JP4142499B2 - Method for producing ceramic sintered body having continuous porous layer and dense layer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a ceramic sintered body in which a porous layer is formed on the surface of a dense ceramic substrate, and more specifically, sintering in which pores in a porous layer communicate with each other. The present invention relates to a method for manufacturing a body.
[0002]
The ceramic sintered body obtained by the production method of the present invention can be suitably used as a biomaterial member having biocompatibility such as an artificial bone, an artificial joint, and an artificial tooth root.
[0003]
[Prior art]
Along with the development of biotechnology, in the field of orthopedics and dental treatment, the treatment of embedding an implant member in bone tissue has become widespread, and the material of the implant member has good affinity with bone tissue and is toxic. Ceramics are widely used because they are not.
[0004]
Since such an implant member has a porous structure suitable for bone tissue growth and is required to have high strength, the structure of the implant member is formed on the surface of a dense ceramic substrate with a porous ceramic layer. Attempts have been made to achieve both the above porous structure and strength by adopting a two-layer structure in which is laminated. If a dense ceramic substrate without a porous ceramic layer is used alone as an implant member, bone tissue growth and biocompatibility in vivo will be insufficient, while only porous ceramics are used. This is because the base material made of is insufficient in strength.
[0005]
Various methods have been proposed for producing a ceramic sintered body having a porous layer and a dense layer. For example, Patent Document 1 proposes a method in which the surface of a core portion made of a ceramic sintered body is covered with a ceramic material containing a foaming agent and then the whole is sintered. Further, in Patent Document 2, a ceramic raw material slurry is applied to the surface of a porous sintered ceramic base material having continuous spherical open pores formed by stirring and foaming, and this applied layer has an immature porous body. A method of sintering so as to be in a sintered state has been proposed. However, if the sintered ceramic is used as a base material, and the ceramic raw material slurry is applied to the surface of the base material and then sintered, the above method has a poor affinity between the base material and the coating layer, so the coating layer is easy to peel off. The ceramic substrate and the porous layer cannot be firmly integrated.
[0006]
On the other hand, Patent Document 3 proposes a method for producing a ceramic intraosseous implant member in which a ceramic raw material powder and a burnable material that can be burned off during the firing process of the ceramic are mixed and then molded and then heated and fired. . However, since the entire implant member obtained by this method is porous, the strength is insufficient.
[0007]
By the way, a porous layer is provided on the surface of the implant member, and an opening exists on the outermost surface. Bone grows from the opening into the porous layer, thereby providing an anchor effect and improving adhesion to the living body. Therefore, if pores in the porous layer are communicated with each other, it is considered that bone grows also in the communicating portion, exhibits a bridging effect, and has higher adhesion with a living body. However, in the method described in the above-mentioned literature, most of the pores inside the porous layer are likely to be independent, and it is difficult to obtain one in which the pores communicate with each other.
[0008]
[Patent Document 1]
Japanese Laid-Open Patent Publication No. Sho 62-14846 (see “Claims” etc.)
[Patent Document 2]
JP 2002-121086 A (refer to [Claims] etc.)
[Patent Document 3]
Japanese Laid-Open Patent Publication No. 51-116809 (see “Claims” etc.)
[0009]
[Problems to be solved by the invention]
The present invention has been made in view of such a situation, and an object of the present invention is a ceramic sintered body having a two-layer structure in which a porous layer is formed on the surface of a dense ceramic base material. The adhesion between the layer and the ceramic base material is good, high strength can be achieved, and the pores existing in the vicinity of the interface between the porous layer and the ceramic base material communicate with each other. The object is to provide a method capable of reliably producing a body.
