KR101200590B1 - Method For Changing Color Of Zirconia - Google Patents

Abstract

Disclosed is a zirconia discoloration method capable of semi-permanently changing the color of zirconia with a simple heat treatment process. The discoloration method of the zirconia 100 according to the present invention is characterized by changing the color of the zirconia 100 by heat-treating the zirconia 100 in any one of a vacuum atmosphere, a reducing atmosphere, an oxidizing atmosphere.

Zirconia, Cubic Zirconia, Discoloration Method, Artificial Jewelry

Description

Method for changing color of zirconia {Method For Changing Color Of Zirconia}

The present invention relates to a method of discoloration of zirconia. More specifically, the present invention relates to a zirconia discoloration method capable of semi-permanently changing the color of zirconia by a simple heat treatment process.

Recently, zirconia has attracted attention as an artificial gemstone that can replace natural gemstones. In particular, cubic zirconia has been spotlighted as an artificial gemstone for jewelry, which is optically and physically very stable and good, and when processed precisely, it looks very beautiful due to the refraction or dispersion characteristics of light.

Zirconia is generally grown to have a cubic phase single crystal structure to be used as an artificial gemstone, which is essentially colorless and transparent. Therefore, in order to simulate colored natural gemstones such as emerald, sapphire, ruby, etc., an additional additional process for expressing color is required.

A general process used to express the color of zirconia is a process of mixing additives such as metal oxides with raw materials for growing cubic zirconia into single crystals.

 However, this process melts about 1 tonne of raw material in one process, melts by adding a large amount of electrical energy for a long time of about 120 hours or more, and then gradually solidifies the process to become directional solidification. Since it has to be controlled, there has been a problem of consuming a lot of energy structurally.

In addition, since only a single uniform color of zirconia is produced in large quantities, the burden of inventory is economically increased, and there is a problem in that it does not meet the needs of consumers who want rare and various colored gems.

An object of the present invention is to provide a zirconia discoloration method capable of semi-permanently changing the color of zirconia by a simple heat treatment process.

In addition, an object of the present invention is to provide a zirconia discoloration method that can reduce the cost burden of mass production of colored zirconia.

In addition, an object of the present invention is to provide a zirconia discoloration method that can produce a zirconia having a variety of colors to satisfy the individual needs of the consumer.

In order to achieve the above object, the zirconia discoloration method according to an embodiment of the present invention is characterized by changing the color of the zirconia by heat treatment in any one of a vacuum atmosphere, a reducing atmosphere, an oxidizing atmosphere. .

The zirconia may have a single crystal structure of cubic phase.

The zirconia can be produced by the skull melting method.

The zirconia is ZrO ₂ And Y ₂ O ₃ as a raw material.

The zirconia may further include at least one oxide of Ce, Pr, Po, Mn, Co, Ni, Fe.

The heat treatment temperature during the heat treatment may be in the range of 1,000 ℃ to 2,000 ℃.

In order to achieve the above object, the zirconia discoloration method according to an embodiment of the present invention comprises the steps of (a) preparing zirconia; And (b) first heat treating the zirconia.

In the step (b), the heat treatment atmosphere may be a vacuum atmosphere or a reducing atmosphere.

The heat treatment temperature in step (b) may be in the range of 1,000 ℃ to 2,000 ℃.

Heat treatment time in the step (b) may be in the range of 10 minutes to 60 minutes.

The zirconia discoloration method may further include (c) performing a second heat treatment of the zirconia.

In the step (c), the heat treatment atmosphere may be an oxidizing atmosphere.

Heat treatment temperature in the step (c) may be in the range of 500 ℃ to 2,000 ℃.

Heat treatment time in the step (c) may be in the range of 10 seconds to 60 minutes.

In the step (c), the heat treatment may be performed using a torch.

According to the present invention, the color of zirconia can be changed semi-permanently by a simple heat treatment process.

In addition, according to the present invention, the cost burden of producing a large amount of colored zirconia can be reduced.

In addition, according to the present invention, zirconia having various colors can be manufactured to satisfy individual demands of the consumer.

DETAILED DESCRIPTION OF THE INVENTION The following detailed description of the invention is described with reference to the accompanying drawings, which show by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention.

The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained.

DETAILED DESCRIPTION Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention.

1 to 3 are views showing the configuration of the discoloration method of the zirconia 100 according to an embodiment of the present invention.

First, referring to FIG. 1, a zirconia 100 having a predetermined shape is prepared. Zirconia (100) is an oxide of zirconium, has a high refractive index and good corrosion resistance, and is widely used as a ceramic material. The zirconia (100) is also a material that is widely attracted as a material such as dental implants.

