JP4776439B2 - Zirconia sintered body - Google Patents

Description

  The present invention relates to an application to a firing jig mainly used for heat treatment such as firing of electronic material parts. For example, ceramic capacitors, ceramic filters, ceramic resonators, fuel injection injector actuators, and inkjet printer head actuators. Various heat treatments such as firing of piezoelectric elements such as piezoelectric resonators, oscillators, ultrasonic motors, acceleration sensors, knocking sensors, piezoelectric sensors such as AE sensors, baking of electrodes on piezoelectric elements, annealing of lead-containing compounds, etc. It can be applied to jigs that are preferably used in the above.

  Conventionally, products using a piezoelectric ceramic include, for example, an actuator, a filter, a piezoelectric resonator (including an oscillator), an ultrasonic vibrator, an ultrasonic motor, a piezoelectric sensor, and the like.

Among these, actuators have a very high response speed to electrical signals of the order of 10 ⁻⁶ seconds, so they are applied to XY stage positioning actuators for semiconductor manufacturing equipment, ink ejection actuators for inkjet printers, and the like. Yes.

  Piezoelectric ceramics used in such actuators use lead-containing compounds such as lead-containing ceramics such as lead zirconate titanate (hereinafter sometimes simply referred to as PZT). In such a lead compound, since the volatility of lead is high, there is a problem that the composition evaporates from the molded body during firing, causing a composition variation of the sintered body and the composition becomes non-uniform. In particular, the composition variation on the surface of the sintered body was large compared to the inside.

  Therefore, for firing a molded body containing a volatile component such as lead, the composition containing the volatile component contained in the molded body is the same as or similar to that of the molded body. It has been proposed to suppress the evaporation of the components, to suppress the composition fluctuation of the molded body, particularly the composition fluctuation and the structure change in the vicinity of the surface, and to make the characteristics of the sintered body uniform (for example, patent documents). 1).

  In addition, it is proposed that the compact is placed in a dense firing pot and fired in a closed container to suppress evaporation of volatile components and suppress composition fluctuations to homogenize the characteristics of the sintered body. (For example, see Patent Document 2).

  However, even if firing is performed by the method described in Patent Document 1 or Patent Document 2 and volatile components such as lead are prevented from evaporating from the sintered body to the atmosphere during firing, the sintered body contacts during firing. As a result, the surface of the sintered body in contact with the firing jig was changed in composition or changed in structure. In particular, when firing a multilayer body of ceramic green sheets having a thickness of several hundred μm or less, there is a problem that machining is difficult because the thickness is thin even if an altered phase on the surface of the sintered body is to be removed.

  In addition, because the shrinkage varies depending on the site due to compositional variation due to reaction with the firing jig during sintering, deformation such as undulation and warpage occurs, or unevenness is locally generated to obtain a smooth piezoelectric ceramic. There was a problem that was difficult.

  Furthermore, there is a problem that the piezoelectric characteristics vary depending on the site due to compositional variation due to reaction with the firing jig during sintering, and when used in a print head of an ink jet printer, ink discharge variation becomes large, and the image quality is high. There was a problem of lowering.

For this reason, for example, the use of cubic zirconia (ZrO ₂ ) stabilized by CaO or Y ₂ O _{3 having} low reactivity with piezoelectric ceramics as a firing jig is disclosed (for example, see Patent Document 3). ).
Japanese Patent Laid-Open No. 10-29872 FIG. Japanese Patent Laid-Open No. 2004-338777 FIG. JP 2004-315293 A

However, even when cubic zirconia stabilized with CaO or Y ₂ O ₃ is used as a firing jig when firing a molded body containing a lead-containing compound such as PZT, the firing jig and the lead-containing compound such as PZT are used. There was a problem that the lead on the surface of the molded body contained slightly reacted, the composition of the surface of the sintered body in contact with the firing jig became non-uniform, and the characteristics of the PZT sintered body to be fired varied. For example, when PZT is fired as a piezoelectric ceramic, the piezoelectric characteristics of the obtained sintered body vary. Therefore, when a plurality of piezoelectric displacement elements are formed on one piezoelectric ceramic, the piezoelectric characteristics differ among the piezoelectric displacement elements. It was.

  Furthermore, when a molded body containing lead is repeatedly fired using the same firing jig, the reaction with lead on the surface of the firing jig gradually proceeds, the lead content of the firing jig gradually increases, and evaporates from the firing jig. Depending on the firing temperature and the firing temperature range, lead moved from the firing jig to the molded body, and the like, there is a problem that the piezoelectric characteristics of the sintered body vary greatly.

  Accordingly, an object of the present invention is to further reduce the reactivity with a lead compound such as PZT and to obtain a sintered body having a small piezoelectric characteristic variation even when used multiple times for firing a piezoelectric body. It is providing the zirconia sintered compact which prevented reaction with respect to.

The zirconia sintered body of the present invention is a zirconia sintered body having cubic zirconia as a main crystal phase, containing 1 to 14 mol% of CaO and 10 to 16 mol% of Y ₂ O _3, and grain boundaries of zirconia crystals. In which Ca ₃ ZrSi ₂ O ₉ crystals are present and a crystal phase containing Si other than the Ca ₃ ZrSi ₂ O ₉ crystals is substantially absent.

