JP3255810B2 - Silver sintered body for decorative parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered body for decorative parts, and more particularly to a sintered body for bracelets, piercings, earrings, eyeglass frames, exterior parts for watches, rings, and the like. TECHNICAL FIELD The present invention relates to a silver sintered body for a decorative component which is preferably used for a decorative component that comes into contact with.

[0002]

2. Description of the Related Art Conventionally, the characteristics required for decorative parts such as watch exterior parts are rich in corrosion resistance, high scratch resistance,
Further, it is required that the metallic luster be maintained for a long time.
As a material having an optimal metallic luster as such a decorative part, stainless steel or metal carbide, for example, W
A sintered alloy in which C or TiC is bonded with a metal such as Ni or Co has been used.

[0003] However, although stainless steel is excellent in corrosion resistance, it is easily scratched due to its low hardness. On the other hand, in the case of a sintered alloy containing WC or TiC as a main component and bonded with a metal element such as Ni or Co, the sintering is difficult. Although there is no problem of the hardness of the body itself, there is a disadvantage that the corrosion resistance to human sweat and seawater is low.

On the other hand, recently, TiB ₂ , which is a boride of titanium, has been developed based on characteristics such as high hardness and corrosion resistance.
Been developed B ₂ based sintered body, it has been put to practical use (see, for example, Publication No. Japanese Patent Publication 59 over 18,458). This TiB ₂ -based sintered body has a bending strength of about 800 to 1000 MPa and a Beakers hardness of about 18 to 24 GPa, and shows excellent characteristics.

[0005]

However, the TiB ₂ -based sintered body described above has a temperature of 1600 to 2000 ° C.
Sintering at a high temperature, and there is a problem that sinterability is low.

In the TiB ₂ -based sintered body described above, N
Since it contained about 1% by weight of a metal binding phase such as i, Co, Cr, etc., when used as a decorative part, there was a risk that some persons might develop metal allergy.

The present invention has excellent properties such as high hardness and corrosion resistance almost equivalent to those of a TiB ₂ -based sintered body.
An object of the present invention is to provide a silver sintered body for decorative parts which can be fired at a low temperature of 00 to 1600 ° C. and can further reduce the content of a metal which causes allergy.

[0008]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, the raw material was Ti
Using the same raw material as that of the B ₂ sintered body,
By mainly producing the iC and TiB phases and making the content of a metal which is an allergic source 0.3% by weight or less, it has almost the same characteristics as a TiB ₂ -based sintered body and has a low temperature of 1300 to 1600 ° C. And found that allergy can be prevented from occurring, leading to the present invention.

That is, the silver sintered body for decorative parts of the present invention is
Silver sintering consisting of at least titanium, carbon, and boron as main constituent elements, and 80 to 95% by weight of titanium, 3 to 12% by weight of boron, and 2 to 8% by weight of carbon based on three components. Wherein the titanium is mainly Ti
It exists as a C phase and a TiB phase and has a metal content of 0.3% by weight or less in the total amount as a source of allergy.

Further, the silver sintered body for decorative parts of the present invention comprises:
A main component 100 comprising at least titanium, carbon, and boron as main constituent elements, and 80 to 95% by weight of titanium, 3 to 12% by weight of boron, and 2 to 8% by weight of carbon based on three components. V, Zr, N
A silver sintered body in which at least one selected from b, Mo, Hf, Ta, and W is present at a ratio of 0.5 to 15.0 parts by weight, wherein a TiC phase and a TiB phase are contained in the sintered body. It is present and has a metal content of 0.3% by weight or less in the total amount as a source of allergy.

Here, the reason why the elements in the sintered body are limited as described above will be described.

First, titanium is contained in an amount of 80 to 80% based on three components.
The reason for setting the content to 95% by weight is that if the content of titanium is less than 80% by weight, the sinterability is reduced and the strength of the sintered body is reduced. This is because phases cannot coexist, and the hardness of the sintered body decreases. Titanium is desirably contained in the total amount of 85 to 90% by weight. Part of titanium may be present as a metal in the sintered body. The amount of the metal present is preferably 40% by weight or less, particularly preferably 30% by weight or less.

The content of boron is set to 3 to 12% by weight of the total amount. If the content of boron is less than 3% by weight, TiB does not exist as a hard phase, and the hardness becomes low. On the other hand, if it exceeds 12% by weight, the diboride TiB ₂
Is increased, and the firing temperature increases. It is desirable that the amount of boron is 4 to 9% by weight based on the total amount.

