 16 during firing. For this reason, the material is appropriately selected depending on the firing temperature of the cylindrical ceramic molded body 16 and the like, and typical materials thereof are ceramic sintered bodies such as alumina (Al ₂ O ₃ ) and zirconia (ZrO ₂ ). Can be used. Further, the floor plate 13 is provided with a vent hole 14. The vent plate 14 is formed such that the upper surface of the floor plate 13 is located at a position where the molded body is disposed, and the lower surface of the floor plate is the position of the vent hole 12 of the hearth 11 so that atmospheric gas can be supplied through the vent hole 14 of the floor plate 13. Form. Thereby, the center position of the vent hole 14 and the center position of the cylindrical ceramic molded body 16 can be easily matched by using the floor plate 13 corresponding to the type of the molded body.

  FIG. 4 is a schematic cross-sectional view for explaining the operation of the support member when the cylindrical ceramic formed body contracts in the firing step. In such a method, compared with the frictional force acting between the cylindrical ceramic molded body 16 and the support member 15A or between the support member 15C and the floor plate 13 (or the hearth 11), the ceramic sintered bodies are connected to each other. Since the frictional force acting between certain support members (between 15A and 15B and between 15B and 15C) is extremely small, the support member 15 mounts the cylindrical ceramic compact 16 when the cylindrical ceramic compact 16 is sintered and contracted. It is possible to slide while being placed, and deformation due to sintering shrinkage can be greatly suppressed. In addition, since a plurality of sliding surfaces having a small frictional force are present by stacking a plurality of support members 15 (two locations in the case of three sheets), the sliding movement can be performed more smoothly. Furthermore, even if the sliding surface is caught due to surface roughness increase or fusion due to deterioration in repeated use or use at high temperature, another sliding surface slips and does not cause a great influence. The support member whose sliding has deteriorated may be replaced at the next use, and the possibility that all the sliding surfaces are fixed at once is extremely rare.

  In addition, when using the floor plate 13, as described in Patent Document 3, by using the same material as the support member 15, the frictional force can be reduced as described above. However, although it is necessary to keep the surface roughness fine in order to ensure slipping, the floor plate 13 is heated by placing a heavy article as a molded body, and therefore, if it is repeatedly used, scratches, dents, cracks, and chips are inevitably generated. In such a case, the floor board 13 needs to be replaced. However, the floor board 13 has a large area and needs to be provided with the vent hole 14, so that a high replacement frequency causes an increase in cost. In this case, as described above, by using a plurality of support members 15, the friction coefficient can be reduced between the support members 15A, 15B, and 15C, so that the surface state of the floor plate 13 is not affected. . Therefore, it is not necessary to strictly manage the surface state of the floor plate 13. Further, considering the cost, the material of the floor plate 13 may be changed to a material different from that of the support member 15, or the surface roughness may be roughened.

The vent hole 12 is required to have a size that can secure a sufficient supply amount of the atmospheric gas and that does not drop the support member that has been slid during firing. Therefore, it is preferable to adjust the range of the open area rate of the vent holes of ^{3cm 2 ~30cm} 2.

  Moreover, since the moving direction of the support member 15 is limited to the direction from the radially outer side of the cylindrical ceramic molded body 16 toward the center (the arrow direction in FIG. 4), it occurs during slight inclination of the hearth 11 or firing. It is possible to prevent the cylindrical ceramic molded body 16 from moving due to the influence of the air flow and coming into contact with the furnace wall or the adjacent cylindrical ceramic molded body.

[Support member]
The support member 15 is required to have high temperature durability, its surface state does not easily change, and does not react with the cylindrical ceramic formed body 16 during firing. For this reason, the material is appropriately selected depending on the firing temperature of the cylindrical ceramic molded body 16 and the like, and typical materials thereof are ceramic sintered bodies such as alumina (Al ₂ O ₃ ) and zirconia (ZrO ₂ ). Can be used.

