JP5116246B2 - Ceramic blade and method for manufacturing the same - Google Patents

Description

  The present invention relates to a ceramic blade such as a kitchen knife and scissors using a zirconia sintered body having high strength, high toughness and high corrosion resistance, and a method for producing the same.

ZrO ₂ in the zirconia sintered body undergoes phase transformation from cubic crystal, which is a stable phase, to tetragonal crystal, which is a stable phase, and to monoclinic crystal at normal temperature, with cooling after firing. In particular, during the transformation from tetragonal to monoclinic, the volume expands, and as a result, the zirconia sintered body is destroyed. Therefore, stabilized zirconia in which a stabilizer such as Y ₂ O ₃ , MgO, CaO and CeO ₂ is dissolved in ZrO ₂ to maintain a cubic structure of a stable phase or a tetragonal structure of a metastable phase even at room temperature. High quality sintered bodies are mainly used for ceramic members that require high strength and high toughness.

In general, Y ₂ O ₃ is mainly used as such a stabilizer, and the amount added to ZrO _{2 as} the main component is 3 mol% or more at which the crystal structure of ZrO ₂ is further stabilized. At present, the added zirconia sintered body is used for various purposes. Here, the reason why a zirconia sintered body to which 3 mol% or more of Y ₂ O ₃ is added as a stabilizer is used is that the crystal phase of the zirconia sintered body is stabilized at an addition amount of less than 3 mol%. This is because a monoclinic crystal structure is precipitated in the main component zirconia crystal and it is difficult to obtain a good sintered body.

However, when the amount of Y ₂ O ₃ added is increased to 3 mol% or more at which the crystal structure of the zirconia sintered body is stabilized, mechanical properties such as strength and fracture toughness are lowered. This is because the residual portion of Y ₂ O ₃ added as a stabilizer that could not be completely dissolved is precipitated at the zirconia crystal grain boundaries and the like, so to speak, has the same effect as the inevitable impurities on the sintered body. Of various uses, when using zirconia sintered bodies for consumer and industrial blades, zirconia sintered with improved fracture toughness to eliminate the cutting edge as well as strength. Body demand is high. So far, zirconia sintered bodies to which 3 mol% or more of the above-mentioned Y ₂ O ₃ stabilizer has been added have been used, but if 3 mol% or more is added, the crystal structure is stabilized. In recent years, attempts have been made to reduce the amount of Y ₂ O ₃ added as a stabilizer.

On the other hand, the amount of Y ₂ O ₃ added as a stabilizer is less than 3 mol%, and further, SiO ₂ , Al ₂ O ₃ , MgO, CaO, or the like is added as a sintering aid, so that There is also a zirconia sintered body aiming at further improvement of mechanical properties by improving the binding property.

For example, in Patent Document 1, the zirconia sintered body contains an Al ₂ O ₃ component together with an SiO ₂ component or an SiO ₂ component, and at least one transition metal oxide is contained, and the entire crystal grain boundary is contained. It has been proposed that a zirconia sintered body in which a vitreous phase mainly composed of SiO ₂ is formed is used to reduce strength variation with high strength.

In Patent Document 2, ZrO ₂ is the main component, Y ₂ O ₃ is 4 to 7% by mass, Al ₂ O ₃ is 0.1 to 0.4% by mass, and SiO ₂ is 0.005 to 0.1%. There is a description that a zirconia sintered body containing mass% is used as an optical connector member.

Further, Patent Document 3 discloses that Y ₂ O ₃ / ZrO ₂ molar ratio is 1.5 / 98.5 to 4/96, SiO ₂ content is 0.05 to 2.5% by mass, and Al ₂ O _{3 is} contained. There is a description that it is a zirconia sintered body mainly composed of tetragonal crystals added in an amount of 0.05 to 3.0% by mass and used as a member for a pulverizer / disperser.

Patent Document 4 describes that the zirconia sintered body described in Patent Document 3 is used for bearings. Patent Document 5 describes that the content of SiO ₂ is less than 0.05% by mass, and the amount of SiO ₂ present at the grain boundary of the zirconia sintered body is reduced to improve the corrosion resistance.
Japanese Patent Laid-Open No. 04-209761 JP 2003-73165 A JP 2003-128461 A JP 2003-314556 A Japanese Patent No. 2762495

Zirconia sintered body of these described in Patent Documents 1 to 4, Y ₂ O ₃ added amount includes an area less than 3 mol% both in terms of mole percent, when its area, It is considered that mechanical properties such as fracture toughness are improved as compared with the zirconia sintered body in which Y ₂ O _{3 is} added in an amount of 3 mol% or more, and it can be sufficiently applied as the aforementioned blade.

