JP2003212652A - Zirconia sintered compact manufacturing method and zirconia sintered compact - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a zirconia sintered compact which is colored uniformly in black and consequently advantageous when foreign matter is inspected and has a dense structure or has a dense structure colored uniformly in black and to provide the zirconia sintered compact manufactured by this method. <P>SOLUTION: This method for manufacturing the zirconia sintered compact comprises a step to sinter the substance containing zirconia and the oxide of an element (except zirconium) of group IV in the periodic table in hydrogen- containing atmosphere, a nitrogen-containing atmosphere or a moisture- containing atmosphere. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a zirconia sintered body and a zirconia sintered body. More specifically, it is advantageous for foreign matter inspection because it is colored in a uniform black color and has a dense sintered body structure. Or a method of manufacturing a zirconia sintered body having a dense sintered body structure colored uniformly black.
And a zirconia sintered body manufactured by the manufacturing method thereof, which has a uniform black color and is dense.

[0002]

2. Description of the Related Art Bearings are used for hard disks in machine tools and computers. Balls used for bearings (hereinafter referred to as "bearing balls") are generally formed of metal such as bearing steel, but since greater wear resistance is required, the metal bearing balls Instead, ceramic bearing balls are used. In addition to manufacturing bearing balls from ceramics in this way, ceramics are used to form sliding parts in drive parts of semiconductor devices, sliding parts for automobiles such as tappets, etc. by utilizing the high temperature corrosion resistance of ceramics. There is.

Precise polishing is performed on various ceramic products, and the presence or absence of material defects such as foreign matter and pores or defects such as scratches, scratches and chips during polishing are inspected after the polishing. . This inspection may be performed by using a stereoscopic microscope, a metallographic microscope, or the like, but recently, in order to cope with mass production and cost reduction, it is often performed by an automatic appearance inspection machine or the like. In the automatic appearance inspection machine, an image is formed on the polished surface, and foreign matters on the polished surface and defective portions such as pores are identified by the color tone or the contrast of light and shade with the background portion.

The appearance and color tone of the ceramic sintered body are generally white or light gray. Moreover,
Defects such as pores and chips also show a bright color tone, so that it is difficult to provide a contrast between the defect and the background, and therefore, the accuracy of the identification by the automatic appearance inspection machine is not good. In particular, since the automatic visual inspection machine performs the defect inspection by the data processing based on the color difference and / or the brightness difference between the background and the defect, there is a limit to the improvement of the inspection accuracy. Therefore, according to JP-A-4-254471 or JP-A-4-254473, a sintered body is intentionally blacked by firing a molded body containing a carbon source or impregnating a porous body with carbon. Alternatively, there is disclosed a method of coloring in dark gray to reduce color unevenness of the sintered body. However, such a method has a problem in that the number of steps is increased in that it requires the use of a carbon source or an impregnation operation of carbon.

As described above, the quality of the ceramic product to be shipped can be improved by removing defective products by the automatic appearance inspection machine and improving the inspection accuracy.

On the other hand, the improvement of the quality of ceramic products can be achieved by preventing the production of defective products. For example, if it is possible to produce a dense ceramic sintered body that stabilizes the sintering of the ceramic and does not cause defects such as chipping, the number of defective products eliminated by the automatic visual inspection machine will decrease, and the quality will increase accordingly. High ceramic products should be obtained.

[0007] Thus, for the purpose of improving the quality of ceramic products, there is a demand for a simple method capable of sintering a ceramic sintered body having a high density and therefore a dense one.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a uniformly black zirconia sintered body. Another object of the present invention is to provide a method for producing a dense zirconia sintered body having a large density. Still another object of the present invention is to provide a method for producing a zirconia sintered body which has a high density and is dense and which is colored in a uniform black color, and a defective product can be easily found by an automatic visual inspection machine. To provide. Another object of this invention is to obtain a uniform black coloration,
It is to provide a zirconia sintered body having a dense structure.

