WO2012053640A1 - Clay-like composition for forming sintered body, powder for clay-like composition for forming sintered body, method for producing clay-like composition for forming sintered body, gold sintered body, and method for producing gold sintered body - Google Patents

Abstract

Provided is a clay-like composition (gold clay) for forming a sintered body, said clay-like composition being characterized by comprising: a powder component including metal powder containing gold and oxide powder containing copper; a binder; and water.

Description

Clay-like composition for forming sintered body, powder for clay-like composition for forming sintered body, method for producing clay-like composition for forming sintered body, gold sintered body, and method for producing gold sintered body

The present invention relates to a clay-like composition for forming a sintered body, a powder for a clay-like composition for forming a sintered body, a method for producing a clay-like composition for forming a sintered body, and a method for forming a sintered body. The present invention relates to a gold sintered body obtained from a clay-like composition and a method for producing the gold sintered body.
This application claims priority based on Japanese Patent Application No. 2010-237555 filed in Japan on October 22, 2010 and Japanese Patent Application No. 2011-226901 filed in Japan on October 14, 2011. , The contents of which are incorporated herein.

Conventionally, for example, gold jewelry and arts and crafts such as rings are generally manufactured by casting or forging a gold-containing material. In recent years, gold clay containing a gold powder (clay-like composition for forming a sintered body) is commercially available, and this gold clay is molded into an arbitrary shape and then fired to obtain gold having an arbitrary shape. Have been proposed (see, for example, Patent Documents 1 and 2).

The above-mentioned gold clay can be shaped freely in the same way as ordinary clay work, and after drying the shaped body obtained by shaping, it is fired using a heating furnace. It is possible to produce jewelry, arts and crafts, etc.
By the way, the gold clays described in Patent Documents 1 and 2 are generally obtained by kneading a pure gold powder with a binder, water, and a surfactant as necessary.

Japanese Patent Application Laid-Open No. 07-070602 JP 2000-026903 A

By the way, gold products are classified into 22K, 18K, and 14K grades according to the gold content. In addition, it is known that the color tone of gold products changes by adding silver or copper.
Thus, for example, Patent Document 2 provides gold clay in which Cu powder is mixed with gold powder.

However, the gold clay mixed with Cu powder has a problem that the color tone of the gold clay is easily deteriorated because Cu contained in the gold clay is easily altered. In detail, in gold clay mixed with Cu powder, when stored at room temperature and in an air atmosphere, discoloration has already been observed at the time when several days have passed since the gold clay was produced, and not only on the surface but also inside of it. The color will change over time.
As described above, since the discoloration of the gold clay is remarkable, the content of Cu cannot be increased greatly. For example, the gold clay for gold products having a content of 14K or 12K can be provided by containing Cu. There wasn't.

The present invention has been made in view of the above-described situation, and is a powder for a clay-like composition for forming a sintered body that is not easily discolored even in an air atmosphere, and a clay-like composition for forming a sintered body (gold Clay), a method for producing a clay-like composition for forming a sintered body, a gold sintered body, and a method for producing a gold sintered body.

When the present inventors diligently studied to solve the above-mentioned problem, the powder for gold clay (the clay-like composition for forming the sintered body) constituting the gold clay (the clay-like composition for forming the sintered body) was obtained. It has been found that discoloration of gold clay (clay-like composition for forming a sintered body) can be suppressed by constituting a powder containing a gold-containing metal powder and a copper-containing oxide powder.
This invention is made | formed based on the said knowledge, and has the structure shown below.

The clay-like composition for forming a sintered body according to the present invention is characterized by containing a powder component containing a gold-containing metal powder, a copper-containing oxide powder, a binder, and water.
Here, since the copper-containing oxide is chemically stable as compared with the metal Cu, there is little possibility that the copper-containing oxide is easily altered (the valence of the copper ion is changed) in an air atmosphere. For this reason, discoloration of this clay-like composition for forming a sintered body can be suppressed. Moreover, since it does not discolor even if it increases copper content, it becomes possible to provide the clay-like composition corresponding to the gold sintered compact with little content of Au.
Furthermore, by using oxygen in the copper-containing oxide, it becomes possible to burn and remove the binder in the clay-like composition for forming a sintered body, and to promote the firing of the clay-like composition. it can.

The powder component preferably contains a silver-containing metal powder. In this case, since the powder component contains gold-containing metal powder, silver-containing metal powder, and copper-containing oxide powder, by changing the content of each of these powders, gold sintering It becomes possible to adjust the color of the body. Moreover, it becomes possible to provide the clay-like composition which forms the gold | metal sintered compact with little content of Au by increasing content of Ag component and Cu component.
In the clay-like composition for forming the sintered body, the Fe content in the powder component is preferably 1000 ppm or less.
When the content of Fe in the powder component of the clay-like composition is 1000 ppm or less, the effect of improving the sinterability tends to be obtained.

Moreover, it is preferable that the said powder component contains CuO powder in 10 to 35 mass% with respect to the said whole powder component.
When the content of the CuO powder is 10% by mass or more, since the binder can be burned using the oxygen of CuO, it is not necessary to perform preliminary firing in the air atmosphere. Moreover, when content of CuO powder exceeds 35 mass%, there exists a possibility that the elongation of a sintered body may fall.
From the above, in the powder component, the content of CuO powder is preferably in the range of 10% by mass to 35% by mass with respect to the entire powder component.

