JP5399949B2 - Zirconia sintered body, zirconia composition and zirconia calcined body - Google Patents

Description

The present invention relates to a zirconia sintered body. The present invention also relates to a set formed product and the calcined body to obtain a zirconia sintered body.

Zirconium oxide (IV) (ZrO ₂ ) (hereinafter referred to as “zirconia”) has polymorphs, and zirconia causes a phase transition between the polymorphs. For example, tetragonal zirconia undergoes a phase transition to monoclinic crystals. For this reason, even if a sintered body is made of zirconia alone, the crystal structure is destroyed by this phase transition, so that the sintered body of zirconia alone has a drawback that sufficient strength as a product cannot be secured. Moreover, the sintered body of a zirconia single-piece | unit has the fault that the dimension of a sintered compact will change by the volume change by a phase transition.

  Therefore, stabilized zirconia or partially stabilized zirconia (PSZ; which suppresses the occurrence of phase transition by adding an oxide such as calcium oxide, magnesium oxide, yttrium oxide, or cerium oxide as a stabilizer to zirconia. Partially Stabilized Zirconia) is used. In particular, partially stabilized zirconia is a ceramic having excellent properties such as high strength and high toughness, and sintered parts of partially stabilized zirconia are used in various applications such as prosthetic materials and tools used for tooth treatment, for example. Is used.

  However, since partially stabilized zirconia is only partially stabilized, the problem of long-term stability has not been solved. For example, in the partially stabilized zirconia sintered body, when it is heated to about 200 ° C. in the presence of moisture, a phase transition from tetragonal to monoclinic crystal occurs. The strength deteriorates (hereinafter referred to as “low temperature deterioration”). Then, the manufacturing technology of the zirconia sintered compact which suppresses low temperature deterioration is developed (for example, refer patent document 1 and patent document 2).

  In the background arts related to Patent Document 1 and Patent Document 2, using a partially stabilized zirconia fine powder having an average particle size of 0.5 μm or less, the zirconia fine powder is sintered at 1200 ° C. to 1400 ° C., and zirconia firing is performed. Manufactures knots.

  Further, Patent Document 3 discloses a dental processing block for manufacturing a frame material having bending strength that is easy to cut and grind after complete sintering and can be applied to a bridge having a large number of teeth. Yes. The dental processing block described in Patent Document 3 is a complete sintered body of a metal oxide mainly composed of at least one of zirconia, alumina, mullite, and spinel. With respect to 100 parts by mass of the metal oxide, 1 to 23 parts by mass of lanthanum phosphate and / or aluminum phosphate is included as a crystal.

  In the method for producing a zirconia-based ceramic material described in Patent Document 4, 50 to 99 vol% of powder in which 1 to 30 vol% of zirconia partially stabilized with 2 to 5 mol% of yttria is replaced with unstabilized zirconia. Then, the mixed powder composed of alumina powder in the balance is molded and sintered. The zirconia-based ceramic material described in Patent Document 4 is composed of 95% or more of tetragonal crystals and 5% or less of monoclinic crystals when the average particle size of the zirconia matrix is less than 0.5 μm.

JP 2001-80962 A JP 2007-332026 A JP 2009-23850 A JP-A-2-255570

  The following analysis is given from the perspective of the present invention.

  When the zirconia sintered body is applied to, for example, a dental prosthetic material, it is desired that the fracture toughness value is higher. However, in the background art described in Patent Documents 1 to 3, the fracture toughness of the zirconia sintered body cannot be increased although the low temperature deterioration is suppressed and the bending strength is enhanced.

  The zirconia-based ceramic material described in Patent Document 4 contains monoclinic crystals before the accelerated low-temperature degradation test, and the phase transition to monoclinic crystals proceeds even under mild test conditions of 200 ° C. in the atmosphere. There is a problem with stability.

  On the other hand, in fully stabilized zirconia, although the phase transition to monoclinic crystal can be suppressed, the toughness and strength are lower than in partially stabilized zirconia.

  Further, in order to use the zirconia sintered body as a dental prosthetic material, in addition to strength, it is required to be colorless and translucent, but coloring may occur depending on the stabilizer. Or transparency may be lost.

An object of the present invention is to provide a zirconia sintered body having higher fracture toughness. Another object of the present invention is to provide a set formed product and the calcined body that Do a precursor of the zirconia sintered body.

According to the first aspect of the present invention, there is provided a zirconia sintered body having partially stabilized zirconia containing yttrium oxide as a stabilizer as a matrix phase. The standard deviation of the surface concentration of yttrium oxide when the concentration of yttrium oxide in each mass obtained by dividing a 10 μm × 10 μm region into a grid of 256 cells × 256 cells on the sample surface of the zirconia sintered body is expressed in mass%. Is 0.8 or more. However, those containing 5% to 50% crystallized glass on a volume basis, and those in which 10% or more of zirconia crystals exist as monoclinic crystals when heat-treated at 200 ° C. for 100 hours in the atmosphere. except for.

According to a preferred mode of the first aspect, the zirconia sintered body, containing phosphorus (P) element ^{4 × 10 -4 mol~4 × 10 -2} mol of the acid zirconium (IV) 1 mol.

  According to the preferable form of the first aspect, the phosphorus element content is 0.01% by mass to 1% by mass.

  According to a preferred form of the first aspect, the standard deviation is 2 or less.

  According to the preferable form of the first aspect, the zirconia sintered body further contains 0.2% by mass to 10% by mass of aluminum oxide.

  According to the preferable form of the first aspect, the zirconia sintered body further contains 0.03 mass% to 3 mass% of silicon dioxide.

According to the preferred form of the first aspect, the fracture toughness value of the zirconia sintered body measured according to JIS R1607 is 6 MPa · m ^1/2 or more.

