JP6842293B2 - Manufacturing method of cylindrical ceramic sintered body - Google Patents

Description

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

Conventionally, a flat plate-shaped target is generally used as the sputtering target, but when sputtering is performed by the magnetron sputtering method using this flat plate-shaped target, the usage efficiency is 10% to 30%. Stay in%. This is because in the magnetron sputtering method, the plasma is concentrated and collided with a specific part of the flat target by the magnetic field, so that a phenomenon that erosion progresses to a specific part of the target surface occurs, and the deepest part reaches the backing plate in the target. This is because the life of the target will be reached when it is reached.

To solve this problem, it has been proposed to improve the utilization efficiency of the target by making the sputtering target cylindrical. This sputtering method uses a cylindrical sputtering target composed of a cylindrical backing tube and a cylindrical target material formed on the outer periphery thereof, and a magnetic field generation facility and a cooling facility are installed inside the backing tube to form a cylinder. Shape Sputtering is performed while rotating the target. By using such a cylindrical sputtering target, the utilization 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 forming speed.

As a material for such a cylindrical sputtering target, a metal material that is easy to process into a cylindrical shape and has high mechanical strength is widely used, but a ceramic material has low mechanical strength and is brittle. , Has not yet become widespread.

Ceramic cylindrical sputtering targets can be used by thermal spraying, in which ceramic powder is sprayed onto the outer circumference of a cylindrical backing tube, or by filling the outer circumference of a cylindrical backing tube with ceramic powder in an inert atmosphere at high temperature and high pressure. It is generally manufactured by a hot hydrostatic press (HIP) method or the like, in which the ceramic powder is fired in the above. However, the thermal spraying method has a problem that it is difficult to obtain a high-density target. Further, the HIP method has problems that the initial cost and the running cost are high, peeling due to the difference in thermal expansion, and the target and the backing tube cannot be recycled.

On the other hand, in recent years, a cylindrical ceramic compact is formed by a cold hydrostatic press (CIP) method, placed on a floor plate in a firing furnace, and fired to obtain a cylindrical ceramic sintered body. After that, a method for manufacturing a cylindrical sputtering target, in which a cylindrical target material is obtained by grinding and is joined to a cylindrical backing tube, is being studied. According to this method, a high-density cylindrical sputtering target can be easily obtained at a relatively low cost in industrial-scale manufacturing. Further, 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, in the firing step, when the cylindrical ceramic molded body shrinks, the cylindrical ceramics sintered obtained by the frictional force acting between the lower end surface (the surface in contact with the floor plate during firing) and the floor plate. There is a problem that the body is greatly deformed. The cylindrical ceramic sintered body deformed in this way not only becomes difficult to attach to the processing equipment in the subsequent grinding process, but also increases the grinding amount and significantly reduces the productivity. In addition, fine cracks (microcracks) and chips are likely to occur during processing, which causes cracks and chips of the cylindrical target material during bonding with the backing tube and during sputtering.

In response to this problem, in Patent Document 1, a cylindrical ceramic molded body 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. A method of placing and laying a spreading powder such as alumina powder between a plate-shaped ceramic molded body and a cylindrical ceramic molded body is described.

In Patent Document 2, a base (bed plate) having a flat surface, a molded body support composed of a plurality of independently movable members, and a round bar or a spherical seramics sintered body between the base and the molded body support. We are proposing 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 is not stable and is caused by a slight inclination of the hearth and decomposition of the atmospheric gas or organic component 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. Further, 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 due to such movement.

On the other hand, in Patent Document 3, a plurality of support members are arranged radially on a floor plate having ventilation holes so that the longitudinal direction coincides with the radial direction of the circle with the ventilation holes as the center. A method of vertically placing the cylindrical molded body on the cylindrical molded body has been proposed. According to this method, the movement of the cylindrical molded body in the furnace in the horizontal direction is suppressed, and since the friction coefficient between oxides is small, the support member slides on the floor plate, so that the deformation is small and a homogeneous sintered body can be obtained. It is supposed to be.

