JPH07291719A - Alumina sintered compact - Google Patents

Abstract

PURPOSE:To reduce the temp. coefft. of volume resistivity by incorporating Al2O3 and an additive compsn. consisting of MnO2, one or more kinds of oxides of group Va elements of the Periodic Table and one or more kinds of oxides of iron family metals in a specified ratio. CONSTITUTION:A blend is prepd. by blending Al2O3 with MnO2, one or more kinds of oxides of group Va elements of the Periodic Table such as Nb2O5 and Ta2O5 and one or more kinds of oxides of iron family metals such as Fe2O3 and NiO in a specific ratio. The blend is wet-mixed and spray-dried. The resultant powdery starting material is press-compacted, is burnt at about 1,200-1,500 deg.C for about 1-3hr in an oxidizing atmosphere to obtain the objective Al2O3 sintered compact consisting of 70-93wt.% Al2O3 and 7-30wt.% additive compsn. consisting of 15-90wt.% MnO2, 3-40wt.% oxides of group Va elements of the Periodic Table and 5-80wt.% oxides of iron family metals. This sintered compact has 1X10<7>-1X10<12>OMEGAcm volume resistivity in the temp. range of 25-75 deg.C and <=1.8%/ deg.C temp. coefft. of volume resistivity in the temp. range of 25-75 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alumina-based sintered body containing alumina as a main component. For example, antistatic parts (for example, parts required to prevent static electricity in semiconductor manufacturing equipment etc. (transport arms, handling jigs, etc.). Tools, wafer gripping tweezers, etc.)), resistance substrates, conductive materials, contacts, heaters, vacuum tube parts, etc.

[0002]

2. Description of the Related Art Conventionally, for example, antistatic parts (for example,
Parts such as semiconductor arms that require static electricity prevention (transport arms, etc.), resistance substrates, conductive materials, contacts, heaters, vacuum tube envelopes, etc., have a volume resistivity in the middle between the insulator and the conductor. A ceramic having (for example, 1 × 10 ⁷ to 1 × 10 ¹³ Ωcm) is used.

As such ceramics, an alumina sintered body is known. In such an alumina-based sintered body, for example, a powder of alkali metal, titanium, or an oxide thereof is added to alumina powder, and the mixture is mixed by a dry method or a wet method, and a molding aid is added if necessary. It was manufactured by sintering in a reducing atmosphere in order to obtain a desired resistance value.

[0004]

However, in such an alumina-based sintered body, when it is used from room temperature to a high temperature range, its volume resistivity decreases as the temperature rises. When the sintered body is used as the resistance substrate, there is a problem that the resistance value largely changes depending on the temperature. Further, there is a problem that the volume resistivity increases as the temperature decreases, and the desired antistatic effect cannot be obtained.

That is, in the conventional alumina sintered body, 25
Temperature coefficient of volume resistivity in the range of ~ 75 ℃ is 2% / ℃
There is a problem in that the rate of change in volume resistivity with respect to temperature is large. The temperature coefficient TCR (% / ° C) of the volume resistivity is TCR (% / ° C) = [(R ₂₅ -R
₇₅ ) / (R ₂₅ × 50)] × 100. Here, R ₂₅ is the volume resistivity at 25 ° C., and R ₇₅
Is the volume resistivity at 75 ° C.

[0006]

Means for Solving the Problems The inventors of the present invention have made extensive studies on the above problems, and as a result, have alumina as a main component, and manganese dioxide and 5a of the periodic table.
In the alumina sintered body containing at least one selected from the group-group element oxides and a predetermined amount of at least one selected from the iron-group metal oxides, within the temperature range of 25 to 75 ° C.
It has a volume resistivity of × 10 ⁷ to 1 × 10 ¹³ Ωcm and 2
The inventors have found that the temperature coefficient of volume resistivity within a temperature range of 5 to 75 ° C. is 1.8% / ° C. or less, and completed the present invention.

That is, the alumina-based sintered body of the present invention is an alumina-based sintered body composed of 70 to 93% by weight of alumina and 7 to 30% by weight of the additive component, and the additive component is 15% by weight of manganese dioxide. ˜90% by weight, at least one type 3 to 40% by weight of Group 5a element oxide of the periodic table, and at least one type 5 to 80% by weight of iron group metal oxides. Also, within the temperature range of 25 to 75 ° C, 1
An alumina sintered body having a volume resistivity of x10 ⁷ to 1 x 10 ¹³ Ωcm and a temperature coefficient of volume resistivity of 1.8% / ° C or less within a temperature range of 25 to 75 ° C. .