  In the case of using a ceramic sintered body as the support member 15, it is preferable that the surface roughness of at least the contact surfaces among these surfaces is 5 μm or less in terms of arithmetic average roughness Ra, and 3 μm or less. More preferably, it is more preferably 2 μm or less. If the surface roughness of the support member 15 is in such a range, the static friction coefficient μ at these contact surfaces is about 0.1 to 1.5, preferably about 0.1 to 1.0, A smooth sliding movement of the support member 15 becomes possible during the firing process. On the other hand, when the surface roughness of these contact surfaces exceeds 5 μm, the support members 15A, 15B, and 15C cannot slide smoothly and are accompanied by sintering shrinkage of the cylindrical ceramic molded body 16. It becomes difficult to suppress deformation. The surface roughness Ra of the support member 15 can be measured with a surface roughness measuring device.

  The support member 15 is required to place the cylindrical ceramic molded body 16 thereon and support it stably. For this reason, the supporting member 15 needs to be arranged at three or more locations. 4 or more are more preferable, and 6 or more are more preferable. However, if there are too many places where the support member 15 is installed, it interferes with each other when the support member 15 slides, so it is preferable to keep the number of places below 10 or less.

  It is desirable that the support members 15 be stacked three or more. Functionally, there is no upper limit to the number of sheets that can be stacked, but if they are stacked too high, they become unstable against shaking, so it is appropriate to keep the height below 30 mm.

  The shape of the support member 15 is preferably a flat plate shape. The shape of the flat plate in the length-width direction is not so limited, but it is sufficient that the flat plate has a size that does not fall off due to slippage when it slides in the cylindrical diameter direction due to sintering shrinkage. Moreover, since it does not move in the circumferential direction of the cylinder, it only needs to have a width that can be overlapped. However, when the shape of the support member 15 is a round bar shape or a square bar shape as described in Patent Document 3, if the weight of the molded body is increased, the support member is strongly bitten into the molded body, and the sintered body remains in a depressed shape. May be. In that case, in the subsequent grinding process, it is necessary to provide a machining allowance for removing that amount. Therefore, by using a flat plate instead of a round bar shape or a square bar shape, the amount of depression due to the support member biting into the molded body can be suppressed to 0.3 mm or less. The shape of the flat support member may be a rectangular shape, but may be a circular shape or a polygonal shape as long as it satisfies the requirement of not slipping down during sintering shrinkage. Further, the supporting members to be stacked do not necessarily have the same shape.

  For example, in the case of a flat rectangular plate, it is preferable that the width is about 15 mm to 30 mm and the length is about 20 mm to 60 mm. If it is a disk-shaped board, about (phi) 20-60 mm is preferable. The amount of depression due to biting depends on the material and height of the cylinder, and the sintering temperature, but it is sufficient if the supporting member has a width of 15 mm or more for ceramics of about 500 mm in height, such as ITO or AZO as described above. is there. If the thickness is too thin, it is easy to break and it is desirable to make it 30 mm or less when three or more sheets are stacked, so 0.5 mm to 10 mm is preferable. In particular, in order for the support member 15 to be easily replaceable at a low cost, the flat support member 15 may be as thin as 0.5 mm to 5 mm.

(1-3. Firing step)
The firing step S3 is a step of firing the cylindrical ceramic formed body arranged as described above using a firing furnace to obtain a cylindrical ceramic sintered body.

[Baking conditions]
The firing conditions of the cylindrical ceramic molded body should be appropriately selected according to the composition and size thereof, the characteristics of the firing furnace, etc., and are not particularly limited. In general, firing can be performed under the following conditions. it can.

a) Debinding step In the firing step, first, the organic components contained in the cylindrical ceramic molded body are heated from room temperature to a specific temperature (debinding temperature) over a certain period of time (debinding time). Need to be removed.

  The binder removal temperature at this time is preferably 300 ° C. to 600 ° C., more preferably 400 ° C. to 500 ° C. The binder removal time is preferably 50 hours to 300 hours, more preferably 100 hours to 300 hours. With such a binder removal temperature and binder removal time, the organic components contained in the cylindrical ceramic molded body can be sufficiently removed.

During the binder removal step, it is necessary to supply the atmospheric gas at a rate of 100 L / min to 600 L / min, preferably 200 L / min to 400 L / min per 1 m ³ of the furnace volume. The atmosphere may be air, oxygen, or any mixed gas thereof.

b) Sintering Step After the binder removal step, the furnace temperature is raised to the firing temperature, and this temperature is held for a certain period of time to sinter the cylindrical ceramic molded body.