Further, the powder component, is preferably contained in Cu 2 _O powder range of 45 wt% to 15 wt% based on the total the powder component.
When the content of the Cu ₂ O powder is 15% by mass or more, since the binder can be burned using the oxygen of Cu ₂ O, it is not necessary to perform preliminary firing in the air atmosphere. If the content of Cu 2 _O powder exceeds 45 wt%, the elongation of the fired product may be decreased.
From the above, in the powder component, the content of Cu ₂ O powder is preferably in the range of 15% by mass or more and 45% by mass or less with respect to the entire powder component.
Although gradually changed to Cu 2 _O is gradually CuO, not accompanying rapid discoloration as when additive metals Cu.

Moreover, it is preferable that content of metal Cu in the said powder component is 10 mass% or less with respect to the said whole powder component.
By making content of metal Cu in the said powder component into 10 mass% or less with respect to the said whole powder component, discoloration of the clay-like composition for sintered compact formation can be prevented reliably. Examples of metal Cu contained in the powder component include metal Cu powder, alloy powder of Au and Cu, alloy powder of Ag and Cu, and metal Cu contained in alloy powder of Au, Ag and Cu, and the like. Is mentioned.

Furthermore, it is preferable that the total content of the CuO powder and the Cu ₂ O powder in the powder component is 55% by mass or less based on the entire powder component.
When a large amount of oxides such as CuO and Cu ₂ O are contained in the powder component, it is difficult for the binder to be burned out and reduced by CO, and the sinterability is improved when the clay-like composition for forming a sintered body is fired. There is a risk of adverse effects. From the above, it is preferable that the total content of the CuO powder and the Cu ₂ O powder in the powder component is 55% by mass or less based on the entire powder component.

Moreover, it is preferable that the particle size of the said copper containing oxide powder is 1 micrometer or more and 25 micrometers or less.
In this case, it is possible to improve the mechanical strength and elongation of the gold sintered body obtained by firing the clay-like composition for forming the sintered body.

The clay-like composition may further contain at least one of fats and oils and surfactants as necessary.
Further, the clay-like composition for forming the sintered body is preferably composed of at least one of the binder, cellulose binder, polyvinyl binder, acrylic binder, wax binder, resin binder, starch, gelatin, and wheat flour. You may comprise by 1 type or the combination of 2 or more types. Of the above, it is most preferable to use a cellulose binder, particularly water-soluble cellulose.
The type of the surfactant is not particularly limited, and a normal surfactant (for example, polyethylene glycol or the like) can be used.
Examples of the fats and oils include organic acids (oleic acid, stearic acid, phthalic acid, palmitic acid, sepacic acid, acetylcitric acid, hydroxybenzoic acid, lauric acid, myristic acid, caproic acid, enanthic acid, butyric acid, capric acid). , Organic acid esters (organic acid esters having methyl, ethyl, propyl, butyl, octyl, hexyl, dimethyl, diethyl, isopropyl, and isobutyl groups), higher alcohols (octanol, nonanol, decanol) And polyhydric alcohols (glycerin, arabit, sorbitan), ethers (dioctyl ether, didecyl ether) and the like.

The powder for clay-like composition for forming a sintered body of the present invention is characterized by containing a gold-containing metal powder and a copper-containing oxide powder.
The powder for clay-like composition for forming the sintered body preferably contains a silver-containing metal powder.
Moreover, it is preferable that the powder for clay-like compositions for forming the sintered body contains CuO powder in the range of 10% by mass to 35% by mass with respect to the whole powder for clay-like composition.
Or it is preferable that the powder for clay-like compositions for forming the sintered body contains Cu ₂ O powder in the range of 15% by mass to 45% by mass with respect to the whole powder for clay-like composition.
Further, in the powder for clay-like composition for forming the sintered body, the content of metal Cu in the powder for clay-like composition is 10% by mass or less based on the whole powder for clay-like composition. preferable.
Moreover, the powder for clay-like composition for forming the sintered body has a total content of CuO and Cu ₂ O in the powder for clay-like composition with respect to the whole powder for clay-like composition. It is preferable that it is 55 mass% or less.
Furthermore, in the powder for clay-like composition for forming the sintered body, the copper-containing oxide powder preferably has a particle size of 1 μm or more and 25 μm or less.
According to the powder for a clay-like composition for forming a sintered body having the above-described configuration, it becomes possible to constitute the clay-like composition for forming a sintered body described above. Discoloration can be prevented.

The method for producing a clay-like composition for forming a sintered body according to the present invention is characterized by mixing a gold-containing metal powder, a copper-containing oxide powder, a binder, and water.
According to the method for producing a clay-like composition for forming a sintered body having this configuration, it becomes possible to produce a clay-like composition for forming a sintered body that has a copper-containing oxide powder and hardly discolors. .

The gold sintered body of the present invention is obtained by firing the above-mentioned clay-like composition for forming a sintered body.
According to the gold sintered body having this configuration, since the clay-like composition for forming a sintered body having the above-described configuration is fired, the gold-containing metal powder and the copper-containing oxide powder are included. By changing the mixing ratio of these powders, the quality (Au content) and color tone can be adjusted.

The method for producing a gold sintered body according to the present invention includes a step of obtaining a molded body by molding the above clay-like composition for forming a sintered body into an arbitrary shape, a step of drying the molded body, and a drying step. And a step of firing the molded body in a reducing atmosphere or a non-oxidizing atmosphere.