[0010]
[Means for Solving the Problems]
The method for producing a ceramic sintered body having a continuous porous layer and a dense layer according to the present invention that has solved the above-mentioned problems is a method for producing a ceramic sintered body having a continuous porous layer and a dense layer. The ceramic raw material powder and the mixed powder layer containing the burnable pore forming agent and the ceramic raw material powder layer made of the same or different ceramic raw material powder as the ceramic raw material powder are laminated via the burnable fiber material, A step of molding the fiber material in contact with the burnable pore-forming agent, a step of burning off the burnable pore-forming agent and the burnable fiber material in the resulting molded body, and further sintering the ceramic raw material powder It has a gist in the point including the process to make. It is preferable that the mixed powder layer further includes a burnable short fiber, and the burnable short fiber and the burnable pore forming agent are in contact with each other.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The present inventors have studied from various angles in order to solve the above problems. As a result, when the ceramic sintered body is manufactured, the mixed powder layer and the ceramic raw material powder layer are laminated via the burnable fiber material, and the burnable fiber material and the burnable pore forming agent are brought into contact with each other. It has been found that if the sintering is performed, the pores in the porous layer can be reliably communicated with each other, and the above problem can be solved brilliantly, thereby completing the present invention.
[0012]
That is, in the method for manufacturing a ceramic sintered body according to the present invention, it is important to include the following steps (1) to (3).
(1) Laminating a mixed powder layer containing a ceramic raw material powder and a burnable pore-forming agent, and a ceramic raw material powder layer made of a ceramic raw material powder that is the same as or different from the ceramic raw material powder via a burnable fiber material, Forming in a state where the burnable fiber material and the burnable pore forming agent are in contact with each other;
(2) a step of burning off the burnable pore-forming agent and the burnable fiber material in the obtained molded body,
(3) A step of further sintering the ceramic raw material powder.
[0013]
Hereinafter, it demonstrates in detail along each process.
[0014]
First, in carrying out the step (1), the procedure for laminating the mixed powder layer and the ceramic raw material powder layer via a burnable fiber material is not particularly limited. For example, the procedure shown in FIG. Can be laminated.
[0015]
FIG. 1 shows an example of a procedure for laminating a mixed powder layer, a burnable fiber material, and a ceramic raw material powder layer, and shows two procedures (a) and (b). In the figure, 1 is a ceramic raw material powder, 1a is a ceramic raw material powder layer, 2 is a burnable pore forming agent, 3 is a mixed powder layer, 4 is a burnable fiber material, 5 is a continuous porous layer, and 6 is a dense ceramic layer. (Dense layer), 7 is a ceramic sintered body, 8 is a pore, and 9 is a communicating portion.
[0016]
In the procedure of FIG. 1A, first, (a-1) a mixed powder layer 3 in which ceramic raw material powder 1 and burnable pore forming agent 2 are mixed is formed, and then (a-2) a burnable fiber material is formed on this surface. 4, (a-3) a ceramic raw material powder layer 1 a made of a ceramic raw material powder is laminated.
[0017]
On the other hand, in the procedure of FIG. 1B, first, (b-1) the ceramic raw material powder layer 1a made of the ceramic raw material powder is formed, and then (b-2) after the surface is coated with the burnable fiber material 4, (B-3) The mixed powder layer 3 in which the ceramic raw material powder 1 and the burnable pore forming agent 2 are mixed is laminated.
[0018]
Then, the laminate thus obtained is formed into an arbitrary shape (not shown) in a state where the burnable fiber material and the burnable pore forming agent are in contact with each other, and then the burnable fiber material and the burnable pore formation are formed as described later. When the agent is burned out and sintered, a ceramic sintered body 7 having a continuous porous layer 5 and a dense layer 6 can be manufactured as shown in (a-4) and (b-4) of FIG. That is, when the mixed powder layer 3 and the ceramic raw material powder layer 1 a are laminated via the burnable fiber material 4, the burnable pore forming agent 2 and the burnable fiber material 4 included in the mixed powder layer 3 come into contact with each other. When the laminated body is molded into a desired shape in such a contact state, when the molded body is heated, the burnable pore-forming agent 2 dispersed in the mixed powder layer 3 is burned out and pores 8 are formed. The burnable fiber material 4 that is in contact with the burnable pore forming agent 2 is also burned away, and a communicating portion 9 that connects the pores 8 is formed. As a result, the mixed powder layer 3 becomes the communication porous layer 5 in which the pores 8 are connected by the communication part 9.
