WO2020116568A1 - Ceramic article production method and ceramic article - Google Patents

Abstract

Provided are: a method for producing a ceramic article having a porous part and realizing improvement in mechanical strength of a molded article while obtaining high molding accuracy; and a ceramic article. This production method comprises: (i) a step for forming a powder layer by evenly spreading a powder of metal oxide that contains aluminum oxide as the main component; (ii) a step for melting and solidifying or for sintering the powder by irradiating the powder layer with an energy beam on the basis of shaping data; (iii) a step for causing a liquid that contains a zirconium component to be absorbed by a molded article having a porous part and being formed by repeating steps (i) and (ii); and (iv) a step for heating the molded article that has absorbed the liquid containing the zirconium component, wherein in the absorption step, the liquid is absorbed such that the proportion of the zirconium component among metal components contained in the porous part becomes 0.3-2.0 mol%.

Description

Ceramic article manufacturing method and ceramic article

The present invention relates to a method for manufacturing a ceramics shaped article, and more particularly to a method for manufacturing a ceramics three-dimensional shaped article having a porous structure.

In recent years, in the production of prototypes and small number of parts in a short time, three-dimensional modeling of the direct modeling method in which material powders are combined with an energy beam to obtain a desired model, especially a three-dimensional model The method of manufacturing goods is widespread. The three-dimensional model obtained by the direct modeling method has an advantage that high modeling accuracy can be obtained because the three-dimensional model does not significantly shrink in the subsequent heat treatment. Here, the modeling accuracy in the present invention refers to the difference (rate of change) between the dimension of the ceramic article that has undergone the firing process after modeling and the design dimension designated using CAD or the like. Particularly in the metal field, a powder bed melting method is used to obtain dense and diverse shaped objects. The high density of the metal shaped article is realized by effectively melting and solidifying the metal powder. Based on its success in the metal field, the development of ceramic materials has been discussed and many efforts have been reported. General ceramic materials such as aluminum oxide (Al ₂ O ₃ ) and zirconium oxide (ZrO, ZrO ₂ ) hardly absorb laser light. For this reason, it is necessary to input more energy in order to melt like metal, but it is difficult to obtain the required modeling accuracy because the laser light diffuses and the melting becomes uneven. It was In addition, since the ceramic material has a high melting point, when it is solidified after being melted by laser light, it is rapidly cooled by the atmosphere and the adjacent peripheral portion, and due to the thermal stress generated at that time, many molded objects are obtained. There was a crack. Therefore, the mechanical strength of the obtained modeled product was insufficient.

　Here, porous ceramics are one of the important ceramic members used in various applications. Porous ceramics have excellent heat resistance, chemical resistance, strength characteristics, and light weight. Therefore, by utilizing the fluid (liquid, gas) passage function, various types of filters, separation columns, catalyst carriers, and lightweight structures are used. It is used for materials, heat insulating materials, vacuum chuck members, etc.

Under such circumstances, Non-Patent Document 1 discloses a method for producing a three-dimensional structure by a direct modeling method, in which ceramics having an Al ₂ O ₃ —ZrO ₂ eutectic composition is used to lower the melting point and A technique for reducing the energy required for is disclosed. In addition, in Non-Patent Document 1, while heating ceramic material powder as a raw material with a heater (preliminary heating), laser light is irradiated to alleviate thermal stress and suppress cracking of the obtained modeled object. Is disclosed. According to this manufacturing method, there is an advantage that a dense ceramic structure can be obtained without shrinkage. However, part of the ceramic material powder in the portion not irradiated with laser light is melted by preheating with a heater, and the accuracy of the surface boundary of the structure cannot be obtained. For example, to form a fine porous structure. Was difficult. On the other hand, if the preheating is stopped by giving priority to modeling accuracy, cracks are formed by rapid cooling after the process as described above, and there is a problem that a porous structure having high strength cannot be obtained. Therefore, it is difficult for such a technique to obtain a ceramics shaped article having a porous structure that achieves both shaping accuracy and mechanical strength.

The present invention has been made in view of the above problems, and a method for producing a ceramic article for improving the mechanical strength of a ceramic shaped article having a porous portion, which is produced with high shaping accuracy by making use of the features of the direct shaping method. , And a ceramic article.

One aspect of the present invention is a method for manufacturing a ceramic article, comprising: (i) a step of leveling a powder of a metal oxide containing aluminum oxide as a main component to form a powder layer, and (ii) the powder layer. Modeling having a porous portion formed by repeating a step of irradiating an energy beam based on molding data to melt and solidify or sinter the powder, and (iii) the steps (i) and (ii). A step of absorbing a liquid containing a zirconium component in the object, and (iv) heating the shaped article in which the liquid containing the zirconium component is absorbed. In the absorbing step, the porous portion is included. It is characterized in that the liquid is absorbed so that the ratio of the zirconium component in the metal component contained in is not less than 0.3 mol% and not more than 2.0 mol%.

Another aspect of the present invention is a method for producing a ceramic article, comprising: (i) irradiating a metal oxide powder containing aluminum oxide as a main component with an energy beam based on modeling data to melt the powder. And a step of solidifying or sintering to form a shaped article having a porous portion, (ii) a step of absorbing a liquid containing a zirconium component in the shaped article formed in the step (i), and (iii) A step of heating the shaped article that has absorbed the liquid containing the zirconium component, wherein the zirconium component in the metal component contained in the porous portion has a ratio of 0.3 mol% or more 2 It is characterized in that the liquid is absorbed so as to be 0.0 mol% or less.

Another aspect of the present invention is a ceramic article having a porous part made of a metal oxide containing aluminum oxide as a main component, wherein the zirconium component in the metal component is 0.3 mol in the porous part. % Or more and 2.0 mol% or less.
Further, another aspect of the present invention is a ceramic article made of a metal oxide containing aluminum oxide as a main component and having a dense part and a porous part, wherein zirconium is a metal component contained in the porous part. It is characterized in that the proportion of the component is higher than the proportion of the zirconium component in the metal component contained in the dense portion.

According to the present invention, it is possible to provide a method for manufacturing a ceramic article having a porous portion that achieves high mechanical strength by using a direct molding method, and a ceramic article.

It is an outline sectional view showing typically one embodiment of a manufacturing method of a modeling thing which is a ceramics article of the present invention. It is an outline sectional view showing typically one embodiment of a manufacturing method of a modeling thing which is a ceramics article of the present invention. It is an outline sectional view showing typically one embodiment of a manufacturing method of a modeling thing which is a ceramics article of the present invention. It is an outline sectional view showing typically one embodiment of a manufacturing method of a modeling thing which is a ceramics article of the present invention. It is an outline sectional view showing typically one embodiment of a manufacturing method of a modeling thing which is a ceramics article of the present invention. It is an outline sectional view showing typically one embodiment of a manufacturing method of a modeling thing which is a ceramics article of the present invention. It is an outline sectional view showing typically one embodiment of a manufacturing method of a modeling thing which is a ceramics article of the present invention. It is an outline sectional view showing typically one embodiment of a manufacturing method of a modeling thing which is a ceramics article of the present invention. It is an outline sectional view showing typically one embodiment of a manufacturing method of a modeling thing which is a ceramics article of the present invention. It is an outline sectional view showing typically one embodiment of a manufacturing method of a modeling thing which is a ceramics article of the present invention. It is an outline sectional view showing typically one embodiment of a manufacturing method of a modeling thing which is a ceramics article of the present invention. It is a schematic diagram at the time of seeing the ceramic article of this invention from one surface. It is an optical microscope image of the modeled article which is the ceramic article of the present invention. It is an optical microscope image of the modeled article which is the ceramic article of the present invention. It is a SEM image of the modeling thing which is a ceramics article of the present invention. It is a distribution image of the Zr component of the molded article which is the ceramic article of the present invention. It is a SEM image of the modeling thing which is a ceramics article of the present invention. It is a distribution image of the Zr component of the porous part of the shaped article which is the ceramic article of the present invention. It is a distribution image of the Zr component of the dense portion of the shaped article which is the ceramic article of the present invention. It is a schematic diagram showing typically a piece of composite ceramics parts which consists of a porous part and a dense part concerning the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following specific examples.

