JPS5948943B2 - conductive material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in conductive materials such as Ag-W and Cu-W. Conventionally, these types of conductive materials have been used, for example, in electrical discharge machining electrodes, air contacts, oil contacts, and SF.

It is used for various purposes such as gas contacts and vacuum contacts. Since this type of conductive material is used for applications that involve electric discharge, it is unavoidable that the conductive material gradually wears out and deforms due to the electric discharge, but it is necessary to use a material with as little wear and tear as possible. In addition, in order to reduce the resistance of the conductive material, a material with excellent contact and conductivity is required. In addition, electrodes for electrical discharge machining are said to have particularly good machining performance (machining speed, surface roughness). It is also necessary that the surface of the contact will not be oxidized due to temperature rise due to heating such as discharge during use, and that oxides will not be deposited thereon. Conventionally, from the viewpoint of electrical conductivity and consumability, Ag-W alloys or Cu-W alloys containing hard, high-melting-point W in Ag or Cu, which are highly conductive and thermally conductive, have been often used. For electrical discharge machining electrodes, it is desirable to have higher machining speeds and less wear and tear on the electrodes, and for contacts, materials with excellent electrical conductivity (current conductivity) are desired.

The present invention provides a material that further improves the performance of Ag-W or Cu-W, which is still insufficient.

The present invention focuses on the weight ratio of MO to W in Cu or Ag.
Contains 20 to 80% by weight of tungsten-molybdenum total solid solution (MOxWy) particles consisting of O/W = 0.005 to 10, 5 to 50% by weight of tungsten particles, and M
The total amount of OxWy solid solution particles and tungsten particles is 30
~90% by weight, and the iron group elements are O
The conductive material is made by dispersing it in an amount of up to 5% by weight.

Tungsten-molybdenum total solid solution particles 20-80
The material of the present invention, in which the tungsten particles are comprised in a proportion of 5 to 50% by weight, making up 30 to 90% by weight of the total amount, exhibits superior wear resistance during discharge, as shown in the examples below. As an electrical discharge machining electrode, it can reduce the amount of electrode wear and increase the machining speed of the workpiece, and as a contact, it maintains low wear and has good conductivity after opening and closing. It is possible to keep it low.

It has been found that the overall properties of electrodes, contacts, etc. of the material of the present invention can be significantly improved by co-adding appropriate amounts of tungsten-molybdenum solid solution, which has a low electronic work function, and tungsten, which has the highest heat resistance and arc resistance, as described above. It is something.

Electrical discharge machining generates excessive arc discharge between an electrode and the workpiece, the resulting thermal energy melts the electrode and the workpiece, and the melt is decomposed by thermal decomposition of the insulating oil by the arc. Blow it out with the generated high-pressure gas, and add it while repeating this process. It is something that carries out construction work.

Generally, the amount of wear of the electrode and the workpiece is expressed as amount of consumption=number of discharges x amount of consumption per discharge.

The consumption amount per discharge is said to be approximately proportional to the discharge energy per discharge, and is approximately determined by the circuit.

This discharge energy is distributed between the electrode (Wa) and the discharge electrode (We).
, is supplied to the workpiece (Wc). The tungsten-molybdenum solid solution, which is one of the constituent elements of the material of the present invention, is
As shown in Figure 1, it has a smaller work function than tungsten and is particularly effective as an electrode for electrical discharge machining, but since it has a lower melting point than tungsten, it is necessary to keep the arc wear of the electrode to a lower level. The enhancement of heat resistance and arc resistance by tungsten is extremely effective in the material of the present invention in combination with a tungsten-molybdenum solid solution.

Since the tungsten-molybdenum total solid solution has a smaller work function than tungsten, it increases the amount of electrons emitted from the electrode, and the energy of Wc in the discharge energy per discharge increases, while the energy of Wa decreases. In addition, since the amount of melting of the workpiece material is increased, and the electrode itself has sufficiently strengthened arc resistance by being composed of an appropriate amount of tungsten-molybdenum solid solution and tungsten, the amount of melting of the electrode is further reduced, making it easier to process. As speed increases, the rate of electrode wear is significantly reduced.

