JPS6023192B2 - Method for manufacturing oxide-dispersed silver alloy wire - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for producing an oxide-dispersed silver alloy wire.

Oxide-dispersed silver alloys, in which oxide particles such as cadmium oxide, indium oxide, tin oxide, antimony oxide, zinc oxide, and manganese oxide are dispersed in silver, have good electrical conductivity and are resistant to deposition under arc heat and Joule heat. Because of its excellent wear resistance, it is used as an air contact in a wide range of applications, including electromagnetic switches, relays, thermostats, and no-fuse breakers. These alloys have oxide-forming elements dissolved in silver,
It is often produced by a so-called internal oxidation method in which solute elements are selectively oxidized by heating in an oxygen-containing atmosphere and oxides are dispersed. The first advantage of this manufacturing method is that it is easy to control the dispersion state of the oxide, which is convenient for fully enhancing the above-mentioned performance.

Second, silver does not oxidize even in oxygen, making it easy to form an internal oxidizing atmosphere, resulting in excellent manufacturability.

However, there are the following problems, and the shape that can be applied is
There were size restrictions. That is, the first problem is the alloy composition, particularly the uniformity of the dispersion state of the oxide. Although the oxide is gradually dispersed from the surface layer by heating in an oxygen-containing atmosphere, the particle size and dispersion state of the oxide in the center and surface layers are different, which may reduce the contact performance in the center. In order to obtain stable characteristics, the surface portion was often used as the contact surface of the contact. The second problem is a dimensional problem.

That is, when proceeding with internal oxidation from the surface layer, it takes a very long time to oxidize a large material to the center, which causes problems in production. In addition, the longer the oxidation time, the more significant the non-uniformity of the oxide dispersion between the center and the surface becomes.
If these problems can be eliminated, the cross section of the alloy can be used as the contact surface, so it is possible to manufacture the alloy wire and continuously manufacture contacts in which the alloy is bonded to a part of the support by header processing. The alloy pieces, which were previously manufactured by punching, can now be manufactured quickly and easily by cutting out bamboo wood using trout cutting, which not only expands the scope of use of the alloy, but also improves productivity. You can also expect

By the way, as a result of research on various alloys, it has become clear that the non-uniformity of the oxide dispersion state in the cross section of the wire produced by internal oxidation of the silver alloy wire is caused by the following reasons.

That is, when a silver solid solution alloy wire of radius R and solute concentration NM(o) is heated in an atmosphere of oxygen pressure Po, the thickness of the internal oxidation layer after t hours is R-r as shown in FIG. It is given by formula '11. N here.

S is the oxygen concentration on the wire surface, which is proportional to Po, and Do
is the diffusion coefficient of oxygen in the alloy, and n is a constant determined by the type of oxide produced. Therefore, the oxidation rate at position r in all directions of the line village is expressed by the equation '2' and is not constant. It is known that the higher the oxidation rate, the finer the oxide particles generated by internal oxidation, and the slower the oxidation rate, the coarser the oxide particles become.

As a result, the coarsest oxide is dispersed at the r31/station, and the extremely fine oxide is dispersed at the center.

Figure 2 a shows the Ag-15%Cd alloy wire of Niyanagi ◇ at 750°C.
This is the hardness distribution in the cross section of an Ag alloy wire heated in air and internally oxidized, and the hardness is the lowest at r3R/3.

Although the fine oxide in the center is useful for hardening the material, it is often undesirable for contact performance.

The present invention has solved the above problems by the method described below.

As shown in FIG. 3, a solid solution powder of silver and oxide-forming elements and an oxide powder are mixed, molded, or further scaled to form a cylindrical metal body 1, which is then melted and cast or further cut. It is inserted into a cylindrical metal body 2 made of the prepared solid solution of silver and oxide-forming elements to form a composite body 3.

The purpose of the method of the present invention is to make a substantially homogeneous wire rod by keeping the oxide content constant in the core and the outer shell and controlling the particle size, so the composition of the solid melt powder is ,
After mixing the oxides, the average concentration of the oxide constituent elements is made equal to the concentration of the oxide constituent elements in the solid solution constituting the outer shell.

Within this range, the mixing ratio of the oxides may be arbitrarily selected, but it is preferably 10 Vol% or less. 10V
This is because if it exceeds ol%, the strength of the core will be insufficient in the wire drawing described below, and it will be difficult to form it into a predetermined size.

However, if, for example, swaging is performed without performing a tie line, the lack of strength of the core is not so much of a problem.

