JPH01264960A - Colored zirconia ceramics and its production - Google Patents

Abstract

PURPOSE:To obtain the title ceramics which has high strength and high toughness characteristics and is colored black or dark by sintering a molding consisting of a metal oxide, ZrO2 and stabilizer, then further calcining the molding in a C-contg. atmosphere thereby obtaining the specific compsn. CONSTITUTION:The molding having a required shape is formed from the raw material consisting of 0.1-10pts.wt. metal oxide (e.g.: Cr2O3, TiO2, etc.), 90-99.9 pts.wt. ZrO2 and the stabilizer (e.g.: Y2O3) and is subjected to a 1st calcination preferably in an oxidizing atmosphere to sinter the molding. This molding is then subjected to the 2nd calcination preferably at 1,100-1,650 deg.C in the C- contg. atmosphere. The title ceramics which consists of the coloring component of 0.1-10wt.% in terms of the metal oxide as the metal oxide and/or the reduction product thereof, the stabilizer and the ZrO2 contg. >=0.05wt.% and <0.2wt.% ZrC having <=0.1wt.% free C content and in which preferably about >=60mol% of the crystal phase of the ZrO2 consists of tetragonal crystals is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a colored zirconia ceramic which can be colored as desired with a coloring component consisting of a metal compound and a carbon component, and which has high strength and toughness properties, and a colored zirconia ceramic that has high strength and toughness properties. It is related to the manufacturing method.

[Prior art and its problems]

Recently, partially stabilized zirconia ceramics, which are zirconia ceramics containing a stabilizer within the required range, have been attracting attention, and are expected to have a wide range of uses due to their high strength and toughness properties.

On the other hand, colored zirconia ceramics in which this ceramic contains a colorant, and black zirconia ceramics in which a colorant and carbon are further contained have been proposed.

As the latter black zirconia ceramic, JP-A-59
-227770 has been proposed, and the colorants used for the ceramics include (1)...4a of the periodic table.
, at least one metal and/or alloy selected from group 5a and 6a metals and iron group metals, or (
2)...At least one compound selected from carbides, borides, silicides, and mutual solid solutions of metals in groups 4a, 5a+6a of the periodic table, and further (1) and (2).
) is proposed. This colorant contains carbon and/or graphite to promote sintering and facilitate black color tone control.

According to such black zirconia ceramics, (
When the colorant of 1) is contained, the metal component is contained in the zirconia ceramic, so it becomes a cermet,
This inhibits the sintering of zirconia itself, making it impossible to exhibit the original properties of zirconia, and, for example, making it impossible to obtain high strength and high toughness properties. On the other hand, when the coloring agent (2) is included, vacuum firing is used, but it is difficult to control the firing, and this makes it difficult to homogenize the atmosphere throughout the interior of the same firing furnace. or it becomes difficult to make the sintering conditions the same between individual firing furnaces, resulting in uneven coloring between the individual finished ceramics, and it is difficult to maintain the same level of high strength and toughness properties. The problem is that it cannot be obtained.

Further, according to this ceramic, carbon and/or graphite is contained in addition to the above-mentioned coloring agent to promote sintering and facilitate control of black or dark color tone.

However, when incorporating a carbon component in this way, since this component is included in the starting material, carbon may remain unreacted in the sintered body, or the sintered body may become porous. This causes a problem in that the strength deteriorates and it is difficult to obtain a mirror surface with a deep luster.

[Purpose of the invention]

The present invention has been devised in view of the above, and its object is to provide colored zirconia ceramics that can be colored as desired without uneven coloring among the individual pieces.

Another object of the present invention is to provide a colored zirconia ceramic having a smooth mirror surface with deep luster.

Still another object of the present invention is to provide a colored zirconia ceramic that can be colored without impairing the high strength and toughness properties of the partially stabilized zirconia ceramic itself.

