KR102390133B1 - Method for producing colored zirconia with mechanical properties - Google Patents

Abstract

The present invention includes the steps of preparing a zirconia powder, molding the zirconia powder, pre-sintering the molded zirconia powder, immersing the pre-sintered result in a metal chloride solution to color the colored zirconia powder, It relates to a method for producing colored zirconia, comprising the steps of drying the resultant and sintering the dried colored resultant. According to the present invention, it is possible to manufacture colored zirconia having a color suitable for the color of teeth while exhibiting excellent strength.

Description

Method for producing colored zirconia with improved physical properties {Method for producing colored zirconia with mechanical properties}

The present invention relates to a method for producing colored zirconia, and more particularly, to a method for producing colored zirconia having a color suitable for tooth color while exhibiting excellent strength.

Zirconia (zirconia, ZrO ₂ ) refers to zirconium oxide, and has excellent heat resistance, heat insulation, corrosion resistance, and excellent mechanical properties. Due to these excellent properties, zirconia has been used for glass, refractory materials for iron making, wear-resistant parts, and cutting parts. In addition, due to its high biocompatibility, chemical stability, and esthetics, it began to be used as a medical material in 1969, and has been used as a dental material since 1990, including cores, abutments, crowns, and bridges. It is used in various products such as bridges) and orthodontic brackets. Recently, the CAD/CAM method has been introduced, making it possible to produce more accurate and various types of products, and thus the application is increasing in a wider field.

Zirconia exists in three crystal structures: monoclinic, tetragonal, and cubic, depending on the temperature. From room temperature to below 1170℃, monoclinic, from 1170℃ to 2370℃, tetragonal, and above 2370℃, cubic.

In the process of cooling after sintering, a phase transition occurs from a tetragonal phase to a monoclinic phase, resulting in volume expansion resulting in microcracks and deterioration of physical properties. To solve this problem, if stabilizers such as yttria (Y ₂ O ₃ ), ceria (CeO ₂ ), and magnesia (MgO) are added to zirconia, the tetragonal or cubic phase is stabilized at room temperature to prevent deterioration of physical properties. can Yttria-stabilized tetragonal zirconium polycrystal (Y-TZP) using yttria as a stabilizer is widely used as a dental material.

Republic of Korea Patent Publication No. 10-1276616

An object of the present invention is to provide a method for producing colored zirconia having a color suitable for tooth color while exhibiting excellent strength.

The present invention, (a) preparing the zirconia powder, (b) molding the zirconia powder, (c) pre-sintering the molded zirconia powder, (d) the pre-sintered result is a metal A step of coloring by immersion in a chloride solution, (e) drying the colored product, and (f) sintering the dried colored product, wherein the metal chloride solution is composed of a FeCl ₃ solution and a MnCl ₂ solution It provides a method for producing colored zirconia, characterized in that it comprises one or more materials selected from the group.

The zirconia powder may include yttria-stabilized tetragonal zirconium polycrystal (Y-TZP) powder.

The Y-TZP (yttria-stabilized tetragonal zirconium polycrystal) powder may include a partially stabilized zirconia (3Y-TZP) powder prepared by a co-precipitation method by adding 3 mol% of yttria.

The pre-sintering in step (c) is preferably performed at a temperature of 900 to 1100 °C.

The sintering in step (f) is preferably performed at a temperature of 1400 to 1650 °C.

In step (f), the sintering may include raising and maintaining a first temperature of 200 to 500° C. and raising and maintaining a second temperature of 1400 to 1650° C. higher than the first temperature.

The FeCl ₃ solution is preferably an aqueous solution having a concentration of 0.1 to 1M of FeCl ₃ .

The MnCl ₂ solution is preferably an aqueous solution having a concentration of 0.1 to 1M MnCl ₂ .

According to the present invention, it is possible to manufacture colored zirconia having a color suitable for the color of teeth while exhibiting excellent strength.

1 is a view showing an X-ray diffraction (XRD; X-ray diffraction) pattern of colored zirconia prepared according to Experimental Examples 1 to 6.
2 is a view showing X-ray diffraction (XRD) patterns of colored zirconia prepared according to Experimental Examples 7 to 12.
3 is a view showing X-ray diffraction (XRD) patterns of colored zirconia prepared according to Experimental Examples 13 to 18;
4 is a view showing the hardness of the colored zirconia prepared according to Experimental Examples 1 to 12.
5 is a view showing the hardness of the colored zirconia prepared according to Experimental Examples 13 to 18.
6 is a view showing the fracture toughness of the colored zirconia prepared according to Experimental Examples 1 to 12.
7 is a view showing the fracture toughness of the colored zirconia prepared according to Experimental Examples 13 to 18.
8 is a view showing the bending strength of the colored zirconia prepared according to Experimental Examples 1 to 12.
9 is a view showing the bending strength of the colored zirconia prepared according to Experimental Examples 13 to 18.
10A is a scanning electron microscope (SEM) photograph showing a Z specimen (partially stabilized zirconia (3Y-TZP) prepared by co-precipitation by adding 3 mol% of yttria), and FIG. It is a scanning electron microscope (SEM) photograph showing the colored zirconia (FO1) prepared according to the method, FIG. 10c is a scanning electron microscope (SEM) photograph showing the colored zirconia (FO6) prepared according to Experimental Example 6, FIG. 10D is an experimental example It is a scanning electron microscope (SEM) photograph showing the colored zirconia (MC1) prepared according to 16, and FIG. 10E is a scanning electron microscope (SEM) photograph showing the colored zirconia (MC3) prepared according to Experimental Example 18.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. However, the following examples are provided so that those of ordinary skill in the art can fully understand the present invention, and can be modified in various other forms, and the scope of the present invention is limited to the examples described below it is not going to be

