JPS61227330A - Manufacture of contact material for vacuum valve - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a method of manufacturing a contact material for a vacuum valve using a Cu-Cr alloy and a CLJ-Ti alloy.

[Technical background of the invention and its problems]

The properties required for contact materials for vacuum valves include three basic requirements: welding resistance, withstand voltage, and cutoff performance, and other important requirements include low and stable temperature rise and contact resistance. It has become. However, since some of these requirements are contradictory, it is impossible to satisfy all requirements with a single metal species.

For this reason, in many contact materials in practical use,
Contact materials have been developed that combine two or more elements that mutually compensate for the lack of performance, and that are suitable for specific applications such as large current or high voltage applications, and have reasonably excellent properties. However, the reality is that a contact material for vacuum valves that fully satisfies the ever-increasing demands for higher withstand voltages and larger currents has not yet been obtained.

For example, Cu-B containing a welding prevention component such as B1 in an amount of 5% or less is used as a contact material aimed at increasing current.
1 alloy is known (Japanese Patent Publication No. 41-12131), but because the solubility of 3i in the Cu matrix is extremely low, segregation often occurs, and the surface roughness after interruption is large.
It has problems such as difficulty in processing and molding. Also,
A Cu-7e alloy is also known as another contact material aimed at increasing current (Japanese Patent Publication No. 44-23751).

Although this alloy alleviates the above-mentioned problems of the CLJ-Bi alloy, it is more sensitive to the atmosphere than the Cu-13i alloy and therefore lacks stability in terms of contact resistance and the like.

Furthermore, a common feature of these contacts such as Cu-Te and Cu-3i is that they have excellent welding resistance, but even if their withstand voltage characteristics are sufficient for application to the conventional medium voltage class, It has become clear that this method is not always satisfactory for applications in the field of high voltages.

On the other hand, a sintered alloy of Cr and a highly conductive component such as Cu (or AU>) is known as a contact material intended for high voltage resistance.However, since Cr is a metal that is extremely easily oxidized, powder or It goes without saying that controlling the compact is important, but the atmospheric conditions during pre-sintering and infiltration also affect the material properties.For example, the temperature and time during pre-sintering and infiltration must be adequately controlled. The reality is that even the CU-Cr alloys obtained by this process have variations and instability in contact resistance or temperature rise characteristics, and a stable product that eliminates these variations is desired.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a contact material for a vacuum valve that can stabilize contact resistance characteristics and temperature rise characteristics.

[Summary of the invention]

The present invention provides a cooling rate for a vacuum valve material in the cooling process after the sintering and infiltration process, in which the cooling rate during a predetermined temperature difference in the cooling temperature range of the cooling process is determined by the temperature rise characteristic of the vacuum valve material. cooling means for cooling the vacuum valve material at a predetermined temperature in the cooling temperature range for a period of time to increase the conductivity of the material for the vacuum valve; and a reheating means for reheating the vacuum valve material at a predetermined reheating temperature within the cooling temperature range, and at least one of these means is provided to produce the vacuum valve material. This is a method of manufacturing the material.

[Embodiments of the invention]

Hereinafter, a method for manufacturing a contact material for a vacuum valve according to the present invention will be explained. Before specifically explaining the embodiments, the process leading up to the present invention will be briefly explained.

According to research, the above-mentioned instability of CLJ-Cr-based contact materials is caused by: (1) compositional fluctuations in the Cu-Cr alloy, (2) Or powder particle size, particle size distribution, degree of segregation, and (2) vacancies present in the alloy. It was found that it depends on the degree of It was acknowledged that these solutions were effective through the selection of the raw material Cr and the management of the sintering technology, but in order to further improve the maintenance of stability, more detailed measures should be taken in addition to the above ■, ■, and ■. It was found that proper management of sintering technology was required. That is, it has been found that the instability of the above-mentioned properties is correlated with a slight difference in the amount of Cr contained in Cu. In other words, when estimating the amount of Or contained in the CLJ part in the cu-Cr alloy using the decision quantity method using X-ray microanalysis, the Qu-Qr gold alloy, which showed unstable values in the above-mentioned properties, is generally 0.5~ Q, 2wt
% of the Cu-Cr alloy that exhibits stable characteristics using the technology of the present invention, which will be described later.
The typical value was 0.1% or less.

It is recognized that this difference depends on the thermal history of the Cu-Qr gold alloy, especially after sintering or infiltration, and by carefully controlling these conditions, it is possible to improve the electrical conductivity of the Cu-Cr gold alloy and reduce its dispersion width. It was revealed that the effect was large. Note that the thermal history after sintering or infiltration referred to herein can be represented by the cooling rate characteristic substantially experienced by the contact point itself. In other words, it refers to controlling the cooling rate, which varies depending on the size of the contact and the characteristics of the furnace, to a predetermined condition.

The present inventors have confirmed that, as a method for alleviating such undesirable characteristics, it is effective to improve the electrical conductivity characteristics of the material and to reduce the variation thereof. That is, in the manufacturing process of the Cu-Cr contact alloy, it has been found that it is preferable to minimize the intrusion of Or in the CU center and to reduce the variation in the amount of intrusion between the contacts.

Next, the manufacturing method of the present invention will be specifically explained.

The raw materials used in the present invention are an arc-resistant material made of Cr and/or Ti powder that has been sufficiently degassed and whose surface has been cleaned, and a conductive material made of Cu and/or Ag. The material is made of In addition,
These Or, Ti.