However, when the zirconia sintered body described in Patent Documents 1 to 4 is used for a knife, as described in Patent Document 1, a vitreous phase is formed at a zirconia grain boundary, If used, the acid component contained in food or the like is corroded by acid or hydrofluoric acid or the like, and the vitreous phase composed of SiO ₂ at the grain boundary is corroded, so that its corrosion resistance becomes a problem. . In particular, as described in Patent Document 1, when a vitreous phase is present over the entire grain boundary, there is a portion in which the vitreous phase is continuously formed, and zirconia crystals and vitreous are present. Since it is considered that there is a portion joined by the phase, the zirconia crystal is severely grained when the vitreous phase portion is corroded.

For this problem, Patent Document 5 describes that the content of SiO ₂ is less than 0.05% by mass, and the amount of SiO ₂ present at the grain boundaries of the zirconia sintered body is reduced to improve the corrosion resistance. However, since the zirconia sintered body described in Patent Document 5 contains a CaO component, and this CaO component is also present at the grain boundary of the zirconia sintered body in the same manner as SiO ₂ , this is used for consumer use or When used as an industrial blade member, there is a risk that CaO is corroded by the chlorine component contained in water, and the corrosion resistance is significantly reduced.

Thus, with respect to the added conventional zirconia sintered body 3 mol% or more Y ₂ O ₃ as a stabilizer, suppresses the Y ₂ O ₃ amount to an amount smaller than 3 mol%, the mechanical properties Even in a zirconia sintered body that is improved in quality, if the crystal grain boundary contains SiO ₂ and CaO, when this is used as a blade, the grain boundary SiO ₂ component and CaO component are different for each use environment. There is a problem in that it cannot be used due to chipping of the cutting edge or a decrease in the overall strength due to corrosion by the corrosive components present in the steel, and zirconia crystals that have fallen after long-term use. Accordingly, an object of the present invention is to provide a ceramic blade having excellent corrosion resistance and good strength, and a method for producing the same.

As a result of intensive studies in view of the above situation, the present inventors have found the following findings and have completed the present invention. That is, as in the production method according to the present invention, granulation obtained by mixing and granulating ZrO ₂ powder stabilized with Y ₂ O ₃ of 0.05 μm or more and 0.2 μm or less and SiO ₂ sol. After molding using powder, in the firing furnace, the gas pressure is set higher than atmospheric pressure, the maximum firing temperature is 1300 ° C or higher and 1500 ° C or lower, and the temperature decreasing rate is 120 ° C / h from the maximum firing temperature to 100 ° C. When firing at 200 ° C./h or less above, the gas pressure in the firing furnace was made higher than atmospheric pressure, so that it could not be completely dissolved in an additive such as Si having a melting point lower than ZrO ₂ and zirconia crystals. Y ₂ O ₃ can be moved to the grain boundary of the zirconia sintered body. In addition, by using ultrafine SiO ₂ sol particles, it can be made to easily exist at the grain boundaries of zirconia crystals, and further, the whole grains are baked at a maximum temperature of 1300 ° C. or higher and 1500 ° C. or higher. It is possible to make the SiO ₂ component exist in at least 80% or more of the boundary. Also the cooling rate 120 ° C. / h or more, may be present SiO ₂ component of the grain boundary as an amorphous by and to 200 ° C. / h or less.

In the zirconia sintered body to which Y ₂ O ₃ produced under the above-mentioned conditions is added as a stabilizer, the mass ratio of Y element to 0.1 mass% of the amorphous phase existing at the grain boundary is 0.1. It is in the range of not less than 10% by mass and not more than 10% by mass. Due to the presence of such a proportion of Y element at the grain boundary, Y ₂ O ₃ has higher corrosion resistance characteristics than conventional zirconia sintered bodies, and has corrosion resistance against corrosive solutions and the like. In particular, the corrosion resistance at high temperatures can be improved.

  Therefore, the first invention of the present invention comprises a zirconia sintered body having a crystal phase comprising a zirconia crystal as a main component and an amorphous phase containing a Y element and a Si element at the grain boundary. The ceramic blade is characterized in that the mass ratio of Y element to 100 mass% of the amorphous phase is 0.1 mass% or more and 10 mass% or less. The mass ratio of the Y element in the amorphous phase containing Y and Si elements existing at the grain boundaries of the zirconia sintered body constituting the ceramic blade is 0.1% by mass or more and 10% by mass or less. By setting it as the range, the corrosion resistance against corrosive solutions such as chlorine components contained in tap water is improved, and the life of the ceramic blade can be extended.

