JPS58204149A - Sintered alloy for decoration - Google Patents

Abstract

PURPOSE:To obtain a sintered alloy for decoration having a decorative effect and corrosion resistance and suitable for use as the material of decorative members such as external decorative parts for a watch by combining a hard phase consisting of prescribed weight percentages of metallic elements such as Ti and Zr and nonmetallic elements with a binding phase of an Fe group metal. CONSTITUTION:This sintered alloy for decoration consists of, by weight, 70- 98% hard phase represented by formula I and 2-30% binding phase of one or more among Fe, Ni, Co, Cr, Mo and W. For example, the sintered alloy has a composition represented by a formula 47.5% TiN0.85-47.5% TiO-5% Ni. Metallic powders for said hard and binding phases are blended in a prescribed ratio, a small amount of paraffin is added as a lubricant, and they are ground and mixed in acetone as a solvent by means of a ball mill. The powdered mixture is dried, press-molded, and sintered at 1,400-1,600 deg.C in vacuum to obtain the desired sintered alloy for decoration.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides exterior parts for watches, tie bins, brooches,
This invention relates to a decorative sintered alloy that is suitable for decorative parts such as fishing parts.

Conventionally, materials for decorative items have been required to have corrosion resistance and scratch resistance. Of these, WC-based, T, and aC-based sintered alloys are expensive and have a large specific gravity, making them unsuitable for use as materials for portable decorative items. The WC-based and TiC1 sintered alloys have the disadvantage that they do not completely meet the requirements for decoration and decoration because they have a dark gray color. To compensate for these drawbacks, coating alloys coated on TIN and/or Tief steels and sintered alloys are used as decorative parts. However, coated alloys may have different color tones between the surface and inside of the coated layer, peeling of the coated layer, or uneven color tone on the coated alloy surface due to changes in the quality and thickness of the coated layer resulting from the manufacturing process. It has the disadvantage of gaining weight when it loses its value as a product. Furthermore, many TiN-based sintered alloys have been proposed as colored sintered alloys for decorative parts, but they have very poor sintering properties, and alloys with poor sintering properties have a mirror-shiny surface. It has not been put into practical use because of the problem that it is not suitable as a member for ornaments that is used in a state.

The decorative sintered alloy of the present invention has three missing pages as described above. All points and problems have been resolved.

In the present invention, TiN
When forming a solid solution in the Fe group, Ti and N cannot be dissolved in equimolar amounts in the Fe group, and about 95% of n- is N.
Since this N2 gas is discharged from the green compact as two gases, after the liquid phase appears, this N2 gas remains and inhibits the promotion of sintering.Based on this phenomenon, we investigated ways to prevent denitrification. The result is a decorative sintered alloy.

The decorative sintered alloy of the present invention includes (Tia, Mh) (Nw, Cx, Oy)
z Hard phase expressed by Te (however, M is Zr, Hf, V
, one or more of Nb, Ta, and Cr, a is the atomic ratio of Ti, b is the atomic ratio of the metal corresponding to M, and a + b =
1.1≧a≧0.4.0.6≧b≧O%N is nitrogen, C
is carbon, 0 is oxygen, WlX, Y is the atomic ratio of nitrogen, carbon, and oxygen, Z is the ratio of nonmetallic constituent elements to metal, W+X+Y=1, x y > o, 1) W2O, 4,
0,5≧X≧0.0.6≧Y≧0.0,95≧Z≧0.
6) is 70 to 98% by weight and Fe, Ni, Co, Cr, M
The binder phase is a sintered alloy containing 2 to 30% of the binder phase selected from O, W, and unavoidable impurities. In the sintered alloy of the present invention, the denitrification that occurs during the process of sintering a TiNy-based green compact is caused by Ti, which has a non-stoichiometric composition.
A phenomenon occurs in which the Nz gas discharged outside the system to make the entire Nz (0,95≧2≧0.6) powder starting material reversely electrifies the T1Nz powder, thereby preventing denitrification.

Also Ti (Nw, Cx, Oy) z f) Like (Ti
By adding carbon and/or oxygen to Nz, the effect of preventing denitrification is strong, and this promotes sinterability, resulting in a dense sintered alloy and a high hardness of the sintered body. A sintered alloy with excellent wear resistance and scratch resistance.

The decorative sintered alloy of the present invention maintains a golden yellow color tone due to the hard phase mainly composed of T1Nz t-, but the color tone ranges from a negative golden color to a pale golden color in which the Z value is less than the stoichiometric composition. TiO, ZrN, and HfN change the color system and make this color tone change even more golden.

VN, NbN, TaN, CrN, CrzN, T
By adding aC and NbCf, it becomes easier to control the color tone from deep pale golden yellow to clear golden yellow.

The decorative sintered alloy of the present invention can be obtained by ordinary sintering in vacuum or in a non-oxidizing atmosphere, but can be obtained by hot isostatic pressure sintering (HIP). A denser and stronger sintered alloy can be obtained.