It is preferable that CaZrO ₃ crystals are not substantially present at the grain boundaries of the zirconia crystals.

  The zirconia sintered body of the present invention preferably further contains Pb in a proportion of 0.05 to 10 parts by mass with respect to 100 parts by mass of components other than PbO in terms of PbO.

The present invention finds that the reactivity between Ca ₃ ZrSi ₂ O ₉ crystals and lead is low, and precipitates Ca added as an auxiliary agent at the grain boundaries of zirconia crystals as Ca ₃ ZrSi ₂ O ₉ crystals, This is based on the novel finding that the reaction between the zirconia crystal and the lead-containing compound can be made extremely low.

That is, in the zirconia sintered body having cubic zirconia as the main crystal phase, the zirconia sintered body contains 1 to 14 mol% of CaO and 10 to 16 mol% of Y ₂ O ₃ to control the synthesis temperature of the raw material. by, Si present as an impurity in the grain boundaries of the zirconia crystals of the zirconia sintered body is a part of the less reactive _Ca 3 ZrSi ₂ O ₉ crystal and lead, the _Ca 3 ZrSi the grain boundaries of the zirconia crystals A crystal phase containing Si other than ₂ O ₉ crystal can be substantially absent.

  That is, since there is substantially no Si in a form that easily reacts with lead at the grain boundary of the zirconia crystal, it is possible to prevent lead from reacting along the grain boundary, and the reaction between lead and the zirconia sintered body. Can be significantly reduced.

  Thereby, the reactivity with a lead compound such as PZT is further reduced, and even if the lead compound such as PZT is used multiple times for firing, the variation in the surface composition of the firing jig is reduced. That is, it is possible to provide a zirconia sintered body capable of obtaining a sintered body with small variations in piezoelectric characteristics even when used multiple times for firing the piezoelectric body.

  The case where the zirconia sintered body of the present invention is used as a firing jig for firing lead zirconate titanate (hereinafter referred to as PZT) as a member that prevents reaction with a lead-containing compound will be described as an example. .

  The firing jig in the present invention means a jig used when firing a molded body, and examples include a setter for placing the molded body when firing and a firing bowl for placing the molded body and a setter. it can. In other words, a member that is in direct contact with the molded body, such as a setter, or that reacts or may react with lead vapor evaporated from the molded body, such as a firing bowl, is referred to as a firing jig.

The firing jig of the present invention is composed of a zirconia sintered body having cubic zirconia as a main crystal phase, the zirconia sintered body contains 1 to 14 mol% of CaO and 10 to 16 mol% of Y ₂ O ₃ , It is important that Ca ₃ ZrSi ₂ O ₉ crystals exist in the zirconia grain boundaries of the sintered zirconia, and that there is substantially no crystal phase containing Si other than the Ca ₃ ZrSi ₂ O ₉ crystals. .

The zirconia sintered body contains a Si component as an impurity and exists mainly as ZrSiO _{4 at} the grain boundary of the zirconia crystal. Since ZrSiO ₄ reacts with Pb at 732 ° C. to form a liquid phase, when the zirconia sintered body is used as a firing jig for firing PZT, Pb penetrates into the zirconia sintered body along the grain boundary. As a result, the firing jig and Pb react. At this time, if the reactivity of the zirconia crystal with PZT is high, the permeated Pb further reacts with the zirconia crystal, and the reaction between the firing jig and Pb proceeds quickly.

Even if Si in the zirconia sintered body is about 0.03% by mass in terms of SiO ₂ , the zirconia sintered body becomes Pb as described above while being used multiple times as a firing jig for firing PZT. Reaction, composition variation occurs, and the surface composition of the firing jig becomes non-uniform. If a firing jig having a non-uniform surface composition is used for firing, the characteristics of the PZT sintered body will vary.

According to the present invention, by containing 1 to 14 mol% of CaO and 10 to 16 mol% of Y ₂ O ₃ in the zirconia sintered body, Ca ₃ ZrSi ₂ O ₉ crystals are formed at the grain boundaries of the zirconia crystals. The crystal phase containing Si other than the Ca ₃ ZrSi ₂ O ₉ crystal, particularly ZrSiO _4, can be substantially prevented from being generated. Since the Ca ₃ ZrSi ₂ O ₉ crystal has low reactivity with Pb, Pb can be prevented from penetrating along the grain boundary of the zirconia crystal, and the reaction between the zirconia sintered body and Pb can be suppressed.

When the content of CaO is 1 mol% or more, Si at the grain boundary of the zirconia crystal can be made into a Ca ₃ ZrSi ₂ O ₉ crystal. The desirable content of CaO is particularly 3 mol% or more, and further 4 mol% or more can further suppress the penetration of Pb into the grain boundaries of zirconia crystals. This could not be detected by evaluation by electron diffraction using a TEM (transmission electron microscope), which will be described later, but is presumed to be because ZrSiO ₄ crystals are further reduced.

