Patent Application
20190299485
The present invention relates to a method of performing deformation processing on a ceramic, and an apparatus therefor. More specifically, the present invention relates to a method of performing deformation processing on a ceramic at a low temperature in a short time, and an apparatus therefor.
A ceramic polycrystalline dense body has features such as high strength, a high shear modulus, corrosion resistance, and ion conductivity, and thus is used as various heat resistant materials, structural members, battery electrolytes, or the like. However, because a ceramic is brittle, it is difficult to perform deformation processing thereon. A technology is known for performing deformation processing on such a ceramic polycrystalline dense body at a high temperature (see, for example, Patent Literature 1).
Patent Literature 1 discloses that deformation processing is performed on a sintered ceramic body at a temperature of not less than 1300° C. The sintered ceramic body consists of zirconia matrix in which one or more spinel phases with the general formula MgAl2O4, MnAl2O4, or TiMn2O4 are uniformly dispersed, the zirconia phase and the spinel phases occupy not less than 80% of volume fraction of the sintered body, and the sintered body has an average grain size of not more than 2.0 μm.
However, the operation temperature for the deformation processing is as high as not less than 1300° C. and the strain rate is as slow as not less than 1×10−4s−1, which has hindered industrial practical use. Since the ceramic in Patent Literature 1 is a zirconia superplastic ceramic, a technology for easy deformation processing even on an arbitrary ceramic at a low temperature in a short time is desired.
Patent Literature 1: Japanese Patent Application Laid-open No. 2004-107156
It is an object of the present invention to provide a method of performing deformation processing on a ceramic at a low temperature in a short time, and an apparatus therefor.
A method of performing deformation processing on a ceramic according to the present invention includes a step of heating the ceramic within a temperature range of more than 700° C. and not more than 1400° C.; a step of applying a voltage to the heated ceramic; and a step of applying a stress to the heated ceramic to which the voltage has been applied, thereby solving the above-mentioned problem.
The step of heating may include heating the ceramic within a temperature range of not less than 800° C. and not more than 1200° C.
The step of heating may include heating the ceramic within a temperature range of not less than 800° C. and not more than 1000° C.
The step of applying a voltage may include applying a direct current electric field to the ceramic within a range of not less than 50 V/cm and not more than 1500 V/cm.
The step of applying a voltage may include applying a direct current electric field to the ceramic within a range of not less than 100 V/cm and not more than 200 V/cm.
The step of applying a voltage may include applying an alternating electric field to the ceramic within a range of not less than 5 V/cm and not more than 200 V/cm at a frequency within a range of not less than 1 Hz and not more than 60 Hz.
The step of applying a voltage may include applying an alternating electric field to the ceramic within a range of not less than 15 V/cm and not more than 60 V/cm at a frequency within a range of not less than 3 Hz and not more than 20 Hz.
The step of applying a voltage may include applying a current density of not less than 100 mA/mm2 and not more than 300 mA/mm2 to the ceramic.
The step of applying a voltage may include applying a current density of not less than 200 mA/mm2 and not more than 270 mA/mm2 to the ceramic.
The step of applying a stress may include applying a stress with a strain rate of not less than 1×10−3s−1 and not more than 1×10−1s−1 to the ceramic.
The ceramic may be polycrystalline selected from the group consisting of an oxide, a nitride, a carbide, and an oxynitride having a grain size of not less than 100 nm and not more than 1 μm.
The step of applying a stress may include applying a stress selected from the group consisting of a tensile stress, a compressive stress, and a bending stress to the ceramic.
The step of applying a voltage may include applying a voltage while controlling a current density flowing through the ceramic in such a way that the stress applied to the ceramic by the step of applying a stress is constant.
The step of applying a stress may be performed after applying the voltage to the ceramic for more than zero second and not more than 60 seconds in the step of applying a voltage.
The step of applying a stress may include applying a deformation stress to the ceramic within a range of not less than 5 MPa and not more than 150 MPa.