Still another object of the present invention is the above-mentioned colored zirconia ceramic.
Our objective is to provide a manufacturing method for obtaining Nox.

Means for Solving Problem C] According to the present invention, a coloring component of 0.1 to 10% by weight, a stabilizer, 0.05% by weight or more and 0.05% by weight or more in terms of metal oxide.
Provided is a colored zirconia ceramic comprising zirconia containing less than 2% by weight of zirconium carbide and having a free carbon content of 0.1% by weight or less, and characterized in that the crystalline phase of the zirconia consists of tetragonal crystals. be done.

Further, according to the present invention, a molded body having a desired shape is formed from a raw material consisting of 0.1 to 10 parts by weight of a metal oxide, 90 to 99.9 parts by weight of zirconia, and a stabilizer, and then the first firing is performed. The compact is then sintered by a second firing in a carbon-containing atmosphere to produce a desired colored zirconia ceramic, which contains the reduction product of the metal oxide and 0.05% by weight or more and 0.
A method for producing a colored zirconia ceramic is provided, which contains less than 2% by weight of zirconium carbide, has a free carbon content of 0.1% by weight or less, and is composed of tetragonal zirconia crystals.

The colored zirconia ceramics of the present invention are partially stabilized zirconia ceramics (hereinafter referred to as ps
z ceramics) containing metal oxides and zirconium carbide as coloring components, and the base color tone is formed by the selection of the metal oxides, the amount added, and their reduction products, and the base color tone is created by the selection of the metal oxides, their addition amounts, and their reduction products. (
It is characterized by being blackened or darkened as desired depending on the content of ZrC).

Furthermore, the colored zirconia ceramics of the present invention have a lower ZrC content than the colored zirconia ceramics already proposed by the present inventor in Japanese Patent Application No. 61-311193. Another feature is that it is possible to blacken or darken a molded object of any size or shape without color unevenness.

In addition, this colored zirconia ceramic is a PSZ ceramic made of tetragonal crystals, and its characteristics are that it has high strength and high toughness properties, but its properties tend to deteriorate due to the addition of metal oxides, which are coloring components. To complement this, ZrC is contained to maintain high strength and high toughness characteristics.

First, according to the colored zirconia ceramics of the present invention,
Metal oxides and/or coloring components are added to PSZ ceramics.
Or its reduction product and ZrC are contained within a predetermined range to achieve desired coloration and high strength and toughness characteristics, and the total amount of metal oxide and/or its reduction product is If it is contained within the range of 0.1 to 10% by weight in terms of metal oxide, if it is less than 0.1% by weight, the desired coloring will be insufficient and color unevenness will easily occur. If the amount exceeds 10% by weight, high strength and toughness properties cannot be obtained.

Further, ZrC may be contained in a range of 0.05% by weight or more and less than 0.2% by weight, preferably 0.1% by weight or more and less than 0.2% by weight, less than 0.05% by weight. If so, blackening or darkening will not be achieved as desired.

The coloring components include group rVa of the periodic table, group Va, group ■a,
There are oxides of Group A and Group A elements, such as Cr, Co+ Fe, Ti, Mn+ V, Ni
There are oxides of However, these oxides may be reduced to carbides, simple metals, etc. by firing in a reducing atmosphere containing carbon.

Thus, according to the colored zirconia ceramics of the present invention containing the above-mentioned components, the inclusion of ZrC in a part of the coloring component results in a black color or a tendency for the coloring of the coloring component to darken, thereby meeting the requirements. Coloring is possible. For example, iridescent or metallic tones are N.
It can be obtained by adding iO, CoO, etc. and containing ZrC.

Furthermore, according to the present invention, in addition to the above-mentioned coloring, the blackening component ZrC is contained in the psz ceramics within a predetermined range, so that the psz ceramics can be colored black or dark as desired and have high strength. Another feature is that it has achieved high toughness.