According to the method for producing a gold sintered body having the above configuration, the quality (Au content) and color tone of the gold sintered body are adjusted by changing the mixing ratio of the gold-containing metal powder and the copper-containing oxide powder. It becomes possible.
As described above, in the clay-like composition for forming a sintered body, when the CuO powder content is 10% by mass or more or the Cu ₂ O powder content is 15% by mass or more, CuO and By using the oxygen of Cu ₂ O, the binder contained in the clay-like composition for forming the sintered body can be burned and removed, so that the calcination step for removing the binder is omitted. be able to.

In the method for producing a gold sintered body, the firing step is performed in a reducing atmosphere or a non-oxidizing atmosphere at a firing temperature in the range of 720 ° C. or more and 1000 ° C. or less for 30 minutes to 180 minutes. It is preferable that it is the process of baking.
According to the method for producing a gold sintered body having this configuration, since the firing conditions of the molded body of the clay-like composition for forming the sintered body are limited as described above, the firing can be reliably performed. it can.

Moreover, in the manufacturing method of the said gold sintered compact, it is preferable to bake in the state which embedded the said molded object in activated carbon.
According to the method for producing a gold sintered body having this configuration, firing of the molded body can be promoted by reduction with activated carbon. In addition, sintering can be reliably performed with simple equipment.

According to the clay-like composition for forming a sintered body of the present invention, it is possible to suppress discoloration of the clay-like composition for forming a sintered body by the above-described configuration and action, and to obtain the sintered body by heating and firing after molding. The gold sintered body having a desired quality and color tone can be produced. According to the powder for a clay-like composition for forming a sintered body of the present invention, the clay-like composition for forming a sintered body using the powder for a clay-like composition for forming a sintered body due to the above-described configuration and action. By constituting the product, discoloration of the clay-like composition for forming a sintered body can be suppressed.
According to the method for producing a clay-like composition for forming a sintered body of the present invention, the above-mentioned clay-like composition for forming a sintered body can be reliably produced.
According to the gold sintered body of the present invention and the method for producing the gold sintered body of the present invention, by changing the mixing ratio of the gold-containing metal powder and the copper-containing oxide powder, the quality of the gold sintered body ( Au content) and color tone can be adjusted.

It is the schematic which shows the manufacturing method of the clay-like composition for sintered compact formation which concerns on one Embodiment of this invention. It is the schematic of 1 process which shows the manufacturing method of the gold sintered compact using the clay-like composition for sintered compact formation which concerns on one Embodiment of this invention. It is the schematic of 1 process which shows the manufacturing method of the gold sintered compact using the clay-like composition for sintered compact formation which concerns on one Embodiment of this invention. It is the schematic of 1 process which shows the manufacturing method of the gold sintered compact using the clay-like composition for sintered compact formation which concerns on one Embodiment of this invention. It is the schematic of 1 process which shows the manufacturing method of the gold sintered compact using the clay-like composition for sintered compact formation which concerns on one Embodiment of this invention.

Below, a clay-like composition for forming a sintered body according to the present invention, a powder for clay-like composition for forming a sintered body, a method for producing a clay-like composition for forming a sintered body, a gold sintered body, and An embodiment of a method for producing a gold sintered body will be described with reference to the drawings as appropriate.
In the present embodiment, the clay-like composition for forming a sintered body is referred to as gold clay, and the powder for the clay-like composition for forming a sintered body is referred to as a gold clay powder.

(Gold clay powder)
The gold clay powder of this embodiment includes a gold-containing metal powder containing gold, a silver-containing metal powder containing silver, and a copper-containing oxide powder containing copper.
By using such a powder for gold clay and adding the additives described later to knead to constitute the gold clay, the effect of suppressing the discoloration of the gold clay can be obtained.

In the powder for gold clay according to the present embodiment, Au powder, Au-Cu alloy powder, Au-Ag alloy powder, Au-Ag-Cu alloy powder or the like can be applied as the gold-containing metal powder. It is.
As the silver-containing metal powder, Ag powder, Ag—Au alloy powder, Ag—Cu alloy powder, Ag—Au—Cu alloy powder, or the like can be applied.
Furthermore, it is possible to apply the CuO powder and Cu 2 _O powder such as copper-containing oxide powder.
Moreover, metals other than Ag, Au, and Cu may be contained in the powder for gold clay.
These powders are put in a kneader and mixed and pulverized to uniformly mix the powders and adjust the particles of the powders to a predetermined particle size.

Furthermore, Fe peels from the inner wall surface of the pulverizer used in the step of pulverizing the powder for gold clay so as to have a predetermined particle size and the step of kneading each powder or the stainless steel container of the kneading device, or in the powder It is mixed in the clay-like composition.
As a result of investigations by the present inventors, it has been found that Fe is a cause of lowering the sinterability of the clay-like composition because Fe hardly diffuses into Au, Ag, and Cu.
Moreover, in operations such as a normal smelting process, Fe is hardly mixed as an impurity into Au, Ag, and Cu. Therefore, it is more preferable that Fe mixed in the powder for gold clay in the pulverization step and the kneading step can be reduced.
In particular, the content of Fe in the powder component of the clay-like composition is preferably 1000 ppm or less, and more preferably 200 ppm or less. By suppressing the Fe content in the powder component of the clay-like composition or in the powder for the clay-like composition to 1000 ppm or less, a sinterability is improved and a gold sintered body having high mechanical strength is produced. Can do.
In the present embodiment, it is preferable to coat CrN on the inner wall of the stainless steel container of the pulverizer or kneader. Since the CrN coating has excellent wear resistance and lubricity, it is possible to prevent Fe from being mixed into the gold clay powder.