The step of applying a stress may include applying a deformation stress to the ceramic within a range of not less than 5 MPa and not more than 15 MPa.
An apparatus that performs deformation processing on a ceramic according to the present technology includes: a stress application means that applies a stress to the ceramic, the ceramic being placed on the stress application means; a heating means that heating the ceramic; and a power source that applies a voltage to the ceramic, thereby solving the above-mentioned problem.
The apparatus may further include a control unit that controls at least an operation of the power source, in which the control unit may control the operation of the power source in such a way that the stress applied by the stress application means is constant, or control the operation of the power source in such a way that the voltage is constant on a basis of an amount of strain that has occurred in the ceramic by the stress application means.
The stress application means may apply a stress selected from the group consisting of a tensile stress, a compressive stress, and a bending stress to the ceramic.
The power source may be a direct current power source or an alternating current power source.
The heating means may be selected from the group consisting of resistance heating, infrared heating, and combustion heating.
The deformation processing method according to the present invention includes: a heating step; a voltage application step; and a stress application step. Since the ceramic becomes an atomic diffusion self-accelerated state by the heating step and the voltage application step, applying a stress in this state makes it possible to perform deformation processing at a high strain rate (i.e., in a short time). Since the heating can cause the atomic diffusion self-accelerated state to occur as long as the heating temperature is higher than 700° C., it is possible to perform deformation processing at a low temperature of not more than 1000° C.
The deformation processing apparatus according to the present invention includes: a stress application means; a heating means; and a power source. With such a configuration, it is possible to perform deformation processing in a short time by causing a ceramic to be in an atomic diffusion self-accelerated state even at a low temperature of not more than 1000° C.
Hereinafter, embodiments of the present technology will be described with reference to the drawings. Note that similar components will be denoted by similar reference symbols, and description thereof will be omitted.
The present inventors have found that a ceramic becomes an atomic diffusion self-accelerated state by heating a ceramic and applying a voltage to the ceramic, and applied this to deformation processing to complete the present invention. In the present specification, the term “atomic diffusion self-accelerated state” represents the state in which atomic diffusion has been accelerated much more than normal atomic diffusion determined by the temperature in a ceramic. Note that in the present specification, it is determined when a voltage is applied to the ceramic, a predetermined current value is achieved, and the ceramic is plastically-deformed, that the ceramic has become an atomic diffusion self-accelerated state. For example, in the case where the ceramic is yttria-stabilized zirconia, the ceramic is surely plastically deformed when a voltage is applied thereto and 250 mA/mm2 is achieved. Therefore, it can be determined that it has become an atomic diffusion self-accelerated state when 250 mA/mm2 as a predetermined current value is achieved.
Examples of the material of the ceramic used in the present invention include, but not particularly limited to, polycrystals selected from the group consisting of an oxide, a nitride, a carbide, and an oxynitride. Examples of the oxide ceramic include, but not limited to, a zirconia ceramic typified by yttria-stabilized zirconia (Y2O3-stabilized tetragonal ZrO2), a composite ceramic typified by ZrO2—Al2O3—MgAl2O4, and an alumina ceramic (Al2O3). Examples of the nitride ceramic include, but not limited to, Si3N4, SiAlON, AlN, and TiN. Examples of the carbide ceramic include, but not limited to, SiC, TiC, B4C, and ZrC. The oxynitride ceramic represents a nitride ceramic containing oxygen. In particular, it is favorable that the ceramic includes crystal grains each having a grain diameter in the range of not less than 100 nm and not more than 1 μm. As a result, it is possible to cause an atomic diffusion self-accelerated state to uniformly occur throughout the entire ceramic by the process to be described later to promote deformation processing.