  According to a preferred embodiment of the first aspect, when the zirconia sintered body is subjected to a low temperature deterioration accelerated test for 5 hours under the conditions of 180 ° C. and 1 MPa, X-rays on the surface of the zirconia sintered body after the low temperature deterioration accelerated test are obtained. In the diffraction pattern, the ratio of the height of the peak existing near the position where the [11-1] peak derived from the monoclinic crystal to the height of the peak existing near the position where the [111] peak derived from the tetragonal crystal is 1 is 1. It is as follows.

According to a preferred mode of the first aspect, the content of yttrium oxide in the section partial stabilized zirconia is 2 mol% 5 mol% relative to the total mol number of the oxide zirconium oxide, yttrium.

According to a second aspect of the present invention, by sintering at 1350 ° C. to 1550 ° C., the set formed product to obtain a zirconia sintered body according to the first viewpoint is provided.

According to a third aspect of the present invention, containing a low-stabilized zirconia particles you yttrium oxide, and a high stabilized zirconia particles containing a large amount of yttrium oxide than the low-stabilized zirconia particles, zirconia sintered set composition as to obtain the body (except for containing 5% to 50% of glass powder on a volume basis) is provided. The content of yttrium oxide in the low-stabilized zirconia particles is 1 mol% or more and less than 2 mol% with respect to the total number of moles of zirconium oxide and yttrium oxide. The content of yttrium oxide in the high-stabilized zirconia particles to the total mol number of the zirconium oxide yttrium oxide, 1 mol% than the content of yttrium oxide in the low-stabilized zirconia particles to the total mol number of the zirconium oxide yttrium oxide ~6mol %high.

According to the preferred form of the third aspect, the content of yttrium oxide in the highly stabilized zirconia particles is 2 mol% or more and less than 8 mol% with respect to the total number of moles of zirconium oxide and yttrium oxide .

According to a third aspect of the present invention, obtained by baking the engagement Ru set Narubutsu the second and third viewpoint at 800 ° C. C. to 1100 ° C., the calcined body to obtain a zirconia sintered body is provided The

According to a fourth aspect of the present invention, by sintering at 1400 ° C. to 1600 ° C., the calcined body to obtain a zirconia sintered body according to the first viewpoint it is provided.

  The zirconia sintered body of the present invention includes not only a sintered body obtained by sintering zirconia particles irrespective of the pressure sintering method (atmospheric pressure method sintered body) but also HIP (Hot Isostatic Pressing). A sintered body densified by an isotropic pressure process is also included.

  In the present invention, the “low temperature deterioration acceleration test” refers to a test based on ISO13356. However, the conditions defined in ISO 13356 are “134 ° C., 0.2 MPa, 5 hours”, but in the present invention, in order to make the conditions more severe, the conditions are set to “180 ° C., 1 MPa” The test time is set appropriately according to the purpose. Hereinafter, the “low temperature deterioration acceleration test” is also referred to as “hydrothermal treatment” or “hydrothermal treatment test”.

  The present invention has at least one of the following effects.

According to the present invention, it is possible to obtain the zirconia sintered body of high fracture toughness, as well as a set forming material and the calcined body to obtain the zirconia sintered body. The zirconia sintered body of the present invention can be used for various applications such as dental prosthetic materials and tools.

The graph which shows the measurement test result of the fracture toughness value in an Example.

  The contents described in the claims, specification, drawings, and abstract of Japanese Patent Application No. 2009-192287 are incorporated herein by reference.

  The zirconia sintered body of the present invention will be described. The zirconia sintered body of the present invention is a sintered body in which partially stabilized zirconia crystal particles are mainly sintered, and has partially stabilized zirconia as a matrix phase. Examples of the stabilizer in the partially stabilized zirconia crystal particles include oxides of oxides such as calcium oxide, magnesium oxide, yttrium oxide, and cerium oxide. The stabilizer is preferably added in such an amount that the zirconia particles can be partially stabilized. For example, when yttrium oxide is used as a stabilizer, the content of yttrium oxide is preferably 2 mol% to 5 mol% (about 3 mass% to 9 mass%) with respect to the total number of moles of zirconium oxide and stabilizer. Can be added. The content of the stabilizer in the zirconia sintered body can be measured, for example, by inductively coupled plasma (ICP) emission spectroscopy.

  In the following description, what is simply referred to as “zirconia” shall mean partially stabilized zirconia.

  It is preferable that the stabilizer exists in the zirconia sintered body as a whole non-uniformly. The degree of heterogeneity of the stabilizer can be represented, for example, by the standard deviation of the stabilizer concentration. When the concentration of the stabilizer on the sample surface of the zirconia sintered body is expressed in mass%, for example, the standard deviation of the stabilizer concentration in a portion of a total of 50,000 points or more is 0.8 or more, more preferably 1 As described above, more preferably 1.5 or more. The standard deviation of the stabilizer concentration is preferably 2 or less. When the standard deviation of the stabilizer concentration is 0.8 or more, the fracture toughness value of the zirconia sintered body can be increased. If the standard deviation of the stabilizer concentration is greater than 2, the instability becomes too high.

  The standard deviation is preferably calculated from the concentration of 50,000 points or more in the region of 10 μm × 10 μm of the sample surface of the zirconia sintered body. For example, as a method for measuring the standard deviation of the stabilizer concentration, for example, on the sample surface of the zirconia sintered body, a square region of 10 μm × 10 μm is divided into a grid of 256 cells in the vertical direction and 256 cells in the horizontal direction. The concentration of the stabilizer in the mass (total 65536 mass) is measured, and the standard deviation is obtained.