On the other hand, the material of the present invention also exhibits well-balanced performance at the contact point.

First, stabilization of conductivity (current conductivity) is estimated as follows. When opening and closing accompanied by an arc, especially in air, oxidation is further promoted due to exposure to high temperatures. As is well known, tungsten is WO2, WO2.7
2. It becomes an oxide such as WO3, and this tungsten oxide does not volatilize unless the temperature reaches a high temperature of 1100° C. or higher.

This is because the surface temperature of a contact with a small current capacity does not rise much, so as the number of openings and closings increases, a large amount of oxide remains on the surface and forms a film. Furthermore, this oxide reacts with copper or silver to form a stronger glass with a low melting point, which impedes electrical conductivity. On the other hand, MO undergoes an oxidation reaction under an arc, but these oxides
It volatilizes from 00℃, and the amount of volatilization is 10% of that of tungsten oxide.
It is 0 times or more. It is believed that the tungsten-molybdenum solid solution, which is one of the constituent elements of the material of the present invention, improves its electrical conductivity (current conductivity) because its oxidation properties are similar to molybdenum. Also tungsten
Lower melting point due to molybdenum solid solution content, i.e. heat resistance,
Tungsten compensates for the decrease in arc resistance and maintains contact wear at a sufficiently low level to provide well-balanced performance as a contact. The composition of the tungsten-molybdenum solid solution particles is preferably MO/W=0.005 to 10 by weight.

This is because when MO/W is less than 0.005, the work function value and oxidation resistance become equivalent to pure W, and the wear resistance and conductivity do not improve significantly. Also MO/W=10
If this is the case, although the conductivity (electrical conductivity) as a contact point is excellent, the melting point of the tungsten-molybdenum solid solution particles is lowered, the heat resistance is inferior, and the wear resistance is deteriorated, which is not preferable. For electrical discharge machining electrodes, the MO/W weight ratio is 0.
．． The MO/W weight ratio is particularly preferably in the range of 0.005 to 2.5, and for contacts, the MO/W weight ratio is particularly preferably in the range of 0.25 to 10. In the present invention, the amount of tungsten-molybdenum solid solution particles is 20 to 80% by weight, the amount of tungsten particles is 5 to 50% by weight, and the sum of the tungsten-molybdenum solid solution particles and tungsten particles is 30 to 90% by weight. Appropriate.

If the total amount is less than 30% by weight, the hardness of the conductive material decreases, heat resistance decreases, and wear resistance becomes inferior. If the total amount exceeds 90% by weight, the hardness improves but the conductivity decreases. The amount of heat generated by the arc can no longer be sufficiently conducted.
On the contrary, this is because the wear resistance deteriorates. The total amount of these tungsten-molybdenum solid solution particles and tungsten particles is preferably 50 to 80% by weight.

These conductive materials are manufactured using general powder metallurgical methods, but like tungsten, tungsten-molybdenum solution particles have poor wettability with silver or copper, do not have high density, and are easily formed by cavities. It is.

Iron group elements have the effect of improving this wetting, and are added to synthesize a sound alloy. However, if the amount is too large, the conductivity decreases, so it is necessary to keep it at 5% by weight or less. The effects of the present invention will be described below with reference to Examples.

Example 1 The weight ratio of M0 powder and W powder is MO/W=1.
A mixed powder consisting of 17 and 0.11 was dissolved in 28% aqueous ammonia.