[0019]
Here, when the fired fiber material interposed between the mixed powder layer and the ceramic raw material powder layer is heated and sintered, the adhesion between the resulting porous layer and the dense layer is slightly deteriorated, The porous layer may peel from the dense layer. Therefore, in the procedure shown in FIG. 1 (a), a ceramic raw material powder layer (not shown) is first provided, and the mixed powder layer 3 shown in (a-1) is provided thereon. In the procedure shown in b), if a ceramic raw material powder layer (not shown) is further provided on the mixed powder layer 3 shown in (b-3), the mixed powder layer is sandwiched between the ceramic raw material powder layers. Since it will be in a state, expansion | swelling and aggregation of the mixed powder layer at the time of shaping | molding are suppressed, As a result, peeling of a porous layer can be suppressed. Then, the ceramic raw material powder layer (dense layer) formed on the surface of the mixed powder layer (porous layer) after the sintering is mechanically polished, whereby the ceramic sintered body having a continuous porous layer having an opening on the surface and a dense layer. You can get a body.
[0020]
Although FIG. 1 shows an example in which only one mixed powder layer is provided on the surface of the ceramic raw material powder layer, two or more mixed powder layers may be provided. In this case, if a burnable fiber material is provided between the mixed powder layers, more pores can be communicated with each other.
[0021]
Examples of the ceramic raw material powder include zirconia, alumina, apatite, calcium phosphate, bioglass, and crystallized glass. These can be used alone or in combination of two or more.
[0022]
In particular, the zirconia includes CeO.₂Or Y₂O_ThreeContaining tetragonal ZrO as stabilizer₂When powder is used, the obtained ceramic sintered body has high strength and can be suitably used.
[0023]
CeO₂Containing ZrO₂Powder (sometimes referred to as “Ce-TZP”) has a low threshold value for causing phase transformation and induces phase transformation at a relatively low stress, and therefore becomes a ceramic layer exhibiting high fracture toughness. On the other hand, Y₂O_ThreeContaining ZrO₂Since the powder (sometimes referred to as “Y-TZP”) undergoes a phase transformation from tetragonal to monoclinic crystal, which is a metastable phase at the crack tip in the stress field, and the fracture energy is relaxed, High strength.
[0024]
As Ce-TZP, CeO₂ZrO containing 8-15 mol%₂Powder is preferable, and Y-TZP includes Y₂O_ThreeContaining 2 to 5 mol% of ZrO₂A powder is preferred.
[0025]
Ce-TZP and Y-TZP can be used alone, but it is recommended to use them together. This is because Ce-TZP mainly contributes to toughness and phase transformation suppression, and Y-TZP mainly contributes to strength. By using these together, a higher strength and higher toughness ceramic layer is obtained. When these are used in combination, the volume ratio of Ce-TZP and Y-TZP is preferably 9: 1 to 6: 4, more preferably 8: 2 to 7: 3. .
[0026]
For the zirconia, further Al₂O_ThreeIt is effective to add ZrO₂Combining with powder contributes to higher strength. For that purpose, ZrO₂Al in the powder₂O_ThreeIt is desirable to uniformly disperse. Al₂O_ThreeThe mixing ratio is not particularly limited, but if it is too large, it becomes difficult to uniformly disperse in the zirconia powder.₂It is good to keep it to 20 volume% or less with respect to powder.
[0027]
For the zirconia, the Al₂O_ThreeIn addition to or in addition to this, the toughness of the ceramic sintered body can be achieved by adding MgO or CaO. MgO and CaO act as a sintering aid to increase density and improve toughness. In order to effectively exhibit such effects, it is necessary to uniformly disperse a trace amount of MgO and CaO, and the blending ratio is ZrO.₂It is good to keep it to 3.0 volume% or less with respect to powder. The addition form is not limited to MgO or CaO as long as the purity is 2N or more._ThreeAnd Mg (OH)₂, CaCO_Three, Ca (OH)₂Etc.
[0028]
The ceramic raw material powder used for the mixed powder layer and the ceramic raw material powder layer may be the same or different.
[0029]
In addition, the ceramic raw material powder can be used as primary particles indicating the powder itself, but assuming a case where it is put into practical use as a molded body having an arbitrary shape, it includes a binder granulated and dried by a spray dryer or the like. It is preferable to use secondary particles.