The reason why the amount of carbon is set to 2 to 8% by weight of the total amount is that if the amount of carbon is less than 2% by weight, TiC as a hard phase does not exist and the hardness becomes low. On the other hand, if the content is more than 8% by weight, carbon remains in the sintered body, and the sinterability decreases. It is desirable that carbon is 3 to 6% by weight based on the total amount.

V, Zr, Nb, M
at least one selected from o, Hf, Ta, and W.
It is desirable to have it present in a proportion of 5 to 15.0 parts by weight, but V, Zr, Nb, M
By containing at least one selected from the group consisting of o, Hf, Ta, and W, mechanical properties such as bending strength, Vickers hardness, and fracture toughness can be further improved. Further, the amount is set to 0.5 to 15.0 parts by weight. When the amount is less than 0.5 part by weight, the effect of improving the mechanical properties is small, and the amount is more than 15.0 parts by weight. In this case, the sinterability tends to decrease, and the strength tends to decrease.
At least one element selected from V, Zr, Nb, Mo, Hf, Ta, and W is desirably present in an amount of 2 to 12 parts by weight. Most of these elements are TiB or TiC
Dissolves in phase to improve properties.

In the present invention, it is desirable that the content of a metal which is a source of allergy is 0.3% by weight or less. Al, Cr, Mn, F
e, Co, Ni, Cu, Zn, Rh, Pd, Cd, S
n and Sb. Further, the reason why the content of such a metal is limited as described above is that if the content is more than 0.3% by weight, metal allergy is likely to occur. That is, in order to prevent metal allergy, the Danish method, which stipulates that the amount of metal as an allergic source to be eluted at 0.5 μg / cm ² / week or less, is a surface technology (vol.
5, No. 9, P910). In the case of the silver sintered body for decorative parts of the present invention, when the content of a metal which is an allergic source is 0.3% by weight or less, the above-mentioned standard is ensured. However, if it exceeds 0.3% by weight, the amount of the metal which is an allergic source may elute more than 0.5 μg / cm ² / week. Allergic easily. Therefore, in the present invention, the content of a metal which is a source of allergy is set to 0.3% by weight or less. 0.1% by weight of allergic metal
It is particularly desirable that:

As described above, in order to reduce the content of the metal causing the metal allergy to 0.3% by weight or less, the above-mentioned metal must not be used as a raw material for producing the sintered body of the present invention. Needless to say, it is effective to use a high-purity raw material having a low content of the aforementioned metal in the raw material.

In the present invention, the most desirable composition is such that titanium is 85 to 90% by weight, boron is 4 to 9% by weight, and carbon is 3 to 6% by weight based on the three components.
Mainly containing a TiC phase and a TiB phase, and further contains 2 to 12 parts by weight of at least one element selected from V, Zr, Nb, Mo, Hf, Ta, and W, and a metal containing an allergic source. The amount is not more than 0.1% by weight of the total amount.

The sintered body of the present invention mainly contains TiC
A phase and a TiB phase are present, and metallic titanium, V, Zr, Nb, Mo, Hf, Ta, and W may be present at these grain boundaries.

The silver-colored sintered body of the present invention is, for example, a mixture of titanium powder and titanium carbide or boride powder as raw material powder, or V, Zr, Nb, M
After mixing and pulverizing an element consisting of o, Hf, Ta, and W, or a mixture of at least one of these carbides and borides, a predetermined amount of a binder is added, and the mixture is pressed and formed into a desired shape at a predetermined pressure. Is debindered at a predetermined temperature in a non-oxidizing atmosphere, and then calcined at a predetermined temperature.

Preferably, for example, the particle size is 0.5 to 3.0.
μm titanium carbide and boride and a particle size of 5-2
50 μm titanium powder and, if desired, a particle size of 1.0 to 1
0.0 μm of V, Zr, Nb, Mo, Hf, Ta and W elements or powders of these carbides and borides are weighed and mixed, and then mixed and ground in an organic solvent such as acetone. A binder is added and molded into a desired shape. Then, the binder is obtained by removing the binder at a predetermined temperature in a non-oxidizing atmosphere and then performing vacuum firing at a predetermined temperature.

Here, the boride of titanium is Ti
Any of B ₂ and TiB can be used. When TiB ₂ is used as a raw material, this TiB ₂ and metal Ti
React at 1300-1600 ° C. to produce TiB.

It is desirable that TiB be present as needle-like crystals in the sintered body, but it does not have to be needle-like.