A first aspect of the present invention is a method for producing a ceramic article having a porous portion, comprising: (i) leveling a powder of a metal oxide containing aluminum oxide (Al ₂ O ₃ ) as a main component to form a powder layer. And (ii) irradiating the powder layer with an energy beam based on modeling data to melt and solidify or sinter the powder, and (iii) the steps (i) and (). ii) Absorbing a liquid containing a zirconium (Zr) component in a shaped product having a porous portion formed by repeating step ii), and (iv) heating the shaped product absorbed with the liquid containing the zirconium component. And a step of absorbing the liquid such that the ratio of the zirconium component in the metal component contained in the porous portion is 0.3 mol% or more and 2.0 mol% or less in the absorbing step. And

[Direct modeling 3D object]
The present invention is suitable for manufacturing an article using a direct molding method. Among them, the mechanical strength of the porous ceramic article can be greatly improved by combining with a powder bed fusion bonding method or a directional energy lamination method (a so-called cladding method) in which a molding material is piled up.

A basic molding flow of the powder bed fusion bonding method will be described with reference to FIGS. 1A to 1H. First, the powder 101 is placed on the base 130, and the roller 152 is used to form the powder layer 102 (FIGS. 1A and 1B). When the surface of the powder layer 102 is irradiated with the energy beam emitted from the energy beam source 180 while scanning with the scanner unit 181 according to the modeling data, the powder 101 is melted and then solidified to form the solidified portion 103. (FIG. 1C). Next, the stage 151 is lowered to newly form a powder layer 102 on the solidified portion 103 and the unsolidified powder (FIG. 1D). These series of steps are repeated to form the solidified portion 103 having a desired shape (FIGS. 1E and 1F). Finally, the unsolidified powder is removed, and unnecessary parts are removed and the modeled article and the base are separated as necessary (FIGS. 1G and 1H).

Next, the cladding method will be described with reference to FIGS. 2A to 2C. In the cladding method, powder is ejected from a plurality of powder supply holes 202 provided in a cladding nozzle 201, an area where the powder is focused is irradiated with an energy beam 203, and a solidification portion 103 is additionally added to a desired place. Is formed (FIG. 2A), and this step is repeated to obtain a molded article 110 having a desired shape (FIGS. 2B and 2C). Finally, unnecessary parts are removed and the molded object 110 and the base 130 are separated as necessary.

[About the porous part]
According to the direct modeling method capable of obtaining a three-dimensional model having a precise and complicated shape, the modeled object 110 having various porous structures can be formed by inputting appropriate (three-dimensional) modeling data. it can. By firing the shaped article 110 according to the manufacturing method of the present invention, a porous portion is formed and a ceramic article having the porous portion can be obtained. In the present invention, the porous portion means a portion having a plurality of open pores having a porosity of 5 vol (volume)% or more, a thickness of the bridge portion of 1 mm or less, and a pore diameter of 50 μm or more and 1000 μm or less. On the other hand, the dense portion in the present invention means a portion having a porosity of less than 5 vol (volume)% and a bridge portion having a thickness of 1 mm or more. Here, the porosity refers to the ratio of open pores to the volume of the ceramic article, and does not include closed pores. An open pore is a hole in which a part of the pore is connected to the outside (also called an open pore). Closed pores are pores that are not connected to the outside. Further, the communication hole refers to a hole whose both ends are connected to the outside, and is included in the open pores. The porosity can be measured by the mercury injection method. Further, the bridge portion refers to a structural portion that forms a hole in the porous portion, and the thickness of the bridge portion refers to the shortest distance between the hole and the hole adjacent thereto.

FIG. 3 shows an enlarged schematic view of a part of the surface of the porous ceramics 301, which is a ceramics article having a porous portion according to the present invention, in which the cross-sectional shape of the holes can be seen. Here, the cross-sectional shape means the shape of a surface perpendicular to the extending direction of the hole. FIG. 3 shows an example, and the present invention is not limited to these. Although FIG. 3 shows a hole having a circular cross-sectional shape, the hole may have a circular cross-sectional shape of any of a circle, a quadrangle, and a triangle, and holes having a plurality of shapes may be provided in combination.

In the present invention, the porosity is the open porosity measured by the mercury injection method as described above. In the case of the porous ceramics 301 having the openings 302 as shown in FIG. 3, the porosity is the ratio of the volume of the openings 302 to the total volume including the pores of the porous ceramics 301. The porous portion has a plurality of openings each having a pore diameter of 50 μm or more and 1000 μm or less. In the present invention, the hole diameter 303 refers to an elliptical (including circular) minor axis diameter (2b) that approximates the contour of the hole. The method for approximating the contour of the hole to an elliptical shape is as follows. First, the maximum distance (2a) between the contours in the contour of the hole and the area S in the contour of the hole are measured. The minor axis radius b of the approximate ellipse can be calculated by b=S/(πa). As described above, the major axis diameter 2a and the minor axis diameter 2b are introduced. The pore diameter can be measured using an optical microscope, a scanning electron microscope (SEM), or the like in an arbitrary cross section that is substantially perpendicular to the openings of the ceramic article.

The opening period 304, shape, pore diameter 303, porosity, etc. of the porous part can be controlled independently by changing the input molding data. In addition, when the irradiation energy density by the energy beam is reduced, it is possible to form a porous portion having a random shape.

The average pore diameter is the average value of the pore diameters 303 of a plurality of pores in the porous part. In the calculation of the average pore diameter, the open pores and the closed pores may be regarded as having substantially the same diameter, and the open pores and the closed pores may be measured and calculated without distinction. In the present invention, the average pore diameter of the pores of the porous portion is preferably 50 μm or more and 1000 μm or less. The open pores and the closed pores cannot be distinguished only by observing an arbitrary cross section of the ceramic article with an optical microscope or SEM. Slice and view observation with SEM while cutting with a focused ion beam (FIB) or X-ray computed tomography (X-ray CT) can be used to check whether the target hole is an open pore or a closed pore. The communication hole can also be observed by the same method.

Here, the hole diameter 303, the opening period 304, and the porosity of the openings 302 of the porous ceramics 301 shown in FIG. 3 will be described. Consider the case where the openings 302 are circular and the openings 304 have equal intervals. When the opening period is 1, when the porosity (vol%) is 5, 10, 20, 30, 40, 50, 60, the pore diameters are 0.25, 0.36, 0.51 and 0.62, respectively. , 0.71, 0.80, 0.87, and the bridge portion thicknesses are 0.75, 0.64, 0.50, 0.38, 0.29, 0.20, and 0.13, respectively.

The pore size 303 of the porous part of the present invention may be constant in the direction in which the pores are stretched, or may change midway. Further, one hole may be divided into a plurality of holes on the way. A plurality of openings having different cross-sectional shapes may be combined. In any case, in order to complete the porous portion, it is necessary to remove the unsolidified powder remaining in the pores after the shaping is completed. Therefore, both ends of the hole communicate with the outside.

In the method for producing a three-dimensional object of the above-described direct modeling method, the accuracy in modeling is about several tens of μm, so if the hole diameter of the holes formed in the porous portion is 50 μm or less, the uniform hole diameter is Since 303 cannot be obtained and the opening 302 is filled up on the contrary, the porosity may decrease. Further, when the average pore diameter is larger than 1000 μm, the porous portion does not function as fine pores capable of controlling the flow of gas or liquid, so that it is preferably 1000 μm or less. Therefore, it is preferable that the average diameter of the openings 302 is 50 μm or more and 1000 μm or less. When the porous portion is formed for the purpose of reducing the weight, the preferable pore diameter is not limited to this as long as the desired mechanical strength can be obtained.

[Effect of liquid containing zirconium component]
In the case of the direct molding method such as the powder bed direct molding method or the cladding method described above, the ceramic powder melted by the energy beam irradiation is cooled by the surroundings and solidified to form a molded object. Since the ceramic has a large difference between the melting temperature and the solidifying temperature, thermal stress is generated, and many microcracks are generated in the molded article. Microcracks are distributed over the entire surface (inside and inside) of the modeled object. When the cross section of the modeled object is confirmed by a scanning electron microscope or the like, most of the microcracks have a width of several nm to several μm. Moreover, the length of the microcracks varies from several μm to several mm.

