JPS5933660B2 - Decorative golden sintered alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a decorative golden sintered alloy, including a material for a watch side, which is non-magnetic and has a golden color at room temperature, which is mainly composed of niobium carbide.

As carbide-based sintered alloys of this kind, alloys mainly consisting of tantalum carbide and alloys mainly consisting of niobium carbide are known, but the former has excellent corrosion resistance and a golden color, but the disadvantage is that the material is too expensive, and the latter has poor corrosion resistance and is not golden in color (it is grayish white).

Similarly, there are alloys based on titanium nitride as nitride-based alloys, which are satisfactory in terms of corrosion resistance, color tone, and price, but have poor wettability with binders, making it difficult to obtain dense and strong alloys. For this reason, it is rarely used for this type of application.

The present invention aims to provide an alloy that eliminates the above-mentioned drawbacks, and its gist is that 30 to 80% by weight of niobium carbide,
10 to 40% by weight of titanium nitride, the balance being nickel, 40% by weight or less of one or more of chromium and molybdenum (not including 0), and 40% by weight of one or more of tungsten and titanium.
This is a decorative golden sintered alloy made of a binder containing the following (excluding 0):

The reason why the content of titanium nitride is set at 10 to 40% by weight is that if it is less than 10% by weight, the color tone becomes grayish white and the corrosion resistance is poor.If it exceeds 40% by weight, the sinterability decreases and the density becomes dense. This is because the properties and strength decrease.

In addition, a bonding material containing nickel, one or more of chromium and molybdenum, and one or more of tungsten and titanium is used because chromium and molybdenum are mainly used to improve corrosion resistance, and tungsten and titanium are used mainly to improve sinterability. The purpose of this is to obtain a sintered alloy that is dense and free of pores.The amount of nickel contained in the nickel as a binder is effective from a small amount, but if the amount is too large, the strength of the alloy decreases due to the decrease in nickel. Therefore, the content should be 40% by weight or less (excluding 0) based on nickel.

Also, if the amount of total binder is less than 10% by weight, the strength will be insufficient.
If it exceeds 30% by weight, the hardness will decrease, so the total amount should be 10~
The content shall be 30% by weight.

Examples of the present invention and comparative examples will be shown below.

Niobium carbide with an average particle size of 1.5 μm, average particle size of 1.5 μm
titanium nitride, nickel with an average grain size of 1.3 μm, chromium with an average grain size of 3.5 μm, molybdenum with an average grain size of 1.3 μm, tungsten with an average grain size of 1.5 μm, and titanium with an average grain size of 325 mesh or less, respectively in Table 1. The mixture was mixed in the ratio shown in the figure below for 120 hours using a wet pole mill, dried, added with paraffin, and press-molded at 1.5 ton/Cm to form a 5.5 mrn xl 0mm x 30
A molded article of mm was obtained.

Further, this molded product was pre-sintered at 800°C in a vacuum atmosphere to remove paraffin, and then sintered at each temperature shown in Table 1 for 50 minutes.
Sintering was carried out for 60 minutes at a vacuum degree of ×10'-2 mmH9°C.

After grinding this fired crystal with a diamond grindstone, its hardness and transverse rupture strength were measured.

Furthermore, after grinding with a diamond grindstone, lapping was performed, and a corrosion resistance test and color tone observation were performed.

In the corrosion resistance test, the degree of cloudiness of the wrap surface after immersion in artificial sweat for 48 hours was examined.

Table 1 shows these results as well as the results for comparative samples obtained in the same manner.

As can be seen from Table 1 above, the alloy of the present invention is comparable to cemented carbide in terms of hardness and transverse rupture strength (for example, WC
In the case of cemented carbide with the composition -5Co, the hardness is HRA93
-94, transverse rupture strength is 110-160), has excellent corrosion resistance, and has a golden color, making it an excellent decorative alloy.

Moreover, the present alloy is non-magnetic at room temperature and has a specific gravity of approximately 8.
It is particularly excellent as a material for watches because it is lighter and cheaper than, for example, tantalum carbide, which has a specific gravity of 14 or more.

Claims (1)

[Claims] 1 Niobium carbide 30-80% by weight, titanium nitride 10-4
0% by weight, the balance being nickel, chromium, and molybdenum.
40% by weight or less (excluding 0) of at least one species, and 40% by weight or less (excluding 0) of one or more of tungsten and titanium
A decorative golden sintered alloy consisting of a binding material containing.