In the detailed description or claims of the invention, when it is said that any one component "includes" another component, it is not construed as being limited to only the component unless otherwise stated, and other components are further added. It should be understood as being able to include

The method for producing colored zirconia according to a preferred embodiment of the present invention includes (a) preparing a zirconia powder, (b) molding the zirconia powder, (c) pre-sintering the molded zirconia powder (d) immersing the pre-sintered product in a metal chloride solution to color it, (e) drying the colored product, and (f) sintering the dried colored product, wherein the The metal chloride solution includes at least one material selected from the group consisting of a FeCl ₃ solution and a MnCl ₂ solution.

The zirconia powder may include yttria-stabilized tetragonal zirconium polycrystal (Y-TZP) powder.

The Y-TZP (yttria-stabilized tetragonal zirconium polycrystal) powder may include a partially stabilized zirconia (3Y-TZP) powder prepared by a co-precipitation method by adding 3 mol% of yttria.

The pre-sintering in step (c) is preferably performed at a temperature of 900 to 1100 °C.

The sintering in step (f) is preferably performed at a temperature of 1400 to 1650 °C.

In step (f), the sintering may include raising and maintaining a first temperature of 200 to 500° C. and raising and maintaining a second temperature of 1400 to 1650° C. higher than the first temperature.

The FeCl ₃ solution is preferably an aqueous solution having a concentration of 0.1 to 1M of FeCl ₃ .

The MnCl ₂ solution is preferably an aqueous solution having a concentration of 0.1 to 1M MnCl ₂ .

Hereinafter, a method for producing colored zirconia according to a preferred embodiment of the present invention will be described in more detail.

Y-TZP (yttria-stabilized tetragonal zirconium polycrystal) is preferred as a dental material due to its high strength, toughness, biocompatibility and aesthetics. Its usefulness has been limited. In addition, along with the improvement of living standards, aesthetic standards have also risen, so there is a demand for the development of colored zirconia of various colors suitable for the color of individual teeth.

Dental zirconia can be prepared by mixing and dipping. In the mixing method, colored zirconia is prepared by mixing zirconia powder with metal oxide powder for color expression and then sintering. In contrast, in the immersion method, a porous pre-sintered body is first made by partially sintering the zirconia powder at a temperature lower than the sintering temperature, and then the pre-sintered body is immersed in a coloring solution to give a color tone and then re-sintered to prepare colored zirconia.

In the method of mixing the metal oxide powder with the zirconia powder, various colors can be expressed by changing the composition according to the addition of the metal oxide. Fe ₂ O ₃ may be brown, (Zr,V)O ₂ may be yellow, Cr ₂ O ₃ may be green, (Al,Mn) ₂ O ₃ may be pink, and the like. However, in the method of mixing the metal oxide powder with the zirconia powder, since uniform mixing is difficult, the color tone of the zirconia block may become non-uniform, and mechanical properties such as strength may be reduced.

On the other hand, the method of expressing color tone by immersing the pre-sintered zirconia body in a coloring solution has little effect on mechanical properties while expressing color. However, mechanical properties may be deteriorated even by a method of preparing colored zirconia by immersion in a coloring solution.

To prepare a colored zirconia according to a preferred embodiment of the present invention, a zirconia powder is prepared. The zirconia powder may include yttria-stabilized tetragonal zirconium polycrystal (Y-TZP) powder. The Y-TZP (yttria-stabilized tetragonal zirconium polycrystal) powder may include a partially stabilized zirconia (3Y-TZP) powder prepared by a co-precipitation method by adding 3 mol% of yttria.

The zirconia powder is molded. For the molding, a method such as press molding or cold isostatic pressing (CIP) may be used. In addition, the molding may use a method such as sequentially performing press molding and cold hydrostatic pressing. The pressure forming is preferably performed at a pressure of 10 to 150 MPa, more preferably 30 to 120 MPa, and the cold hydrostatic pressure forming is preferably performed at a pressure of 150 to 250 MPa.

Pre-sinter the molded zirconia powder. The pre-sintering is preferably performed in an inert gas atmosphere such as nitrogen (N ₂ ), argon (Ar), or an oxidizing atmosphere such as oxygen or air. The pre-sintering is preferably performed at a temperature of 900 to 1100 °C, more preferably 950 to 1050 °C. It is preferable to increase the temperature up to the pre-sintering temperature at a temperature increase rate of 1 to 50 ° C./min. If the temperature increase rate is too slow, it takes a long time to decrease productivity. Since it can be added, it is preferable to raise the temperature at a temperature increase rate in the above range. In addition, the pre-sintering is preferably maintained at the pre-sintering temperature for 10 minutes to 24 hours. If the presintering time is too long, energy consumption is high, so it is not economical as well as it is difficult to expect any further sintering effect.

