JP5094009B2 - Zirconium oxide sintered body - Google Patents

Description

  The present invention particularly relates to a semiconducting zirconium oxide used as a support jig for processing, cleaning and drying while supporting a material of a thin film magnetic head, or as a support jig for cleaning while supporting a manufactured magnetic head. Relates to a sintered material.

  In recent years, there has been a demand for improved performance of thin film magnetic heads due to the demand for rapid increase in recording density of hard disk drives. This thin film magnetic head uses an electromagnetic conversion element for writing and a magnetoresistive effect element for reproduction. In order to increase the recording density, it is indispensable to lower the flying height of the magnetic head. . Recently, the flying height of the magnetic head (the gap between the electromagnetic transducer and magnetoresistive element mounted on the magnetic head and the magnetic disk as a recording medium) has become several tens of nm.

Such a thin film magnetic head is generally manufactured as follows. A ceramic substrate made of Al ₂ O ₃ —TiC ceramics or the like is processed into a strip shape, this strip-shaped ceramic substrate is fixed to a supporting jig, washed, and then an insulating film made of amorphous alumina is formed by sputtering. On the insulating film, an electromagnetic conversion element for writing, an MR (Magnetro Resistive) element using a magnetoresistive effect for reproduction, a GMR (Giant Magnetro Resistive) element, a TMR (Tunnel Magnetro Resistive) element, etc. are mounted. . A strip-shaped ceramic substrate on which these elements are mounted is processed into a chip shape, and the divided chip-shaped ceramic is placed in a supporting jig and washed and dried. After that, this chip-shaped ceramic grinds the facing surface facing the recording medium, grooves are formed by ion milling or reactive ion etching, and then washed to form an ABS (air bearing surface) surface. Thus, a thin film magnetic head is manufactured.

  In the process of manufacturing these thin-film magnetic heads, if particles (fine particles) adhere to the ceramic substrate, the formation of electromagnetic transducers and magnetoresistive elements is obstructed, and the extremely high tens of nanometers. There arises a problem that accurate grooving cannot be performed, and further a problem that particles enter into a gap between the magnetic head and the magnetic disk as a recording medium to cause the magnetic recording apparatus to malfunction.

  These particles consist of particles floating in the atmosphere, particles adhering to a processing apparatus and supporting jig used for manufacturing a magnetic head, and processing powder generated when processing the magnetic head. There are particles and particles in which the residue of the adhesive used for fixing to the supporting jig for processing the ceramic substrate remains in the form of fine particles.

  Therefore, the supporting jig used for processing the material of the magnetic head and the supporting jig used for supporting the manufactured magnetic head must be less likely to adhere particles. Therefore, the material for the supporting jig is required to be semiconductive. In response to this requirement, a semiconductive zirconium oxide sintered body is used in which a predetermined amount of a conductive material is contained in zirconium oxide which has good mechanical properties, a large fracture toughness value and is resistant to chipping and cracking. When such a semiconductive zirconium oxide sintered body is used, no static electricity is generated in the supporting jig, so that particles do not adhere due to Coulomb force, and the material processing of the magnetic head that comes into contact with the supporting jig In addition, adhesion due to transfer of particles to the manufactured magnetic head is eliminated.

In addition, the magnetic head needs to sufficiently remove particles by washing before it is manufactured and mounted on the magnetic recording apparatus. Since cleaning using an acidic aqueous solution and an alkaline aqueous solution is performed as the cleaning solution, the supporting jig needs to be corroded and hardly generate particles when exposed to these aqueous solutions. In this respect, the semiconductive zirconium oxide sintered body is suitable as a material for the supporting jig because it is based on zirconium oxide ceramics having excellent corrosion resistance. Of the particles, those made of metal or a compound thereof are mainly removed with an acidic aqueous solution, for example, an aqueous solution containing hydrochloric acid or hydrogen fluoride, and organic substances such as proteins are removed with an alkaline aqueous solution containing sodium hydroxide. Yes.
And there are the following patent documents concerning the semiconductive zirconium oxide sintered body.

Patent Document 1 contains at least 60 to 80% by weight of ZrO ₂ containing a stabilizer and 20 to 40% by weight of ZnO as a conductivity imparting agent, and has a volume resistivity of 10 ⁵ to 10 ¹⁰ Ω. A zirconium oxide sintered body having a cm (10 ³ to 10 ⁸ Ω · m) is described.

Patent Document 2 discloses a sintered body containing ZrO ₂ containing a stabilizer as a main component and Zn and Al as subcomponents. The sintered body contains a reaction product of the Zn and Al. A semiconductive zirconium oxide sintered body having a certain ZnAl ₂ O ₄ and having a volume resistivity of 10 ³ to 10 ⁷ Ω · m is described.

Patent Document 3 discloses that 60 to 90% by weight of zirconium oxide containing a stabilizer for dysprosium oxide and cerium oxide, and 10 to 40% by weight of one or more oxides of Fe and Zn as a conductivity-imparting agent. A semiconductive zirconium oxide sintered body is described which is contained in a range, has a volume resistivity of 10 ³ to 10 ⁷ Ω · m, and has a void occupation area ratio of 1.5% or less.
JP 2004-203707 A JP 2003-48775 A JP 2003-12368 A

  However, the semiconductive zirconium oxide sintered bodies disclosed in Patent Documents 1 to 3 use a zirconium oxide ceramic having a corrosion resistance against an acidic aqueous solution or an alkaline aqueous solution, which is a cleaning solution, as a base, and phase stability to this. Zinc oxide and an element having an effect of realizing chemical conversion and semiconductivity are added. When these zirconium oxide sintered bodies are used as a supporting jig and the magnetic head is washed with an acidic aqueous solution or an alkaline aqueous solution, a large amount of zinc oxide is eluted in the cleaning solution, and the eluted zinc oxide becomes a large number of particles. The particles attached to the magnetic head itself or attached to the supporting jig are transferred to the magnetic head, and the particles enter between the magnetic head and the magnetic disk, causing the magnetic recording apparatus on which the magnetic head is mounted to malfunction. There was a problem.

  In addition, when zinc oxide is eluted in a large amount in the cleaning liquid, zinc oxide disappears from the vicinity of the surface of the zirconium oxide sintered body, so that the volume resistivity value is increased. Become a unity. For example, a large amount of particles floating in the atmosphere adhere to the supporting jig made of a zirconium oxide sintered body having no semiconductivity due to the Coulomb force, so that the adhered particles are transferred to the magnetic head. However, the magnetic recording apparatus using this magnetic head has a problem of causing malfunction.

  The reason why these problems occur is considered that the zirconium oxide sintered bodies disclosed in Patent Documents 1 to 3 have a higher Zn concentration in the vicinity of the surface than the Zn concentration inside.

  On the other hand, the zirconium oxide sintered bodies shown in Patent Documents 1 to 3 may not have zinc oxide at all in the vicinity of the surface after firing. In this case, the insulating property having a large volume resistivity value is present. This becomes a zirconium oxide sintered body. When such an insulating zirconium oxide sintered body is used as a supporting jig, there is a problem in that particles adhere due to Coulomb force, and similarly the magnetic recording apparatus malfunctions. Here, it is considered that the zinc oxide does not exist at all in the vicinity of the surface after firing because the zinc oxide is decomposed and evaporated from the vicinity of the surface during firing.