Such zirconia 100 preferably has a cubic phase single crystal structure. Cubic zirconia (100) is similar to the general characteristics compared to the diamond, especially in terms of scattering is far superior to diamond or sapphire in terms of having a beautiful radiance than diamond. Therefore, when employing the cubic zirconia 100 as a component of the present invention it can maximize the discoloration effect of the present invention.

In addition, as a method of manufacturing the cubic zirconia 100, it is preferable to use the skull melting method which is a kind of the single crystal growth method. Since the skull melting method does not use a crucible, it may be suitable for producing cubic zirconia 100 having a very high forming temperature.

Meanwhile, as a raw material for manufacturing the zirconia 100 of the cubic phase, ZrO _{2 which} is an oxide of the zirconia 100 may be basically used, and a phase stabilizer for stabilizing the cubic phase may be additionally used. Various materials may be used as the phase stabilizer, but Y ₂ O ₃ , which is an oxide of yttrium, may be used, and the ratio of the phase stabilizer to the total composition may be appropriately determined according to the purpose of the present invention. It may change.

In addition, the metal oxide may be additionally mixed when the raw materials are mixed. This metal oxide may perform a function of expressing the color of the zirconia 100 to be produced later. For example, when cobalt (Co) oxides are mixed, violet zirconia (100) can be obtained later, and when green praseodymium (Pr) oxides are mixed, green zirconia (100) can be obtained. As the metal of the metal oxide to be mixed, various metals may be used, but preferably any one of Ce, Pr, Po, Mn, Co, Ni, and Fe may be used.

In addition, when the raw materials are mixed, in addition to the metal oxide, a material, such as MnO ₂ , may be added, ie, a color aid. By adding MnO ₂ , a solid solution such as ZrO ₂ and Y ₂ O ₃ may be formed to more easily produce the cubic zirconia 100.

On the other hand, in preparing a zirconia 100 having a predetermined shape, as shown in Figure 1, it is preferable to prepare a zirconia 100 having a gem shape. In this case, the heat treatment process described later can be performed at a low temperature, and the time required for the heat treatment process can be shortened. In order to prepare the zirconia 100 having a gem shape, a method of cutting the zirconia 100 into a round brilliant shape may be used. In addition, in consideration of productivity, the zirconia 100 will be preferably cut to match the shape of the jewelry to be finally manufactured.

Next, referring to FIG. 2, the prepared zirconia 100 is heat treated in a vacuum atmosphere or a reducing atmosphere. In order to distinguish the heat treatment process, that is, the heat treatment of the prepared zirconia 100 in a vacuum atmosphere or a reducing atmosphere from the second heat treatment process described later, it will be referred to as a first heat treatment process. Therefore, in the following specification, the first heat treatment process may mean heat treatment of the zirconia 100 in a vacuum atmosphere or a reducing atmosphere.

As mentioned above, during the first heat treatment, the zirconia 100 is heat treated in a vacuum atmosphere or a reducing atmosphere. It is to be understood here that the vacuum atmosphere includes not only a complete vacuum state in which no air is present, but also a state in which the vacuum degree is 100 mtorr or less. In addition, the reducing atmosphere may be understood to mean a state in which a reducing gas for allowing oxygen ions to escape from the surface of the zirconia 100 is supplied around the zirconia 100. Argon, nitrogen, helium or the like may be used as the reducing gas.

Preferably, the temperature range during the first heat treatment may be from about 1,000 ° C. to a temperature corresponding to 70% of the cubic zirconia 100 melting temperature, that is, to about 2,000 ° C. The first heat treatment within such a temperature range, it is difficult to implement the discoloration effect of the effect of the present invention when the first heat treatment at a temperature lower than 1,000 ℃, zirconia 100 when the first heat treatment at a temperature higher than 2,000 ℃ This is because a deformation of may be caused.

In addition, the first heat treatment time of the zirconia 100 is preferably 10 minutes to 60 minutes. The first heat treatment in such a time range is difficult to implement the discoloration effect, which is the effect of the present invention when the heat treatment for 10 minutes or less, and may cause excessive discoloration effect when heat treatment for 60 minutes or more.

In addition, the first heat treatment of the zirconia 100 is generally performed on the entire zirconia 100, but may be performed on a part of the zirconia 100 in some cases. As such, the first heat treatment is performed to express the color of the jewelry more colorfully.

As such, as the first heat treatment of the zirconia 100 occurs, the zirconia 100 may be discolored to a completely different color from the original color. For example, referring to FIGS. 1 and 2, the colorless zirconia 100 may be gradually discolored to black zirconia 100a by the first heat treatment process. The discoloration of the zirconia 100 may be interpreted to affect the color center by releasing oxygen ions from the surface of the zirconia 100 as the zirconia 100 is heat treated in a vacuum or inert atmosphere.

