JP3648473B2 - Manufacturing method of silver sintered product - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a silver sintered product, which can produce a silver shaped article having a large craft element such as jewelry, arts and crafts, and ornaments at home by a simple method.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a method using a silver clay composition is known as a method for obtaining a silver shaped article having a large craft element such as jewelry, art crafts, and ornaments.
The silver clay composition contains silver powder, binder, and solvent as basic materials, and is further mixed with oils and plasticizers to prevent adhesion of surfactants and hands as mixing accelerators. Are already on the market. As the binder, a water-soluble cellulose resin as a main component, and a surfactant and oil are added. This silver clay composition is shaped into an appropriate shape, dried and solidified, dried, and then heated in an electric furnace or kiln in a temperature range lower by about 250 ° C. to 10 ° C. than the melting point of silver (about 960 ° C.). The target silver sintered product is obtained by decomposing and removing the binder by evaporative combustion or the like and sintering the particles of the silver powder. Therefore, in order to obtain a silver sintered product, an electric furnace or kiln equipped with a facility for controlling the temperature in the range of about 250 ° C. to 10 ° C. lower than the melting point of silver, ie, about 710 to 950 ° C. is required. The
[0003]
[Problems to be solved by the invention]
However, since the electric furnace, kiln, etc. are relatively expensive, even if a commercially available silver molding clay composition can be obtained and shaped appropriately, the subsequent processing (sintering) is free. It was not something that could be done.
In addition, heating and sintering a silver clay shaped body using a gas burner torch without using an electric furnace or the like causes the flame of the gas burner torch to reach a temperature exceeding 1000 ° C. The operation of applying a flame instantaneously so as not to melt (heat melt) was extremely difficult and required skill.
Therefore, the present invention proposes a method for obtaining a silver sintered product very easily without requiring skill by using a gas stove (including a cassette stove) using household city gas or LP gas. For the purpose.
[0004]
[Means for Solving the Problems]
The present invention has been proposed in view of the above, and makes a molded article from a silver clay composition composed of an organic binder mainly composed of cellulose resin with a silver powder of 60 to 95 wt%, or a heat resistant material. After being attached and dried, it is placed on a metal net with a mesh size of 1.5 to 2.0 mm and heated with a burner of a household gas stove for 5 to 15 minutes so that the density ratio becomes 50 to 90%. The present invention relates to a method for producing a sintered silver product characterized by being sintered into
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The silver clay composition used in the present invention is not particularly limited as long as the silver clay composition is composed of 60 to 95 wt% of silver powder and the balance is composed of an organic binder mainly composed of a cellulose resin. Any silver powder, organic binder, or other additive may be used.
[0006]
The silver powder is a powder having an average particle size of about 1 to 20 μm, and the particle shape is mainly a spherical, irregular, or flat powder, and is not limited to these, but has an average particle size of 1 to 20 μm. When spherical particles are used, the porosity after sintering decreases, the degree of sintering increases, the physical properties such as strength of the sintered product improve, and the sintered product has characteristics such as easy finishing such as polishing. To be.
[0007]
As the organic binder, a water-soluble cellulose resin is used as a main component, and surfactants, fats and oils are appropriately added as necessary, and 40 to 5 wt% with respect to 60 to 95 wt% of the silver powder. Blended. As an example of a specific and preferable blending ratio, water-soluble cellulose resin 0.4 to 10 wt%, starch 0.4 to 3 wt%, fat and oil 0.05 to 3 wt%, surfactant 0.05 to 3 wt%, the balance An organic binder using water as a solvent is used.
[0008]
The silver powder and the organic binder are mixed to obtain a silver clay composition, but the concentration may be adjusted by appropriately adding water or alcohols. In other words, when modeling with a hand or a spatula as a clay-like composition having no fluidity, it is injection-molded with a syringe as a paste-like composition having a high fluidity, or a heat-resistant material such as a brush. When adhering to the surface, the concentration is adjusted to a low level.