The pre-sintered result is colored by immersing it in a metal chloride solution. The metal chloride solution may include at least one material selected from the group consisting of a FeCl ₃ solution and a MnCl ₂ solution. The FeCl ₃ solution is preferably an aqueous solution having a concentration of 0.1 to 1M of FeCl ₃ . The MnCl ₂ solution is preferably an aqueous solution having a concentration of 0.1 to 1M MnCl ₂ . For the coloring, various methods such as a method of immersing the pre-sintered product in a metal chloride solution and a method of spraying a metal chloride solution on the surface of the pre-sintered product may be used.

The colored result is dried. The drying is preferably performed at a temperature of about 20 to 90 °C.

The dried coloring result is sintered. The sintering is preferably performed in an inert gas atmosphere such as nitrogen (N ₂ ), argon (Ar), or an oxidizing atmosphere such as oxygen or air. The sintering is preferably performed at a temperature of 1400 to 1650 °C, more preferably 1450 to 1600 °C. If the sintering temperature is less than 1400 ℃, the thermal or mechanical properties of the sintered body may be poor due to incomplete sintering. This may not be good. It is preferable to increase the temperature up to the sintering temperature at a temperature increase rate of 1 to 50 ° C./min. If the temperature increase rate is too slow, it takes a long time to decrease productivity. Therefore, it is preferable to raise the temperature at a temperature increase rate in the above range. In addition, the sintering is preferably maintained at the sintering temperature for 10 minutes to 24 hours. If the sintering time is too long, energy consumption is high, so it is uneconomical and it is difficult to expect any further sintering effect.

The sintering may include heating and maintaining a first temperature of 200 to 500°C and raising and maintaining a second temperature of 1400 to 1650°C higher than the first temperature.

Hereinafter, experimental examples according to the present invention are specifically presented, and the present invention is not limited to the experimental examples presented below.

In the experimental examples, 3Y-TZP (3mole% Yttria-stabilized Tetragonal Zirconia Polycrystals) powder was mixed with colored zirconia prepared by directly mixing metal oxide powder of Fe ₂ O ₃ and MnO ₂ , and a pre-sintered 3Y-TZP block with FeCl ₃ , A method for preparing colored zirconia with excellent mechanical stability is presented by comparatively analyzing the chromaticity and mechanical properties of the colored zirconia prepared by immersion in a metal chloride solution of MnCl ₂ .

<Experimental Example 1>

Partially stabilized zirconia (3Y-TZP) powder (TZ-3YB-E, Tosoh, Japan) prepared by a co-precipitation method by adding 3 mol% of yttria was prepared.

For the production of colored zirconia by mixing metal oxide, 0.01wt% of Fe ₂ O ₃ powder (metal oxide) was added to the 3Y-TZP powder, and the starting material (3Y-TZP powder 99.99wt%, Fe ₂ O ₃ powder 0.01wt%) ) was prepared, and the starting material was ball-milled for 24 hours and then dried in the air for 12 hours.

After classifying the dried starting material (mixed powder) with a sieve of 325mesh, uniaxially press-molded with a pressure of 100MPa to form a disc-shaped molded body with a diameter of 20mm and an average thickness of 3mm, a width of 5.8mm and a length of 34.8mm, And each bar-shaped molded body having a size of 4.3 mm in thickness was manufactured.

The molded body was charged into an electric furnace (Bell type supper kanthal furnace, AH JEON INDUSTRIAL CO., LTD., KOREA), the temperature was raised to 300°C at a heating rate of 10°C/min, and the temperature was maintained at 300°C for 1 hour, 10 The temperature was raised to 1500°C at a temperature increase rate of ℃/min, maintained at 1500°C for 2 hours, sintered under atmospheric pressure, and furnace cooled to obtain colored zirconia. Hereinafter, the colored zirconia prepared by adding 0.01wt% of Fe ₂ O ₃ powder according to Experimental Example 1 is named 'FO1'.

<Experimental Example 2>

Experimental Example 1 except that the starting material (3Y-TZP powder 99.97wt%, Fe ₂ O ₃ powder 0.03wt%) was prepared by adding 0.03wt% of Fe ₂ O ₃ powder (metal oxide) to 3Y-TZP powder A colored zirconia was obtained by performing the experiment in the same manner as in the above. Hereinafter, the colored zirconia prepared by adding 0.03wt% of Fe ₂ O ₃ powder according to Experimental Example 2 is called 'FO2'.

