Zirconia sintered compact and method for manufacturing the same

Abstract

To provide a zirconia sintered compact that supports a metal material without having any problems of the conventional technology described above, and to provide a method for manufacturing such a zirconia sintered compact.SOLUTION: A zirconia sintered compact 10 of the present disclosure comprises zirconia crystal particles 1 having nanopores 2 on a surface thereof, and a metal material 3 is supported in the nanopores 2. A method according to the present disclosure for manufacturing a zirconia sintered compact 10 includes: providing a zirconia sintered compact having zirconia crystal particles with the nanopores on a surface thereof; and irradiating the zirconia with an ultra-short pulse laser under conditions where a metal-containing solution is present on the surface of the zirconia sintered compact.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present disclosure relates to a zirconia sintered body and a method for manufacturing the same.

Background Art

[0002] Conventionally, as a means for improving the hydrophilicity of a base material used in a water-containing atmosphere, research has been conducted on forming a fine structure on the surface of the base material. As an example of these base materials, a zirconia sintered body having high mechanical strength can be mentioned. It is known that a zirconia sintered body can be directly bonded to bone by osseointegration by forming a fine structure on the surface to improve hydrophilicity. In order to be applied as a biomaterial such as an artificial joint or a dental implant, research has been conducted on forming a fine structure on the surface of the zirconia sintered body.

[0003] Examples of the processing method for forming a fine structure on the zirconia sintered body include a mechanical processing method such as sandblasting or a chemical processing method such as an etching treatment.

[0004] For example, Patent Document 1 discloses that in a dental implant using zirconia as a base material, a fine structure is formed on at least a part of the outer surface of the anchor portion by a processing method such as polishing blast, sandblast, or etching treatment.

[0005] However, the processing method of Patent Document 1 has concerns such as a phase transition from the tetragonal phase to the monoclinic phase of zirconia and the adhesion of contaminants generated due to the direct contact of the zirconia sintered body with a machine or the like.

[0006] It is known that a zirconia sintered body undergoes a phase transition due to the influence of stress, heat, etc. Due to the volume change accompanying the phase transition, there has been a problem that defects such as cracks and fractures occur on the surface and inside of the sintered body, resulting in a decrease in mechanical strength. For this reason, there has been a demand for a processing method of a zirconia sintered body that can suppress the phase transition to the monoclinic phase by processing.

[0007] Therefore, in order to provide a zirconia sintered body with less phase transition to the monoclinic phase and excellent hydrophilicity, a zirconia sintered body provided with zirconia crystal particles having nano-pores on the surface has been proposed by irradiating the surface of the sintered body with an ultra-short pulse laser under specific conditions (see Patent Document 2).

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] By the way, in order to add various functions such as antibacterial properties to industrial materials and products, attempts have been made to introduce functional metal materials onto the surfaces of the base materials of these industrial materials and products.

[0010] Regarding the zirconia sintered body, it is considered that the zirconia sintered body can be applied to various uses by supporting a metal material on its surface.

[0011] However, when a metal material is attached to a zirconia sintered body by applying and baking a glaze containing a metal raw material such as silver, the attachment film is supported on the entire surface of the zirconia sintered body. Then, it becomes difficult for zirconia to be exposed on the surface, and there arises a problem that it becomes difficult to obtain the effect of zirconia being exposed on the surface, for example, the osseointegration effect. Furthermore, in this case, since the attachment film is supported on the entire surface of the zirconia sintered body, there arises a problem that the dimensions (thickness) of the base material (substrate) change. When the dimensions of the base material increase, it becomes difficult to use it as a small component, and it is necessary to perform a design considering the dimensional change. In addition, by applying heat for baking, a phase transition from tetragonal to monoclinic phase also occurs in the zirconia sintered body, so the mechanical strength as a member decreases.

[0012] On the other hand, even if a metal material is introduced by using a plating method in which a zirconia sintered body is immersed in a plating solution containing metal ions and an electric current is passed through the plating solution to deposit a metal on the surface of the zirconia sintered body, since the attachment film is supported on the entire surface of the zirconia sintered body, the above problems occur. Also, in this case as well, the base material is damaged and a phase transition from tetragonal to monoclinic phase occurs in the zirconia sintered body.

[0013] Therefore, the present disclosure provides a zirconia sintered body that supports a metal material and does not have the problems of the prior art as described above, and a method for manufacturing such a zirconia sintered body.

Means for Solving the Problems

[0014] The present inventors have studied a zirconia sintered body and a method for manufacturing the same.

[0015] That is, the present invention is as described in the claims, and the gist of the present disclosure is as follows. <Aspect 1> A zirconia sintered body having zirconia crystal particles having nano pores on the surface and a metal material supported in the nano pores. <Aspect 2> The zirconia sintered body according to Embodiment 1, wherein the monoclinic phase ratio of the surface is 5% or less. <Aspect 3> The zirconia sintered body according to Embodiment 1 or 2, wherein the ratio of nano pores carrying the metal material is 30% or more. <Aspect 4> The zirconia sintered body according to any one of Embodiments 1 to 3, wherein the metal material contains a metal element selected from the group consisting of Ag, Cu, and Fe. <Aspect 5> The zirconia sintered body according to any one of Embodiments 1 to 4, wherein the average diameter of the nano pores is 10 nm or more and 400 nm or less. <Aspect 6> The zirconia sintered body according to any one of Embodiments 1 to 5, wherein the average depth of the nano pores is 50 nm or more and 800 nm or less. <Aspect 7> Providing a zirconia sintered body having zirconia crystal particles with nano pores on the surface, and Irradiating the zirconia sintered body with an ultrashort pulse laser in a state where a metal-containing solution exists on the surface of the zirconia sintered body The method for producing a zirconia sintered body according to any one of Embodiments 1 to 6, comprising: <Aspect 8> The method according to Aspect 6, wherein the ultrashort pulse laser is an ultrashort pulse laser having a pulse width of 1000 fs or less. <Aspect 9> The method according to Aspect 6 or 7, wherein the ultrashort pulse laser is an ultrashort pulse laser having a laser output of 60 mW or more and 150 mW or less, and the laser scanning speed is 10 mm / s or more and 500 mm / s or less.