That is, according to the PSZ ceramics of the present invention, the high strength and toughness properties tend to deteriorate due to the addition of coloring components, but when ZrC is included in the PSZ ceramics, the content of the coloring components is It becomes possible to reduce the amount of water and achieve desired coloration, thereby preventing the above-mentioned tendency toward deterioration.

In addition, when both ZrC and ZrO□ coexist within their respective predetermined ranges, strength and toughness can be increased, thereby complementing the tendency for high strength and high toughness properties to deteriorate due to the addition of coloring components. can do.

For that purpose, the amount of ZrC added should be 0.05% by weight or more,
It is preferable to set it to 0.1% by weight or more, and furthermore, Zr
The O content is related to the type of crystal phase, but it may be set within the range of 75 to 99.7% by weight.

The presence of tetragonal crystals in this ZrO2 is indispensable, and this brings about high strength and high toughness properties, and the proportion thereof in the total Zr02 crystal phase is 40 mol% or more, preferably 80%. It is preferable that the amount is mol% or more.

Furthermore, according to the above-mentioned PSZ ceramics, free carbon is a component that reduces high strength and high toughness characteristics, and its content is 0.1% by weight or less, preferably 0.0% by weight in the entire sintered body.
The content may be 5% by weight or less.

The present inventor measured the strength and toughness of colored zirconia ceramics having such a composition, and found that the strength and toughness were approximately 130 K.
A high strength property of "g/cm" and a high toughness property of about 15 MN/n+"" were obtained.

The colored zirconia ceramic thus obtained has strength and toughness comparable to conventionally known white PsZ ceramics, can be colored evenly by the coloring component and ZrC, and has a polished surface. In this case, it becomes a mirror surface with a deep luster.

Next, a manufacturing method for obtaining the colored zirconia ceramics of the present invention will be described.

The manufacturing method of the present invention involves firing in two stages.The first firing is a method to obtain PSZ ceramics containing metal oxides as coloring components, and then the second firing is performed on this PSZ ceramic. The method is characterized in that firing is performed to impregnate the interior of the PSz ceramic with a carbon component and to generate a reduction product of the metal oxide.

That is, first, the first firing (hereinafter referred to as the first firing)
According to the above, the Zr0z raw material, the metal oxide coloring component, and the stabilizer are mixed sufficiently uniformly in a ratio within a predetermined range, and then pressure-molded into a predetermined shape, and then
A colored ps'z ceramic molded body is obtained by firing at a temperature of 700°C, particularly 1350 to 1600°C.

The mixing ratio of the metal oxide and ZrO is such that the metal oxide is 0.
In the case of 1 to 10 parts by weight, ZrO□ is 90 to 99.9
It may be set within the range of parts by weight.

That is, if the amount of the metal oxide is less than 0.1 parts by weight, desired coloring cannot be achieved and color unevenness tends to occur, and if it exceeds 10 parts by weight, high strength and high toughness characteristics cannot be obtained.
Furthermore, if ZrO□ is less than 90 parts by weight, sintering is difficult and high strength and toughness characteristics cannot be obtained.

The metal oxide may be in any state of powder, liquid, or paste at the raw material stage, and its particle size is 0.
．． The particle diameter is preferably 0.06 μm or less, preferably 0.03 μm or less, so that when uniformly dispersed in the raw material, the entire PSZ ceramic is uniformly colored and high strength and toughness properties are obtained.

The ZrO raw material has an average particle diameter of 0.15 μm or less, preferably 0.06 μm or less, or may be a material that becomes ZrO□ powder upon calcination, such as zirconium hydroxide. This zirconium hydroxide (ZrO□ ・XH
20), the higher the calcination temperature, the more ZrO□
Since the primary particles of the powder become large, by changing the calcination temperature within the range of 9°O to 1050°C, Zr0z powder with an average primary particle diameter of 0.02 to 0.1 AIm can be obtained.

The stabilizers include Y2O3, MgO, CaO and CeO.
Known materials such as Z.

