JPH1046282A - Cemented carbide for wristwatch and ornament - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of allergy on skins caused by the incorporation of harmful heavy metals in cemented carbide used for external ornamental parts for ristwatches and oranaments and furthermore to improve its corrosion resistance and hardness. SOLUTION: This cemented carbide has a compsn. contg. TiC, TiN or their mixture by 1 to 40wt.%, NbC, TaC or their mixture by 0.1 to 5.0wt.%, Co, Ni or their mixture by 0.05 to 1.0wt.%, and the balance WC with inevitable impurities. Furthermore, the alloy may contain at least one kind of components selected from TaC, NbC, VC, ZrC, HfC, Mo2 C and Cr3 C2 by 0.1 to 5.0wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cemented carbide used for wristwatches and decorative cosmetics, and in particular, to suppress the occurrence of skin allergies caused by harmful heavy metals, and at the same time, to reduce the corrosion resistance and the glossiness of processed surfaces. The present invention relates to a cemented carbide suitable for improving and increasing hardness and improving scratch resistance.

[0002]

2. Description of the Related Art In general, conditions required for materials of wristwatches and decorative exterior parts include high hardness for ensuring scratch resistance, corrosion resistance to sweat, and non-magnetization.

[0003] As a conventional alloy satisfying such conditions, one disclosed in Japanese Patent Application Laid-Open No. Sho 59-13045 is known, which improves toughness in order to ensure impact resistance and improves corrosion resistance. This is to ensure the nature.

[0004] The above-mentioned conventional alloys are generally expensive Au.
And a large amount of Co, whose distribution is limited worldwide, and various carbides and nitrides. Therefore, the manufacturing cost is high.

In addition, although high hardness is required to provide scratch resistance as an exterior part, its hardness (Hv) is only 1,030-1,100.

On the other hand, since a large amount of Ni itself is a heavy metal harmful to the human body, there is a problem that when used as a wristwatch material, skin allergy is induced.
In cemented carbides, chemical properties such as corrosion resistance are also affected by the binder phase. Since the corrosion of the cemented carbide is caused by the binder metal phase added to the alloy, the corrosion resistance can be improved by removing the binder phase.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems.
By developing a cemented carbide with no binder phase, it suppresses the occurrence of skin allergies due to harmful heavy metals, while improving the corrosion resistance and glossiness of the processed surface, and increasing the hardness,
An object of the present invention is to provide a cemented carbide having improved scratch resistance.

[0008]

According to the present invention, there is provided an alloy comprising:
0% by weight of one component selected from TiC, TiN and mixtures thereof, and 0.05-1.0% by weight of Co,
Ni and one component selected from a mixture thereof, and the remaining components are unavoidable impurities and WC.

[0009] The present invention also relates to an alloy having the above composition.
C, NbC, VC, ZrC, HfC, Mo ₂ C, and C
at least one component selected from r ₃ C ₂
It can be constituted by adding -5.0% by weight.

In the present invention, TaC, NbC, VC, Z
rC, HfC, Mo_TwoC, Cr_ThreeC _TwoIs the suppression of grain growth
To be added in small amounts. In addition, T
iC added, TiN added to improve alloy performance
Have been.

As is well known, when nitrogen is added to a cemented carbide having a basic composition of WC-TiC, grain growth of a nitride phase is suppressed during sintering, and the alloy structure becomes finer. The strength is greatly increased, and the oxidation resistance is improved.

According to the present invention, by adding a very small amount of a binder phase (Co, Ni or one of a mixture thereof) and sintering, there is almost no porosity and grain growth and a complete fine structure is obtained. The alloy is obtained at a relatively low temperature.

When the content of such a binder phase is too small, the grain growth of carbides becomes excessive and the structure becomes uneven, which is not preferable. On the other hand, when the content increases, the strength of the alloy slightly increases, as in the conventional technology, but the amount of carbon decreases and the harmful η phase (eta phase) increases, and the hardness decreases. The gloss also decreases.

Although a binder phase of only Co can be used, it is preferable to use a mixed phase of Co and Ni to increase the strength of the alloy and stabilize the alloy.

