JPS6337060B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to materials for various decorative members including watch parts and pendants, and methods for manufacturing the same. Materials for decorative parts of this type need to have an elegant appearance over a long period of time, and for this reason, it is essential that they have good corrosion resistance and abrasion resistance. Properties such as high toughness are required. In recent years, cemented carbide-based materials have come to be widely used for this type of decorative material, but the drawbacks of cemented carbide are that it is too heavy, it is difficult to obtain a color tone close to jet black, and it has poor corrosion resistance. Materials with even greater wear resistance have become desirable. The present invention has been made in view of the above-mentioned current situation, and its gist is that at least one of the following components A and B is contained in an amount of 0.005 to 7.0% by weight, and the balance is 2 to 5% by weight.
A zirconia black material for decorative members, which is made of ZrO ₂ partially stabilized with mol% of Y ₂ O ₃ and has a beautiful glossy surface. A component: FeO, Fe ₃ O ₄ or FeOx (x<
1.5), CoOx (x<1), NiOx (x<1),
CrO or CrOx (x<1.5), TiOx (x<1.5)
At least one type of 2) component B; one consisting of Al ₂ O ₃ :TiOx (x<2):Y ₂ O ₃ in a weight ratio of 60:40:10, and as a manufacturing method for such a material, hot pressing is used. This manufacturing method employs a hot isostatic press (hereinafter referred to as HP) and a hot isostatic press (hereinafter referred to as HIP). Note that the above-mentioned "black color" includes not only so-called true black but also gray-black that is close to black, as will be described in detail later. The experiments that led to the development of the present invention and their results will be shown below. <Experiment 1> Purity 99.99 partially stabilized with 3 mol% Y ₂ O ₃
% (including ₃ components of Y ₂ O) is used as a raw material, and each oxide _of Fe, Co, Ni, Cr, and Ti, which is component A, is blended as shown in Table 1 below to prevent impurity contamination. The wet-pulverized slurry was dried and sized using a ball mill equipped with the following steps, and used as a raw material for sintering. When adopting the manufacturing process of press molding → preliminary sintering → HIP method, wax is added as necessary to produce grains with improved moldability and mold release properties, and molded at a pressure of 500 kg/cm ² or more. After that, it was passed through a wax removal process. On the other hand, when using the HP method, dry powder was filled into a graphite mold of a predetermined shape and HP was performed without adding wax. The preliminary sintering conditions for the above step were as follows: The sample was held at a temperature of 1450° C. for 1 hour in an atmosphere furnace with an inert gas (Ar) pressure of 1 atm. The HIP treatment conditions were an atmosphere of argon gas pressure of 1100 atm and a temperature of 1400° C. for 1 hour. The HP conditions were a pressure of 100 Kg/cm ² and a temperature of 1400° C., which were maintained for 1 hour. The sample for the characteristic investigation was a 5 x 5 x 25 (mm) specimen ground with a diamond grinding wheel, as shown in Tables 2 and 3.
The data shown in the table was obtained.

【table】

【table】

【table】

【table】

【table】

[Table] <Experiment 2> B was added to the same ZrO ₂ powder raw material used in Experiment 1.
The ingredients were mixed as shown in Table 4, and a raw material for sintering was prepared in the same manner as in Experiment 1. After dewaxing the molded body using the above sintering raw material under a pressure of 500Kg/cm2 ^{or more} , the relative density is 94.5%.
Table 4 also shows the results of investigating a sample obtained by preparing a pre-sintered body having the above and then densifying it in a HIP apparatus under conditions such that the relative density is 99.0% or more. The above pre-sintering was held in a vacuum furnace at 1400℃ for 1 hour, and the HIP conditions were argon gas pressure.
It was maintained at a temperature of 1320°C in an atmosphere of 1800 atm for 1 hour.

[Table] <Experiment 3> The same ZrO ₂ powder raw material used in Experiment 1 was mixed with colorant A and B components as shown in Table 5, and a raw material for sintering was created in the same manner as in Example 1. did. After molding the above raw material for sintering with a pressure of 500 kg/cm ² or more and dewaxing, pre-sintering is performed to a relative density of 94.5% or more, and then a HIP device is used to reduce the relative density to 99.0% or more. Table 6 also shows the results of investigating samples obtained by densification under the following conditions. The preliminary sintering conditions were held at a temperature of 1500° C. for 2 hours in an oxidizing atmosphere furnace. In addition, HIP conditions include inert gas (Ar) pressure.
It was held for 1 hour at 1500 atm and 1450°C.