Advantages of the Invention

[0016] According to the present disclosure, there are provided a zirconia sintered body that supports a metal material and does not have the problems of the prior art as described above, and a method for manufacturing such a zirconia sintered body.

Brief Description of the Drawings

[0017]

Figure 1A

Figure 1B

Figure 2A

Figure 2B

Figure 3A

Figure 3B

Figure 4

BEST MODE FOR CARRYING OUT THE INVENTION

[0018] Hereinafter, an example of an embodiment of the zirconia sintered body of the present disclosure will be described while showing an example of the embodiment.

[0019] 《Zirconia Sintered Body》 The zirconia sintered body of the present embodiment has zirconia crystal particles having nanopores on the surface, and a metal material is supported in the nanopores.

[0020] According to the zirconia sintered body of this embodiment, since the metal material is supported in the nano-pores on the surface, it is possible to suppress the problems caused by the prior art in which the adhesion film of the metal material is supported on the entire surface of the zirconia sintered body. That is, according to the zirconia sintered body of this embodiment, for example, (i) the metal is retained in the pores and is difficult to desorb, (ii) it becomes difficult for zirconia to be exposed on the surface, and the effects of zirconia being exposed on the surface, such as the osseointegration effect, can be easily obtained, and (iii) at least one of the dimensions (thickness) of the base material (substrate) being difficult to change can be achieved.

[0021] Further, preferably, the zirconia sintered body of this embodiment has a monoclinic phase ratio of 5% or less on the surface. This means that the phase transition to the monoclinic phase is suppressed on the surface of the zirconia sintered body. In the zirconia sintered body, a low monoclinic phase ratio, that is, a high tetragonal phase ratio, is preferable in terms of high strength.

[0022] The zirconia sintered body of this embodiment can be manufactured by preparing a zirconia sintered body having zirconia crystal particles with nano-pores on the surface and then supporting a metal in the pores. Therefore, when explaining the zirconia sintered body of this embodiment, in order to explain in detail for each aspect obtained in the production order, it is divided into the "zirconia sintered body having zirconia crystal particles with nano-pores on the surface" before supporting the metal and the "zirconia sintered body having the metal material supported in the nano-pores" after supporting the metal material on this zirconia sintered body, and will be described below. Regarding the "zirconia sintered body having zirconia crystal particles with nano-pores on the surface" before supporting the metal, the description in Patent Document 2 can also be referred to.

[0023] 〈Zirconia Sintered Body Having Zirconia Crystal Particles with Nano-Pores on the Surface〉 (Composition of Zirconia Sintered Body) In this embodiment, the "zirconia sintered body" is a sintered body having zirconia as a matrix (main phase), and zirconia (ZrO2 ) has the highest proportion of sintered body.

[0024] The zirconia sintered body according to this embodiment has a mass ratio of zirconia (ZrO 2 ) (when zirconia contains a stabilizing element, the total mass ratio of the stabilizing element and zirconia) is preferably 90% by mass or more and 100% by mass or less, 95% by mass or more and 100% by mass or less, 95% by mass or more and 99% by mass or less, or 99.5% by mass or more and 100% by mass or less.

[0025] The zirconia sintered body according to this embodiment preferably contains a stabilizing element. The stabilizing element is an element having a function of stabilizing zirconia. The stabilizing element is preferably at least one selected from the group consisting of yttrium (Y), scandium (Sc), calcium (Ca), magnesium (Mg), and cerium (Ce), more preferably at least one selected from the group of calcium, magnesium, and yttrium, and still more preferably yttrium.

[0026] The content of the stabilizing element (hereinafter, the content of the stabilizing element such as when the stabilizing element is yttrium is also referred to as "yttrium amount", etc.) is not particularly limited, but since a zirconia sintered body excellent in mechanical strength is easily obtained, it can be exemplified as 1 mol% or more and 6 mol% or less, 1 mol% or more and 5 mol% or less, or 2 mol% or more and 4 mol% or less. As the content of the stabilizing element that particularly increases the mechanical strength, 2.5 mol% or more and 3.5 mol% or less can be exemplified.

[0027] The zirconia sintered body according to this embodiment contains alumina (Al 2 O 3) may contain and may be composed of zirconia, a stabilizing element, and alumina. The alumina content can be exemplified as 0 mass% or more and 0.2 mass% or less, 0 mass% or more and 0.15 mass% or less, or 0 mass% or more and less than 0.1 mass%. Since the inclusion of a small amount of alumina facilitates sintering, the alumina content can be exemplified as more than 0 mass% and 0.2 mass% or less, 0.005 mass% or more and 0.15 mass% or less, 0.01 mass% or more and 0.12 mass% or less, 0.015 mass% or more and less than 0.1 mass%, or 0.02 mass% or more and 0.07 mass% or less.

[0028] Within the range where the effects of the zirconia sintered body according to this embodiment are not impaired, it may contain an element having a function of coloring zirconia (hereinafter, also referred to as a "coloring agent"). The coloring agent is an element having a function of coloring zirconia and may be an element having a function of suppressing the phase transition of zirconia. Specific examples of the coloring agent include at least one of transition metal elements and lanthanoid rare earth elements, preferably one or more selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), praseodymium (Pr), neodymium (Nd), europium (Eu), gadolinium (Gd), terbium (Tb), erbium (Er), and ytterbium (Yb), more preferably one or more selected from the group consisting of iron, cobalt, manganese, praseodymium, neodymium, terbium, and erbium, and even more preferably one or more selected from the group consisting of iron, cobalt, and erbium.