When CuO powder is used as the copper-containing oxide powder, the gold clay powder preferably contains CuO powder in the range of 10% by mass to 35% by mass.
Also, when using Cu 2 _O powder as copper-containing oxide powder preferably contains at Cu 2 _O powder below 45 wt% to 15 wt% range to the gold clay for powder.
Furthermore, it is preferable that the total of the content of the CuO powder and the content of the Cu ₂ O powder in the gold clay powder is 55% by mass or less.

Here, the color tone of the sintered gold body after sintering can be adjusted by adding Ag and Cu to the gold clay. It is also possible to produce gold sinters of various grades such as 22K to 12K by adjusting the Au content.
Therefore, it is preferable to configure the gold clay by adjusting the mixing ratio of the gold-containing metal powder, the silver-containing metal powder, and the copper-containing oxide powder according to the color tone and quality of the gold sintered body.

Here, in this embodiment, Au powder is used as the gold-containing metal powder, Ag powder is used as the silver-containing metal powder, and CuO powder is used as the copper-containing oxide powder.
In the present embodiment, the particle sizes of Au powder, Ag powder and CuO powder are not particularly limited, but formability when gold clay is obtained by adding and kneading a binder as an additive. In consideration of various characteristics such as the above, it is preferable to set the particle size within the following range.

If the average particle diameter of the Au powder, Ag powder and CuO powder exceeds 25 μm, the sinterability of the powder is lowered and the firing time is prolonged. Moreover, there exists a possibility that the color tone of a gold sintered compact may deteriorate. From the above, it is preferable that the average particle size of the Au powder, Ag powder and CuO powder is 25 μm or less.
In addition, the lower limit of the average particle diameter of the Au powder, Ag powder and CuO powder is not particularly defined, but setting the average particle diameter of the Au powder, Ag powder and CuO powder to 1 μm or less increases the cost for industrial production. There is also a fear, and it is preferable to set the lower limit in consideration of the limit of the apparatus. In order to achieve the above-described effects, the average particle size of Au powder, Ag powder and CuO powder is more preferably in the range of 1 μm to 20 μm, and more preferably in the range of 3 μm to 10 μm. More preferably.

Furthermore, in this embodiment, the gold clay molded body is fired by limiting the average particle size of the Au powder, Ag powder and CuO powder constituting the gold clay powder to a predetermined particle size or less as described above. Since the sinterability at that time is enhanced, it becomes possible to lower the processing temperature in the firing described later.
In addition, as a method for measuring the average particle diameter of the powder as described above, for example, a known microtrack method can be used. In this embodiment, d50 (median diameter) is the average particle diameter.

(Gold clay)
Next, the gold clay of this embodiment will be described.
The gold clay according to the present embodiment includes the powder for gold clay having the above-described configuration, a binder (an organic binder in the present embodiment), and water.
For example, the gold clay according to the present embodiment contains the powder for gold clay having the above configuration in the range of 70% by mass to 95% by mass, and further contains 5% by mass to 30% of a binder agent containing an organic binder and water. It contains in the range below mass%. Here, in addition to the organic binder and water, a surfactant and fats and oils may be added to the binder as necessary.
Since this gold clay is a gold clay containing chemically stable CuO powder, Au powder, and Ag powder, discoloration is suppressed in an air atmosphere.

It does not specifically limit as an organic binder used for the gold clay which concerns on this embodiment, The organic substance which can connect the powder for gold clay and can be used as a clay-like composition can be utilized. For example, it is preferable to use at least one or a combination of two or more of cellulose binder, polyvinyl binder, acrylic binder, wax binder, resin binder, starch, gelatin, and wheat flour. Of the above, it is most preferable to use a cellulose-based binder, particularly water-soluble cellulose.
The said surfactant is not specifically limited, A normal surfactant (for example, polyethyleneglycol etc.) can be used.

Also, the type of fats and oils is not particularly limited. Enanthic acid, butyric acid, capric acid), organic acid esters (organic acid esters having methyl, ethyl, propyl, butyl, octyl, hexyl, dimethyl, diethyl, isopropyl, and isobutyl groups), higher grades Examples include alcohols (octanol, nonanol, decanol), polyhydric alcohols (glycerin, arabit, sorbitan), ethers (dioctyl ether, didecyl ether) and the like.

Hereinafter, an example of a method for producing the gold clay according to the present embodiment described above will be described with reference to the schematic diagram shown in FIG.
The manufacturing method of the gold clay 5 according to the present embodiment is such that the powder 1 for gold clay is 70% by mass to 95% by mass, and the binder agent 2 containing an organic binder and water is 5% by mass to 30% by mass. This is a kneading method.

As shown in FIG. 1, in the method for producing gold clay 5 described in the present embodiment, first, each of Au powder 1A, Ag powder 1B, and CuO powder 1C is introduced into a kneading apparatus 50 in a prescribed amount. At this time, for example, 72.7% by mass of Au powder 1A (average particle size 5 μm: microtrack method; atomized powder) and 12.1% by mass of Ag powder 1B (average particle size 5 μm: microtrack method; atomized powder) , CuO powder 1C (average particle size 5 μm: Microtrac method; reagent manufactured by Kishida Chemical Co., Ltd., purity 97% or more) is introduced as 15.2% by mass.
And the powder 1 for gold clay is obtained by mixing each said material powder within the kneading apparatus 50. FIG.