【table】

【table】

[Table] Next, taking into account the above experimental results, we will discuss desirable components and characteristics as a material for decorative members, as well as manufacturing conditions for obtaining the desired material. The ZrO ₂ sintered material that is the base of the present invention has conventionally been stabilized or partially stabilized with CaO and MgO, but in recent years it has been stabilized with Y ₂ O ₃ or partially stabilized (hereinafter referred to as YSZ). ) has attracted great expectations due to its excellent strength, wear resistance, and other properties. However, this YSZ is generally produced by sintering a press-molded body in an atmospheric furnace, and the color tone of the material obtained in this way is white in the case of high-purity products, and changes from yellow to yellow as the purity deteriorates. The color changed to brown, and the strength tended to decrease as the purity deteriorated. With such white YSZ, there are subtle changes in color tone depending on the purity of the raw material powder, and there are often spots, etc., making it impossible to obtain a material with high commercial value. Therefore, as a result of various studies (mainly experimental results), the present inventors have used the HIP method in a non-oxidizing atmosphere.
We have discovered a coloring agent that can produce a beautiful grayish-black glossy surface by employing a HP sintering method. By the way, the ZrO ₂ used alone is difficult to sinter, and it is difficult to sinter it unless it is stabilized or partially stabilized with Y ₂ O ₃ , MgO, CaO, etc.
As mentioned above, YSZ using Y ₂ O ₃ is desirable, but if the amount of Y ₂ O ₃ is less than 2 mol%, the volume will increase due to the transformation of the zirconia crystal during sintering. If the change is too large, cracks are likely to occur.On the other hand, if more than 5 mol% of Y ₂ O ₃ is used, the crystal structure of the obtained sintered body will become coarser and stress will be applied to the sintered body. When this occurs, it becomes difficult for the crystal to transform from tetragonal to monoclinic, resulting in a decrease in the stress absorption effect, making it impossible to obtain a material with high strength and high toughness. Therefore, the YSZ used is 2 to 5 mol% Y ₂ O ₃
It is preferable to use It is not clear why the material of the present invention, which is obtained by containing the above-mentioned A and B components and sintering in a non-oxidizing atmosphere, gives a gray-black color tone to such YSZ. It is presumed that the colorant changes into a lower oxide in the atmosphere and reacts with the YSZ component to give a homogeneous color tone. From these points of view, component A as a raw material becomes a lower oxide in the final product and becomes a black material.
It is thought that it reacts with YSZ and provides excellent properties not only in terms of color tone but also in terms of strength. In addition, after sintering each of the oxides shown in Table 1 individually in a non-oxidizing atmosphere using hot pressing and hot isostatic pressing, analysis by X-ray diffraction revealed that the amount of oxygen in all oxides was Diffraction lines showing lower oxides, that is, lower oxides, and diffraction lines that could not be diffracted were confirmed. From this phenomenon, the various types of materials shown in Table 1 were sintered in an inert gas atmosphere and carbon was used at least in part in the sintering furnace and insulating material, so there was a trace amount of acid oxygen in the inert gas. The reaction between carbon and carbon produces CO, which reduces the raw material oxide, or the above-mentioned TiO ₂ , Fe ₂ O ₃ , NiO, Cr ₂ O ₃ ,
This is thought to be due to the fact that all of CoO and the like have the property of releasing some oxygen and dissociating in a high temperature range (where almost no O ₂ exists). Therefore, even without sintering in a particularly reducing atmosphere, component A as a raw material becomes a lower oxide. However, if sintered in a reducing gas atmosphere such as H ₂ or CO,
Furthermore, it is thought that further conversion to lower oxides is generated. Regarding B component, Al ₂ O ₃ ―TiO ₂ ―
TiO ₂ in the coloring raw material component of the present composition of Y ₂ O ₃ is also converted to a lower oxide TiOx during sintering in a non-oxidizing atmosphere.
(x<2), and it has been found that it provides excellent properties in terms of color tone, strength, and abrasion resistance. It is believed that the TiO ₂ in component B becomes a lower oxide TiOx (x<2) in the same manner as in the case of component A, and this was also confirmed by X-ray diffraction. By the way, as mentioned above for component B, the raw material composition was set at a ratio of Al ₂ O ₃ :TiO ₂ :Y ₂ O ₃ = 60:40:10 because a product with this ratio can be fired stably. This is because it is easy to use. That is, this B
When mixing component raw materials into partially stabilized ZrO ₂ , there is an appropriate amount within a certain range as described above, and by changing the mixing amount, Al ₂ O ₃ ,
Since the amounts of TiO ₂ and Y ₂ O ₃ can be changed, various experiments were conducted from the viewpoint that a composition that is easy to handle when blended into partially stabilized ZrO ₂ resulted in the following ratio of 60:40:10. When the product itself is fired, a material with no cracks and excellent relative density can be obtained, and when this B component is blended into the partially stabilized ZrO ₂ in the above range, the strength is also high. This is because it was confirmed that a material close to pure black can be obtained.
Furthermore, Y ₂ O ₃ in this B component is partially stabilized.
It is conceivable that ZrO ₂ becomes a solid solution in ZrO 2 when mixed and sintered with ZrO ₂ , but since ZrO ₂ is originally partially stabilized with Y ₂ O ₃ , Y ₂ in component B O ₃