According to the present invention, the microcracks can be reduced and the mechanical strength of the molded article can be improved by absorbing and heating the liquid containing the zirconium component in the microcracks of the ceramic shaped article having a porous structure.

By observing the cross section of the shaped article obtained by heating after absorbing the zirconium-containing liquid, it was confirmed that crystals of zirconium composition were formed throughout, and the mechanical strength of the resulting ceramic article was improved. This is because the aluminum oxide and the zirconium component that form the shaped article form a eutectic relationship, so that microcracks are easily reduced in the heating step, and recrystallization proceeds and the bonding force between the crystal structures is strong. Therefore, it is considered that the mechanical strength of the ceramic article is improved. It is absorbed from the pores of the model and adheres to the surface of the porous structure and microcracks of the model. It is speculated that the zirconium component adhered to the porous surface was solid-phase diffused over a wide area within the crystal forming the shaped article by heating, and the crystal was recrystallized with the composition containing the zirconium component. It is considered that such a structure enhances the bonding force between the crystal structures of the resulting ceramic article and improves the mechanical strength.

Therefore, the present invention is characterized in that the zirconium component is introduced into the shaped article formed by melting and solidifying the powder with the energy beam. Even if the powder contains a zirconium component in advance, it is not possible to suppress the occurrence of cracks during modeling, so the bond strength between crystal structures is not sufficient, and the effect of the present invention (improvement of mechanical strength ) Cannot be obtained.

[Absorbing effect of liquid containing zirconium component in porous part]
The difference in the absorption effect of the zirconium component-containing liquid between the porous part and the dense part will be described. Here, in the present invention, the porous part and the dense part have different porosities, and the porosity of the porous part is 5% by volume or more, and the porosity of the dense part is less than 5% by volume. is there. When the porosity of the porous portion is 5% by volume or more, it is possible to obtain the functions required as a porous material such as heat resistance, light weight, and use as a flow channel. Further, by having a porosity of 5% by volume or more, the zirconium component spreads inside the porous portion of the shaped article, and sufficient strength can be obtained. The porosity of the porous portion is preferably 5% by volume or more and 60% by volume or less. When the porosity of the porous portion is 60% by volume or less, sufficient strength as a ceramic article can be obtained, which is preferable. The closed pores included in the porous portion do not contribute much to the function improvement of the porous portion. Further, it does not have a function of spreading the zirconium component inside the shaped article. Therefore, from the viewpoint of obtaining sufficient strength, the proportion of closed pores contained in the porous portion is preferably 1% by volume or less. More preferably, it is 0.5% by volume or less.

　It is necessary to absorb a sufficient amount of zirconium component in the modeled object in order to repair the microcracks generated during modeling. In the ceramic shaped article having the porous portion, the zirconium component-containing liquid permeates into the shaped article through the openings. In addition, since the surface area is large, a large amount of zirconium component penetrates as compared with the dense portion. Further, since the bridge portion forming the holes in the porous portion is fine and thin, the zirconium concentration has a great influence on the forming accuracy and the mechanical strength. That is, if the amount of zirconium component to be absorbed in the porous portion is not controlled, enlargement of the tissue containing the zirconium component may occur in the subsequent heating step, which may lead to deterioration in modeling accuracy, and the dense portion In comparison, it is more difficult for the porous portion having a fine structure to satisfy both the molding accuracy and the mechanical strength than the dense portion. Therefore, in the present invention, the modeling accuracy and the mechanical strength have a correlation with the Zr content rate, and it has been found that setting the Zr content rate to an appropriate value is preferable in terms of achieving both the modeling accuracy and the mechanical strength.

First, regarding the mechanical strength, if the Zr content is low, the degree of improvement in mechanical strength is small, and the possibility that the porous part will be damaged during processing or in the operating environment increases. In the present invention, when the ratio of the zirconium component in the metal component forming the metal oxide in the porous portion is 0.3 mol% or more, the mechanical strength practically usable as a ceramic article can be obtained.

Next, describe the modeling accuracy. If the content of the zirconium component added to the aluminum oxide as the main component becomes excessive, the melting point of the porous part lowers, so that a portion where the crystal melts occurs when the shaped article in which zirconium is absorbed is heated. As a result, in particular, in the porous body, the fine bridge portion is easily deformed and the modeling accuracy is lost, the opening is blocked, and the porous body does not function as a porous body. Therefore, from the viewpoint of modeling accuracy, it is necessary to control the Zr content in the porous portion more finely than in the dense portion. In the present invention, by setting the ratio of the zirconium component in the metal component forming the metal oxide in the porous portion to 2.0 mol% or less, the shape of the bridge portion can be maintained and sufficient modeling accuracy can be obtained.

From the above, in the present invention, in the porous portion, in order to simultaneously realize modeling accuracy and mechanical strength, the ratio of the zirconium component in the metal component constituting the metal oxide in the porous portion is 0.3 mol% or more.2. It should be 0 mol% or less. Further, the ratio of the zirconium component in the metal component forming the metal oxide in the porous portion is preferably 0.3 mol% or more and 1.5 mol% or less.

Furthermore, under this condition, it is preferable that the zirconium component becomes a metal oxide compounded with another metal component to form a zirconia region having an average circle equivalent diameter of 5 μm or more on the surface or inside of the bridge part. As the other metal component, for example, a gadolinium component is preferable, the gadolinium component is preferably the same mol or more as the zirconium component, and the zirconia region is preferably a composite metal oxide of zirconium and gadolinium. By taking such a form, high mechanical strength of the zirconium component is effectively imparted to the bridge portion and contributes to improvement of mechanical strength of the entire porous portion.

The method for producing a ceramic article according to the present invention is characterized by having the following four steps (i) to (iv).
(I) A powder of a metal oxide containing aluminum oxide as a main component is leveled to form a powder layer.
(Ii) The powder layer is irradiated with an energy beam based on modeling data to melt, solidify, or sinter the powder.
(Iii) A liquid containing a zirconium component is absorbed in a shaped article having a porous portion, which is formed by repeating the above step (i) and the above step (ii).
(Iv) The above-mentioned shaped object that has absorbed the liquid containing the above-mentioned zirconium component is heated.

The liquid is absorbed in the absorption step so that the ratio of the zirconium component in the metal component contained in the porous part is 0.3 mol% or more and 2.0 mol% or less. At this time, the ratio of the zirconium component in the metal component contained in the porous portion is preferably 0.3 mol% or more and 1.5 mol% or less.

<Step (i)>
The method for producing a shaped article according to the present invention includes a step (i) of forming a powder layer by leveling a powder of a metal oxide containing aluminum oxide as a main component.

Aluminum oxide is a general-purpose structural ceramic, and by appropriately sintering or melting and solidifying it, a shaped article with high mechanical strength can be obtained.

The metal oxide powder according to the present invention preferably has a zirconium oxide content of less than 0.1 mol %. Further, the ratio of the zirconium component in the metal component contained in the powder of the metal oxide is preferably less than 0.15 mol%. In a modeled object having a porous structure that absorbs a zirconium-containing liquid, there is a large difference in the zirconium concentration between the crystal part of the modeled object and the microcrack part of the modeled object, so only the microcrack vicinity is selected. Can be melted. As a result, it is possible to suppress the deformation of the modeled object due to the heating process.

