KR20110100614A - Zirconia single crystal growing method - Google Patents

Abstract

The present invention relates to a zirconium oxide single crystal having excellent mechanical workability and a method for manufacturing the same, comprising ZrO 2: 96 to 92 wt%, Y 2 O 3: 4 to 8 wt%, and other unavoidable pures, grown by a scull method, and It provides a zirconium oxide single crystal with (cubic), monoclinic (Monoclinic) and tetragonal crystal phases together.

Description

Manufacturing method of zirconium oxide single crystal {ZIRCONIA SINGLE CRYSTAL GROWING METHOD}

TECHNICAL FIELD The present invention relates to a zirconium oxide single crystal having excellent mechanical workability and a method for producing the same. More specifically, the present invention relates to a method for preparing a zirconium oxide single crystal having high mechanical strength and high fracture toughness and excellent thermal stability, and to utilizing zirconium oxide produced by the manufacturing method as an industrial component material and a medical material. .

Zirconium oxide (ZrO2) has high strength characteristics and is used as a die for die extrusion using ceramic scissors, medical materials, or lubricity. In addition, zirconium oxide has excellent thermal properties and is used as a component for heat-insulated engines, and has good electrical conductivity against oxygen ions, and has been applied to components of oxygen sensors and fuel cells.

The zirconium oxide itself has a very high melting point of 2,750 ° C and the crystal phase structure changes with temperature change. Such zirconium oxide has a crystal structure of cubic crystal at high temperature, but when cooled to room temperature, phase transition occurs to monoclinic or tetragonal, at which time a volume change occurs and defects are generated.

As described above, zirconium oxide has excellent physical properties but has a high melting point, so that zirconium oxide is usually synthesized and used as a sintered body.

Even when the zirconium oxide is synthesized as a sintered body, due to the volume change due to the phase transition of the zirconium oxide, rare earth metal oxides are usually added to the zirconium oxide to synthesize the equiaxed crystal phase, which is a stable crystal phase at high temperature, at room temperature.

However, the zirconium oxide sintered body to which the stabilizer is added also has a problem of causing cracks in the sintered body due to the volume change generated at this time, while the tetragonal tetragonal phase, which is metastable at room temperature, transitions to a monoclinic system by aging.

In addition, the sintered body of zirconium oxide known to date is relatively excellent in strength characteristics, but due to the internal pores, the toughness is inferior, there is a problem that can not be processed into parts in the desired shape.

When zirconium oxide is prepared as a single crystal, there are several advantages in physical properties. However, such zirconium oxide has a very high melting point and cannot be grown into a single crystal using a crucible. Even if zirconium oxide is grown as a single crystal, rare-earth metal oxides are usually added because the equiaxed crystal system is not obtained at high temperature. However, the single crystal grown in this way has a disadvantage in that it is easy to break because the crystal phase is equiaxed. In addition, the zirconium oxide single crystal is colored due to the added rare earth metal oxide.

Therefore, colored zirconium oxide single crystals to which rare earth-based metal oxides are known so far cannot be processed into precise parts because they have high strength and low toughness. Therefore, unlike sintered bodies, they are used as medical materials, engine parts or cutting tools. There is a problem that can not be used.

An object of the present invention is to provide a method for producing a zirconium oxide single crystal having high hardness and high strength but also high fracture toughness and excellent mechanical workability.

According to an embodiment of the present invention for achieving the above object is made of ZrO2: 96 ~ 92 wt% and Y2O3: 4 ~ 8 wt% and other unavoidable impurities, is grown by the scull method, the cubic and It provides a zirconium oxide single crystal in which tetragonal crystal phases exist together and optionally some monoclinic (Monoclinic) crystal phases exist in an equiaxed crystal system.

According to another embodiment of the present invention for achieving the above object is mechanically processed using the grown zirconium oxide single crystal to provide a medical material and industrial material.

Medical materials include dental materials and orthopedic materials, and dental materials may be any one of abutments, implant drills, prostheses, implants, abutment screws, and artificial teeth. And orthopedic materials may be used as any one of artificial bones, surgical bolts, surgical nuts, drills.

And as an industrial material can be used any one of an end mill, industrial knife, scissors, comb.