Japanese Unexamined Patent Publication No. 2005-281862 Japanese Unexamined Patent Publication No. 2008-184337 Japanese Unexamined Patent Publication No. 2016-88831

When the firing furnace is repeatedly used in the method for manufacturing a cylindrical ceramic sintered body, the sliding function cannot be sufficiently exhibited due to deformation or sticking of the support and the support member, and the support and the support member cannot be fully exhibited. The cylindrical ceramic molded body may be significantly deformed due to catching. Further, depending on the shape of the support member, when the weight of the molded body becomes heavier, the support member bites into the molded body more strongly, and it may be necessary to provide a processing allowance for removing the portion.

In view of the above situation, in view of the above situation, in a magnetron type rotary cathode sputtering apparatus, a cylindrical ceramic sintered body used as a sputtering target has little deformation at the time of sintering and has a stable shape even after repeated firing. It is an object of the present invention to provide a method for producing a shaped ceramics sintered body and a cylindrical ceramics sintered body.

In view of the above-mentioned problems, the present inventors have made extensive studies on a method for suppressing deformation of a cylindrical ceramic sintered body due to sintering shrinkage, and arranged support members having high temperature durability in a radial pattern. In the firing method utilizing the surface slip, it was found that the surface slip 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 for producing a cylindrical ceramics sintered body in which a cylindrical ceramics molded body is fired using a firing furnace, in which a raw material powder is filled in a cylindrically formed type cavity and added. A molding step of pressing to obtain a cylindrical ceramics molded body, an arrangement step of arranging the cylindrical ceramics molded body in the firing furnace, and firing the arranged cylindrical ceramics molded body in the firing furnace to form a cylinder. It has a firing step of obtaining a shaped ceramic sintered body, and in the arranging step, ceramics having a surface roughness of 5 μm or less in arithmetic average roughness Ra on the hearth in the firing furnace or a floor plate installed on the hearth. A plurality of support members made of a sintered body are arranged side by side, and the support members are placed on top of each other in three or more stages so that two layers of contact surfaces having a static friction coefficient μ of 0.1 to 1.0 are provided. Having the above, the cylindrical ceramics molded body is placed upright on the support member , and the obtained cylindrical ceramics sintered body is located at four or more positions in the circumferential direction on the end surface on the ground plane side. The difference between the maximum value and the minimum value of the inner diameter measured in 1 is 1.5 mm or less, and the recess of the contact surface with the support member during firing is 0.3 mm or less .

According to one aspect of the present invention, by utilizing the sliding between a plurality of (three or more steps) support members, it is possible to stably support the cylindrical ceramic molded body while reducing the frictional force. Deformation due to sintering shrinkage can be stably suppressed. The ceramic sintered body is suitable as a support member because it has high temperature durability and its surface condition does not change easily. Further, in order to reduce the frictional force between the stacked support members, it is preferable that the surface roughness of the support members is within the above range. As a result, a cylindrical ceramic sintered body having excellent dimensional accuracy is obtained.

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

By using a flat plate, it is possible to suppress the amount of dents caused by the support member being bitten into the cylindrical ceramic molded body.

At this time, in one aspect of the present invention, the thickness of the support member can be 0.5 mm or more and 5 mm or less.

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

Further, in one aspect of the present invention, the support member may be made of alumina or zirconia.

Alumina or zirconia is preferable because it has high temperature durability, its surface state does not change easily, and it does not react with a cylindrical ceramic molded product during firing.

According to the present invention, it is possible to provide a method for producing a cylindrical ceramic sintered body capable of suppressing deformation during sintering. 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 joined to a backing tube to prepare a cylindrical sputtering target. It is possible to effectively suppress the occurrence of chips and chips. Therefore, the present invention makes it possible to provide a cylindrical sputtering target in a higher yield and at a lower cost than before, and its industrial significance is extremely high.

It is a process drawing which shows the outline of the process in the manufacturing method of the cylindrical ceramic sintered body which concerns on one Embodiment of this invention. It is schematic cross-sectional view for demonstrating arrangement of a cylindrical ceramic compact in a firing furnace. It is a top view for demonstrating the arrangement of a cylindrical ceramic molded body in a firing furnace. It is schematic cross-sectional view for demonstrating the action of the support member at the time of shrinking a cylindrical ceramic compact in a firing step.