When the content of CaO is 14 mol% or less, precipitation of CaZrO ₄ at the grain boundaries of the zirconia crystal can be suppressed, and the reactivity between the zirconia crystal and Pb can be lowered. It is estimated that the reason why the reactivity of the zirconia crystal increases when CaZrO ₄ precipitates at the grain boundary of the zirconia crystal is that the amount of Ca in the zirconia crystal decreases and the degree of stabilization of the zirconia crystal decreases.

When the content of Y ₂ O ₃ is 10 mol% or more, when the content of CaO is 1 to 14 mol%, the main crystal phase of the zirconia crystal can be a cubic crystal. Monoclinic zirconia reacts with Pb to produce PbZrO ₃ , and tetragonal zirconia has a lot of room for solid solution of the substance therein, which causes reaction with Pb, but cubic zirconia. Since the reactivity with Pb is low, the reactivity with Pb can be lowered by making the main crystal phase of the zirconia sintered body cubic. Desired content of Y ₂ O ₃ is more by 11 mol% or more.

_Y 2 _{O 3} precipitated at the grain boundary of the crystalline zirconia has a high reactivity with _{Pb, Y} 2 _{O 3} is deposited on the grain boundaries of the zirconia crystals by the content of Y 2 _{O 3} is not more than 16 mol% This can be suppressed. A desirable content of Y ₂ O ₃ is particularly 14 mol% or less, and further 13 mol% or less.

The presence of the Ca ₃ ZrSi ₂ O ₉ crystal at the grain boundary of the zirconia crystal means that the zirconia sintered body is processed into a 0.1 μm thin sample by FIB (focused ion beam), and the grain boundary portion of the zirconia crystal of the sample It can be confirmed by observing (particularly the triple point portion) with a TEM and identifying the crystal phase by electron diffraction.

Further, the fact that a crystal phase containing Si other than the Ca ₃ ZrSi ₂ O ₉ crystal does not substantially exist at the grain boundary of the zirconia crystal is the same as the above in TEM observation, except for the Ca ₃ ZrSi ₂ O ₉ crystal containing Si. This means that there are no diffraction images of crystals, particularly ZrSiO ₄ and SiO ₂ .

In the case of CaZrSi ₂ O ₉ crystal, when Si of impurities contained in the raw material of the zirconia sintered body reacts and precipitates, about 0.01 to 0.1 mass% of Si contained in the zirconia raw material reacts. However, about 1 mol% of SiO ₂ may be added to the raw material of the zirconia sintered body in order to promote the precipitation of CaZrSi ₂ O ₉ crystals.

In the firing jig of the present invention, it is preferable that CaZrO ₃ crystals are not substantially present at the grain boundaries of the zirconia crystals. Here, the fact that CaZrO ₃ crystals are not substantially present at the grain boundaries means that a diffraction image of CaZrO ₃ is not observed by the same TEM observation as described above. By setting the content of CaO to 10 mol% or less, precipitation of CaZrO ₃ crystals at the grain boundaries of zirconia crystals can be suppressed. The desirable content of CaO is particularly 7 mol% or less, and further 6 mol% or less.

In the firing jig of the present invention, the zirconia sintered body preferably contains 0.05 to 10 parts by mass of Pb in terms of PbO with respect to 100 parts by mass of components other than PbO. When firing PZT, when the firing temperature is 1000 ° C. or higher, the amount of the Pb component evaporated from PZT increases rapidly. When a firing jig that has not been used for firing is used, the PZT produced by firing has a Pb component that decreases in characteristics, and the Pb component becomes PbZrO _{3 on} the surface of the firing jig. Adhere. In addition, although it is estimated that the Zr component of PbZrO ₃ is also emitted from PZT, it is not clear whether it is moved by evaporation.

After the firing jig is used several times in firing, the Pb component delivery during firing reaches an equilibrium between PbZrO ₃ and PZT adhering to the surface of the firing jig, so that the characteristics of PZT by firing The fluctuation will disappear. However, PZT produced by the first several firings does not satisfy the electrical characteristics and becomes defective.

  Therefore, by including the Pb component in the firing jig in advance, the Pb component evaporates from the firing jig from the first use of the firing jig, and the evaporation of the Pb component from PZT can be suppressed. , Fluctuations in the characteristics of PZT can be suppressed.

  The Pb component in the firing jig is present at the grain boundary of the zirconia crystal, but there is no other component that reacts particularly in the firing jig. It remains as it is without reacting with. Accordingly, as in the case where the Pb component is not contained, the PZT composition does not react with the PZT component fired by the firing jig, and the PZT characteristics do not vary.

In addition, the Pb component in the firing jig is preferably present in the PZT state at the grain boundary of the zirconia crystal in order to suppress reaction with other components of the firing jig, and further in the PbZrO ₃ state. It is preferable to do so. In order to obtain such a firing jig, Pb may be added as a Pb-containing additive such as PbZrO ₃ or PZT when producing the firing jig. In PZT, the temperature of the calcination process for producing the firing jig or the temperature of the firing process is higher than the temperature of the firing process of PZT. Therefore, in the process of producing the firing jig, the Ti component and zirconia react. PbZrO ₃ is a more preferred Pb-containing additive because there is a fear.