[0009]

Means for solving the problems are as follows. (1) The inclusion of zirconia and an oxide of a Group 4 element (excluding zirconium) in the periodic table into hydrogen. A method for producing a zirconia sintered body, which comprises firing in an oxygen-free atmosphere containing (2)
A method for producing a zirconia sintered body, which comprises firing an inclusion of zirconia and an oxide of a Group 4 element (excluding zirconium) in the periodic table in an oxygen-free atmosphere containing nitrogen. And (3) zirconia sintering, characterized in that the inclusion of zirconia and an oxide of a Group 4 element (excluding zirconium) in the periodic table is fired in an oxygen-free atmosphere containing water. A method for producing a body, comprising: (4) primary calcination of a content of zirconia and an oxide of a Group 4 element (excluding zirconium) in the periodic table, and the resulting primary calcination product is further secondary calcinated. In doing so, it is a method for producing a zirconia sintered body, which comprises performing the secondary firing in an oxygen-free inert atmosphere, (5) The method for producing a zirconia sintered body according to (4) above. In front A method for producing a zirconia sintered body in which an oxygen-free inert atmosphere is an atmosphere containing argon gas, (6) In the method for producing a zirconia sintered body according to (4) or (5), the primary firing is performed. Is, (1) an oxygen-free atmosphere containing hydrogen, (2) an oxygen-free atmosphere containing nitrogen, or (3) is a method for producing a zirconia sintered body performed under an oxygen-free atmosphere containing water,
(7) A zirconia sintered body produced by the method according to any one of (1) to (6).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a zirconia sintered body according to the present invention is a method for producing a zirconia and an oxide of a Group 4 element (excluding zirconium) in the periodic table under a specific atmosphere. It is characterized by being fired at.

The periodic table means a periodic table recommended by IUPAC in 1990 ["Inorganic Chemistry Nomenclature-IUPA"].
C 1990 Recommendation- "G. J. LEIGH, translated and written by Kazuo Yamazaki, p. 43, 1st edition, 1st edition, published on March 26, 1993, Tokyo Kagaku Dojin]. ).

Examples of zirconia include zirconium oxide, stabilized zirconia and partially stabilized zirconia. Examples of the stabilized zirconia include zirconium oxide, CaO, MgO, CeO ₂ , or Y ₂ O.
Examples include so-called stabilized zirconia which forms a cubic crystal or a tetragonal crystal by solid-solubilizing a stabilizer such as ₃ . Also,
The partially stabilized zirconia is not particularly limited as long as it is a composition in which the stabilizer is not added so as to completely form a cubic solid solution. Further, as the partially stabilized zirconia, both precipitation type partially stabilized zirconia and dispersion type partially stabilized zirconia can be used.

Zirconia in the present invention is usually contained in an amount of 2% by mass as an unavoidable impurity or for suppressing transformation.
Aluminum oxide, for example, is contained as an additive added at the following ratio.

The zirconia used in the present invention is preferably a powder having a particle size of 1 μm or less, preferably 0.7 μm or less, more preferably 0.5 to 0.2 μm.

Examples of elements belonging to Group 4 of the periodic table include Ti and Hf. Therefore, examples of the oxide of the Group 4 element contained in this zirconia sintered body include titanium oxide (hereinafter sometimes referred to as titania) and hafnium oxide. The titanium oxide may be any of rutile type, anatase type and brookite type titanium oxides, and may be titanium oxides such as TiO ₂ , Ti ₂ O ₃ and TiO ₂ . As the titanium oxide in the present invention, Ti _x O _y (where x is 1 to 3,
y is 1 to 5 and is an X-ray photoelectron spectrometer (X-ray Phot
oelectron Spectrometer, abbreviation XPS. ) Is determined by. Further, the titanium oxide represented by the formula () is more preferable.

Oxides of Group 4 elements (excluding zirconium), especially titanium oxide, have a particle size of 2 μm.
The following is preferable. When using a powder coarser than these, it is recommended to further pulverize the zirconia powder or the oxide powder of the Group 4 element (excluding zirconium) in advance.

The content ratio of the zirconia in the inclusion is not particularly limited, but when attention is paid to the characteristics of the obtained zirconia sintered body, zirconia and an oxide of a Group 4 element (excluding zirconium) are included. It is usually 10 to 40% by mass with respect to the total. Zirconia content is 4
If it is more than 0% by mass, there may occur a problem that conductivity is not exhibited, and the content of zirconia is 1
If it is less than 0% by mass, the strength of the zirconia sintered body may not be improved.

The inclusions to be fired may be a mixture of the zirconia powder and the Group 4 element oxide powder, or may be a slurry. The zirconia powder and the Group 4 element oxide powder are usually about 700 to 1100 ° C., preferably 800 to 1000.
Although it is used as a calcined powder by heating at about ℃, it is not limited to this, it is also possible to use a starting raw material powder not calcined. In the case of calcination, in addition to calcination of each starting material, particle size adjustment may be performed by calcination collectively after mixing.

The inclusion may contain a sintering aid. As the sintering aid, generally used aids can be adopted without limitation as long as the object of the present invention is not impaired, and rare earth element compounds such as yttrium oxide and metal oxides such as magnesium oxide are preferable. Is.
The amount of the sintering aid added is not particularly limited, but it is usually 15 mol% or less based on the whole amount.