This ammonium salt was gradually neutralized with hydrochloric acid to precipitate needle-shaped crystals. The co-precipitated WO3 and MOO3 were sintered in air at 800°C. This mixed powder was charged into a Ni boat, and the boat was covered with a lid and reduced at 1000° C. in an H2 stream to obtain a 4 μm alloy powder. When this powder was subjected to X-ray diffraction, it was found that each powder was a one-phase solid solution. This alloy powder, copper powder, silver powder, tungsten powder, and nickel powder were mixed in the proportions shown in Table 1, and after processing in a vibrating ball mill, a binder was added and a stamped body was created with a stamping force of about 3t0n/CIn2. After removing the binder at 700°C, copper and silver infiltration media were placed on top of each other to achieve the desired final composition shown in Table 1, and the temperature was 1000°C for silver and 1000°C for copper. Infiltration was performed in a hydrogen atmosphere at 1150° C. for about 2 hours to prepare alloy bodies.

This sintered body was cut into a size of 7 x 7 x 5 mm, and an electric discharge machine (D
-104BH) was used to conduct electrical discharge machining tests. The electrical discharge machining conditions were: machining zone molecule Ap2, machining fluid Nisseki Gene Oil jet pressure 0.2 kg/Cm, and workpiece material SKD-11. The shape of the workpiece was 13φ x 5φ x 20mm, and the processing time was 10 minutes. Further, for comparison, ordinary Cu-W was added and electrical discharge machining was performed under the same conditions. These results are shown in FIG.
It is clear that both processing speed and wear ratio are superior to conventional Cu-W. Furthermore, there was little wear on the corners of the electrode after processing, and the edges were sharp. Example 2 Sintered bodies 3 and 5 prepared in Example 1 were cut into predetermined shapes and brazed to a Cu base metal, and two types of tests were conducted under the conditions shown in Table 2.

Also, for comparison, general Ag-W (35Ag-65W)
and Cu-W (30Cu-70W) were added.

The conductivity test results are shown in Figure 3. The material of the present invention exhibits a voltage drop value that is about half that of the conventional material, and it is clear that the material has excellent conductivity when opened and closed many times. The results of the wear test are shown in the third
Shown in the table. The material of the present invention exhibited wear resistance that was higher than that of conventional materials. As described above, the conductive material of the present invention has excellent wear resistance and conductivity as an electrode and contact material, and is low in cost, so it has high industrial value.

[Brief explanation of the drawing]

Figure 1 shows the change in work function with respect to the MO/W ratio in a tungsten-molybdenum solid solution, Figure 2 shows the test results in Example 1, and Figure 3 shows the conductivity in Example 2. It is a figure showing a test result.

Claims (1)

[Claims] 1. Tungsten-molybdenum total solid solution (Mo_xW_y) particles with a weight ratio of molybdenum to tungsten (Mo/W) of 0.005 to 10 in copper or silver.
1. A conductive material comprising: 0 to 80% by weight, 5 to 50% by weight of tungsten particles dispersed therein, and the total of Mo_xW_y solid solution particles and tungsten particles being 30 to 90% by weight. 2. The conductive material for electrical discharge machining electrodes according to claim 1, having a Mo/W weight ratio of 0.005 to 2.5. 3. The conductive material for contacts according to claim 1, having a Mo/W weight ratio of 0.25 to 10. 4. The conductive material according to any one of claims 1 to 3, wherein the total content of the tungsten-molybdenum solid solution particles and the tungsten particles is 50 to 80% by weight. 5 Tungsten-molybdenum total solid solution (Mo_xW_y) particles with a weight ratio Mo/W of molybdenum to tungsten of 0.005 to 10 in copper or silver.
0 to 80% by weight, 5 to 50% by weight of tungsten particles are dispersed, and the total amount of Mo_xW_y solid solution particles and tungsten particles is 30 to 90% by weight, and 5% by weight or less of iron group elements. A conductive material characterized by containing. 6. The electrically conductive material for electrical discharge machining electrodes according to claim 5, having a Mo/W weight ratio of 0.005 to 2.5. 7. The conductive material for contacts according to claim 5, having a Mo/W weight ratio of 0.25 to 10. 8. The conductive material according to any one of claims 5 to 7, wherein the total content of tungsten-molybdenum solid solution particles and tungsten particles is 50 to 80% by weight.