[0030]
The material of the burnable pore forming agent is not particularly limited as long as it is a combustible material that burns down at a temperature lower than the sintering temperature, but it is desirable to use a combustible material that burns down at 800 ° C. or lower. Since the sintering temperature of general ceramics is about 1300 to 1600 ° C, if a material with a burning temperature of 800 ° C or less is used as the material for the burnable pore-forming agent, it will be burnt down in the sintered ceramic body after sintering. This is because no pore-forming agent remains. It is more preferable to use a material having a sintering temperature of 500 ° C. or lower.
[0031]
Specific examples of the material for the burnout pore forming agent include thermoplastic polymers such as nylon, polyvinyl alcohol, polyester, acrylic resin, polyethylene, and paraffin. These may be used alone or in combination of two or more. Can be used.
[0032]
The shape of the burnable pore forming agent is not particularly limited, and a flat shape having a ratio of the major axis to the minor axis of less than 3 or a pellet or spherical shape can be suitably used.
[0033]
The size of the burnable pore forming agent may be arbitrarily selected in consideration of the size of the pores formed in the porous layer, but if the shape is spherical, the particle size is about 0.1 to 2 mm. What is necessary is just to use.
[0034]
The burnable pore forming agent may be a single material or a combination of a plurality of materials having different particle diameters in any case where two or more materials are used in combination. By using burnable pore formers with different particle sizes, relatively small burnable pore formers enter between relatively large burnable pore formers, so that relatively large burnable pore formers can be combined. This is because it becomes easy to obtain a ceramic sintered body that communicates with and communicates with pores.
[0035]
The ratio of the ceramic raw material powder and the burnable pore forming agent in the mixed powder layer is not particularly limited, but if the amount of the burnable pore forming agent is excessively increased, the porosity of the porous layer becomes too high and the strength decreases. Therefore, the mixing ratio (ceramic raw material powder: burnable pore forming agent) is preferably about 8: 2 to 4: 6 in volume ratio.
[0036]
As the material of the burnable fiber material, the same material as the material of the burnable pore forming agent can be used, and in addition to those exemplified above, a nonwoven fabric can also be used. That is, it is not particularly limited as long as it is a combustible material that burns away at a temperature lower than the sintering temperature. It is desirable to use a combustible material that burns down at 800 ° C. or lower, more preferably 500 ° C. or lower. The burnable fiber material and the burnable pore forming agent may be the same material or different materials.
[0037]
As the burnout fiber material, it is desirable to use a fibrous material having a ratio of a major axis to a minor axis of 3 or more, or a net-like material formed by intertwining fibers. That is, by disposing a fibrous or reticulated burnable fiber material between the mixed powder layer and the ceramic raw material powder layer, the burnable pore forming agents contained in the mixed powder layer are cross-linked by the burnable fiber material. This is because the pores can communicate with each other by heating and burning the burnable material while maintaining this state.
[0038]
As the shape of the fibrous burnable fiber material, it is sufficient that the ratio of the major axis to the minor axis is 3 or more. However, if the fiber diameter is too large, the communicating part that connects pores becomes coarse and porous. On the other hand, if the fiber strength is too small, the communicating portion disappears during sintering and the pores cannot communicate with each other. From this viewpoint, the fiber diameter is preferably about 0.01 to 0.3 mm.
[0039]
In the production method of the present invention, it is more preferable to use a net-like material in which fibrous burnable fiber materials are intertwined as the burnable fiber material. This is because if the burnable fiber material is formed in a net shape in advance, handling properties and lamination workability are improved.
[0040]
The size of the mesh is preferably adjusted in consideration of the size of the burnable pore forming agent. That is, when a mixed powder layer and a ceramic raw material powder layer are laminated via a burnable fiber material, if a burnable fiber material whose mesh is smaller than the diameter of the burnable pore forming agent is used, the contact between the raw material powders This is because the area is reduced and the strength of the interface is lowered. Preferably, a burnable fiber material having a mesh size of 0.2 mm square or more may be used. However, if the mesh is too larger than the diameter of the burnable pore-forming agent, the burnable pore-forming agent and the burnable fiber material are difficult to contact, and it is difficult to form a desired communication portion. The upper limit may be determined in consideration of the size of the burnable pore forming agent and the form of the communicating part to be formed.
