JPH059645A - Golden sintered alloy - Google Patents

Abstract

PURPOSE:To produce a golden sintered alloy having excellent chipping resistance and easy to work with sharp edges by blending specified percentages of Ti, Fe family metals, group VIa elements of the periodic table and nonmetallic elements and specifying average grain size. CONSTITUTION:A golden sintered alloy consisting of >=55wt.% Ti, <=29wt.% Fe family metals (Ni, Fe and Co) and group VIa elements (Cr, Mo and W) of the periodic table and the balance nonmetallic elements (N and C) and having <=3mum average grain size is prepd. In the sintered body, Ti is chiefly in existence TiN or TiCN and forms a hard phase. The pref. amt. of the Fe family metals is about 1-20wt.% and that of the group VIa elements of the periodic table is about 1-20wt.%. The golden sintered alloy has a fine color tone and does not cause corrosion and scratch over a long period of time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gold-colored sintered alloy having a gold color used for decoration, for example.

[0002]

2. Description of the Related Art Conventionally, for example, as a gold-colored material used for decoration, pure gold, alloys of these metals, various metals such as brass, or metal plated with gold has been used. All of them have low hardness, so that they have a drawback that the surface is apt to be scratched by contact with a hard substance and cracks are generated.

Therefore, in recent years, in order to solve the above-mentioned disadvantages, a metal-nitride, for example, a gold-colored sintered alloy in which titanium nitride or the like is bonded with a metal such as Ni or Co has come to be used. (See Japanese Patent Publication No. 2-58335, etc.).

[0004]

However, although the gold-colored sintered alloy containing a metal nitride has high strength and exhibits a gold color, it is inferior in chipping resistance and is susceptible to shedding or the like during decoration processing, resulting in sharp edges. There was a problem that processing was difficult.

[0005]

[Means for Solving the Problems] The inventors of the present invention have conducted various studies in order to obtain a gold-colored sintered alloy having excellent chipping resistance and capable of easily performing sharp edge processing. It was found that the above effects can be obtained by limiting the average crystal grain size in the bound body to a predetermined value or less.

That is, the gold-colored sintered alloy of the present invention contains 55% by weight or more of titanium in the total amount, iron group metal and 6a of the periodic table.
The group element is 29% by weight or less in the total amount, the rest is composed of a non-metal element, and the average crystal grain size is 3 μm or less. The iron group metals include Ni and F
e, Co, and Cr as the Group 6a element of the periodic table,
There are Mo and W, and non-metal elements include nitrogen and carbon.

The reason why Ti is 55% by weight or more based on the total amount is that if the amount of Ti is less than 55% by weight, the gold color tone becomes light. This amount is preferably 60 to 75% by weight. Incidentally, Ti is mainly T in the sintered body.
It exists as iN or TiCN and forms a hard phase.

Further, the iron group metal and the Group 6a element of the periodic table are set to 29% by weight or less in the total amount. The reason is that if the amount is more than 29%, the hardness of the sintered body is remarkably lowered. This is because the corrosion resistance decreases as well. The amount of the iron group metal and the group 6a element of the periodic table is preferably 10 to 29% by weight. The iron group metal forms a binder phase in the sintered body, and the Group 6a element of the periodic table forms the hard phase or the binder phase. Further, specifically, it is desirable that the iron group metal is present in a proportion of 1 to 20% by weight and the Group 6a element of the periodic table is present in a proportion of 1 to 20% by weight.

The average grain size of the gold-colored sintered alloy is 3 μm.
The reason why it is set to m or less is that if it is larger than 3 μm, crack extension becomes remarkable, large chipping occurs during grinding, and sharp edge processing cannot be performed.
On the other hand, when the average crystal grain size is 3 μm or less, sharp edge processing can be easily performed. this is,
Since ceramics is a brittle material, it is weak against impact and easily cracks. However, if the average crystal grain size is 3 μm or less, when stress is applied to the particles by grinding or the like, the stress applied to each particle is It is considered that since the particle size becomes smaller, it is less likely that shedding or the like will occur. The balance contains a small amount of unavoidable impurities.

Further, in the gold-colored sintered alloy of the present invention, as a raw material powder, Ti nitride and carbonitride powder are mixed with an iron group metal such as Ni and an element of Group 6a of the periodic table such as W and Cr. After being mixed and pulverized in an organic solvent such as acetone for a predetermined time, a binder is added in a predetermined amount and pressure-molded into a desired shape at a predetermined pressure, and the binder is debindered at a predetermined temperature in a non-oxidizing atmosphere, It is obtained by firing at a predetermined temperature. For example, TiN and TiC having a particle size of 0.5 to 3.0 μm as Ti nitride and carbonitride.
N, Ni or Co having a particle size of 0.1 to 1.0 μm as an iron group metal, and a particle size of 1.0 to 1 as a Group 6a element of the periodic table.
Weigh and mix 0.0 μm WC and Cr ₃ C ₂ powders,
This is mixed and pulverized in an organic solvent such as acetone for about 68 hours, paraffin is added, and pressure molding is performed at 1.5 ton / cm ² into a desired shape. It is obtained by debinding the molded product at a predetermined temperature in a non-oxidizing atmosphere, and then performing vacuum firing at a predetermined temperature for 1 hour in a vacuum heating furnace. At this time, W or Cr is added as a carbide as a raw material powder, and is melted in the binding metal as metal W or metal Cr in the process of firing, or solid-dissolved in TiN or TiCN to form WC or Cr ₃ C ₂ Does not exist. Also, T
It is desirable that iN and TiCN exist as crystal particles having a particle size of 10 μm or less.