Various methods for modeling are devised as clay crafts such as transferring plant leaf patterns, so they can be used to avoid detailed explanations. Moreover, the silver clay composition in this invention is applicable also to the use conventionally painted around the edge of ceramic products etc. using the special silver liquid (sulfuric acid terpene silver). That is, the heat-resistant material has an arbitrary shape selected from ceramic products such as porcelain products, ceramic products, heat-resistant metal products, and heat-resistant minerals, and does not cause deformation or the like due to heat during sintering. Can be used.
[0009]
The metal net used in the present invention has a mesh size of 1.5 to 2.0 mm, the wire constituting the net is about 0.5 to 2 mm, preferably about 1.0 mm, and the material is particularly limited. Although not intended, stainless steel wire is preferred. When the mesh size of this metal mesh is larger than 2.0 mm, the gas flame passes completely through the mesh, and the highest temperature of the flame exceeds the melting point of silver (about 960 ° C) and reaches 1000 ° C or more. Therefore, the highest temperature part of the flame directly hits the silver model and melts the silver. When the mesh size is smaller than 1.5 mm, the passage of the flame is blocked but the passage of the heat flow is also blocked, so the heat conduction efficiency is also deteriorated, and the sintering temperature (a temperature range about 250 ° C. to 10 ° C. lower than the melting point of silver, That is, since it does not reach the range of about 710 to 950 ° C., it cannot be sintered.
Sintering is nothing but sintering of silver powder particles, but here the density ratio is 50% or more, and it has sufficient strength and physical characteristics to withstand finishing such as polishing finish. It means to become a sintered body. Although this metal net is different from general-purpose fish grills, the equipment cost is much lower than that of electric furnaces and kilns, and it can of course be used repeatedly.
[0010]
Further, the household gas stove used in the present invention may be a city gas or LP gas that is usually piped in a general house, or may be a cassette stove.
[0011]
In the present invention, a molded object such as a ring or broach is made from the silver clay composition, or is attached to a heat-resistant material such as a ceramic dish and dried, and then placed on the metal net to burn a burner for a household gas stove. To sinter for 1-15 minutes. Since the silver clay model placed on the metal net is transferred from the lower end in contact with the net and transferred upward, it is sintered as a whole. I don't need it. If the heating time is less than 5 minutes, heat transfer to the silver sintered body may be insufficient and sintering with a density ratio of 50% or more may not be obtained. If the heating time exceeds 15 minutes, no further effect can be expected, resulting in energy loss.
[0012]
【Example】
〔Preliminary experiment〕
A stainless steel net with mesh sizes of 1.0 mm, 1.5 mm, 2.0 mm, and 3.0 mm is placed on the burner base of a household gas stove that uses LP gas as fuel gas, and the gas is ignited. The temperature of the red-hot part was measured with a thermocouple. The diameter of the stainless steel wire of the mesh was 1.0 mm.
When a mesh having a mesh size of 1.0 mm was used, the temperature after 1 minute and 15 minutes after ignition of the gas was 580 ° C.
When a mesh having a mesh size of 1.5 mm was used, the temperature at 1 minute and 15 minutes after ignition of the gas was 850 ° C.
Even when a mesh having a mesh size of 2.0 mm was used, the temperature after 1 minute and 15 minutes after ignition of the gas was 850 ° C.
When a mesh having a mesh size of 3.0 mm was used, the temperature after 1 minute and 15 minutes after ignition of the gas was 1050 ° C. However, in this case, since the flame had passed through the net and protruded on the net, a measurement was made at a location 2.0 mm away from the net.
From these results, the burner flame and the temperature atmosphere on the mesh can be controlled by the mesh size of the metal mesh, and the protrusion of the burner flame is suppressed when the mesh size of the metal mesh is 1.5 to 2.0 mm. At the same time, the temperature atmosphere on the net can be controlled to about 850 ° C. (= temperature lower by 110 ° C. from the melting point of silver), and it was confirmed that conditions suitable for silver sintering were formed.
[0013]
[Example 1]
A silver clay composition was prepared by kneading 92 wt% of pure Ag powder having an average particle size of 20 μm, 0.4 wt% of methylcellulose, 0.4 wt% of starch, and 7.2 wt% of water.
A piece of 5 cm × 2 cm × 1 cm was prepared from this silver clay composition, and dried and solidified for 1 hour with a dryer at 100 ° C.