[0041]
The net shape is not particularly limited, and for example, it may be used even if the fiber intersects with a swell or a part of the fiber constituting the net is swelled. Can do. By burning out these bulges, the same effect as the above-mentioned burnout pore forming agent is obtained. That is, the shape having a bulge can serve both as the burnout pore forming agent and the burnout fiber material.
[0042]
When a fibrous burnable fiber material is interposed between the mixed powder layer and the ceramic raw material powder layer, the fibrous burnable fiber material is uniformly distributed on the surface of the mixed powder layer 3 and the ceramic raw material powder layer 1a. It can be dispersed by swinging as you do. On the other hand, when the net-like burnable fiber material is interposed, the surface of the mixed powder layer 3 or the ceramic raw material powder layer 1a may be covered with the net-like burnable fiber material. The state interposed in this way is shown in FIG. 1 (a-2) and (b-2).
[0043]
In the production method of the present invention, it is preferable to further mix burnt short fibers into the mixed powder layer. This is because the burnable pore forming agent communicates with each other via the burnable short fibers by mixing the ceramic raw material powder and the burnable pore forming agent in addition to the burnable short fibers. The kind and shape of the material of the burnable short fiber can be the same as those of the fibrous burnable fiber material.
[0044]
In the mixed powder layer, the net-like burnable fiber material may be mixed. This is because if a net-like burnable fiber material is mixed in the mixed powder layer, the burnable pore-forming agents in contact with the mesh communicate with each other. In this case, it is necessary to use a net-like burnable fiber material having a mesh larger than the diameter of the burnable pore forming agent.
[0045]
Next, the obtained laminate is molded.
[0046]
The molding method is not particularly limited, and press molding or CIP molding can be employed. The molding pressure is 19.6 to 196 MPa (200 to 2000 kg / cm²) Is preferable. If necessary, the obtained molded body may be processed, but in order to simplify the processing step, it is preferable to use a mold having a shape close to the shape of the final product.
[0047]
The molded body thus obtained has a temperature at which the burnout pore forming agent and the burnout fiber material (hereinafter, collectively referred to as “burnout material”) are burned out in the step (2). Heat to the above to burn off the burnable material. That is, in the production method of the present invention, the compact containing the burnable material is not heated and sintered until it is sintered, but the burnable material is burned down in advance in a temperature range lower than the sintering temperature. It is important to sinter. This is because if the compact containing the burnable material is heated and sintered rapidly, the burnable material becomes excessively gasified and the compact is excessively expanded. Moreover, it is because there is a concern that the gas component generated when the burnable material burns out cannot be completely removed from the molded body and remains inside the molded body.
[0048]
The temperature at which the burnout material is burned out is not particularly limited as long as the material is burnt down completely, but it is necessary to make it lower than the sintering temperature. Accordingly, the temperature at which the burnable material is burned out varies depending on the type of burnout material, but it may be heated to a temperature range of about 200 to 800 ° C. and held in this temperature range for a predetermined time. When the heating temperature is less than 200 ° C., the burnout material may not be completely burned out. On the other hand, when the heating temperature is higher than 800 ° C., shrinkage due to sintering starts near the sintering temperature, so that pores are hardly formed.
[0049]
The burnable material is burned down if heated to a temperature exceeding the burnout temperature, but in order to carry out degreasing of the ceramic raw material powder, it is preferable to hold it in the temperature range for at least about 1 hour, It is more preferable to hold for about 4 hours.
[0050]
When heating the obtained molded body, it is preferable to gently heat to the above temperature range. This is because if the heating rate is reduced and the heating is performed slowly, the burnable material gradually burns and burns away, so that rapid expansion can be avoided. Specifically, the heating rate from room temperature to the above temperature range is preferably 100 ° C./hour or less, more preferably 60 ° C./hour or less. However, if the heating rate is too small, the productivity is lowered, so an appropriate rate is set.