Step S110: A ceramic is heated within a temperature range of more than 700° C. and not more than 1400° C. In the case where the heating temperature is not more than 700° C., the ceramic does not become an atomic diffusion self-accelerated state, and deformation processing cannot be performed in some cases. In the case where the heating temperature is more than 1400° C., although deformation processing can be performed, a special apparatus such as a high-temperature furnace is required for heating, which is not favorable. More favorably, the ceramic is heated within a temperature range of not less than 800° C. and not more than 1200° C. In this range, it is possible to perform deformation processing on the ceramic at a relatively low temperature. Further favorably, the ceramic is heated within a temperature range of not less than 800° C. and not more than 1000° C. This makes it possible to perform the deformation processing at a low temperature of not more than 1000° C. Therefore, an ordinary furnace can be used, which is industrially advantageous.
Step S120: A voltage is applied to the ceramic heated in Step S110. As a result, the ceramic becomes an atomic diffusion self-accelerated state, and thus deformation processing can be performed. Step S120 is performed simultaneously with Step S110. In this meaning, these Steps may be performed simultaneously by performing Step S120 first and then performing Step S110. The voltage may be a direct current voltage using a direct current power source, or an alternating current voltage using an alternating current power source.
Favorably, a direct current electric field in the range of not less than 50 V/cm and not more than 1500 V/cm is applied to the ceramic. As a result, it is possible to cause the ceramic to be in an atomic diffusion self-accelerated state. In the case of a direct current electric field of less than 50 V/cm, it takes a considerable time (e.g., not less than one minute) to cause the ceramic to be in an atomic diffusion self-accelerated state, which is not realistic. In the case where a direct current electric field of more than 1500 V/cm is applied, there is a possibility that discharge occurs.
More favorably, a direct current electric field in the range of more than 100V/cm and not more than 200V/cm is applied to the ceramic. As a result, it is possible to surely cause the ceramic to be in an atomic diffusion self-accelerated state.
Alternatively, an alternating electric field in the range of not less than 5 V/cm and not more than 200 V/cm may be applied to the ceramic at a frequency in the range of not less than 1 Hz and not more than 60 Hz. As a result, unlike the direct current voltage, it is possible to cause the ceramic to be in an atomic diffusion self-accelerated state even in a small electric field. Further favorably, an alternating electric field in the range of not less than 15 V/cm and not more than 60 V/cm may be applied to the ceramic at a frequency in the range of not less than 3 Hz and not more than 20 Hz. As a result, break strain larger than that in the case of application of a direct current voltage is achieved.
Favorably, a current density in the range of not less than 100 mA/mm2 and not more than 300 mA/mm2 is applied to the ceramic. As a result, it is possible to surely cause the ceramic to be in an atomic diffusion self-accelerated state.
Favorably, a current density in the range of not less than 200 mA/mm2 and not more than 270 mA/mm2 is applied to the ceramic. As a result, a large effect of the atomic diffusion self-accelerated state of the ceramic is achieved, and deformation processing can be performed even in a small deformation stress.
It is favorable to apply a voltage to the ceramic for a time more than zero second and not more than 60 seconds. As a result, it is possible to surely cause the ceramic to be in an atomic diffusion self-accelerated state. Further favorably, the application is performed for not less than five seconds and not more than 20 seconds. As a result, it is possible to cause the ceramic to be in an atomic diffusion self-accelerated state with a relatively low electric field in a short time.
In the step of applying a voltage, it is desired to apply a voltage while controlling the current density so that the stress to be applied to the ceramic is constant in the step (Step S130) of applying a stress, which will be described later. That is, although the current density can change during the deformation processing of the ceramic, by controlling the current density so that the stress is constant, it is possible to perform deformation processing on the ceramic with good controllability. For example, in the case where the stress is a tensile stress, because a current density flowing through the ceramic increases as the deformation processing progresses, it is possible to perform deformation processing on the ceramic with good yield and high precision by appropriately reducing the current density so that the stress is constant. The opposite is true in the case where the stress is a compressive stress.
Step S130: A stress is applied to the ceramic heated in Step S110, to which the voltage has been applied in Step S120. As a result, since the stress is applied to the ceramic that has become an atomic diffusion self-accelerated state through Step S110 and Step S120, which makes it possible to perform deformation processing at a high strain rate, i.e., in a short time. Here, Step S130 is performed simultaneously with Step S110 and S120. As the stress, a stress selected from the group consisting of a tensile stress, a compressive stress, and a bending stress is applied. As a result, it is possible to perform deformation processing on the ceramic to have a desired shape.