Meanwhile, referring to FIG. 3, a second heat treatment may be performed on the zirconia 100a discolored by the first heat treatment process. The second heat treatment may mean heat treatment in an oxidizing atmosphere. Here, the oxidizing atmosphere may refer to a state in which a gas containing oxygen atoms is supplied around the first heat treated zirconia 100a, and more specifically, gases such as O ₂ , H ₂ O, CO, CO _2, and the like may be used. It may refer to a state supplied around the first heat treated zirconia 100a. Therefore, heat treatment in an oxidizing atmosphere may mean heat treatment in air.

At this time, the temperature range in which the first heat-treated zirconia 100a is second heat-treated is preferably 500 ° C. to 2,000 ° C. Similar to what was mentioned above in connection with the first heat treatment temperature, it is difficult to realize a discoloration effect when the second heat treatment is performed at a temperature lower than 500 ° C., and the first heat treated zirconia (the second heat treatment at a temperature higher than 2,000 ° C. This is because deformation of 100a) can be caused.

In addition, the second heat treatment time of the first heat treated zirconia 100a may be 10 seconds to 60 minutes. As such, the second heat treatment process may be performed in a shorter time than the first heat treatment process. This may be related to the fact that one of the purposes of the second heat treatment process is to control the degree of discoloration of the first heat treated zirconia 100a in more detail.

Meanwhile, as shown in FIG. 3, the second heat treatment process may be performed by a combustion device, that is, a torch 200, which burns acetylene gas to generate a high temperature flame. In this case, there is an advantage that the second heat treatment process can be performed in a faster time. The type, size, etc. of the torch 200 used in the second heat treatment process are not particularly limited, and various types of torch 200 may be used in the second heat treatment process.

Also, similarly to the first heat treatment process, the second heat treatment may be performed on the entire first heat treated zirconia 100a, but in some cases, the second heat treatment may be performed on a part of the first heat treated zirconia 100a. It may be done.

By the second heat treatment process, the color of the first heat treated zirconia 100a may be changed again. For example, as illustrated in FIGS. 2 and 3, the color of the zirconia 100a that has been changed to black by the first heat treatment may be changed to a color that is close to the colorlessness before the first heat treatment, and gray. This may mean that the chroma is increased again by the second heat treatment process. The color change of the zirconia (100a) by the second heat treatment process is a mechanism opposite to the mechanism described in relation to the first heat treatment process, that is, the oxygen ions enter the surface of the zirconia (100a) affects the color center It can be interpreted as occurring because of a cycle.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are intended to illustrate the present invention in detail, it is to be understood that the present invention is not limited by the following examples and that various modifications and applications are possible within the scope of the following claims.

(Example)

Hereinafter, a method of discoloring zirconia according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

4 to 7 are photographs for explaining a method of discoloration of zirconia according to an embodiment of the present invention.

First, cubic zirconia single crystals were prepared by the skull melting method. As a raw material for preparing single crystal zirconia, a material was prepared in which 50 to 90 wt% ZrO ₂ and 10 to 50 wt% Y ₂ O ₃ were mixed when the total composition weight was 100 wt%. Next, the mixture was filled into a skull vessel, installed in a high frequency induction heater, and zirconia having a colorless cubic phase single crystal structure was prepared using an oscillation frequency of 200 to 500 kHz. Thereafter, the prepared single crystal zirconia was processed into specimens having a width of 5 mm, a length of 5 mm, and a thickness of 5 mm, and the surface of the processed specimen was polished to have a surface roughness of 0.002 μm, thereby preparing a specimen of colorless single crystal zirconia as shown in FIG. 4. It was.

Next, the prepared single crystal zirconia was heat-treated in a vacuum atmosphere. As a result of heat treatment at a heat treatment temperature of 1,200 ° C. for about 30 minutes, as shown in FIG. 5, zirconia which was colorless was changed to gray. As a result of further heat treatment for 30 minutes under the same conditions, gray single crystal zirconia was discolored to completely black as shown in FIG. 6.

Next, black single crystal zirconia was heated with an oxygen torch for about 3 minutes in the atmosphere. As a result, the color of the single crystal zirconia was discolored to the color before the first heat treatment, as shown in FIG.

In addition, although not shown in detail in Figures 5 to 7, it could be confirmed that the above-described color change was uniformly proceeded to the inside. Furthermore, it was confirmed that the discolored color was maintained for about 100 days or more at room temperature. From these results, it was confirmed that the discoloration process by the heat treatment was semi-permanent.

The above discoloration process gradually progressed over time, and accordingly, if the time for heat treatment in a vacuum atmosphere or the time for heating with an oxygen torch is properly adjusted, artificial gemstones having more various colors can be produced. there was.

8 is a photograph showing a state of single crystal zirconia of cubic phase having various colors.

FIG. 8 (a) is a photograph showing a purple cubic single crystal zirconia prepared by the same method as described above by mixing ZrO ₂ with 8 wt% of a phase stabilizer Y ₂ O ₃ and adding a metal oxide CoO.