  In view of the above problems, the present invention has semiconductivity and practically sufficient mechanical properties, and the amount of particles generated from the sintered body when washed with an acidic aqueous solution or an alkaline aqueous solution is small. An object of the present invention is to provide a zirconium oxide sintered body that retains sufficient semiconductivity even after the above.

The zirconium oxide sintered body of the present invention comprises an oxide containing at least Zr as a metal element, at least one of Y, Ce and Dy, and Zn, and the Zr is 52 to 89 in terms of ZrO _2. 1% to 12% by mass in terms of Y ₂ O ₃ , CeO ₂ and Dy ₂ O ₃ , and 10 to 40% by mass in terms of ZnO In the zirconium oxide sintered body, a zinc oxide grain boundary layer continuously exists between the zirconium oxide crystals, and the zinc oxide grain boundary layer has a depth in the internal direction from the surface of the sintered body. The Zn concentration in the range up to 0.1 mm is lower than the Zn concentration inside.

In addition, the zirconium oxide sintered body of the present invention has a depth of 0.1 mm from the surface of the sintered body to the inside when the Zn concentration in the sintered body is 1 in the above configuration.
The ratio of the Zn concentration in the range is 0.8 or more.

It consists of an oxide containing at least Zr, at least one of Y, Ce, and Dy as a metal element and Zn, and the Zr is 52 to 89% by mass in terms of ZrO ₂ , of the Y, Ce, and Dy In a zirconium oxide sintered body containing at least one of Y ₁₂ O ₃ , CeO ₂ and Dy ₂ O _{3 in} terms of total amount of 1 to 12% by mass and Zn of 10 to 40% by mass in terms of ZnO, A zinc oxide grain boundary layer is continuously present between the crystals, and the zinc oxide grain boundary layer has a depth of 0.1 mm from the surface of the sintered body to the inside. The zirconium oxide sintered body of the present invention in which the Zn concentration is lower than the Zn concentration in the interior exhibits the following effects.

That is, by containing at least one of Y, Ce and Dy, it has practically sufficient mechanical properties from the effect of phase stabilization that stabilizes the crystal phase of Zr, and is composed of an oxide of Zn. Zinc oxide grain boundary layer having semiconductivity between zirconium oxide crystals by containing Zn in an amount of 10 to 40% by mass in terms of ZnO due to another effect of solid solution in crystals to exhibit semiconductivity. Therefore, a semiconductive zirconium oxide sintered body can be obtained.
In addition, by using a zirconium oxide sintered body in which the Zn concentration in the range from the surface of the sintered body to the depth of 0.1 mm to the inside is lower than the Zn concentration in the interior, there are few lattice defects and chemical Therefore, when the sintered body is washed with an acidic aqueous solution or an alkaline aqueous solution, the amount of particles generated from the sintered body can be reduced. In addition, even if the semiconductive crystals containing zinc oxide are slightly eluted from the range of the depth from the surface of the sintered body to the inside of 0.1 mm, the sintered body is sintered from the inside of the zirconium oxide sintered body. Depth from the surface to the inside is 0.1m
Zirconium oxide having sufficient semiconductivity even after washing with an acidic aqueous solution or an alkaline aqueous solution because the surface resistivity does not decrease because the zinc oxide grain boundary layer exists continuously over a range up to m. It can be a sintered body.

  Hereinafter, the best mode for carrying out the present invention will be described.

  FIG. 1 is a configuration diagram showing an example of a crystal configuration of a zirconium oxide sintered body of the present invention.

  This zirconium oxide sintered body 1 has a configuration in which a zinc oxide grain boundary layer 3 having semiconductivity exists between zirconium oxide crystals 2, and the zinc oxide grain boundary layer 3 is composed of zirconium oxide crystals 2. It consists of a zinc oxide grain boundary layer 3a continuously present between them and a zinc oxide grain boundary layer 3b present discontinuously (independently).

Zirconium oxide sintered body 1 is made of an oxide containing at least Zr as a metal element, at least one of Y, Ce and Dy and Zn, and Zr is 52 to 89% by mass in terms of ZrO ₂ , Y, Ce and Dy are each configured to contain 1 to 12% by mass in terms of Y ₂ O ₃ , CeO ₂ and Dy ₂ O _{3 in} terms of total, and Zn in an amount of 10 to 40% by mass in terms of ZnO. , Ce and Dy are dissolved in a crystal composed of an oxide of Zr to stabilize the crystal phase of the zirconium oxide crystal 2 and dissolved in a crystal composed of an oxide of Zn to form zinc oxide particles The interface layer 3 has an effect of expressing semiconductivity, and Zn is contained in an amount of 10 to 40% by mass in terms of ZnO, thereby forming the zinc oxide grain boundary layer 3 continuously present between the zirconium oxide crystals 2. Can It can be a semi-conductive path.

  The zirconium oxide crystal 2 and the zinc oxide grain boundary layers 3, 3 a, 3 b here are crystals in which at least one of Y, Ce, and Dy is dissolved in zirconium oxide and zinc oxide. It may contain inevitable impurities.

The inventor has practically sufficient mechanical properties, can reduce the amount of particles generated from the zirconium oxide sintered body 1 when washed with an acidic aqueous solution or an alkaline aqueous solution, and even after performing these washings. As a result of various investigations to obtain a zirconium oxide sintered body 1 having sufficient semiconductivity, at least one element of Y, Ce and Dy is converted into a zirconium oxide crystal 2 and a zinc oxide grain boundary. While being contained in the layer 3, the concentration of Zn in the range where the depth from the surface of the zirconium oxide sintered body 1 to the inner direction is 0.1 mm (hereinafter referred to as the vicinity of the surface) is more than the concentration of Zn in the interior . It was ascertained that the zirconium oxide sintered body 1 that achieves the above-mentioned object can be provided by lowering.

That is, the zirconium oxide sintered body 1 of the present invention is composed of an oxide containing at least Zr as a metal element, at least one of Y, Ce, and Dy and Zn, and Zr is converted into ZrO _{2 in} terms of 52. 89 wt%, Y, respectively at least one of Ce and Dy _{Y 2 O} 3, CeO 2 and _Dy 2 _{O 3} in terms of total 1-12 wt%, containing 10 to 40 mass% of Zn in terms of ZnO In the zirconium oxide sintered body 1, the zinc oxide grain boundary layer 3 a is continuously present between the zirconium oxide crystals 2, and the zinc oxide grain boundary layer 3 a has a Zn concentration in the vicinity of the surface of the sintered body. Is lower than the concentration of Zn inside.