As a specific atmosphere for sintering, (1) an oxygen-free atmosphere containing hydrogen (hereinafter sometimes referred to as a hydrogen-containing oxygen-free atmosphere), (2) an oxygen-free atmosphere containing nitrogen ( Hereinafter, it may be referred to as a nitrogen-containing oxygen-free atmosphere.), And (3) an oxygen-free atmosphere containing water, that is, water vapor (hereinafter sometimes referred to as a water-vapor-containing oxygen-free atmosphere). it can.
Here, the term "oxygen-free atmosphere" should be understood to mean an atmosphere containing substantially no oxygen. What is common to these three kinds of atmospheres is that they do not substantially contain oxygen. Therefore,
Hereinafter, these three kinds of atmospheres may be collectively referred to as an oxygen-free atmosphere. This oxygen-free atmosphere can be realized by evacuating the space for sintering, for example, the internal space of the sintering furnace by an appropriate exhaust means, and introducing hydrogen, nitrogen, steam or the like as needed. The term "atmosphere" means a gas that surrounds the body to be sintered.

(1) The hydrogen-containing oxygen-free atmosphere is hydrogen 1
The gas may be 00%, or may be a hydrogen-containing mixed gas containing hydrogen and another gas. When the above-mentioned material is fired in a hydrogen-containing oxygen-free atmosphere, the surface of the obtained zirconia sintered body becomes black, although the reason is not clear. The black color of the zirconia sintered body can be determined by visual comparison of the appearance color of the polished surface of the zirconia sintered body with a standard color chart prepared according to JIS-Z8721. That is, it is possible to determine that the zirconia sintered body is black because the brightness is 1 to 3.5.

When the hydrogen-containing oxygen-free atmosphere is a hydrogen-containing mixed gas, the hydrogen content in the hydrogen-containing mixed gas is at least 25% (25% or more), preferably at least 50% (50% or more). ). When the content of hydrogen in the hydrogen-containing mixed gas is less than the lower limit value, the color of the obtained zirconia sintered body may not be black.

Examples of the other gas contained in the hydrogen-containing mixed gas include an inert gas such as argon gas, steam gas and nitrogen gas.

When the other gas is nitrogen gas, the hydrogen-containing mixed gas also becomes a nitrogen-containing oxygen-free atmosphere, and when the other gas is steam gas, the hydrogen-containing mixed gas does not contain water vapor. It also becomes an oxygen atmosphere.

(2) The oxygen-free atmosphere containing nitrogen contains 10% nitrogen.
It may be 0% gas, or may be a nitrogen-containing mixed gas containing nitrogen and another gas. When the content is fired in a nitrogen-containing oxygen-free atmosphere, the density of the zirconia sintered body is improved and the zirconia sintered body becomes dense.

Examples of the other gas contained in the nitrogen-containing mixed gas include an inert gas such as argon gas, steam gas and nitrogen gas.

When the other gas is hydrogen gas, the nitrogen-containing mixed gas becomes a hydrogen-containing oxygen-free atmosphere, and when the other gas is water vapor gas, the nitrogen-containing mixed gas is not containing water vapor. It also becomes an oxygen atmosphere.

(3) The water vapor-containing oxygen-free atmosphere is a gas atmosphere that contains water vapor but does not contain oxygen, and contains hydrogen gas, nitrogen gas, and other gases such as an inert gas such as argon gas. This water vapor-containing oxygen-free atmosphere is obtained by introducing a mixed gas containing other gas such as hydrogen gas, nitrogen gas and / or argon gas into water maintained at 20 to 70 ° C. and passing through the water. You can
When the contained material is fired under an oxygen-free atmosphere containing water vapor,
The density of the obtained fired product is improved, and a dense zirconia fired product is obtained.

In the method for producing a zirconia sintered body according to the present invention, the inclusion is fired in the specific atmosphere.

The firing operation may be performed in a single stage or in a two-stage firing process including a primary firing and a secondary firing.

The firing temperature in the case of single-stage firing is usually 1,300 to 1,700 ° C., preferably 1,30.
It is 0-1400 degreeC. The pressure in the specific atmosphere during firing is usually 1 to 10 atm, preferably 1 to 10 atm.
2 atm.

When the two-stage firing is performed to obtain a black zirconia sintered body, it is important to select the atmosphere. That is, (a) when selecting a hydrogen-containing oxygen-free atmosphere in the primary firing, the atmosphere in the secondary firing is not particularly limited, and (b) when selecting an oxygen-free inert atmosphere as the atmosphere in the secondary firing, The atmosphere in the primary firing is not particularly limited.