Even if it dissolves into ZrO ₂ as a solid solution, the amount is small, and even if it does, there is no change in the proportion as the B component. Furthermore, it has been found that even when components A and B are used in combination, characteristics very suitable for the use of the present invention can be provided as shown in the examples. It should be noted that although it is possible to mix small amounts of each component of the colorant by a powder mixing method, the doping method is better for achieving a more homogeneous dispersion and blending. When TiO ₂ is used as the A component of the colorant of the present invention, a gray-black material with a reddish tinge may be obtained depending on the method of preparing the YSZ raw material, but in the above experiment, this was also classified as a gray-black material. did. A and B to make the material obtained in this way grayish black.
If the amount of at least one of the ingredients is less than 0.005% by weight, the color will approach grayish white, so even if there are slight spots, they will be more noticeable and have no value as a decorative item, and if the amount is less than 7% by weight. If the content exceeds 0.2%, the strength tends to decrease rapidly and there is a high possibility that the decorative item will be damaged if it is removed. Next, considering the manufacturing method, first of all, when sintering using the HP method, if the pressure during HP is less than 50 kg/cm ² , products with insufficient density will often be produced due to insufficient pressure. It is easy to produce defective products such as those where the wrapping surface becomes cloudy or has a pear-like appearance, or where there are spots. It goes without saying that the upper limit of the pressing force depends on the strength of the material such as graphite used for the hot press mold. Next, if the sintering temperature during HP is less than 1300°C, it is difficult to obtain a dense sintered body, and it is not economical as it requires holding for a long time to achieve dense sintering. On the other hand, if the sintering temperature exceeds 1,600°C, reaction adhesion with the mold will occur, resulting in cracks and defective products.In addition, it will not be possible to obtain a material with uniform and fine crystal grain size, resulting in decreased strength or a beautiful glossy surface. becomes difficult to obtain. Next, when using the HIP method, if the inert gas (usually argon gas) pressure is less than 1,000 atmospheres, products that are insufficiently dense due to insufficient pressurizing pressure will be produced more often, and the wrapping surface will become cloudy and pear-like. Defective products with wrinkles or spots are more likely to occur. Furthermore, if the temperature during HIP is less than 1300°C, the HIP effect, that is, densification, will be insufficient due to insufficient temperature. On the other hand, if the temperature exceeds 1600°C, the crystal grain size increases due to oversintering, making it impossible to obtain a product with high strength. In addition, if the relative density of the pre-sintered body to be subjected to HIP is less than 94.5%, there may be local density unevenness in the pre-sintered body, and even after HIP treatment, a product with a local lack of density may be obtained. at least 94.5% to obtain a homogeneous material.
It is preferable to have a relative density of . A black, homogeneous material can be obtained by selecting the composition structure and manufacturing conditions as described above, but from the viewpoint of the strength of the material, the density of the material obtained by the HIP method or HP method is The value divided by the theoretical density calculated from , that is, the relative density is 99%
If it is less than 1%, there will be micropores or spots equivalent to 1% or more, and it will not be possible to obtain a decorative item with a homogeneous and beautiful glossy surface, and in terms of strength, the shear value will be 0.1Kgfm/cm ² It is desirable that the relative density be 99% or higher, since it will not be possible to obtain a material with a relative density of 99% or higher. Furthermore, there is a possibility that decorative items may be dropped or hit by objects during handling, and it is natural that the lower the strength of the decorative item, the more likely it is to be damaged. The inventors believe that the breakage resistance in the above phenomenon is based on the bending strength (Kg/kg) commonly used for ceramic materials.
mm ² ) is more closely related to breakage resistance, and furthermore, the sharpy value is 0.1Kgfm/cm ²
It has been found that if it is less than that, there is a possibility of damage. This breakage resistance was a conclusion obtained as a result of a drop test, and the fall distance ranged from a height of 1 m, which is the height normally handled by humans, to a maximum of 2 m. The theoretical density values are 2 mol% Y ₂ O ₃ and 6
The theoretical density of YSZ is calculated from the monoclinic, tetragonal, and cubic lattice constants and composition ratios of the sintered body partially stabilized with Y ₂ O ₃ in the range of mole%, and the coloring component composition ratio is also taken into account. The theoretical density of the invention material was calculated. As mentioned above, the material of the present invention has high hardness and excellent abrasion resistance, so it is difficult to get scratches even after long-term use, and it has a uniform and beautiful appearance, which is the most important for decorative materials. It is excellent in that it exhibits a gray-black color. Also, when compared to, for example, TaC-based or WC-based cemented carbide, the transverse rupture strength and impact value of the material itself may be somewhat inferior, but compared to the high specific gravity of these cemented carbide, which is usually 13 to 14. As mentioned above, the specific gravity of the material of the present invention is approximately 5 to 6, which is less than half that of cemented carbide, and it is very light, so it is easy to use when used for watch parts and other decorative items, and it does not fall off during use. Even if the material itself is light, the damage it receives when falling is significantly smaller than that of cemented carbide, so it has the advantage of not breaking or breaking.
Therefore, the material of the present invention has wear resistance unique to ceramics,
It can be said to be an excellent material that has a homogeneous black color without impairing its corrosion resistance and has great practical strength as a decorative member.