Next, as shown in FIG. 1, the binder agent 2 is added to the gold clay powder 1 in the kneading apparatus 50. At this time, for example, the addition amount of the binder agent 2 can be set to about {total weight of the powder 1 for silver clay: binder agent 2 = 9: 1}.
Here, the binder agent 2 is an organic binder mixed in a blend of 11 mass% to 17 mass%, fats and oils 5 mass% or less, surfactant 2 mass% or less, and the balance water. .

In the kneading apparatus 50, the gold clay 5 is obtained by mixing and kneading the powder 1 for gold clay and the binder agent 2.
In the present embodiment, it is preferable to coat the inner surface of the stainless steel kneading container of the kneading apparatus 50 with CrN as described above. Since CrN is excellent in wear resistance and lubricity, it is possible to prevent Fe in stainless steel from dropping off from the surface of the kneading container and mixing into the material powder in the kneading step. As a result, the content of Fe in the powder component of the clay-like composition can be set to 1000 ppm or less, which is a sufficiently small amount as a noble metal clay.

(Sintered gold)
The gold sintered body according to the present embodiment is obtained by shaping and molding the gold clay 5 having the above-described configuration into an arbitrary shape and then firing it under the conditions described below.

Hereinafter, an example of a method for manufacturing the gold sintered body according to the present embodiment as described above will be described with reference to the schematic views of FIGS. 2A to 2D.
In the method for manufacturing the gold sintered body 10 according to the present embodiment, the molded body 51 is obtained by molding the gold clay 5 having the above configuration into an arbitrary shape. Next, the molded body 51 is dried, for example, at a temperature of room temperature to 150 ° C. for 30 minutes to 24 hours, and then the molded body 51 is heated at a temperature of 720 to 1000 ° C. in a reducing atmosphere or non-oxidizing atmosphere. The gold sintered body 10 is obtained by firing for 30 to 180 minutes. Here, as the method for performing the firing, for example, a method in which the molded body 51 is embedded in activated carbon and then the firing is performed at a temperature of 720 to 1000 ° C. for a time of 30 to 180 minutes is adopted. it can.

First, as shown in FIG. 2A, the gold clay 5 is shaped and molded into an arbitrary shape by a conventionally known method such as mechanical processing by a stamper, press molding, extrusion molding, or manual processing by an operator. Thus, the formed body 51 is obtained.
Next, as shown in FIG. 2B, the molded body 51 is put into an electric furnace 80 and dried to remove moisture and the like.
The drying temperature at this time is preferably, for example, room temperature or a temperature in the range of about 80 ° C. to 150 ° C. from the viewpoint of effective drying treatment. From the same point of view, the drying time is, for example, 30 to 720 minutes, more preferably 30 to 90 minutes. For example, the drying temperature is about 100 ° C. and the drying time is 60 minutes. A drying process can be performed on the conditions made into the grade.

Next, as shown in FIG. 2C, the molded body 51 is fired to obtain a gold sintered body 10. At this time, by using the oxygen of CuO contained in the powder for gold clay, the organic binder contained in the gold clay is burned, and it becomes possible to remove the organic binder.
Here, “utilizing oxygen of CuO” means that CuO is thermally decomposed during firing to release oxygen and contribute to the combustion of the organic binder.
Moreover, in this embodiment, the method of manufacturing the gold sintered compact 10 can be employ | adopted by baking with respect to the molded object 51 by using an apparatus like the example of illustration.

At this time, first, the molded body 51 is embedded in activated carbon 61 filled in a ceramic firing container 60. At this time, in order to completely embed the molded body 51 and to prevent the molded body 51 from being exposed to the outside when the activated carbon burns, the distance from the surface of the activated carbon 61 in the firing container 60 to the molded body 51 is set. It is preferable to secure 10 mm or more.
Then, the firing container 60 in which the molded body 51 is embedded in the activated carbon 61 is put into the electric furnace 80, and as described above, at a temperature in the range of 720 to 1000 ° C. for a time of 30 to 180 minutes. Firing is performed by heating.

Then, for example, as shown in FIG. 2D, the gold sintered body 10 obtained by firing can be subjected to post-processing such as surface polishing and decoration treatment as necessary to obtain a product.

In the example shown in FIGS. 2A to 2D, for convenience of illustration and description, the molded body 51 and the gold sintered body 10 obtained by molding the gold clay 5 are formed in a substantially block shape. Needless to say, various shapes can be obtained.
Moreover, in this embodiment, although the example using an electric furnace is demonstrated in each process of a drying process and baking, it is not limited to this, For example, stable heating condition management, such as a gas heating apparatus If it is possible, it can be adopted without any limitation.

As described above, according to the gold clay 5 according to the present embodiment, since it contains chemically stable CuO, CuO does not easily change in the atmosphere, and the gold clay 5 is discolored. Can be suppressed. Moreover, it becomes possible by adjusting the content of Ag powder and CuO powder to adjust the color tone and quality of the gold fired body 10.
Furthermore, since the powder 1 for gold clay contains CuO powder in the range of 10% by mass or more and 35% by mass or less, it becomes possible to burn and remove the binder using oxygen of this CuO powder. . Therefore, the temporary baking process in an air atmosphere can be omitted.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical idea of the invention.
For example, although it demonstrated as a powder for gold clay containing Au powder, Ag powder, and CuO powder, it is not limited to this. Au alloy powder may be used as the gold-containing metal powder. Ag alloy powder may be used as the silver-containing metal powder. Cu ₂ O powder may be used as the copper oxide-containing powder, or both CuO powder and Cu ₂ O powder may be contained. However, the content of metal Cu in the powder for gold clay is preferably 10% by mass or less.

