JPH02111660A - Production of ceramic thin film-like shaped article - Google Patents

Abstract

PURPOSE:To obtain ceramics having thin film-like and threedimensionally complex shape by performing deep drawing processing under specific condition to thin plate-like sintered material obtained by burning green sheet of zirconia- based ceramic. CONSTITUTION:Green sheet of zirconia-based ceramics burned to form thin plate-like sintered material having <=2mm thickness and the sintered material is subjected to deep drawing processing under the condition satisfying the following equations to afford thin film-like shaped article: logV<=(0.01/d).(T-1350); 1400<=T<=1500. In said equations, V is press speed (mm/min) in deep drawing processing; T is maximum heating temperature ( deg.C) in deep drawing processing and d is thickness (mm) of thin plate-like sintered material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a ceramic thin film molded body that is widely used for sensor elements, electronic parts, mechanical parts, etc.

[Conventional technology] Ceramics have excellent electrical and optical properties.

Because it exhibits heat conduction properties, it is widely applied to electronic parts, mechanical parts, etc. For example, ceramics molded into thin plates are used for IC insulating substrates, capacitors, etc., and ceramics molded into bag tube shapes are used for sensor elements of gas detection sensors, etc.

The former thin plate-shaped molded product can be obtained by press molding or a doctor blade method, and the doctor blade method is particularly suitable when obtaining a thin product. This method is tape casting, which is an application of slurry casting, in which a slurry (slip) obtained by mixing ceramic powder with binder, plasticizer, solvent, etc. is cast onto the tape being fed. This is a method in which the thickness is adjusted with a doctor blade and then fired. According to this method, a thin plate molded body having a thickness of 10 μm to 1 mm can be easily produced. On the other hand, three-dimensional shaped products such as bag tubular molded products are generally obtained by casting, but if a mold cannot be made, they may be made by injection molding. However, in any case, when forming such a three-dimensional shape, the thickness at any location is set to 211II11 or more so that the shape does not collapse during demolding or firing.

[Problems to be Solved by the Invention] However, even in the above-mentioned three-dimensionally shaped ceramic, it may be desired to make each part a thin film of 1 mm or less in thickness. For example, the sensor element of an oxygen gas detector uses bag-tube-shaped ceramics as described above, but in order to improve the performance of the sensor element, it is necessary to reduce the thickness of the ceramic to reduce its resistance. In other words, if a bag tube-like and thin film-like product can be obtained, ■ response speed will be faster, ■ noise will be reduced, ■ low-temperature operability will be improved, and ■ responsiveness and sensitivity will be improved in the trace oxygen range. , etc. There is one advantage. However, since a molding technique for obtaining a bag-tube-like thin film with a thickness of 1 mm or less has not been established, a thin-film bag-tube-like product has not been obtained.

The present invention has been developed in light of the above circumstances, and an object of the present invention is to provide a manufacturing method that allows ceramics to be formed into a thin film-like three-dimensional complex shape.

[Means for solving problems]

In order to achieve the above object, the method for manufacturing a ceramic thin film shaped body of the present invention involves firing a green sheet of zirconia ceramics into a thin plate shaped sintered body of 2 mm or less, and then applying the steps to the above sintered body. The structure is such that a thin film-like molded product is formed by deep drawing under conditions that satisfy the following formula.

1400≦T≦1500 In the above equation, (1) is the press speed during deep drawing (k/min), T is the maximum heating temperature during deep drawing (°C), and d is the thickness of the thin plate-shaped sintered body (
mm) [Function] That is, the present invention uses a known method such as the doctor blade method to obtain a thin plate-shaped sintered body of two bars or less, and then deep-draws it under special conditions to form a tertiary product. This is an original thin film molded product.

When the above-mentioned special conditions are followed, even a thin plate-like sintered body exhibits a plastic phenomenon and undergoes desired deformation during deep drawing.

Next, the present invention will be explained in detail based on examples.

〔Example〕

First, a slip was prepared by blending zirconia powder (manufactured by Tosoh Corporation, average particle size: 0.05 μm), a solvent, a binder, a plasticizer, and a dispersant in the proportions shown in Table 1 below. The preparation procedure is to first mix the binder and solvent and
Melts at temperatures of ~100°C. Next, zirconia powder, a dispersant, and a solvent were added, and the mixture was mixed and stirred for 5 hours using an automatic mortar.