  As a method for measuring the concentration of the stabilizer on the sample surface of the zirconia sintered body, for example, a stabilizer on the sample surface using a field emission electron probe microanalyzer (FE-EPMA) or the like is used. Concentration can be measured. A method of collecting a part of the zirconia sintered body and measuring the concentration without depending on the sample surface concentration may be used.

Stabilizer concentration in the zirconia sintered body, the standard deviation, the matters relating to the measuring method and the like is the same even calcined body, the description thereof is omitted here.

  The zirconia sintered body of the present invention preferably contains at least one element (hereinafter referred to as “Group 15 element”) of phosphorus (P), arsenic (As), antimony (Sb), and bismuth (Bi). . By containing the Group 15 element, it is possible to suppress the phase transition to the monoclinic crystal by the low temperature deterioration acceleration test. Moreover, fracture toughness can also be improved. Of the Group 15 elements, it is preferable to use at least one of phosphorus, antimony and bismuth from the viewpoint of safety. Among these, phosphorus is particularly preferable from the viewpoint of the effect of suppressing the phase transition, the strength of the sintered body, and the cost.

The content of the Group 15 element in the zirconia sintered body of the present invention is preferably 4 × 10 ⁻⁴ mol to 4 × 10 ⁻² mol with respect to 1 mol of zirconium (IV) oxide, and 4 × 10 ⁻³ mol to 3 × 10 ⁻² mol is more preferable, and 8 × 10 ⁻³ mol to ² × 10 ⁻² mol is more preferable. This is because when the content of the Group 15 element is within this range, the effect of suppressing the phase transition from tetragonal to monoclinic appears.

  When using phosphorus as the Group 15 element, from the viewpoint of the effect of suppressing the phase transition, the phosphorus content in the zirconia sintered body is 0.01% by mass to 1% by mass with respect to the total mass of zirconium oxide and yttrium oxide. %, Preferably 0.1% to 0.6% by mass, and more preferably 0.2% to 0.5% by mass.

  The content of the Group 15 element in the zirconia sintered body can be measured by composition analysis of the zirconia sintered body. Further, the content ratio of the Group 15 element in the raw zirconia particles and the addition ratio of the Group 15 element added at the time of preparing the zirconia sintered body (that is, the content ratio before firing) of the Group 15 element in the zirconia sintered body are determined. You may consider content rate (namely, content rate after baking). However, when a certain component disappears from the zirconia sintered body by firing, and the content before firing and the content after firing cannot be substantially equated, the composition analysis is performed. The content of the Group 15 element in the zirconia sintered body can be measured, for example, by inductively coupled plasma (ICP) emission spectroscopic analysis.

  The Group 15 element may be included in the zirconia crystal grains or may be present in the crystal grain boundaries. That is, the Group 15 element may be added when the zirconia crystal particles are produced, or the zirconia crystal particles and the Group 15 element may be mixed and formed into a predetermined shape.

  The zirconia sintered body of the present invention preferably contains aluminum oxide (alumina). When aluminum oxide is contained, the progress of low-temperature deterioration can be suppressed. Moreover, since the thermal expansion coefficient of a zirconia sintered compact can be approximated to the thermal expansion coefficient of glass, generation | occurrence | production of a defect can be suppressed when using, for example as a dental prosthetic material. The content of aluminum oxide in the zirconia sintered body of the present invention is preferably 0.2% by mass to 10% by mass with respect to the total mass of zirconium oxide, yttrium oxide and aluminum oxide, and 6% by mass to 10% by mass. % Is more preferable.

  The content of aluminum oxide in the zirconia sintered body can be measured by composition analysis of the zirconia sintered body. Further, the content of aluminum oxide in the raw zirconia particles and the addition rate of aluminum oxide added during the preparation of the zirconia sintered body (that is, the content before firing) are the content of aluminum oxide in the zirconia sintered body (that is, after firing). Content rate). However, when a certain component disappears from the zirconia sintered body by firing, and the content before firing and the content after firing cannot be substantially equated, the composition analysis is performed. The content of aluminum oxide in the zirconia sintered body can be measured, for example, by inductively coupled plasma (ICP) emission spectroscopic analysis.

  Aluminum oxide may be included in the zirconia crystal grains or may exist in the crystal grain boundaries. That is, aluminum oxide may be added at the time of preparing zirconia crystal particles, or zirconia crystal particles and aluminum oxide may be mixed and formed into a predetermined shape.

  The zirconia sintered body of the present invention preferably further contains silicon dioxide. When the Group 15 element (particularly phosphorus) and silicon dioxide are contained in the zirconia sintered body, the effect of suppressing the phase transition can be further enhanced than when only the Group 15 element is contained. The content of silicon dioxide in the zirconia sintered body of the present invention is 0.03 mass% to 3 mass% with respect to the total mass of zirconium oxide, yttrium oxide and silicon dioxide from the viewpoint of the effect of suppressing the phase transition. Preferably, it is more preferably 0.05% by mass to 1% by mass, and further preferably 0.1% by mass to 0.8% by mass.

  The content of silicon dioxide in the zirconia sintered body can be measured by composition analysis of the zirconia sintered body. In addition, the content of silicon dioxide in the raw zirconia particles and the addition rate of silicon dioxide added at the time of preparing the zirconia sintered body (that is, the content before firing) are the content of silicon dioxide in the zirconia sintered body (that is, after firing). Content rate). However, when a certain component disappears from the zirconia sintered body by firing, and the content before firing and the content after firing cannot be substantially equated, the composition analysis is performed. The content of silicon dioxide in the zirconia sintered body can be measured, for example, by inductively coupled plasma (ICP) emission spectroscopy.