[0051]
In the molded body in which the burnable material is burned off, the ceramic raw material powder is heated and sintered in the step (3).
[0052]
The conditions at the time of sintering are not particularly limited, and may be performed by adopting conditions such as a sintering temperature and a sintering atmosphere suitable for the raw material powder used. For example, the sintering temperature may be about 1300 to 1600 ° C. Further, it is preferable to perform hot isostatic pressing (HIP) in a capsule-free manner after sintering, so that the base material becomes denser and the strength of the entire sintered body is improved. As the pressurizing condition, for example, it is preferably performed at about 49 to 196 MPa.
[0053]
By the way, the burning step (2) and the sintering step (3) may be performed continuously, but may be performed batchwise. That is, after heating up to a temperature range where the burnable material is burnt out and holding it in this temperature range for a predetermined time, it may be subsequently heated to the sintering temperature for sintering, or after the burnable material is burned down, It may be cooled and then heated and sintered again.
[0054]
Regarding the ceramic sintered body obtained after sintering, the thickness of the porous layer is not particularly limited and may be appropriately determined according to the use, but is preferably about 0.1 to 5 mm. If the porous layer is thinner than 0.1 mm, the effect is hardly exhibited. On the other hand, if the porous layer is too thick, the sintered body as a whole may have insufficient strength.
[0055]
In addition, the porosity of the porous layer is preferable because the higher the porosity, the more easily bones invade, but when the area ratio of the pores (openings) exceeds 75% when the cross section of the sintered body is observed with a microscope, Since the strength as a sintered body is lowered, it is preferable to control the porosity to be 75% or less. On the other hand, if the porosity is too low, the biocompatibility is insufficient and the bonding strength with the bone is reduced. From such a viewpoint, the porosity is preferably 25% or more.
[0056]
A larger pore diameter in the porous layer is preferable because bone easily penetrates into the porous layer. However, when the pore diameter is too large, the strength as a sintered body is lowered. From such a viewpoint, it is preferable to control the pore diameter to be mainly about 200 to 1500 μm. The main body means that 50% or more of the number of pores recognized when the cross section of the sintered body is observed is within the above range. Of course, it does not matter if the pore diameter is outside the above range.
[0057]
If the path diameter (tunnel diameter) that connects the pores is too large, stress may concentrate on the interface between the porous layer and the dense layer, and the porous layer may peel off from the dense layer. It becomes difficult for bones to enter, and it becomes difficult to obtain the effect of communicating the pores. From such a viewpoint, it is preferable to control the average path diameter to be about 10 to 300 μm. A more preferred lower limit is about 30 μm and an upper limit is about 100 μm.
[0058]
The porosity and pore diameter of the porous layer can be controlled by adjusting the form and amount of the burnable pore forming agent mixed with the ceramic raw material powder. The path diameter can be controlled by adjusting the form of the burnable fiber material.
[0059]
In the ceramic sintered body obtained by the manufacturing method of the present invention, pores existing in the porous layer are in communication with each other, and bone can enter the communication portion to increase the adhesion strength. It can be suitably used as a biomaterial member having affinity. Examples of the biomaterial member include an artificial bone, an artificial joint, and an artificial tooth root.
[0060]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are not intended to limit the present invention, and may be implemented with appropriate modifications within a range that can meet the purpose described above and below. These are all possible and are within the scope of the present invention.
[0061]
Example 1
CeO as ceramic raw material powder₂Containing 10 mol% of ZrO₂80% by volume of powder and Y₂O_ThreeZrO containing 3 mol%₂Mixed ZrO mixed with 20% by volume of powder₂90% by volume of powder, Al₂O_Three10 volume% was used.
[0062]
Acrylic beads (average particle size: 1 mm) were used as the burnout pore forming agent.
[0063]
The ceramic raw material powder and the acrylic beads were mixed at a volume ratio of 6: 4, and this was dry mixed with a V-type mixer for 1 hour to obtain a mixed powder.
[0064]
The obtained mixed powder was put into a mold of a uniaxial press machine to form a mixed powder layer.