  The higher the PZT firing temperature, the more the Pb component content in the firing jig is preferred. At a firing temperature of 1000 to 1050 ° C., Pb is converted to PbO in an amount of 0.05 to 100 parts by mass other than PbO. It is preferably 2 to 5 parts by mass at 3 parts by mass, 1050 to 1100 ° C., and 4 to 10 parts by mass at 1100 to 1200 ° C. When the Pb component content is higher than the PbT content suitable for the PZT firing temperature shown here, the PZT is used depending on the number of times the firing jig is used when the firing jig is used. There is a risk that the variation in characteristics of the above will increase. In addition, when the Pb component content is low, the number of firings required until stable PZT is obtained compared to the case where the Pb component is not included is reduced, but the PZT property is the first few times. Will fluctuate.

  Furthermore, in the firing at 1000 ° C. or more where the evaporation amount of the Pb component increases, the zirconia sintered body is preferably used as a firing jig as shown in FIG. FIG. 1A is a longitudinal sectional view of the firing jig, and FIG. 1B is a perspective view of the firing jig.

  The firing jig using the zirconia sintered body of the present invention in FIG. 1 is used for firing a powder compact of a metal, alloy, ceramics, or the like containing lead inserted therein. As shown in FIG. 1A and FIG. 1B, the support plate 101, the spacer 102 having the through hole 107 and the top plate 103 are combined to form a space 104 inside, and abut the main surface of the support plate 101. As described above, the molded body 105 is placed in the space 104, and the firing jig is placed in the firing furnace together with the molded body 105 for firing.

  Since the space 104 is separated from the external space, lead volatilized from the molded body 105 can be prevented from coming out of the firing jig, and the amount of lead volatilized from the molded body 105 can be reduced. By reducing the gaps between the firing jigs of the support plate 101, the spacer 102, and the top plate 103, the amount of lead that volatilizes can be further reduced. It should be noted that placing the weight body 106 on the molded body 105 so as to contact the main surface of the molded body 105 can further reduce the volume of the space 104, and the area where the Pb component evaporates from the molded body 105 can be reduced. Smaller and more preferable.

Furthermore, the zirconia crystal of the firing jig of the present invention preferably has a high cubic ratio. The zirconia sintered body having the following cubic ratio _Xc expressed by the diffraction intensity by X-ray diffraction of 0.97 or more can further reduce the reactivity with lead and prevent reaction to lead-containing compounds. When used as a firing jig, it is possible to obtain a sintered body with small variations in characteristics such as piezoelectric characteristics.

In particular, the cubic ratio _Xc of the zirconia sintered body is preferably 0.98 or more, and more preferably 0.99 or more in order to further reduce the reactivity with lead. Zirconia becomes a high-temperature stable phase in the order of monoclinic, tetragonal and cubic crystals.

The cubic ratio _Xc in the present invention can be calculated from the spectrum analysis by X-ray diffraction analysis using the following formulas 1 and 2.

Furthermore, the firing jig of the present invention preferably has no precipitation other than zirconia crystals and Ca ₃ ZrSi ₂ O ₉ crystals. Even when the Pb-containing additive is added for the addition of the Pb component, it is preferable that there is no precipitation other than the crystals of the zirconia crystal, the Ca ₃ ZrSi ₂ O ₉ crystal, and the Pb-containing additive added for the addition of the Pb component. Here, the fact that there is no precipitation of crystals means that, by XRD analysis, when the cubic zirconia main peak intensity is 100, the other diffraction peak intensity is 0.1 or less, and FE-SEM (field emission scanning electron) This means that no precipitated phase is observed when scanning at a magnification of 3000 times using a microscope.

  For example, it is preferable that Al is not substantially contained in the grain boundary of the zirconia main crystal phase. Alumina reacts with Ca precipitated at the grain boundaries to form a compound (hexaluminate) with an Al to Ca ratio of Al / Ca of 6 (hexaluminate), which reacts with lead and leads to an uneven lead content on the zirconia crystal surface. Thus, the amount of lead on the surface of the lead-containing compound in contact with the surface becomes non-uniform.

In the present invention, “substantially not containing Al” means that Al is about 300 ppm or less in terms of alumina (Al ₂ O ₃ ).

  The average crystal particle diameter of the zirconia sintered body is preferably 10 to 40 μm, particularly 25 to 38 μm, and more preferably 30 to 35 μm. As a result, even when repeatedly exposed to high temperatures, creep deformation is unlikely to occur, and thinning is facilitated. In addition, the average crystal particle diameter was measured using SEM (scanning electron microscope).

  The zirconia sintered body as described above can be suitably used as a reaction preventing member for a lead-containing compound, that is, a member for preventing a reaction to a lead-containing compound, and in particular, a Pb atmosphere or a high temperature of 600 ° C. or higher. Since the reaction with the lead-containing compound can be reduced when the heat treatment is performed under the conditions, it can be suitably used as a heat treatment jig having a mounting surface for mounting the lead-containing compound. By using such a firing jig, it is possible to easily produce a homogeneously baked PZT porcelain.