The powder in the present invention more preferably contains at least one selected from gadolinium oxide, terbium oxide and praseodymium oxide as an accessory component. Since the powder contains gadolinium oxide, it has a lower melting point than aluminum oxide alone in the vicinity of the Al ₂ O ₃ —Gd ₂ O ₃ eutectic composition. As a result, the powder can be melted with a small amount of heat, and the diffusion of energy in the powder is suppressed, so that the modeling accuracy is improved. Further, by including gadolinium oxide, the shaped article has a phase separation structure composed of two or more phases. This suppresses the extension of cracks and improves the mechanical strength of the modeled object. Even when gadolinium oxide is replaced with an oxide of another rare earth element (except terbium and praseodymium), the same effect as gadolinium oxide can be obtained. When the energy beam is a laser beam, because the powder has sufficient energy absorption, the spread of heat in the powder is suppressed and becomes local, and the influence of heat on the non-printing part is reduced, so that the shaping accuracy is reduced. Is improved. For example, when an Nd:YAG laser is used, terbium oxide (Tb ₄ O ₇ ) or praseodymium oxide (Pr ₆ O ₁₁ ) exhibits good energy absorption, and thus may be contained in the powder as an accessory component. More preferable.

Since the eutectic composition ratio of the rare earth oxide material consisting of gadolinium oxide, terbium oxide and praseodymium oxide, which is an accessory component, and aluminum oxide is 46:54 (mol %), the composition ratio of the rare earth oxide material and aluminum oxide is Is preferably within the range of ±5 mol% from the above eutectic composition ratio, that is, 41:59 to 51:49 (mol %). Within this range, it is possible to obtain the effect of lowering the melting point by using ceramics having a eutectic composition.

From the above viewpoints, more preferable powders include Al ₂ O ₃ —Gd ₂ O ₃ , Al ₂ O ₃ —Tb ₄ O ₇ , Al ₂ O ₃ —Gd ₂ O ₃ —Tb ₄ O ₇ , and Al ₂ O. _3- Pr ₆ O ₁₁ , Al ₂ O ₃ -Gd ₂ O ₃ -Pr ₆ O ₁₁ , Al ₂ O ₃ -Gd ₂ O ₃ -Tb ₄ O ₇ -Pr ₆ O _{11 and the} like can be mentioned.

The base material used in the present invention may be appropriately selected and used from materials such as ceramics, metal, and glass that are usually used in the production of three-dimensional shaped objects, in consideration of the use and manufacturing conditions of the shaped object. it can. In the step (iv), when heating the shaped article integrated with the base, it is preferable to use heat-resistant ceramics for the base.

The method of arranging the powder on the base is not particularly limited. In the case of the powder bed fusion bonding method, as shown in FIGS. 1A to 1H, the powders are arranged in layers on the base with rollers, blades, or the like. In the case of the cladding method, as shown in FIG. 2A to FIG. 2C, the powder is jetted and supplied from the nozzle to the irradiation position of the energy beam, and the powder is overlaid on the base or the shaped object arranged on the base. At the same time as arranging the powder in a shape, the powder is melted and solidified by irradiation with an energy beam to produce a shaped article.

<Step (ii)>
The method for producing a shaped article according to the present invention includes a step (ii) of irradiating the powder layer formed in the step (i) with an energy beam based on shaping data to melt, solidify, or sinter the powder. .. Hereinafter, this step will be described based on a preferred embodiment.

In the case of the powder bed fusion bonding method, as shown in FIGS. 1A to 1H, a predetermined region on the surface of the powder placed on the base in step (i) is irradiated with an energy beam to melt the powder and then solidify. Let In the case of the cladding method, as shown in FIGS. 2A to 2C, in the step (i), the powder is jet-supplied and the powder is placed on the base so as to be built up, and at the same time, The whole is irradiated with an energy beam to melt and solidify the powder. When the powder is irradiated with an energy beam, the powder absorbs energy, the energy is converted into heat, and the powder is melted. When the irradiation of the energy beam is completed, the melted powder is cooled and solidified by the atmosphere and the adjacent peripheral portion thereof, and a shaped object is formed. Due to the rapid cooling during the melting and solidifying process, stress is generated in the surface layer and inside of the shaped article, and innumerable microcracks are formed. The shaped object may be formed by irradiating the powder layer with an energy beam and sintering it.

As the energy beam to be used, a light source having an appropriate wavelength is selected in view of the absorption characteristics of the powder. In order to perform highly accurate modeling, it is preferable to employ a laser beam or electron beam having a narrow beam diameter and high directivity. Examples of general-purpose laser beams include a YAG laser in the 1 μm wavelength band, a fiber laser, and a CO ₂ laser in the 10 μm wavelength band. When the powder contains terbium oxide or praseodymium oxide as an accessory component, a YAG laser having a wavelength band of 1 μm is suitable.

<Process (iii)>
The method for producing a molded article according to the present invention comprises a step of absorbing a liquid containing a zirconium component (sometimes referred to as a zirconium component-containing liquid) in a molded article formed by repeating the step (i) and the step (ii). Have.

On the shaped article obtained in step (ii), a new powder is placed in step (i). When the arranged powder is irradiated with the energy beam, the powder in the energy beam irradiation portion is melted and solidified to form a new modeled object integrated with the original modeled object. By alternately repeating step (i) and step (ii), a molded article having a desired three-dimensional shape can be obtained.

Then, a liquid containing a zirconium component (sometimes referred to as a zirconium component-containing liquid) is absorbed in the obtained shaped product.

Describing the zirconium component-containing liquid here, a zirconium component-containing liquid composed of a zirconium component raw material, an organic solvent, and a stabilizer is a preferable example.

Various zirconium compounds can be used as raw materials for the zirconium component. In the case of absorbing into a shaped article mainly composed of alumina, a raw material containing no metal element other than zirconium is preferable. As a raw material for the zirconium component, a metal alkoxide of zirconium or a salt compound such as chloride or nitrate can be used. Among them, the use of metal alkoxide is preferable because the liquid containing the zirconium component can be uniformly absorbed in the microcracks of the shaped article. Specific examples of the zirconium alkoxide include zirconium tetraethoxide, zirconium tetra n-propoxide, zirconium tetraisopropoxide, zirconium tetra n-butoxide, zirconium tetra t-butoxide and the like.

First, a zirconium alkoxide solution is prepared by dissolving zirconium alkoxide in an organic solvent. The amount of the organic solvent added to the zirconium alkoxide is preferably 5 or more and 30 or less in terms of molar ratio with respect to the compound. More preferably, it is 10 or more and 25 or less. In the present invention, that the addition amount of A is 5 with respect to B in a molar ratio means that the addition amount of A is 5 times that of B. If the concentration of zirconium alkoxide in the solution is too low, a sufficient amount of zirconium component cannot be absorbed by the shaped article. On the other hand, if the concentration of zirconium alkoxide in the solution is too high, the zirconium component in the solution aggregates, and the zirconium component cannot be uniformly arranged in the microcrack portion of the modeled object.

As the organic solvent, alcohol, carboxylic acid, aliphatic or alicyclic hydrocarbons, aromatic hydrocarbons, esters, ketones, ethers, or a mixed solvent of two or more thereof is used. Examples of alcohols include methanol, ethanol, 2-propanol, butanol, 2-methoxyethanol, 2-ethoxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-propoxy-2-propanol, 4-Methyl-2-pentanol, 2-ethylbutanol, 3-methoxy-3-methylbutanol, ethylene glycol, diethylene glycol, glycerin and the like are preferable. As the aliphatic or alicyclic hydrocarbons, n-hexane, n-octane, cyclohexane, cyclopentane, cyclooctane and the like are preferable. As the aromatic hydrocarbons, toluene, xylene, ethylbenzene and the like are preferable. Preferred esters are ethyl formate, ethyl acetate, n-butyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate and the like. As the ketones, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and the like are preferable. Examples of ethers include dimethoxyethane, tetrahydrofuran, dioxane, diisopropyl ether and the like. In preparing the zirconium component-containing liquid used in the present invention, it is preferable to use alcohols among the above-mentioned various solvents from the viewpoint of stability of the solution.