□Next, the reason for the numerical limitations in the decorative sintered alloy of the present invention will be described.

Hard phase (Ti a, Mb ) (Nw, Cx
”, Oy) In z, metals M other than T! have the effect of suppressing the grain growth of the hard phase and increasing the strength and hardness of the hard phase, but in particular, the metal M other than T! ZrN, 'H'fN, VN, N'bN, which gives objects a golden color
, TaN, CrN, CrzN.
When it is added as a species or more, the mixing ratio between the atomic ratio a of TI and the atomic ratio of M can be selected from a wide range for all alloys, and there is no essential reason to limit this, but it is lightweight for portable use. When adding carbides such as HfC, VC, Cr5Cx, etc., page 6 states that 1≧a≧0.4.
It was determined that 0.6≧b≧O. N and C are non-metallic elements.

0 is Ni-based in order to obtain a golden-colored sintered alloy, and C or O must be contained in one or both in order to promote sinterability and improve scratch resistance. However, if the content is too large, the sinterability will decrease and the hardness of the sintered body will also decrease, so l) W2O,4,0,5≧X≧
0.0,6≧Y≧0. Note that carbon C tends to have a stronger effect on promoting sinterability when added as free carbon than as carbon as a metal carbide. Z, which represents the ratio of nonmetallic elements to metallic elements, needs to be less than the stoichiometric composition in order to prevent outgassing and improve the hardness of the sintered body, but if it is too small, the compound may become defective. 0.95≧2 as it becomes stable and the dimensional accuracy of the sintered body decreases.
It was set as ≧0.6.

The relationship between the amount of hard phase and the amount of binder phase is such that when the amount of hard phase exceeds 98% by weight, the amount of binder phase becomes relatively less than 2% by weight, and the sinterability and compactness decrease.

Furthermore, when the hard phase amount is less than 70% by weight, the page 7 binder phase amount becomes relatively large, exceeding 30% by weight, resulting in a decrease in the hardness of the sintered body and poor scratch resistance.

Based on the above, the amount of hard phase was determined to be 70 to 98% by weight, and the amount of binder phase was determined to be 2 to 30% by weight.

The decorative sintered alloy of the present invention will be specifically described below according to examples.

Example l T1Nz, T iC, T io, T i (Nw,
Cx) z.

T i (Nw, Oy) z, T i (Nw,
Cx, Oy) z and various binder phase metal powders were blended in a predetermined ratio, and after adding 2 g of paraffin as a lubricant, they were pulverized and mixed in a ball mill using an acetone solvent. After drying, the mixed powder was molded at t2t/cd 1O77111 pressure and 140% in vacuum at 10-'-10-'a+Hg.
Sintering was carried out at a temperature of 0°C to 1600°C. The sintered body was ground with a diamond grindstone and polished, and its mechanical properties, color tone, and corrosion resistance were examined. Mechanical properties are measured by hardness and transverse rupture strength.
In addition, the corrosion resistance test was performed in artificial seawater and artificial sweat at 50°C.
This was done by immersing each sample for a day and then observing the entire mirror surface of the sample. The composition and sintering conditions of each sample are shown in Table 1, and the mechanical properties, color tone, and corrosion resistance of each sample after sintering are shown in Table 2.

9 pages 10 pages 1 page Example 2 ZrN, TaN, Tag, NbC, ZrC, VC
, HfN.

CrN, (Tia, Mb)Nz, (Tia,
Mb) (Nw, Cx)z.

(Tia, Mb) (Nw, Oy) z, (T
ia, Mb) (Nw, Cx, Oy) z and each raw material powder used in Example 1 in a predetermined ratio, and a sintered body was prepared using the same manufacturing method as in Example 1. Mechanical properties: Color and corrosion resistance tests were conducted. The composition and sintering conditions of each sample are shown in Table 3, and the mechanical properties, color tone, and corrosion resistance of each sample after sintering are shown in Table 4.

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Example 3 Sample 41.5.8 sintered in Example 1 and Sample A15.19.23 sintered in Example 2 were heated to 1500 bar.
After HIP treatment at -1350°C, mechanical properties, color tone and corrosion resistance tests were conducted. The test results are shown in Table 5.

Claims (1)

[Claims] The hard phase represented by the following formula (g) is 70 to 98% by weight,
(Tia, Mb) (Nw, Cx, Oy)z
--------(A) However, M: Zr, Hf, V, Nb
, Ta, Cr One or more types in CD a+b=1.1≧a≧0.4, α6≧b≧OW+X10Y
=1, x+y>o, 1) W2O,40,5≧X≧0.0
．． 6≧Y≧0, 5≧Z≧Q, 6Fe, Ni, Co
A decorative sintered alloy, characterized in that one or more binder phases selected from , Cr%Mo, Wf) are comprised of 2 to 30% by weight and unavoidable impurities.