Moreover, although it explained as gold powder for gold clay containing Au powder, Ag powder and CuO powder, and gold clay was produced by adding a binder agent containing binder and water to this, it is limited to this. The gold clay may be produced by mixing the gold-containing clay containing gold and the copper oxide-containing clay containing copper oxide. Furthermore, you may produce gold clay by adding the powder of copper oxide with respect to commercially available gold clay, and adding a binder and water further.

Hereinafter, examples will be shown, powder for clay-like composition for forming a sintered body of the present invention, clay-like composition for forming a sintered body, a method for producing a clay-like composition for forming a sintered body, gold Although the manufacturing method of a sintered compact and a gold sintered compact is demonstrated in more detail, this invention is not limited to this Example.

(Gold clay)
(Example of the present invention)
First, a clay-like composition powder for forming a sintered body (hereinafter referred to as a gold clay powder) was prepared by the following procedure. In producing the powder for gold clay, Au powder (average particle size 5 μm: Microtrack method; atomized powder), Ag powder (average particle size 5 μm: Microtrack method; atomized powder), and CuO powder (average particle size 5 μm) : Microtrac method; reagent / purity 97% or more manufactured by Kishida Chemical Co., Ltd.) and Cu ₂ O powder (average particle size 5 μm: Microtrack method; reagent / purity 97% or more manufactured by Kishida Chemical Co., Ltd.), metal Cu powder ( An average particle size of 20 μm: Microclay method; manufactured by Fukuda Metal Foil Powder Industry Co., Ltd., purity 99% or more) is mixed by a kneading apparatus as shown in FIG. A powder was obtained. At this time, the stainless steel kneading container of the kneading apparatus used was one whose inner surface was coated with CrN.

Next, with the gold clay powder obtained in the above procedure left in the kneading apparatus, an organic binder, water, surfactant and oil are mixed to form a binder agent and then kneaded. A clay-like composition for forming a sintered body (hereinafter referred to as gold clay) was prepared.
Here, the binder agent was formulated such that 15% by mass of methyl cellulose as an organic binder, 3% by mass of olive oil, which is a kind of organic acid as an oil and fat, 1% by mass of polyethylene glycol as a surfactant, and the balance being water.
And it knead | mixed as 85 mass% of powders for gold clay, and 15 mass% of the above-mentioned binder agents, and it was set as gold clay.

(Comparative example)
In the comparative example, Au powder, Ag powder, and Cu powder were used as the powder for gold clay, and gold clay was produced in the same manner as the above-described example of the present invention.

(Component analysis)
Analysis was performed on the contents of elements of Au, Ag, and Cu contained in the gold clays of the present invention examples and comparative examples.
First, gold clay was washed with hot water at 90 ° C. or higher to remove the organic binder, surfactant and oil and fat, and then a predetermined amount (about 10 g) of a sample necessary for quantitative analysis was collected. Next, this analysis sample was subjected to quantitative analysis of Au, Ag, and Cu by ICP analysis. Also, the gold quality (K) was determined. The results are shown in Tables 1 and 2.

(discoloration)
Further, the discoloration of the gold clays of the inventive examples and the comparative examples was evaluated as follows.
A predetermined amount (10 g) of gold clay was collected, sandwiched between plate materials wrapped with a transparent polyethylene film, and crushed to a thickness of 1 mm. Then, it was stored at room temperature in an air atmosphere, and the presence or absence of discoloration was visually observed and evaluated. The evaluation results are shown in Tables 1 and 2.

In the comparative example using metal Cu as the copper component, discoloration was observed after 3 days.
On the other hand, in Example 1-9 of the present invention using CuO powder as the copper-containing oxide powder, it was possible to produce gold clay having a grade from 22K to 12K. Even after the above, no discoloration was observed. In addition, in Example 10-14 of the present invention using Cu ₂ O powder as the copper-containing oxide powder, it was possible to produce gold clay of grades from 18K to 12K. After the lapse of time, no discoloration was observed, and after 20 days, discoloration was observed.
Also, in inventive examples 15-19 and 21-23 containing 10% by mass or less of metallic Cu, no discoloration was observed after 2 weeks, and discoloration was observed after 20 days.
On the other hand, in Inventive Example 20 containing 15% by mass of metal Cu, discoloration was observed after one week although discoloration was suppressed as compared with the comparative example. From this result, in order to suppress the discoloration of the gold clay with certainty, it was confirmed that the content of the metal Cu is preferably 10% by mass or less.

(Gold fired body)
Next, the gold clays of Invention Examples 1-14, 18, 21 and Comparative Example were fired, and the obtained gold fired bodies were evaluated.