The ceramic blade according to the present invention has a crystalline phase composed of yttria (Y ₂ O ₃ ) or silica (SiO ₂ ) crystals. In addition to the crystal phase and amorphous phase consisting of the zirconia crystal, it has a crystal phase consisting of yttria (Y ₂ O ₃ ) or silica (SiO ₂ ) crystal, thereby preventing the development of cracks occurring at the grain boundaries. Therefore, mechanical strength such as fracture toughness of the ceramic blade is improved.

The ceramic blade according to the present invention is characterized in that a mass ratio of Si element to 100 mass% of the amorphous phase is 0.1 mass% or more and 10 mass% or less. As the ceramic blade, a zirconia sintered body to which 3 mol% of Y ₂ O ₃ stabilizer has been added has been used in the past, but in the present invention, the amount of Y ₂ O ₃ stabilizer is particularly 2 mol. % Can also improve the mechanical strength. However, when the amount of the stabilizer is reduced, the zirconia sintered body is not sufficiently stabilized, so that although the absolute value of the mechanical strength is high, the variation becomes large and becomes a problem. Therefore, in the present invention, an amorphous phase containing Si and Y elements is present in the zirconia crystal grain boundary of the zirconia-based sintered body, and the mass ratio of Y and Si elements in the amorphous phase varies in strength. By making it within the range of 0.1% by mass or more and 10% by mass or less, variations in mechanical strength can be suppressed.

In the ceramic blade according to the present invention, the zirconia sintered body contains 95% by mass or more of ZrO ₂ . When the zirconia sintered body contains 95% by mass or more of ZrO ₂ , mechanical properties can be improved.

The ceramic blade according to the present invention is characterized in that the zirconia sintered body contains 0.05 mass% or more and 0.40 mass% or less of Si in terms of SiO ₂ . By setting Si as a metal element contained in the zirconia sintered body to 0.05 mass% or more and 0.4 mass% or less in terms of SiO ₂ , and making the abundance ratio of Y in the above range, corrosion resistance and machine A ceramic blade with excellent mechanical properties can be obtained.

  The ceramic blade according to the present invention is characterized in that the Y mass ratio and the Si mass ratio are calculated from an element count by energy dispersive X-ray spectroscopic analysis. By calculating from the element count by energy dispersive X-ray spectroscopic analysis, it is possible to perform highly accurate measurement.

  The ceramic blade according to the present invention is characterized in that an average crystal grain size of zirconia crystals in the zirconia sintered body is 0.3 μm or more and 0.5 μm or less. By setting the average crystal grain size of the main crystal to 0.3 μm or more and 0.5 μm or less, fracture toughness can be improved, and further, a decrease in strength after long-term use can be suppressed.

The ceramic blade according to the present invention is characterized in that the zirconia sintered body has a bulk density of 6.03 g / cm ³ or more and a relative density of 99% or more. Thus, since the bulk density of the zirconia sintered body is 6.03 g / cm ³ or more and the relative density is 99% or more, the mechanical properties are excellent.

The second invention of the present invention includes a step of obtaining a granulated powder obtained by mixing ZrO ₂ powder stabilized with Y ₂ O ₃ and SiO ₂ sol, and granulating the granulated powder, and molding the granulated powder into a blade shape. A step of obtaining a molded product, and a temperature reduction rate from the highest temperature to 100 ° C. at a maximum firing temperature of 1300 ° C. or more and 1500 ° C. or less in a firing furnace under a gas pressure greater than atmospheric pressure. A method for producing a ceramic blade characterized by comprising a step of obtaining a sintered body fired at 120 ° C./h to 200 ° C./h and a step of grinding the sintered body. . By using ultrafine SiO ₂ sol particles, it can be easily present at the grain boundaries of zirconia crystals. Furthermore, by baking at a maximum temperature of 1300 ° C. or more and 1500 ° C. or less under a gas pressure of atmospheric pressure or higher, it is possible to make the SiO ₂ component present in at least 80% or more of all grain boundaries. Further, by setting the temperature lowering rate to 120 ° C./h or more and 200 ° C./h or less, the SiO ₂ component at the grain boundary can be present as amorphous.

The method for producing a ceramic blade according to the present invention is characterized in that the ZrO ₂ powder stabilized by Y ₂ O ₃ has a particle size of 0.05 μm or more and 0.2 μm or less. By using fine particles in the range of 0.05 μm or more and 0.2 μm or less in the ZrO ₂ powder stabilized by Y ₂ O ₃ and controlling the particle size distribution, it becomes possible to sinter at a lower temperature than before, and the production cost is reduced. It becomes possible to reduce.

In the method for producing a ceramic blade according to the present invention, the granulated powder has an average particle size (D ₅₀ ) of 40 μm or more and 55 μm or less, and a particle size width (D _{10 to} D ₉₀ ) of 20 μm or more, and It is 130 μm or less. When such granulated powder is used, a ceramic blade with higher strength can be obtained.