According to an embodiment of the present invention for achieving the above object, i) a step of charging raw materials of ZrO 2: 96-92 wt% and Y 2 O 3: 4-8 wt% in a skull crucible for growing a single crystal by high frequency induction heating; ; Ii) placing zirconium oxide metal particles or agglomerates of carbon in the skull crucible; Iii) applying power to a high frequency induction apparatus to melt the charged material starting from the zirconium oxide metal particles or carbon agglomerates inside the scull crucible; Iii) supplementing and supplying the raw material to the top of the scull crucible while raising the induction coil outside the scull crucible at a speed of 1 to 20 mm / hr; Iii) shutting off the power of the high frequency induction apparatus when the growth of the zirconium oxide single crystal is completed in the scull crucible; And iii) cooling the grown zirconium oxide single crystal at a cooling rate of 110 to 70 ° C / hr while maintaining the inside of the scull crucible; It provides a method for growing a zirconium oxide single crystal comprising a.

Single crystals grown in accordance with one embodiment of the present invention have fracture toughness of 1290 to 1603 (kgf / mm3 / 2) and bending strength of 329 to 352 (MPa).

Since the zirconium oxide single crystal according to the present invention has high bending strength and fracture toughness, not only can it be mechanically processed, but also ultrasonic processing and sand blast processing can be performed. Therefore, the grown single crystal can be used for various purposes such as a surgical knife, a drill used for precise and ultra-high speed machining, and a spacecraft component with excellent heat resistance.

In addition, when used as a dental material using the zirconium oxide single crystals grown in accordance with an embodiment of the present invention, the grown single crystals do not rust and do not cause inflammation, and the heat of friction is relatively higher than that of a drill made of a conventional material. Very small to prevent necrosis of the alveolar bone and gums, very good biocompatibility.

In addition, the grown single crystal has an ivory color that is almost the same as that of artificial teeth, and thus has excellent aesthetics, and because of its high mechanical strength, it can be used for a long time.

In addition, when the grown single crystal is used as a medical or dental material, since zirconium oxide single crystal is a ceramic material, there is an advantage of being biocompatible.

1 is a photograph showing the appearance of a single crystal grown in accordance with Example 2 which is an embodiment of the present invention.
Figure 2 is a micrograph showing the surface of the sintered body prepared according to Comparative Example 4 which is an embodiment of the present invention.
3 is a photograph of the surface of the single crystal grown according to Example 2, which is an embodiment of the present invention, using an electron microscope (SEM).
4 is a photograph showing a Laue X-ray diffraction pattern of a single crystal grown according to Example 2, which is an embodiment of the present invention.
5 is a crystal structure diagram illustrating a crystal lattice model of a single crystal grown according to Example 2, which is an example of the present invention.
Figure 6 shows a transmission electron micrograph of a single crystal grown in accordance with Example 2, an embodiment of the present invention.
FIG. 7 is an enlarged transmission electron micrograph of a crystal diffraction pattern of the matrix of FIG. 6.
8 is a transmission electron microscope photograph of the crystal diffraction pattern of FIG. 7 under different conditions.
FIG. 9 is an enlarged transmission electron micrograph of a crystal diffraction pattern for the precipitate of FIG. 6.
FIG. 10 is a transmission electron micrograph of the grain boundaries of the matrix and rod structure in FIG. 6.
FIG. 11 is a photograph showing a dental abutment processed using a single crystal grown according to Example 2, which is an embodiment of the present invention. FIG.
12 is a photograph showing an implant drill processed using a zirconium oxide single crystal grown according to Example 2, which is an embodiment of the present invention.
FIG. 13 is a photograph showing an industrial end mill processed using zirconium oxide single crystals grown according to Example 2, which is an embodiment of the present invention. FIG.

Hereinafter, embodiments of a zirconium oxide single crystal and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited to the following embodiments. Therefore, those skilled in the art may implement the present invention in various other forms without departing from the technical spirit of the present invention.

Hereinafter, the manufacturing method of the zirconium oxide single crystal of this invention is demonstrated in detail.

Zirconium oxide single crystal according to an embodiment of the present invention is grown by the skull method.