(Example of the present invention)
In an example of the present invention, by molding the gold clay obtained by the above procedure, a wire-shaped molded body having a diameter of about 1.2 mm and a length of about 50 mm (before firing), and a length of about 30 mm, A prismatic shaped body having dimensions of about 3 mm in width and about 3 mm in thickness (before firing) was produced.
Next, as shown in FIG. 2B, the wire-shaped molded body and the prismatic molded body 51 are put into an electric furnace (Orton: evenheat kiln inc.) 80 for each invention example at the same time, and the drying temperature is set to 100 ° C. And the moisture etc. which were contained in each above-mentioned fabrication object 51 were removed by performing drying processing on the conditions which made drying time 60 minutes.
In FIG. 2B, only one prismatic molded body is shown as the molded body 51, and the wire-shaped molded body is not shown.

Here, the temporary baking step was performed in an air atmosphere using an electric furnace 80. In addition, as shown in Tables 3 and 4, the preliminary firing step was partially omitted.

Next, a gold sintered body was produced by simultaneously firing each molded body 51 for each invention example.
Specifically, as shown in FIG. 2C, a ceramic firing container 60 filled with activated carbon 61 was prepared, and each molded body 51 was embedded in the activated carbon 61. At this time, the distance from the surface of the activated carbon 61 to each compact 51 was about 10 mm.
Then, the firing container 60 in which each molded body 51 was embedded in the activated carbon 61 was put into an electric furnace 80, and main firing was performed under the conditions described in Tables 3 and 4. Thereby, wire-shaped and prismatic gold sintered bodies 10 were produced.

(Comparative example)
In the comparative example, a wire-shaped molded body and a prismatic molded body having a length of about 30 mm, a width of about 3 mm, and a thickness of about 3 mm were produced in the same manner as the present invention.
Then, except for the conditions shown in the table, drying and firing (temporary firing, main firing) were carried out in the same procedure as in the present invention example, and wire-shaped and prismatic gold sintered bodies 10 were produced.

(Evaluation methods)
About the produced gold sintered compact, bending strength, tensile strength, density, surface hardness, and elongation were measured by the following test methods. The tensile strength and elongation were measured using a wire-shaped sintered body, and the bending strength, density, and surface hardness were measured using a prismatic sintered body.

The bending strength was determined by measuring a stress curve using an autograph AG-X manufactured by Shimadzu Corporation at an indentation speed of 0.5 mm / min and measuring the maximum point stress in the elastic region.
In addition, the tensile strength was obtained by measuring the stress curve at the moment when the test piece was broken using the autograph AG-X manufactured by Shimadzu Corporation and measuring the stress curve at a tensile speed of 5 mm / min.

Further, the surface hardness was determined by measuring the Vickers hardness after polishing the surface of the test piece and using a red microhardness meter under the conditions of a load of 100 g and a load holding time of 10 seconds.
Further, the elongation was obtained by measuring the stress curve at the moment when the test piece broke by measuring a stress curve at 5 mm / min with an autograph AG-X manufactured by Shimadzu Corporation.

Tables 3 and 4 show a list of manufacturing conditions and evaluation results of gold fired bodies obtained using the clays of Invention Examples 1-14, 18, 21 and Comparative Example.

(Evaluation results)
In the present invention example, it was confirmed that a gold sintered body can be obtained by carrying out the main calcination by reducing the activated carbon with a holding time of 1 hour.
Inventive Example 4 and Comparative Example have the same metal components as shown in Tables 1 and 2, but in Inventive Example 4, although the pre-baking step was omitted, the strength and surface hardness were reduced. Both the properties of elongation and elongation were good.

Here, when the present invention example 2 and the present invention example 8 in which the content of the CuO powder is 4.5% by mass are compared, the present invention example 8 in which the pre-baking step is omitted has only a strength that can be broken by hand, The mechanical properties could not be evaluated. On the other hand, as in Example 2 of the present invention, it was possible to obtain a fired gold body having sufficient strength by carrying out the temporary firing step.
On the other hand, Examples 3-7 and 9 of the present invention containing 10% by mass or more of CuO powder have sufficient strength even if the preliminary firing step is omitted. Therefore, in order to omit the temporary baking step, the content of the CuO powder is preferably 10% by mass or more.

Similarly, when the present invention example 10 and the present invention example 13 in which the content of the Cu ₂ O powder is 13.9% by mass are compared, the present invention example 13 in which the pre-baking step is omitted is only strong enough to be broken by hand. The mechanical properties could not be evaluated. On the other hand, as in Example 10 of the present invention, it was possible to obtain a fired gold body having sufficient strength by carrying out the temporary firing step.
In contrast, Cu for the present invention examples 11, 12 and 14 is _{the 2} O powder containing more than 15 wt%, sufficient strength be omitted calcination step is obtained. Therefore, in order to omit the temporary firing step, the content of the Cu ₂ O powder is preferably 15% by mass or more.

Further, in Example 9 of the present invention in which the content of CuO powder was 38.5% by mass and Example 14 of the present invention in which the content of Cu ₂ O powder was 53% by mass, the mechanical properties were slightly deteriorated. That is confirmed. From this result, when considering the mechanical characteristics of the gold sintered body, it is preferable that the content of the CuO powder is 35% by mass or less and the content of the Cu ₂ O powder is 45% by mass or less.

A gold clay was produced in the same manner as in Invention Example 4 except that a small amount of Fe powder was added to the powder for gold clay, and a gold clay of Invention Example 24 was obtained.
A gold clay was produced in the same manner as in Invention Example 4 except that Fe powder exceeding 1000 ppm was added to the powder for gold clay, and a gold clay of Invention Example 25 was obtained.
The gold clays of Invention Examples 4, 24, and 25 were subjected to quantitative analysis of Fe in the powder for gold clay by ICP analysis in the same manner as the component analysis described above. Moreover, the wire-like sintered compact was produced by the method similar to the above, and the tensile strength and elongation were measured. The results are shown in Table 5.