<Experimental Example 3>

Experimental Example 1 above except that 0.05wt% of Fe ₂ O ₃ powder (metal oxide) was added to 3Y-TZP powder to prepare a starting material (3Y-TZP powder 99.95 wt%, Fe ₂ O ₃ powder 0.05 wt%) A colored zirconia was obtained by performing the experiment in the same manner as in the above. Hereinafter, the colored zirconia prepared by adding 0.05wt% of Fe ₂ O ₃ powder according to Experimental Example 3 is called 'FO3'.

<Experimental Example 4>

Experimental Example 1, except that 0.1wt% of Fe ₂ O ₃ powder (metal oxide) was added to 3Y-TZP powder to prepare a starting material (3Y-TZP powder 99.9wt%, Fe ₂ O ₃ powder 0.1wt%) A colored zirconia was obtained by performing the experiment in the same manner as in the above. Hereinafter, the colored zirconia prepared by adding 0.1wt% of Fe ₂ O ₃ powder according to Experimental Example 4 is named 'FO4'.

<Experimental Example 5>

Experiment in the same manner as in Experimental Example 1, except that 0.3wt% of Fe ₂ O ₃ powder was added to 3Y-TZP powder to prepare starting materials (3Y-TZP powder 99.7 wt%, Fe ₂ O ₃ powder 0.3wt%) to obtain colored zirconia. Hereinafter, the colored zirconia prepared by adding 0.3wt% of Fe ₂ O ₃ powder according to Experimental Example 5 is named 'FO5'.

<Experimental Example 6>

Experimental Example 1, except that 0.5wt% of Fe ₂ O ₃ powder (metal oxide) was added to 3Y-TZP powder to prepare a starting material (3Y-TZP powder 99.5 wt%, Fe ₂ O ₃ powder 0.5 wt%) A colored zirconia was obtained by performing the experiment in the same manner as in the above. Hereinafter, the colored zirconia prepared by adding 0.5wt% of Fe ₂ O ₃ powder according to Experimental Example 6 is named 'FO6'.

<Experimental Example 7>

Partially stabilized zirconia (3Y-TZP) powder (TZ-3YB-E, Tosoh, Japan) prepared by a co-precipitation method by adding 3 mol% of yttria was prepared.

For the production of colored zirconia by mixing metal oxide, 0.01wt% of MnO ₂ powder (metal oxide) was added to the 3Y-TZP powder to prepare a starting material (3Y-TZP powder 99.99wt%, MnO ₂ powder 0.01wt%) and , The starting material was ball-milled for 24 hours and then dried in the air for 12 hours.

After classifying the dried starting material (mixed powder) with a sieve of 325mesh, uniaxially press-molded with a pressure of 100MPa to form a disc-shaped molded body with a diameter of 20mm and an average thickness of 3mm, a width of 5.8mm and a length of 34.8mm, And each bar-shaped molded body having a size of 4.3 mm in thickness was manufactured.

The molded body was charged into an electric furnace (Bell type supper kanthal furnace, AH JEON INDUSTRIAL CO., LTD., KOREA), the temperature was raised to 300°C at a heating rate of 10°C/min, and the temperature was maintained at 300°C for 1 hour, 10 The temperature was raised to 1500°C at a temperature increase rate of ℃/min, maintained at 1500°C for 2 hours, sintered under atmospheric pressure, and furnace cooled to obtain colored zirconia. Hereinafter, the colored zirconia prepared by adding 0.01wt% of MnO ₂ powder according to Experimental Example 7 is called 'MO1'.

<Experimental Example 8>

3Y-TZP powder MnO ₂ powder (metal oxide) 0.03wt% was added to prepare a starting raw material (3Y-TZP powder 99.97wt%, MnO ₂ powder 0.03wt%) Experiment in the same manner as in Experimental Example 7 to obtain colored zirconia. Hereinafter, the colored zirconia prepared by adding 0.03wt% of MnO ₂ powder according to Experimental Example 8 is called 'MO2'.

<Experimental Example 9>

The same experiment as in Experimental Example 7, except that 0.05wt% of MnO ₂ powder (metal oxide) was added to 3Y-TZP powder to prepare a starting material (3Y-TZP powder 99.95wt%, MnO ₂ powder 0.05wt%) to obtain colored zirconia. Hereinafter, the colored zirconia prepared by adding 0.05wt% of MnO ₂ powder according to Experimental Example 9 is called 'MO3'.

<Experimental Example 10>

The same experiment as in Experimental Example 7, except that 0.1wt% of MnO ₂ powder (metal oxide) was added to 3Y-TZP powder to prepare a starting material (3Y-TZP powder 99.9wt%, MnO ₂ powder 0.1wt%) to obtain colored zirconia. Hereinafter, the colored zirconia prepared by adding 0.1wt% of MnO ₂ powder according to Experimental Example 10 is called 'MO4'.

<Experimental Example 11>

3Y-TZP powder (metal oxide) 0.3wt% of MnO ₂ powder (metal oxide) was added to prepare the starting material (3Y-TZP powder 99.7wt%, MnO ₂ powder 0.3wt%), except for preparing the same experiment as in Experimental Example 7 to obtain colored zirconia. Hereinafter, the colored zirconia prepared by adding 0.3wt% of MnO ₂ powder according to Experimental Example 11 is called 'MO5'.