Hereinafter, the method for producing the cylindrical ceramic sintered body and the cylindrical ceramic sintered body according to the present invention will be described in the following order with reference to the drawings. The present invention is not limited to the following examples, and can be arbitrarily modified without departing from the gist of the present invention.
1. 1. Manufacturing method of cylindrical ceramic sintered body 1-1. Molding process 1-2. Placement process 1-3. Baking process 2. 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 manufacturing 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 cylindrical ceramic molded body and pressurized. A molding step S1 for obtaining a cylindrical ceramic molded body by molding, an arrangement step S2 for arranging the cylindrical ceramic molded body in a firing furnace, and firing the arranged cylindrical ceramic molded body in a firing furnace for firing the cylindrical ceramics. It has a firing step S3 for obtaining a body, and in the arrangement step S2, 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 arranged in three stages per place. The above-mentioned stacks are placed on top of each other, and the cylindrical ceramic molded body is placed upright on the support member.

By utilizing such sliding between a plurality of support members, it is possible to stably support the cylindrical ceramic molded body while reducing the frictional force, and the support members are deformed and fixed even in repeated tests. Less susceptible to damage. The present invention has been completed based on the finding that the deformation due to the sintering shrinkage can be stably suppressed by this.

Hereinafter, each step will be described in detail. The method for manufacturing the cylindrical ceramics sintered body according to the embodiment of the present invention is not limited by the size of the cylindrical ceramics sintered body to be manufactured, but in the following, the outer diameter is mainly 80 mm or more. A case of manufacturing a cylindrical ceramic sintered body having 200 mm, an inner diameter of 40 mm to 190 mm, and a total length of 50 mm to 500 mm will be described as an example.

(1-1. Molding process)
The molding step S1 is a step of filling the cavity of the cylindrically formed mold with the raw material powder and, for example, pressure molding by the CIP method to obtain a cylindrical ceramic molded product.

[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 trying to obtain 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 raw material powders. Further, when a cylindrical sputtering target made of AZO (Aluminium Zinc Oxide) is to be obtained, aluminum oxide (Al ₂ O ₃ ) powder and zinc oxide (Zn O) powder can be used as raw material powders.

It is also possible to mix the raw material powder in a predetermined ratio and then mold it as it is, but after mixing it with pure water, a binder, a dispersant, etc., it is spray-dried to form a granulated powder and then inside the cavity. It is preferable to fill the mixture. The granulated powder has higher fluidity than the raw material powder and is excellent in filling property. Therefore, by using the granulated powder instead of the raw material powder, a high-density cylindrical ceramic molded product 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 molded body can be obtained. In the case of CIP molding, after filling the cavity with the raw material powder or the granulated powder, the cylindrically formed mold is put into the CIP apparatus and pressure molded. In order to prevent a pressure medium such as water from entering the mold, the cylindrical mold may be vacuum-packed and then charged into the CIP device. The holding pressure in CIP molding is preferably 98 MPa to 294 MPa. If the holding pressure is less than 98 MPa, the density of the obtained cylindrical ceramic molded product may not be sufficiently high. On the other hand, if the holding pressure exceeds 294 MPa, not only the load on the CIP device becomes excessively large, but also the production cost increases.

The holding time (holding time) is preferably 1 minute to 30 minutes, and more preferably 3 minutes to 10 minutes. If the holding time is less than 1 minute, the density of the obtained cylindrical ceramic molded product may not be sufficiently high. On the other hand, if the holding time exceeds 30 minutes, the productivity will deteriorate.

(1-2. Placement process)
The arranging step S2 is a step of arranging the cylindrical ceramic molded body obtained in the molding step S1 in the firing furnace using a support member.