The skull device used for single crystal growth used a device similar to the device shown in Korean Patent Laid-Open No. 2001-0064655, which is the inventor's patent application.

The starting material used for the growth of zirconium oxide single crystal is 96-92 wt% of ZrO ₂ powder as the main raw material, 4-8 wt% of Y ₂ O ₃ powder is added as an additive, and other unavoidable impurities are included.

In an embodiment of the present invention, when the main raw material and the additive are added and grown as a single crystal, an equiaxed structure (cubic) structure, which is stable at high temperature, is maintained at room temperature. In addition, the grown single crystal is stable at room temperature, the crystal structure of the equiaxed system forms a matrix, and the rod-shaped tetragonal structure is uniformly dispersed in the matrix structure of the equiaxed system. In addition, some monoclinic (Monoclinic) structure may be distributed together in an equiaxed structure. That is, the zirconium oxide single crystal according to an embodiment of the present invention maintains a state in which cobic and tetragonal structures coexist at room temperature, and some monoclinic structures may be dispersed in the equiaxed crystal structure. have.

As such, when a monoclinic structure is selectively mixed with an equiaxed crystal structure in a state where the equiaxed crystal structure is the basic structure and the tetragonal structure is precipitated with directionality, the grown single crystal has high bending strength and high fracture toughness. Will be maintained. Single crystals grown to have such a crystal structure can enable precise mechanical processing. If the grown single crystal is composed of one crystalline phase that is equiaxed or tetragonal rather than a mixed phase, the bending strength is high but the fracture toughness is low, so brittleness is difficult and mechanical processing is difficult.

In addition, the single crystal grown in the composition of one embodiment of the present invention is not completely transparent, is translucent, and has an ivory color close to milky light. Therefore, single crystals with these colors can be used as artificial teeth. If another oxide is added to the grown single crystal, red, pink, blue, black or green may be used depending on the type of the added oxide and thus cannot be used as an artificial tooth. In addition, if the single crystal to be grown out of the composition specified in the present invention, even if the single crystal is grown, it can exhibit a transparent color and low bending strength, so that mechanical processing is impossible. Therefore, single crystals grown under these conditions cannot be used as artificial teeth.

Next, the high purity raw material prepared with the composition as described above is continuously charged into the skull crucible through the raw material charging device.

When charging raw materials into the scull crucible, a small amount of molten core material such as zirconium oxide metal particles or agglomerates of carbon is placed inside the charged raw materials. This is because zirconium oxide, the main raw material, has high electrical resistance in a powder state, and thus high frequency induction heating is not performed well. Therefore, a small amount of molten nucleus material is placed in the charged raw material, and the temperature is raised by the molten nucleus material to melt the whole raw material while heating and melting the whole raw material.

It is preferable that the high frequency for melting the raw material inside the scull crucible controls the oscillation frequency within the range of 10 KHz to 10 MHz.

The raw material in the skull crucible is melted by forming a high frequency electromagnetic field by a ring-shaped induction coil located outside the scull crucible.

The high frequency induction coil is connected to the high frequency generator and is controlled by a driving device which supports and guides the coil and moves it up and down.

In the initial stage of melting, the high frequency induction coil is located at the lower part of the scull crucible and the melt level is increased as the raw material is heated and melted around the molten core and the induction coil is gradually raised. At the same time, the raw material is continuously supplied to the skull crucible from the raw material charging device disposed above the skull crucible.

When the induction coil rises, the charged raw material gradually melts. When the charged raw materials are gradually melted, the raw materials in contact with the cooling water circulation coil of the scull crucible are not melted by the influence of the circulating coolant, but only the raw materials inside the scull crucible are melted.

The portion which is charged in the skull crucible and is not melted under the influence of the cooling water is sintered under the influence of the hot melt of the molten portion to form a sintered layer with a thickness of several mm. Therefore, this sintered layer serves as a single sintered layer crucible holding the melt. Therefore, the melt inside the sintered layer is blocked from the outside by the sintered layer crucible, thereby preventing the possibility of impurities penetrating from or contaminating therefrom.

The rate of rise of the induction coil ascending during melting of the filled raw material is controlled by the size and material of the scull crucible and the composition of the charged raw material. In one embodiment of the present invention, the rising speed of the induction coil is preferably controlled to 1 ~ 20mm / hr.