  In particular, when a thin molded body containing lead for producing a piezoelectric ceramic and having a thickness of several hundred μm or less is fired, it is molded even if it is placed on the placement surface of the firing jig and subjected to heat treatment. Since there is substantially no reaction between the body and the firing jig, the piezoelectric ceramic obtained by firing can produce a sintered body with very little warping and waviness.

  It goes without saying that the zirconia sintered body for the lead-containing compound of the present invention can be suitably used not only for firing jigs but also for heat treatment jigs used for heat treatment at 600 ° C. or higher, particularly 700 ° C. or higher, and even 800 ° C. or higher. . For example, in heat treatment such as annealing treatment of lead-containing compounds, reaction treatment such as oxidation and reduction, and bonding treatment, the non-treated material is placed on a setter so as to come into contact with the non-treated material containing the lead-containing compound. Even in the case where the non-processed object is sandwiched between a pair of flat zirconia sintered bodies, the influence of lead, which is a volatile element from the non-processed object, can be reduced during the heat treatment. The object can suppress surface composition fluctuation after heat treatment. In particular, when heat-treating a lead-containing compound at 1000 ° C. or higher, the zirconia sintered body is first treated by heat-treating in a substantially hermetic firing jig using a zirconia sintered body containing Pb. The composition variation of the lead-containing compound can be suppressed from the time of use.

  In particular, a common electrode and a piezoelectric layer are laminated in this order on the diaphragm, a plurality of surface electrodes are formed on the piezoelectric layer, a surface electrode, a common electrode facing the surface electrode, and these electrodes Even if heat treatment is performed on an actuator for a print head of an ink jet printer in which a plurality of piezoelectric displacement elements composed of piezoelectric layers sandwiched between them are formed, variation in displacement between the plurality of piezoelectric elements can be easily controlled. In addition, it is possible to suppress variation in displacement between heat treatment lots of a plurality of times.

  Moreover, since the zirconia sintered body with respect to a lead-containing compound has a high bending strength, the baking jig can be thinned, and the amount of firing can be improved by using multiple layers.

  A method for producing a zirconia sintered body for the lead-containing compound of the present invention will be described below.

  First, raw material powder is prepared. As the zirconia powder, it is preferable to use zirconia powder made of cubic zirconia.

  It is preferable to use a zirconia powder having an average particle size of about 0.1 to 1 μm.

For the addition of the CaO component, CaO powder may be used directly, but CaO may be formed by heat treatment of Ca hydroxide, carbonate or nitrate. The CaO powder is preferably about 0.3 to 1 μm. _Further, Y 2 _{O 3} powder is preferably used having an average particle size of about 0.1 to 1 [mu] m.

The above zirconia powder, additive powder, an organic solvent such as isopropyl alcohol, and zirconia balls are put into a resin pot, mixed and pulverized. The obtained mixed powder is calcined and synthesized to produce a synthetic powder containing zirconia, CaO, and Y ₂ O ₃ . The synthesis temperature of the mixed powder is important to be 1350 ° C. or higher in order to promote the precipitation of Ca ₃ ZrSi ₂ O ₉ crystals in the post-process firing, and the synthesis temperature may be 1350 to 1450 ° C.

  When the Pb component is contained in the zirconia sintered body, it is preferable to lower the firing temperature in the subsequent firing step. Therefore, the synthesis temperature is 1500 to 1600 ° C, particularly 1550 to 1600 ° C. It is preferable that the calcination synthesis is advanced. At this time, since it is difficult to form a mass in the calcined synthetic powder, it is preferable to calcine using microwave heating.

  The obtained synthetic powder is pulverized using zirconia balls until the average particle size is about 0.3 to 0.8 μm. An organic binder and a solvent are mixed with the pulverized raw material powder to produce a slurry, and a green sheet is produced from the obtained slurry by a known molding method such as tape molding, casting molding or injection molding. The obtained green sheet is cut into a desired size, and a plurality of green sheets cut as desired are laminated to produce a molded body. The slurry may be dried to produce a dry raw material, and a molded body having a desired shape may be produced from the dry raw material by a method such as press molding.

When the zirconia sintered body contains a Pb component, Pb may be added as a Pb-containing additive such as PbZrO ₃ or PZT when the slurry is prepared. In this case, the particle diameter of PbZrO ₃ or PZT is preferably 0.5 to 5 μm.

  The obtained molded body is degreased at a desired temperature, for example, 300 to 500 ° C., and then fired at a desired temperature, for example, 1200 to 1700 ° C., particularly 1300 to 1600 ° C., to obtain a zirconia sintered body. Can do.

When the Pb component is contained in the zirconia sintered body, since the Pb-containing additive such as PbZrO ₃ and PZT reacts with zirconia when the firing temperature is high, the firing temperature is 1000 to 1100 ° C., particularly 1000 to 1050. It is preferable to carry out at a temperature as low as ° C.

  A zirconia sintered body was produced as a member in which reaction to the lead-containing compound was prevented.