At this stage, the binder is completely dissolved and the agglomerated powder grains are ground. This is because if particles of the agglomerated powder remain, the particles will be caught by a doctor blade during the green sheet production step described later, causing damage to the sheet. This way you get a smooth slip.

(Left below) The slip obtained in this way was collected in the slip holder of a known doctor blade WZ (DP 100),
A green sheet was produced by casting by adjusting the blade height and feed speed.

Although the green sheet may be force-dried, it was air-dried in this example. Then, 8 pieces of dried green sheet
It was cut into a rectangle of 0 mm x 90 mm, covered with alumina fiber, and fired. A known electric furnace (manufactured by Motoyama Co., Ltd.) was used for firing. Note that prior to firing, it was necessary to degrease the green sheet, and first, differential thermal analysis was performed to measure the combustion temperature of organic matter. As a result, about 6
It was found that most of the oil burned at 50'C, so it was decided to perform degreasing by setting the degreasing temperature to 75 o'C and the degreasing time to 30 minutes.

An alumina fiber sheath is used as the firing container, but if the green sheet is placed inside the sheath, temperature unevenness will occur on the front and back surfaces of the green sheet, and the edges of the resulting sintered body will be warped. Since it was found that the pods were prone to cracks and cracks, the pod was filled with cotton-like alumina fibers and a green sheet was placed inside the pod.

Firing temperature 1 was set to rise at a rate of 100°C/min, and cooled at a rate of 100°C/min. The thin plate-like sintered body obtained by firing has ta compared to the size of the green sheet.
, both sides shrunk by about 30%. Almost no change in thickness was observed.

The phase structure of the thin plate-like sintered body was examined using an X-ray diffraction apparatus. Zirconia can have either a monoclinic system or a tetragonal cubic system structure, but 3 mol Y20. Most of the doped zirconia (TZ-3Y) is tetragonal,
A slight monoclinic system may occur. On the other hand, 8
The zirconia doped with molar Y2O3 (TZ-8Y) was all cubic system. As a result of examining the bending strength of 3 mol YzO3-added zirconia, it was found to be 30 kg r 7mm'' at a maximum heating temperature of 1400'C.The strength decreased regardless of whether the maximum heating temperature was higher or lower than 1400°C. It was seen.

A 3 mol Y2O3-added zirconia sintered body sintered at a maximum heating temperature of 1400°C was cut into a disc shape with an outer diameter of 42 mm (thickness 2 mm), a press diameter of 20 mm, and a die inner diameter of 25 m.
Deep drawing was performed using a drawing die of size m. The temperature is 12
20'C/min up to 00°C, 1200-1450'
At C, the temperature should be raised at 15'C/min to 1450°C.
After reaching this temperature, this temperature was maintained for 60 minutes, and then drawing was performed with a stroke of about 15 mm using a double-acting press. Then, it was naturally cooled to obtain a bag tubular molded product.

In addition, in order to investigate the limit value at which the sintered body can be plastically deformed in the deep drawing process described above, the relationship between press speed and maximum press load is summarized in Figure 1.

By the way, the maximum press load P max is practically expressed by the following formula.

Pmax=I Dz to 6t C+--(1)
D2: Molded object outer diameter, to: Sample thickness σL:
Tensile strength of sample C1: Coefficient related to drawing ratio Therefore, the reason why the maximum press load tends to increase as the pressing speed increases in Fig. 2 is because the tensile strength of the sample increases with plastic deformation. Conceivable.

The molded product obtained in this way has a black color on both the outer and inner surfaces due to the adhesion of carbon from graphite, which is the material of the drawing mold, due to the high temperature during pressing, but it can return to its original white color by reheating. Can be done.