On the other hand, the lower limit of the mixing ratio of the oxide powder is limited by the amount ultimately dispersed, but it is preferably 0.5% or more in order to achieve a sufficient effect. The composite is subjected to plastic working such as extrusion, forging, swaging, or wire drawing to form a wire rod in FIG. 3b.

Since the wire is to be internally oxidized, it is preferable to make it smaller than the 5th side, but this restriction is not strict and can be applied to even thicker wires. The radius rc of the cylindrical metal body of the core with respect to the radius Rc of the composite body is 0 rc and Rc
/2. This is because if rc exceeds Rc/2, the characteristics of the material obtained by substantially internally oxidizing the cylindrical metal body will be significantly changed.

As rc increases, plastic workability decreases, so
Preferably, rc<Rc/3. Oxidize the wire at a temperature and oxygen pressure suitable for obtaining the desired oxide particle size,
A silver alloy wire with oxide dispersed therein.

The oxidation temperature is preferably 600q0 or more and 850q0 or less.

At lower temperatures, agglomerated oxides may form along the crystal grains of the outer shell metal body, and cracks may occur during internal oxidation. If it exceeds 850 oo, the produced oxide becomes extremely coarse and may not be suitable as a contact material.

Preferably, the oxygen pressure is 0.21 atm or higher. 0
．． If the pressure is less than 2 atmospheres, the same problems as in the case where the oxidation temperature is extremely low will occur.

The oxidation conditions may be constant from the beginning to the end of the oxidation, or may be changed during the oxidation, for example, when the oxidation of the outer shell metal body is completed. As the oxide-forming element, for example, cadmium is used.

Material non-uniformity between the center and the outer shell caused by internal oxidation becomes more pronounced as the concentration of oxide-forming elements increases, but cadmium can be contained in silver in an amount of 15% or more, and material non-uniformity is likely to occur. The oxide-forming elements may contain up to 10% of other additives that control the morphology, particle size, and dispersion of the oxide.

The method of the present invention essentially consists in controlling the morphology and particle size distribution state of the oxide.

Representative additives include silver, antimony, and indium. The amount of additives is limited to 10% or less because if it exceeds 10%, it not only controls the morphology, particle size, and dispersion state of the oxide, but also changes the quality of the oxide.

The diameter of the oxide powder is 0.5 mm or more and 5 mm or less.

The method of the present invention improves the abnormal refinement of oxides generated in the center due to internal oxidation, so 0.
If it is less than 5 mm, the purpose cannot be achieved, while if it exceeds 5 mm, it becomes difficult to provide sufficient contact performance. As shown in FIG. 4, in the obtained silver alloy wire, the oxide 3 mixed as oxide powder and the oxide 4 generated by internal oxidation are dispersed in the core part 2, and the inner part is dispersed in the outer shell part 5. Only the oxide 4 produced by oxidation is dispersed. By header processing the alloy wire manufactured by the method of the present invention, it becomes possible to manufacture rivet-type composite contacts a and disc-shaped contacts b as shown in FIG. 5 continuously and in good order. Not only will the range of use of this alloy be expanded, but it can also be expected to improve productivity.

Examples are shown below.

Example 1 A cylindrical metal body with a wall thickness of 25 mm, an outer diameter of 7 W, and a length of 10 mm was made of a silver-15 M% cadmium alloy. After mixing 4.5wt% of cadmium oxide powder with an average particle size of 2.5 degrees to cadmium alloy powder and molding it at n/m of 4,
A cylindrical composite body phosphorized in nitrogen at 00qo was inserted into the cylindrical metal body, heated at 800° C. in nitrogen, and then hot extruded at an extrusion ratio of 1:20.

The extruded material was drawn in the cold while being dulled in the middle to obtain a two-way wire rod. The core portion in which cadmium oxide was dispersed in the cross section of the wire was approximately 0.6 mm. The wire was internally oxidized by heating in air at 75 mm. The hardness distribution of the obtained alloy wire is shown in FIG. 2b. According to the method of the invention detailed above,
By appropriately selecting the particle size of the oxide powder, the mixing ratio, and the internal oxidation conditions, it is possible to obtain a silver alloy wire with stable contact performance in cross section as well as apparent properties such as hardness.

Furthermore, since the concentration of the solute to be oxidized is reduced in the core, the oxidation time can be shortened, as is clear from equation {1}. Example 2 Made of silver, 15M% cadmium, and IM% tin, the outer diameter of the wall thickness of 25 mm is 7 mm. A cylindrical metal body with a length of 100 arms was made, and a Ginichi 1 mark K of 25 skins or less was created using the gossip method.
%-/% tin alloy powder was mixed with 4.5% of cadmium oxide powder having an average particle size of 2.5A, molded at 4 tons/second, and then sintered at 700 qo in nitrogen.