When Y2O is blended alone, it may be added at a content ratio of 2 to 7 mol% in the sintered body.

Further, when CaO and MgO are individually blended, they may be added at a content ratio of 8 to 11 mol% and 7 to 13 mol%, respectively, in the sintered body.

This stabilizer preferably has an average particle diameter of 2 μm or less, preferably 1 μm or less. Alternatively, a co-precipitated Zr0z powder to which a predetermined amount of stabilizer has been added may be used. If this powder is used, the stabilizer and Zr02 will be mixed in a more dense and uniformly distributed state, thereby reducing the crystallization of the sintered body. This is desirable in that the particle size is made uniform.

The colored zirconia ceramic of the present invention contains a ZrO□ metal oxide coloring component and a stabilizer as essential components, but the inclusion of components other than the above components is not excluded. For example, when a grinding medium such as a ball is used in a mixed powder frame of zirconia, a stabilizer, and a coloring component, the components constituting this grinding medium are inevitably contained during the mixing and grinding. For example, alumina (Ah(h) etc.)
It is allowed to be mixed in up to 20% by weight based on the entire ceramic.

The sintering conditions employed in the first firing may be an oxidizing atmosphere, a vacuum atmosphere, or a reducing atmosphere, and an oxidizing atmosphere is particularly preferred. With this oxidizing atmosphere, it is easy to set the firing conditions, and as a result, it is possible to achieve desired coloring without uneven coloring among the individual pieces.

Further, according to this first firing, either pressure sintering or non-pressure sintering may be used, and pressure sintering may include hot press, H
There are IP etc.

Thus, the colored ceramic molded body obtained by the first firing tends to have lower strength and toughness due to the colored components. However, since a metal oxide is used as a coloring component, it does not thermally decompose during firing, which prevents voids from occurring in the sintered body and enables uniform coloring. There is an advantage.

Further, the colored ceramic molded body obtained by this first firing contains Zr0z tetragonal crystals, and the sintering conditions are preferably set appropriately so that the content is as high as possible. The ZrO□rO□ crystal is ZrO
□If the content of about 80 mol% or more is contained in the middle 60 mol% or more, high strength and high toughness properties can be advantageously achieved by the next second firing (hereinafter referred to as the second firing). can do.

According to the second firing, a carbon-containing atmosphere is essential, which reduces the metal oxide in the colored PSZ ceramic molded body and causes ZrC to be contained in the sintered body, resulting in a change in the color tone of the base. can be blackened or darkened as desired. This firing generally ranges from 1100 to 1
It is preferable to carry out the reaction at a temperature of 650°C, especially 1300 to 1550°C.

For firing in such a reducing atmosphere, for example, colored PSz
The ceramic molded body is brought into contact with a carbon component such as a carbon blank and fired in a non-oxide atmosphere (this is usually called burying), or a carbon source is installed inside a +1 IP device, and the carbon component is heated. may be impregnated into ceramics, or these two firing methods may be combined.

According to this second firing, various firing methods can be adopted as long as the firing is performed in a carbon-containing atmosphere, but in particular, when the P method is performed, high toughness characteristics are maintained or improved. This is desirable in that it is possible.

According to such an old P method, the above-mentioned coloring P is applied to the IIP device.
There is a partition chamber in which the sz ceramic molded body is to be placed, and an inert gas (Ar, Nz) is introduced into this chamber, and at the same time it is pressurized and heated to a predetermined amount, thereby performing the old P firing. be exposed.

When placing the colored PSZ ceramic molded body in this partition chamber, a carbon container is prepared, the molded body is placed in this container, and if desired, this container is closed with a lid, etc., and then such a container is placed in the above-mentioned manner. It can be installed inside the bulkhead room.

Further, a carbon source that makes the molded body black or dark-colored may be placed inside the container together with the molded body.