[Arrangement]
FIG. 2 is a schematic cross-sectional view for explaining the arrangement of the cylindrical ceramic molded body in the firing furnace, and FIG. 3 is a plan view for explaining the arrangement of the cylindrical ceramic molded body in the firing furnace. .. In the present invention, a plurality of support members 15 are arranged on a hearth 11 in a firing furnace or a floor plate 13 installed on the hearth, and the support members 15 are placed on top of each other in three or more stages. The cylindrical ceramic molded body 16 is placed upright on the support member 15, and then fired. When the vent 12 is provided in the hearth 11 or the like, a plurality of support members 15 are arranged radially around the vent 12 of the hearth, and the support members 15 are stacked in three or more stages at one location. The cylindrical ceramic molded body 16 may be placed upright on the support member 15 so that the center of the vent 12 of the hearth 11 and the cylindrical axis coincide with each other, and then fired. Regarding the coincidence between the center of the vent 12 and the cylindrical axis, it is sufficient that they substantially coincide with each other, and the deviation (for example, about 10% to 30% with respect to the inner diameter of the cylindrical ceramic molded body) is sufficient. , It is permissible as long as the effect of the present invention can be sufficiently obtained.

More specifically, first, a hearth 11 having a vent 12 is prepared. At this time, the vent 12 also serves as an atmospheric gas supply port. Next, the support member 15 is arranged radially around the vent 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 of the support members 15 (for example, the support members 15A, 15B, 15C in FIG. 2). The cylindrical ceramic molded body 16 is placed upright on it and fired so that the center and the cylindrical axis coincide with each other. It is possible to arrange one or more cylindrical ceramic molded bodies 16 according to the size of the firing furnace. In this case, a plurality of vents 12 (atmosphere gas supply ports) are provided in the hearth 11. The support member is arranged around each vent. At this time, the vents need only be spaced so that the molded bodies do not interfere with each other.

When firing a plurality of types of compacts having different shapes, the floor plate 13 may be installed on the hearth 11. It is necessary that the floor plate 13 has high temperature durability, its surface state does not change easily, and it does not react with the cylindrical ceramic molded body 16 at the time of firing. Therefore, the material is appropriately selected depending on the firing temperature of the cylindrical ceramic molded body 16, and the typical material thereof is a ceramic sintered body such as _{alumina (Al 2} O ₃ ) or zirconia (ZrO _2). Can be used. Further, the floor plate 13 is provided with a vent 14. The upper surface of the floor plate 13 is formed at a position where the molded body is arranged, and the lower surface of the floor plate 13 is a position of the vent 12 of the hearth 11 so that atmospheric gas can be supplied through the vent 14 of the floor plate 13. Form. Thereby, depending on the type of the molded body, the center position of the vent 14 and the center position of the cylindrical ceramic molded body 16 can be easily aligned by using the corresponding floor plate 13.

FIG. 4 is a schematic cross-sectional view for explaining the action of the support member when the cylindrical ceramic molded body shrinks in the firing step. In such a method, the ceramic sintered bodies have a frictional force acting between the cylindrical ceramic molded body 16 and the support member 15A and between the support member 15C and the floor plate 13 (or the hearth 11). 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 molded body 16 during the sintering shrinkage of the cylindrical ceramic molded body 16. It is possible to slide and move while it is placed, and deformation due to sintering shrinkage can be significantly suppressed. Further, by stacking a plurality of the support members 15, a plurality of sliding surfaces having a small frictional force exist (two locations in the case of stacking three members), so that the sliding movement can be performed more smoothly. Further, even if the sliding surface is caught by the increase in surface roughness due to deterioration or fusion due to repeated use or use at a high temperature, another sliding surface slips and does not cause a great influence. The support member with poor slippage may be replaced at the next use, and it is extremely rare that all the slippery surfaces are fixed at once.

Further, when the floor plate 13 is used, as described in Patent Document 3, by using the same material as the support member 15, the frictional force can be reduced in the same manner as described above. However, although it is necessary to keep the surface roughness of the floor plate 13 fine in order to secure slippage, since a heavy object such as a molded body is placed on it and heat is applied, scratches, dents, cracks, and chips are inevitably generated when it is used repeatedly. In such a case, it is necessary to replace the floor plate 13, but since the floor plate 13 has a large area and also needs to be processed to provide a vent 14, 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 condition of the floor plate 13 is not affected. .. Therefore, it is not necessary to strictly control the surface condition of the floor plate 13. Further, in consideration of 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 12 needs to be large enough to secure a sufficient supply amount of atmospheric gas and to prevent the support member that has slipped and moved during firing from falling. 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 radial outside of the cylindrical ceramic molded body 16 toward the center (the direction of the arrow in FIG. 4), it occurs when the hearth 11 is slightly tilted or fired. 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]
It is necessary that the support member 15 has high temperature durability, its surface state does not change easily, and it does not react with the cylindrical ceramic molded body 16 at the time of firing. Therefore, the material is appropriately selected depending on the firing temperature of the cylindrical ceramic molded body 16, and the typical material thereof is a ceramic sintered body such as _{alumina (Al 2} O ₃ ) or zirconia (ZrO _2). Can be used.