  Silicon dioxide may be included in the zirconia crystal grains or may exist in the crystal grain boundaries. That is, silicon dioxide may be added at the time of preparing zirconia crystal particles, or zirconia crystal particles and silicon dioxide may be mixed and formed into a predetermined shape.

  The crystal form of the zirconia crystal particles in the zirconia sintered body of the present invention is mainly tetragonal. In the zirconia sintered body of the present invention, it is preferable that the monoclinic crystal is not substantially detected in the X-ray diffraction pattern in the untreated state at the low temperature deterioration acceleration test (hydrothermal test). Even if monoclinic crystals are contained in the zirconia sintered body of the present invention (untreated hydrothermal test state), in the X-ray diffraction pattern, a [111] peak derived from a tetragonal crystal with 2θ of around 30 ° is generated. The ratio of the height of the peak existing near the position where the [11-1] peak derived from the monoclinic crystal whose 2θ is around 28 ° to the height of the existing peak (ie, “monoclinic when 2θ is around 28 °) The height of the peak existing near the position where the [11-1] peak derived from the crystal occurs / the height of the peak existing near the position where the [111] peak derived from the tetragonal crystal with 2θ of around 30 ° occurs. Is; hereinafter referred to as “peak ratio”) is preferably 0.2 or less, and more preferably 0 to 0.1.

The fracture toughness value of the zirconia sintered body of the present invention is preferably 6 MPa · m ^1/2 or more, more preferably 8 MPa · m ^1/2 or more, in a state where the low temperature deterioration acceleration test has not been performed. The fracture toughness value is measured according to JIS R1607.

  The bending strength of the zirconia sintered body of the present invention is preferably 1000 MPa or more, more preferably 1100 MPa or more, in a state where the low temperature deterioration acceleration test has not been processed. The bending strength is measured according to JIS R1601.

  The preferred zirconia sintered body of the present invention containing a Group 15 element suppresses the phase transition from tetragonal to monoclinic even when subjected to a hydrothermal treatment test (low temperature degradation accelerated test) which is an accelerated test of low temperature degradation. be able to. In particular, the effect of suppressing the phase transition is remarkable for the sintered body fired at 1450 ° C. or higher. For example, when hydrothermal treatment at 180 ° C. and 1 MPa for 5 hours is performed on the zirconia sintered body of the present invention, the peak ratio in the X-ray diffraction pattern on the surface of the zirconia sintered body after hydrothermal treatment is preferably 1 or less More preferably, it is 0.5 or less, More preferably, it is 0.1 or less, More preferably, it is 0.05 or less, More preferably, it is 0.01 or less.

  Further, when hydrothermal treatment is performed at 180 ° C. and 1 MPa for 24 hours on the zirconia sintered body of the present invention, the peak ratio is preferably in the X-ray diffraction pattern on the surface of the zirconia sintered body after hydrothermal treatment. Is 3 or less, more preferably 2 or less, still more preferably 1.5 or less, still more preferably 1 or less, and still more preferably 0.5 or less.

  The preferred zirconia sintered body of the present invention can maintain its bending strength at a high level even when subjected to a hydrothermal treatment test. For example, when the zirconia sintered body of the present invention is subjected to hydrothermal treatment at 180 ° C. and 1 MPa for 24 hours, the bending strength of the zirconia sintered body after hydrothermal treatment measured according to JIS R1601 is preferably It is 50 MPa or more, More preferably, it is 100 MPa or more, More preferably, it is 500 MPa or more, More preferably, it is 800 MPa or more, More preferably, it is 1000 MPa or more.

  The preferred zirconia sintered body of the present invention has a small dimensional change even when subjected to a hydrothermal treatment test, and can maintain high dimensional accuracy. When the zirconia sintered body of the present invention is subjected to hydrothermal treatment at 180 ° C. and 1 MPa for 24 hours, the coefficient of expansion of the width of the test piece of the zirconia sintered body after hydrothermal treatment produced according to JIS R1601 Is preferably 0.6% or less, more preferably 0.5% or less, still more preferably 0.3% or less, and further preferably 0% or less with respect to the width of the test piece subjected to non-hydrothermal treatment. .1% or less, and more preferably 0.05% or less.

  The particle size of the crystal particles in the zirconia sintered body of the present invention is not particularly limited.

  The effect of suppressing the phase transition in the zirconia sintered body of the present invention is not affected by the particle size in the zirconia sintered body. Therefore, a suitable particle size can be selected appropriately according to the application.

  The zirconia sintered body of the present invention preferably has translucency and is not colored. Thereby, the external appearance of the zirconia sintered compact can be adjusted according to a use by adding a pigment etc. to this invention. For example, the zirconia sintered body of the present invention can be suitably used as a dental material such as a prosthetic material. Moreover, it is preferable that the zirconia sintered body does not have a matte feeling and has an appearance that does not look unsintered.

  In the present invention, by including at least one of the Group 15 element and silicon dioxide in the zirconia sintered body, the fracture toughness can be increased without paying particular attention to the particle size and particle size distribution of the zirconia crystal particles. It is possible to obtain a zirconia sintered body having a low temperature deterioration property while being increased. Further, since the sintering temperature can be increased, the bending strength can be increased. Thereby, a zirconia sintered body having high fracture toughness, high strength and long-term stability can be obtained. The effects and advantages of the addition of Group 15 elements and silicon dioxide are described in the claims, specifications and drawings of Japanese Patent Application No. 2009-192287, and the detailed description in this document is incorporated herein by reference. Is omitted.

Next, the set formed product to obtain a zirconia sintered body of the present invention and the calcined body will be described. Set forming material and the calcined body is to be the precursor of the zirconia sintered body of the present invention (an intermediate product). The set formed product, powder, fluid powder was added to the solvent, and the molded element of the powder into a predetermined shape is also included.