Next, the stabilizer will be explained. Since zirconium alkoxide has high reactivity with water, it is rapidly hydrolyzed by the addition of water in the air or water to cause cloudiness or precipitation of the solution. In order to prevent these, it is preferable to add a stabilizer to stabilize the solution. Examples of the stabilizer include β-diketone compounds such as acetylacetone, 3-methyl-2,4-pentanedione, 3-ethyl-2,4-pentanedione and trifluoroacetylacetone; methyl acetoacetate and ethyl acetoacetate. , Butyl acetoacetate, allyl acetoacetate, benzyl acetoacetate, isopropyl acetoacetate, tert-butyl acetoacetate, isobutyl acetoacetate, ethyl 3-oxohexanoate, ethyl 2-methylacetoacetate, ethyl 2-fluoroacetoacetate, acetoacetate 2 Β-ketoester compounds such as methoxyethyl; and alkanolamines such as monoethanolamine, diethanolamine and triethanolamine. The addition amount of the stabilizer is preferably 0.1 or more and 3 or less in molar ratio with respect to the zirconium alkoxide. More preferably, it is 0.5 or more and 2 or less.

Another preferred example is a zirconium component-containing liquid composed of zirconium component particles, a dispersant, and a solvent.

As the zirconium component particles, zirconium particles or zirconia particles that are oxides can be used. Zirconium particles or zirconia particles may be prepared by crushing each material by the top-down method, or by a bottom-up method from metal salts, hydrates, hydroxides, carbonates, etc., such as hydrothermal reaction. Or a commercially available product may be used. The size of the particles is 300 nm or less, more preferably 50 nm or less in order to penetrate into the microcracks.

The shape of the fine particles is not particularly limited, and may be spherical, granular, columnar, elliptic spherical, cubical, rectangular parallelepiped, needle-shaped, columnar, plate-shaped, scale-shaped, or pyramid-shaped.

The dispersant preferably contains at least one of an organic acid, a silane coupling agent, and a surfactant. Examples of the organic acid include acrylic acid, 2-hydroxyethyl acrylate, 2-acryloxyethyl succinic acid, 2-acryloxyethyl hexahydrophthalic acid, 2-acryloxyethyl phthalic acid, 2-methylhexanoic acid, 2- Ethylhexanoic acid, 3-methylhexanoic acid, 3-ethylhexanoic acid and the like are preferable. Preferred examples of the silane coupling agent include 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, hexyltrimethoxysilane, octyltriethoxysilane, and decyltrimethoxysilane. Examples of the surfactant include ionic surfactants such as sodium oleate, potassium fatty acid, sodium alkyl phosphate, alkylmethyl ammonium chloride, and alkylaminocarboxylate, polyoxyethylene laurin fatty acid ester, polyoxyethylene alkylphenyl. Nonionic surfactants such as ether are preferred.

As the solvent, alcohols, ketones, esters, ethers, ester-modified ethers, hydrocarbons, halogenated hydrocarbons, amides, water, oils, or a mixed solvent of two or more thereof is used. Preferred alcohols are, for example, methanol, ethanol, 2-propanol, isopropanol, 1-butanol, ethylene glycol and the like. As the ketones, for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and the like are preferable. Preferred esters are, for example, ethyl acetate, propyl acetate, butyl acetate, 4-butyrolactone, propylene glycol monomethyl ether acetate, methyl 3-methoxypropionate and the like. Preferred ethers are, for example, ethylene glycol monomethyl ether, diethylene glycol monobutyl ether, butyl carbitol, 2-ethoxyethanol, 1-methoxy-2-propanol, 2-butoxyethanol and the like. As the modified ethers, for example, propylene glycol monomethyl ether acetate is preferable. As the hydrocarbons, for example, benzene, toluene, xylene, ethylbenzene, trimethylbenzene, hexane, cyclohexane, methylcyclohexane and the like are preferable. Preferred halogenated hydrocarbons are, for example, dichloromethane, dichloroethane and chloroform. Preferred amides are, for example, dimethylformamide, N,N-dimethylacetamide and N-methylpyrrolidone. As the oils, for example, mineral oil, vegetable oil, wax oil and silicone oil are preferable.

The zirconium component-containing liquid may be prepared by simultaneously mixing zirconium particles or zirconia particles with a dispersant and a solvent, or may be mixed with zirconium particles or zirconia particles and a dispersant and then mixed with a solvent. .. Alternatively, the zirconium or zirconia fine particles may be mixed with the solvent and then the dispersant may be mixed, or the dispersant and the solvent may be mixed and then the zirconium or zirconia fine particles may be mixed. You may. The solution may be prepared by reacting at room temperature or refluxing.

The solid concentration of the zirconia component is determined by the above molar ratio of zirconium alkoxide, organic solvent, and stabilizer. The weight percentage of the zirconia solids is preferably in the range of 3% to 20%, more preferably 8% to 15%. If the concentration is low, it becomes difficult to obtain the effect of filling the microcracks. If the weight% is 3% or more, a certain effect is obtained, and if it is 8% or more, the effect is further enhanced. When the weight% is high, the viscosity becomes too high, and the liquid is difficult to be absorbed even in the microcracks, and it becomes difficult to obtain the effect. When the weight% is 20% or less, a certain effect is obtained. If it is 15% or less, the effect is further enhanced.

The powder melted by the energy beam irradiation in the above step (ii) is cooled by the surroundings and solidifies to form an intermediate shaped object. In the case of ceramics, since the difference in melting/solidifying temperature is large, many microcracks occur in the intermediate shaped product.

By this step (iii), the zirconium component-containing liquid penetrates not only on the surface layer of the modeled object but also along the microcracks to be distributed inside the modeled object. The method for absorbing the zirconium component-containing liquid in the shaped product is not particularly limited as long as a sufficient amount of the zirconia component can be present in a sufficient range of the microcracks of the shaped product. The shaped product may be impregnated in the zirconium component-containing liquid, the zirconium component-containing liquid may be atomized and sprayed onto the intermediate shaped product, or may be applied with a brush or the like. Further, a plurality of these methods may be combined, or the same method may be repeated a plurality of times. When the zirconium component-containing liquid is sprayed and when the zirconium component-containing liquid is applied, 5% by volume or more and 20% by volume or less of the zirconium component-containing liquid of the shaped article not absorbing the zirconium component-containing liquid is sprayed or applied. Preferably. If it is less than 5% by volume, the amount of zirconium component arranged in the microcrack portion of the molded article may be insufficient, and the microcrack portion may not melt. When it is more than 20% by volume, when the step (i) is carried out after the present step (iii), it may be difficult to uniformly dispose the powder on the shaped article due to the influence of the zirconium component-containing liquid. In the case of a molded article having a large volume that can be obtained by repeating steps (i) and (ii) to form a molded article having a porous portion, the molded article is immersed in a zirconium component-containing liquid and degassed under reduced pressure. The method of impregnating and then impregnating is preferable. Alternatively, while the steps (i) and (ii) are repeated to form a shaped article having a porous portion, it is preferable that the zirconium component-containing liquid be sprayed in a mist state to be absorbed by the shaped article at each stage.

<Process (iv)>
In step (iv) of the method for producing a shaped article according to the present invention, the shaped article having the zirconium component-containing liquid absorbed therein is heated.

In the above step (iii), the zirconium component-containing liquid is distributed in the surface layer of the shaped article and the microcracks inside the shaped article.

As described above, since the zirconium component has a relationship of forming a eutectic with aluminum oxide, melting starts at the eutectic point in the portion where these components are present. For example, the eutectic point of aluminum oxide and zirconium oxide is about 1900° C., which is lower than the melting point of each component alone (Al ₂ O ₃ is 2070° C. and ZrO ₂ is 2715° C.). That is, melting starts at a temperature lower than the melting temperature of the modeled product containing aluminum oxide as the main component. That is, the melting point at the location where zirconium is present can be greatly reduced locally, and by utilizing this difference in melting point, heating is performed at a temperature equal to or higher than the eutectic point and lower than the melting point of the shaped article, and only the vicinity of the microcracks is heated. It can be selectively locally melted. Specifically, the shaped article that has undergone the step (iv) is heated so that the maximum temperature becomes 1600° C. or higher and 1710° C. or lower.