The zirconium oxide-based sintered body 1 of the present invention contains 52 to 89% by mass of Zr in terms of ZrO ₂ , so that the zirconium oxide-based crystal 2 is the main crystal in the zirconium oxide-based sintered body 1. In addition, when at least one of Y, Ce and Dy is contained in an amount of 1 to 12% by mass in terms of Y ₂ O ₃ , CeO ₂ and Dy ₂ O ₃ , the crystalline phase is stabilized by dissolving in the main crystal. The total content of tetragonal zirconium oxide crystals and cubic zirconium oxide crystals can be 95% by volume or more of the main crystal, resulting in a high fracture toughness value and resistance to dissolution in acidic and alkaline aqueous solutions. Excellent in properties. Therefore, it is possible to obtain the zirconium oxide sintered body 1 that has mechanical characteristics particularly sufficient for practical use, and has a small amount of particles generated from the sintered body even when cleaning with an acidic aqueous solution or an alkaline aqueous solution is performed.

Here, the fracture toughness value of the tetragonal zirconium oxide crystal and the cubic zirconium oxide crystal is large because the stress-induced phase transformation strengthening mechanism (the propagation of cracks causing fracture of the sintered body is a tetragonal or cubic crystal). This is due to the action of a mechanism that hinders stress concentration at the crack tip by inhibiting the phase transformation from to to monoclinic. In addition, tetragonal zirconium oxide crystals and cubic zirconium oxide crystals are less likely to be generated when exposed to acidic aqueous solutions or alkaline aqueous solutions. It is presumed that the crystal lattice of these crystals is chemically stable even when exposed to H ⁺ ions contained in an acidic aqueous solution and OH ⁻ ions contained in an alkaline aqueous solution.

If the content of Zr is less than 52% by mass in terms of ZrO ₂ , it is difficult to make the zirconium oxide crystal 2 as a main crystal, so that a sintered body having poor mechanical properties is obtained. If the content of Zr exceeds 89% by mass in terms of ZrO ₂ , the content of semiconductive crystals decreases, so that the zinc oxide grain boundary layer 3 having semiconductive properties between the zirconium oxide crystals 2 is reduced. Can not be formed continuously, so that a sintered body having a large volume resistivity is obtained.

Further, Zn is contained in an amount of 10 to 40% by mass in terms of ZnO, and at least one of Y, Ce and Dy is contained in an amount of 1 to 12% by mass in terms of Y ₂ O ₃ , CeO ₂ and Dy ₂ O ₃ respectively. Accordingly, since the zinc oxide grain boundary layer 3 in which at least one of Y, Ce and Dy is dissolved in the zinc oxide crystal to exhibit semiconductivity can be continuously present, the volume resistivity is increased. A semiconductive zirconium oxide sintered body 1 having a value of 1 to 10 ⁶ Ω · m can be obtained.

When Zn is less than 10% by mass in terms of ZnO, the zinc oxide grain boundary layer 3 having semiconductivity cannot be continuously formed between the zirconium oxide crystals 2, so that the volume resistivity value of the zirconium oxide sintered body 1 is reduced. Exceeding 10 ⁶ Ω · m, semi-conductivity is lost, static electricity cannot be released, and if it exceeds 40% by mass, the fracture toughness value is small, so the mechanical properties of the zirconium oxide sintered body 1 In addition, since the volume resistivity value is less than 1 Ω · m, the static electricity easily escapes at a stretch, and there is a risk of damaging the electromagnetic conversion element, the magnetoresistive effect element, or the like due to spark or the like.

In addition, if at least one of Y, Ce and Dy having the effects of phase stabilization and semiconductivity expression is contained in a total amount of less than 1% by mass in terms of Y ₂ O ₃ , CeO ₂ and Dy ₂ O ₃ , respectively. Since the total content of tetragonal zirconium oxide crystals and cubic zirconium oxide crystals is less than 95% by volume of the main crystal, the fracture toughness value is reduced and the mechanical properties are deteriorated, and cleaning with an acidic aqueous solution or alkaline aqueous solution is performed. The amount of particles generated from the sintered body increases when performing the above. If the amount is less than 1% by mass, the semiconductivity is not exhibited, and the zinc oxide grain boundary layer 3 having the semiconductivity cannot be continuously formed even if it is dissolved in zinc oxide. As a result, the sintered body is not semiconductive. On the other hand, if it exceeds 12% by mass, the zirconium oxide crystal 2 is stable, but the amount is too large, so that the mechanical properties of the zirconium oxide sintered body 1 deteriorate.

  The zinc oxide-based grain boundary layer 3 of the zirconium oxide-based sintered body 1 of the present invention has a zirconium oxide-based sintered body by making the concentration of Zn in the vicinity of the surface of the sintered body lower than the concentration of Zn inside. When the 1 is exposed to an acidic aqueous solution or an alkaline aqueous solution and cleaned, the amount of particles generated from the zirconium oxide sintered body 1 can be particularly reduced, and the semiconductivity can be maintained even after cleaning.

  In general, a zirconium oxide sintered body is decomposed from a zinc oxide grain boundary layer in the vicinity of the surface when sintered at a maximum temperature of 1250 to 1400 ° C. in the firing step, and Zn gas and oxygen It evaporates as a gas. The evaporated Zn gas and oxygen gas react with each other in the temperature lowering process to generate zinc oxide, and the generated zinc oxide adheres to the surface of the sintered body. However, when a large amount of the generated zinc oxide adheres to the surface of the sintered body, the Zn concentration near the surface of the sintered body becomes higher than the Zn concentration inside. Crystals with a structure in which the generated zinc oxide is stacked on the surface of the sintered body are chemically unstable because they have many lattice defects and are not strongly sintered with each other, and are exposed to acidic and alkaline aqueous solutions. Then, it elutes and many particles are likely to be generated.

  Decomposition / evaporation is accelerated as the flow of air around the molded body increases, and when the flow of air flows quickly, the generated zinc oxide does not adhere to the surface of the sintered body and has semiconductivity. Since the grain boundary layer cannot be continuously formed, the volume resistivity value is increased, and as a result, a zirconium oxide sintered body having no semiconductivity is obtained.

  Therefore, in order to obtain a chemically stable zirconium oxide sintered body 1 having semiconductivity, extremely few lattice defects, and specifying the gas flow rate and oxygen partial pressure in the firing furnace in the firing step. In order to suppress the decomposition / evaporation reaction of zinc oxide, it is necessary to place the compact in a shielding jig and to fire at a maximum temperature of 1250 to 1400 ° C.

  The zirconium oxide sintered body 1 obtained in this way has a Zn concentration in the vicinity of the surface lower than that in the interior, and the zinc oxide grain boundary layer 3 having semiconductivity is continuous from the inside to the vicinity of the surface. Then, the existing zinc oxide grain boundary layer 3a is formed, and the zinc oxide grain boundary layer 3a has semiconductivity, so that the zirconium oxide sintered body 1 has semiconductivity. In addition, since the crystals constituting the zinc oxide grain boundary layer 3 have few lattice defects from the inside to the vicinity of the surface and are strongly sintered to each other, they are chemically grown from the inside to the vicinity of the surface. And is less likely to elute even when exposed to an acidic aqueous solution or an alkaline aqueous solution.