Set composition as the present invention contains a low-stabilized zirconia particles not containing or containing a stabilizing agent, and a high stabilized zirconia particles containing a large amount of stabilizer than the low-stabilized zirconia particles. That is, a plurality of zirconia particles having different stabilizer contents (or concentrations) are mixed. The content of the stabilizer in the low-stabilized zirconia particles is preferably 0 mol% or more and less than 2 mol% with respect to the total number of moles of zirconium oxide and the stabilizer. The content of the stabilizer in the highly stabilized zirconia particles is preferably 2 mol% or more and less than 8 mol% with respect to the total number of moles of zirconium oxide and the stabilizer. The stabilizer content of the highly stabilized zirconia particles is preferably 0.5 mol% to 7 mol% higher than the stabilizer content of the low stabilized zirconia particles, more preferably 1 mol% to 7 mol% higher. More preferably, it is higher by 5 mol% to 7 mol%. For example, the stabilizer content of the low-stabilized zirconia particles can be 1 mol%, and the stabilizer content of the highly-stabilized zirconia particles can be 3 mol%. Regarding the mixing ratio of the low-stabilized zirconia particles and the highly-stabilized zirconia particles, the content of the low-stabilized zirconia particles is 5% by mass to 40% by mass with respect to the total mass of the low-stabilized zirconia particles and the high-stabilized zirconia particles. %, More preferably 10% by mass to 30% by mass, and even more preferably 15% by mass to 25% by mass. This provides a standard deviation in stabilizer concentration that can increase fracture toughness.

  In the present invention, “highly stabilized” and “lowly stabilized” and two types of zirconia particles are mixed, but three or more types of zirconia particles having different stabilizer contents may be mixed. . In this case, the standard deviation of the stabilizer concentration is adjusted by appropriately adjusting the stabilizer content and the mixing ratio of each zirconia particle.

Set composition as the present invention, preferably contains a Group 15 element or Group 15 element-containing compound. The group 15 element simple substance or the group 15 element-containing compound may be contained in the zirconia crystal particles or may exist between the zirconia crystal particles. The zirconia crystal particles may be granulated . The content of the Group 15 element in the set Narubutsu is preferable to be ^{4 × 10 -4 mol~4 × 10 -2} mol relative to zirconium oxide ^{(IV) 1mol, 4 × 10} -3 mol~3 × 10 ⁻² mol is more preferable, and 8 × 10 ⁻³ mol to ² × 10 ⁻² mol is further preferable. In addition, when the group 15 element-containing compound contains two or more group 15 elements in one molecule, the content of the group 15 element is not the number of moles of the group 15 element-containing compound, but the group 15 element content. Calculated based on the number of moles. Preferably the case group 15 element is phosphorus, in terms of phase transition suppression effect, the content of phosphorus in the set Narubutsu, 0.01 mass% to 1 mass% with respect to partially stabilized zirconia particles, More preferably, it is 0.1 mass%-0.6 mass%, and it is further more preferable that it is 0.2 mass%-0.5 mass%.

Set composition as the present invention, preferably contains aluminum oxide. Aluminum oxide may be contained in the zirconia crystal particles or may exist between the zirconia crystal particles . The content of aluminum oxide in the set Narubutsu is zirconium oxide, based on the total weight of yttrium oxide and aluminum oxide, and preferably to be 0.2 wt% to 10 wt%, and 6 wt% to 10 wt% More preferred.

Set composition as the present invention preferably further contains silicon dioxide. Silicon dioxide may be contained in the zirconia crystal particles or may exist between the zirconia crystal particles. The inclusion in the Group 15 element (in particular phosphorus) and the set formed was a silicon dioxide, it can be from time to incorporate only the Group 15 elements, further increasing the phase transition inhibitory effect on the low temperature degradation of the zirconia sintered body . The content of silicon dioxide in the composition of the present invention is preferably 0.03% by mass to 3% by mass, and 0.05% by mass to 1% with respect to the partially stabilized zirconia particles, from the viewpoint of the effect of suppressing phase transition. More preferably, it is more preferably 0.1% by mass to 0.8% by mass.

  The particle size and particle size distribution of the zirconia crystal particles are not particularly limited.

Set Narubutsu may be a powder, may be one which is formed, may be in a solvent, may contain a solvent. Also, the set Narubutsu may be those containing an additive binder or the like.

Set composition as the present invention, when a molded body is good, for example press molding, injection molding, can be assumed to have been formed by stereolithography which has been molded by any molding method, multistage It may be subjected to various moldings. For example, a set composition as the present invention after press-forming, further CIP (Cold Isostatic Pressing; cold hydrostatic isostatic pressing) process may be one subjected to.

Set composition as the present invention will become zirconia sintered body of the present invention by firing at 1350 ° C. to 1550 ° C..

Calcined body of the present invention include those which zirconia particles are fired set composition as the present invention at a temperature that does not lead to sintering, or zirconia particles set composition as the present invention is partially or partially sintered It is a thing. Provisional Group 15 element content in the baked body, an aluminum oxide content and silicon dioxide content of the present invention is similar to that of the set composition as the present invention, description thereof will be omitted.

Calcined body of the present invention is obtained by firing the set composition as the present invention at 800 ° C. C. to 1100 ° C.. On the sample surface of the calcined body, the stabilizer is preferably present in a non-uniform manner as a whole.

  The calcined body of the present invention becomes the zirconia sintered body of the present invention by firing at 1350 ° C. to 1600 ° C.

Then, the zirconia sintered body of the present invention, as well as the set formed of the zirconia sintered body and a method for manufacturing a calcined body will be described.