When performing HIP firing, the pressure is 1000 to 200
Within the range of 0 atm (gauge pressure) and the temperature is 140
Setting the temperature within the range of 0 to 1600°C is advantageous in that carbon can be efficiently impregnated into the ceramic molded body.

According to the second firing, the colored zirconia ceramic molded body obtained by the first firing is impregnated with carbon and the metal oxide is reduced, thereby making it possible to color it as desired. When reducing the metal oxide, the degree of coloring can be changed as appropriate depending on the amount of reduction.
Depending on the type of metal oxide, firing conditions, etc., it can be partially or completely reduced.

Moreover, according to this second firing, a part of ZrO becomes Zr
When reduced to C and both ZrO□ and ZrC coexist within predetermined ranges, strength and toughness are enhanced.

That is, ZrC is 0.05% by weight based on the entire ceramic.
It is sufficient to form the ZrOz within the range of above and below 0.2% by weight; within this range, the desired blackening or darkening can be obtained, high strength and toughness properties are obtained, and the crystalline phase of Zr0z is desirable in that high strength and high toughness properties can be obtained when the firing conditions are set so that the tetragonal crystals in Zr0z account for about 60 mol % or more, preferably 80 mol % or more.

Furthermore, according to the second firing, there may be a small amount of free carbon in the ceramic molded body due to this carbon impregnation, but the amount remaining is an order of magnitude greater than when carbon is blended into the ceramic molded body. small.

Further, the surface of the colored PsZ ceramic molded body obtained by the second firing was coated with a diamond wheel.
When polished with diamond powder, diamond paste, etc., the crystal grain size of the molded product becomes uniform and small, and there are almost no voids, resulting in a mirror surface with deep luster.

In this way, even coloring can be achieved by the first firing, and desired coloring, as well as high strength and toughness properties can be obtained by the second firing.

〔Example〕

Next, examples of the present invention will be described.

(Example 1) 100 parts by weight of high-purity ZrO2 powder, 5.3 parts by weight of Y2O3 stabilizer, and Cr, Fe, and Ti as coloring components.
, Co, and Ni oxides were mixed so that the total amount was 2 parts by weight, and wet-pulverized using an alumina ball.
Then, it was dried. The raw material powder obtained by this is 1
The powder was passed through a 20-mesh comb, paraffin wax was added to the particle size-adjusted powder, and the powder was further passed through an 80-mesh comb. The powder mixture thus obtained was molded under a pressure of 1 t.
on/cm2 into a shape of 3.5 x 3.5 x 40 mm, and after removing the binder, fired in an oxidizing atmosphere at a temperature of 1.
When the first firing was performed at 450 degrees, a dark blue colored zirconia ceramic molded body was obtained.

Zr0z of the ceramic molded body thus obtained
The tetragonal crystal content is about 80 mol% in the total ZrO□,
When the strength and toughness were measured, each weighed 95Kg.
/cm" and 12.1 MN/m".

In addition, the strength was determined by the three-point bending test method of JIS-R-1601, and the toughness was determined by S, E, N, B (Single Edge).
This is the critical stress intensity factor value when ceramics break due to the growth of microcranks using the Notched Beam (Notched Beam) method.

Next, 111 was applied to the colored PSZ ceramic molded body.
The second firing was performed using two methods.

That is, l! The molded body was placed together with a carbon source (for example, carbon paper) in a carbon container for IP, the container was closed with a lid, and then this container was installed inside the old P device. Then, the firing temperature was set to 1475" and Ar gas was used as C1 pressure medium, and the pressure was set to 2000 Kg/cm2.
(gauge pressure), and the +11P treatment was performed for 1 hour.

The surface of the ceramic molded body thus obtained was rough compared to the state before HIP.