<Experimental Example 12>

The same experiment as in Experimental Example 7, except that 0.5wt% of MnO ₂ powder (metal oxide) was added to 3Y-TZP powder to prepare a starting material (3Y-TZP powder 99.5wt%, MnO ₂ powder 0.5wt%) to obtain colored zirconia. Hereinafter, the colored zirconia prepared by adding 0.5wt% of MnO ₂ powder according to Experimental Example 12 is called 'MO6'.

<Experimental Example 13>

Partially stabilized zirconia (3Y-TZP) powder (TZ-3YB-E, Tosoh, Japan) prepared by a co-precipitation method by adding 3 mol% of yttria was prepared.

For the production of colored zirconia through immersion in a coloring solution, the 3Y-TZP powder was uniaxially press-molded at a pressure of 100 MPa, and then maintained at 1000° C. for 2 hours to prepare a pre-sintered specimen. The pre-sintered specimen was colored by immersing it in 0.1M FeCl ₃ aqueous solution (metal chloride solution) for 3 minutes, then taken out to remove the solution on the surface of the specimen and then dried.

The color classification of the specimen according to the concentration of the coloring solution was analyzed as follows. Natural teeth are defined as L*, a*, and b* values in CIE, where L* is proportional to the brightness of the Munsell system, indicating achromatic characteristics, and a*, b* values indicate the coordinates of chromaticity. In general, an increase in a* shows red, a decrease in green, an increase in b*, yellow, and a decrease in blue.

The colored specimen was heated to 300°C at a heating rate of 10°C/min in an electric furnace and maintained at 300°C for 1 hour, then heated to 1500°C at a heating rate of 10°C/min and maintained at 1500°C for 2 hours. After atmospheric pressure sintering and furnace cooling, colored zirconia was obtained. Hereinafter, the colored zirconia prepared by immersion in 0.1M FeCl ₃ aqueous solution according to Experimental Example 13 is called 'FC1'.

<Experimental Example 14>

3Y-TZP powder was uniaxially press-molded at a pressure of 100 MPa, and then the pre-sintered specimen obtained by maintaining at 1000 ° C. for 2 hours was immersed in 0.3 M FeCl ₃ aqueous solution (metal chloride solution) for 3 minutes and colored except that The experiment was performed in the same manner as in Experimental Example 13 to obtain colored zirconia. Hereinafter, the colored zirconia prepared by immersion in 0.3M FeCl ₃ aqueous solution according to Experimental Example 14 is called 'FC2'.

<Experimental Example 15>

After uniaxial pressure molding of 3Y-TZP powder at a pressure of 100 MPa, the pre-sintered specimen obtained by maintaining at 1000 ° C. for 2 hours was immersed in 0.5 M FeCl ₃ aqueous solution (metal chloride solution) for 3 minutes and colored except that The experiment was performed in the same manner as in Experimental Example 13 to obtain colored zirconia. Hereinafter, the colored zirconia prepared by immersion in 0.5M FeCl ₃ aqueous solution according to Experimental Example 15 is called 'FC3'.

<Experimental Example 16>

Partially stabilized zirconia (3Y-TZP) powder (TZ-3YB-E, Tosoh, Japan) prepared by a co-precipitation method by adding 3 mol% of yttria was prepared.

For the production of colored zirconia through immersion in a coloring solution, the 3Y-TZP powder was uniaxially press-molded at a pressure of 100 MPa, and then maintained at 1000° C. for 2 hours to prepare a pre-sintered specimen. The pre-sintered specimen was colored by immersing it in 0.1M MnCl ₂ aqueous solution (metal chloride solution) for 3 minutes, and then taken out to remove the solution on the surface of the specimen and then dried.

The color classification of the specimen according to the concentration of the coloring solution was analyzed as follows. Natural teeth are defined as L*, a*, and b* values in CIE, where L* is proportional to the brightness of the Munsell system, indicating achromatic characteristics, and a*, b* values indicate the coordinates of chromaticity. In general, an increase in a* shows red, a decrease in green, an increase in b*, yellow, and a decrease in blue.

The colored specimen was heated to 300°C at a heating rate of 10°C/min in an electric furnace and maintained at 300°C for 1 hour, then heated to 1500°C at a heating rate of 10°C/min and maintained at 1500°C for 2 hours. After atmospheric pressure sintering and furnace cooling, colored zirconia was obtained. Hereinafter, the colored zirconia prepared by immersion in 0.1M MnCl ₂ aqueous solution according to Experimental Example 16 is called 'MC1'.

<Experimental Example 17>

3Y-TZP powder was uniaxially press-molded at a pressure of 100 MPa, and then the pre-sintered specimen obtained by maintaining at 1000 ° C. for 2 hours was immersed in 0.3 M MnCl ₂ aqueous solution (metal chloride solution) for 3 minutes and colored except that The experiment was carried out in the same manner as in Experimental Example 16 to obtain colored zirconia. Hereinafter, the colored zirconia prepared by immersing in 0.3M MnCl ₂ aqueous solution according to Experimental Example 17 is called 'MC2'.