[0029] The zirconia sintered body according to this embodiment may contain inevitable impurities such as hafnia (HfO 2 ). The content of hafnia as an inevitable impurity varies greatly depending on the starting materials and their manufacturing methods, but for example, it may be 2.0 mass% or less. However, it is preferable not to contain elements that have a large impact on the effects of the zirconia sintered body according to this embodiment. For example, the zirconia sintered body according to this embodiment has a silicon content in terms of silica (SiO 2 ) of 0 mass ppm or more and 500 mass ppm or less, and titania (TiO 2)The converted titanium content satisfies at least one of 0 mass ppm or more and 500 mass ppm or less, and the silicon and titanium contents are preferably 0 mass ppm or more and 500 mass ppm or less, respectively. In this embodiment, when calculating values based on the composition such as the content and density, hafnia may be regarded as zirconia for calculation.

[0030] (Nanopores) As described above, the zirconia sintered body according to this embodiment has zirconia crystal particles having nanopores on the surface. The zirconia crystal particles having nanopores preferably have pores formed by irradiating the surface of the sintered body with an ultrashort pulse laser described later.

[0031] In this embodiment, "nanopores" refer to nanoporous-sized pores, that is, pores in which the distance between the two points with the largest distance on the outer periphery of the pores is less than 1 μm, and particularly refer to nanoporous-sized pores in a state formed by an ultrashort pulse laser. As a method for "confirming that zirconia crystal particles having nanopores are provided on the surface", for example, a method of observing the surface of the zirconia sintered body using an electron microscope such as SEM (Scanning Electron Microscope) or TEM (Transmission Electron Microscope) can be mentioned.

[0032] SEM images of the surface and cross-section of the zirconia sintered body having zirconia crystal particles having nanopores on the surface are shown in FIGS. 2A and 2B.

[0033] As shown in Fig. 2A, the zirconia crystal particles 1 on the surface of the zirconia sintered body 10 have nano-pores 2. Note that the zirconia sintered body 10 may have debris formed by re-solidification of molten zirconia crystal particles generated during laser processing at the openings of the nano-pores 2. As shown in Fig. 2B, only the zirconia crystal particles 1 on the surface of the zirconia sintered body 10 have nano-pores 2. That is, those having nano-pores 2 are limited to only the outermost surface of the zirconia sintered body 10, and nano-pores 2 are not formed in the zirconia crystal particles 1 deeper than the outermost surface. Note that the crystal particles on the outermost surface are crystal particles exposed on the surface of the zirconia sintered body and observable with an electron microscope. Therefore, the zirconia sintered body according to the present embodiment has an excellent hydrophilic surface, and the zirconia crystal particles 1 deeper than the outermost surface are not affected by laser processing when forming pores.

[0034] In the zirconia sintered body according to the present embodiment, the nano-pores of the zirconia crystal particles are open pores. This is different from closed pores (isolated pores) that exist isolated inside the crystal particles.

[0035] Therefore, if the above characteristics are recognized by observing the surface of the zirconia sintered body, the zirconia sintered body having nano-pores according to the present embodiment can be clearly distinguished from the conventional sintered body.

[0036] The average crystal grain size of the zirconia crystal particles is preferably 0.1 μm or more, more preferably 0.3 μm or more, and still more preferably 0.5 μm or more. On the other hand, the average crystal grain size of the zirconia crystal particles is preferably 10 μm or less, and more preferably 5.0 μm or less.

[0037] The average crystal grain size can be obtained by the planimetric method using an SEM image. That is, a circle with a known area is drawn on the SEM image, the number of crystal particles (Nc) inside the circle and the number of crystal particles (Ni) on the circumference of the circle are measured, and after making the total number of crystal particles (Nc + Ni) 250 ± 50, the average crystal grain size can be obtained using the following formula: Average crystal grain size = 2 / {π × (Nc + (1 / 2) × Ni) / (A / M 2 )} 0.5

[0038] In the above formula, Nc is the number of crystal grains inside the circle, Ni is the number of crystal grains on the circumference of the circle, A is the area of the circle, and M is the magnification of scanning electron microscope observation (for example, 5000 to 10000 times). If the number of crystal grains (Nc + Ni) in one SEM image is less than 200, (Nc + Ni) may be set to 250 ± 50 using a plurality of SEM images.

[0039] The average diameter of the nano-pores is preferably 10 nm or more and 400 nm or less, more preferably 20 nm or more and 200 nm or less, and still more preferably 50 nm or more and 180 nm or less. If the average diameter of the nano-pores is within the above range, a zirconia sintered body carrying a metal material in the pores can be easily obtained. The average diameter of the nano-pores can be measured using an electron microscope and image analysis software. For example, using the analysis software ImageJ (ver. 1.52), for the SEM image of the zirconia sintered body surface and the laser irradiation range, the region surrounded by the inner peripheral edge of the opening of the crystal grains is regarded as the nano-pores, and the maximum diameter thereof can be determined as the diameter of the nano-pores. By measuring all the nano-pores in the image and averaging those values, the average diameter can be calculated. The number of nano-pores to be measured is not particularly limited, but for example, it may be 200 or more and 1000 or less.