ZrO ₂ having a crystallization rate of 0.95 or more as a starting material, an additive listed in Table 1 or an additive listed in Table 2 other than a Pb-containing additive, isopropyl alcohol, and a diameter of 2 mm The zirconia balls were put into a resin pot and mixed and pulverized for 16 hours. Thereafter, the powder was put into an alumina crucible having a purity of 99.9%, and calcined at the synthesis temperature shown in Tables 1 and 2 for 2 hours to produce a synthetic powder. The samples listed in Table 2 were calcined by microwave heating. The synthetic powder was pulverized for 20 hours using a zirconia ball having a diameter of 2 mm, the Pb-containing additive shown in Table 2 was added to the sample shown in Table 2, and 5 wt% of paraffin wax was added to the obtained powder. Granulated through 40 nylon meshes. In addition, the addition amount of Pb containing additive of Table 2 is a mass part with respect to 100 mass parts of synthetic powders after calcination. After granulation, it was press-molded into 30 mm × 20 mm × 2 mm. The molded body was debindered at 400 ° C. for 2 hours, and then fired at 1550 ° C. for 2 hours in the air for the samples listed in Table 1, and 1030 ° C. in the air for the samples listed in Table 2. Baking was performed for 2 hours to obtain a zirconia sintered body.

The obtained zirconia sintered body was subjected to composition analysis by fluorescent X-ray analysis. For quantitative analysis, a calibration curve using ZrO ₂ , CaO, and Y ₂ O ₃ was prepared in advance, and the calibration curve was used.

  The crystal grain size of the zirconia sintered body was measured using SEM.

  Moreover, about the zirconia sintered compact used by the following reaction test, surface processing was performed so that surface roughness Ra might be set to 0.01-0.05.

  Next, the produced zirconia sintered body was evaluated.

Evaluation is made of Pb _0.92 Sr _0.06 Ba _0.02 (Zn _1/3 Sb _2/3 ) _0.075 (Ni _1/2 Te _1/2 ) _0.005 Zr _0.44 Ti as a lead-containing compound. PZT (modified PZT) represented by _0.48 O ₃ was fired.

First, PbO, SrCO ₃ , BaCO ₃ , ZnO, Sb ₂ O ₃ , NiO, TeO ₂ , ZrO ₂ and TiO ₂ each having a purity of 99% or more were prepared as raw materials for lead-containing compounds, and these were wet mixed Thereafter, the resultant was calcined at a temperature of slightly over 900 ° C. to produce a ceramic material powder for piezoelectric use.

  The green sheet is made by adding a functional group to butyl methacrylate as a water-based binder and making it water-soluble to the above-mentioned piezoelectric ceramic powder, a polycarboxylic acid ammonium salt as a dispersant, isopropyl alcohol and pure water as a solvent, Each was added and mixed to prepare a slurry, and this slurry was formed into a sheet shape having a thickness of about 30 μm on a carrier film by a doctor blade method.

  Similarly, green sheets were prepared using various piezoelectric ceramic powders. Also, an internal electrode paste was prepared. The obtained internal electrode paste was printed on the surface of the green sheet with a thickness of 4 μm to form an internal electrode. Further, one green sheet on which the internal electrode paste was not printed was laminated between the two green sheets with the surface on which the internal electrodes were printed facing upward, and was pressed under pressure to produce a laminated molded body for a reaction test.

  Further, in the same process, a laminated molded body for measuring electrical characteristics was prepared that does not include electrodes having a size of 1 mm in thickness, 3 mm in width, and 12 mm in length after firing.

  Next, the zirconia sintered body having the composition shown in Table 1 was evaluated.

The X-ray diffraction spectrum of the surface of the zirconia sintered body was evaluated, and _Xc was calculated using the above formulas 1 and 2.

  The presence or absence of a grain boundary precipitated phase was also confirmed by X-ray diffraction spectrum and FE-SEM.

  Next, the sintered zirconia having the composition shown in Table 1 was fired once, five times, ten times, 50 times, 100 times and 500 times, and then the presence or absence of reaction with Pb was confirmed. Firing is performed by degreasing the produced laminated laminate for reaction test, and then placed in a firing furnace so that the laminated molded body is sandwiched between zirconia sintered bodies having the composition shown in Table 1, and this is placed at 900 ° C., oxygen This was carried out by maintaining and firing in an atmosphere of 99% or more for 2 hours to produce a reaction test laminate comprising a piezoelectric vibration layer and internal electrodes.

  In addition, the presence or absence of reaction investigated the reaction of the surface of a zirconia sintered compact, and penetration of Pb to the grain boundary of a zirconia crystal. For surface reaction, the surface of the zirconia sintered body in contact with the lead-containing compound is subjected to surface analysis by SEM EDS (energy dispersion analysis) to detect lead. If it is detected, x, if not detected Is marked as ○. The penetration of Pb was performed by processing the firing jig into a 0.1 μm thin sample by FIB, observing the grain boundary part of the zirconia crystal at a part of 20 μm from the surface in contact with the laminated molded body in the longitudinal section by TEM When Pb was detected in the analysis, it was indicated as x, and when it was not detected, it was indicated as ◯.

If a reaction with Pb was detected both in the surface reaction and in the evaluation of Pb penetration, the firing evaluation of the sample was stopped at that time. When the reaction with Pb is detected by either the surface reaction or the evaluation of the penetration of Pb, the subsequent evaluation with the detection of the reaction with Pb is not performed, and the evaluation with no detection of the reaction between the firing and the Pb is performed. It was. The results are shown in Table 1.