  The ceramic blade according to the present invention includes those manufactured by a method other than the above-described method for manufacturing a ceramic blade, and is not limited to the above-described manufacturing method.

According to the present invention, Y ₂ O remaining without acting as a stabilizer can be obtained by setting the Y mass ratio of an arbitrary grain boundary of the zirconia sintered body to 0.1 mass% or more and 10 mass% or less. It is possible to suppress the _three components from gathering at the grain boundary and causing a decrease in mechanical properties. Furthermore, Y ₂ O ₃ has a high corrosion resistance characteristic as compared with a conventional zirconia sintered body as a glass layer made of only SiO ₂ by allowing a small amount of Y element to exist in the grain boundary. Corrosion resistance against a corrosive solution or the like can be improved. In particular, the corrosion resistance at high temperatures can be improved.

(Manufacturing method of ceramic blade)
It shows about the manufacturing method of the zirconia sintered compact used for the ceramic blade of this invention.

In the ZrO ₂ powder stabilized by Y ₂ O ₃ used for the production of the zirconia sintered body of the present invention, the content of ZrO ₂ and Y ₂ O ₃ as a stabilizer becomes a predetermined molar ratio. Thus, a zirconium compound aqueous solution and a stabilizer compound aqueous solution are mixed. As such a zirconium compound, for example, zirconium oxychloride can be suitably used, and as a stabilizer compound, for example, yttrium oxychloride can be suitably used. Then, after producing a slurry using a coprecipitation method for obtaining a hydrate by hydrolysis, dehydration, drying, and calcining at 500 to 1200 ° C. to obtain a calcined powder, the obtained calcined powder The body is obtained by pulverizing the body with a ball mill or the like by a wet method and drying it.

Note that additives other than stabilizer such aforementioned Y ₂ O _3, the may be added in the form of such conventional oxide during pulverization of the calcined powder. Further, if the particle size of the ZrO ₂ powder stabilized by Y ₂ O ₃ is 0.05 μm or more and 0.2 μm or less, the crystals of the sintered body are refined to have high strength and high toughness. In addition, if the particle size is 0.05 μm or more and 0.1 μm or less, the mechanical properties of the sintered body become higher, which is more preferable.

Next, a granulated powder is obtained by adding a SiO ₂ sol and an organic binder to the ZrO ₂ powder stabilized with Y ₂ O ₃ , kneading and drying and granulating. Then, the obtained granulated powder is filled into, for example, a die of a blade and pressure-molded to produce a molded body. The average particle size (D ₅₀ ) of the granulated powder may be 40 μm or more and 55 μm or less, and when the particle size width (D _{10 to} D ₉₀ ) is 20 μm or more and 130 μm or less, higher strength zirconia. It is possible to obtain a quality sintered body. Here, if the average particle size (D ₅₀ ) is smaller than 40 μm, the granulated powder is fine and the flow to the mold or the like is poor, so the filling property at the time of molding becomes low, and the part tends to become a defect. On the other hand, if it is larger than 55 μm, for example, the granulated powder is badly crushed when it is press-molded, resulting in a defect, and the strength of the blade is significantly lowered, which is not suitable. Further, when the particle size width (D _{10 to} D ₉₀ ) is outside the range of 20 μm or more and 130 μm or less, the variation in strength becomes large, which is not suitable for a ceramic blade.

Moreover, as a granulation method, in order to improve mass-productivity, it is preferable to granulate using a spray dryer. Further, the molding method and conditions are not particularly limited, and methods such as press molding, CIP molding (rubber press), cast molding, extrusion molding, and injection molding are employed. For the molding raw material, if necessary, for example, PVA (polyvinyl alcohol) -based, acrylic resin-based, wax-based, cellulose-based water-soluble polymers, polystyrene, polypropylene and other thermoplastic resins, lubricants, You may mix | blend a mold release agent, a plasticizer, water, etc. For example, in press molding, in order to prevent the sintered zirconia sintered body from being densified and from increasing the diameter of voids (pores) existing on the surface, the molding pressure is 1 × 10 ⁸ N / m ^2. It is desirable to set it above.

  The molded body thus obtained is degreased in the air, and is heated to 1300 ° C. or higher and 1500 ° C. by a gas introduction baking furnace under a gas pressure higher than atmospheric pressure, for example, by gas pressure baking, hot pressing, HIP or the like. By holding at the following maximum firing temperature for 1 hour or more and 3 hours or less, and further firing from this maximum firing temperature to 100 ° C. at a rate of temperature fall in the range of 120 ° C./h or more and 200 ° C./h or less. A high-strength zirconia sintered body can be obtained.