<Experimental Example 18>

3Y-TZP powder was uniaxially press-molded at a pressure of 100 MPa, and then the pre-sintered specimen obtained by maintaining at 1000 ° C. for 2 hours was immersed in 0.5 M MnCl ₂ aqueous solution (metal chloride solution) for 3 minutes and colored except that The experiment was carried out in the same manner as in Experimental Example 16 to obtain colored zirconia. Hereinafter, the colored zirconia prepared by immersion in 0.5M MnCl ₂ aqueous solution according to Experimental Example 18 is named 'MC3'.

The density of the colored zirconia prepared according to Experimental Examples 1 to 18 was measured using the Archimedes method, and the strength measurement was 3 points using a universal tester (RB 301, R&B INC., KOREA) according to the standard of KS L1591. The bending strength was measured.

The surface of the colored zirconia prepared according to Experimental Examples 1 to 18 was finally polished with diamond paste up to 1 μm after lapping, and 98N using a Vickers hardness tester (ZHU2.5, Zwick/Rowll, Germany). A load was applied to measure the hardness. The fracture toughness was calculated using the IF (Indentational Fracture) method by measuring the crack length of the indentation during hardness measurement.

In order to confirm the phase change or the generation of a secondary phase of the colored zirconia prepared according to Experimental Examples 1 to 18, it was analyzed using an X-ray diffraction analyzer (SMARTLAB, Rigaku, JAPAN). The diffraction angle was measured at 5°/min from 20° to 80°.

Then, the polished specimen was subjected to thermal etching at 1400° C. for 1 hour, and the microstructure was observed at 15 kV and 15000 magnification with a scanning electron microscope (JSM-7000F, JEOL, JAPAN).

Spectrophotometric equipment (V-570, JASCO, JAPAN) was measured at a viewing angle of 10° in the SCE method close to the human eye using the D65 light source, which is the ISO standard of the Commission Internationale de I'Eclairage (CIE). Color L*, a*, b* values were obtained at random positions for each specimen, and the color difference values were calculated and expressed in the CIE (L*a*b*) color space system.

1 is a view showing an X-ray diffraction (XRD; X-ray diffraction) pattern of colored zirconia prepared according to Experimental Examples 1 to 6, and FIG. 2 is a colored zirconia prepared according to Experimental Examples 7 to 12. It is a view showing an X-ray diffraction (XRD) pattern of zirconia, and FIG. 3 is a view showing an X-ray diffraction (XRD) pattern of colored zirconia prepared according to Experimental Examples 13 to 18.

1 to 3 , the diffraction peaks of all colored zirconia were 30.2°, 34.5°, 35.2°, 50.2°, 50.6°, 59.3°, and 60°, and the difference in the crystal phase according to the change in composition there was no All peaks were analyzed as tetragonal phases of zirconia, and peaks due to monoclinic phases or secondary phases did not appear.

As a result of measuring the relative density with respect to the theoretical density of the colored zirconia prepared according to Experimental Examples 1 to 18, the density of all specimens was at least 98.4% from 5.95 to 6.03 when compared to the theoretical density of 6.05. . The colored zirconia prepared by the mixing method (the colored zirconia prepared according to Experimental Examples 1 to 12) increased relative density as a small amount of metal oxide was added, and then decreased when 0.1 wt% or more was added. In contrast, the colored zirconia prepared by the immersion method (the colored zirconia prepared according to Experimental Examples 13 to 18) showed a relatively constant increase of 99.0% or more as the concentration of the metal chloride solution increased.

4 is a diagram showing the hardness of the colored zirconia prepared according to Experimental Examples 1 to 12, and FIG. 5 is a diagram showing the hardness of the colored zirconia prepared according to Experimental Examples 13 to 18. 4 and 5, 'Z' represents partially stabilized zirconia (3Y-TZP) prepared by co-precipitation by adding 3 mol% of yttria (hereinafter, referred to as 'Z specimen').

4 and 5, the hardness value of the Z specimen was 13.13 GPa, and the amount of metal oxide added to both the colored zirconia prepared according to Experimental Examples 1 to 4 and the colored zirconia prepared according to Experimental Examples 7 to 10 Up to 0.1wt%, a value similar to the hardness of the Z specimen was shown, but according to Experimental Examples 5, 6, 11, and 12, as the amount of the metal oxide was increased to 0.3wt% or more, it gradually decreased to 0.3~0.5 GPa. decreased.

The colored zirconia prepared according to Experimental Examples 13 to 18 showed a hardness similar to that of the Z specimen. FeCl ₃ Colored zirconia prepared by immersion in an aqueous solution (colored zirconia prepared according to Experimental Examples 13 to 15) and MnCl ₂ Colored zirconia prepared by immersion in an aqueous solution (Colored zirconia prepared according to Experimental Examples 16 to 18) ) means that it is possible to manufacture colored zirconia without a decrease in strength compared to the Z specimen.