Claims (1)

[Claims] 1. At least one of the following A component and B component
Y ₂ O ₃ of 0.005 to 7.0% by weight and the balance 2 to 5 mol%
A black zirconia material for decorative parts, which is made of partially stabilized ZrO ₂ and has a beautiful glossy surface. Component A: FeO, Fe ₃ O ₄ or FeOx (x<
1.5), CoOx (x<1), NiOx (x<1),
CrO or CrOx (x<1.5), TiOx (x<
At least one type of 2) B component: Al ₂ O ₃ : TiOx (x<2): Y ₂ O ₃ in a weight ratio of 60:40:10 2 A relative density of 99% or more and a sharpy impact The zirconia black material for decorative members according to claim 1, which has a value of 0.1 Kgfm/cm ² or more. 3 At least one of the following A component and B component
Y ₂ O ₃ of 0.005 to 7.0% by weight and the balance 2 to 5 mol%
A method for producing a black zirconia material for decorative members, characterized by sintering a homogeneous mixed powder with partially stabilized ZrO ₂ in a mold of a desired shape by hot pressing in a non-oxidizing atmosphere. A component: At least one kind of oxide of Fe, Co, Ni, Cr, and Ti B component: Al ₂ O ₃ :TiO ₂ :Y ₂ O ₃ in a weight ratio of 60:
4. The manufacturing method according to claim 3, wherein the hot pressing conditions are a pressing force of 50 Kg/cm ² or more and a temperature of 1300 to 1600°C. 5 At least one of the following A component and B component
Y ₂ O ₃ of 0.005 to 7.0% by weight and the balance 2 to 5 mol%
The uniform mixed powder with partially stabilized ZrO ₂ is molded into the desired shape, and then the molded body is
1. A method for producing a black zirconia decorative member material, which comprises preliminary sintering to 94.5% or more and then sintering by a hot isostatic press method in a non-oxidizing atmosphere. A component: At least one kind of oxide of Fe, Co, Ni, Cr, and Ti B component: Al ₂ O ₃ :TiO ₂ :Y ₂ O ₃ in a weight ratio of 60:
6 The hot isostatic press method has an inert gas pressure of 500 atmospheres or more and a temperature of 1300 to 1600.
6. The manufacturing method according to claim 5, wherein the temperature is .degree.