Sample No. of the present invention. In Nos. 3 to 9, 12 to 15, 21 and 22, neither surface reaction nor Pb infiltration was observed even when firing was performed at least 50 times, and reaction with the laminated molded body was suppressed. Sample No. in which no CaZrO ₃ crystal was detected at the grain boundary of the zirconia crystal. In Nos. 3 to 7, neither the reaction on the surface nor the penetration of Pb could be observed even when firing was performed at least 100 times, and the reaction with the laminated molded body for reaction test was further suppressed.

On the other hand, sample No. 4 outside the scope of the present invention, in which ZrSiO ₄ crystal, which is a crystal containing Si other than Ca ₃ ZrSi ₂ O ₉ crystal, is precipitated at the grain boundary of zirconia crystal. In 1, 2, 17-20 and 23-26, Pb penetration was observed from the first firing. In addition, Sample No. with a Y ₂ O ₃ content of more than 16 mol% was obtained. In 16, 27 and 28, Y ₂ O ₃ crystals were precipitated at the grain boundaries of the zirconia crystals, and surface reactions were observed from the first firing. Furthermore, the sample No. _{2 with} a Y ₂ O ₃ content of less than 10 mol% was used. In 11 and 29 to 32, the zirconia crystal was not sufficiently stabilized, and surface reaction was observed in the 50th and subsequent firings. Furthermore, Sample No. with a CaO content of more than 14 mol%. In 10, 31, and 32, the zirconia crystals were not sufficiently stabilized, and surface reaction was observed in the 10th and subsequent firings.

  Next, the sintered zirconia having the composition shown in Table 2 was fired once, five times, ten times, 50 times, 100 times, and 500 times, and then the presence or absence of reaction with Pb was confirmed. Firing is performed by degreasing the produced reaction test laminate and then placing the reaction test laminate on a zirconia sintered body having the composition shown in Table 2 as shown in FIG. This was held in an atmosphere of 1030 ° C. and oxygen 99% or more for 2 hours and fired to produce a reaction test laminate comprising a piezoelectric vibration layer and internal electrodes. Specifically, the mounting of the reaction test laminated molded body on the zirconia sintered body is performed by combining the support plate 101, the spacer 102, and the top plate 103 to form a space 104 inside the support plate 101. The reaction test laminate molded body 105 was placed in the sealed space 104 so as to be in contact with the main surface, and the weight body 107 was placed on and sandwiched between the reaction test laminate molded bodies.

  Elemental analysis was performed using a WDS-EPMA (Electron Probe Microanalyzer with Wavelength Dispersion Spectrometer) in a 200 μm × 200 μm area of the zirconia sintered body in contact with PZT, and the Pb content was measured. This measurement was performed at five arbitrary points to obtain an average value, which was converted into a PbO amount, and a PbO content was obtained.

In addition, the presence or absence of reaction investigated the reaction of the surface of a zirconia sintered compact, and penetration of Pb to the grain boundary of a zirconia crystal. In firing at 1030 ° C. with PZT in the sealed space 104, PbZrO ₃ adheres to the surface of the zirconia sintered body inside the sealed space 104, so the zirconia sintered body is not assembled before evaluating the surface reaction. In this state, heat treatment was performed in the air at 1100 ° C. for 3 hours to burn off the PbZrO ₃ adhering to the surface. Since this burning-out process is necessary for the evaluation, zirconia sintered bodies were prepared and evaluated according to the number of firings to be tested from the beginning.

  As for the reaction on the surface, the surface of the zirconia sintered body in contact with the lead-containing compound was examined by TEM EDS analysis for an increase in the Pb content at the grain boundary portion of the zirconia crystal. Specifically, the amount of Pb and the amount of Zr were measured at the grain boundary portion of the zirconia crystal, the amount of Pb / Zr was calculated from the result, and the change in this value was measured. When it becomes 1.02 times or more with respect to the Pb amount / Zr amount of the zirconia sintered body before being used for firing, the reaction between the zirconia sintered body and Pb caused an increase in Pb. When it was less than 02, it was displayed as ◯. The calculation of the Pb amount / Zr amount was performed using a calibration curve prepared in advance from a plurality of samples having different Pb amounts / Zr amounts. The penetration of Pb is achieved by processing the firing jig with a FIB into a 0.1 μm thin sample perpendicular to the surface in contact with the laminated molded body, and the grain boundary portion of the zirconia crystal at a portion of 20 μm from the surface in contact with the laminated molded body in cross section. The same evaluation was performed by EDS analysis of TEM.

If a reaction with Pb was detected both in the surface reaction and in the evaluation of Pb penetration, the firing evaluation of the sample was stopped at that time. When the reaction with Pb is detected by either the surface reaction or the evaluation of the penetration of Pb, the subsequent evaluation with the detection of the reaction with Pb is not performed, and the evaluation with no detection of the reaction between the firing and the Pb is performed. It was. The results are shown in Table 2.