When the induction coil is raised at such a rate, the molten melted inside the scull crucible starts to grow from the seed because the sintered layer formed at the bottom of the scull crucible acts as a seed.

As the induction coil rises outside the scull crucible, single crystals continue to grow in the lower part of the scull crucible, and raw materials continuously supplied to the upper part of the scull crucible are sequentially melted. In this state, when the induction coil reaches the top region of the scull crucible, the high frequency generator is stopped.

In one embodiment of the present invention, the crystal phase of the single crystal grown from the lower portion of the scull crucible is determined according to the rising speed of the induction coil. If the induction coil has a high rising speed, it is not a single crystal but becomes a polycrystal. Therefore, it is preferable to maintain the rising speed of the induction coil at 1 to 20 mm / Hr to perform slow cooling.

The single crystal grown inside the scull crucible is isolated from the surroundings by the sintered crucible of the scull crucible and is cooled slowly while maintaining warmth.

At this time, the cooling rate of the grown single crystal is maintained at 110 ~ 70 ℃ / hr. Due to such slow cooling, the rod-shaped tetragonal structure is uniformly dispersed in the cubic matrix structure to maintain the precipitated state with orientation. And by this cooling rate, some monoclinic (Monoclinic) structure is dispersed together in the equiaxed structure of the matrix structure.

In this case, when the cooling rate of the grown single crystal is 110 ° C./hr or more, most of the crystal phases of the equiaxed crystal system are formed, so that the grown single crystal cannot be mechanically processed.

Single crystals grown according to one embodiment of the present invention have fracture toughness of 1290 to 1603 (kgf / mm ^3/2 ), and have a bending strength of 329 to 352 (MPa). Zirconium oxide single crystals having such physical properties are easy to be mechanically processed, and if they have physical properties outside these ranges, they are brittle and not easily mechanically processed.

The single crystals grown in accordance with one embodiment of the present invention were subjected to X-ray diffraction analysis to examine the crystal phase, and the bending strength, fracture toughness and Vickers hardness were measured to examine the physical properties.

In addition, the single crystal grown in accordance with one embodiment of the present invention was processed into a medical material, and also with a cutting tool.

Experimental Example

In order to cultivate zirconium oxide single crystals, the raw materials were blended with the composition shown in Table 1 below. The ZrO ₂ powder and the Y ₂ O ₃ powder used at this time are high purity products of 99.99% or more.

In Examples 1 to 3 and Comparative Examples 1 to 3, single crystals were grown in the following order using the skull single crystal growing method. First, raw materials of the composition shown in Table 1 below were filled in a skull crucible. When filling the raw material, carbon rings having good electrical conductivity (ten ten 5 mm thick plate-shaped carbon rings) were stacked and placed in the center portion of the inside of the raw material. The high frequency induction furnace was then operated to melt the raw materials. As the high frequency induction furnace was operated, the carbon ring acted as a molten nucleus to melt the raw material inside the skull crucible. At this time, the raw material powder in contact with the inner wall of the skull crucible was operated to cool the skull crucible itself so that the raw material powder does not melt and maintain the sintered layer state. Therefore, only the raw material in the sintered layer state that is not melted is continuously melted. Then, the high frequency induction coil was raised at a rate of 10 mm / Hr, while the raw materials having the compositions of the respective examples and the comparative examples were continuously supplied from the raw material charging device disposed above the crucible. When the induction coil reached the top region of the skull crucible, the high frequency generator was turned off and cooled until it reached room temperature. At this time, the induction coil rising speed and the cooling conditions of the skull crucible of Examples 1 to 3 and Comparative Examples 1 to 3 were applied in the same manner.

On the other hand, the sintered compact of Comparative Example 4 was mixed with the raw materials shown in Table 1 having an average particle diameter of 0.5㎛ and then molded into a disk form and sintered at 1600 ℃.

The crystals grown according to the conditions of Examples 1 to 3 and Comparative Examples 1 to 3 were completely cooled to room temperature, and then the skull crucible was decomposed to observe the appearance of the crystals grown inside the crucible. As a result, in the case of Comparative Example 1, it was not able to maintain a single crystal state, but maintained a shattered polycrystal form like a sintered body. From these results, it can be seen that the composition of Comparative Example 1 is difficult to grow single crystals.

