JP2003261376A - Zirconia sintered compact and method of producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductive zirconia sintered compact capable of releasing static electricity at an appropriate rate without significantly lowering mechanical characteristics of zirconia. <P>SOLUTION: The zirconia sintered compact contains 80 to 90 wt.% ZrO<SB>2</SB>including a stabilizer and at least 5 to 20 wt.% TiO<SB>2</SB>as an electroconductivity imparting agent, and has a specific volume resistivity of 10<SP>6</SP>to 10<SP>10</SP>Ω×cm. The semiconducting zirconia sintered compact having a specific volume resistivity of 10<SP>6</SP>to 10<SP>10</SP>Ω×cm is formed by incorporating 5 to 20 wt.% TiO<SB>2</SB>as an electroconductivity imparting agent into 80 to 90 wt.% ZrO<SB>2</SB>including the stabilizer, then subjecting the resulting mixture to oxidative firing, and further subjecting to reductive firing under an Ar atmosphere of normal pressure or a high pressure using HIP. <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 zirconia sintered body having semiconductivity while maintaining high strength. Specifically, it is used in the manufacturing process of semiconductor devices, magnetic heads, electronic parts and the like. It is suitable for applications requiring static electricity removal action such as jigs and tools, tape guides, and separating claws used in image forming apparatuses.

[0002]

2. Description of the Related Art Conventionally, a ceramic sintered body containing alumina, zirconia, silicon nitride, silicon carbide, etc. as a main component, which has been used as a material for structural parts, has high strength and high hardness as well as heat resistance and corrosion resistance. The zirconia sintered body is used in various fields because of its excellent heat resistance. However, the zirconia sintered body is used in applications where particularly excellent mechanical strength and sliding characteristics are required.

By the way, since the zirconia sintered body is a highly insulating material, a carrier arm used in a semiconductor manufacturing apparatus or the like, a wafer holding tweezers, a separation claw used in an image forming apparatus such as a printer, and a magnetic material. For use in applications where static electricity removal is required, such as tape guides used to convey and guide tape-shaped bodies such as tapes, drive carriers for taping packaging equipment for electronic components, etc. Set the volume resistivity to "1.
0 ⁶ to 10 ¹⁰ Ω · cm ”, and therefore,
Attempts have been made to reduce the resistance value by incorporating a conductivity-imparting agent into the zirconia sintered body.

For example, in Japanese Unexamined Patent Publication (Kokai) No. 10-297968, ZrO ₂ stabilized with Y ₂ O ₃ , MgO, CaO, CeO or the like is used as a main component, and a heavy metal oxide as a conductivity-imparting agent is added to Fe. , Co, Ni, and Cr oxides are contained, and a semiconductive zirconia sintered body having a volume resistivity of 10 ⁵ to 10 ⁹ Ω · cm is disclosed.

[0005]

The above-mentioned semiconductive zirconia sintered body is a heavy metal oxide (F) as a conductivity-imparting agent.
(e, Co, Co, Cr oxides) is used, there is a possibility that heavy metal oxides, which are problematic as impurities, may mix into manufacturing equipment and jigs and tools related to the manufacture of semiconductors and electronic parts. It was

An object of the present invention is Ti, which is a light metal oxide.
O ₂ is used to eliminate the influence of the problematic contamination of heavy metal impurities on manufacturing equipment and jigs and tools related to the manufacture of semiconductors and electronic parts, and to greatly reduce the mechanical properties of the zirconia sintered body. The present invention is to provide a zirconia sintered body capable of releasing static electricity at an appropriate speed without causing any damage.

[0007]

In view of the above problems, the present invention contains at least 80 to 95% by weight of ZrO ₂ containing a stabilizer and 5 to 20% by weight of TiO ₂ as a conductivity-imparting agent. Contains and has a volume resistivity of 10 ⁶ to 10 ¹⁰
The zirconia sintered body is characterized in that it is Ω · cm.

That is, the zirconia sintered body of the present invention contains TiO ₂ as a conductivity-imparting agent, which does not adversely affect semiconductors and electronic parts.
Dissolves in ZrO2 to form a grain bond, and the volume resistivity of the sintered body can escape static electricity of 10 ⁶ to 10 ¹⁰ Ω · cm at an appropriate speed without significantly lowering the strength of zirconia. The inventors have found that it can have semiconductivity.