In Invention Example 24 and Invention Example 4 in which the content of Fe in the gold clay powder was 1000 ppm or less, favorable results were obtained in both tensile strength and elongation. On the other hand, in Invention Example 25 in which the Fe content in the powder for gold clay exceeds 1000 ppm, the elongation is remarkably reduced to 5% or less as compared with Invention Example 4 in which the Fe content is very small. In Inventive Example 25, it was confirmed that the tensile strength also decreased to 2/3 or less of Inventive Example 4, but the tensile strength that could withstand practical use was maintained.

From the results of the evaluation tests described above, the gold clay using the gold clay powder of the present embodiment can suppress discoloration and obtain a gold sintered body excellent in mechanical strength and elongation. It is clear that

1 Powder for gold clay (powder for clay-like composition for forming sintered body)
1A Au powder 1B Ag powder 1C CuO powder 5 Gold clay (clay-like composition for forming a sintered body)
51 Molded body 10 Gold sintered body

Claims (23)

1. A clay-like composition for forming a sintered body comprising a powder component containing a gold-containing metal powder, a copper-containing oxide powder, a binder, and water.
2. The clay-like composition for forming a sintered body according to claim 1, wherein the powder component contains a silver-containing metal powder.
3. The clay-like composition for forming a sintered body according to claim 1 or 2, wherein the content of Fe in the powder component is 1000 ppm or less.
4. The said powder component contains CuO powder as said copper-containing oxide powder in the range of 10 mass% or more and 35 mass% or less with respect to the said whole powder component. The clay-like composition for forming a sintered body as described.
5. Said powder component is any one of the copper-containing oxide powder as Cu 2 claims an _O powder is contained in an amount of less than 45 wt% to 15 wt% based on the total the powder component 1 to claim 4 The clay-like composition for forming a sintered body according to the item.
6. The clay-like composition for forming a sintered body according to any one of claims 1 to 5, wherein the content of metal Cu in the powder component is 10% by mass or less based on the entire powder component. object.
7. The total content of the CuO powder and the Cu ₂ O powder in the powder component is 55% by mass or less based on the entire powder component. The clay-like composition for forming a sintered body as described.
8. The clay-like composition for forming a sintered body according to any one of claims 1 to 7, wherein a particle diameter of the copper-containing oxide powder is 1 µm or more and 25 µm or less.
9. Furthermore, the clay-like composition for sintered compact formation as described in any one of Claim 1 thru | or 8 containing at least one among fats and oils and surfactant.
10. The binder is composed of at least one or a combination of two or more of a cellulose binder, a polyvinyl binder, an acrylic binder, a wax binder, a resin binder, starch, gelatin, and wheat flour. The clay-like composition for forming a sintered body according to any one of claims 9 to 9.
11. A powder for a clay-like composition for forming a sintered body comprising a gold-containing metal powder and a copper-containing oxide powder.
12. The powder for a clay-like composition for forming a sintered body according to claim 11, containing a silver-containing metal powder.
13. The powder for clay-like composition for forming a sintered body according to claim 11 or 12, wherein Fe content in the powder for clay-like composition is 1000 ppm or less.
14. The clay-like material for forming a sintered body according to any one of claims 11 to 13, comprising CuO powder in a range of 10% by mass to 35% by mass with respect to the whole powder for clay-like composition. Composition powder.
15. For the sintered body formed according to any one of claims 11 to 14 containing at Cu 2 _O powder below 45 wt% to 15 wt% range with respect to the total powder for the clay-like composition Powder for clay-like composition.
16. The firing according to any one of claims 11 to 15, wherein a content of metal Cu in the clay-like composition powder is 10 mass% or less with respect to the entire clay-like composition powder. Powder for clay-like composition for forming a knot.
17. The content of CuO of the clay-like composition for powder and Cu 2 _O total content of claims 11 to 16 is 55 mass% or less with respect to the total powder for the clay-like composition of The powder for clay-like compositions for forming a sintered body according to any one of the above.
18. The powder for clay-like composition for forming a sintered body according to any one of claims 11 to 17, wherein a particle diameter of the copper-containing oxide powder is 1 µm or more and 25 µm or less.
19. A method for producing a clay-like composition for forming a sintered body, comprising mixing a gold-containing metal powder, a copper-containing oxide powder, a binder, and water.
20. A gold sintered body obtained by firing the clay-like composition for forming a sintered body according to any one of claims 1 to 10.
21. A step of obtaining a molded body by molding the clay-like composition for forming a sintered body according to any one of claims 1 to 10 into an arbitrary shape;
    Drying the molded body,
    A method for producing a gold sintered body, comprising a step of firing a dried molded body in a reducing atmosphere or a non-oxidizing atmosphere.
22. The said baking process is a process of baking a molded object in the time of 30 minutes or more and 180 minutes or less at the baking temperature of the range of 720 degreeC or more and 1000 degrees C or less in a reducing atmosphere or a non-oxidizing atmosphere. A method for producing a gold sintered body.
23. The method for producing a gold sintered body according to claim 21 or 22, wherein the firing step is performed in a state where the molded body is embedded in activated carbon.

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