  Hereinafter, as an embodiment of the present invention, a manufacturing method in the case where a desired amount of Group 15 element and silicon dioxide are not contained in zirconia crystal particles will be described.

  First, highly stabilized zirconia crystal particles and low stabilized zirconia crystal particles are prepared. The stabilizer concentration in the highly stabilized zirconia particles and the low stabilized zirconia particles is as described above. As the particle size and particle size distribution of the zirconia crystal particles, suitable ones are appropriately selected.

Second, the high-stabilized zirconia crystal particles, and a low-stabilized zirconia crystal particles, the Group 15 element-containing compounds or Group 15 element alone and a mixture of, to produce a set composition as the present invention. Hereinafter, a mixture of highly stabilized zirconia crystal particles and low stabilized zirconia crystal particles is referred to as “zirconia crystal particles”. First, zirconia crystal particles and a Group 15 element-containing compound or a Group 15 element simple substance are mixed. The Group 15 element is preferably contained in an amount of 4 × 10 ⁻⁴ mol to 4 × 10 ⁻² mol with respect to 1 mol of zirconium (IV) oxide, and more preferably in an amount of 4 × 10 ⁻³ mol to ³ × 10 ⁻² mol. Preferably, 8 × 10 ⁻³ mol to ² × 10 ⁻² mol are more preferable. When two or more Group 15 elements are contained in one molecule of a Group 15 element-containing compound, the calculation is based on the number of moles of the Group 15 element, not the number of moles of the Group 15 element-containing compound.

When a phosphorus-containing compound is used as the Group 15 element-containing compound, the phosphorus-containing compound may be either an inorganic compound or an organic compound. When an inorganic compound is used, for example, phosphoric acids and phosphates can be used. In this case, for example, phosphoric acid (H ₃ PO ₄ ), aluminum phosphate (AlPO ₄ ), magnesium phosphate (Mg ₃ (PO ₄ ) ₂ ), calcium phosphate (Ca ₃ (PO ₄ ) ₂ ), magnesium hydrogen phosphate (MgHPO ₄ ), magnesium dihydrogen phosphate (Mg (H ₂ PO ₄ ) ₂ ), calcium hydrogen phosphate (CaHPO ₄ ), ammonium dihydrogen phosphate ((NH ₄ ) H ₂ PO ₄ ), etc. Can do. Moreover, when using an organic compound, phosphine oxides can be used, for example.

  When using an arsenic-containing compound as the Group 15 element-containing compound, for example, an arsenic oxide compound or the like can be used.

  When an antimony-containing compound is used as the Group 15 element-containing compound, an antimony oxide compound or the like can be used.

  When a bismuth-containing compound is used as the Group 15 element-containing compound, a bismuth oxide compound or the like can be used.

  When the zirconia sintered body of the present invention is used for a human body like a dental prosthetic material, the Group 15 element-containing compound is preferably one that has a small adverse effect on the human body, and is harmless to the human body. Is more preferable.

The set formed product, preferably further addition of silicon dioxide. Silicon dioxide is 0.03% by mass to 3% by mass, more preferably 0.05% by mass to 1% by mass, and still more preferably 0.1% by mass with respect to the total mass of zirconium oxide, yttrium oxide and silicon dioxide. It is preferable to contain ~ 0.8 mass%.

The set formed product, preferably further addition of aluminum oxide. The content of aluminum oxide is preferably 0.2% by mass to 10% by mass, and more preferably 6% by mass to 10% by mass with respect to the total mass of zirconium oxide, yttrium oxide, and aluminum oxide.

The set formed product, may be added to the binder. The presence or absence of the addition of the binder can be appropriately selected according to the purpose of manufacturing the sintered body. When using a binder, for example, an acrylic binder can be used.

  The mixing method may be either dry mixing or wet mixing. In the case of wet mixing, for example, water, alcohol or the like can be used as a solvent. Further, the mixing may be manual mixing or mechanical mixing. When the zirconia crystal particles before mixing form secondary particles, it is preferable to pulverize and mix the secondary particles as much as possible.

Third, to compression molding a set Narubutsu into a desired shape. As the pressure molding method, a suitable method can be appropriately selected. The pressurizing pressure can be set to 20 MPa or more, for example. After pressure molding, the set formed product, for example at a pressure greater than or equal to 150 MPa, CIP; may be further subjected to (Cold Isostatic Pressing cold hydrostatic isostatic pressing).

Before pressing, the set Narubutsu may be the ones to granulate the zirconia particles into granules. When a solvent is used during mixing, the solvent is first removed before pressure molding or pre-molding. For example, the solvent may be removed by a spray drier when granulated into granules, or may be removed by oven drying.

Set Narubutsu after pressure molding, by machining or grinding or the like, it can also be processed into a desired shape.

Fourth, prior to sintering, the set Narubutsu may be produced calcined to calcined body. In this case, the calcination conditions are, for example, a calcination temperature of 800 ° C. to 1100 ° C. and a holding time of 1 hour to 3 hours.

  The calcined body can be processed into a desired shape by cutting or grinding after calcining.

Fifth, by firing a set Narubutsu or calcined body, the zirconia particles by sintering, to produce a zirconia sintered body. The firing temperature is preferably 1350 ° C. or higher. When a Group 15 element is contained, the firing temperature is preferably 1450 ° C. or higher. If the firing temperature is low, the strength of the zirconia sintered body will be low. Moreover, the higher the firing temperature, the higher the effect of suppressing phase transition in low temperature degradation. For example, the zirconia sintered body of the present invention, preferably fired at a firing temperature higher than 1500 ° C., more preferably higher than 1550 ° C., can effectively suppress the phase transition to monoclinic crystals due to hydrothermal treatment. it can.