However, in Example 2, as shown in Fig. 1, a plurality of single crystals were grown in a columnar shape, and the color was ivory. Also in Example 1 and Example 3, the grown single crystal showed a form similar to that of Figure 1.

On the other hand, in the case of Comparative Example 2 and Comparative Example 3, the appearance of the grown single crystal was similar to Example 1, but was grown in a colorless and transparent state.

In the case of the sintered compact of Comparative Example 4, the photograph of the surface of the specimen in the sintered state was observed by using an electron microscope (SEM).

The sintered body produced according to Comparative Example 4 has a grain boundary (Grain Boundary), as shown in Figure 2, each grain was an average diameter of 0.4 ㎛.

The physical properties of the monocrystals grown according to the following examples and the polycrystals, single crystals, and sintered bodies grown according to the comparative examples were investigated.

Physical properties were measured for Vickers hardness, fracture toughness, bending strength and specific gravity. The Vickers hardness was measured using the model name VMT-7 manufactured by MATSUZAWA of Japan according to the measurement method of Korean Industrial Standard KS L 1603 [2006]. At this time, the loading speed was 50 s / sec and the loading time was 10 sec.

Fracture toughness was measured according to the Korean Industrial Standard KS L 1603 [2006] using the model name VMT-7 manufactured by MATSUZAWA of Japan. At this time, the loading speed was 50 s / sec and the loading time was 10 sec.

 The bending strength was measured according to the Korean Industrial Standard KS L 1591 [2006] using Instron's universal testing machine (Model No. 4204). At this time, the measurement speed was 0.5 mm / min.

The measurement results of the test pieces thus measured are shown in Table 1 below.

division ZrO ₂
(wt%) Y ₂ O ₃ (wt%) Vickers Hardness
(HV20) Fracture toughness
(kgf ^/ mm ^3/2) Bending strength
(MPa) importance Remarks Comparative Example 1 99.0 1.0 1203 1057 155 6.18 Polycrystalline Example 1 96.0 4.0 1217 1487 342 6.12 Single crystal Example 2 95.0 5.0 1230 1603 352 6.10 Single crystal Example 3 92.0 8.0 1322 1290 329 6.04 Single crystal Comparative Example 2 88.0 12.0 1458 873 298 5.97 Single crystal Comparative Example 3 82.0 18.0 1512 247 251 5.85 Single crystal Comparative Example 4 95.0 5.0 1343 1207 173 6.06 Sintered body

As shown in Table 1, in Examples 1 to 3, while showing a high Vickers hardness value, the fracture toughness and the bending strength also showed a high measured value. On the contrary, even in the case of the same single crystal, the Vickers hardness values were high in Comparative Examples 2 to 3, but the fracture toughness and bending strength were significantly lower. The reason for this is that the crystal phase shows a complex phase in the case of the examples, but it is presumed that the crystals are grown in a tetragonal single phase in the comparative examples. In addition, in the case of Comparative Example 4, which is a sintered body, the Vickers hardness value was high, but the fracture toughness and the bending strength were low. In the case of Comparative Example 1 grown with polycrystal, Vickers hardness value was also low, and both fracture toughness and bending strength were lower than those of Example.

In order to confirm the crystal structure of the single crystal grown in accordance with the embodiment, the single crystal grown in accordance with the conditions of Example 2 was observed with an electron microscope (SEM). To this end, the single crystal of Example 2 was thermally etched at 1400 ° C. for 1 hour. 3 shows the results of observing the crystal structure of the thermally corroded test piece with an electron microscope (SEM).

As can be seen in Figure 3, the single crystal grown in accordance with the embodiment has a predetermined orientation of the rod-shaped precipitate (Precipitation) of the average diameter of 0.05 ~ 0.2㎛ and 0.5 ~ 1.5㎛ size on the matrix (matrix) It is visible and uniformly distributed.