Next, a stainless steel mesh (mesh size 2.0 mm, stainless steel wire diameter 1.0 mm, size 180 mm x 180 mm) is placed on a burner stand of a household gas stove (5.35 kw) using LP gas, and gas is supplied. When ignited, the center of the net became red hot as shown in FIG.
A dried and solidified piece was placed on the red-hot portion and heated for 1 minute to obtain a silver sintered body that became white like a pear skin. This silver sintered body had a density of 5.53 g / cm ³ and a density ratio of 53%. When heated for 15 minutes under the same conditions, the obtained silver sintered body had a density of 8.57 g / cm ³ and a density ratio of 82%.
[0014]
[Example 2]
A silver clay composition was prepared by kneading 92 wt% of pure Ag powder having an average particle size of 20 μm, 0.4 wt% of methylcellulose, 0.4 wt% of starch, and 7.2 wt% of water.
A piece of 5 cm × 2 cm × 1 cm was prepared from this silver clay composition, and dried and solidified for 1 hour with a dryer at 100 ° C.
Next, place a stainless steel mesh (mesh size: 2.0 mm, stainless steel wire diameter: 1.0 mm, size: 180 mm x 180 mm) on the burner stand of a household gas stove (4.65 kw) using city gas. When ignited, the center of the net became red hot as shown in FIG.
A dried and solidified piece was placed on the red-hot portion and heated for 1 minute to obtain a silver sintered body that became white like a pear skin. This silver sintered body had a density of 5.32 g / cm ³ and a density ratio of 51%. When heated for 15 minutes under the same conditions, the obtained silver sintered body had a density of 8.41 g / cm ³ and a density ratio of 80%.
[0015]
Example 3
A silver clay composition was prepared by kneading 92 wt% of pure Ag powder having an average particle size of 20 μm, 0.4 wt% of methylcellulose, 0.4 wt% of starch, and 7.2 wt% of water.
A piece of 5 cm × 2 cm × 1 cm was prepared from this silver clay composition, and dried and solidified for 1 hour with a dryer at 100 ° C.
Next, a stainless steel mesh (mesh size 2.0 mm, stainless wire diameter 1.0 mm, size 180 mm × 180 mm) is placed on the burner base of the cassette stove (2.5 kw), and the gas is ignited. The center of the net was red hot like a circle.
A dried and solidified piece was placed on the red-hot portion and heated for 1 minute to obtain a silver sintered body that became white like a pear skin. This silver sintered body had a density of 5.25 g / cm ³ and a density ratio of 50%. When heated for 15 minutes under the same conditions, the obtained silver sintered body had a density of 7.46 g / cm ³ and a density ratio of 71%.
[0016]
Example 4
A silver clay composition was prepared by kneading 92 wt% of pure Ag powder having an average particle size of 20 μm, 0.4 wt% of methylcellulose, 0.4 wt% of starch, and 7.2 wt% of water.
A ring was made from this silver clay composition, and dried and solidified in a dryer at 100 ° C. for 1 hour.
Next, a stainless steel mesh (mesh size 2.0 mm, stainless steel wire diameter 1.0 mm, size 180 mm x 180 mm) is placed on a burner stand of a household gas stove (5.35 kw) using LP gas, and gas is supplied. When ignited, the center of the net became red hot in a circular shape.
A dried and solidified piece was placed on the red-hot part and heated for 5 minutes to obtain a silver sintered body that became white like a pear skin. When this silver sintered body was polished with a stainless brush and further polished with a polishing spatula, a silver mirror surface appeared and a beautiful silver ring could be created.
[0017]
Example 5
A paste-like silver clay composition was prepared by kneading 82 wt% of pure Ag powder having an average particle size of 20 μm, 0.4 wt% of methylcellulose, 0.4 wt% of starch, and 17.2 wt% of water. This paste-like silver clay composition was applied to the leaf, and dried and solidified in a dryer at 100 ° C. for 1 hour.