Furthermore, if a hydrogen-containing oxygen-free atmosphere is selected as the primary firing atmosphere and / or an oxygen-free inert atmosphere, especially an argon gas-containing atmosphere is selected as the secondary firing atmosphere, black zirconia is selected. A sintered body can be obtained. When an oxygen-free inert atmosphere is selected as the secondary firing atmosphere and a nitrogen-containing oxygen-free atmosphere or an oxygen-free atmosphere containing water is selected as the primary firing atmosphere, a black and dense zirconia sintered body is obtained. Can be obtained. The inert atmosphere is a gas atmosphere that does not react with zirconia, and nitrogen gas may react with zirconia to produce zirconia nitride, so the inert atmosphere does not contain nitrogen.

The pressure of the atmosphere in the primary firing is usually 1
-10 atm, the firing temperature is usually 1,300-1,
It is 700 ° C.

Whichever atmosphere is used, when performing the two-stage firing, the primary firing is 7 even if the ratio of the relative density to the theoretical density of the sintered body after the primary firing is small.
8% (78% or more), preferably at least 90%
(90% or more) is desirable. When the ratio of the relative density to the theoretical density of the sintered body after the primary firing is less than 78%, many defects such as pores tend to remain after the secondary firing. The secondary calcination is performed in an oxygen-free inert atmosphere containing no nitrogen, for example, with argon containing 10
~ 2,000 atm, non-oxidizing atmosphere, 1,400 ~
It can be performed at 1,700 ° C. If the pressure during firing is less than 10 atm, a large amount of pores may remain, and even if the pressure exceeds 2,000 atm, the technical effect corresponding to that may not be developed, which is uneconomical. If the firing temperature is less than 1,300 ° C., defects such as pores and scratches cannot be eliminated and the strength may be insufficient. When the two-step sintering is performed, a zirconia sintered body having a higher density and a higher density than that obtained by the single-step sintering can be obtained.

According to the method of the present invention, it is possible to obtain a uniformly black zirconia sintered body by selecting the firing atmosphere, and to obtain a dense and high-density zirconia sintered body. In addition, it is possible to obtain a zirconia sintered body which is uniformly black and is dense and has a high density.

Furthermore, since zirconia and an oxide of a Group 4 element are used as raw materials, according to the method of the present invention, the hardness and toughness are large, and the coefficient of thermal expansion is smaller than that of a sintered body of zirconia alone. The zirconia sintered body which has is obtained.

What is specially noted in the present invention is that when zirconia, particularly stabilized or partially stabilized zirconia and titanium oxide are blended and sintered by the method of the present invention, the toughness is improved and the electrical discharge machinability is improved. It is possible to obtain a zirconia sintered body which is provided with electric conductivity exhibiting an antistatic function and which has a coefficient of thermal expansion closer to that of metal than that of silicon nitride.

In addition, it is extremely important that the zirconia sintered body according to the present invention exhibits conductivity by containing titanium oxide. This is because conventionally, carbides and nitrides such as titanium, tungsten, molybdenum, etc. have been added as conductivity-imparting agents to impart conductivity to the zirconia sintered body containing zirconium as the main component. This is because the. Moreover, since these carbides and nitrides exist in the form of particles in the sintered structure, the difference in hardness from the zirconia particles causes the sintered body to be made into a true sphere when finished into a bearing ball. It was difficult to obtain accuracy.

However, in the zirconia sintered body according to the present invention, the titanium oxide selected as an oxide of the Group 4 element as a raw material is not contained as a stabilizer of zirconium but is provided with conductivity. It is contained as an agent and actually imparts conductivity to the zirconia sintered body. In addition, this zirconia sintered body can sufficiently obtain the precision when performing a precise surface finish. Therefore, where the titanium oxide is contained, the zirconia sintered body according to the present invention is excellent in antistatic property because it has conductivity, and is a material capable of electrical discharge machining, which is also a material with good processing accuracy. Become.

When the oxide of the Group 4 element in the zirconia sintered body according to the present invention is hafnium oxide, the hafnium oxide is already contained in the zirconia in an inseparable state. Therefore, in the method according to the present invention, hafnium oxide can be added to and mixed with zirconia containing hafnium oxide as an unavoidable inclusion.

In the zirconia sintered body according to the present invention, the content of the oxide of the Group 4 element of the periodic table (excluding zirconium) with respect to the zirconia sintered body is usually 10 to 10.
It is 40% by mass, preferably 20 to 30% by mass.