  The firing temperature varies depending on the composition of the cylindrical ceramic molded body. For example, when indium oxide is the main component, the firing temperature is preferably set to 1200 ° C. to 1600 ° C., to obtain a high-density cylindrical ceramic sintered body. Therefore, it is more preferable to set it as 1300 to 1600 degreeC. On the other hand, when zinc oxide is the main component, it is preferably 1000 ° C. to 1400 ° C., and more preferably 1250 ° C. to 1350 ° C. from the same viewpoint. The holding time at the firing temperature is preferably 5 hours to 40 hours, more preferably 10 hours to 30 hours.

The atmosphere in the sintering stage varies depending on the composition of the cylindrical ceramic formed body, but depending on the composition, air, oxygen, or a mixed gas thereof is preferably 100 L / min to 600 L / min per 1 m ^{3 of} furnace volume. Supplies 200 L / min to 400 L / min.

<2. Cylindrical Ceramic Sintered Body>
The cylindrical ceramic sintered body according to an embodiment of the present invention is obtained by firing uniformly while suppressing deformation of the cylindrical ceramic molded body. For example, it can be obtained by the manufacturing method described above. Such a cylindrical ceramic sintered body is characterized by excellent dimensional accuracy. More specifically, when a plurality of supporting members are used, the sintering shrinkage is freely contracted without being fixed at the time of sintering, so that the amount of deformation of the cylindrical shape is within 1.5 mm. Moreover, by making the shape of the support member in contact with the cylindrical ceramics into a flat plate, it is possible to suppress the biting of the support member due to the weight of the molded body at the time of firing, and the amount of depression due to the biting can be suppressed to 0.3 mm or less. Thus, the cylindrical ceramic sintered body according to one embodiment of the present invention is a sintered body with excellent dimensional accuracy.

  The amount of deformation is based on the following measurement. The cylindrical ceramic sintered body according to an embodiment of the present invention has a deformation amount defined by the difference between the maximum value dmax and the minimum value dmin of the inner diameter d measured at four or more positions in the circumferential direction of the end surface on the ground side. Δd (= dmax−dmin) is 1.5 mm or less. Here, the four positions in the circumferential direction determine the first inner diameter by a straight line passing through the center of the cylindrical ceramic sintered body, and sequentially determine the inner diameter on the straight line at the position where the phase is shifted by 45 °. What is necessary is just to measure, and when there are many measurement locations, the angle from which the phase shifts may be determined according to the number.

  The dent amount was defined as the maximum depth at the position where the support member was in contact with the surface where the support member was not in contact. In addition, when there are a plurality of positions where the support member is in contact, the average value is used as the amount of biting. Moreover, the measurement method is measured using a depth gauge.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to a following example at all.

  In the following examples and comparative examples, the characteristics of the obtained cylindrical ceramic sintered body were evaluated by the following evaluation items. As an evaluation method, one sintered batch was produced by 8 batches / batch x 5 times (total of 40 pieces), and the number of deformations of 1.5 mm or more was counted.

Example 1
[Granulated powder]
In Example 1, first, the zinc oxide powder and the aluminum oxide powder were weighed so that the ratio of the aluminum oxide powder was 2% by mass. Pure water, polyvinyl alcohol (PVA) as a binder, and a dispersant are added so that the concentration of these raw material powders is 60% by mass, and they are mixed and crushed by a bead mill (manufactured by Ashizawa Finetech Co., Ltd.). As a result, a slurry was formed.

Next, this granulated powder was obtained by spray-drying this slurry with a spray dryer (made by Okawahara Kako Co., Ltd., ODL-20 type). When the tap density of this granulated powder was measured using a shaking specific gravity measuring device (KRS-409, manufactured by Kuramochi Scientific Instruments), it was confirmed to be 1.5 g / cm ³ .

[Molding process]
After filling this granulated powder into a cylindrical rubber mold, it is put into a cold isostatic press, and is molded by pressing with a holding pressure of 294 MPa and a holding time of 10 minutes, so that the outer diameter is 180 mm and the inner diameter is 150 mm. Eight cylindrical ceramic compacts having a total length of 350 mm were produced.