As a firing method, the degree of vacuum is 10 ^-1 to 10 ^-4.
Firing is performed at a temperature of 1300 to 1800 ° C. under reduced pressure or no pressure in a torr atmosphere or various atmospheres.

The gold-colored sintered alloy thus obtained is
For example, it can be used for decoration of watch cases, watch bands, necklaces, broaches, commemorative medals, buttons, scissors, blades, fishing tackle, and the like.

[0013]

EXAMPLES T having a particle size of 0.5 to 3.0 μm as a raw material powder
iN, TiCN with a particle size of 0.5 to 3.0 μm, particle size of 1.0
~ 10.0 μm Cr ₃ C ₂ , grain size 1.0 to 10.0 μ
m WC, grain size 0.1-1.0 μm Ni, grain size 0.1
.About.1.0 .mu.m Co powders were used, and these were weighed and mixed so that the respective metal amounts of the final sintered body were in the ratios shown in Table 1, and were mixed and pulverized in an organic solvent such as acetone for about 68 hours. After that, paraffin is added in an amount of 4 to 5% by weight, and pressure-molded into a desired shape at 1.5 ton / cm ² . After demolding the molded product at a predetermined temperature in a non-oxidizing atmosphere, the degree of vacuum is 1
Temperature of 1400 to 1500 in a vacuum heating furnace of 0 ^-2 torr
Vacuum baking was performed at 0 ° C. for 1 hour. The thus-obtained final sintered body is analyzed by ICP emission spectroscopy or the like,
The results are shown in Table 1.

[0014]

[Table 1]

Then, the sintered body was surface-ground and mirror-polished, after which the color tone, bending strength, Vickers hardness (Hv), average crystal grain size, chipping resistance and corrosion resistance of the sample were tested. The bending strength is measured according to JIS R1601 three-point bending test method, and the Vickers hardness is measured according to JIS Z2.
According to the H. 244 test method, the average crystal grain size is S. E.
It was calculated from the M photograph. Further, the chipping resistance is shown by the maximum chipping width when creep-grinding is performed on the mirror-polished sample. Then, for the corrosion resistance test, artificial sweat (pH 4.7) conforming to the ISO (International Organization for Standardization) standard was used as a corrosive liquid, and the artificial sweat kept at a temperature of 40 ° C. ± 2 ° C.
The lower half of the mirror-polished sample was immersed for 24 hours, and the condition of the polished surface of the sample after immersion was observed. The results are shown in Table 2.

[0016]

[Table 2]

In Tables 1 and 2, the sample numbers marked with * indicate those outside the scope of the present invention. Also,
Regarding the chipping resistance in Table 2, ○ marks are good for sharp edge processing, Δ marks are not suitable for sharp edge processing because chipping occurs in places.
The mark x indicates that chipping frequently occurs and sharp edge processing cannot be performed. Regarding the results of the corrosion resistance test, ○ indicates no discoloration and corrosion, and Δ indicates discoloration.
The mark x indicates that corrosion was observed in addition to discoloration.

As is apparent from Table 2, it was found that the gold-colored sintered alloys of sample numbers 2, 3, 4, 6, 8 and 9 were excellent in chipping resistance. On the other hand, sample numbers 1, 1
In No. 1 gold-colored sintered alloy, the average crystal grain size exceeds 7 μm, chipping frequently occurs, and sample numbers 4, 6, 10
In, the average crystal grain size exceeded 4 μm, and it was difficult to perform sharp edge processing.

[0019]

As described in detail above, in the gold-colored sintered alloy of the present invention, a mirror surface having excellent chipping resistance can be easily revealed.
As a golden sintered alloy with a beautiful color tone that can easily perform the sharp edge processing required for production, and as a result, does not cause corrosion or scratches for a long time, such as watch case,
It can be used for decorations such as watch bands, necklaces, brooches, commemorative medals, buttons, fishing gear, and blades.

Claims (1)

Claims: 1. The total amount of titanium is 55% by weight or more, the iron group metal and Group 6a element of the periodic table are 29% by weight or less,
A gold-colored sintered alloy, characterized in that the balance is composed of non-metallic elements and has an average crystal grain size of 3 μm or less.