In this zirconia sintered body, the oxide of the Group 4 element other than zirconium exists as particles or in the grain boundary crystal phase. However, since titanium oxide is nitrided when sintering is performed in a nitrogen-containing oxygen-free atmosphere, in the zirconia sintered body according to the present invention, titanium nitride produced by nitriding titanium oxide is the surface of the zirconia sintered body. It exists in the vicinity and the concentration of titanium nitride tends to decrease from the vicinity of the surface toward the inside.

The zirconia sintered body according to the present invention has a small coefficient of thermal expansion of 6.5 × 10 ⁻⁶ / ° C.,
It is preferably at least 7.0 × 10 ⁻⁶ / ° C. Since the coefficient of thermal expansion of this zirconia sintered body is smaller than the coefficient of thermal expansion of zirconia alone, it can be used as a member used in an environment exposed to high temperature, such as a high pressure bearing member, a sliding member such as a bearing ball, or the like. When the sintered body is applied, it can be a member capable of stable and highly reliable rotary motion or reciprocal motion.

This coefficient of thermal expansion can be measured by the push rod differential method. The measurement atmosphere is the atmosphere. The push rod differential method is a method of determining the coefficient of thermal expansion of a sample by comparing the thermal expansion of a standard quartz sample with the thermal expansion of a sample. The measurement can be performed by a linear expansion coefficient test method by plastic thermomechanical analysis, which is based on JIS-K-7179 (1991). The thermal expansion coefficient of the zirconia sintered body according to the present invention can be adjusted by changing the amount of TiO ₂ .

The zirconia sintered body according to the present invention has a hardness of 1,250, and preferably 950 to 1,200 even if the Vickers hardness is large. This Vickers hardness is
It can be measured according to HV20 of JIS R1610 (1991).

The zirconia sintered body according to the present invention is ^{4MPam 0.5} with small its toughness, preferably 4.5MPam ^0.5 be small, more preferably from 4~10MPam ^0.5. This toughness is JIS
It can be determined according to the IF method of R1607 (1990). The toughness of the zirconia sintered body can be adjusted by adjusting TiO ₂ and the firing temperature.

The zirconia sintered body according to the present invention has an electric resistance value of at most 10 ⁸ Ω · cm, preferably at most 10 ³ Ω · cm. This electric resistance value is
A test piece having a cross-sectional area of 0.3 cm (A) in length and 0.4 cm (B) in width and 1.7 cm (L) in length and having gold vapor-deposited surfaces on both end surfaces was measured by a tester. The value is calculated by A × B × R / L. The electric resistance value of the zirconia sintered body according to the present invention can be adjusted by changing the compounding amount of the oxide of the Group 4 element and the firing conditions.

Since the zirconia sintered body according to the present invention has the above hardness, toughness and electric resistance value, it has a lower coefficient of thermal expansion than that of zirconia itself, and thus is suitably formed into, for example, a bearing ball. be able to.

The bearing ball formed of this zirconia sintered body does not cause problems due to electrostatic charging when used in electronic equipment such as hard disk drives.

Generally, if the rotary bearing member and / or the ball receiving portion constituting the bearing is formed of bearing steel such as SUJ2 defined in JIS G 4805, reliable high speed rotation can be realized. You can Zirconia itself has a linear expansion coefficient similar to that of bearing steel. For example, when a motor device is rotated at a high speed, the sliding heats the bearing itself to a high temperature. At that time, if the difference between the coefficient of linear expansion of the bearing ball and the coefficient of linear expansion of the material forming the rotary shaft member or the ball receiving portion is too large, thermal strain (asynchronous vibration) occurs, resulting in reliable and stable operation. It becomes difficult to achieve high-speed rotation. Therefore, by using a bearing ball made of a zirconia sintered body containing zirconia and titanium oxide having a linear expansion coefficient similar to that of bearing steel as in the present invention, adverse effects due to thermal strain can be suppressed.

As a device having a motor equipped with a bearing having a bearing ball made of a zirconia sintered body according to the present invention, for example, a magnetic recording device equipped with a hard disk drive, an optical disk device, or a DV device.
D, various kinds of equipment such as various game machines accompanied by rotational drive, and general motor equipment of machine tools such as lathe processing machines.

Since the zirconia sintered body according to the present invention has an electric resistance value within the above range, it is less likely to be charged, and electric discharge machining is possible. Since this zirconia sintered body is difficult to be charged, for example, when manufacturing a bearing ball with this zirconia sintered body, a bearing ball in the middle of manufacturing due to charging is clogged during transportation, does not cause adhesion to the device, etc. Manufacturing with smooth handling can be realized. Further, since this zirconia sintered body is capable of electric discharge machining, for example, the inner wall surface of a cylindrical shape can be easily and accurately cut by electric discharge machining.