In the above-mentioned sintered body of the present invention, the alumina content is set to 70 to 93% by weight because the amount of alumina is less than 70% by weight (additional component is more than 30% by weight).
When the volume resistivity is less than 1 × 10 ⁷ Ωcm and approaches the conductor, the volume resistivity is 1 × when the content is more than 93% by weight (the additive component is less than 7% by weight). This is because it becomes larger than 10 ¹³ Ωcm and approaches the insulator. Alumina is 75 to 8 in terms of having a volume resistivity of 1 × 10 ⁷ to 1 × 10 ¹³ Ωcm.
The content is preferably 5% by weight, and is preferably 80 to 93% by weight from the viewpoint of strength and sinterability of porcelain.

In addition, the inclusion of manganese dioxide in the additive component improves the sinterability and enables firing at a relatively low temperature,
Also, it is easy to obtain a desired volume resistivity. Here, when the additive components are expressed by weight ratio, manganese dioxide is 1
The content of 5 to 90% by weight is included because if the content of manganese oxide is less than 15% by weight, the volume resistivity becomes larger than 1 × 10 ¹³ Ωcm and approaches an insulator. If there are many, the volume resistivity is 1 × 10
^This is because it becomes smaller than ⁷ Ωcm and approaches the conductor.
From the viewpoint of having a volume resistivity of 1 × 10 ⁷ to 1 × 10 ¹³ Ωcm, manganese dioxide is preferably contained in an amount of 18 to 85% by weight, particularly preferably 30 to 80% by weight, and it is desirable to add porcelain to the ceramic. 30 from the point of connectivity
It is desirable to contain 90% by weight.

Further, the reason why at least one of the oxides of Group 5a elements of the periodic table is contained in the additive component is that a desired volume resistivity can be easily obtained and the temperature coefficient of volume resistivity tends to be small. Is. When the additive component is expressed by weight ratio, at least one of Group 5a element oxides of the periodic table is made to be 3 to 40% by weight because the volume resistivity temperature is lower than 3% by weight. Coefficient is 1.8% /
This is because the temperature becomes ℃ or more and the volume resistivity with respect to temperature increases. On the other hand, when it is more than 40% by weight, the volume resistivity becomes smaller than 1 × 10 ⁷ Ωcm and approaches the conductor. The oxide of Group 5a element of the periodic table has a small volume resistivity and preferably contains 3.5 to 30% by weight, and particularly preferably contains 3.5 to 25% by weight from the viewpoint of obtaining a desired volume resistivity. It is desirable to let The elements of Group 5a of the periodic table include vanadium, niobium, and tantalum, and niobium is particularly preferable in the present invention.

Furthermore, the reason why at least one of the iron group metal oxides is contained in the additive component is that a desired volume resistivity can be easily obtained. When the additive component is expressed by weight ratio, at least one of the iron group metal oxides is made 5 to 80% by weight because the volume resistivity is 1 × 10 ¹³ Ωcm when it is less than 5% by weight. This is because the volume resistivity becomes smaller than that of the conductor and the volume resistivity becomes smaller than 1 × 10 ⁷ Ωcm and becomes closer to the conductor when it is more than 80% by weight. The iron group metal oxide is 10 to 80% by weight from the viewpoint of obtaining a desired volume resistivity.
It is preferable to contain it, and it is particularly preferable to contain 10 to 60% by weight. The iron group includes iron, cobalt,
There is nickel, and iron is particularly preferable in the present invention.

And, in the alumina-based sintered body of the present invention,
80-85% by weight of alumina and 15-20 added components
% Of manganese dioxide in the additive component, 26 to 65 wt% of iron oxide, 27 to 65 wt% of iron oxide,
Optimally, the niobium oxide is 5 to 15% by weight.

Further, in the present invention, it is desirable to have a volume resistivity of 1 × 10 ⁹ to 1 × 10 ¹² Ωcm in the temperature range of 25 to 75 ° C., and in the temperature range of 25 to 75 ° C. The temperature coefficient of volume resistivity is preferably 1.6% / ° C. or less.

Such an alumina-based sintered body is, for example,
Alumina powder, manganese oxide powder, oxide powder of Group 5a element of the periodic table, oxide powder of iron group metal, or hydroxide powder of the above materials, which can be changed to these materials during firing, It is obtained by using carbonates, mixing them, shaping them into a predetermined shape by a desired shaping means, and firing at 1200 to 1500 ° C. for 1 to 3 hours in an oxidizing atmosphere. The raw material powders may be mixed by a dry method, but when they are mixed by a wet method, they are granulated by spray drying or the like and molded.

In the case of pulverizing and mixing with a ball mill or the like, calcium oxide, chromium oxide, cobalt oxide, magnesium oxide, silica, manganese oxide, iron oxide may be mixed from the balls, but in the range satisfying the above composition. If it is inside, there is no problem.

[0016]

The alumina sintered body of the present invention mainly controls the alumina content and the content of the additive component, and the content of the Group 5a element oxide of the periodic table, the amount of manganese oxide, the content of the iron group in the additive component are controlled. 25 to 7 by controlling the amount of metal oxide
It has a volume resistivity of about 0.01 to 10000 GΩcm in the temperature range of 5 ° C, and can have a temperature coefficient of the volume resistivity of 1.8% / ° C or less in the temperature range of 25 to 75 ° C. Becomes

The present invention will be described below with reference to the following examples.