6 is a view showing the fracture toughness of the colored zirconia prepared according to Experimental Examples 1 to 12, and FIG. 7 is a diagram showing the fracture toughness of the colored zirconia prepared according to Experimental Examples 13 to 18. 6 and 7, 'Z' represents partially stabilized zirconia (3Y-TZP) prepared by co-precipitation by adding 3 mol% of yttria.

6 and 7 , when the mixing method was applied (Experimental Examples 1 to 12), fracture toughness was irregularly changed according to the amount of metal oxide added.

In contrast, the colored zirconia prepared according to Experimental Examples 13 to 18 showed a constant fracture toughness value even when the concentration of the metal chloride solution was changed.

8 is a view showing the bending strength of the colored zirconia prepared according to Experimental Examples 1 to 12, and FIG. 9 is a view showing the bending strength of the colored zirconia prepared according to Experimental Examples 13 to 18. 8 and 9, 'Z' represents partially stabilized zirconia (3Y-TZP) prepared by co-precipitation by adding 3 mol% of yttria.

Referring to FIGS. 8 and 9 , the strength of the Z specimen without mixing of metal oxide or immersion in metal chloride solution was measured to be 650.65 MPa.

In the case of the colored zirconia prepared according to Experimental Examples 13 to 18, the highest strength value was exhibited when the concentration of the metal chloride solution was 0.3M, and the colored zirconia prepared according to Experimental Examples 13 to 15 was At 673.17 MPa, the strength value of the colored zirconia prepared according to Experimental Examples 15 to 18 was relatively high compared to that of 625.78 MPa.

On the other hand, in the case of the colored zirconia prepared according to Experimental Examples 1 to 6, FO1 was 639.97 MPa, FO2 was 647.01 MPa, and FO3 was 662.75 MPa. There was no significant difference, but FO4 was 606.00 MPa, FO5 was 517.51 MPa, and FO6 was 397.16 MPa.

In addition, in the case of the colored zirconia prepared according to Experimental Examples 7 to 12, MO1 was 597.42 MPa, MO2 was 552.51 MPa, MO3 was 568.11 MPa, MO4 was 550.79 MPa, and MO5 was measured to be 554.30MPa, Z specimen It was analyzed that the strength was about 100 MPa lower than that of , but a significant decrease in strength of about 32% occurred at 445.84 MPa in MO6 containing many metal oxides.

The results of measuring the color coefficient (CIE) of the colored zirconia prepared according to Experimental Examples 1 to 18 are shown in Table 1 below.

Samples L* a* b* Z 91.93 -1.31 3.81 FO1 88.75 -1.85 4.01 FO2 88.41 -2.72 8.39 FO3 84.62 -1.65 10.39 FO4 81.40 -0.48 15.61 FO5 68.93 4.84 22.36 FO6 61.40 7.05 18.59 MO1 65.61 2.83 -0.61 MO2 58.66 3.05 -1.17 MO3 55.03 2.87 -1.61 MO4 49.36 2.39 -1.01 MO5 44.21 1.36 -0.83 MO6 42.59 1.28 -0.01 FC1 90.86 -2.78 10.38 FC2 84.51 -2.68 17.16 FC3 76.41 1.53 20.58 MC1 63.01 3.62 0.86 MC2 56.44 3.38 -0.82 MC3 45.39 3.29 0.67

It is known that the average color value of natural teeth is 64.33 ~ 78.02 for L*, 2.63 ~ 2.77 for a*, and 9.77 ~ 25.73 for b*. In the case of colored zirconia (MO1) prepared according to Experimental Example 7, based on the analysis value of the Z specimen, a* increased to 4.14, b* decreased to 4.42, respectively, and L* showed a value of 65.61. . In the case of colored zirconia (addition amount of metal oxide 0.01wt%) prepared according to Experimental Example 7, the average value most similar to natural teeth was shown, but according to Experimental Examples 8 to 12, as the amount of metal oxide added increased, L *, a*, b* values were all out of the average range of natural teeth.

In the colored zirconia prepared according to Experimental Example 5 (when the amount of metal oxide added was 0.3 wt%) and the colored zirconia prepared according to Experimental Example 5 (when the amount of added metal oxide was 0.5 wt%), a* was 6.15 and 8.36, respectively. increased, b* increased to 18.55 and 14.78, respectively, and L* showed values of 68.93 and 61.40, respectively, indicating the most similar average value to natural teeth.

In contrast, in the colored zirconia (FC1) prepared according to Experimental Example 15, a* increased to 2.84 based on the analysis value of the Z specimen, b* increased to 16.77, and L* showed a value of 76.41, respectively, It showed the most similar average value for natural teeth. In the colored zirconia (MC1) prepared according to Experimental Example 16, a* increased to 4.93, b* decreased by 2.95, and L* showed a value of 63.01, which is the most similar to natural teeth based on the analysis value of the Z specimen. Although the average value was shown, according to Experimental Examples 17 and 18, as the concentration of the metal chloride solution increased, the L*, a*, and b* values all deviated from the average range of natural teeth.