[0040] The average depth of the nano-pores is preferably 50 nm or more and 800 nm or less, more preferably 100 nm or more and 700 nm or less. If the average depth of the nano-pores is within the above range, a zirconia sintered body carrying a metal material in the pores can be easily obtained. The average depth of the nano-pores can be measured using an electron microscope and image analysis software. For example, using the analysis software ImageJ (ver. 1.52), for the SEM image of the cross-section of the sintered body (the cross-section perpendicular to the surface of the sintered body) in the laser irradiation range of the zirconia sintered body, from the position of the outermost surface side end of the opening of the crystal grains to the deepest part of the pores, by performing image analysis on the vertical distance, the depth of the nano-pores can be determined. By measuring this for all the nano-pores in the image and averaging their values, the average depth can be measured. The number of nano-pores to be measured is not particularly limited, but for example, it may be 3 or more and 20 or less.

[0041] In addition, in the zirconia sintered body according to this embodiment, grain boundary pores may or may not exist at the grain boundaries which are the boundaries between adjacent crystal grains. When grain boundary pores exist, the average diameter of the grain boundary pores is usually 0.01 μm or more and 0.3 μm or less. Since the nano-pores of the crystal grains in the zirconia sintered body according to this embodiment and the grain boundary pores existing at the grain boundaries are in different positions, they can be clearly distinguished from each other by electron microscope observation or the like.

[0042] 〈Zirconia Sintered Body with Metal Supported in Nano-Pores〉 In the zirconia sintered body of this embodiment, a metal material is supported in the nano-pores.

[0043] (Metal Material) There is no particular limitation on the metal material supported in the nano-pores, and it may be a metal element or a metal compound such as an oxide or a nitride. The metal material supported in the nano-pores is preferably a metal material containing a metal element selected from the group consisting of Ag, Cu, and Fe, and may be, for example, a metal element selected from the group consisting of Ag, Cu, and Fe, that is, Ag, Cu, and / or Fe in a metallic state.

[0044] (Metal loading in nanopores) SEM images of the surface and cross-section of a zirconia sintered body having metal in nanopores are shown in FIGS. 1A and 1B.

[0045] As shown in FIG. 1A, the zirconia crystal particles 1 on the surface of the zirconia sintered body 20 of the present embodiment have nanopores 2, and a metal material (for example, metal Ag in FIG. 1A) 3 is supported in the nanopores.

[0046] The ratio of nanopores supporting the metal material may be 20% or more and 90% or less, 25% or more and 80% or less, 30% or more and 70% or less, or 35% or more and 65% or less.

[0047] When the ratio of nanopores having a metal material among the nanopores formed on the surface of the zirconia sintered body is within the above range, the zirconia sintered body can sufficiently exhibit new functions associated with metal loading.

[0048] Here, the ratio of nanopores supporting the metal can be obtained as follows: · Prepare two SEM images. · Count the total number of nanopores and the number of nanopores with metal in the field of view of the SEM image, respectively. · Calculate the ratio (%) of nanopores supporting the metal using the following formula. Number of nanopores with metal / Total number of nanopores × 100 (%) · For each of the two SEM images, obtain the ratio of nanopores as described above for each image, and calculate the average value. Note that the definition of the nanopores to be counted is pores of "10 nm or more and 400 nm or less".

[0049] (Monoclinic phase ratio) The zirconia sintered body of the present embodiment in which a metal material is supported in nanopores may have a monoclinic phase ratio on the surface of 5% or less.

[0050] In the zirconia sintered body of the present embodiment, the monoclinic phase ratio on the surface is preferably 5% or less, more preferably 3% or less. The monoclinic phase ratio may be 0% or more, and examples thereof include more than 0% or 1% or more.

[0051] Here, the monoclinic phase ratio (hereinafter, also referred to as "M phase ratio") means that Raman spectroscopic measurement is performed on the zirconia sintered body, and 147 ± 5 cm -1 , 181 ± 5 cm -1 and 190 ± 5 cm -1 The peak intensity of the peak having a peak top at each is obtained, and the value calculated by the following formula 1 is meant.

[0052]

Equation

[0053] In the above formula, V m is the M phase ratio, It(147) is the peak intensity derived from the tetragonal phase of 147 ± 5 cm -1 , Im(181) is the peak intensity derived from the monoclinic phase of 181 ± 5 cm -1 , and Im(190) is the peak intensity derived from the monoclinic phase of 190 ± 5 cm -1 .

[0054] Raman spectroscopic analysis can be measured by a microscopic laser Raman spectrophotometer (for example, InVia Raman Microscope manufactured by Renishaw), and the peak intensity in each measurement region can be obtained using analysis software (for example, OriginPro manufactured by lightstone).

[0055] The M phase ratio of the zirconia sintered body of the present embodiment is preferably obtained by Raman spectroscopic measurement under the following conditions. Laser wavelength: 532 nm Laser beam diameter: 1 μm Measurement wavelength resolution: 0.4 cm -1 Exposure time: 2 to 3 seconds Number of integrations: 1 time Gratings: 1800 and 3000

[0056] 《Method for Manufacturing Zirconia Sintered Body》 The zirconia sintered body of the present embodiment can be manufactured by producing a zirconia sintered body having zirconia crystal particles with nano-pores on the surface and then supporting a metal in the pores.

[0057] Therefore, when explaining the method for manufacturing the zirconia sintered body of the present embodiment, it will be divided into the method for manufacturing the "zirconia sintered body having zirconia crystal particles with nano-pores on the surface" before supporting the metal and the method for manufacturing the "zirconia sintered body having a metal material supported in the nano-pores" after supporting the metal, and will be described below.

[0058] 〈Method for Manufacturing Zirconia Sintered Body Having Zirconia Crystal Particles with Nano-Pores on the Surface〉 The method for manufacturing the "zirconia sintered body having zirconia crystal particles with nano-pores on the surface" includes a step of irradiating the surface of the zirconia sintered body with an ultra-short pulse laser. By irradiating the surface of the zirconia sintered body with an ultra-short pulse laser, the above-described zirconia crystal particles having nano-pores can be formed. Regarding this method, reference can also be made to the description in Patent Document 2.