Next, the thickness of the 3 mol Y2O3-added zirconia sintered body was reduced from 2 mm to 1.0 mm and 0.5 mm, and deep drawing was performed. The thinner the sample, the more likely wrinkles will appear in the resulting molded product, so to prevent this, it is better to make the gap between the drawing die and the sample as small as possible. However, if the diameter is too small, the sample will easily break at the shoulder, so the press diameter should be 20 mm.
The inner diameter of the die was set to 23M, and the gap was set to 1°5 mm. Also, the press speed is 0
．． Three different speeds were used: 2.0°, 5.1.0 mm/min. The results are shown in FIG. According to the above equation (1), the maximum press load Pwax is proportional to the thickness to of the sample, but such a relationship cannot be obtained from FIG. 2. This is considered to be because the coefficient 01 related to the reduction rate changed due to the difference in sample thickness.

The molded product thus obtained was in good condition, with no cracks occurring in the 2 mm thick molded product. However, the outer edge of the one with a thickness of 1.0 mm was slightly wavy (ear phenomenon), and the one with a thickness of 0.5 mm had wrinkles.

Furthermore, 3 mol Y2O3 added zirconia sintered body (thickness 2
In order to investigate the influence of the processing temperature during deep drawing on the plastic deformation of the sintered body, the predetermined temperature was set to 1.
Deep drawing was performed at four different temperatures: 350°C, 1400°C, 1450°C, and 1500°C. The temperature increase to reach the above temperature is 15°
C/min, and the time for maintaining the above temperature was 60 minutes.

In addition, the press speed is 0.2, 0.5, 1.0
The number of mm was 3/7. However, in the case of 1350°C, all the samples were broken during processing. Further, at 1400°C, molding was good although slight racking occurred at the shoulder. 1450°C and 1
At 500°C, a smooth molded product was obtained without any cracks.

From these experimental data, it is possible to express suitable deep drawing conditions using an objective mathematical formula. That is, first, based on the following equation, the relationship between press load and press speed is changed to the relationship between press pressure and press speed.

Press pressure = Press load ÷ Punch area For example, when the press temperature is 1450° C., the press pressure P is expressed by a linear equation as a function of the press speed V, as shown in FIG. Similarly, linear equations relating to press pressure P and press speed can be obtained for 1400°C and 1500°C.

By the way, regardless of the heating temperature, if the press pressure exceeds 200 kg/cffl, damage to the press jig or destruction of the sample will occur, so it is recommended to set the upper limit of the press pressure to 2 Q Okg/CTII. can. Therefore, from the above three linear equations, the press pressure is 200
The press speed at which kg/crA is obtained is calculated, and this is set as the maximum press speed (V). The relationship between the value of V thus determined and the heating temperature during pressing is summarized as shown in FIG. 4.

The following equation can be obtained from the equations of the three straight lines shown in this figure.

1400≦T≦1500 ■: Maximum press speed (mm/min) Sample thickness (mm) T: Heating temperature (°C) This indicates the maximum press speed, so perform proper deep drawing. The press speed that can be achieved can be expressed by the following inequality.

l 400≦T≦1500 ■;Press speed (min/min) t: Sample thickness (mm) T: Heating temperature (°C) Therefore, under the conditions that satisfy the above formula, the thin plate-shaped sintered body is By deep drawing, a three-dimensional shaped thin film shaped body can be obtained.

〔Effect of the invention〕

As described above, according to the method for producing a thin film shaped body of the present invention, deep drawing can be performed on a thin plate shaped sintered body.
It is possible to obtain a molded article with J′;< of m or less.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between press speed and maximum press load at a press temperature of 1450°C, Figure 2 is a diagram showing the relationship between sample thickness and maximum press load, and Figure 3 is a diagram showing the relationship between sample thickness and maximum press load at a press temperature of 1.450°C. A diagram showing the relationship between press speed and press pressure in C, and the fourth circle is a diagram showing the relationship between the heating temperature and the common logarithm of the maximum press speed.

Claims (1)

[Claims] (1) After firing a green sheet of zirconia ceramics into a thin plate-like sintered body of 2 mm or less, the above-mentioned sintered body is deep-drawn under conditions that satisfy the following formula to form a thin film-like molded body. A method for producing a ceramic thin film shaped body, characterized by: logV≦(0.01/d)・(T-1350)140
0≦T≦1500 In the above formula, V is the press speed during deep drawing (mm/min) T is the maximum heating temperature during deep drawing (℃) d is the thickness of the thin plate-shaped sintered body (mm)