Favorably, a stress is applied to the ceramic at a strain rate of not less than 1×10−3s−1 and not more than 1×10−1s−1. By applying a stress at such a high strain rate, it is possible to perform deformation processing in a short time, which is advantageous.
Favorably, a deformation stress in the range of not less than 5 MPa and not more than 150 MPa is applied to the ceramic. In the case of a deformation stress less than 5 MPa, deformation processing is not sufficiently performed on the ceramic in some cases. In the case where the deformation stress exceeds 150 MPa, although deformation processing of the ceramic can be performed, a special apparatus is required. More favorably, a deformation stress in the range of not less than 5 Ma and not more than 15 MPa is applied to the ceramic. This makes it possible to perform deformation processing even with a small deformation stress, which is advantageous.
Steps S110 to S130 are performed in the atmosphere, in vacuum, in an inert gas, or the like. For example, in the case where the ceramic is an oxide, the atmosphere is favorable. In the case where the ceramic is a nitride, vacuum or an inert gas is favorable.
A deformation processing apparatus 200 according to the present invention includes a stress application means 220 on which a ceramic 210 is placed, which applies a stress to the ceramic 210, a heating means 230 that heats the ceramic 210, and a power source 240 that applies a voltage to the ceramic 210. With such a configuration, the method of performing deformation processing on a ceramic according to the present invention described with reference to
The stress application means 220 applies a stress selected from the group consisting of a tensile stress, a compressive stress, and a bending stress to the ceramic 210. The stress application means 220 may include a jig so that the ceramic can be placed thereon.
As the heating means 230, an arbitrary means can be adopted as long as it is capable of heating the ceramic 210 to the temperature in the range of more than 700° C. and not more than 1400° C. Examples thereof include a heating means selected from the group consisting of resistance heating, infrared heating, and combustion heating. An example of the resistance heating is an electric furnace, an example of the infrared heating is an image furnace, and an example of the combustion heating is a gas furnace. These heating means can be readily available, and a deformation processing apparatus can be established.
As the power source 240, a direct current power source capable of applying a direct current electric field of not less than 50 V/cm and not more than 1500 V/cm to the ceramic 210, or an alternating current power source capable of applying an alternating electric field in the range of not less than 5 V/cm and not more than 200 V/cm at a frequency in the range of not less than 1 Hz and not more than 60 Hz is adopted. The power source 240 includes a voltmeter and an ammeter so that values of the voltage and current applied to the ceramic 210 can be measured.
The deformation processing apparatus 200 according to the present invention may further include a control unit (not shown) that controls at least the operation of the power source 240. The control unit controls the operation of the power source 240 to change the current and voltage so that the stress to be applied to the ceramic 210 by the stress application means 220 is constant. Specifically, in the case where the stress application means 220 applies a tensile stress to the ceramic 210, the control unit controls the power source 240 to change the voltage and reduce the current. In the case where the stress application means 220 applies a compressive stress, the opposite control. Alternatively, the control unit may control, on the basis of the amount of strain that has occurred in the ceramic 210 by the stress application means 220, the operation of the power source 240 so that the voltage is constant. In this case, since the amount of strain is calculated, it is possible to perform control with higher precision.
The deformation processing apparatus 200 according to the present invention may be provided in an atmosphere-controllable chamber, or the heating means itself may include a heatable chamber. As a result, it is possible to perform deformation processing on the ceramic 210 not only in the atmosphere but also in vacuum and in an inert gas.
Deformation processing of a ceramic using the deformation processing apparatus 200 according to the present invention will be described. The ceramic 210 on which deformation processing is to be performed by the deformation processing apparatus 200 is placed. Subsequently, the ceramic 210 is heated by a heating means 220 (Step S110 in
Next, the present invention will be described in detail with specific Examples. It should be noted that the present invention is not limited to these Examples.