In order to confirm the crystal structure of the grown crystals, Laue X-ray diffraction analysis (Laue X-ray Diffraction Patten) experiment was performed and the results are shown in FIG. For the Lauer X-ray diffraction analysis experiments, the crystals of Example 2 were prepared by cutting and polishing 0.5 mm × 0.6 mm × 1 mm. The analyzer used at this time was SMART APEX II. The target was Mo and the average value of the Ka1 / Ka2 line was 0.71053 파장, and the analysis was performed under the conditions of voltage 50kW and current 30mA at 297K.

As a result of analyzing the Lauer diffraction pattern of FIG. 4, it was confirmed that the crystal grown according to Example 2 was a zirconium oxide (ZrO 2) single crystal of cubic, and the lattice parameter of the crystal was about 5.1 μs. . The crystal lattice having such a condition is shown in FIG. In FIG. 5, the red atom located at the center means oxygen, and the white atom located at the corner and each crystal plane means zirconia.

In order to analyze the microstructure of the single crystal (Matrix) and the precipitate (Precipitation) shown in Figure 3 was observed the crystal structure using a transmission electron microscope (TEM). The transmission electron microscope used was JEOL JEM-4010 model, and the acceleration voltage at the time of measurement was 400 kV. 6 shows a transmission electron micrograph of a single crystal grown in accordance with Example 2 as described above.

As shown in FIG. 6, as a result of analyzing the electron diffraction pattern in the matrix region of the crystal, the crystal structure was interpreted as cubic, which is consistent with the analysis result by the Lauer diffraction pattern. .

In FIG. 6, the portions indicated by three rectangles in the upper left picture represent regions in which rod-shaped precipitates are shown in FIG. 3. As a result of analyzing the Selective Area Diffraction Pattern (SADP) on this rectangular portion, the crystal structure of this portion was interpreted as a tetragonal crystal structure different from the matrix. When the image of the dark-field TEM was photographed by the diffraction point confirmed by the SADP, only a portion of tetragonal crystal structure was brightly seen as shown in the lower left picture of FIG. 6.

In FIG. 6, three rods are continuously observed in the upper and lower detailed transmission electron micrographs of the left and right because the precipitates present in the upper and lower portions or the center of the crystal were observed as the electrons transmitted through the specimen. to be.

In order to analyze the crystal phase of the single crystal grown by Example 2 in more detail, the matrix structure and rod-shaped precipitates observed in FIG. 6 were observed by SADP, and the results are shown in FIGS. 7 to 9.

FIG. 7 is an enlarged view of the SADP for the matrix (Matrix) observed in FIG. As a result of analyzing each diffraction point as shown in FIG. 7, the angle of each diffraction vector was 90 ° and the magnitude of the inverse lattice vector was the same in the a-axis and the b-axis. As can be seen from these results, it was confirmed that the matrix structure of the grown single crystal was composed of the crystal structure of the cubic system and the crystal structure of the equiaxed system was formed entirely on the grown single crystal.

8 shows better the minor peaks observed in the SADP of the matrix region shown in FIG. As a result of analyzing the diffraction pattern of FIG. 8, it was confirmed that the minor peaks had an angle β of the diffraction vector of about 81 ° and the magnitude between the inverse lattice vectors of about 0.965 in the a-axis and the c-axis. These results are the same in comparison with the angle between the crystal axes (β = 81.22) and the lattice constant (a = 5.1881, b = 5.2142, c = 5.3835) of the monoclinic (Monoclinic) crystal structure of zirconium oxide single crystal. Can be. From these results, it was confirmed that the minor peak in the matrix region had a monoclinic crystal structure. Therefore, this analysis shows that although there is a small amount, some mixed monoclinic (Monoclinic) crystal structure exists in the matrix structure.

9 is an enlarged view of the SADP of the precipitates observed in FIG. 6. As a result of analyzing each diffraction point as shown in FIG. 9, the angle of each diffraction vector was 90 ° and the magnitude of the inverse lattice vector was 0.97. This result is the same as compared with the angle (90 °) of the crystal vector of the tetragonal crystal structure of the zirconium oxide single crystal and the lattice constant (a = 5.1485, c = 5.2692) of each crystal axis. As can be seen from these results, it was once again confirmed that the grown single crystal rod-shaped precipitates consisted of tetragonal crystal structures. The photograph shown in the small box at the upper right of FIG. 9 shows that the tetragonal crystals grew in the c-axis direction, which is the long axis.