[Baking process]
A normal pressure firing furnace having eight cylindrical ceramic compacts obtained in the molding step and having an inner diameter of 40 mm (opening area: 12.6 cm ² ) and eight atmosphere gas supply ports and a furnace volume of 0.5 m ³ It was placed in (Marusho Denki Co., Ltd.) and baked.

First, for each cylindrical ceramic molded body, an alumina flooring plate having an inner diameter of 30 mm (opening area: 7.1 cm ² ) and having a ventilation hole of 250 mm length, 250 mm width, and 5 mm thickness is prepared. Were installed on the hearth. Next, around the vent hole, as a supporting member, a plate made of alumina having a width of 15 mm, a total length of 50 mm, and a height of 1 mm is arranged in three steps, a total of 24 pieces in eight locations, with the longitudinal direction centered on the vent hole, It was arranged radially so as to coincide with the radial direction of the circle centered on the vent hole. At this time, the flat plates were arranged at regular intervals in the circumferential direction. Subsequently, the cylindrical ceramic molded body was placed in an upright state on the support member so that the cylinder axis coincided with the center of the vent hole. In this example, as the support member, a surface roughness measured by a surface roughness measuring apparatus (manufactured by Mitutoyo Corporation, Surf Test SJ-210) having a surface roughness of 3 μm in arithmetic average roughness Ra was used.

In this state, the temperature is raised to 450 ° C. (debinder temperature) over 160 hours while circulating air at 300 L / min per 1 m ^{3 of} the furnace volume through the atmospheric gas supply port. The binder was removed by Then, while circulating oxygen at a volume of 300 L / min per 1 m ³ in the furnace, the temperature was raised to 1350 ° C., held at this temperature (firing temperature) for 20 hours, and the cylindrical ceramic compact was sintered, Eight cylindrical ceramic sintered bodies were produced. These cylindrical ceramic sintered bodies were taken out from the furnace, and the amount of deformation was measured.

  The above procedure was repeated 5 times to produce a total of 40 cylindrical ceramic sintered bodies. The number of deformation amounts of 1.5 mm or more at this time was counted.

(Example 2)
In Example 2, the raw material powder was a mixed powder of indium oxide powder and tin oxide powder, the ratio of the tin oxide powder was 10% by mass, and the concentration of the raw material powder was 65% by mass to form a slurry. . A spherical granulated powder was obtained in the same manner as in Example 1 except that the cylindrical ceramic molded body had an outer diameter of 200 mm, an inner diameter of 160 mm, and a total length of 330 mm. The tap density of this granulated powder was 1.5 g / cm ³ . The cylindrical ceramic compacts were respectively installed on a hearth having a vent hole with an inner diameter of 30 mm (opening area: 7.1 cm ² ) via a support member. In addition, 40 cylindrical ceramic sintered bodies were produced in the same manner as in Example 1 except that the binder removal temperature was 500 ° C. and the firing temperature was 1550 ° C. The results are shown in Table 1.

(Example 3)
In Example 3, the number of steps of the support member was five. Other than that, 40 cylindrical ceramic sintered bodies were produced in the same manner as in Example 1.

Example 4
In Example 4, the support member was made of zirconia. Other than that, 40 cylindrical ceramic sintered bodies were produced in the same manner as in Example 1.

(Example 5)
In Example 5, the support member having a surface roughness of 5 μm in arithmetic average roughness Ra was used. Other than that, 40 cylindrical ceramic sintered bodies were produced in the same manner as in Example 1.

(Example 6)
In Example 6, the support member was made of zirconia, and the surface roughness was 5 μm in arithmetic average roughness Ra. Other than that, 40 cylindrical ceramic sintered bodies were produced in the same manner as in Example 1.

(Example 7)
In Example 7, the support member was made of zirconia, and the width of the support member was 10 mm. Other than that, 40 cylindrical ceramic sintered bodies were produced in the same manner as in Example 1.

(Comparative Example 1)
In Comparative Example 1, the number of steps of the support member was two. Other than that, 40 cylindrical ceramic sintered bodies were produced in the same manner as in Example 1.

(Comparative Example 2)
In Comparative Example 2, the number of steps of the support member was one. Other than that, 40 cylindrical ceramic sintered bodies were produced in the same manner as in Example 1.