  Preferably, when the concentration of Zn in the zirconium oxide sintered body 1 is 1, the ratio of Zn concentration in the vicinity of the surface is 0.8 or more. As a result, a large number of crystals constituting the zinc oxide grain boundary layer 3 are strongly sintered with each other, so that there are very few lattice defects. Therefore, it exhibits good corrosion resistance with little generation of particles with respect to high-concentration acidic aqueous solution or alkaline aqueous solution and long-time washing, and can maintain sufficient semiconductivity even after washing. In addition, since the elution of the semiconductive zinc oxide grain boundary layer 3 is less than the vicinity of the surface, the characteristics required for the supporting jig can be maintained for a long period of time, so that it can be used repeatedly. Although these causes are not clear, it is thought to be due to the following reasons.

In order to make it difficult to elute the zinc oxide grain boundary layer 3 when exposed to an acidic aqueous solution or an alkaline aqueous solution, it is necessary to extremely reduce the lattice defects of the crystals constituting the zinc oxide grain boundary layer 3. The lattice defect here means a lattice defect such as an oxygen defect in the crystal lattice or a line defect formed at the interface of the crystal lattice. Since such lattice defects are electrochemically unstable, when exposed to an external electrochemical action such as H ⁺ ions in a high concentration acidic aqueous solution or OH ⁻ ions in an alkaline aqueous solution, the lattice defects Atoms adjacent to are electrochemically bound to these ions and easily released into the solution. This electrochemical reaction occurs in a chain from the surface of the zinc oxide grain boundary layer 3 to the inside, and as a result, the zinc oxide grain boundary layer 3 tends to be eluted as particles from the vicinity of the surface. In order to suppress this electrochemical reaction, it is necessary to extremely reduce lattice defects in the zinc oxide grain boundary layer 3. If there are very few lattice defects, this electrochemical reaction is suppressed and the generation of particles is reduced. Here, if the crystals constituting the zinc oxide grain boundary layer 3 are firmly sintered, the residual stress between the crystals constituting the zinc oxide grain boundary layer 3 is small, and the crystal lattice is regularly arranged. Therefore, lattice defects such as oxygen defects in the crystal lattice and line defects formed at the interface of the crystal lattice can be extremely reduced.

  Note that the vicinity of the surface of the zirconium oxide sintered body 1 of the present invention specifically means a range in which the depth from the surface of the sintered body to the inner direction is about 0.1 mm, and the inside means the sintered body. This refers to the interior that exceeds the depth of about 0.1 mm from the surface. Here, the reason why the range in which the depth from the surface of the sintered body to the inner direction is about 0.1 mm is the vicinity of the surface is as follows.

  When the zirconium oxide sintered body 1 is exposed to a strong acidic solution or a strong alkaline solution for a long period of time, for example, several months, the zirconium oxide sintered body 1 has a depth from the surface of the sintered body to the inner direction. Is corroded to about 0.1 mm, and thereafter the corrosion rate is thought to gradually decrease. The term “corrosion” as used herein means that not only the zinc oxide grain boundary layer 3 between the zirconium oxide crystals 2 but also the zirconium oxide crystals 2 are eluted from the surface of the sintered body or degranulated. The cause of this corrosion is not scientifically clear, but it is generally considered that the logarithm of the initial corrosion rate (mm / year) is inversely proportional to the standard free energy of formation (kJ / mol) of the sintered body. Inferred from the above, in the case of the zirconium oxide sintered body 1, when it is exposed to an acidic solution or an alkaline solution for several months, it is corroded to a depth of about 0.1 mm at the initial stage of corrosion, and then the progress of the corrosion is delayed.

Therefore, since crystals with a depth of about 0.1 mm from the surface of the sintered body to the inside direction are considered to be inferior to the inside in terms of corrosion resistance, sintering will occur when exposed to acidic aqueous solutions or alkaline aqueous solutions for a long time. This is because it is important that the crystals in this range have a high corrosion resistance because the crystals in the range from the surface of the body to the inner depth of about 0.1 mm may elute or shed. .
Next, a method for analyzing the zirconium oxide sintered body 1 of the present invention will be described.

The composition of the zirconium oxide sintered body 1 of the present invention can be quantitatively measured by ICP emission spectroscopic analysis. For example, when the zirconium oxide sintered body 1 of the present invention contains Zr, Y, Zn, the contents of these elements are measured by ICP emission spectroscopic analysis, and these are measured as ZrO ₂ , Y ₂ O ₃ , ZnO. Convert to.

In order to measure the fracture toughness value of the zirconium oxide sintered body 1 of the present invention, for example, it is measured by the IF method described in JIS R 1607 (1995). Zirconium oxide sintered body 1 is mirror-polished to an arithmetic average height Ra of 0.1 μm or less, a diamond indentation terminal is pushed into the mirror surface, and the resulting indentation and cracks are observed. A value Kc (Pa · m ^1/2 ) is obtained.

Kc = (0.026E ^1/2 P ^1/2 α) / C ^3/2
Where E is the elastic modulus (Pa), P is the indentation load (N) of the indentation terminal, α is half the average diagonal length of the indentation (m), and C is the average length of cracks (cracks). Half (m).

  The elastic modulus E (Pa) can be measured by the ultrasonic pulse method described in JIS R 1602 (1995) as follows. The test piece can be obtained by the following formula by preparing a prism having a 10 mm square or more or a cylinder having a diameter of 10 mm or more, applying an ultrasonic wave to the sample.

_{^{E = ρ (3V t 2 V}} l 2 -4V t 4) / (V l 2 -V t 2)
Here, ρ is the bulk density (kg / m ³ ), V ₁ is the longitudinal wave velocity (m / s), and V _t is the transverse wave velocity (m / s).

  In order to measure the bending strength of the zirconium oxide sintered body 1 of the present invention, it can be measured as follows based on, for example, JIS R 1601 (1995).

  A test piece obtained by processing the zirconium oxide sintered body 1 and polishing it to an arithmetic average height Ra of 0.2 μm or less to obtain a thickness of 3 mm, a width of 4 mm, a length of 36 mm, and a C surface of 0.1 to 0.3 mm. Make 10 or more. A load tester is used to apply a load to the test piece, measure the maximum load until breakage, and calculate the bending strength according to the following equation.

3-point bending strength σ ₃ (N / mm ² ) = 3PL / 2 wt ²
4-point bending strength σ ₄ (N / mm ² ) = 3P (L−1) / 2 wt ²
Here, P is the maximum load (N) when the test piece breaks, L is the distance between the lower fulcrums (mm), l is the distance between the upper load points (mm), w is the width of the test piece (mm), t Is the thickness (mm) of the test piece.