The reason why the firing is performed at a pressure larger than the atmospheric pressure as described above is that an additive such as SiO _{2 having a} melting point lower than that of ZrO ₂ due to the pressure in the firing furnace, and the stabilizer Y that could not completely dissolve in ZrO _{2. This is because 2} O ₃ is moved to the grain boundary of the zirconia sintered body during firing. When the firing pressure is higher than atmospheric pressure, the SiO ₂ component having a melting point lower than that of ZrO ₂ moves to the grain boundary of the lower pressure zirconia crystal. In this case, _Y 2 _{O 3} of a stabilizer which has not been dissolved in the ZrO _2, together with SiO ₂ component melts and moves to the ZrO ₂ grain boundaries. Thereby, the sintered zirconia sintered body has an amorphous phase containing a Y element and a Si element at the grain boundary. Here, the grain boundary is, for example, a boundary portion between adjacent zirconia crystals and includes a so-called triple point. The triple point means a grain boundary of a plurality of crystals 2 that are in contact with each other as shown in FIG. In FIG. 1, a triple point 1 is formed by four zirconia crystals 2, and an amorphous phase containing a Y element and a Si element is also formed at the triple point 1.

The zirconia sintered body added with 2 mol% of Y ₂ O ₃ manufactured by the above manufacturing method as a stabilizer is composed of Y element with respect to 100 mass% of the amorphous phase present at the grain boundary. A mass ratio becomes in the range of 0.1-10 mass%. Although the reason for this is not clear, by setting the temperature drop time from the maximum temperature to 100 ° C. in the range of 120 ° C./h or more and 200 ° C./h or less, SiO having a low melting point mainly at the grain boundaries. ₂ gather to form an amorphous phase. At this time, it is presumed that Y ₂ O ₃ that could not be completely dissolved in zirconia was taken into the amorphous phase within the range of the mass ratio. The reason why SiO ₂ does not crystallize and becomes an amorphous phase is that the temperature is lowered at 120 ° C./h or more and 200 ° C./h or less, which is faster than before, and the SiO ₂ is cooled before crystallization. This is because it forms a sintered body.

  Further, when the maximum firing temperature is lower than 1300 ° C., it is not sufficiently sintered, and when it is higher than 1500 ° C., the grain growth is remarkable, so that the crystal grain size is too large and the strength is lowered. Furthermore, in order to obtain a high-strength zirconia sintered body, the maximum firing temperature is preferably 1350 ° C. or higher and 1480 ° C. or lower. Furthermore, it is preferable to use, for example, an inert gas such as Ar or nitrogen, or an oxygen gas as a gas introduced in the firing step.

Furthermore, the zirconia sintered body is heat treated at a temperature of 750 to 850 ° C. in an inert gas atmosphere such as Ar or nitrogen, so that yttria (Y ₂ O ₃ ) or silica is formed at the grain boundary of the zirconia crystal. A crystal phase composed of a crystal such as (SiO ₂ ) is generated, and a zirconia sintered body having further improved mechanical strength can be obtained. The yttria (Y ₂ O ₃ ) or silica (SiO ₂ ) is generated by crystallizing a part of the amorphous phase by heat treatment. Examples of crystals that can be generated include Y ₂ O ₃ , SiO ₂ , Y ₂ Si ₂ O ₇ , and other cases where a crystal phase composed of a crystal of a compound containing Y, Si, O, and Zr elements is generated. There is also. These crystal phases are produced in a form dispersed in the boundary between the active amorphous phase and the zirconia crystal phase, or in a form dispersed in the amorphous phase. The generation of such a crystal phase prevents the development of cracks generated at the grain boundaries under stress loading, thereby improving the fracture toughness and making the ceramic phase made of a zirconia sintered body. The mechanical properties of the blade are improved.

In addition, the presence or absence of a crystal phase composed of a crystal such as yttria (Y ₂ O ₃ ) or silica (SiO ₂ ) can be confirmed by an electron beam diffraction method at the time of observation with a transmission electron microscope (TEM). Using a dispersive X-ray diffractometer, it is possible to calculate the mass ratio of each crystalline phase of yttria (Y ₂ O ₃ ) or silica (SiO ₂ ) from the number of Y or Si element counts in that portion. .

  Then, both surfaces of the zirconia sintered body thus obtained are ground by a surface grinder using a diamond grindstone as a tool. Furthermore, a ceramic blade having a desired blade can be obtained by performing a cutting process using a diamond wheel.