(Comparative Example 3)
In Comparative Example 3, a support member having a surface roughness of 6 μm in arithmetic average roughness Ra was used. Other than that, 40 cylindrical ceramic sintered bodies were produced in the same manner as in Example 1.

(Comparative Example 4)
In Comparative Example 4, the support member was made of zirconia, and the number of steps of the support member was two. Other than that, 40 cylindrical ceramic sintered bodies were produced in the same manner as in Example 1.

(Comparative Example 5)
In Comparative Example 5, the support member was made of zirconia, and the surface roughness was 6 μm in arithmetic mean roughness Ra. Other than that, 40 cylindrical ceramic sintered bodies were produced in the same manner as in Example 1.

(Comparative Example 6)
In Comparative Example 6, a cylindrical support member (one stage) having a width of 3 mm and a total length of 50 mm was used. Other than that, 40 cylindrical ceramic sintered bodies were produced in the same manner as in Example 1.

(Comparative Example 7)
In Comparative Example 7, a prismatic support member (one stage) having a width of 3 mm and a total length of 50 mm was used. Other than that, 40 cylindrical ceramic sintered bodies were produced in the same manner as in Example 1.

  In Comparative Examples 6 and 7, the surface of the floor plate that comes into contact with the support member had a surface roughness equivalent to that of the support member. Moreover, when performing repeatedly, the supporting member was installed in the state as it is.

  About the said Example and the comparative example, the deformation amount of 40 cylindrical ceramic sintered compacts was measured, respectively, and the number of the deformation amount of 1.5 mm or more at that time was counted. Moreover, the amount of depressions was measured. The results are shown in Table 1.

  From Table 1, it can be seen that in the examples, the number of deformation exceeding 1.5 mm is 0, the shape of the sintered body is good, and the dimensional accuracy is maintained even after repeated 5 times. In the comparative example, as in comparative example 2, it can be seen that the amount of deformation is large when the number of supporting members is one, the frictional resistance is large, and no slip occurs. If the surface roughness of the support member exceeds Ra 5 μm, the frictional resistance increases, and a sintered body having a deformation amount exceeding 1.5 mm is generated in part. In addition, since the hollow amount of the sintered compact used the flat support member, the hollow did not generate | occur | produce 0.3 mm or more.

DESCRIPTION OF SYMBOLS 11 Hearth, 12 (furnace floor) vent, 13 laying board, 14 (laying board) vent, 15 (15A, 15B, 15C) Support member, 16 Cylindrical ceramic molded object

Claims (7)

A method for producing a cylindrical ceramic sintered body by firing a cylindrical ceramic molded body using a firing furnace,
A forming step of filling a raw material powder into a cavity of a cylindrical forming mold and press-molding to obtain a cylindrical ceramic molded body,
An arranging step of arranging the cylindrical ceramic molded body in the firing furnace;
A firing step of firing the arranged cylindrical ceramic compact in the firing furnace to obtain a cylindrical ceramic sintered body;
In the arrangement step, a plurality of support members are arranged on a hearth in the firing furnace or a floor plate installed on the hearth, and the support members are stacked in three or more stages at one place. A method for producing a cylindrical ceramic sintered body, wherein the cylindrical ceramic molded body is placed in an upright state.   The method for manufacturing a cylindrical ceramic sintered body according to claim 1, wherein a flat plate is used as the support member.   The method for manufacturing a sintered body according to claim 2, wherein the support member has a thickness of 0.5 mm or more and 5 mm or less.   The method for manufacturing a cylindrical ceramic sintered body according to any one of claims 1 to 3, wherein the support member is made of a ceramic sintered body.   The method for producing a cylindrical ceramic sintered body according to any one of claims 1 to 3, wherein the support member is made of alumina or zirconia.   The method for producing a cylindrical ceramic sintered body according to claim 4 or 5, wherein the surface roughness of the support member is 5 μm or less in terms of arithmetic average roughness Ra.   The difference between the maximum value and the minimum value of the inner diameter measured at four or more positions in the circumferential direction on the end surface on the ground surface side is 1.5 mm or less, and the depression on the contact surface with the support member during firing is 0.3 mm or less. Cylindrical ceramic sintered body.

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