It is necessary for the raw material to be used so that the content of metal as an allergic source is not more than 0.3% by weight of the whole raw material.

As the firing method, the degree of vacuum is 10 ^-1 to 10 ^-5.
Sintering is performed at a temperature of 1300 to 1600 ° C. under reduced pressure or no pressure in a torr atmosphere or various atmospheres. Further, in a non-oxidizing atmosphere, in hot isostatic firing (HIP),
It is desirable to fire at 1200 to 1400 ° C. under 100 to 2000 atm. The firing time is usually 0.5 to 5 hours, depending on the size of the sample. After firing, the surface of the sintered body is mirror-polished with a diamond paste or the like, so that a glossy silver color appears.

In the silver sintered body of the present invention, the sintered body contains 80 to 95% by weight of titanium in the whole amount and 3 to 12% of boron in the whole amount.
The TiC phase and the TiB phase can be present as crystal phases by adjusting the raw material composition so that the content of carbon is 2 to 8% by weight in the total amount.

In the silver-colored sintered body of the present invention, as long as the composition range of the present invention is satisfied, even if it contains a small amount of impurities, other compounds, and metals, there is no effect on the characteristics.

[0028]

In the silver sintered body for decorative parts of the present invention, the TiC phase in the sintered body contributes to imparting silver color, and the TiB phase improves mechanical properties such as transverse rupture strength, Vickers hardness and fracture toughness. Contribute. In the present invention, the sintered body is mainly made of Ti
Since it is composed of the C phase and the TiB phase, it has a glossy silver color, can obtain excellent bending strength, Vickers hardness, and fracture toughness, and can be fired at a low temperature of 1300 to 1600 ° C.

V, Zr, Nb, Mo, Hf, T
By containing a and W, mechanical properties such as strength, hardness, and fracture toughness can be further improved.

Further, in the silver sintered body for decorative parts of the present invention, since the content of a metal which is a source of allergy is 0.3% by weight or less, the occurrence of allergy can be surely prevented. Such a silver-colored sintered body can be used, for example, for decoration of a watch case, a watch band, a necklace, a bracelet, etc., and for scissors, cutlery, fishing gear, etc., and also used for other tools and machine parts. Can be.

[0031]

【Example】

Example 1 TiC and Ti having an average particle size of 1.1 μm as raw material powders
B ₂ , using a Ti powder having a particle size of 40 μm, weighing and mixing them in the ratio shown in Table 1, mixing and pulverizing them in an organic solvent such as acetone for about 68 hours, and then adding 6% by weight of paraffin; It is pressed into a desired shape at 2.0 ton / cm ² . The molded product is subjected to 40 in a non-oxidizing atmosphere.
After debinding at 0 ° C., vacuum firing was performed for 1 hour at a temperature shown in Table 1 in a vacuum heating furnace having a degree of vacuum of 10 ⁻³ torr. The firing was performed by adjusting the atmosphere so that the composition did not change.

[0032]

[Table 1]

The crystal phase of the final sintered body thus obtained was identified by X-ray diffraction measurement. As a result, it was confirmed that each of the products of the present invention mainly contained a TiC phase and a TiB phase. The final sintered body was analyzed by ICP emission spectroscopy, and the results are shown in Table 1. In addition, the content of a metal as an allergic source was measured by ICP emission spectroscopy. In Table 1, since only Ni and Fe were found as the metals serving as allergic sources, the contents of Ni and Fe are described.

In Table 1, the presence or absence of metallic titanium is determined by
The case where the presence of metallic titanium was confirmed by both X-ray diffraction measurement and SEM observation of the structure was evaluated as 、. The case where X-ray diffraction measurement could not be confirmed but the structure was confirmed by SEM was observed as Δ. The case where it could not be confirmed even by the structure observation was evaluated as x. Figure 1 shows the organization chart by SEM.
Shown in In FIG. 1, reference numeral 1 denotes a TiC phase, and 2 denotes a TiB phase.

Then, the sintered body is subjected to surface grinding and mirror polishing, and thereafter, a transverse rupture strength, a Vickers hardness (Hv), a fracture toughness value, a corrosion resistance, and a metal elution test are performed, and the color of the sintered body is visually checked. confirmed.