When the temperature of the microcracks reaches the maximum temperature of 1600°C to 1710°C, the microcracks containing the zirconium component melt. Therefore, the heating time does not matter. In the molten state, the diffusion of atoms proceeds in the direction in which the surface energy decreases, and eventually microcracks decrease or disappear. By controlling the heating temperature, only the vicinity of the portion where the zirconium component is present can be melted, so that the shape of the modeled object is not destroyed and the advantage of the direct modeling method is secured. Therefore, the shape of the modeled object is maintained even if it is heated for a long time. The mechanical strength of the molded article solidified and recrystallized after melting is greatly improved by the reduction and disappearance of microcracks.

If a sufficient amount of zirconia component is present in the microcracks, the vicinity of the microcracks is melted as described above, and the microcracks are reduced or eliminated. In particular, when the vicinity of the microcracks approaches the eutectic composition in which zirconium oxide is in the vicinity of 22 mol% with respect to the molded product containing aluminum oxide as the main component in an amount of 78 mol%, the vicinity of the microcracks is more easily melted. In order to reduce or eliminate the microcracks by melting the vicinity of the microcracks, it is preferable to heat at a temperature of 1650° C. or higher and 1710° C. or lower. More preferably, it is 1662°C to 1670°C.

The method of heating the shaped object is not particularly limited. The shaped article that has absorbed the zirconium component-containing liquid may be heated again by irradiating it with an energy beam, or may be placed in an electric furnace and heated. In the case of heating with the energy beam, it is necessary to grasp the relationship between the input heat amount of the energy beam and the temperature of the model with a thermocouple or the like in advance so that the model is heated to the above preferable temperature.

During the heating process, the molded product may stick to the setter (firing shelf, shelf board, floor board, etc.) due to melting near the surface layer and microcracks. Therefore, when the shaped object is placed on the setter in the heating step, the setter is preferably inert. As the inert setter, for example, platinum or the like can be applied in the air atmosphere, and iridium or the like can be applied in the low oxygen atmosphere.

<Flow of each process>
Hereinafter, the order of each process and an example of a repeated pattern will be described.

The basic flow is basically a flow of executing each step in the order of step (i) → step (ii) → step (iii) → step (iv), but step (iii) and step (iv) are repeated. You may execute.

By repeatedly performing the step (iii) and the step (iv), the eutectic composition in which the vicinity of the microcracks of the modeled object is about 22 mol% of zirconium oxide with respect to 78 mol% of the modeled object containing aluminum oxide as the main component It is preferable to bring them closer. This facilitates melting in the vicinity of the microcracks and improves the effect of reducing and eliminating the microcracks. At this time, the liquid is absorbed in the absorbing step such that the ratio of the zirconium component to the metal component contained in the porous portion is 0.3 mol% or more and 2.0 mol% or less.

[Composite ceramic parts consisting of porous and dense parts]
FIG. 7 shows a schematic view of an example of a piece of composite ceramic component 403 including a porous portion 401 and a dense portion 402 for holding the porous portion 401. In FIG. 7, the porous portion 401 is surrounded by the dense portion 402 and integrated. These composite ceramic parts 403 can be used as a suction plate by connecting intake and exhaust members. The example of FIG. 7 is merely an example, and a plurality of porous parts 401 may be independently arranged in the dense part 402, or the dense part 402 is arranged inside the porous part 401. Good.

In the present invention, the dense part 402 constituting the composite ceramic part 403 is made of a metal oxide containing aluminum and zirconium, and the ratio of the zirconium component in the metal component constituting the metal oxide is the porous part. It is smaller than 401.

The following will describe the method for producing a shaped article according to the present invention in detail with reference to Examples, but the present invention is not limited to the following Examples.

(Example 1)
In this example, a porous portion having a grid pattern was produced. This roughly corresponds to the case where the lattice pattern has a hole period of 175 μm.

<Step (i), Step (ii) and Step (iii)>
α-Al ₂ O ₃ powder, Gd ₂ O ₃ powder and Tb ₂ O _3.5 powder (Tb ₄ O ₇ powder) were prepared, and the molar ratio was Al ₂ O ₃ :Gd ₂ O ₃ :Tb ₂ O _3. Each powder was weighed so that ₅ =77.4:20.8:1.8. The respective weighing powders were mixed by a dry ball mill for 30 minutes to obtain a mixed powder (material powder).
When the composition of the material powder was analyzed by ICP emission spectroscopy, the content of zirconium oxide was less than 0.1 mol %.

Next, the molded article of Example 1 was formed through steps basically similar to the steps shown in FIGS. 1A to 1H described above.
A ProX DMP 100 (trade name) manufactured by 3D SYSTEMS Co., which is equipped with a 50 W Nd:YAG laser (beam diameter: 65 μm) was used for forming the modeled object.

First, a 20 μm-thick first powder layer of the above material powder was formed on a pure alumina base using a roller (step (i)). Then, the powder layer was irradiated with a 30 W laser beam to melt and solidify the material powder in a square region of 10 mm×10 mm in a mesh shape. The drawing speed was 180 mm/s and the drawing pitch was 175 μm (step (ii)). The drawing line was inclined at 45 degrees with respect to each side of the square. Next, a 20 μm-thick powder layer was newly formed with a roller so as to cover the melting/solidifying portion (step (i)). The powder layer directly above the square region was irradiated with a laser in a state of being orthogonal to the drawing line of the first layer, and the powder in the region of 10 mm×10 mm was melted and solidified (step (ii)).

By such a repeating step (iii), a modeled object having a bottom surface of 10 mm×10 mm and a height of 3 mm was formed. The obtained shaped product contained unsolidified powder, and the unsolidified powder was removed to obtain a shaped product having a porous structure.

<Process (iv)>
The zirconium component-containing liquid was prepared as follows. A solution was prepared by dissolving 85% by weight of zirconium (IV) butoxide (hereinafter referred to as Zr(On-Bu) ₄ ) in 1-butanol. The above Zr(On-Bu) ₄ solution was dissolved in 2-propanol (IPA), and ethyl acetoacetate (EAcAc) was added as a stabilizer. The molar ratio of each component was Zr(O-n-Bu) ₄ :IPA:EAcAc=1:15:2. Then, the zirconium component-containing liquid was prepared by stirring at room temperature for about 3 hours. The weight concentration of the zirconia solid content of this liquid is 8%.

The above-described shaped product processed for the test was immersed in the zirconium component-containing liquid, degassed under reduced pressure for 1 minute to permeate (impregnate) the liquid into the inside of the shaped product, and then naturally dried for 1 hour.

The shaped article impregnated (absorbed) with the zirconium component-containing liquid as described above was provided with a platinum wire on an alumina plate, placed on the platinum wire, and placed in an electric furnace for heating. Specifically, the temperature was raised to 1670° C. in 2.5 hours in the air atmosphere, kept at 1670° C. for 50 minutes, then turned off, and cooled to 200° C. or less in 1.5 hours (step (iv)). ).

In Example 1, the step of absorbing the zirconium component-containing liquid (step (iii)) and the step of heating (step (iv)) were alternately repeated 5 times to obtain a ceramic article having a porous portion. It was

<Evaluation>
[Evaluation methods]
The average pore size was evaluated by the following method. A scanning electron microscope (SEM) is used to acquire an SEM image of the polished surface of the shaped article provided with the porous portion. The average pore size is calculated as follows. First, for each hole, the area S and the maximum distance (2a) between the contours of the holes are obtained from the SEM image, and b=S/(πa) is calculated. The average value of the minor axis diameters of the ellipse having the major axis diameter 2a and the minor axis diameter 2b thus obtained is defined as the average pore diameter. The average pore size described in this specification is synonymous with this.

Also, the porosity was measured by the mercury injection method. Therefore, the porosity in the present invention refers to the ratio of open pores to the volume of the ceramic article, and does not include closed pores.

The Zr content and the average particle size in the Zr region were evaluated by the following methods. By SEM-EDX analysis, composition analysis of the porous portion was performed in an area of 2 mm×2 mm, and the ratio of Zr component in all metal elements was defined as Zr content. For the average particle size, the composition distribution of the porous part is mapped in the same area, the continuous area containing the Zr component as the main component is regarded as one zirconia area, and the area is calculated. The diameter (equivalent circle diameter) was calculated. The equivalent circle diameter was calculated for a plurality of zirconia regions, and the average value was used as the average equivalent circle diameter of the zirconia regions.