The concentration of Zn inside and near the surface of the zirconium oxide sintered body 1 of the present invention is measured, for example, as follows. The analysis area surface to be measured by specifying the analysis area surface to be measured on the scanning electron microscope (SEM) observation screen inside and near the surface of the sintered body obtained by polishing the zirconium oxide sintered body 1 by 0.5 mm from the surface. The intensity of Zn element is measured by detecting the wavelength of characteristic X-rays generated by irradiation of the electron beam on a wavelength dispersive X-ray microanalyzer (WDS). The measurement conditions at this time are an acceleration voltage of about 15 kV, a probe current of about 10 ⁻⁷ A, an area of the analysis area of about 10 ³ to 10 ⁸ μm ² , and the Zn element strength is measured at least at five or more locations. And average. Confirming that the Zn concentration in the vicinity of the surface is lower than the Zn concentration in the interior by comparing the Zn element strength in the sintered body with the wavelength dispersive X-ray microanalyzer (WDS) in the vicinity of the surface. Can do. When the Zn concentration in the interior is 1, the ratio of the Zn concentration in the vicinity of the surface can be obtained by dividing the Zn element strength in the vicinity of the surface by the Zn element strength in the interior. Further, as other measurement methods, there are a method of measuring the Zn element intensity with a transmission electron microscope (TEM) and an energy dispersive X-ray microanalyzer (EDS), and a measurement method using an atomic force microscope.

The surface resistance and the volume resistivity are measured as follows in accordance with, for example, JIS C 2141 (1992). First, a disc-shaped zirconium oxide sintered body 1 of the present invention having a diameter of 50 mm and a thickness of about 2 mm is prepared, and the thickness at three locations is measured using a micrometer to obtain an average value d of the thicknesses. The diameter D ₁ on a main center of the zirconium oxide sintered body 1 prints the Ag electrode paste to be about 26mm and central electrode, at a distance of approximately 6mm from the outer periphery of the center electrode, the inner circumferential diameter D ₂ is approximately 38mm, the Ag electrode paste so that the peripheral diameter _{D 3} of about 48mm print, the peripheral electrode. Further, an Ag electrode paste is printed on the other main surface to form a back electrode. Thereafter, these Ag electrodes are baked to produce test pieces. The diameters D ₁ and D ₂ of these test pieces are accurately measured with calipers, the test pieces are dried at 120 ° C. for 2 hours or more, then cooled in a desiccator, and further kept in a room at 20 ° C. and 65% humidity for 16 hours or more. After standing, the surface resistance and volume resistivity are measured as follows using a high insulation resistance meter.

The surface resistance Rs (Ω) is measured by connecting the circuit so that the center electrode is on the negative side, the outer peripheral electrode is on the positive side, and the back electrode is a guard. The volume resistivity Rv (Ω) is measured by connecting the circuit so that the center electrode is on the negative side, the back electrode is on the positive side, and the outer peripheral electrode is a guard. Using the surface resistance Rs and the volume resistivity Rv thus measured, the surface resistivity and the volume resistivity are calculated by the following equations. In the following equation, the units of D ₁ , D ₂ , and d are calculated after being converted to m.

Surface resistivity ρs (Ω) = π (D ₁ + D ₂ ) Rs / (D ₂ −D ₁ ) (π is a circular rate)
Volume resistivity ρv (Ω · m) = π (D ₁ + D ₂ ) ² Rv / 16d (π is the circumference)
In this measurement method, a sample having a diameter of 50 mm is described as an example. However, if the sample has a disk shape with a diameter of 20 mm or more or a square with a side of 20 mm or more, for example, D ₁ is 10 mm, D ₂ is 16 mm, D _The surface resistivity and volume resistivity can also be measured by appropriately setting the values of D ₁ , D ₂ , and D ₃ to predetermined values, such as ₃ being 19 mm.

For example, the particle generation amount is measured as follows. Zirconium oxide sintered body 1 is put into a glass container containing an acidic aqueous solution, and in that state, cleaning is performed for 1 minute with an ultrasonic cleaner (BRANSON DHA-1000 manufactured by Cleansonic). Thereafter, the sintered body is taken out from the glass container, and the number (particles) of particles released into the acidic aqueous solution by ultrasonic cleaning is measured with a particle counter (KL-26 manufactured by Rion Co., Ltd.). Using the number of particles obtained by this measurement and the surface area of the sintered body, the number of particles emitted from 1 cm ² of the surface area of the sintered body is obtained, and this is defined as the amount of particles generated (number / cm ² ). . In addition, when the particle counter KL-26 is used, the number of particles is the amount of particles generated with particle sizes of 0.1 μm to less than 0.3 μm, 0.3 μm to less than 0.5 μm, and 0.5 μm or more. Piece / cm ² ).

  Next, the manufacturing method of the zirconium oxide sintered compact 1 of this invention is demonstrated.

The manufacturing method of the zirconium oxide sintered body 1 includes at least one of zirconium oxide (ZrO ₂ ) powder, yttrium oxide (Y ₂ O ₃ ), cerium oxide (CeO ₂ ), and dysprosium oxide (Dy ₂ O ₃ ). Or a mixed powder obtained by mixing zinc oxide powder in which at least one of Y, Ce and Dy is dissolved, and zinc oxide powder. A mixed powder preparation step for forming the mixture, a forming step for forming any one of the mixed powders into a predetermined shape to obtain a formed body, and a firing step for firing the obtained formed body in an air atmosphere. At this time, it is made of an oxide containing at least Zr, at least one of Y, Ce and Dy as a metal element and Zn, and Zr is 52 to 89% by mass in terms of ZrO ₂ , of Y, Ce and Dy. A mixed powder was prepared so that at least one of them was 1 to 12% by mass in terms of Y ₂ O ₃ , CeO ₂ and Dy ₂ O ₃ , and Zn was 10 to 40% by mass in terms of ZnO. In a firing step, the molded body is placed in a shielding jig, the oxygen partial pressure in the firing furnace is 0.01 to 1 MPa, and the gas flow rate in the firing furnace is 0.1 to 1 Nm ³ / min. As a result, the zinc oxide grain boundary layer 3 is continuously present between the zirconium oxide crystals 2, and the concentration of Zn in the zinc oxide grain boundary layer 3 is determined in the vicinity of the surface of the sintered body. Zn concentration inside Zirconium oxide sintered body 1 having a concentration lower than the above concentration can be produced.

  Specifically, the manufacturing method of the zirconium oxide sintered body 1 of the present invention is as follows.

(1) High-purity zirconium oxide (ZrO ₂ ) powder having an average particle size of 1 μm or less, yttrium oxide (Y ₂ O ₃ ) powder, cerium oxide (CeO ₂ ) powder, dysprosium oxide (Dy ₂ O ₃ ) powder, And zinc oxide (ZnO) powder, ZrO ₂ powder is 52 to 89% by mass, and at least one of Y ₂ O ₃ powder, CeO ₂ powder and Dy ₂ O ₃ powder or 1 to 12% by mass in total And ZnO powder is mixed uniformly so that it may become 10-40 mass%, and mixed powder is produced. Here, a mixed powder obtained by mixing a zirconium oxide powder in which at least one of Y, Ce, and Dy is dissolved and a zinc oxide powder may be used. This zirconium oxide powder is obtained by a known method, for example, a coprecipitation method described in Haberko K., Res. Int. Htes Temp. Et Riefract + 14, 217-224. , 48 [7], 372-375., Sol-gel method described in Woodhead JL, Science of Ceramics, 10, 169-176., Reyen P, Advance in Ceramics, 3, 464. -475., Hydrothermal decomposition method described in Yoshimura M., Proceeding 5th Round Table Conference on Sintering, September 1981.