[0018]

【Example】

Example 1 First, an alumina powder, a manganese oxide powder, a Group 5a element oxide powder of the periodic table, and an iron group metal oxide powder were prepared, and the composition of the sintered body was as shown in Tables 1 and 2. After weighing so as to have a ratio, they were wet mixed in a rotary mill. The mixed slurry was dried by spray drying to obtain a raw material for sintering. This was press-molded and fired in the atmosphere at the temperatures shown in Table 1 and Table 2 for 2 hours to obtain a disk-shaped sintered body having a diameter of 60 mm and a thickness of 3 mm. Then, both ends of this were polished so that the thickness of the sample was 2 mm.

[0019]

[Table 1]

[0020]

[Table 2]

Then, this sample was tested according to JIS C 214
Based on the insulation resistance measurement method specified in 1, the sample is housed in a vacuum of about 10 ^-6 torr, the terminals of the super insulation resistance meter are connected to the electrodes on both ends of the sample, and the temperature inside the vacuum device is 25 ° C. 7
After reaching the desired temperature of 5 ° C for 10 minutes,
The resistance value when 1000 V was applied to the sample for 5 minutes was read. The volume resistivity was calculated from this resistance value, and the temperature coefficient of the volume resistivity was determined. Volume resistivity is JIS C
2141, R = r × S / t (R:
The volume resistivity, r: resistance value, S: electrode area, t: sample thickness) were used. Also, the temperature coefficient TC of the volume resistivity
R (% / ° C) is TCR (% / ° C) = [(R ₂₅ -R ₇₅ ).
/ (R ₂₅ × 50)] × 100. Here, R ₂₅ is the volume resistivity at 25 ° C., and R ₇₅ is the volume resistivity at 75 ° C. The results are shown in Tables 1 and 2.

From Tables 1 and 2, the alumina-based sintered body of the present invention has a temperature range of 25 to 75 ° C. of 1 × 10 ⁷ to
It has a volume resistivity of 1 × 10 ¹³ Ωcm and 2
It can be seen that the temperature coefficient of volume resistivity within the temperature range of 5 to 75 ° C is 1.8% / ° C or less. On the other hand, samples No. 1, 7, 16, 20, 22, 24, 26 outside the scope of the present invention
Is 1 × 10 ⁷ to 1 × 10 within the temperature range of 25 to 75 ° C.
It does not have ¹³ Ωcm, and the samples No. 1 and 18 are
It can be seen that the temperature coefficient of volume resistivity is 1.8% / ° C or higher in the temperature range of 25 to 75 ° C.

Further, in the past, the cost was high because firing was carried out in a reducing atmosphere in order to obtain a desired resistance value, but according to the alumina-based sintered body of the present invention, firing was performed in the atmosphere. It is possible to inexpensively obtain an alumina-based sintered body having a desired resistance value.

[0024]

As described above in detail, the alumina-based sintered body of the present invention has a temperature range of 25 to 75 ° C. and a concentration of 1 × 10 ⁷ to
It has a volume resistivity of about 1 × 10 ¹³ Ωcm, and has a temperature coefficient of volume resistivity of 1.8% / ° C. or less in the temperature range of 25 to 75 ° C., which is an intermediate volume between the insulator and the conductor. In addition to having a specific resistance, the width in which the volume specific resistance fluctuates depending on the temperature of the sintered body is significantly reduced, and a desired volume specific resistance can be easily obtained. For example, an antistatic component (for example, a semiconductor manufacturing device, etc.) To obtain the optimum alumina sintered body for parts that require static electricity prevention (transport arm, handling jig, tweezers for wafer gripping, etc.), resistor substrate, conductive material, contacts, heater, vacuum tube envelope, etc. be able to.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Toshihiko Uemura 1-1, Yamashita-cho, Kokubun-shi, Kagoshima Prefecture Kyocera stock company Kagoshima-Kokubun factory (72) Inventor Tsuneo Whip 6-735 Kitashinagawa, Shinagawa-ku, Tokyo No. Sony Corporation

Claims (2)

[Claims] 1. Alumina 70-93% by weight and additional component 7-
30% by weight of an alumina sintered body, wherein the additive component is 15 to 90% by weight of manganese dioxide and at least one of oxides of Group 5a element of the periodic table 3 to 40.
5% by weight and at least one of iron group metal oxides 5
An alumina-based sintered body characterized by comprising 80% by weight. 2. Within the temperature range of 25 to 75 ° C., 1 × 10 ⁷ to
It has a volume resistivity of 1 × 10 ¹³ Ωcm and 2
The alumina sintered body according to claim 1, wherein the temperature coefficient of volume resistivity in the temperature range of 5 to 75 ° C is 1.8% / ° C or less.