[0059] Although not all the mechanisms by which the nano-pores as described above are obtained by this method are clear, an example of the presumed mechanism of nano-pore formation will be described.

[0060] FIG. 4 is a schematic diagram for explaining the mechanism of nano-pore formation. As shown in FIG. 4, when an ultra-short pulse laser is irradiated onto the zirconia sintered body 10 under specific conditions, the laser light 11 is reflected at the grain boundaries of the zirconia crystal particles 1. As a result, a part of the zirconia crystal particles 1 on the surface of the zirconia sintered body absorbs the energy of the laser light 11 and is excited (FIG. 4(a)). In FIG. 4(a), reference numeral 12 represents the excited portion and reference numeral 13 represents the grain boundary reflection. Next, a high-density plasma 14 is generated by the interaction between the laser light and the bottom side of the zirconia crystal particles 1, and it becomes a high-energy state and voids 15 are formed (FIG. 4(b)). The formed voids absorb the laser light and further expand within the zirconia crystal particles (FIG. 4(c) and (d)). In FIG. 4(c), reference numeral 16 represents the laser light absorption, and in FIG. 4(d), reference numeral 17 represents the void expansion. Finally, it is presumed that the high-density plasma existing in the voids is discharged to the sintered body surface side of the zirconia crystal particles 1, thereby forming nano-pores 2 (FIG. 4(e) and (f)). In FIG. 4(e), reference numeral 18 represents the plasma discharge.

[0061] (Irradiation conditions of the ultra-short pulse laser) Irradiation with an ultrashort pulse laser can achieve surface processing that hardly involves a phase transition to the monoclinic phase of zirconia under specific conditions. The ultrashort pulse laser has a very short pulse width. Therefore, when laser irradiation is performed under specific irradiation conditions, the absorbed heat does not diffuse from the irradiated surface to the inside or the periphery of the surface, and only the irradiated portion can be non-thermally scattered (hereinafter also referred to as "ablation"). As a result, laser processing can be selectively performed on the surface of the zirconia sintered body. Furthermore, under specific conditions, since the influence of thermal energy extending to the periphery of the irradiated portion is small, the phase transition of zirconia to the monoclinic phase in the periphery of the irradiated portion occurs only in a narrow range compared to mechanical processing such as sandblasting. Thereby, the zirconia sintered body according to the present embodiment is less affected by the phase transition to the monoclinic phase due to processing and has high mechanical strength. In addition, since processing is performed on the zirconia sintered body in a non-contact manner, the influence of adhesion of contaminants through contact members is significantly suppressed. Furthermore, the ultrashort pulse laser is excellent in directivity and condensing property, and not only can selectively process only the irradiated portion, but also can process with a shallower grinding depth compared to mechanical processing. Therefore, unlike the mechanical processing method, no machining allowance is required for the zirconia dimensions.

[0062] The manufacturing method according to the present embodiment can perform processing in which nano-pores are formed only on the outermost surface of the sintered body and nano-pores are not formed in the zirconia crystal particles deeper than the outermost surface by setting various laser irradiation conditions such as the laser light source (wavelength), repetition frequency, pulse width of the laser, laser output, laser scanning speed, and number of laser scans. Since the zirconia crystal particles deeper than the outermost surface are not affected by the processing, a zirconia sintered body having nano-pores on the surface can be obtained without impairing the mechanical strength of the entire zirconia sintered body.

[0063] An example of suitable laser irradiation conditions in the manufacturing method according to the present embodiment will be described below.

[0064] The laser light source of the ultrashort pulse laser is preferably a titanium sapphire laser (wavelength: about 0.8 μm) or a laser of ytterbium (wavelength: about 1 μm). Also, a wavelength-variable femtosecond pulse light source by a parametric amplification device based on a non-linear wavelength conversion process may be used. The wavelength of the ultrashort pulse laser is not particularly limited. As the wavelength of the ultrashort pulse laser, for example, a wavelength within the range of the ultraviolet region to the near-infrared region may be used, and it can be appropriately selected from 200 nm or more and 2500 nm or less.

[0065] The laser output is preferably 200 mW or more and 800 mW or less, more preferably 500 mW or more and 750 mW or less, still more preferably 400 mW or more and 750 mW or less, and particularly preferably 450 mW or more and 700 mW or less.

[0066] Also, the pulse width of the laser is preferably 10 -15 seconds (1 femtosecond (fs)) or more and 10 -12 seconds (1 picosecond (ps), that is, 1000 femtoseconds (fs)) or less. If the laser output and the pulse width of the laser are within the above ranges, the energy density can be appropriately suppressed, and it becomes easier to ablate only the surface of the zirconia sintered body. As a result, it is easy to obtain nano-pores having a desired shape, and it is easy to obtain a zirconia sintered body having a low monoclinic phase ratio.

[0067] The repetition frequency is preferably 20 Hz or more and 300 kHz or less.

[0068] The number of laser scans is preferably 1 or more and 5 or less at the same position in order to form nano-pores having a suitable average depth. If the number of laser scans is 5 or less, it is easy to obtain a sintered body having a low monoclinic phase ratio.

[0069] The laser scanning speed is preferably 200 mm / s or more and 4000 mm / s or less, more preferably greater than 500 mm / s and 3000 mm / s or less, still more preferably 800 mm / s or more and 3000 mm / s or less, and particularly preferably 1000 mm / s or more and 2500 mm / s or less. If the scanning speed is within the above range, the processing accuracy and production efficiency are excellent.

[0070] The laser irradiation method may be a method in which continuous irradiation is performed at the same position and then movement is carried out, or a method in which continuous irradiation is performed at the same position with a slight movement relative to the irradiation beam diameter.