In Example 1, as a ceramic, 3 mol % Y2O3-stabilized tetragonal ZrO2 polycrystalline body widely used as a ceramic having high strength and toughness was used, and deformation processing was performed in the atmosphere with the heating temperature of 1000° C., various current densities (80, 100, 200, 235, 250, 270, 300 mA/mm2), an initial voltage of 120 V/cm, and a strain rate of 1.0×10−3s−1, 2.0×10−3s−1.
The 3 mol % Y2O3-stabilized tetragonal ZrO2 (Y-TZP) polycrystalline body was obtained by press-molding a 3 mol % Y-TZP powder (manufactured by TOSOH CORPORATION, TZ-3Y grade) manufactured by a hydrolysis method and then sintering it in the atmosphere without pressurization for two hours at 1400° C. The relative density of the Y-TZP polycrystalline body was not less than 95% (Archimedes method), and it was a dense body.
A tensile specimen was obtained by grinding from the Y-TZP polycrystalline body. The tensile specimen is schematically shown in
The specimen had a gauge part length of 12 mm and a cross-sectional dimension of 2.2×2.2 mm2. In order to apply a voltage to the specimen, a hole of φ1 mm to 1.5 mm was opened, and a platinum wire (Pt wire) of φ1 mm to 1.5 mm was passed therethrough.
A deformation processing apparatus 400 included a stress application means 420 on which a tensile specimen 410 was placed, which applied a stress to the tensile specimen 410, a heating means 430 that heated the tensile specimen 410, a power source 440 that applied a voltage to the tensile specimen 410.
The stress application means 420 included a jig 460 that fixed the tensile specimen 410, a load measuring device 470 that measured a stress to be applied to the tensile specimen 410, and a jig driving mechanism 470 that pulled the jig 460.
The heating means 430 was a resistance heating electric furnace. The power source 440 was a high-voltage direct current power source (manufactured by MATSUSADA PRECISION Inc., HAR-3P100), and adopted a control method in which the applied voltage was maintained when the current value is low and the voltage was reduced so as to maintain the current value when it reaches the maximum current. Such a control method was performed by the control unit (not shown).
In the atmosphere, the tensile specimen 410 was heated by the heating means 430 from room temperature to 1000° C. at a heating rate of 10° C. per minute (Step S110 in
The relationship between nominal strain and a deformation stress of the tensile specimen in each current density and strain rate was examined. Here, the values of the current density and the voltage were controlled so that the stress to be applied to the specimen was constant. The results are shown in
In Example 2, the same 3 mol % Y2O3-stabilized tetragonal ZrO2 polycrystalline body as that in Example 1 was used, and deformation processing was performed in the atmosphere with the heating temperature of 800° C., various current densities (160, 220, 235, 250, and 270 mA/mm2), an initial voltage of 190 V/cm, and a strain rate of 1.0×10−3s−1. Other than that, it was the same as in Example 1.
The relationship between nominal strain and a deformation stress of a tensile specimen in each current density and strain rate was examined. The results are shown in
In Example 3, the same 3 mol % Y2O3-stabilized tetragonal ZrO2 polycrystalline body as that in Example 1 was used, and deformation processing was performed in the atmosphere with the heating temperature of 800° C., various current densities (150 and 250 mA/mm2), an initial voltage of 190 V/cm, and a strain rate of 2.0×10−3s−1. Other than that, it was the same as in Example 1.