Therefore, the first feature of the alloy of the present invention is that the glossiness of the processed surface is excellent as compared with other wristwatches and decorative external parts. This is because there is no binder phase in the structure of this alloy, and it is composed of only very fine and uniform carbides. This is because a high portion does not have fine irregularities caused by less polishing.

In a conventional general cemented carbide, a difference in hardness between a high-hardness carbide phase and a low-hardness bonding metal phase causes topological defects on the surface, resulting in low gloss. Has become.

Second, hardness (Hv) of general cemented carbide
Is about 1,400-1,800 (the above-mentioned Japanese Patent Application Laid-Open No. 59-1).
3045 alloy is only 1,030-1,100), whereas the hardness of the present invention is 2,200H
v or more, and has very high hardness, so that it has excellent scratch resistance.

Although the hardness of the cemented carbide decreases as the amount of the binder phase increases, the hardness of the present alloy can be increased because there is almost no binder phase. Third, since the amount of the binder phase added in the alloy of the present invention is extremely small, there is no problem caused by heavy metals harmful to the material, and no skin allergy occurs even when the material contacts the skin.

Fourth, in the alloy of the present invention, the magnetism is also very low so as to be negligible, and therefore belongs to a non-magnetic material. For example, the magnetic saturation value of the alloy of the present invention is WC-10w
t% Co has a value of about 5% of the magnetic saturation value of the cemented carbide.

Fifth, the alloy according to the present invention is very excellent in corrosion resistance. Corrosion of cemented carbide occurs due to the corrosion of the binder phase contained in the material. Therefore, the material of the present invention containing almost no binder phase has excellent corrosion resistance since the root cause of corrosion is eliminated.

[0021]

Next, embodiments of the present invention will be described. The raw material powder used in the present invention has a relatively fine powder (WC 2 μm or less, Ti) in consideration of surface roughness (gloss) and sinterability.
C, TiN: 1.5 μm or less, TaC, NbC, VC:
1 μm or less, Co: 1 μm, Ni: 4 μm)
The alloy composition ratio was as shown in Table 1. In each of the examples in Table 1, WC was added so as to add up to 100% by weight together with other components.

[0022]

[Table 1] The mixing of the raw material powders was carried out by a wet method. At this time, the charging ratio of the balls to the powder was 3.5: 1, and the mixing speed was 88 rpm.
m. And mixed for 48 hours. The sintering of the alloy was performed at a temperature of 1450 ° C. for 1 hour in a vacuum atmosphere. And H
IP (hot isostatic press) processing 133
The test was performed at 0 ° C. under an argon gas atmosphere at 1200 atm.

[0023]

[Table 2] Table 2 shows the properties of the alloys having the various compositions shown in Table 1. The corrosion resistance evaluation in Table 2 was determined by immersing the alloy in a solution having the composition shown in Table 3 for 48 hours and then examining the degree of turbidity of the alloy surface.

[0024]

[Table 3] The cemented carbide of the present invention is expected to be widely applied to the fields of injection nozzles, compact disk dies, mechanical seals, optical lenses, etc., which require corrosion resistance and high hardness.

[0025]

As described above, the cemented carbide of the present invention has excellent characteristics required for wristwatches and decorative materials, namely, surface roughness, hardness, corrosion resistance, density, non-magnetism, non-toxicity, etc. Since its performance is recognized, it is excellent as a wristwatch and decorative material.

Claims (2)

[Claims] 1. A composition comprising 1-40% by weight of one component selected from the group consisting of TiC, TiN and mixtures thereof;
1.0% by weight of one of the components selected from Co, Ni and mixtures thereof, the balance being composed of unavoidable impurities and WC, for wristwatches and decorative articles. Cemented carbide. 2. The composition according to claim 1, wherein 1-40% by weight of one component selected from TiC, TiN and mixtures thereof,
1.0% by weight of one component selected from Co, Ni and mixtures thereof, and 0.1-5.0% by weight of Ta
C, NbC, VC, ZrC, HfC, Mo ₂ C, Cr ₃
And at least one component selected from the group consisting of C _2, the remaining components are cemented carbide for watches and decorations, characterized in that it is composed of unavoidable impurities and WC.