[0071] The zirconia sintered body irradiated with the ultrashort pulse laser is not particularly limited. For example, those having conventionally known physical properties such as particle diameter, density, composition, etc. can be used, and they can be manufactured by conventionally known methods.

[0072] For example, when the zirconia sintered body contains a stabilizing element, a manufacturing method including a molding step of molding a mixed powder containing a zirconia raw material and a stabilizing element raw material to obtain a molded body, and a sintering step of sintering the obtained molded body to obtain a sintered body, etc., can be used to manufacture a zirconia sintered body for laser irradiation.

[0073] In the molding step, a mixed powder containing a zirconia raw material and a stabilizing element raw material is provided. If the zirconia raw material and the stabilizing element are uniformly mixed, the manufacturing method of the mixed powder is arbitrary and may be either wet mixing or dry mixing. Since the uniformity of the obtained mixed powder is higher, the mixing method is preferably wet mixing, more preferably wet mixing by at least one of a wet ball mill and a wet stirring mill.

[0074] The zirconia raw material is zirconia or its precursor, and examples thereof include zirconia powder having a BET specific surface area of 4 m 2 / g or more and 20 m 2 / g or less.

[0075] The stabilizing element raw material is preferably a powder of a compound containing at least one selected from the group consisting of yttrium, scandium, calcium, magnesium, and cerium, and preferably includes a powder of a compound containing yttrium or its precursor. Further, in addition to or instead of the zirconia raw material and the stabilizing element raw material, a zirconia raw material in which the stabilizing element is dissolved, for example, yttrium-stabilized zirconia powder, may be used.

[0076] In the forming process, the mixed powder is formed to obtain a formed body. The forming method is arbitrary as long as a formed body with a desired shape is obtained. Examples of the forming method include at least one selected from the group consisting of press forming, injection molding, sheet forming, extrusion molding, and casting molding, and at least one of press forming and injection molding is preferable.

[0077] The shape of the formed body is arbitrary. In addition to the shape of a dental implant, shapes such as a disc shape, a columnar shape, and a polyhedral shape, and any shape according to the purpose and application, such as a dental orthodontic bracket, an artificial joint, a semiconductor manufacturing jig, and other complex shapes, can be exemplified.

[0078] The sintering method in the sintering process is arbitrary. Examples of the sintering method include at least one selected from the group consisting of atmospheric pressure sintering, pressure sintering, and vacuum sintering, and atmospheric pressure sintering and pressure sintering are preferable. The heating temperature in the sintering process is arbitrary.

[0079] <Method for manufacturing a zirconia sintered body in which a metal material is supported in nano pores> By irradiating the zirconia sintered body with an ultrashort pulse laser in a state where a metal-containing solution is present on the surface of the above-mentioned [zirconia sintered body having zirconia crystal particles with nano pores on the surface], a [zirconia sintered body in which a metal material is supported in nano pores] can be obtained.

[0080] More specifically, in a state where a metal-containing solution is present on the surface of a zirconia sintered body having nano pores on the surface, for example, in a state where a metal-containing solution is applied (coated, dropped, etc.) on the surface of a zirconia sintered body having nano pores on the surface, or in a state where a zirconia sintered body having nano pores on the surface is immersed in a metal-containing solution, when the zirconia sintered body is irradiated with an ultrashort pulse laser, a metal material can be supported in the nano pores.

[0081] According to this method, damage to the zirconia sintered body as the base material is eliminated or reduced, thereby suppressing the phase transition to the monoclinic phase. Therefore, it exhibits a low monoclinic phase ratio, and the metal material can be supported in the nano-pores without changing the dimensions of the base material. Specifically, according to this method, for example, the monoclinic phase ratio on the surface of the zirconia sintered body can be set to a low value of 5% or less.

[0082] In addition, the metal material supported in the nano-pores can be arbitrarily further treated by oxidation, nitridation, etc. to form metal compounds such as oxides and nitrides.

[0083] (Metal-containing solution) The metal-containing solution may be any solution containing a metal. The metal-containing solution may be a solution in which metal ions or metal complex ions are dissolved, or a solution (dispersion) containing fine metal particles. For example, it may be a nano-silver solution in which nano-sized silver fine particles are dispersed in a liquid in a high-concentration state.

[0084] (Irradiation conditions of the ultra-short pulse laser) As described above, an ultra-short pulse laser is used both when forming nano-pores and when supporting a metal material in the nano-pores, and the point of irradiating with the ultra-short pulse laser is the same.

[0085] However, there are also differences in the irradiation conditions between forming nano-pores and supporting a metal material in the nano-pores. To support the metal material in the pores, it is advisable to irradiate under the conditions shown below.

[0086] In addition, for irradiation conditions other than the laser output and the laser scanning speed, the irradiation conditions described in the column of (Irradiation conditions of the ultra-short pulse laser) of the above <Method for manufacturing a zirconia sintered body provided with zirconia crystal particles having nano-pores> can be followed.

[0087] The laser output is preferably 40 mW or more and 200 mW or less, or 40 mW or more and 300 mW or less, and more preferably 60 mW or more and 150 mW or less.

[0088] Also, the pulse width of the laser is preferably 10 -12 seconds (1000 fs = 1 ps) or less. Also, the pulse width of the laser is preferably 10 -15 seconds (1 fs) or more.

[0089] The laser scanning speed is preferably 10 mm / s or more and 500 mm / s or less, and more preferably 10 mm / s or more and 300 mm / s or less.

Examples

[0090] Hereinafter, the present disclosure will be specifically described by way of examples and comparative examples. However, the present disclosure is not limited to the examples.