The relationship between nominal strain and a deformation stress of a tensile specimen in each current density and strain rate was examined. The results are shown in
In Comparative Example 4, the same 3 mol % Y2O3-stabilized tetragonal ZrO2 polycrystalline body as that in Example 1 was used, and deformation processing was performed in the atmosphere with the heating temperature of 1000° C. without applying a voltage. The relationship between nominal strain and a deformation stress of a tensile specimen was examined. The results are shown in
In Comparative Example 5, the same 3 mol % Y2O3-stabilized tetragonal ZrO2 polycrystalline body as that in Example 1 was used, and deformation processing was performed in the atmosphere with the heating temperature of 700° C., a current density of 235 mA/mm2, an initial voltage of 270 V/cm, and a strain rate of 1.0×10−3s−1. Other than that, it was the same as in Example 1. The state after the tensile test was observed. The results are shown in
In Example 6, the same 3 mol % Y2O3-stabilized tetragonal ZrO2 polycrystalline body as that in Example 1 was used and cut out into a rod shape (section of 2.2×2.2 mm2, length of approximately 30 mm), and platinum wires (Pt wire) were attached thereto at intervals of 20 mm, which makes it possible to apply a voltage. The specimen having a rod shape was placed on an electric furnace and heated to 800° C. and 1000° C., and various voltages were applied thereto. After applying the voltage, the time until the current value reaches 250 mA/mm2 (time until it becomes an atomic diffusion self-accelerated state) was examined. The results are shown in
For the sake of simplicity, the experimental conditions (deformation processing conditions) of Examples/Comparative Examples 1 to 6 are shown in Table 1, and the results will be described.
In accordance with
Further, in accordance with
The results were examined in more detail. In accordance with
In accordance with
The results of the tensile test performed on the tensile specimen with the heating temperature of 1000° C., the current density of 250 mA/mm2, and the strain rate of 1.0×10−3s−1 in Example 1 are shown in
The result of the tensile test performed on the tensile specimen with the heating temperature of 700° C., the current density of 235 mA/mm2, and the strain rate of 1.0×10−3s−1 in Comparative Example 5 is shown in
In accordance with the above-mentioned
In
The specimen is a Y-TZP sintered body, as described above. It is known that this material gradually takes ion conductivity from a temperature of not less than 400° C. It is reported that the electrical conductivity thereof is 6.3×100 Ω−1m−1 at 1000° C. (see, for example, M. T. Colomer, et al., J. Solid State. Chem., Vol. 165, 2002, pp. 79-88).
Meanwhile, under a high voltage, it is presumed that electric charges accompanied by point defect are generated and a self-temperature-rise inside the Y-TZP due to Joule heat occurs with the increase in apparent electrical conductivity. As a result, it is presumed that it became a state in which atomic diffusion was self-accelerated much faster than the normal atomic diffusion determined by the temperature, thereby achieving plastic deformation as described above. This is also supported by that fact that the electrical conductivity is increased by 12 times more than the value in Literature. Note that although not shown, an increase in the electrical conductivity was confirmed similarly in other specimens in Example 1 and Example 2.
In
In accordance with
This fact suggests that the atomic diffusion self-acceleration makes it easy to perform deformation processing on a ceramic but in the case where the current density is too large, excessive coarsening of grain size hinders the deformation processing. From this fact, it was also shown that it was favorable to apply a current density in the range of not less than 200 mA/mm2 and not more than 270 mA/mm2 to a ceramic.
In
In accordance with
In Example 6, after applying a voltage, if the current value increased to 250 mA/mm2, it was determined that an atomic diffusion self-accelerated state was reached. On the basis of the results of Example 1, it is possible to reliably obtain plastic deformation with the current density of 250 mA/mm2. Note that it is known that in the case where the atomic diffusion self-accelerated state is not reached, only a current of not more than 15 mA/mm2 flows even when the temperature exceeds 1000° C., and no plastic deformation is obtained.
In accordance with
From this fact, the lower limit of the applied voltage is 50 V/cm. The upper limit is not particularly limited, but 1500 V/cm is appropriate considering discharge and the like. Further, when the application time of the voltage is more than zero second and not more than 60 seconds, the atomic diffusion self-accelerated state is reliably reached. It was shown that the atomic diffusion self-accelerated state could be reached in more than zero second not more than 20 seconds by controlling the heating temperature and the voltage.
