JPH0892674A - Decorative titanium alloy and its ornaments - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain specularity and hardness in the production of decorative titanium and titanium alloys by powder metallurgy. [Composition] Iron powder and molybdenum are added to titanium powder,
After compacting, it is sintered to obtain decorative titanium and titanium alloy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decorative article using a titanium alloy, and more particularly to a wristwatch exterior part.

[0002]

2. Description of the Related Art Conventionally, stainless steel has been used for most of decorative materials, particularly wristwatch exterior parts such as bezels and cases, from the viewpoint of corrosion resistance and specularity. In recent years, pure titanium has been used as a material for its corrosion resistance and nickel-induced skin allergy.

[0003]

Conventionally used stainless steels have the following problems: heavy specific gravity, low hardness, rust due to environmental conditions (especially seawater), and easy skin allergy due to nickel. Had. Pure titanium, on the other hand, is superior to stainless steel in terms of lightness, corrosion resistance, and resistance to nickel allergy, but it has problems such as lack of mirror surface and easy scratching, and its design is monotonous. Therefore, there is a problem that a high-class feeling cannot be obtained.

Therefore, an object of the present invention is to improve the specularity and the hardness of decorative titanium and titanium alloys.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention alloys titanium with iron which imparts hardness and molybdenum which imparts densification of structure, thereby increasing hardness and providing a mirror surface. In order to improve the specularity, the specularity was further improved by heating and quenching to the β transformation temperature or higher.

[0006]

According to the above method, since the hardness is increased by iron, it is less scratched, and the composition is densified by molybdenum, so that a decorative article excellent in mirror surface property can be obtained.

[0007]

【Example】

(Example 1) Pure titanium powder having a particle size of 200 μm or less, iron powder having a particle size of 10 μm or less, and molybdenum powder having a particle size of 10 μm or less were mixed, and 0.5 wt% was added to these mixed powders.
Of stearic acid were mixed and molded under a pressure of 30 kgf / mm ² to obtain a molded body. Next, these molded bodies were
Sintering was performed by holding at 1 ° C for 1 hour to obtain a sintered body. The relative density of each sintered body is 95% or more, and the structure is uniform α single phase or α
It becomes a + β two-phase structure and the specularity required for ornaments is obtained. Table 1 shows the composition, hardness, density and specularity of each sintered body. Especially, Vitas hardness Hv18 for pure titanium
Although it is 0, the hardness increases as the amount of iron or molybdenum increases. The hardness of all sintered titanium alloys tested is Hv250 or more, and the hardness of stainless steel Hv200 or more can be exceeded by about Hv50. there were. At the same time, improvement in specularity is also recognized. In particular, as the titanium powder, when the average particle diameter is 20 μm or less, the density is remarkably improved, and the specularity is further improved.

[0008]

[Table 1] (Example 2) Pure titanium powder having a particle size of 200 μm or less, iron powder having a particle size of 10 μm or less, and molybdenum powder having a particle size of 10 μm or less were mixed, and 17 to 18 w were added to these mixed powders.
A t% EVA-St-CWAX-based (vinyl acetate copolymer-stearic acid-carnauba wax-based) organic material was mixed, and a molded body was obtained by injection molding. Next, organic matter is removed from these molded bodies, and then 1200 ° C, 1250 ° C,
Sintering was performed by holding at 1300 ° C and 1350 ° C for 1 hour to obtain a sintered body. The relative density of each sintered body is 95% or more, and the structure becomes a uniform α single layer or a two-phase structure of α + β and the mirror surface property required for ornaments can be obtained Table 2 Composition and hardness of each sintered body・
Shows density and specularity. In particular, titanium has a Vickers hardness of Hv100, but the hardness increases as the amount of iron or molybdenum increases. The hardness of all the sintered titanium alloys tested is Hv250 or more, and the hardness of stainless steel Hv200 or more can be exceeded by about Hv50. there were. At the same time, an improvement in specularity is also recognized. In particular, as the titanium powder, when the average particle diameter is 20 μm or less, the density is remarkably improved, and the specularity is further improved. In particular, a density increase of 2 to 3% was observed as compared with the powder compacting, and the mirror surface property was further improved.

[0009]

[Table 2] According to this method, the hardness becomes about 20% higher than that in Example 1 due to the oxidation and nitriding that occur when removing the organic matter. (Example 3) Each sintered body was heated to 3 at 950 ° C, which is higher than the β transformation temperature.
It was heated for 0 minutes and quenched by oil cooling (β solution treatment). By subjecting the tested titanium alloy (containing 0.1 wt% or more of iron and 0.1 wt% or more of molybdenum) to the solution treatment, the hardness is hardly changed, but the structure is refined. Each of the sintered bodies after the solution treatment was subjected to buffing for mirror finish. As a result, the specularity was remarkably improved. Table 3 shows the hardness and specularity of each sintered body after the solution treatment.

[0010]

[Table 3]

[0011]

According to the present invention, there is an effect that a titanium alloy having high hardness and excellent mirror surface property can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yutaka Wakabayashi 6-31-1, Kameido, Koto-ku, Tokyo Seiko Electronics Co., Ltd. (72) Inventor Akiya Shishido 6-31-1, Kameido, Koto-ku, Tokyo No. Seiko Denshi Kogyo Co., Ltd. (72) Inventor Tetsuya Kondo 4, 1809 Toda, Nakagawa-ku, Nagoya, Aichi

Claims (3)

[Claims] 1. A mixed powder containing 0.1 to 1.0% by weight of iron powder and 0.1 to 4.0% by weight of molybdenum powder, and the balance of titanium powder after compacting 1200. ~ 1
A decorative titanium alloy characterized by being sintered at 350 ° C. 2. A mixed powder containing 0.1 to 1.0% by weight of iron powder and 0.1 to 4.0% by weight of molybdenum powder, and the balance of titanium powder being kneaded with an organic substance, A decorative titanium alloy, characterized in that an organic material is removed from a molded body obtained by injection molding the kneaded product, and then sintered at 1200 to 1350 ° C. 3. The decorative article according to claim 1 or 2, wherein after sintering, after heating to a β transformation point temperature or higher, and then cooling at a rate of hot water cooling or higher, the surface is polished to be mirror-finished. .