[0091] (Measurement of average crystal grain size) The average crystal grain size of the zirconia sintered body was determined by the planimetric method using SEM images. As a measurement sample, a zirconia sintered body with a surface roughness of Ra ≦ 0.02 μm was used, which was treated in the air at a temperature 50 °C lower than the sintering temperature, and SEM observation was performed at a magnification (5000 - 10000 times).

[0092] A circle with a known area was drawn on the obtained SEM image, and the number of crystal grains (Nc) inside the circle and the number of crystal grains (Ni) on the circumference of the circle were measured. After making the total number of crystal grains (Nc + Ni) be 250 ± 50, the average crystal grain size was determined using the following formula. Here, A is the area of the circle, and M is the magnification of the scanning electron microscope observation. Average crystal grain size = 2 / {π × (Nc + (1 / 2) × Ni) / (A / M 2 )} 0.5

[0093] (Measurement of average diameter and average depth of nano - pores) The average diameter and average depth of the nano - pores were measured by image analysis using a scanning electron microscope (SEM) and image analysis software (ImageJ (ver. 1.52)).

[0094] The average diameter of the nano-pores was determined by image analysis. For the SEM image of the sintered body surface within the laser irradiation range, the region surrounded by the inner periphery of the openings of the crystal particles was defined as the nano-pores, and the maximum diameter thereof was defined as the diameter of the nano-pores. The average diameter of the nano-pores was calculated by measuring all the nano-pores in the image and averaging those values. The average depth of the nano-pores was measured by image analysis of the vertical distance from the position of the outermost surface side end of the opening of the crystal particles to the deepest part of the pores for the SEM image of the cross-section of the sintered body (a cross-section perpendicular to the sintered body surface) in the laser irradiation range of the sintered body. The average depth of the nano-pores was measured by measuring all the nano-pores in the image and averaging those values.

[0095] (Measurement of monoclinic phase ratio (M phase ratio)) The monoclinic phase ratio was determined by performing Raman spectroscopy measurement on the surface of the zirconia sintered body, obtaining the diffraction intensities of the (111) and (11-1) planes of the monoclinic phase, the (111) plane of the tetragonal phase, and the (111) plane of the cubic phase respectively, and referring to the value calculated by the following mathematical formula:

[0096] [Equation]

[0097] In the above formula, V m is the M phase ratio, It(147) is the peak intensity derived from the tetragonal phase at 147±5 cm -1 Im(181) is the peak intensity derived from the monoclinic phase at 181±5 cm -1 Im(190) is the peak intensity derived from the monoclinic phase at 190±5 cm -1 is the peak intensity derived from the monoclinic phase.

[0098] Raman spectroscopy analysis was performed using a microscopic laser Raman spectrophotometer (Renishaw InVia Raman Microscope). The peak intensity in each measurement region was obtained using analysis software (for example, OriginPro manufactured by Lightstone).

[0099] The conditions for Raman spectroscopy measurement are shown below. Laser wavelength: 532 nm Laser beam diameter: 1 μm Measuring wavelength resolution: 0.4 cm -1 Exposure time: 2 - 3 seconds Number of integrations: 1 time Gratings: 1800 and 3000

[0100] (Measurement of the ratio of nanopores carrying metal) The ratio of nanopores carrying metal was determined as follows: · Two SEM images were prepared. · The total number of all nanopores and the number of metal-carrying nanopores within the field of view of the SEM images were counted respectively. · The ratio (%) of nanopores carrying metal was determined using the following formula. Number of nanopores with metal / Total number of nanopores × 100 · For each of the two SEM images, the ratio of nanopores was determined as described above for each image, and the average value was calculated. Note that the definition of the nanopores to be counted was pores with a size of "10 nm or more and 400 nm or less".

[0101] 〈Example 1〉 As the raw material powder, 3 mol% yttrium-stabilized zirconia powder (trade name; TZ-3YS, manufactured by Tosoh Corporation, average crystal grain size 0.3 μm, surface area 7 m 2 / g) was used.

[0102] (Production of the primary sintered body) After the raw material powder was molded by a die press at a pressure of 50 MPa, it was further CIP molded at a pressure of 200 MPa using a cold isostatic pressing (hereinafter referred to as "CIP") apparatus to obtain a flat molded body with dimensions of 30 mm × 30 mm and a thickness of 5 mm.

[0103] The obtained flat molded body was placed in an alumina container and fired (primary sintering) to obtain a zirconia sintered body (primary sintered body).

[0104] The first sintering was carried out in the atmosphere. The temperature was raised from room temperature to 1500 °C at a heating rate of 100 °C / hour, held at the sintering temperature of 1500 °C for 2 hours, and then cooled to room temperature at a cooling rate of 100 °C / hour.

[0105] (Preparation of HIP-treated body) The zirconia sintered body (primary sintered body) obtained by sintering in the atmosphere was subjected to HIP treatment to obtain a HIP-treated body. The obtained HIP-treated body was used as the zirconia sintered body of this example.

[0106] The HIP treatment conditions were a temperature of 1350 °C, a HIP pressure of 150 MPa, and a holding time of 1 hour. Note that argon gas with a purity of 99.9% was used as the pressure medium, and the sample was treated using an alumina sealed container.

[0107] The obtained zirconia sintered body was irradiated with an ultrashort pulse laser under the laser irradiation conditions (pore formation) for surface processing shown in Table 1.

[0108] Next, a silver (Ag) nanoparticle dispersion (nanosilver dispersion NANOPURE PR-WB14R (Fujino Metals Co., Ltd.)) was prepared. Here, this silver nanoparticle dispersion was a dispersion in which nano-sized silver fine particles (particle diameter: about 10 nm, 1 mass%) were dispersed in water as a dispersion medium and contained polyvinylpyrrolidone (an amphiphilic polymer) as a dispersant.