  Here, for the Y element mass ratio in the amorphous phase, the element count number of the amorphous phase portion present at the grain boundary of the zirconia sintered body is calculated using an energy dispersive X-ray diffractometer, From the calculated element count and the molecular weight of each element, the weight ratio of the grain boundary portion is calculated. And it is possible to obtain | require the mass ratio of Y element by implementing this method over ten places or more, and calculating those average values. It should be noted that the measurement location by the energy dispersive X-ray diffractometer can measure any portion as long as it is an amorphous phase portion of the grain boundary. By measuring, it is possible to obtain a more accurate measurement result. The measurement with an energy dispersive X-ray diffractometer was performed by confirming the measurement location with a transmission electron microscope at a high magnification, then setting the electron beam irradiation spot diameter to 0.5 to 5 nm, measuring time 30 to 75 sec, and measuring energy width 0. The measurement is performed under the condition of 1 to 50 keV. Further, a thin film approximation method is used as a quantitative calculation method.

(Measuring method of particle diameter of zirconia crystal particles)
In the present invention, the particle size of the ZrO ₂ crystal was measured by the planimetric method. First, a ZrO ₂ crystal structure is photographed at a magnification of 10,000 times with a SEM (scanning electron microscope) on the sintered surface of the sintered body obtained by firing, and a circle with a known area is obtained on the obtained photograph. Draw and count the number of particles in the circle and the number of particles on the circumference, and calculate the average crystal grain size as follows.

When A is the area of a circle, Nc is the number of particles in the circle, Ni is the number of particles applied to the circumference, and m is the magnification, the number of particles per unit area Ng is (Nc + (1/2) × Ni) / (A / m ² ), the particle number Ng per unit area is obtained by obtaining the area A of the circle, the number of particles Nc in the circle, the number of particles Ni applied to the circumference, and the magnification m. Obtainable. Further, since the area occupied by one particle is represented by 1 / Ng, the area occupied by one particle can be obtained by obtaining the number Ng of particles per unit area. Here, since 1 / √ (Ng) corresponds to the average crystal grain size, the average crystal grain size can be obtained by obtaining the number Ng of particles per unit area.

With respect to the ceramic blade of the present invention, an accelerated durability test for high chlorine concentration water was performed by changing the amount of SiO ₂ added to the zirconia sintered body and the mass ratio of Si and Y elements in the grain boundary.

  Hereinafter, the sample No. The detail of the manufacturing method of 1-10 is shown.

First, the Y ₂ O ₃ addition amount of the stabilizer is 2 mol%, and the commercially available ZrO ₂ primary material (average particle size 0.1 μm) produced by the coprecipitation method is added to the additive SiO ₂ , organic and adding a binder to prepare an average particle size of 50 [mu] m, the secondary material is a granulated powder of particle size range _{(D 10} ~D 90) _100μm with a spray dryer. At this time, the additive SiO ₂ was added as a SiO ₂ sol in the ratio shown in Table 1. Thereafter, the obtained secondary material is molded into a test piece shape in accordance with JIS R1601 after firing using a die press molding machine, and fired in an Ar gas pressure atmosphere of 1.5 atm. The sample was held in the furnace at a maximum temperature of 1450 ° C. for 2 hours, and the temperature was lowered at the rate of temperature drop as shown in Table 1, respectively. 1-10 were obtained. The number of samples prepared (n number) was 20, and after firing, grinding was performed using a surface grinder, and then the sample surface was further mirror-finished.

  The corrosion resistance of the samples of the zirconia sintered body thus obtained was evaluated. A three-point bending strength test according to JIS R1601 after immersing a sample in water at a temperature of 80 to 100 ° C. having a chlorine concentration (100 μg / g) 100 times the amount of chlorine contained in conventional water for 200 hours or more ( The mechanical strength was measured according to the number of n = 20) and evaluated for acceleration. As for the strength, it is judged that the strength of 20 or more with a strength variation of ± 60 MPa at 1000 MPa or more is good.

  Further, regarding the mass ratio of Y and Si in the amorphous phase at the grain boundary of the zirconia sintered body, the amorphous phase at the grain boundary was confirmed with a transmission electron microscope (manufactured by JEOL, acceleration voltage 200 kV). Thereafter, using an energy dispersive X-ray diffractometer (manufactured by Noran Instruments, spot diameter φ1 nm), the mass ratios of Y and Si elements are calculated from the element count of that portion.

The results are shown in Table 1. Sample No. In 11 to 13, samples prepared using primary raw materials in which the additive amount of Y ₂ O _{3 as} a stabilizer was 3 mol% were also prepared, and this evaluation was also performed. Further, stabilizers Y ₂ O ₃ amount of zirconia sintered body in Table (mol%), the additive amount of SiO ₂ (mass%) represents each composition ratio in the case of a 100% sintered body The Y element (mass%) in the amorphous phase and the Si element (mass%) in the amorphous phase, which are grain boundary compositions, represent the ratio of each element when the grain boundary is 100%. . Further, regarding the strength after the acceleration test, after immersing the sample in water having a high chlorine concentration at a temperature of 80 to 100 ° C. for 200 hours or more, the three-point bending strength was measured in accordance with JIS R1601, and (average value) ± (Standard deviation).