Since the static electricity can be released at an appropriate speed, even if the object in contact with the zirconia sintered body is susceptible to electrical influence, the static electricity can be removed without breaking.

When the open porosity of the zirconia sintered body is set to 0.3% or less, the zirconia sintered body hardly absorbs moisture, so that the volume resistivity value affected by the humidity change is It can be a stable range.

The elastic modulus of the zirconia sintered body is
By setting it to 190 GPa or less, for example, when the sintered body is used as a processing jig for semiconductors or magnetic heads, etc., when the workpiece is supported by the jig, the jig side is slightly deformed As a result, the jig can reliably support the workpiece, and the processing accuracy can be improved.

ZrO ₂ containing at least a stabilizer
Of 80 to 95% by weight, as a conductivity-imparting agent, TiO ₂
5 to 20% by weight of a raw material, a step of firing the shaped body after the shaping in an oxidizing atmosphere, and a step of performing reduction firing of the fired body after the firing in an Ar gas atmosphere. The method for producing a zirconia sintered body is characterized in that the sintered body after reduction firing has a volume resistivity value of 10 ⁶ to 10 ¹⁰ Ω · cm.

According to the present invention, TiO ₂ which does not adversely affect semiconductors and electronic parts is used as an additive, and the resistance value can be adjusted within an appropriate range by performing reduction baking after oxidation baking, and Since the zirconia sintered body also changes from ivory color to black, it can be easily distinguished from the product in the manufacturing process as a jig, for example.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be further described below.

ZrO _{2 as a} main component is partially stabilized with a stabilizer such as Y ₂ O ₃ and a trace amount of Al ₂ O ₃ is used as a sintering aid.

Specifically, when Y ₂ O ₃ is used as a stabilizer, it is added in the range of 3 to 5% by weight with respect to ZrO ₂ , but if the stabilizer is added in this range, the crystalline state is obtained. As the tetragonal zirconia content relative to the total zirconia content can be 90% or more, the strength reduction due to the inclusion of the conductivity-imparting agent is suppressed, and the bending strength is 580MP.
It is possible to realize high hardness of a or more and Vickers hardness of 8.5 GPa or more. ZrO ₂ containing stabilizer at this time
As 80% to 95% by weight. If it is less than 80% by weight, the volume resistivity value is in the order of 10 ⁵ Ω · cm, which is 95
If it is more than wt%, the volume resistivity value will be in the order of 10 ¹¹ Ω · cm, which is not desirable in terms of static electricity removal measures.

That is, the crystalline state of zirconia is cubic,
There are three states, tetragonal and monoclinic. Especially, tetragonal zirconia undergoes stress induced transformation to external stress and undergoes phase transformation to monoclinic zirconia, and the volume expansion that occurs at this time causes zirconia to surround the zirconia. Since minute microcracks can be formed to prevent the progress of external stress, the strength of the zirconia sintered body can be increased.

Therefore, the zirconia sintered body is used to separate the paper from the rollers in the thin-walled transfer arm used in the semiconductor manufacturing apparatus or the wafer holding tweezers, or in the image forming apparatus such as the printer. By forming claws, tape guides used to convey and guide tape-shaped bodies such as magnetic tapes, drive carriers for taping and packaging equipment for electronic parts, etc., they will not be worn or damaged in a short period of time. It can be preferably used for a long period of time.

Next, the content of TiO ₂ as the conductivity-imparting agent is set to 5 to 20% by weight, preferably 10 to 15% by weight, so that the volume resistivity value range required for static electricity removal is obtained. A zirconia sintered body can be provided.

When the content of the conductivity-imparting agent is less than 5% by weight, the effect of lowering the resistance value is small, and when it is more than 20% by weight, the resistance value is "less than 10 ⁶ Ω · cm".
Since static electricity can easily escape at once, there is a possibility that an ultrahigh voltage discharge will occur due to atmospheric friction, and
Since the mechanical properties (bending strength, hardness, etc.) of the sintered body are significantly reduced, the original mechanical properties of zirconia cannot be exhibited. In the raw material powder and the manufacturing process, A
Although l ₂ O ₃ , MnO, SiO ₂ , Na, Fe and the like may be mixed as impurities, these may be contained in the range of 6.0 wt% or less.