[0109] The above Ag nanoparticle dispersion was dropped onto the surface of the sintered body with pores formed, and under the presence of this Ag nanoparticle dispersion, it was irradiated with an ultrashort pulse laser under the laser irradiation conditions shown in Table 2 to support Ag in the pores.

[0110] The ratio of nano-pores having Ag was measured. Also, the average diameter and average depth of the nano-pores, and the M-phase ratio of the surface were measured. The results are shown in Table 3.

[0111] 〈Examples 2 to 7〉 Zirconia sintered compacts of Examples 2 to 7 were produced in the same manner as in Example 1, except that the laser irradiation conditions for loading Ag into the pores were changed to the conditions shown in Table 2.

[0112] For the zirconia sintered compacts of Examples 2 to 7, the ratio of nano-pores having Ag, the average diameter and average depth of the nano-pores, and the M-phase ratio were measured. The results are shown in Table 3.

[0113] In addition, for the zirconia sintered compact of Example 4, SEM images of the surface of the zirconia sintered compact are shown in FIGS. 1A and 1B.

[0114] <Comparative Example 1> After producing a zirconia sintered compact having nano-pores in the same manner as in Example 1, the same evaluation as in Example 1 was performed on the zirconia sintered compact in which the step of loading Ag into the pores was not performed. The results are shown in Table 3.

[0115] In addition, for the zirconia sintered compact of Comparative Example 1, SEM images of the surface of the zirconia sintered compact are shown in FIGS. 2A and 2B.

[0116] <Comparative Example 2> After producing a zirconia sintered compact having nano-pores in the same manner as in Example 1, the same evaluation as in Example 1 was performed on the zirconia sintered compact in which a heating step was performed instead of laser irradiation to load Ag into the pores. The results are shown in Table 3.

[0117] The above heating step was performed as follows: Similar to Example 1, an Ag solution was dropped onto the surface of the sintered compact having pores formed therein, and the sintered compact was heated from room temperature to 450° C. at a heating rate of 200° C. / hour in an air atmosphere, held at the sintering temperature of 450° C. for 30 minutes, and then cooled to room temperature at a cooling rate of 200° C. / hour.

[0118] In addition, for the zirconia sintered compact of Comparative Example 2, SEM images of the surface of the zirconia sintered compact are shown in FIGS. 3A and 3B.

[0119] As shown in FIGS. 3A and 3B, when attempting to support Ag on the surface having nano-pores by heating instead of laser irradiation, since Ag and the organic matter are deposited on the surface, it was difficult to support only Ag.

[0120] <Comparative Example 3> In Example 1, without performing the ultra-short pulse laser irradiation for surface treatment (pore formation), on a laser-irradiation-processed-free as-sintered zirconia sintered body without nano-pores formed, laser irradiation for supporting Ag was performed under the conditions described in Table 2, and a zirconia sintered body of Comparative Example 3 was produced.

[0121] The same evaluation as in Example 1 was performed on the zirconia sintered body of Comparative Example 3. The results are shown in Table 3.

[0122] Note that the "-" in Table 3 of Comparative Example 3 indicates that it was not measured because nano-pores were not formed (the same applies to the "-" notation in Comparative Example 4).

[0123] <Comparative Example 4> In Example 1, as the ultra-short pulse laser irradiation conditions for surface treatment, on a zirconia sintered body that was micro-processed to form a triangular pyramid surface shape under the conditions described in Table 1, laser irradiation for supporting Ag was performed under the conditions described in Table 2, and a zirconia sintered body of Comparative Example 4 was produced.

[0124] The same evaluation as in Example 1 was performed on the zirconia sintered body of Comparative Example 4. The results are shown in Table 3.

[0125]

Table 1

[0126]

Table 2

[0127]

Table 3

[0128] From the results of the sintered body of the example, it was confirmed that in the zirconia sintered body of the present embodiment, metal elements are supported in the pores within the surface, and further, the monoclinic phase ratio of the surface is low and the phase transition to the monoclinic phase is suppressed.

Explanation of Signs

[0129] 1…Zirconia crystal particles 2…Nano pores 3…Metal material (Ag) 10…Zirconia sintered body 11…Laser light 12…Excitation part 13…Grain boundary reflection 14…High-density plasma 15…Void 16…Laser light absorption 17…Void expansion 18…Plasma discharge

Claims

1. A zirconia sintered body having zirconia crystal particles with nano-pores on its surface, and a metal material supported in the nano-pores.

2. The zirconia sintered body according to Claim 1, wherein the monoclinic phase ratio of the surface is 5% or less.

3. The zirconia sintered body according to Claim 1 or 2, wherein the ratio of the nano-pores supporting the metal material is 30% or more.

4. The zirconia sintered body according to Claim 1 or 2, wherein the metal material contains one or more metal elements selected from the group consisting of Ag, Cu, and Fe.

5. The zirconia sintered body according to Claim 1 or 2, wherein the average diameter of the nano-pores is 10 nm or more and 400 nm or less.

6. The zirconia sintered body according to Claim 1 or 2, wherein the average depth of the nano-pores is 50 nm or more and 800 nm or less.

7. Providing a zirconia sintered body having zirconia crystal particles with nano-pores on its surface, and irradiating the zirconia sintered body with an ultra-short pulse laser in a state where a metal-containing solution is present on the surface of the zirconia sintered body The method for producing a zirconia sintered body according to Claim 1, comprising:

8. The method according to Claim 7, wherein the ultra-short pulse laser is an ultra-short pulse laser having a pulse width of 1000 fs or less.

9. The method according to Claim 7 or 8, wherein the ultra-short pulse laser is an ultra-short pulse laser having a laser output of 60 mW or more and 150 mW or less, and the laser scanning speed is 10 mm / s or more and 500 mm / s or less.

Images