Molding accuracy and mechanical strength were evaluated by the following methods. The modeling accuracy refers to the difference between the dimension and the design dimension of the ceramic article that has undergone the firing process after modeling. In a modeled object having a height of 10 mm×10 mm and a height of 3 mm, the maximum change rates on the upper surfaces of the modeled objects in step (iii) and step (iv) are compared, and A, B, and C are in descending order of the rate of change. write. That is, if the rate of change is 3% or less, the modeling accuracy A is 3% and 5% or less is the modeling accuracy B, and if the variation rate is 5% or more, the modeling accuracy C is generated. Those that do not exist are referred to as modeling accuracy D. Specifically, the molding accuracy A has an upper surface dent of 0.3 mm or less, and the molding accuracy B has an upper surface dent of more than 0.3 and is 0.5 mm or less. In the case of accuracy C, the dent on the upper surface was larger than 0.5 mm.

Mechanical strength was measured as follows. First, a SEM image of a sample surface which was polished by impregnating and burning the porous part (step (iv)), and then using No. 250 to No. 15000 abrasive paper, and finally using No. 15000 lapping film abrasive paper I got 1. Subsequently, the sample from which the SEM image 1 was acquired was placed on a No. 600 diamond polishing machine (manufactured by Musashino Electronics Co., Ltd.) rotating at 80 rpm, cut by applying a load of 0.5 kg, and the SEM image 2 Got Mechanical strength A is that the defect ratio of SEM image 2 to SEM image 1 is 10% or less, mechanical strength B is 10% or more and 20% or less, mechanical strength C is 20% or more, Was written.

[Evaluation results]
An optical microscope image of the porous portion of the produced ceramic article is shown in FIG. 4A. An SEM image is shown in FIG. 5A, and a mapping image of the composition distribution of the Zr component by SEM-EDX in the same region is shown in FIG. 5B. The obtained porous portion had pores communicating from one surface to the opposite surface. The average pore diameter in the porous portion was 115 μm, and the porosity was 31% by volume. The closed pores were 0.4% by volume. The Zr content was 1.56 mol %. The average equivalent circle diameter of the zirconia region was 20 μm, and the zirconia region was distributed so as to extend from the bridge portion to the outside of the bridge portion. In the porous part of the obtained ceramic article, the forming accuracy was B and the mechanical strength was A.

(Example 2)
The present example is an example in which the content of the zirconium component in the porous portion is different.
A porous ceramic was produced under the same conditions as in Example 1 except that the step of immersing in the zirconium component-containing liquid (step (iii)) and the step of heating (step (iv)) were alternately repeated twice each. The produced porous ceramics article was evaluated in the same manner as in Example 1.

(Example 3)
The present example is an example in which the arrangement of the openings in the porous portion is random.
A porous ceramic article was produced under the same conditions as in Example 1 except that the drawing speed was 220 mm/s and the drawing pitch was 125 μm in order to obtain a porous portion having randomly arranged openings. An optical microscope image of the porous portion is shown in FIG. 4B. The produced porous ceramics were evaluated in the same manner as in Example 1.

(Example 4)
The present example is an example of producing a composite ceramic component including a porous portion made of ceramics and a dense portion made of ceramics for holding the porous portion. In FIG. 7, this corresponds to the case where the porous portion has a lattice-like pattern with a period of 175 μm and the dense portion surrounds and is integrated.

The porous part was produced under the same laser irradiation conditions as in Example 1. The dense portion was irradiated with a laser beam of 30 W, the drawing speed was 100 mm/s to 140 mm/s, and the drawing pitch was 100 μm. The SEM image of the boundary between the porous part and the dense part of the obtained composite ceramic part is shown in FIG. 6A. 6B and 6C show mapping images of the composition distribution of the Zr component by SEM-EDX in the regions corresponding to the part 601 of the porous part and the part 602 of the dense part shown in FIG. 6A, respectively. The porous part and the dense part of the produced ceramic article were evaluated in the same manner as in Example 1.

(Examples 5 to 8)
The present example is an example in which the content of the zirconium component in the lattice-shaped porous portion is different. The conditions are the same as in Example 1 except that the step of immersing in the zirconium component-containing liquid was repeated 3, 4, 6, and 8 times, respectively.

(Examples 9 to 14)
The present example is an example in which the content of the zirconium component in the porous portion having random openings is different. The conditions are the same as in Example 3 except that the step of immersing in the zirconium component-containing liquid is repeated 2, 3, 4, 6, 7, and 8 times, respectively.

(Examples 15 and 16)
The present example is an example in which the content of the zirconium component in the composite ceramic component including the porous portion made of ceramics and the dense portion made of ceramics for holding the porous portion is different. The conditions are the same as in Example 4 except that the step of immersing in the zirconium component-containing liquid is repeated 4 and 6 times, respectively.

(Comparative Examples 1 to 3)
Comparative Example 1 does not include the step of immersing the intermediate shaped article in the zirconium component-containing liquid (step (iii)) and the step of heating the intermediate shaped article absorbed with the zirconium component-containing liquid (step (iv)). However, a porous ceramic was obtained in the same manner as in Example 1 except for the steps of Comparative Example 2 once and Comparative Example 3 8 times. The produced ceramic article having a porous portion was evaluated in the same manner as in Example 1.

(Comparative example 4)
This comparative example is an example in which the content of the zirconium component in the porous portion having random openings is different. The conditions are the same as in Example 3 except that the step of immersing in the zirconium component-containing liquid was performed once.

(Examples 17 to 19)
The present example is an example in which the content of the zirconium component in the composite ceramic component including the porous portion and the dense portion for holding the porous portion is different. The conditions are the same as in Example 4 except that the step of immersing in the zirconium component-containing liquid is repeated 2, 3, and 7 times, respectively.

(Comparative example 5)
This comparative example is an example in which the content of the zirconium component in the composite ceramic component including the porous portion and the dense portion for holding the porous portion is different. The conditions are the same as in Example 4 except that the step of immersing in the zirconium component-containing liquid was repeated 9 times.

Table 1 collectively shows the above evaluation results of the examples and the comparative examples.

(Discussion)
[About Zr content and Zr component]
Comparing Example 1, Example 2, and Comparative Examples 1 to 3, the Zr content was increased as the number of Zr impregnations (0 times, 1, 2, 5, 8 times) in the porous ceramics part increased. The rate has increased. It was found that as the Zr content increased, the average grain size in the Zr region also increased, and the precipitated crystal grains having an average grain size of 10 μm or more were combined to form a continuous network. It was found by SEM-EDX and XRD that most of the Zr components did not form zirconium oxide (ZrO ₂ ) but formed a complex oxide with Gd.

Further, as is clear from the results of Example 4 in Table 1 and FIGS. 6B and 6C, when the Zr content is Zr-impregnated under the same conditions, the porous part is more dense than the dense part. Became higher. This is because in the porous portion, the zirconium component-containing liquid permeates through the pores to the inside of the shaped article, and since the surface area is large, a large amount of the zirconium component permeates into the dense portion. it is conceivable that.

[Relationship between Zr concentration, modeling accuracy, and mechanical strength]
The ceramic articles having modeling accuracy of A, B, and C had no damage and were practically usable as ceramic articles. In particular, the ceramic articles having modeling accuracy of A and B have good modeling accuracy and were suitable as an example for obtaining a ceramic article having a complicated shape or a fine shape. On the other hand, the comparative ceramic article having a molding accuracy of D had a poor molding accuracy, a large difference from the design dimension, and damage such as cracks was observed, so that a practical specification could not be obtained.