On the other hand, in order to produce such a semiconductive zirconia sintered body, ZrO ₂ powder having an average particle diameter of 0.3 to 0.8 μm, Y ₂ O ₃ powder as a stabilizer, and T having an average particle size of 0.2 to 0.8 μm as a conductivity-imparting agent
A mixture is prepared by using iO ₂ , and these are mixed in a wet manner, and dried and granulated with a spray dryer or the like to produce granules.

Then, a raw material powder by a dry method or a granule by a wet method is filled in a mold and molded into a predetermined shape by a known molding means such as a mechanical press molding method or a rubber press molding method, or a wet slurry is extrusion molded. 2 to 4 in the maximum temperature range in an oxidizing atmosphere after being molded into a predetermined shape by a known molding means such as a molding method, an injection molding method, or a tape molding method.
Bake for about an hour. At this time, if the firing temperature is lower than 1380 ° C., the sintering cannot be completed completely, and if the firing temperature is higher than 1480 ° C., the sintering will be over, so that neither strength nor hardness of the zirconia sintered body can be increased. Therefore, it is important to fire at a temperature of 1380 to 1480 ° C.

Next, in reduction firing in an Ar gas atmosphere,
An oxidative calcination body is placed on a calcination base plate of carbon by a known calcination means, and irrespective of normal pressure or high pressure calcination under HIP
It is important to fire at a temperature of 200 to 1300 ° C. The use of HIP is desirable because the sintered body can be made dense and the open porosity described later can be made smaller.

When manufactured under such conditions, the amount of tetragonal zirconia to the total amount of zirconia is 90% or more, the bending strength is 580 MPa or more, the Vickers (Hv) hardness is 8.5 GPa or more, and at room temperature. The influence of humidity change in the humidity range of 10 to 65% is extremely small, and a zirconia sintered body having a volume specific resistance value of "10 ⁶ to 10 ¹⁰ Ω · cm" can be obtained. The reason why it is less likely to be affected by the humidity is considered to be that the open porosity of the zirconia sintered body is 0.3% or less. The open porosity is SEM: scanning type electric microscope, "applied voltage: 15 KV, magnification: 1000x".
Is a calculation of the area ratio of open pores in the visual field.

Further, the elastic modulus of the zirconia sintered body of the present invention is 190 Gp even when compared with the low elasticity (usually, elastic modulus of about 200 GP) which is also a mechanical feature of the zirconia sintered body.
Since it is a or less, and has elastic material characteristics similar to those of stainless steel, it can be used for ceramic products having a spring mechanism.

Next, a method of manufacturing the sintered body will be described. For ZrO ₂ powder having an average particle size of 0.4 μm, Y ₂
Granules were produced by adding 5% by weight of O ₃ powder and 15% by weight of TiO ₂ powder as a conductivity-imparting agent, further adding a binder and a solvent and kneading and drying. Then, the granules were filled in a mold and formed into a predetermined shape by a mechanical press forming method with a press pressure of 1.0 ton / cm 2, and after that, the mixture was fired in an air atmosphere at 1430 ° C. for about 2 hours. A zirconia sintered body was obtained by performing reduction firing in an Ar gas atmosphere at 1250 ° C. for about 2 hours.

Then, the X-ray diffraction intensity of monoclinic zirconia and the X-ray diffraction intensities of tetragonal zirconia and cubic zirconia were measured for each zirconia sintered body by X-ray diffraction. When the amount of zirconia was calculated, 99% was tetragonal zirconia.

Further, the above zirconia sintered body was subjected to bending strength measurement piece "3 mm x 4 mm x 40 mm" and elastic modulus measurement piece "1".
mm × 4 mm × 40 mm ”, the surface was ground to a center line average roughness of 0.2 a or less to prepare a sample, and the sample was tested for bending strength by a three-point bending test based on JIS R1601, When the static elastic modulus was measured according to JIS R1602, it had a bending strength of 598 MPa and an elastic modulus of 166 GPa. The elastic modulus was calculated by the following formula. W: Maximum load [dyn] L: Support roll center distance [c
m] h: width of test piece [cm] δ: amount of deflection [cm] b:
The thickness of the test piece [cm] E: elastic modulus ^{[dyn / cm 2] E =} W × (L) 3/4 × δ × W × (b) 3 Normally the Y ₂ O ₃ is 3 mol% content The elastic modulus of the zirconia sintered body is about 200 to 210 GPa.