  (2) The mixed powder of any one of (1) is molded into a predetermined shape to produce a molded body. This molding step uses a known method, for example, a powder pressure molding method in which an organic binder such as polyvinyl alcohol (PVA) is added to mixed powder, mixed and granulated, and then filled into a mold and pressure is applied. Can do.

(3) The obtained molded body is sintered at a maximum temperature of 1250 to 1400 ° C. During this sintering, the compact is placed in a shielding jig for shielding the gas flowing around the compact and shielded, and the oxygen partial pressure in the firing furnace is 0.01 to 1 MPa, and the gas flows into the firing furnace. It is important to fire at a flow rate of 0.1 to 1 Nm ³ / min.

  Here, FIG. 2 shows an example of a state in which the molded body is housed in a shielding jig for obtaining the zirconium oxide sintered body 1 of the present invention. (A) is a perspective view which shows the state which put the molded object in the jig | tool for shielding and fractured | ruptured one part, (b) is sectional drawing in the A-A 'line of (a). In addition, when showing the same site | part in these, the same code | symbol is attached | subjected.

  The shielding jig 26 includes a lower plate 22a, a side plate 24, and an upper plate 22b. A plurality of molded bodies 20 are placed side by side on the lower plate 22a, and the side plate 24 and the upper plate 22b Surrounded. At this time, since the lower plate 22a, the side plate 24, and the upper plate 22b are in contact with each other, the gas does not easily flow into the shielding jig 26 from the outside. The material of the shielding jig 26 is preferably an alumina sintered body or a magnesium oxide sintered body having a melting point of 1600 ° C. or higher in order to suppress a chemical reaction between the molded body 20 and the shielding jig 26 during firing. It is. If the molded body can be accommodated, the side plate 24 and the upper plate 22b, and the side plate 24 and the lower plate 22a can be integrally manufactured.

In the zirconium oxide sintered body 1, ZnO decomposes from the vicinity of the surface of the sintered body and Zn gas and oxygen gas start to evaporate while being held at the maximum temperature of 1250 to 1400 ° C. during firing. When the molded body 20 is fired by using the jig 26 and setting the oxygen partial pressure in the firing furnace to 0.01 to 1 MPa and the flow rate of the gas flowing in the firing furnace to 0.1 to 1 Nm ³ / min, the inside of the shielding jig 26 It is difficult for gas from the outside to flow in, and during the holding at the maximum temperature, a large amount of ZnO is decomposed from the vicinity of the surface of the sintered body, and it is suppressed that Zn gas and oxygen gas evaporate. 2, the zirconium oxide sintered body 1 in which the semiconductive zinc oxide grain boundary layer 3 is continuous from the inside to the vicinity of the surface can be produced. At this time, for example, when the molded body 20 is simply arranged on the lower plate 22a without being stored in the shielding jig 26, ZnO is decomposed in a large amount from the vicinity of the surface of the sintered body so that Zn gas and oxygen gas Evaporates and the zinc oxide grain boundary layer 3 having semiconductivity disappears from the vicinity of the surface, so that the volume resistivity increases, resulting in a zirconium oxide sintered body 1 that is not semiconductive.

  The reason for this is that the decomposition and evaporation of zinc oxide that occurs during firing is accelerated the faster the flow of air around the compact 20, so if the compact 20 is not fired in the shielding jig 26, A large amount of zinc oxide decomposes and evaporates from the zinc oxide grain boundary layer 3 in the region, and the zinc oxide grain boundary layer 3 having semiconductivity is eliminated from the vicinity of the surface, and the volume resistivity of the obtained sintered body increases. This is probably because the zirconium oxide sintered body 1 is not semiconductive.

  In addition, when the oxygen partial pressure in the firing furnace at the highest temperature during firing is less than 0.01 MPa, zinc oxide is decomposed and evaporated in a large amount from the zinc oxide grain boundary layer 3 formed in the vicinity of the surface. The zinc oxide-based grain boundary layer 3 disappears, and as a result, the volume specific resistance value of the obtained sintered body increases, resulting in a zirconium oxide-based sintered body 1 that is not semiconductive.

  On the other hand, when it exceeds 1 MPa, Y, Ce, and Dy that exert the effect of semiconductivity in the zinc oxide grain boundary layer 3 during the holding at the maximum temperature are hardly dissolved. Y, Ce and Dy are all dissolved in the ZnO crystal, and as a result, although not clearly understood, there are those that transfer charges such as holes due to the generation of oxygen defects caused by the absence of oxygen in the crystal lattice of ZnO. Happens. However, when the oxygen partial pressure exceeds 1 MPa, the generation of oxygen vacancies is suppressed, so that it is difficult to generate a substance that transfers charges such as holes. It is considered that the fact that holes and the like are hardly generated also leads to the fact that Y, Ce and Dy are hardly dissolved in the ZnO crystal. Therefore, the volume specific resistance value of the obtained sintered body increases, and the semiconductive zirconium oxide sintered body 1 cannot be obtained.

If the flow rate of the gas flowing into the firing furnace is less than 0.1 Nm ³ / min, oxygen gas is not sufficiently supplied into the shielding jig 26 when the oxygen partial pressure is as low as 0.01 MPa or more and less than 0.05 MPa. Since the oxygen partial pressure in the shielding jig 26 is lower than 0.01 MPa, it is not semiconductive.

When the flow rate of the gas flowing into the firing furnace exceeds 1 Nm ³ / min, the flow velocity of the gas flowing through the firing furnace becomes very fast, and a large amount of gas flows from between the lower plate 22a and the side plate 24. As a result, a large amount of Zn gas evaporates from the sintered body in the shielding jig 26, and Zn disappears from the vicinity of the surface of the sintered body, so that it is not semiconductive.

  Next, after generating the zinc oxide grain boundary layer 3 by maintaining at the maximum temperature, the temperature is gradually decreased to 1150 ° C. while maintaining the oxygen partial pressure in the firing furnace at 0.01 to 1 MPa. Since the gas in the shielding jig 26 contracts during this temperature decrease, the gas gradually flows from the outside of the shielding jig 26 into the shielding jig 26 as the temperature decreases. When the pressure is 0.01 to 1 MPa, a very small amount of zinc oxide generated by the reaction of the Zn gas in the shielding jig 26 with the oxygen gas adheres to the surface of the sintered body. Further, this very small amount of adhered zinc oxide is integrally sintered with the zinc oxide grain boundary layer 3 in the vicinity of the surface, and a continuous zinc oxide grain boundary layer 3 is formed from the inside to the vicinity of the surface to form a semiconductive zirconium oxide. A quality sintered body 1 can be obtained. The thus formed zinc oxide grain boundary layer 3 has very few lattice defects, and becomes zinc oxide crystals (continuous zinc oxide grain boundary layer 3a) that are strongly sintered with each other.

  When the oxygen partial pressure during temperature reduction to 1150 ° C is less than 0.01 MPa, zinc oxide decomposes and evaporates from the sintered body even during the temperature decrease, so that semiconductive crystals disappear from the surface and the resulting zirconium oxide The sintered material 1 is not preferable because it is a non-semiconductive material having a large volume resistivity.