On the other hand, Figure 10 is a photograph analyzed by high-resolution transmission electron microscope (High-Resolution TEM) of the interface between the matrix and the rod-like precipitate for the single crystal grown in Example 2. As shown in FIG. 10, the crystal lattice was well observed in the rod-shaped tetragonal crystal structure, but the crystal lattice was not observed well in the cubic crystal structure forming the matrix structure. This is due to the fact that some of the monoclinic (Monoclinic) crystal structures are mixed with the cubic crystal structure in the matrix structure. It is assumed that this occurred. In addition, it is assumed that the contrast occurs in the grain boundary region between the matrix structure and the precipitate because the stress between the cubic crystal structure and the tetragonal crystal structure is concentrated at the grain boundary. .

As described above, as shown in FIGS. 6 to 9, the single crystals grown in Example 2 as a result of transmission electron microscope (TEM) analysis have a matrix structure composed of cubic, and a rod shape deposited on the matrix structure. Precipitation of is a tetragonal crystal structure, and it can be confirmed that these precipitates are oriented with the orientation on the matrix structure. In addition, it can be seen that some monoclinic (Monoclinic) crystal structure is mixed in the matrix structure.

As described above, the zirconium oxide single crystals grown in accordance with one embodiment of the present invention were processed with an abutment, an implant drill, and an industrial end mill, respectively, in order to check whether the zirconium oxide single crystal could be used as a medical material. As a result, when machining with abutments, implant drills and industrial end mills with a zirconium oxide single crystal as in one embodiment of the present invention, precise machining was possible as shown in FIGS. However, the single crystals according to Comparative Examples 2 and 3 and the sintered bodies according to Comparative Example 4 were used as dental abutments, implant drills, and industrial end mills, respectively, but were easily crushed and mechanically processed. In particular, the sintered compact according to Comparative Example 4 was formed in a tetragonal crystal structure. As described above, zirconium oxide having a tetragonal crystal phase showed degradation in H ₂ O atmosphere at 100 to 200 ° C., and thus easily collapsed. This deterioration is because the tetragonal crystal structure in the H ₂ O atmosphere of 100 to 200 ℃ causes a phase change to a monoclinic (Monoclinic) crystal structure.

FIG. 11 is a photograph of a zone column processed with a zirconium oxide single crystal grown according to Example 2, which is an embodiment of the present invention, and FIG. 12 is a photograph of an implant drill processed with a zirconium oxide single crystal grown according to Example 2, Fig. 13 is a photograph of an industrial end mill processed from zirconium oxide single crystals grown in accordance with Example 2;

In Figure 11, the abutment at the top is a titanium abutment for comparison with an embodiment of the present invention, and the abutment at the bottom is manufactured by machining a zirconium oxide single crystal grown in accordance with an embodiment of the present invention. It is rent. As shown in FIG. 11, the abutment prepared by processing the zirconium oxide single crystals grown according to the embodiment of the present invention has a precisely machined screw portion. This fact means that the grown zirconium oxide can be precisely processed without being destroyed even if it is precisely machined.

12 shows that the drill for the implant at the upper left is made of conventional trimlite stainless steel, and the drill for the implant at the upper right, lower left and lower right is oxidized according to Example 2 It shows the thing processed using the zirconium single crystal.

The three implant drills processed using the zirconium oxide single crystals grown according to the embodiment of the present invention as shown in FIG. 12 were processed differently in diameter and length. This indicates that precision processing is possible even when processing in various forms. As such, drills for implants of different diameters and lengths are used to drill small holes in the alveolar bone and gradually widen the holes, and are generally used for primary, secondary or tertiary drilling depending on their diameter. .

13 shows an industrial end mill made of tungsten cemented carbide, and an intermediate photograph shows an industrial end mill processed using zirconium oxide single crystals grown according to Example 2 of the present invention. It shows that titanium was coated on the surface of an industrial end mill processed using a zirconium oxide single crystal grown in accordance with Example 2 of the present invention.