Another sample was prepared using the same raw material as above, and the Vickers hardness (Hv) was measured to be 9.0 G.
It had Pa, and when the volume resistivity value was measured with another sample, it was 2.0 × 10 ⁷ Ω · cm.

Therefore, in order to see how static electricity is removed,
Prepare a zirconia sintered body with a square plate of "50.8 mm x 50.8 mm x 5 mm", apply a voltage of 1000 V to one end, and measure the fall time until the voltage value at the other end reaches 100 V. As a result, it took 0.1 to 20 seconds, and it was good that static electricity could be released at an appropriate speed without causing discharge due to atmospheric friction.

In the zirconia sintered body in the above embodiment
TiO which is a conductivity-imparting agent _TwoThe content of
Mechanical properties when bent (bending strength, Vickers hardness, elasticity
Sex rate) and electrical characteristics (volume resistance value)
It was For the mechanical and electrical characteristics,
It measured by the method similar to embodiment.

The respective results are shown in Table 1.

[0033]

[Table 1]

As a result, the content of TiO ₂ was 5% by weight.
The sample of less than 10 had excellent mechanical properties of zirconia, but had a volume resistivity of 10 ¹¹ Ω · c.
Since the insulating property was high as m or more, the effect of removing static electricity was not obtained.

Further, in the sample of 25% by weight in which the content of TiO ₂ is more than 20% by weight, the mechanical properties are deteriorated, but the bending strength is 568 MPa or more and the Vickers hardness (Hv) is 8.2 GPa or more. Was. However, since the content of TiO ₂ is too large, the volume resistivity value is lowered to 10 ⁵ Ω · cm, and as a result, static electricity escapes at once.

On the other hand, the content of TiO ₂ is 5 to 20.
Bending strength is 585M for all samples in the range of weight%
It had excellent mechanical properties of Pa or more and Vickers hardness (Hv) of 8.7 GPa or more.

Moreover, the surface and specific volume resistance values are set to "10.
⁶ to 10 ¹⁰ Ω · cm ”, static electricity can be released at an appropriate speed, and it also has an excellent static electricity removing effect.

As a result, when the content of TiO ₂ which is a conductivity-imparting agent is in the range of 5 to 20% by weight, the semi-conductivity having an excellent static electricity removing effect without significantly deteriorating the mechanical properties of zirconia. It can be seen that a sintered zirconia sintered body can be obtained.

Further, in the present invention, it is diverted that the zirconia sintered body is given a color close to black by performing reduction firing, and partial reoxidation due to high temperature heat is carried out by CO ₂ and YAG laser marking. Due to the phenomenon, it is possible to develop white, and it is possible to print barcodes in addition to numerical values and letters.

[0040]

As described above, the semiconductive zirco of the present invention is used.
The near-sintered body is ZrO containing a stabilizer. ₂ 80 to 95 layers
%, And TiO as a conductivity-imparting agent_Two5 to 20 weight
%, And the volume resistivity value is “10⁶-10
¹⁰ Ω · cm ”, so as a heavy metal impurity
A machine with zirconia that does not contain additive metals that adversely affect
Static electricity can be moderated without significantly reducing the mechanical properties.
You can escape at speed.

Claims (4)

[Claims] 1. ZrO containing a stabilizer₂ 80 to 95 weight
%, And TiO as a conductivity-imparting agent ₂5 to 20% by weight
Containing at least and having a volume resistivity value of 10⁶-10
¹⁰Zirconia sintering characterized by Ω · cm
body. 2. The zirconia sintered body has an open porosity of 0.
The zirconia sintered body according to claim 1, which is 3% or less. 3. The elastic modulus of the zirconia sintered body is 190.
It is below Gpa, The zirconia sintered compact of Claim 1 characterized by the above-mentioned. 4. ZrO ₂ containing at least a stabilizer 80
~ 95 wt% and 5 to 5% TiO ₂ as a conductivity-imparting agent.
20% by weight at least, a step of molding using a raw material, a step of firing the shaped body after the shaping in an oxidizing atmosphere, and a step of performing reduction firing of the fired body after the firing in an Ar gas atmosphere. A method for producing a zirconia sintered body, wherein the volume resistivity of the sintered body after the reduction firing is 10 ⁶ to 10 ¹⁰ Ω · cm.