  Firing can be carried out in an atmospheric air atmosphere.

  Sixth, the zirconia sintered body may be further subjected to HIP treatment in order to improve the denseness.

In the above description of the method for producing a zirconia sintered body, the case where the desired amount of the Group 15 element-containing compound and silicon dioxide are not contained in the zirconia crystal particles has been described, but the desired amount of the Group 15 element is contained. At least one of the compound and silicon dioxide may be originally included in the zirconia crystal particles, or a part of a desired amount may be included in the zirconia crystal particles. In that case, the amount of each additive is adjusted in consideration of the content of the Group 15 element-containing compound or silicon dioxide in the zirconia crystal particles. For example, if it is contained in the desired amount of silicon dioxide in the zirconia crystal grains, the set Narubutsu during manufacturing may be added only Group 15 element-containing compound. Further, when a portion of the silicon dioxide of a desired amount into the zirconia crystal particles are contained, the set Narubutsu when made with a Group 15 element-containing compound may be added to silicon dioxide of a desired amount of balance. The rest is the same as the above method.

[Manufacture of zirconia sintered body]
A zirconia sintered body using yttria as a stabilizer was prepared. Table 1 shows the yttria content of the highly stabilized zirconia crystal particles (manufactured by Noritake Company Limited) and the low stabilized zirconia crystal particles (manufactured by Noritake Company Limited) used in Examples 1 to 4. The content ratio of yttrium oxide with respect to the total number of moles of zirconium oxide and yttrium oxide is shown. While beating high-stabilized zirconia crystal particles and the low-stabilized zirconia particles, to produce a set Narubutsu by mixing water with the formulation shown in Table 1. In Examples 2 and 4, the content of elemental phosphorus is added to the set growth was phosphate so that as shown in Table 1 with respect to the total mass of the zirconia particles and yttria. Moreover, silicon dioxide is added so that it may become Table 1 with respect to the total mass of a zirconia particle, a yttria, and silicon dioxide, and aluminum oxide will become Table 1 with respect to the total mass of a zirconia particle, a yttria, and aluminum oxide. Added to.

Next, the solvent was removed by a spray dryer and zirconia particles were granulated into granules. Then, by molding by Ri set Narubutsu to the press of 30MPa, has a diameter of 19mm, with a thickness of 2mm shape. Furthermore, the set Narubutsu is, 1400 ° C., HIP at 170 MPa; subjecting the (Hot Isostatic Pressing hot hydrostatic isostatic pressing) process for tightening. Then, each set Narubutsu was calcined 1.5 hours at each temperature shown in Table, to prepare a zirconia sintered body.

As a comparative example, a zirconia sintered body having a small concentration variation of the stabilizer was produced. In Comparative Examples 1 and 2, only one type of zirconia crystal particles is used. The main composition is shown in Table 2. In Comparative Example 1, the zirconia powder used as a raw material, a 5.2 ± 0.5 wt% yttrium oxide in the crystal grain (3 mol%) content to distearate zirconia powder (manufactured by Tosoh Corporation; No. TZ-3Y- E) only. The silicon dioxide content in the zirconia powder is 0.02% by mass or less (product standard value), and the alumina content is 0.1% by mass to 0.4% by mass (product standard value). In Comparative Example 2, zirconia powder used as a raw material, 5.2 wt% of yttrium oxide in the crystal grain (3 mol%), silicon dioxide 0.1 wt%, you containing about 0.5 wt% of alumina di zirconia powder (manufactured by Noritake Co., Ltd.) is the only. In the comparative example, no phosphorus-containing compound is added.

[Measurement of yttria concentration in zirconia sintered body]
The yttria concentration distribution in the cross section of the zirconia sintered compact concerning an Example and a comparative example was measured. Pre-processing was performed to obtain a measurement surface for concentration distribution. First, the surface of the zirconia sintered body was mechanically mirror-polished with No. 2000 abrasive. Next, the polished surface was thermally etched at 1350 ° C. for 10 minutes, and this region was used as a measurement surface. The yttria concentration on the measurement surface was measured with a field emission electron probe microanalyzer (FE-EPMA) (JXA-8500F manufactured by JEOL Ltd.). In this concentration measuring apparatus, a measurement region of 10 μm × 10 μm is divided into 256 vertical and 256 horizontal grids, and the yttria concentration in each mass is measured at a magnification of 10,000 times. The standard deviation was calculated from the measured concentration of 65,536 points in total. The results are shown in Table 1.

  By producing a zirconia sintered body by mixing a plurality of zirconia particles having different yttria concentrations, the zirconia sintered body having a large standard deviation of the stabilizer concentration compared to a zirconia sintered body produced from one kind of zirconia particles. I was able to get a body.

  Fracture toughness measurement and bending strength measurement were performed on the zirconia sintered bodies of the present invention according to Examples and Comparative Examples.

[Fracture toughness measurement test]
The fracture toughness value measurement test was performed in accordance with JIS R1607. The measurement results are shown in Tables 1 and 2. FIG. 1 is a graph showing the change in fracture toughness value (vertical axis) with respect to the standard deviation (horizontal axis) of the stabilizer concentration. Examples are indicated by black square plots, and comparative examples are indicated by white circle plots. FIG. 1 shows that the standard deviation of the stabilizer concentration and the fracture toughness value are in a proportional relationship. In the zirconia sintered bodies of Examples 1 to 4 in which the standard deviation of the stabilizer concentration is increased, the fracture toughness value is further increased as compared with the zirconia sintered bodies of Comparative Examples 1 and 2 produced by a normal method. I was able to.