[0065]
Next, the surface of the mixed powder layer is covered with a polyethylene mesh (fiber diameter: 200 μm, mesh size: 1 mm square) as a burnable fiber material, and a ceramic raw material powder layer made of the ceramic raw material powder is formed thereon. Were laminated. The obtained laminate was 49 MPa (500 kg / cm²) And press-molded with 1.5t / cm²Was formed by cold isostatic pressing.
[0066]
The obtained molded body was heated in the atmosphere from room temperature to 500 ° C. at a heating rate of 60 ° C./hour, held at this temperature for 3 hours, and then cooled to room temperature.
[0067]
The molded body after cooling was heated to 1450 ° C. in the atmosphere, and held at this temperature for 2 hours for sintering.
[0068]
The sintered ceramic body obtained by sintering was cut and the cross section was ground with a flat polishing machine, and then the surface was mirror-finished with 3 μm diamond abrasive grains.
[0069]
The mirror-finished surface was observed by attaching a digital camera for microscopes manufactured by Nikon Instec to a real microscope, and a dense layer and a porous layer were observed. The thickness of the porous layer was approximately 1 mm. The average pore diameter of these pores was 800 μm. Moreover, the pores existing in the vicinity of the interface between the dense layer and the porous layer were in communication with each other.
[0070]
Example 2
In Example 1, the burnout pore-forming agent was used except that acrylic beads having an average particle diameter of 1 mm and acrylic beads having an average particle diameter of 300 μm were mixed at a volume ratio of 9: 1. A ceramic sintered body was produced under the same conditions as in Example 1.
[0071]
The cross section of the ceramic sintered body obtained by sintering was observed with a microscope in the same manner as in Example 1. As a result, a dense layer and a porous layer were observed, the thickness of the porous layer was about 1 mm, and the pores observed in this porous layer were mainly those having a pore diameter of 800 μm. The pores existing in the vicinity of the interface between the dense layer and the porous layer communicated with each other.
[0072]
Comparative example
In Example 1 above, a ceramic sintered body was produced under the same conditions as in Example 1 except that the ceramic powder layer was laminated without covering the surface of the mixed powder layer with a polyethylene mesh.
[0073]
When the cross section of the ceramic sintered body obtained by sintering was observed with a microscope in the same manner as in Example 1, a dense layer and a porous layer were observed, and the thickness of the porous layer was about 1 mm. The average pore diameter observed in 1 was 800 μm. However, the pores existing in the vicinity of the interface between the dense layer and the porous layer were not communicated with each other.
[0074]
【The invention's effect】
According to the present invention, a ceramic sintered body having a two-layer structure in which a porous layer is provided on the surface of a dense ceramic substrate, the adhesion between the porous layer and the ceramic substrate is good, and the strength is high Furthermore, it was possible to provide a method capable of reliably producing a ceramic sintered body in which pores existing in the vicinity of the interface between the porous layer and the ceramic base material communicate with each other.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an example of a procedure for laminating a mixed powder layer, a burnable fiber material, and a ceramic raw material powder layer.
[Explanation of symbols]
1 Ceramic raw material powder
1a Ceramic material powder layer
2 Burnout pore forming agent
3 Mixed powder layer
4 Burnable fiber material
5 Communicating porous layer
6 Dense ceramic layer (dense layer)
7 Ceramic sintered body
8 pores
9 Communication Department

Claims (2)

A method for producing a ceramic sintered body having a continuous porous layer and a dense layer,
A mixed powder layer containing a ceramic raw material powder and a burnable pore forming agent and a ceramic raw material powder layer made of the same or different ceramic raw material powder as the ceramic raw material powder are laminated via a burnable fiber material, and the burnable fiber Forming the material and the burnable pore-forming agent in contact with each other,
A step of burning out the burnable pore-forming agent and the burnable fiber material in the obtained molded body,
A step of sintering the ceramic raw material powder;
A method for producing a ceramic sintered body having a communicating porous layer and a dense layer. The production method according to claim 1, wherein the mixed powder layer further contains burnable short fibers, and the burnable short fibers are in contact with the burnable pore forming agent.

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