10A is a scanning electron microscope (SEM) photograph showing a Z specimen (partially stabilized zirconia (3Y-TZP) prepared by co-precipitation by adding 3 mol% of yttria), and FIG. It is a scanning electron microscope (SEM) photograph showing the colored zirconia (FO1) prepared in accordance with, Figure 10c is a scanning electron microscope (SEM) photograph showing the colored zirconia (FO6) prepared according to Experimental Example 6, Figure 10d is an experimental example It is a scanning electron microscope (SEM) photograph showing the colored zirconia (MC1) prepared according to 16, and FIG. 10E is a scanning electron microscope (SEM) photograph showing the colored zirconia (MC3) prepared according to Experimental Example 18.

Referring to FIGS. 10A to 10E , the average grain size was obtained from the obtained image using a line cutting method. The average grain size of the Z specimen was 0.405 μm, and it was analyzed that grains of about 0.4 μm in size were generated on average in FO1, FO2, and FO3. In the case of FO4, FO5, and FO6, as the amount of metal oxide was increased, grains grew, and it was determined that the average grain size of FO6 was up to 0.548㎛.

In a previous study, Matsui et al. (2008) reported that Y ³⁺ ions segregate along grain boundaries in YSZ, resulting in coarsening of grains by a solute-drag mechanism, Fangwei et al. (2012) ) reported that when a metal oxide is added, metal cations act the same as Y ³⁺ , and segregation is easier than Y ³⁺ , resulting in coarser grains.

FC1, FC2, FC3, MC1, MC2, and MC3 showed an average grain size of 0.4~0.442㎛ with no change in grain size depending on the metal chloride solution. As a result, it was confirmed through microstructure analysis that coarsening of grains was the cause of the aforementioned deterioration of mechanical properties.

Although it is very important for colored zirconia to harmonize with existing natural teeth according to the improvement of esthetics, commercial zirconia has disadvantages of high brightness and low saturation because it is close to white or ivory.

In these experimental examples, colored zirconia was prepared by mixing and dipping, and clinical suitability according to color tone and mechanical properties was also investigated. As a result, both the mixed method group (FO1 to FO6, MO1 to MO6) and the immersion method group (FC1 to FC3, MC1 to MC3) showed a fracture toughness distribution of 6 to 8 MPa·m ^0.5 , indicating the fracture toughness of zirconia used in clinical practice. value was satisfied. FO2 (when the amount of metal oxide added was 0.03 wt%) showed the highest fracture toughness of 7.6 MPa·m ^0.5 , while MO5 (when the amount of added metal oxide was 0.3 wt%) showed 7.5 MPa·m ^0.5 , The range of change according to the addition of metal oxide showed a maximum increase or decrease of 5 to 10%.

On the other hand, when the immersion method was applied, fracture toughness of 6.9 ~ 7.2 MPa·m ^0.5 was exhibited as the concentration of the metal chloride solution increased, indicating a relatively constant fracture toughness value.

The decrease in mechanical properties shown in the mixing method is due to the coarsening of the particles formed according to the amount of metal oxide added. The FC group (FC1, FC2, FC3) and MC group (MC1, MC2, MC3) to which the immersion method was applied were able to manufacture colored zirconia that satisfies the color tone and strength, but the FO group (FO1, FO2, FO3, FO1, FO2, FO3, FO4, FO5, and FO6) showed a decrease in mechanical properties at an amount of 0.3 to 0.5 wt% (amount of metal oxide added) having a suitable color tone. As a result, the colored zirconia prepared by the immersion method had higher and constant mechanical properties and suitable color tone than the colored zirconia prepared by the mixing method.

As mentioned above, although preferred embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various modifications are possible by those skilled in the art.

Claims (8)

(a) preparing a zirconia powder;
(b) forming the zirconia powder;
(c) pre-sintering the molded zirconia powder;
(d) coloring the pre-sintered product by immersing it in a metal chloride solution;
(e) drying the colored product; and
(f) sintering the dried coloring result;
The metal chloride solution includes at least one material selected from the group consisting of FeCl ₃ solution and MnCl ₂ solution,
In step (f), the sintering is performed at a temperature of 1400 to 1650 °C,
The sintering in step (f) is,
raising and maintaining a first temperature of 200 to 500 °C; and
Method for producing colored zirconia, characterized in that it comprises the step of heating and maintaining the second temperature of 1400 ~ 1650 ℃ higher than the first temperature.
The method of claim 1, wherein the zirconia powder comprises yttria-stabilized tetragonal zirconium polycrystal (Y-TZP) powder.
The colored zirconia (3Y-TZP) powder according to claim 2, wherein the Y-TZP (yttria-stabilized tetragonal zirconium polycrystal) powder comprises a partially stabilized zirconia (3Y-TZP) powder prepared by a co-precipitation method by adding 3 mol% of yttria. A method for producing zirconia.
The method of claim 1, wherein the pre-sintering in step (c) is performed at a temperature of 900 to 1100°C.
delete delete The method of claim 1, wherein the FeCl ₃ solution is an aqueous solution having a concentration of FeCl ₃ of 0.1 to 1M.
The method of claim 1, wherein the MnCl ₂ solution is an aqueous solution having a MnCl ₂ concentration of 0.1 to 1M.

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