The zirconia sintered body according to the present invention can be formed into various wear resistant members, for example. In particular, since this zirconia sintered body has conductivity by containing an oxide of a Group 4 element (excluding zirconium), electric discharge machining can be suitably performed. That is, by performing electric discharge machining, this zirconia sintered body can be formed into wear resistant members having various shapes.

The general contents of the electric discharge machining technology are described in "(New Edition) Mechanical Engineering Handbook B2 Machining amount / machinery" (1998).
Issued on 11th April, 2010, released by Maruzen Co., Ltd.) B2-
By the explanation on page 152 or the explanation on page 5-99 of "Mechanical Engineering Pocketbook" (published by 20th edition, 20th edition, June 20, 1982). Can be understood. According to the electric discharge machining, the work piece is finished with high machining accuracy. That is,
Electric discharge machining is suitable for precision machining. Since the zirconia sintered body according to the present invention has conductivity, it can be processed into a precision machined member by electric discharge machining.

For example, an optical connector member such as a ferrule can be cited as a precision processed member using the zirconia sintered body according to the present invention. Specific examples of ferrules are described in JP 2000-147320 A, JP 11-52178 A, and the like.
FIG. 1 shows an optical connector member using a ferrule.
In FIG. 1, 32 is an optical connector member, 33 is a ferrule, 34 is a loading hole into which an optical fiber 36 is loaded, and 35 is a back body.

For example, "Dictionary of Science and Engineering" (March 2, 1996)
As described on page 1263 of the first edition issued on the 8th, 1st edition, published by Nikkan Kogyo Shimbun Co., Ltd., the ferrule is used as a base for a connecting portion of an optical fiber. In order to prevent gain reduction due to erosion of the optical fiber connection part, dimensional error of the ferrule and the matching accuracy (concentricity) of the center of the inner and outer diameters are important. Therefore, careful processing is required for ferrule processing. become. Therefore, as shown in FIG. 2, the zirconia sintered body according to the present invention can be accurately and inexpensively manufactured into a ferrule by, for example, wire-cut electric discharge machining. In FIG. 2, reference numeral 30 is a wire, and 31 is a zirconia sintered body which is a workpiece to be processed into a ferrule.

The zirconia sintered body according to the present invention can be used as a bearing ball. The bearing ball formed of the zirconia sintered body according to the present invention has excellent wear resistance, that is, the bearing function is maintained for a long period of time, and the coefficient of thermal expansion is large. Therefore, the bearing function is lost due to the heat generated by high-speed rotation. There is nothing to do. Further, since this zirconia sintered body is excellent in antistatic property, it is possible to carry out smooth continuous production without being charged with static electricity in the manufacturing process of the ball bearing to cause clogging on the conveying path.

[0059]

EXAMPLES Examples of the present invention will be shown below.

Example 1, Comparative Example 1 Y ₂ O ₃ -containing partially stabilized zirconia powder (Daiichi Rare Element Chemical Industry Co., Ltd.)
Manufactured, product name: HSY) 70% by mass, and titanium oxide (manufactured by Toho Titanium Co., product name: high-purity titanium) based on the total of partially stabilized zirconia and titanium oxide 3
0% by mass and pure water mixed in a ratio of 1: 2 (mass basis) with respect to the total of partially stabilized zirconia and titanium oxide were put into a resin pot together with cobblestones, and wet-mixed for 16 hours. Then, the obtained slurry was cast in a plastic container and heated and dried at 60 ° C. for 10 hours, and the obtained solid material was crushed to produce a base powder for molding. Further, the base powder for molding could also be manufactured by loading the mixture into an attritor blender, performing wet mixing for 5 hours, and drying with a fluid-type dryer. This molding material powder is the inclusion in the present invention.

This molding material powder was added to 14.71 × 10 ⁴
A sample was prepared by press molding at a pressure of kPa (1.5 ton / cm ² converted to SI unit). This sample is shown in Table 1.
In the firing atmosphere shown in Table 1, firing was performed at the firing temperature shown in Table 1, and the density was measured. Table 1 shows the firing conditions and the density of the zirconia sintered body.