In Example 7, as a ceramic, a three-phase (ZrO2-30 vol %, Al2O3-30 vol %, MgAl2O4) composite ceramic material was used, and deformation processing was performed in the atmosphere with the heating temperature of 1000° C., the current density of 50 mA/mm2, the initial voltage of 100 V/cm, and the strain rate of 1.0×10−2s−1.
The three-phase composite ceramic material was obtained by weighing a 3 mol % Y-TZP powder (manufactured by TOSOH CORPORATION, TZ-3Y grade), an Al2O3 powder (manufactured by TAIMEI CHEMICALS Co., Ltd., TM-DAR), and an MgO powder (manufactured by UBE INDUSTRIES, LTD., 100 A) so that the atomic ratio of metal elements satisfiers the above-mentioned composition, press-molding and then sintering them in the atmosphere without pressurization for two hours at 1400° C. The relative density of the sintered body was not less than 95% (Archimedes method), and it was a dense body.
Similarly to Example 1, a tensile specimen was obtained from a sintered body by grinding processing. The specimen had a gauge part length of 12 mm and a cross-sectional dimension of 2.2×2.2 mm2. In order to apply a voltage to the specimen, a hole of φ1 mm to 1.5 mm was opened, and a platinum wire (Pt wire) of φ1 mm to 1.5 mm was passed therethrough.
Using the deformation processing apparatus 400 shown in
In Example 8, a tensile test was performed similarly to Example 6 except that the same three-phase composite ceramic material as that in Example 7 was used and deformation processing was performed with the strain rate of 2.0×10−2s−1. The results are shown in
In Example 9, a tensile test was performed similarly to Example 6 except that the same three-phase composite ceramic material as that in Example 7 was used and deformation processing was performed with the strain rate of 1.0×10−1s−1. The results are shown in
For the sake of simplicity, the experimental conditions (deformation processing conditions) of Examples 7 to 9 are shown in Table 2, and the results will be described.
In accordance with
In Example 10, the same 3 mol % Y2O3-stabilized tetragonal ZrO2 polycrystalline body as that in Example 1 was used, and deformation processing was performed in the atmosphere with the heating temperature of 1000° C., various initial voltages and frequencies (direct current of 120 V/cm, alternating current of 10 Hz-22 V/cm, alternating current of 5 Hz-50 V/cm), the current density of 235 mA/mm2, and the strain rate of 1.0×10−3s−1. Further, in the case of applying an alternating electric field, as the power source 440, an alternating current power source (manufactured by MATSUSADA PRECISION Inc., POP200-1.75) was used. Other than that, it was the same as in Example 1. The relationship between nominal strain and a deformation stress of the tensile specimen in various initial voltages and frequencies was examined. The results are shown in
In Example 11, the same 3 mol % Y2O3-stabilized tetragonal ZrO2 polycrystalline body as that in Example 1 was used, and deformation processing was performed in the atmosphere with the heating temperature of 1000° C., various initial voltages (direct current of 120 V/cm, alternating current of 10 Hz-18 V/cm, alternating current of 10 Hz-29 V/cm, alternating current of 10 Hz-41 V/cm), the current density of 235 mA/mm2, and the strain rate of 2.0×10−3s−1. Further, in the case of applying an alternating electric field, as the power source 440, an alternating current power source similar to that in Example 10 was used. Other than that, it was the same as in Example 1. The relationship between nominal strain and a deformation stress of the tensile specimen in various initial voltages and frequencies was examined. The results are shown in
In accordance with
Since deformation processing can be performed on a dense ceramic material at high speed under the operation condition at a temperature lower than that in the existing one by using the deformation processing method and the deformation processing apparatus according to the present invention, it is favorable for industrial practical use. Further, since special technologies or special apparatuses are not required in deformation processing, it is possible to reduce the cost. The deformation processing method and the deformation processing apparatus according to the present invention can be applied to an arbitrary ceramic material such as an oxide, a nitride, and an oxynitride, and thus is excellent in versatility.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-226977 | Nov 2016 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/040873 | 11/14/2017 | WO | 00 |