  The fracture toughness value could be increased when the aluminum oxide content was at least 0.2 mass% to 10 mass%. Also, the fracture toughness value was not affected by the presence or absence of phosphorus. That is, it has been found that by containing phosphorus, a hydrothermal deterioration suppressing effect can also be imparted (see Japanese Patent Application No. 2009-192287).

  Further, in the present invention, it was found that if the sintering temperature range is at least 1350 ° C. to 1550 ° C., the sintering temperature does not significantly affect the fracture toughness value.

[Bending strength measurement test]
The bending strength test was performed according to JIS R1601. The measurement results are shown in Tables 1 and 2. It was found that increasing the standard deviation of the stabilizer concentration did not affect the bending strength. From this, according to this invention, a fracture toughness value can be raised, without reducing bending strength.

  In the above description, when calculating the number of moles of the Group 15 element with respect to 1 mole of zirconium oxide (molecular weight 123.22), the presence of a stabilizer (for example, yttrium oxide) and other compounds is considered. The zirconium oxide content in the zirconia powder is 94.5% (regardless of the silicon dioxide content).

  In the above description, numerical values indicating the upper limit and the lower limit in the range represented by “to” are included in the range.

Zirconia sintered body of the present invention, as well as the set formed product and the calcined body of the zirconia sintered body has been described based on the above embodiment, without being limited to the above embodiments, within the scope of the present invention However, it is needless to say that various modifications, changes and improvements can be included in the above embodiment based on the basic technical idea of the present invention. Further, various combinations, substitutions, or selections of various disclosed elements are possible within the scope of the claims of the present invention.

  Further problems, objects, and developments of the present invention will become apparent from the entire disclosure of the present invention including the claims.

  The zirconia sintered body of the present invention has advantages such as high strength, high toughness, long life, high reliability, small dimensional change, non-coloring property / translucency, etc., dental materials such as prosthetic materials, ferrules, sleeves, etc. Connection parts for optical fibers, various tools (for example, pulverized balls, cutting tools), various parts (for example, screws, bolts and nuts), various sensors, electronic parts, ornaments (for example, watch bands), etc. It can be used for

Claims (14)

Having partially stabilized zirconia as a matrix phase containing yttrium oxide as a stabilizer,
The standard deviation of the surface concentration of yttrium oxide when the concentration of yttrium oxide in each mass obtained by dividing a 10 μm × 10 μm region into a grid of 256 cells × 256 cells on the sample surface of the zirconia sintered body is expressed in mass%. Is 0.8 or more (provided that when 5% to 50% of crystallized glass is contained on a volume basis and when heat-treated at 200 ° C. for 100 hours in the atmosphere, 10% or more of zirconia crystals are single. A zirconia sintered body characterized by excluding those existing as oblique crystals) . Zirconia sintered body according to claim 1, characterized in that it contains phosphorus (P) element ^{4 × 10 -4 mol~4 × 10 -2} mol of the acid zirconium (IV) 1 mol. The zirconia sintered body according to claim 2 , wherein the phosphorus element content is 0.01 mass% to 1 mass%. The zirconia sintered body according to any one of claims 1 to 3 , wherein the standard deviation is 2 or less. The zirconia sintered body according to any one of claims 1 to 4 , further comprising 0.2% by mass to 10% by mass of aluminum oxide. The zirconia sintered body according to any one of claims 1 to 5 , further comprising 0.03% by mass to 3% by mass of silicon dioxide. The zirconia sintered body according to any one of claims 1 to 6 , wherein a fracture toughness value of the zirconia sintered body measured in accordance with JIS R1607 is 6 MPa · m ^1/2 or more. When the zirconia sintered body is subjected to a low temperature deterioration acceleration test at 180 ° C. and 1 MPa for 5 hours,
In the X-ray diffraction pattern on the surface of the zirconia sintered body after the accelerated low temperature degradation test, [11-1] derived from monoclinic crystals with respect to the height of the peak existing near the position where the [111] peak derived from tetragonal crystals occurs. The zirconia sintered body according to any one of claims 1 to 7 , wherein a ratio of heights of peaks existing near positions where peaks occur is 1 or less. The content of yttrium oxide in the partially stabilized zirconia is 2 mol% to 5 mol% with respect to the total number of moles of zirconium oxide and yttrium oxide , according to any one of claims 1 to 8 . Zirconia sintered body. Set composition as to obtain a zirconia sintered body according to any one of claims 1 to 9 by the sintering at 1350 ° C. to 1550 ° C.. A low-stabilized zirconia particles you yttrium oxide,
High-stabilized zirconia particles containing more yttrium oxide than the low-stabilized zirconia particles (excluding those containing 5% to 50% glass powder on a volume basis) ,
The content of yttrium oxide in the low-stabilized zirconia particles is 1 mol% or more and less than 2 mol% with respect to the total number of moles of zirconium oxide and yttrium oxide,
The content of yttrium oxide in the highly stabilized zirconia particles relative to the total number of moles of zirconia and yttrium oxide is 1 mol% than the content of yttrium oxide in the low stabilized zirconia particles relative to the total number of moles of zirconium oxide and yttrium oxide. you wherein the ～6Mol% higher, set composition as to obtain a zirconia sintered body. The content of yttrium oxide in the high-stabilized zirconia particles, the set composition as claimed in claim 11, characterized in that less than 2 mol% or more 8 mol% relative to the total mol number of the oxide zirconium oxide, yttrium. Temporary Shokarada for obtaining obtained by firing the set composition as described in 800 ° C. C. to 1100 ° C. in any one of claims 10 to 12, the zirconia sintered body. Temporary Shokarada for obtaining a zirconia sintered body according to any one of claims 1 to 9 by the sintering at 1350 ° C. to 1550 ° C..