The bending strength was measured according to the three-point bending test method of JIS R1601, and the Vickers hardness was measured according to JIS Z2.
244 test method was followed. The fracture toughness was determined by the IF method. The corrosion resistance test was performed using artificial sweat (pH 4.7) conforming to the ISO (International Organization for Standardization) standards as a corrosive liquid, and a mirror-polished sample was placed in artificial sweat maintained at a temperature of 37 ° C. ± 2 ° C. After soaking for a week, the state of the polished surface was observed, and the degree of corrosion was visually observed. The case where the polished surface was not corroded was evaluated as ○, and the case where the polished surface was slightly corroded was evaluated as △. In addition, the samples of the present invention visually confirmed that a glossy silver color appeared in all samples. Table 2 shows the results.

[0037]

[Table 2]

From these Tables 1 and 2, the specimen of the present invention has a flexural strength of 700 to 1000 MPa, a Vickers hardness of 10.0 to 13.5 GPa, and a fracture toughness of 5.0 to 5.0.
It is 6.8 MPa · m ^1/2 , which indicates that the corrosion resistance is good.

It is also found that the sample of the present invention has a metal content of 0.3% by weight or less as a source of allergy.
Therefore, occurrence of metal allergy can be reliably prevented.

Example 2 TiC and Ti having an average particle size of 1.1 μm were used as raw material powders.
B ₂ , an element composed of V, Zr, Nb, Mo, Hf, Ta, and W having a particle diameter of 40 μm, Ti powder having an average particle diameter of 1.0 μm,
Or, using those carbides or borides, these are weighed and mixed so that the respective metal amounts of the final sintered body become the ratios in Table 3, and then mixed and ground in an organic solvent such as acetone for about 68 hours. Add 6% by weight of paraffin, 2.0 ton
/ Cm ² under pressure to a desired shape. After debinding the molded product at 400 ° C. in a non-oxidizing atmosphere, the temperature was reduced to 1 in a vacuum heating furnace having a degree of vacuum of 10 ⁻³ torr.
Vacuum firing was performed at 450 ° C. for 1 hour. Further, hot isostatic firing (HIP) was performed at 1300 ° C. for 1 hour in an argon atmosphere. The crystal phase and the metal element of the final sintered body thus obtained were analyzed, and the content of metal as an allergic source was determined in the same manner as in Example 1 above. Table 3 shows the results.

[0041]

[Table 3]

Then, the sintered body was subjected to surface grinding and mirror polishing, and thereafter, a bending strength, Vickers hardness (Hv), fracture toughness value, corrosion resistance and metal elution test were carried out in the same manner as in Example 1 above. Further, the color of the sintered body was visually confirmed. In the samples of the present invention, as a result of visual observation, it was confirmed that glossy silver color appeared in all samples.

Table 4 shows the results.

[0044]

[Table 4]

From Tables 3 and 4, it can be seen that by including at least one of V, Zr, Nb, Mo, Hf, Ta and W in the sintered body, the bending strength and Vickers hardness are particularly improved. You can see that Further, it can be seen that the content of the metal which is the allergen source is 0.3% by weight or less.

[0046]

As described above in detail, according to the silver sintered body for decorative parts of the present invention, it has not only practical strength and hardness but also excellent chipping resistance and corrosion resistance, and causes allergy. It contains almost no metal components, and a silver mirror surface easily appears due to the improvement in sintering properties, and as a result, silver ornaments that do not cause corrosion or scratches over a long period of time, such as watch cases, watch bands, and necklaces , Bracelets, buttons, etc.

[Brief description of the drawings]

FIG. 1 shows an organization chart by SEM.

[Explanation of symbols]

 1 ... TiC phase 2 ... TiB phase

Claims (2)

(57) [Claims] (1) at least titanium, carbon and boron as main constituent elements, and 80 to 95 parts by weight of titanium on the basis of three components;
A silver-colored sintered body comprising 3% to 12% by weight of boron, 3 to 12% by weight of boron and 2 to 8% by weight of carbon in the total amount, wherein the sintered body contains a TiC phase and a TiB phase, The silver content of the decorative component is 0.3% by weight or less of the total metal content. 2. Titanium, carbon and boron are the main constituent elements, and titanium is contained in an amount of 80 to 95 in the total amount based on three components.
% By weight, 3 to 12% by weight of boron in the total amount, and 2 to 8% by weight of carbon in 100% by weight of the main component.
A silver-colored sintered body in which at least one selected from V, Zr, Nb, Mo, Hf, Ta, and W is present in a proportion of 0.5 to 15.0 parts by weight, wherein a TiC phase is contained in the sintered body. A silver sintered body for decorative parts, characterized by having a TiB phase and a metal content of 0.3% by weight or less based on the total amount of allergens.