Therefore, the entire surface of this ceramic molded body was
When the molded product was ground and polished over a thickness of m, it had a greenish-blue base color with a pale black color and a glossy surface with few voids.The crystalline components of this molded product were also measured. However, ZrO□ is about 95% by weight,
ZrC is approximately 0.08% by weight, free carbon is approximately 0.01% by weight, and the coloring metal component is approximately 2% by weight in terms of its oxide, and this ZrQ is 90% by mole.
It was made of tetragonal crystals.

In addition, when the strength and toughness of this ceramic molded body were measured, they were each 125 Kg/cm2.14.1M
It was N1m3/Z.

(Example 2) In this example, (Example 1) the blending amount of the medium metal oxide was changed in several ways, and the other manufacturing conditions for the first firing and second firing were set to be the same as in (Example 1). As a result, ceramic molded bodies of samples Nos. 1 to 6 were obtained as shown in Table 1.

[Margin below]

As is clear from Table 1, samples 2 to 5 have a green-blue base color that has turned black, and the surface texture is void-free and glossy. It had high strength and high toughness properties.

However, for Sample No. 1, the amount of metal oxide coloring component blended was small, which made it impossible to achieve the required coloration as a base and caused color unevenness, and for Sample No. 6, the amount of metal oxide coloring component blended was small. Because the amount was too large, the strength and toughness were significantly reduced.

(Example 3) In this example, during the second firing in (Example 1), the firing temperature, pressure, ) IIP holding time, carbon source amount, etc. were changed,
By changing the ZrC content and setting the other manufacturing conditions the same as in Example 1, ceramic molded bodies of samples N17 to 14 were obtained as shown in Table 2.

[Margins below] As is clear from Table 2, samples 11h8 to 10 have a greenish-blue base with a light black tone, and a glossy surface with no voids. All samples had high strength and high toughness properties.

However, sample No. 7 had a significantly low ZrC content, and as a result, it was not possible to achieve a pale black color over the entire surface, and moreover, color unevenness occurred.

〔Effect of the invention〕

As described above, the colored zirconia ceramic of the present invention has high strength and high toughness characteristics, and can obtain a desired darkening color tone for molded bodies of small dimensions and shapes by using the metal compound coloring component and ZrC. be able to.

Further, according to the colored zirconia ceramic of the present invention, by polishing its surface, it becomes a mirror surface with a deep luster, and can be used for various decorative members. Examples include watch cases, dials, tie pins, shields, bracelets, rings, buttons, pendants, spike studs, etc.

Furthermore, the colored zirconia ceramics of the present invention have high strength and high toughness characteristics and can be colored to have a metallic tone, so that they can be used in various metal substitute members. For example, it can be used for daily necessities such as cutlery, various industrial structures, machine parts, etc.

Furthermore, according to the method for producing colored zirconia ceramics of the present invention, a colored member with high strength and high toughness characteristics can be obtained, and the coloring is uniform, thereby increasing the manufacturing yield and resulting in low cost and Colored zirconia ceramics that achieve high quality and high reliability can be provided.

Patent applicant (663) Kinju Anjo, representative of Kyocera Corporation

Claims (2)

[Claims] (1) Contains 0.1 to 10% by weight of coloring components, stabilizers, 0.05% by weight or more and less than 0.2% by weight of zirconium carbide in terms of metal oxide, and has a free carbon content of 0. A colored zirconia ceramic comprising .1% by weight or less of zirconia, and characterized in that the crystalline phase of the zirconia is a tetragonal crystal. (2) A molded body having a desired shape is formed from a raw material consisting of 0.1 to 10 parts by weight of a metal oxide, 90 to 99.9 parts by weight of zirconia, and a stabilizer, and the molded body is subjected to a first firing. is sintered and then colored as desired by a second firing in a carbon-containing atmosphere to produce a zirconia ceramic which contains at least 0.05% by weight and 0.2% by weight of the reduction product of the metal oxide. A method for producing a colored zirconia ceramic, characterized in that it contains less than 1% zirconium carbide, has a free element content of 0.1% by weight or less, and is composed of zirconia tetragonal crystals.