Sample No. of the present invention. In 35 to 37, 40, 41 and 43 to 63, neither surface reaction nor Pb infiltration was observed even when firing was performed at least 50 times, and reaction with the laminated molded body was suppressed. Sample No. in which no CaZrO ₃ crystal was detected at the grain boundary of the zirconia crystal. 35, 36, 40, 41, and 43 to 63, neither surface reaction nor Pb infiltration was observed even after firing at least 100 times, and the reaction with the laminate for reaction test was further suppressed. It was.

On the other hand, sample No. 4 outside the scope of the present invention, in which ZrSiO ₄ crystal, which is a crystal containing Si other than Ca ₃ ZrSi ₂ O ₉ crystal, is precipitated at the grain boundary of zirconia crystal. In 33 and 34, Pb infiltration was observed from the first firing. In addition, Sample No. with a Y ₂ O ₃ content of more than 16 mol% was obtained. In No. 42, Y ₂ O ₃ crystals were precipitated at the grain boundaries of the zirconia crystals, and surface reactions were observed from the first firing. Furthermore, the sample No. _{2 with} a Y ₂ O ₃ content of less than 10 mol% was used. In No. 39, the zirconia crystal was not sufficiently stabilized, and a surface reaction was observed after the 50th firing. Furthermore, Sample No. with a CaO content of more than 14 mol%. In No. 38, the zirconia crystals were not sufficiently stabilized, and surface reaction was observed in the 10th and subsequent firings.

  Further, for some of the samples described in Tables 1 and 2, after firing 1, 3, 5, 7 and 9 times, the piezoelectric properties of the fired PZT were measured, and zirconia sintered The number of times from the start of use of the body until stable PZT was obtained was evaluated. Firing is performed by degreasing the produced laminate for electrical property measurement, placing the laminate for electrical property measurement on a zirconia sintered body as shown in FIG. 1, and placing it in a firing furnace. The firing was carried out by holding for 2 hours in an atmosphere containing the firing temperature and oxygen of 99% or more shown in Table 3 to produce a laminate for measuring electrical characteristics.

The laminate for electrical property measurement was baked with silver electrodes on both sides and subjected to polarization treatment by applying a direct voltage of 3 kV / mm for 30 minutes in silicon oil at 80 ° C. to obtain a sample for electrical property measurement. In the sample for measuring electrical characteristics, the piezoelectric strain constant D ₃₁ and the electromechanical coupling coefficient K ₃₁ were measured based on the electrical industry association standard EMAS-6100 with respect to the longitudinal vibration mode of the short plate-like vibrator. With respect to the measurement results of D ₃₁ and K ₃₁ , those having a small difference from the characteristics stably obtained after the ninth firing were assumed to have been fired without changing the characteristics. Specifically, it was assumed that a D ₃₁ measurement result in the range of 190 to 208 pC / N and a K ₃₁ measurement result in the range of 30 to 35% could be fired without changing the characteristics. The results are shown in Table 3.

  Among the samples of the present invention, Sample No. which does not contain Pb. Sample No. 5 and Pb content is 0.05 parts by mass or less with respect to 100 parts by mass of components other than PbO in terms of PbO. In No. 43, when the firing temperature of PZT is 950 ° C. or lower, PZT having no characteristic variation is obtained from the first firing, but the firing until the PZT having no characteristic variation is increased as the firing temperature is increased. In the case where the firing temperature was 1200 ° C., PZT having no characteristic fluctuation was obtained after the seventh firing. In contrast, in the sample of the present invention, the content of Pb was 0.05 parts by mass with respect to 100 parts by mass of components other than PbO in terms of PbO. In 44 and 55, even when the firing temperature of PZT was 1000 ° C. and 1050 ° C., PZT having no characteristic variation was obtained from the first firing. As the Pb content increases, PZT having no characteristic fluctuation can be obtained by firing a small number of times. In the sample of the present invention, the Pb content is a component other than PbO in terms of PbO. Sample No. which is 9.9 parts by mass with respect to 100 parts by mass. In No. 49, when the firing temperature of PZT was 1000 ° C. to 1200 ° C., PZT having no characteristic variation was obtained from the first firing.

It is a baking jig | tool using the zirconia sintered compact with respect to the lead containing compound of this invention, (a) is a longitudinal cross-sectional view, (b) is a perspective view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Support plate 102 ... Spacer 103 ... Top plate 104 ... Space 105 ... Molded body 106 ... Weight body 107 ... Through-hole

Claims (3)

A zirconia sintered body having cubic zirconia as a main crystal phase, which prevents reaction with respect to a lead-containing compound, containing 1 to 14 mol% of CaO and 10 to 16 mol% of Y ₂ O _3, and grain boundaries of zirconia crystals A zirconia sintered body characterized in that a Ca ₃ ZrSi ₂ O ₉ crystal is present and a crystal phase containing Si other than the Ca ₃ ZrSi ₂ O ₉ crystal is substantially absent. 2. The zirconia sintered body according to claim 1, wherein CaZrO ₃ crystals are substantially absent from grain boundaries of the zirconia crystals. ₃ . The zirconia sintered body according to claim 1 or 2, further comprising Pb in a ratio of 0.05 to 10 parts by mass with respect to 100 parts by mass of components other than PbO in terms of PbO.

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