In Table 1, "H ₂ " is shown in the column of atmospheric gas and "Dry" in the column of water vapor atmosphere.
"H2" and "dew point 40 ° C" mean that an atmosphere of dry hydrogen gas is 100%. Similarly, "H ₂ " and "dew point 40 ° C" mean that a gas of 100% dry hydrogen gas passes through water at 40 ° C. It is a hydrogen-containing oxygen-free atmosphere containing water vapor after being allowed to be, “3H ₂ + N ₂ ”, and “dry” means that hydrogen gas and nitrogen gas have a volume ratio of 3: 1 (standard state). The atmosphere of mixed and dried gas is “3H ₂ + N ₂ ”, and “dew point 20 ° C.”, “dew point 40 ° C.” or “dew point 70 ° C.” means hydrogen gas and nitrogen gas. Is a water vapor-containing oxygen-free atmosphere obtained by passing a mixed gas in which 3 and 3 are mixed at a ratio of 3: 1 by volume (standard state) through water maintained at 20 ° C., 40 ° C. or 70 ° C. There a ₂ + _{N 2} ", the term" dew point 40 ° C. "is hydrogen The nitrogen gas is 1: water vapor-containing oxygen-free atmosphere obtained by the mixed gas mixture is passed through the in-water maintained at 40 ° C. at a rate of 1 volume% (standard conditions). The term "atmosphere" means that the sintering was performed in the atmosphere.

The blanking of the secondary firing atmosphere means that only the primary firing is performed without the secondary firing. In the column of the density of the zirconia sintered body, the density of the zirconia sintered body after the secondary firing is enclosed by ().

The color of the zirconia sintered body was judged by visually comparing the appearance color of the polished surface of the zirconia sintered body with a standard color chart prepared in accordance with JIS-Z8721.

Comparative Example 1 is an example of sintering in air as a firing atmosphere.

[0066]

[Table 1]

As is clear from the results shown in Table 1, the zirconia sintered body obtained by performing the primary firing in the air atmosphere was white, but the zirconia sintered in the hydrogen-containing oxygen-free atmosphere was obtained. The sintered body had a uniform black color. When the secondary firing is performed in an Ar atmosphere, it becomes black even if the primary firing is performed in the air. However, conductivity did not develop.

(Examples 2 to 9) Y ₂ O ₃ -containing partially stabilized zirconia powder (manufactured by Daiichi Rare Element Chemical Industry Co., Ltd., product name: HSY) and partially stabilized zirconia were added. Titanium oxide having a blending ratio shown in Table 1 (manufactured by Toho Titanium Co., Ltd., product name: high-purity titanium) and 1: 2 with respect to the total of partially stabilized zirconia and titanium oxide.
Pure water mixed in the ratio (mass standard) is put into a resin pot together with cobblestones, wet-mixed for 16 hours, and the obtained slurry is cast in a plastic container and cast at 60 ° C.
The resulting solid is pulverized, then loaded into an attritor blender, wet-mixed for 5 hours, and dried in a fluid-type drier to form a molding base powder. Obtained.

This molding powder was made into 14.71 × 10 ⁴
A sample required for the following test was prepared by press molding under a pressure of kPa (1.5 ton / cm ² converted to SI unit). Each sample was fired in a 3H ₂ + N ₂ atmosphere at 1400 ° C. as a primary firing and in an argon atmosphere at 1500 atm as a secondary firing and at 1450 ° C., and the following evaluation test was performed on the obtained zirconia sintered body. went. The results of the evaluation test are shown in Table 2.

<Vickers hardness> JIS R1610
Load 19.61 according to the method specified in (1991)
Vickers hardness was determined by N.

<Toughness> JIS R1607 (1990)
The toughness value was measured according to the IF method defined in 1.

<Resistance Value> The resistance value was measured by a tester (manufactured by Takedariken, model number: TR6824).

<Thermal Expansion Coefficient> The thermal expansion coefficient was determined by comparing the thermal expansion of the standard quartz sample with that of the sample by the push rod differential method. The measurement atmosphere is the atmosphere.

(Comparative Example 2) A molding base powder was obtained in the same manner as in Example 2 except that the titanium oxide used in the above-mentioned Example 2 was not mixed, and this molding base powder was used to carry out the above-mentioned procedure. Samples necessary for conducting the same test as the example were prepared. The same evaluation test as in Example 2 was performed. The results of the evaluation test are shown in Table 2.

[0075]

[Table 2]

Example 10 A molding base powder composed of zirconia and titania having the composition of Example 5 was prepared in the same manner as in Example 2. By rolling granulation using this molding powder, 40 kg of spherical moldings having a diameter of about 2 mm were manufactured in total. This spherical compact was subjected to primary firing in a mixed gas atmosphere of hydrogen and nitrogen for 1
Baking is performed under the conditions of atmospheric pressure and 1,360 ° C., and then as secondary firing, under an argon atmosphere, at 1,500 atmospheric pressure and 1,4
It was fired under the condition of 50 ° C. After firing, the surface of the ball
The sphericity is 0.05 μm and the arithmetic mean roughness is 0.002 μm.
It was precisely polished so that The resulting balls had an average diameter of 1.5875 × 10 ⁻³ m (1/16 inch).
During this time, the obtained balls were free of electrostatic charge and could be handled smoothly.