The cylindrical late compact was inserted into the cylindrical metal body, heated at 800° C. in nitrogen, and then hot extruded at an extrusion ratio of 1:20.
The extruded material was cold-drawn into a wire rod with two ribs ◇ while being intermediately annealed. The core portion in which cadmium oxide was dispersed in the cross section of the wire had a width of 0.6. The wire was heated in air at 750° C. to internally oxidize it. The hardness distribution of the obtained alloy wire is shown in FIG. 2c. Experimental Example 1 A two-walled wire rod of Ag-15wt% cadmium alloy was prepared and heated at 75,000 in air and 1 atm in oxygen to internally oxidize it to the center.

The hardness distribution of the obtained wire is shown in Figure 1a. The center part had fine oxides dispersed in each case and had a different texture from the outer shell part.

Example 3 Using the alloy wire obtained in Example 1, a composite contact with four sides as shown in FIG. 5a was manufactured by header processing.

As shown in Figure 4, the cross-sectional assembly of the composite contact was significantly different between the outer shell part 1 and the center part 2, but in the ASTM test (100V
．． 30A) Results As shown in Figure 6, the number of openings and closings and the amount of wear were shown, and the contact surface portion after the test was smooth. Example 4 The composite support point produced according to Example 3 was heated to 220V. A cutoff test (0 test) was conducted on 125 ships.

The amount of wear due to three operations was less than 15 days/1 pair, and the surface was smooth.

Experimental Example 2 Using the alloy wire manufactured in Experimental Example 1, a composite contact similar to that in Example 3 was manufactured, and a 220V. 12
A cut-off test was conducted at 50A.

The average amount of wear due to three activations was 4 enemies per pair.

After the test, the center of the contact was concave.

[Brief explanation of drawings]

FIG. 1 shows a cross section of the wire during internal oxidation. Figure 2 shows the hardness distribution of the wire rod in the opposite direction, a is obtained by the manufacturing method of the secondary method, b and c are the hardness distribution of the wire rod manufactured by the method of the present invention, and Figure 3 is the hardness distribution of the wire rod manufactured by the method of the present invention. A composite and b wire. 1 is a cylindrical metal body, 2 is a cylindrical metal body, and 3 is a composite body. FIG. 4 is a schematic cross-sectional view of an alloy wire obtained by the method of the present invention, in which 2 is a core, 5 is an outer shell, and 3 and 4 are oxides. FIG. 5 is a cross section of a pet-type composite contact and a disc-shaped contact b manufactured using the alloy wire obtained by the method of the present invention. 1 is the outer shell portion, and 2 is the center portion. FIG. 6 shows the relationship between the number of openings and closings and the amount of wear as determined by the ASTM test. Talent! 2 figures, 3 figures, 4 figures, 5 figures, 6 figures

Claims (1)

[Scope of Claims] 1. In the production of a silver alloy wire in which oxides are dispersed, a cylindrical outer shell portion containing an oxide-forming element as a solid solution, a silver alloy powder and an oxide containing fewer oxide constituent elements than the outer shell portion. A cylindrical composite is formed from a cylindrical core formed by mixing, molding, or further sintering the powder, and after forming a silver-oxide alloy wire coated with a silver alloy by hot working or cold working, the wire is heated with air. 1. A method for producing an oxide-dispersed silver alloy wire, the method comprising heating and oxidizing it in oxygen or oxygen or a combination thereof to obtain a silver-oxide alloy wire. 2 The cylindrical core is 7/100 or more and 1/3 of the diameter of the composite.
A method for manufacturing an oxide-dispersed silver alloy wire according to claim 1, which is as follows. 3. The method for producing an oxide-dispersed silver alloy wire according to claim 1 or 2, wherein the mixing ratio of the oxide is 0.5% or more and 10 Vol% or less. 4. The method for manufacturing an oxide-dispersed silver alloy wire according to claim 1, 2, or 3, wherein the diameter of the oxide is 0.5 μ or more and 5 μ or less. 5. The method for producing an oxide-dispersed silver alloy wire according to claim 1, 2, 3, or 4, wherein the oxide powder is cadmium oxide. 6. The method for producing an oxide-dispersed silver alloy wire according to claim 1, 2, 3, 4, or 5, wherein the silver alloy powder is a spray powder. 7. The method for producing an oxide-dispersed silver alloy wire according to claim 1, 2, 3, or 6, wherein the oxide-forming element is cadmium. 8. A method for producing an oxide-dispersed silver alloy wire according to claim 1, 2, 3, or 6, wherein the oxide-forming element contains 10% or less of tin, antimony, or indium. .