When a ceramic sintered body is used as the support member 15, the surface roughness of at least the contact surfaces of these surfaces is preferably 5 μm or less in arithmetic average roughness Ra, and is 3 μm or less. It is more preferable that the thickness is 2 μm or less. If the surface roughness of the support member 15 is within such a range, the coefficient of static friction μ on these contact surfaces is approximately 0.1 to 1.5, preferably 0.1 to 1.0. During the firing process, the support member 15 can be smoothly slid and moved. On the other hand, if the surface roughness of these contact surfaces exceeds 5 μm, the support members 15A, 15B, and 15C cannot smoothly slide and move with each other, which accompanies the sintering shrinkage of the cylindrical ceramic molded body 16. It becomes difficult to suppress the deformation. The surface roughness Ra of the support member 15 can be measured by a surface roughness measuring device.

The support member 15 is required to have a cylindrical ceramic molded body 16 placed on the support member 15 and stably support the support member 15. Therefore, the support member 15 needs to be arranged at three or more locations. Four or more locations are more preferable, and six or more locations are more preferable. However, if the support members 15 are installed in too many places, they interfere with each other when they slide and move, so it is preferable to limit the number to about 10 or less.

It is desirable that the number of the support members 15 to be stacked is 3 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 will become unstable against shaking, so it is appropriate to keep the height to 30 mm or less.

The shape of the support member 15 is preferably a flat plate. The shape of the flat plate in the length and width direction is not so limited, but it is sufficient that the flat plate has a size that does not fall due to slippage when sliding and moving in the cylindrical radial direction together with sintering shrinkage. Moreover, since it does not move in the circumferential direction of the cylinder, it is sufficient that the width is sufficient for stacking. 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, when the weight of the molded body becomes heavier, the support member bites into the molded body more strongly, and the sintered body remains in the recessed shape. May become. In that case, in the subsequent grinding process, a processing allowance for removing the amount must be provided. Therefore, by using a flat plate instead of a round bar or a square bar, the amount of dents caused by the support member biting into the molded body can be suppressed to 0.3 mm or less. The shape of the flat plate-shaped support member may be rectangular, but may be circular or polygonal as long as it does not slip off during sintering shrinkage. Further, the support members to be stacked do not necessarily have the same shape.

For example, in the case of a flat rectangular plate, the width is preferably about 15 mm to 30 mm and the length is preferably about 20 mm to 60 mm. If it is a disk-shaped plate, it is preferably about φ20 mm to 60 mm. The amount of dent due to biting depends on the material and height of the cylinder and the sintering temperature, but for ceramics with a height of about 500 mm such as ITO and AZO mentioned as examples, a width of a support member of 15 mm or more is sufficient. is there. If the thickness is too thin, it is easily cracked, and it is desirable that the thickness is 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 low cost, the flat plate-shaped support member 15 may be as thin as 0.5 mm to 5 mm.

(1-3. Baking process)
The firing step S3 is a step of firing the cylindrical ceramic molded product 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 product should be appropriately selected according to its composition, size, characteristics of the firing furnace, etc., and are not particularly limited, but in general, firing can be performed under the following conditions. it can.

a) Binder removal stage In the firing step, the organic components contained in the cylindrical ceramic molded product are first heated from room temperature to a specific temperature (binder temperature) over a certain period of time (binder time). It is necessary to remove.

The binder 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 component contained in the cylindrical ceramic molded product can be sufficiently removed.

During the binder removal stage, it is necessary to supply the atmospheric gas at 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 or oxygen or any mixed gas thereof.