  From Table 1, Sample No. which is out of the scope of the present invention. For 1, the temperature drop rate was as fast as 300 ° C., and since the mass ratio of Y element in the amorphous phase at the grain boundary was small, the corrosion resistance was lowered, so although the absolute value of the mechanical strength was high, the strength variation was large, It does not have useful properties as a blade member.

Sample No. For Samples 6 and 7, Sample No. Contrary to 1, the temperature-decreasing rate was too high, so the mass ratio of the Y element in the amorphous phase at the grain boundary was high, and the amount of the solid solution of the stabilizer Y ₂ O _{3 in} ZrO ₂ was small. Therefore, the phase transformation of the zirconia sintered body was increased, and the mechanical strength was lowered.

Sample No. For No. 12, the rate of temperature decrease was high, and the amount of Y ₂ O ₃ added as a stabilizer was large, so that the mass ratio of Y element in the amorphous phase at the grain boundary was too high. Sample No. Regarding No. 13, since the temperature drop rate was low and the amount of Y ₂ O ₃ added as a stabilizer was large, the mass ratio of Y element in the amorphous phase at the grain boundary was too low. As a result, no. No. 12 has low corrosion resistance and lower strength. No. 13 had a small amount of Y solid solution in ZrO ₂ and a large phase transformation, so that the mechanical strength was lowered.

In addition, the specimen No. No. 8 has a small amount of added SiO _{2 and a} small mass ratio of Si element in the amorphous phase of the grain boundary. For Nos. 9 and 10, the amount of SiO ₂ added was large, and therefore the mass ratio of Si element in the amorphous phase of the grain boundary increased, so that the mechanical strength tended to be low.

Compared with these, sample No. within the scope of the present invention. 2 to 5 and the stabilizer Y ₂ O ₃ addition amount is large and the mechanical strength is slightly inferior. 11 also showed good evaluation results.

Next, sample No. 1 within the scope of the present invention in Example 1 was used. 4 and 5, heat treatment was performed at 800 ° C. in a nitrogen atmosphere. 14 and 15 were produced. The ratio of the respective crystal phases composed of yttria (Y ₂ O ₃ ) or silica (SiO ₂ ) crystals is first confirmed by electron beam diffraction under transmission electron microscope observation, and further the energy dispersive X Using a line diffractometer, the mass proportion of each crystalline phase of yttria (Y ₂ O ₃ ) or silica (SiO ₂ ) was calculated from the element count of that portion. Moreover, the acceleration test was done like Example 1 and the mechanical strength of each sample was measured.

From Table 2, sample No. without heat treatment. For Samples 4 and 5, Sample Nos. Obtained by heat treatment were used. In Nos. 14 and 15, the amount of yttria (Y ₂ O ₃ ) or silica (SiO ₂ ) crystal phase increased, and the mechanical strength increased.

Next, sample No. 1 within the scope of the present invention in Example 1 was used. Sample No. 4 composed of a zirconia sintered body having an average crystal grain size adjusted as shown in Table 2 by adjusting the grain size of the primary raw material used using the same production specifications as in Table 4. 16-22 were produced. And the bulk density and the relative density were measured. Moreover, the test which confirms about the mechanical strength after implementing a corrosion resistance test on the conditions similar to Example 1 was implemented. The results are shown in Table 3.

Sample No. For No. 16, since the ZrO ₂ powder in which Y ₂ O ₃ used was dissolved was too small at 0.04 μm, the average crystal grain size of the zirconia sintered body was too small at 0.2 μm, and added Y ₂ Dispersibility of the O ₃ stabilizer was poor, and as a result, the mechanical strength of the sintered body was lowered and the variation thereof was large.

Sample No. For samples 19 and 20, sample no. 16 is because the grain size of the ZrO ₂ powder in which Y ₂ O ₃ used as a target is solid solution is 0.3 μm or more, the sinterability is poor and the average crystal grain size of the sintered body is 0.7 μm, Despite grain growth of 0.9 μm, the density was low and the mechanical strength decreased.

Next, sample no. No. 4 made of a zirconia sintered body constituting the ceramic blade of the present invention by adjusting the particle size distribution of the ZrO ₂ granulated powder used in the same production specifications as in No. 4. After preparing 23-28, the test which evaluates mechanical strength on the conditions similar to Example 1 was implemented. The results are shown in Table 4.