When a large number of balls were circulated in a gutter inclined at about 30 degrees and dropped into a polypropylene container, static electricity was not applied and the balls did not get stuck on the way, and the balls on the inner wall of the container were not statically charged. It didn't adhere.

Comparative Example 3 A molding base powder made of zirconia in Comparative Example 2 was prepared in the same manner as in Example 2. A spherical compact having a diameter of about 2 mm was produced by rolling granulation using this molding powder. This spherical molded body was fired in the same manner as in Example 8 to obtain balls.
The ball after firing was precision-polished on the surface so that the sphericity was 0.08 μm and the arithmetic average roughness was 0.012 μm. During this time, the obtained balls were electrostatically charged and scattered, and smooth handling could not be performed. Also, when a large number of balls were circulated in a gutter inclined at about 30 degrees and dropped into a polypropylene container, they were charged with static electricity and the balls got stuck in the gutter in the middle, and the balls adhered to the inner wall of the container with static electricity. did.

[0079]

According to the present invention, it is possible to provide a method for producing a uniformly black zirconia sintered body. According to the present invention, it is possible to provide a method for producing a dense zirconia sintered body having a large density.
According to the present invention, it is possible to provide a method for producing a zirconia sintered body which has a high density and is dense, is colored in a uniform black color, and can easily detect a defective product by an automatic visual inspection machine. it can. According to this invention, it is intended to provide a zirconia sintered body which is colored in a uniform black color and has a dense structure.

Furthermore, it is possible to provide a method for producing a zirconia sintered body which is colored in a uniform black color, has excellent balance of hardness and toughness, has conductivity, and has a small coefficient of thermal expansion. The present invention can also provide a dense zirconia sintered body which has excellent antistatic properties, is easy to perform electric discharge machining, has a well-balanced hardness and toughness, is colored in black, and is colored in black. According to the present invention, it is possible to provide a zirconia sintered body that is not easily broken even if it is exposed to high-speed motion, and that does not easily occur in dimensional accuracy.

According to the present invention, charging does not occur in the middle of the conveying path due to electrification in the manufacturing process, and the surface can be easily finished to a precise surface by electric discharge machining, which has excellent wear resistance and long life. A zirconia sintered body suitable for an abradable member, an optical connector member, and a bearing ball can be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing an example of an optical connector member.

FIG. 2 is a schematic explanatory view showing a ferrule for producing a zirconia sintered body according to the present invention by wire cut electric discharge machining.

[Explanation of symbols]

32 ... Optical connector member, 33 ... Ferrule, 3
4 ... charging hole, 35 ... back body, 36 ...
Optical fibers 36, 30 ... Wires, 31 ... Sintered zirconia,

Claims (7)

[Claims] 1. Zirconia sintering, characterized in that the inclusion of zirconia and an oxide of a Group 4 element (excluding zirconium) in the periodic table is fired in an oxygen-free atmosphere containing hydrogen. Body manufacturing method. 2. Zirconia sintering, characterized in that an inclusion of zirconia and an oxide of a Group 4 element (excluding zirconium) in the periodic table is fired in an oxygen-free atmosphere containing nitrogen. Body manufacturing method. 3. Zirconia sintering, characterized in that an inclusion of zirconia and an oxide of a Group 4 element in the periodic table (excluding zirconium) is fired in an oxygen-free atmosphere containing water. Body manufacturing method. 4. A material containing zirconia and an oxide of a Group 4 element (excluding zirconium) in the periodic table is subjected to primary firing, and the obtained primary fired material is further subjected to secondary firing. A method for producing a zirconia sintered body, which comprises performing the secondary firing in an inert atmosphere of inclusion. 5. Oxygen is added to the material obtained by primary firing of a material containing zirconia and an oxide of a Group 4 element (excluding zirconium) in the periodic table, and further subjecting the obtained primary fired material to secondary firing. The method for producing a zirconia sintered body according to claim 4, wherein the inert atmosphere containing no gas is an atmosphere containing argon gas. 6. The method according to claim 1, wherein the primary firing is performed under (1) an oxygen-free atmosphere containing hydrogen, (2) an oxygen-free atmosphere containing nitrogen, or (3) an oxygen-free atmosphere containing water. Item 6. A method for producing a zirconia sintered body according to item 4 or 5. 7. A zirconia sintered body produced by the method according to any one of claims 1 to 6.