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

The firing temperature varies depending on the composition of the cylindrical ceramic molded product, but for example, when indium oxide is the main component, it is preferably 1200 ° C. to 1600 ° C., from the viewpoint of obtaining a high-density cylindrical ceramics sintered body. Therefore, it is more preferable to set the temperature from 1300 ° C to 1600 ° C. On the other hand, when zinc oxide is the main component, the temperature 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 at the sintering stage differs depending on the composition of the cylindrical ceramic molded product, but depending on the composition, the atmosphere, oxygen, or a mixed gas thereof is preferably 100 L / min to 600 L / min per ^{1 m 3 of the furnace volume.} Supply 200 L / min to 400 L / min.

<2. Cylindrical ceramic sintered body ＞
The cylindrical ceramic sintered body according to the embodiment of the present invention is obtained by uniformly firing while suppressing deformation of the cylindrical ceramic molded body. For example, it can be obtained by the above-mentioned manufacturing method. Such a cylindrical ceramic sintered body is characterized by having excellent dimensional accuracy. Specifically, by using a plurality of support members, the sintering shrinkage is not fixed and is freely shrunk during 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 flat, 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 dent due to the biting can be suppressed to 0.3 mm or less. As described above, the cylindrical ceramic sintered body according to the embodiment of the present invention is a sintered body having excellent dimensional accuracy.

The amount of deformation is measured as follows. The cylindrical ceramic sintered body according to the 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 face on the ground side. Δd (= dmax−dmin) is 1.5 mm or less. Here, at the four positions in the circumferential direction, the first inner diameter is determined by a straight line passing through the center of the cylindrical ceramic sintered body, and the inner diameters on the straight line at which the straight lines are out of phase by 45 ° are sequentially arranged. The measurement may be performed, and when the number of measurement points is increased, the angle at which the phase shifts may be determined according to the number of measurement points.

The amount of dent was defined as the maximum depth at the position where the support member was in contact, with reference to the surface on which the support member was not in contact. If there are a plurality of positions where the support members are in contact with each other, the average value thereof is taken as the bite amount. In addition, the measuring method is to measure using a depth gauge.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

In the following Examples and Comparative Examples, the characteristics of the obtained cylindrical ceramic sintered body were evaluated according to the following evaluation items. As an evaluation method, one sintered batch was produced by repeating 8 pieces / batch × 5 times (40 pieces in total), and the number of deformation amounts 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 mixed and crushed by a bead mill (manufactured by Ashizawa Finetech Co., Ltd.). By doing so, a slurry was formed.

Next, this slurry was spray-dried with a spray dryer (Okawara Kakohki Co., Ltd., ODL-20 type) to obtain spherical granulated powder. When the tap density of this granulated powder was measured using a shaking specific gravity measuring instrument (KRS-409 manufactured by Kuramochi Kagaku Kikai Seisakusho), it was confirmed that it was ^{1.5 g / cm 3.}

[Molding process]
After filling this granulated powder into a cylindrical rubber mold, it is put into a cold hydrostatic press device, and pressure molding is performed 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 molded bodies having a total length of 350 mm were produced.

[Baking process]
Eight cylindrical ceramic molded body obtained in the molding step, the inner diameter 40 mm (opening area: 12.6 cm ²⁾ atmospheric pressure firing furnace furnace volume of 0.5 m ³ with eight of the atmospheric gas supply port It was placed in (manufactured by Marusho Electric Co., Ltd.) and fired.

First, for each of the cylindrical ceramic molded bodies, ^{an alumina floor plate having an inner diameter of 30 mm (opening area: 7.1 cm 2} ), a length of 250 mm, a width of 250 mm, and a thickness of 5 mm was prepared, and the floor plate was prepared. Were installed on the hearth. Next, around the vents, as support members, a total of 24 alumina flat plates having a width of 15 mm, a total length of 50 mm, and a height of 1 mm were placed in three stages at eight locations, and the longitudinal direction thereof was centered on the vents. They were arranged so as to coincide with the radial direction of the circle centered on the ventilation holes and radially. At this time, the flat plates were arranged at approximately equal intervals in the circumferential direction. Subsequently, the cylindrical ceramic molded body was placed upright on the support member so that the cylindrical shaft coincided with the center of the ventilation hole. In this example, as the support member, a surface roughness measuring device (manufactured by Mitutoyo Co., Ltd., Surftest 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 in the atmospheric firing furnace through the atmospheric gas supply port. Removed the binder. After that, the ^{temperature was raised to 1350 ° C. while oxygen was flowing at 300 L / min per 1 m 3 of} the furnace volume, and the temperature was maintained at this temperature (baking temperature) for 20 hours to sinter the cylindrical ceramic molded product. Eight cylindrical ceramic sintered bodies were produced. These cylindrical ceramic sintered bodies were taken out from the furnace and the amount of deformation thereof was measured.