Sample No. As for No. 23, since the D ₅₀ value of the powder used was as small as 30 μm, the moldability during molding was poor, and D ₉₀ was also outside the preferred range of 10 to 100, and the strength decreased. Also, the variation became larger. Sample No. The 26 is _a satisfactory range for _{D 50,} although moldability was _good, the strength variation is increased to _{D 90} of it was suitable range and 30 to 150 [mu] m. Furthermore, sample no. As for No. 28, although D ₉₀ was in the preferred range, D ₅₀ was out of the preferred range of 60 μm, so that the granulated powder was not crushed and the formability was poor, so the strength was lowered.

Compared with these, sample no. Regarding 24, 25, and 27, D ₅₀ and D ₉₀ were both within the preferable range, and good characteristics were exhibited.

Next, the relationship between the ZrO ₂ content in the zirconia sintered body and the three-point bending strength is shown. Samples with ZrO ₂ content of 94, 95, 98 or 99 mass% were prepared. 29-32. Sample No. In any of samples 29 to 32, the content of the additive SiO ₂ contained in the zirconia sintered body was set to 0.4% by mass. Table 5 shows the mechanical strength based on the ZrO ₂ content and the three-point bending strength.

Sample No. with a ZrO ₂ content of 94% by mass. In the case of 29, the three-point bending strength was 980 MPa. On the other hand, sample Nos. With ZrO ₂ content of 95 mass%, 98 mass%, and 99 mass%. 30 to 32, the three-point bending strengths are 1103, 1170, and 1230 MPa. It was found to be much higher than 29. It was also found that the mechanical strength was improved as the ZrO ₂ content was increased. This is because the impurity content increases as the ZrO ₂ content contained in the zirconia sintered body decreases, and the mechanical strength and corrosion resistance decrease. The ZrO ₂ content in the zirconia sintered body is more preferably 95% by mass or more, and still more preferably 98% by mass or more. Here, the ZrO ₂ content of 95% by mass means that 95% by mass of ZrO ₂ previously stabilized with Y ₂ O _{3 is} contained.

It is a schematic diagram of the TEM photograph which showed the zirconia crystal grain boundary (triple point).

Explanation of symbols

1: Triple point 2: Crystal

Claims (10)

A crystal phase composed of crystals of zirconia (ZrO ₂ ) as a main component, a crystal phase composed of crystals of yttria (Y ₂ O ₃ ) or silica (SiO ₂ ), and an amorphous phase containing a Y element and a Si element. A ceramic blade having a zirconia sintered body having a mass ratio of Y element to 100 mass% of the amorphous phase of 0.1 mass% or more and 10 mass% or less. 2. The ceramic blade according to claim 1, wherein a mass ratio of the Si element with respect to 100 mass% of the amorphous phase is 0.1 mass% or more and 10 mass% or less. The ceramic knives according to claim 1 or 2 , wherein the zirconia sintered body contains 95 mass% or more of zirconia. The zirconia sintered body, Si and SiO ₂ in terms of 0.05% by mass or more, and a ceramic edged tool according to any one of claims 1 to 3, characterized in that it contains 0.40% by mass or less. The ceramic blade according to any one of claims 1 to 4 , wherein the mass ratio of the Y element and the Si element is calculated from an element count by energy dispersive X-ray spectroscopy. The crystalline zirconia in the zirconia sintered body has an average grain size of 0.3μm or more and ceramic edged tool according to any one of claims 1 to 5, characterized in that at 0.5μm or less. The bulk density of the zirconia sintered body, 6.03 g / cm ³ or more, a ceramic edged tool according to any one of claims 1 to 6 relative density is equal to or less than 99%. A method for producing a ceramic blade according to any one of claims 1 to 7,
Mixing a ZrO ₂ powder stabilized with Y ₂ O ₃ and a SiO ₂ sol, obtaining a granulated powder, and obtaining a molded body obtained by shaping the granulated powder into a blade shape; The molded body is heated at a maximum firing temperature of 1300 ° C. or higher and 1500 ° C. or lower at a gas pressure greater than atmospheric pressure in a baking furnace, and the temperature lowering rate from the maximum temperature to 100 ° C. is 120 ° C. or higher and 200 ° C. The manufacturing method of the ceramic blade characterized by having the process of obtaining the sintered compact baked at / h or less, and the process of grinding to the said sintered compact. The method for producing a ceramic blade according to claim 8 , wherein the ZrO ₂ powder stabilized by Y ₂ O ₃ has a particle size of 0.05 µm or more and 0.2 µm or less. The granulation average particle size of the powder _{(D 50)} is 40μm or more and 55μm or less and a particle size range _(D 10 _{~D 90)} is, according to claim, characterized in that 20μm or more, and 130μm or less 8 Or the manufacturing method of the ceramic blade as described in 9 .

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