  Further, when the oxygen partial pressure during the temperature decrease to 1150 ° C. exceeds 1 MPa, immediately after the temperature decrease starts, the Zn gas in the gap in the shielding jig 26 reacts with the oxygen gas to generate zinc oxide. Since the produced zinc oxide becomes crystals and adheres to the surface of the sintered body in a large amount, the resulting zirconium oxide-based sintered body 1 has a higher Zn concentration near the surface than the inside. When this sintered body is exposed to an acidic aqueous solution or an alkaline aqueous solution, a large amount of zinc oxide crystals elute from the vicinity of the surface of the sintered body into the acidic aqueous solution or alkaline aqueous solution, and the eluted zinc oxide reprecipitates, resulting in many particles. There is a problem that occurs. Here, the zinc oxide crystals fixed on the surface of the sintered body are likely to elute. The crystals with a structure in which a large amount of zinc oxide generated on the surface of the sintered body is fixed and stacked when the temperature is lowered are crystals. It is considered that the lattice matching is very poor and the number of lattice defects between the two is so large that the chemical bonding force between the two becomes small, resulting in a decrease in corrosion resistance to acidic aqueous solutions and alkaline aqueous solutions. .

  Finally, when cooled from 1150 ° C. to room temperature, the zirconium oxide sintered body 1 of the present invention can be manufactured.

  Further, in this manufacturing method, by setting the lower limit value of the oxygen partial pressure to 0.05 MPa, when the Zn concentration inside the zirconium oxide sintered body 1 is 1, the ratio with the Zn concentration in the vicinity of the surface is A zirconium oxide-based sintered body 1 that is 0.8 or more can be produced. Accordingly, it is possible to obtain a zirconium oxide sintered body 1 that suppresses a decrease in surface resistance and has sufficient semiconductivity. The reason for this is considered to be that by setting the lower limit value of the oxygen partial pressure to 0.05 MPa, the amount of zinc oxide decomposed and evaporated from the zinc oxide grain boundary layer 3 in the vicinity of the surface is particularly reduced.

Furthermore, if the oxygen partial pressure is set to 0.05 to 1 MPa and the gas flow rate in the firing furnace is set to 0.1 to 1 Nm ³ / min, the temporal variation of the oxygen partial pressure in the firing furnace can be suppressed, so that the obtained firing When the Zn concentration in the bonded body is 1, the zirconium oxide sintered body 1 having a Zn concentration ratio in the vicinity of the surface of 0.8 or more can be produced.

  In this manufacturing method, since zinc oxide evaporates during firing, the amount of zinc oxide contained in the sintered body may be smaller than the content of Zn contained in the mixed powder. Can be produced by preliminarily compensating for the amount of zinc oxide decomposed and evaporated during firing in the mixed powder production process.

(1A) High-purity zirconium oxide (ZrO ₂ ) powder having an average particle size of 0.3 μm, yttrium oxide (Y ₂ O ₃ ) powder, cerium oxide (CeO ₂ ) powder, and dysprosium oxide (Dy ₂ O ₃ ) powder And zinc oxide (ZnO) powder, as shown in Table 1, ZrO ₂ is 52 to 89% by mass, at least one of Y ₂ O ₃ , CeO ₂ and Dy ₂ O ₃ or the total as shown in Table 1 Was mixed so as to be 1 to 12% by mass and ZnO was 10 to 40% by mass to prepare a mixed powder. In addition, the composition of Table 1 shows the composition of a sintered compact.

  (2A) To this mixed powder, 4 parts by mass of polyvinyl alcohol (PVA) as an organic binder was added to 100 parts by mass of the mixed powder, mixed and granulated to prepare a molding powder. The molding powder was filled in a mold and pressed at a molding pressure of 100 MPa to form a predetermined shape.

  (3A) The shielding jig 26 includes an alumina lower plate 22a (160 mm × 160 mm × 7 mm), an upper plate 22b (160 mm × 160 mm × 7 mm), and a side plate 24 (height 130 mm, outer shape 160 mm × 160 mm × thickness 7 mm). The upper plate 22b and the side plate 24 were joined to each other by applying a bonding glass paste between them and then heated to 1400 ° C. to join the upper plate 22b and the side plate 24. . The compact is placed in the shielding jig 26 having such a configuration, and fired at the maximum temperature of 1250 to 1400 ° C. at the oxygen partial pressure and gas flow rate shown in Table 1 to produce the zirconium oxide sintered body 1 of the present invention. did.

  (4A) Moreover, sample No. shown in Table 1 as a comparative example. Thus, a sintered body in which either the composition or the firing condition was outside the scope of the present invention was prepared.

  Next, evaluation was performed using these.

(A) Composition of sintered body The sintered body was pulverized, and the contents of Zr, Y, Ce, Dy, and Zn were measured by ICP emission spectroscopy, and ZrO ₂ , Y ₂ O ₃ , CeO ₂ , and Dy, respectively. Converted to ₂ O ₃ and ZnO. The compositions shown in Table 1 are values converted in this way.

(B) Fracture toughness value In accordance with the IF method described in JIS R 1607 (1995), a sintered body having a length of 40 mm, a width of 5 mm, and a thickness of 4 mm was mirror-polished to an arithmetic average height Ra of 0.05 μm. The test piece was measured. A diamond indentation terminal is pushed into the mirror surface, the indentation and cracks generated by this are observed, the fracture toughness value Kc (Pa · m ^1/2 ) is determined by the following equation, and the unit is MPa · m ^1/2 Converted into

Kc = (0.026E ^1/2 P ^1/2 α) / C ^3/2
Where E is the elastic modulus (Pa), P is the indentation load (N) of the indentation terminal, α is half the average diagonal length of the indentation (m), and C is the average length of cracks (cracks). Half (m).

  The elastic modulus E (Pa) was measured by an ultrasonic pulse method described in JIS R 1602 (1995). That is, an ultrasonic wave was applied to the sintered body and obtained by the following formula.

_{^{E = ρ (3V t 2 V}} l 2 -4V t 4) / (V l 2 -V t 2)
Here, ρ is the bulk density (kg / m ³ ) determined by the Archimedes method, V ₁ is the velocity of the longitudinal wave (m / s), and V _t is the velocity of the transverse wave (m / s).

(C) Bending strength In accordance with JIS R 1601 (1995), a sintered body was processed, the arithmetic average height was Ra 0.2 μm or less, length 36 mm × width 4 mm × thickness 3 mm, and C of 0.2 mm. Ten test pieces with a surface were prepared, a load was applied to the test piece using a load tester, the maximum load until breakage was measured, and the three-point bending strength was calculated by the following equation.

3-point bending strength σ ₃ (N / mm ² ) = 3PL / 2 wt ²
Here, P is the maximum load (N) when the test piece breaks, L is the distance between the lower fulcrums (mm), w is the width (mm) of the test piece, and t is the thickness (mm) of the test piece. .

(D) Ratio of Zn concentration in the vicinity of the surface to the concentration of internal Zn First, samples for analysis (sintered bodies) having different Zn concentration ratios were prepared as follows.