Next, a stainless steel mesh (mesh size 2.0 mm, stainless steel wire diameter 1.0 mm, size 180 mm x 180 mm) is placed on a burner stand of a household gas stove (5.35 kw) using LP gas, and gas is supplied. When ignited, the center of the net became red hot in a circular shape.
A dried and solidified piece was placed on the red-hot part and heated for 5 minutes to obtain a silver sintered body that became white like a pear skin. When this silver sintered body was polished with a stainless brush and further polished with a polishing spatula, a silver mirror surface appeared and a beautiful silver brooch in the shape of a leaf could be created.
[0018]
Example 6
A silver clay composition was prepared by kneading 92 wt% of pure Ag powder having an average particle diameter of 20 μm, 0.6 wt% of methylcellulose, 0.1 wt% of polyethylene glycol, 0.1 wt% of dioctyl phthalate, and 7.2 wt% of water.
The silver clay composition was stretched into a string and braided to form a ring, which was dried and solidified in a dryer at 100 ° C. for 1 hour.
Next, a stainless steel mesh (mesh size 2.0 mm, stainless steel wire diameter 1.0 mm, size 180 mm x 180 mm) is placed on a burner stand of a household gas stove (5.35 kw) using LP gas, and gas is supplied. When ignited, the center of the net became red hot in a circular shape.
A dried and solidified piece was placed on the red-hot part and heated for 5 minutes to obtain a silver sintered body that became white like a pear skin. When this silver sintered body was polished with a stainless brush and further polished with a polishing spatula, a silver mirror surface appeared and a beautiful silver ring could be created.
[0019]
[Comparative Example 1]
A silver sintered body was similarly obtained except that a stainless steel mesh (mesh size: 3.0 mm, stainless steel wire diameter: 1.0 mm, size: 180 mm × 180 mm) was used instead of the stainless steel mesh in Example 3. However, the flame of the burner reached the stainless steel net, and the silver model was melted in about 3 minutes.
[0020]
[Comparative Example 2]
The same treatment was performed except that a stainless steel mesh (mesh size 1.0 mm, stainless steel wire diameter 1.0 mm, size 180 mm × 180 mm) was used instead of the stainless steel mesh in Example 1.
The silver sintered body obtained by heating for 1 minute had a density of 4.52 g / cm ³ and a density ratio of 43%. When heated for 15 minutes under the same conditions, the obtained silver sintered body had a density of 4.95 g / cm ³ and a density ratio of 47%. Furthermore, when heated for 30 minutes under the same conditions, the obtained silver sintered body had a density of 4.98 g / cm ³ and a density ratio of 47%. All silver sintered bodies were broken when polished with a stainless steel brush.
[0021]
As mentioned above, although the Example of this invention was shown, this invention is not limited to the said Example, Unless it changes the structure as described in a claim, it can implement in any way. In addition, although silver powder was used in the present invention, it is possible to control the temperature atmosphere on the net while suppressing the protrusion of the burner flame by using a specific metal net, and the same temperature conditions other than silver sintering The use of a clay composition using a precious metal powder that can be sintered at (about 850 ° C.) is also foreseen.
[0022]
【The invention's effect】
As described above, the method for producing a silver sintered product according to the present invention uses a metal mesh of a specific mesh size to suppress the flame of a burner of a household gas stove from protruding on the mesh and the temperature atmosphere on the mesh. Can be controlled below the melting point of silver, and a sintering process that had to be performed using an expensive electric furnace or kiln so far can be carried out very easily at home.
Therefore, a commercially available silver clay composition can be purchased, and a desired shaped article, for example, an accessory can be appropriately produced by craft means, and this can be easily sintered at home to make a silver accessory.
[Brief description of the drawings]
FIG. 1 is a plan view showing an example of a method for producing a silver sintered product performed in Examples.

Claims (1)

A silver powder 60 to 95 wt%, the balance is made of a silver clay composition composed of an organic binder mainly composed of a cellulose resin, or a model is made by adhering to a heat-resistant material and dried, and then mesh size 1. Silver sintering characterized by being placed on a metal mesh of 5 to 2.0 mm and heated to a density ratio of 50 to 90% by heating with a burner of a household gas stove for 1 to 15 minutes Product manufacturing method.

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