FIG. 8 (b) shows a green cubic phase single crystal zirconia prepared by the same method as described above by mixing ZrO ₂ with a phase stabilizer Y ₂ O ₃ at 8% by weight and adding a metal oxide Pr ₆ O ₁₁ . It is a photograph.

FIG. 8 (c) shows light yellow cubic single crystal zirconia prepared by the same method as described above by mixing ZrO ₂ with a phase stabilizer Y ₂ O ₃ at 8% by weight and adding a metal oxide Pr ₆ O ₁₁ . It is photograph to show.

FIG. 8 (d) shows a yellow cubic single crystal zirconia prepared by the same method as described above by mixing ZrO ₂ with 8 wt% of a phase stabilizer Y ₂ O ₃ and adding a metal oxide Pr ₆ O ₁₁ . It is a photograph.

FIG. 8 (e) is a tan-brown cubic prepared in the same manner as in the above-described example by mixing ZrO ₂ with a phase stabilizer Y ₂ O ₃ at 8% by weight, and adding a metal oxide Pr ₆ O ₁₁ and a coloring aid MnO ₂ . It is a photograph showing a phase single crystal zirconia.

8 (f) is a dark brown cubic zirconia prepared in the same manner as in the above-described example by mixing the phase stabilizer Y ₂ O ₃ with ZrO ₂ in 8 wt% and adding a metal oxide Pr ₆ O ₁₁ and a colorifacting agent MnO ₂ . It is a photograph showing a phase single crystal zirconia.

On the other hand, although not shown in Figure 8, as a result of the heat treatment in the same manner as described above for the colored cubic zirconia of the color produced as described above, it was confirmed that the color of the cubic zirconia is also discolored. More specifically, when the heat treatment in a vacuum atmosphere it was confirmed that the color of the zirconia gradually changes to black, and when heated with an oxygen torch it was confirmed that the color returned to the original.

From the above results, it was confirmed that the zirconia discoloration method according to the present invention can be widely used as a discoloration method of artificial jewelry with high added value.

The zirconia discoloration method according to the present invention has the advantage that the color of the zirconia can be changed semi-permanently by a simple heat treatment process.

In addition, the zirconia discoloration method according to the present invention has the advantage that it can be discolored to have a variety of colors by arbitrarily adjusting the heat treatment time for the colored zirconia that already has a color by the impurities mixed during manufacturing.

In addition, the zirconia discoloration method according to the present invention can not only perform a discoloration process to large single crystal zirconia, but also discolor to a pattern having a local or predetermined shape instead of the entire surface of the zirconia, as well as the art of jewelry. There is an advantage that can be adopted.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken in conjunction with the present invention. Variations and changes are possible. Such modifications and variations are intended to fall within the scope of the invention and the appended claims.

1 to 3 are views showing the configuration of the discoloration method of the zirconia 100 according to an embodiment of the present invention.

4 to 7 are photographs for explaining a method of discoloration of zirconia according to an embodiment of the present invention.

8 is a photograph showing a state of single crystal zirconia of cubic phase having various colors.

<Explanation of symbols for the main parts of the drawings>

100, 100a, 100b: zirconia

200: torch

Claims (15)

(a) preparing zirconia; (b) first heat treating the zirconia; And (c) a second heat treatment of the zirconia Discoloration method of zirconia characterized in that it comprises a. The method of claim 1, The zirconia discoloration method of zirconia characterized in that it has a cubic phase single crystal structure. The method of claim 1, The zirconia discoloration method of zirconia, characterized in that produced by the skull melting method. The method of claim 3, The zirconia is ZrO ₂ And Y ₂ O ₃ as a raw material. 5. The method of claim 4, The zirconia discoloration method of zirconia further comprises at least one oxide of Ce, Pr, Po, Mn, Co, Ni, Fe ,. delete delete The method of claim 1, The heat treatment atmosphere in step (b) is a zirconia discoloration method, characterized in that the vacuum atmosphere or reducing atmosphere. The method of claim 1, In the step (b), the heat treatment temperature is a color change method of zirconia, characterized in that in the range of 1,000 ℃ to 2,000 ℃. The method of claim 1, In the step (b), the heat treatment time is a color change method of zirconia, characterized in that in the range of 10 minutes to 60 minutes. delete The method of claim 1, In the step (c), the heat treatment atmosphere is a zirconia discoloration method, characterized in that the oxidizing atmosphere. The method of claim 1, The heat treatment temperature in the step (c) is a zirconia discoloration method, characterized in that in the range of 500 ℃ to 2,000 ℃. The method of claim 1, The heat treatment time in the step (c) is a zirconia discoloration method, characterized in that in the range of 10 seconds to 60 minutes. The method of claim 1, Heat treatment in the step (c) is a zirconia discoloration method characterized in that it is carried out using a torch (torch).

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