The above procedure was repeated 5 times to prepare a total of 40 cylindrical ceramic sintered bodies. At this time, the number of deformation amounts of 1.5 mm or more 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. .. Further, a spherical granulated powder was obtained in the same manner as in Example 1 except that the shape of the cylindrical ceramic molded body was 200 mm in outer diameter, 160 mm in inner diameter, and 330 mm in total length. The tap density of this granulated powder was 1.5 g / cm ³ . Each of the cylindrical ceramic compacts was installed on a hearth having a ventilation hole with an inner diameter of 30 mm (opening area: 7.1 cm ^{2) via a support member.} Further, 40 cylindrical ceramic sintered bodies were produced in the same manner as in Example 1 except that the binder removal temperature was set to 500 ° C. and the firing temperature was set to 1550 ° C. The results are shown in Table 1.

(Example 3)
In Example 3, the number of stages of the support member was set to 5. 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, as the support member, a 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 had a surface roughness of 5 μm with an 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 stages of the support member was set to 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 stages of the support member was set to 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, a support member made of zirconia and 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 6)
In Comparative Example 6, a columnar support member (1 step) 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 (1 step) 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 in contact with the support member had a surface roughness equivalent to that of the support member. In addition, when it was repeated, the support member was installed as it was.

For each of the above Examples and Comparative Examples, the amount of deformation of 40 cylindrical ceramic sintered bodies was measured, and the number of the amount of deformation of 1.5 mm or more at that time was counted. In addition, the amount of dent was measured. The results are shown in Table 1.

From Table 1, it can be seen that in the examples, the number of deformations exceeding 1.5 mm is 0, the shape and dimensions of the sintered body are good, and the dimensional accuracy is maintained even after repeated 5 times. In the comparative example, as shown in Comparative Example 2, when there is only one support member and the frictional resistance is large and slip does not occur, it can be seen that the amount of deformation is large. Further, when the surface roughness of the support member exceeds Ra 5 μm, the frictional resistance becomes large, and a sintered body having a deformation amount of more than 1.5 mm is partially generated. As for the amount of dents in the sintered body, since a flat plate support member was used, no dents of 0.3 mm or more were generated.

11 Hearth, 12 (hearth) vents, 13 floorboards, 14 (bedboard) vents, 15 (15A, 15B, 15C) support members, 16 cylindrical ceramic moldings

Claims (4)

A method for manufacturing a cylindrical ceramics sintered body in which a cylindrical ceramic molded body is fired using a firing furnace.
A molding process in which a raw material powder is filled in a cylindrical cavity and pressure-molded to obtain a cylindrical ceramic molded body.
An arrangement step of arranging the cylindrical ceramic molded body in the firing furnace, and
It has a firing step of calcining the arranged cylindrical ceramic molded body in the firing furnace to obtain a cylindrical ceramics sintered body.
In the arrangement step, a plurality of support members made of a ceramics sintered body having a surface roughness of 5 μm or less in arithmetic average roughness Ra are arranged on the hearth in the firing furnace or a floor plate installed on the hearth. The support member has two or more layers of contact surfaces having a static friction coefficient μ of 0.1 to 1.0 by stacking three or more stages at one location, and the cylindrical ceramics is placed on the support member. Place the molded product upright and place it upright .
The obtained cylindrical ceramics sintered body has a 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 contact surface side of 1.5 mm or less and is a support member during firing. A method for manufacturing a cylindrical ceramics sintered body in which the recess of the contact surface is 0.3 mm or less. 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 producing a sintered body according to claim 2, wherein the thickness of the support member is 0.5 mm or more and 5 mm or less. 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.

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