Analysis area for measuring and analyzing the inside of the sintered body obtained by polishing the zirconium oxide sintered body 1 0.5 mm from the surface and the vicinity of the surface on the observation screen of a scanning electron microscope (SEM) The intensity of Zn element was measured by detecting the wavelength of characteristic X-rays generated by electron beam irradiation on the surface with a wavelength dispersive X-ray microanalyzer (WDS). The measurement conditions at this time are an acceleration voltage of about 15 kV, a probe current of about 10 ⁻⁷ A, and an area of the analysis area of about 10 ⁶ μm ^2. And averaged. Then, assuming that the concentration of Zn in the inside is 1, the ratio of the concentration of Zn in the vicinity of the surface was obtained by dividing the Zn element strength in the vicinity of the surface by the Zn element strength in the interior.

(E) Electrical characteristics In accordance with JIS C 2141 (1992), an ultrasonic cleaning machine was used for each sintered body having a diameter of 62 mm and a thickness of 3 mm in a pH 5 hydrochloric acid aqueous solution and a pH 11 sodium hydroxide aqueous solution for 10 minutes each. After ultrasonic cleaning using (BRANSON DHA-1000 manufactured by Cleansonic), it was cleaned with pure water and dried to determine the surface resistivity and volume resistivity.

(F) Number of generated particles Particles contained in each of pH 5 hydrochloric acid aqueous solution and pH 11 sodium hydroxide aqueous solution used for ultrasonic cleaning were measured with a particle counter (KL-26 manufactured by Rion Co., Ltd.). . The number of particles shown in Table 1 is the total number of particles of hydrochloric acid aqueous solution and sodium hydroxide aqueous solution measured by a particle counter, and the surface area of the sintered body is determined using the number of particles and the surface area of the sintered body. It is a value converted to the number of particles emitted from 1 cm ² (number / cm ² ). In addition, the number of particles measured the number of particles having a particle size of 0.1 μm to less than 0.3 μm, 0.3 μm to less than 0.5 μm, 0.5 μm or more, and using these numbers and the surface area of the sintered body, The generation amount (particles / cm ² ) of particles released from the surface area of 1 cm ^{2 of the} sintered body was determined.

Table 1 shows the respective compositions, firing conditions, and evaluation results.

As is apparent from the results shown in Table 1, the sample within the scope of the present invention has a Zn concentration ratio in the vicinity of the surface of 0.75 to 0.98 when the Zn concentration inside the sintered body is 1, The Zn concentration near the surface of the bonded body was lower than the Zn concentration inside. Further, the fracture toughness value is 4 to 5, and the three-point bending strength is 700 to 930 MPa, which is a practically sufficient mechanical property, the surface resistivity is 10 ³ to 10 ⁹ Ω, and the volume resistivity value is 2 to 10 ^6. It showed Ω · m and semiconductivity. Further, no particles having a particle size of 0.3 μm or more were generated, and the number of particles having a particle size of 0.1 μm to less than 0.3 μm was as small as 10 particles / cm ² or less.

The characteristics of the comparative sample were as follows. Sample No. 1 containing 91% by mass of Zr in terms of ZrO ₂ and 7% by mass of Zn in terms of ZnO. No. 1 had a large surface resistivity and volume resistivity, and was not semiconductive. Sample No. containing 49 mass% of Zr in terms of ZrO ₂ 11 had smaller fracture toughness and bending strength. Sample No. with a total content of 0.5 mass% when the content of at least one of Y, Ce and Dy is converted to Y ₂ O ₃ , CeO ₂ and Dy ₂ O ₃ , respectively. No. 6 has a small fracture toughness value and bending strength, and a large amount of particles is generated. In No. 7, the fracture toughness value and bending strength were small. Sample No. 8 containing 8% by mass of Zn in terms of ZnO. No. 4 had large surface resistivity and volume resistivity, and did not have semiconductivity. Sample No. with a ZnO content of 42 mass% No. 10 had a small fracture toughness value and bending strength, and had a volume resistivity value of 1 × 10 ⁻³ Ω and became conductive. Sample No. without shielding jig In Nos. 13 and 15, Zn was not present in the vicinity of the surface of the sintered body, the surface resistivity and the volume resistivity were large, and they were not semiconductive. Sample No. fired with an oxygen partial pressure of 0 MPa and 0.002 MPa. In Nos. 16 and 17, Zn was not present in the vicinity of the surface of the sintered body, the surface resistivity and the volume specific resistance value were large, and it was not semiconductive. Sample No. fired at an oxygen partial pressure of 1.5 MPa and 2 MPa. In 22 and 23, the Zn concentration ratio was as large as 1.06 and 1.15, respectively, and very many particles were generated. Sample No. fired with a gas flow rate of 0.002 Nm ³ / min. In No. 24, Zn did not exist in the vicinity of the surface of the sintered body, the surface resistivity and the surface resistance value were high, and it did not have semiconductivity. Sample No. fired with a gas flow rate of 1.3 Nm ³ / min. No. 28 had high surface resistivity and surface resistance, and did not have semiconductivity.

  From the results of Examples and Comparative Examples, the samples of Comparative Examples were not preferred for use in supporting jigs due to any of semiconductivity, mechanical properties, and particle generation amount. On the other hand, in the sample of the present invention, the Zn concentration in the vicinity of the surface of the sintered body is lower than the Zn concentration inside, and has semiconductivity and sufficient mechanical properties in practical use. It can be seen that the number of particles generated from the sintered body is small when washed with an aqueous solution, and sufficient semiconductivity is maintained even after these washings are performed, making it suitable as a supporting jig.

It is a block diagram which shows the example of a structure of the crystal | crystallization of the zirconium oxide sintered compact of this invention. It is an example of the state which accommodated the molded object in the jig | tool for shielding for obtaining the zirconium oxide sintered body of this invention, (a) shows the state which accommodated the molded object in the jig for shielding and fractured | ruptured one part. It is a perspective view, (b) is sectional drawing in the AA 'line of (a).

Explanation of symbols

1: Zirconium oxide sintered body 2: Zirconium oxide crystal 3, 3a, 3b: Zinc oxide grain boundary layer
20: Molded body
22a: Lower plate
22b: Upper plate
24: Side plate
26: Shielding jig

Claims (2)

It consists of an oxide containing at least Zr, at least one of Y, Ce, and Dy as a metal element and Zn, and the Zr is 52 to 89% by mass in terms of ZrO ₂ , of the Y, Ce, and Dy In the zirconium oxide sintered body containing at least one of 1 to 12% by mass in terms of Y ₂ O ₃ , CeO ₂ and Dy ₂ O ₃ and 10 to 40% by mass of Zn in terms of ZnO, respectively, There are continuous zinc oxide grain boundary layers between the crystals, and the zinc oxide grain boundary layer has a Zn concentration in the range of the depth from the surface of the sintered body to the inner direction of 0.1 mm. A zirconium oxide sintered body characterized by being lower than the concentration of Zn inside. When the Zn concentration in the sintered body is 1, the Zn concentration ratio in the range of the depth from the surface of the sintered body to the internal direction to 0.1 mm is 0.8 or more. The zirconium oxide sintered body according to claim 1, wherein:

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