As described above, as a result of processing the abutments, implant drills, and industrial end mills using the zirconium oxide single crystals grown according to one embodiment of the present invention, precision processing was possible as shown in FIGS. 11 to 13, but Comparative Example 2 The single crystals of 3 to 3 and the sintered body of Comparative Example 4 exhibited brittleness and were all broken when processed into such dental materials.

Therefore, the zirconium oxide single crystals grown in accordance with one embodiment of the present invention can be used as a dental material and industrial processing material, since the precision processing is possible.

Parts that can be used as dental materials using zirconium oxide single crystals grown in accordance with one embodiment of the present invention are not only abutments, drills for implants, but also other parts used in prosthetics and implant procedures, that is, artificial tooth roots ( It can be used directly on fixtures, abutment screws and artificial teeth.

The zirconium oxide single crystals grown in accordance with one embodiment of the present invention can be used not only as a dental material, but also in orthopedic materials such as artificial bones or surgical bolts or nuts, surgical knives or surgical drills. It can be used and can be used with various scissors and combs.

In addition, the zirconium oxide single crystals grown in accordance with one embodiment of the present invention can be used as a special tool, such as an industrial knife as well as an end mill, which is an industrial material.

Thus, when used as a dental material using the zirconium oxide single crystals grown in accordance with an embodiment of the present invention, the grown single crystals do not rust, so inflammation does not occur, so the biocompatibility is very excellent. In addition, the grown single crystal has the same ivory color as that of artificial teeth, which is excellent in aesthetics and can be used for a long time because of its high mechanical strength, and has a technical effect of ingesting hot food without objection because of low thermal conductivity. In addition, there is an advantage that can minimize the heat generated during drilling in the alveolar bone due to the low frictional heat generated, thereby minimizing necrosis of the alveolar bone or gum.

In addition, the zirconium oxide single crystals grown in accordance with one embodiment of the present invention have high bending strength and fracture toughness, so that not only can they be mechanically precisely processed, but also ultrasonic and sand blast processing can be performed. Therefore, the grown single crystal can be used for various purposes such as a surgical knife, a drill used for precise and ultra-high speed machining, and a spacecraft component with excellent heat resistance.

As described above, the zirconium oxide single crystal and its manufacturing method have been described with reference to the preferred embodiments of the present invention, but a person skilled in the art does not depart from the spirit and scope of the present invention described in the claims below. It will be understood that various modifications and variations can be made in the present invention.

Claims (5)

ZrO ₂ : 96 ~ 92 wt% and Y ₂ O _{3 in} skull crucible growing single crystal by high frequency induction heating : Charging 4-8 wt% of raw material;
Placing a zirconium oxide metal particle or agglomeration of carbon in the skull crucible;
Applying power to a high frequency induction apparatus to melt the raw material charged starting from the zirconium oxide metal particles or carbon agglomerates inside the scull crucible;
Replenishing and supplying the raw material to the upper portion of the scull crucible while raising the induction coil outside the scull crucible at a speed of 1 to 20 mm / hr;
Cutting off the power of the high frequency induction apparatus when the zirconium oxide single crystal is completely grown in the scull crucible; And
Cooling the grown zirconium oxide single crystal at a cooling rate of 110 to 70 ° C / hr while maintaining the inside of the scull crucible; To
And a zirconium oxide single crystal for growing a zirconium oxide single crystal including a cubic and tetragonal crystal phase. The method of claim 1,
Wherein said cubic crystal phase forms a matrix and said tetragonal crystal phase is oriented in said matrix and is precipitated in a rod shape. The method of claim 2,
A method for growing a zirconium oxide single crystal in which a monoclinic (Monoclinic) crystal phase is partially mixed in the matrix. The method of claim 2,
The rod-shaped tetragonal crystal phase is a method of growing a zirconium oxide single crystal having an average diameter of 0.05 ~ 0.2 ㎛ and an average length of 0.5 ~ 1.5 ㎛ size. The method according to any one of claims 1 to 4,
Wherein the zirconium oxide single crystal has a fracture toughness of 1290 to 1603 ^{_{(kg f / mm 3/2}} ), the zirconium oxide single crystal growing method, characterized in that the bending strength of 329 to 352 (MPa).

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