Comparison of Examples 1 to 3, Examples 5 to 14 and Comparative Examples 1 to 4 in which a ceramic article having only a porous portion is formed, and the relationship between the zirconium content in the porous portion and the forming accuracy will be considered. The modeling accuracy is good when Zr is not contained or when the Zr content is 1.5 mol% or less (0≦Zr≦1.5 mol%), and the size and design of the ceramic article that has undergone the firing step after modeling The rate of change from the dimension was 3% or less (modeling accuracy A). When the Zr content increased, the modeling accuracy decreased, and when the Zr content was in the range of 1.5<Zr≦2.0 mol%, the change rate was more than 3% and 5% or less (modeling accuracy B). When the Zr content further increased and the Zr content became larger than 2.0 mol%, the change ratio became larger than 5% (modeling accuracy C). As the Zr content increases, the melting point lowers, so that the crystal melts more and the bridge in the porous portion deforms, resulting in loss of modeling accuracy. As a result, the porosity and the average pore diameter also change from the designed values.

On the other hand, the mechanical strength will improve as the Zr content increases. When the Zr content is less than 0.3 mol% (0≦Zr<0.3 mol%), the mechanical strength is weak and the defect ratio is more than 20% (mechanical strength C). When the Zr content increased (0.3≦Zr<0.7 mol %), the defect ratio decreased (more than 10% and 20% or less), and sufficient mechanical strength was obtained (mechanical strength B). When the Zr content further increased and the Zr content was 0.7 mol% or more, the defect ratio was 10% or less and the mechanical strength was further improved (mechanical strength A). When the degree of improvement in mechanical strength was small, the percentage of the porous portion missing during processing or in the environment of use increased.

From the above, in the porous portion, in order to simultaneously realize the modeling accuracy and the mechanical strength (both the modeling accuracy and the mechanical strength are A or B), the ratio of the zirconium component in the metal component forming the metal oxide is 0. It was found that it is necessary to be 3 mol% or more and 2.0 mol% or less. Further, it was found that the zirconium component under this condition forms a crystal grain having an average particle size of 10 μm or more as a metal oxide compounded with another metal component, and the crystal grains are connected to each other to have a network structure. The crystal grains containing zirconium as a main component form a crystal complexed with Gd and form a network that permeates intricately inside the eutectic structure. This effectively imparts to the eutectic structure the high mechanical strength originally possessed by the crystal grains containing zirconium as the main component, so that sufficient mechanical strength can be achieved even in the porous part composed of fine bridge parts. Will be obtained. In order to achieve more preferable modeling accuracy and mechanical strength at the same time (both modeling accuracy and mechanical strength are A), the ratio of the zirconium component in the metal component forming the metal oxide is 0.7 mol% or more and 1.5 mol% or less. I found it necessary to be.

As described above, by the method for manufacturing a porous ceramics shaped article according to the present invention, it is possible to greatly improve the mechanical strength of the shaped article while obtaining high modeling accuracy.

According to the present invention, it is possible to further improve the mechanical strength of a ceramic article having a porous portion while directly utilizing the features of the direct modeling method capable of obtaining a molded article having a precise and complicated shape.

The present invention is not limited to the above embodiments, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are attached to open the scope of the present invention.

The present application claims priority based on Japanese Patent Application No. 2018-229383 filed on December 6, 2018 and Japanese Patent Application No. 2019-219949 filed on December 4, 2019. , The entire contents of which are incorporated herein.

101... Powder 102... Powder layer 103... Solidification part 110... Model 130... Base 151... Stage 152... Roller 180... Energy beam source 181... Scanner 190... Liquid injection nozzle 201... Cladding nozzle 202... Powder supply hole 203 ... Energy beam 301 ... Porous ceramics 302 ... Opening 303 ... Hole diameter 304 ... Opening period 401 ... Porous portion 402 ... Dense portion 403 ... Composite ceramic part

Claims (22)

1. A method of manufacturing a ceramic article, comprising:
   (I) a step of leveling a powder of a metal oxide containing aluminum oxide as a main component to form a powder layer,
   (Ii) irradiating the powder layer with an energy beam based on modeling data to melt and solidify or sinter the powder;
   (Iii) a step of absorbing a liquid containing a zirconium component in a shaped article having a porous portion, which is formed by repeating the step (i) and the step (ii),
   (Iv) heating the shaped article that has absorbed a liquid containing the zirconium component,
   In the absorbing step, the liquid is absorbed so that the ratio of the zirconium component in the metal component contained in the porous portion is 0.3 mol% or more and 2.0 mol% or less.
2. A method of manufacturing a ceramic article, comprising:
   (I) A step of irradiating a powder of a metal oxide containing aluminum oxide as a main component with an energy beam based on molding data to melt and solidify or sinter the powder to form a molded article having a porous portion. When,
   (Ii) a step of absorbing a liquid containing a zirconium component in the shaped article formed in the step (i),
   (Iii) heating the shaped article that has absorbed the liquid containing the zirconium component,
   In the absorbing step, the liquid is absorbed so that the ratio of the zirconium component in the metal component contained in the porous portion is 0.3 mol% or more and 2.0 mol% or less.
3. The method for producing a ceramic article according to claim 1 or 2, wherein the ratio of the zirconium component in the metal components contained in the metal oxide powder is less than 0.15 mol%.
4. The method for producing a ceramic article according to any one of claims 1 to 3, wherein the powder of the metal oxide contains a rare earth oxide.
5. The method for producing a ceramic article according to claim 4, wherein the rare earth oxide further contains at least one selected from gadolinium oxide, terbium oxide and praseodymium oxide.
6. A ceramic article comprising a metal oxide containing aluminum oxide as a main component and having a porous portion,
   A ceramic article, wherein the ratio of the zirconium component in the metal component contained in the porous portion is 0.3 mol% or more and 2.0 mol% or less.
7. The ceramic article according to claim 6, wherein the ratio of the zirconium component in the metal component contained in the porous portion is 0.3 mol% or more and 1.5 mol% or less.
8. At least a part of the zirconium component contained in the porous portion forms a zirconia region as a metal oxide compounded with another metal component forming the porous portion, and the average particle diameter of the zirconia region is 10 μm or more. The ceramic article according to claim 6 or 7, which is
9. The ceramic article according to claim 8, wherein the porous portion contains a gadolinium component in the same mol or more as the zirconium component, and the zirconia region is made of a metal oxide in which zirconium and gadolinium are compounded.
10. The ceramic article according to any one of claims 6 to 9, wherein the pores contained in the porous portion have an average pore diameter of 50 µm or more and 1000 µm or less.
11. The ceramic article according to any one of claims 6 to 10, wherein the porosity of the porous portion is 5% by volume or more and 60% by volume or less.
12. The ceramic article according to any one of claims 6 to 11, wherein a ratio of closed pores contained in the porous portion is 0.5% by volume or less.
13. A ceramic article comprising a metal oxide containing aluminum oxide as a main component, the ceramic article having a dense part and a porous part,
    A ceramic article, wherein the ratio of the zirconium component in the metal component contained in the porous portion is higher than the ratio of the zirconium component in the metal component contained in the dense portion.
14. The ceramic article according to claim 13, wherein the ratio of the zirconium component in the metal component contained in the porous portion is 0.3 mol% or more and 2.0 mol% or less.
15. At least a part of the zirconium component contained in the porous portion forms a zirconia region as a metal oxide compounded with another metal component forming the porous portion, and the average particle diameter of the zirconia region is 10 μm or more. 15. The ceramic article according to claim 13 or 14.
16. The ceramic article according to claim 15, wherein the porous portion contains a gadolinium component in the same mol or more as the zirconium component, and the zirconia region is made of a metal oxide in which zirconium and gadolinium are compounded.
17. The ceramic article according to any one of claims 13 to 16, wherein the porous portion has a hole communicating with the outside.
18. The ceramic article according to claim 17, wherein the average pore size of the openings is 50 μm or more and 1000 μm or less.
19. The ceramic article according to claim 15 or 16, wherein the porosity of the porous portion is 5% by volume or more and 60% by volume or less.
20. The ceramic article according to any one of claims 13 to 19, wherein a ratio of closed pores contained in the porous portion is 0.5% by volume or less.
21. The ceramic article according to any one of claims 13 to 20, wherein the dense portion is provided so as to hold the porous portion.
22. The ceramic article according to any one of claims 13 to 21, which is an adsorption plate having the porous portion as an intake/exhaust portion.

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