In addition to Cu and AQ, approximately 10% or less of Te is added depending on the contact application.
, Bi, Sb, etc., welding resistant materials, W, MO.

An arc-resistant material such as V may be added as an auxiliary component. C
If the particle size of r, l”i exceeds 250 μm, pure Cu, A
The probability of contact between the Q parts increases, which is undesirable in terms of welding problems, but there is no lower limit to the particle size for the method of the present invention to exhibit its effects, and rather the activity increases. etc. will be determined based on handling.

Further, the heating conditions for obtaining the contact alloy were Cu.

By applying the conditions according to the method of the present invention in the cooling process or after cooling, both the method of completing the process below the melting point of Ag and the method of heating above the melting point of CU and AQ and infiltrating it. be effective. The latter method, which has a high diffusion rate, makes a large contribution to the contacts obtained.

On the other hand, the skeleton is made of only Cu and Ti, and a small amount of Qu is added to Cr and Ti in advance.

Regardless of the skeleton containing Ag, the same effects can be obtained by applying the conditions of the present invention.

Note that the contact resistance characteristics and temperature rise characteristics in the present invention are determined as follows. The contact resistance characteristics were determined by placing a flat electrode with a diameter of 201M and a surface roughness of 5μm facing a convex electrode with a radius of curvature of 100R and having the same surface roughness, and installing both electrodes in a 104Torr vacuum container with an opening/closing mechanism. Apply a load of 3 to . and both electrodes 1
The contact resistance is determined from the potential effect when 0A alternating current is applied. Note that the contact resistance value is a value that includes the resistance or contact resistance of wiring materials, switches, measuring instruments, etc. that constitute the measurement circuit as a circuit constant.

On the other hand, the temperature rise characteristic was determined by placing electrodes facing each other under the same electrode conditions as above and using a contact force of 3 in a vacuum chamber at 10'5 Torr.
0 J, open and close a current of 400 A 20 times with a separating force of 20 Ky, and apply a pre-opened diameter 1.5 AI11. Measurements were taken by inserting a thermocouple into a measurement hole with a depth of 41WI4. The temperature value is based on the ambient temperature of approximately 25℃.
This is a comparative value that also includes the influence of the heat capacity of the holder to which the electrode is attached. The numerical value is the number of samples: 3
This shows the maximum and minimum of .

Next, a first embodiment of the present invention will be described with reference to Table 1.

First, as a pre-process to which the manufacturing method of the present invention is applied, Cr with an average thickness of 125 μm is molded at a pressure of 2 tons/cd, and the molded body obtained is stored in a carbon container and heated at 1000°C in a vacuum.
Temporary sintering is performed for 1 hour. An infiltration material made of Qu is placed on the underside of this pre-sintered body, and the infiltration process is carried out under vacuum at 1200° C. for 1 hour. Next, after the infiltration process is completed, the contact alloy material is cooled from 1200°C.

Now, in this cooling process, the cooling temperature range is from 800℃ to 4℃.
The cooling rate is 0.0°C per minute between the predetermined temperature difference of 100°C.
It is cooled from 6°C to 6°C to reduce the temperature increase characteristics of Qu-Qr. Comparing the results of cooling using this method with the results of cooling under other conditions, we find that the cooling temperature range from 1200°C to 800°C is 3.
After cooling at 5°C/min, when cooling between 700°C and 500°C at a cooling rate of 80°C/min to 24°C/min, the temperature rise characteristics measured under the conditions described below rose to around 100°C. On the other hand, as in the present invention, the cooling rate is 60°C/min to 0.6°C.
It can be seen that when cooling at a rate of .degree. C./min (Effect Examples 1 and 2), the temperature rise characteristic is lower than the former at around 80.degree. C. and below. This tendency remains the same even if the cooling rate in the cooling temperature range of 800°C is significantly faster than 40°C/min (
Effect example 3.4). Further cooling from 1200°C to 800°C, and subsequent cooling between 700°C and 500°C (Effect Example 5)
However, since it shows an effective tendency, the cooling temperature range is 800℃.
This shows that it depends on the cooling rate passing through a temperature difference of 100°C arbitrarily selected between 400°C and 400°C. In addition, the contact resistance characteristics are in the group around 60 μΩ (effect examples 1 to 5).
) and 70 μΩ or more groups (Comparative Examples 1 and 2), which correspond to the temperature rise resistance. Note that when the cooling rate is slower than 0°6°C/min, productivity is poor.

Next, a second embodiment of the present invention will be described with reference to Table 2.

In this method, the vacuum valve material is heated and held at a predetermined temperature in the cooling temperature range of 800° C. to 400° C. for a period of time to increase the conductivity of the vacuum valve material, that is, 0.25 hours. Specifically, Cr having an average particle size of 74 μm is naturally filled into a carbon container, and pre-sintered in hydrogen at 900° C. for 1 hour. Cu containing 0.1% of 81 is on the upper side of this pre-sintered body.
After placing the infiltration material, the infiltration process is carried out in vacuum at 1150° C. for 1 hour. Next, the contact alloy material after the infiltration process is heated from 1150°C to each holding temperature at 13°3°C/
Cool at a rate of 1 minute.

After this cooling, the temperature rise characteristics and contact resistance characteristics of each contact piece were determined after being maintained for a predetermined period of time.

This is to show that the method of the present invention is the best. When the holding temperature is 1000°C as shown in Comparative Example 3,
The amount of solid solution of Cr in CLJ is large and the conductivity is 20-25%.
While the temperature is about lAC3, the holding temperature is 800°C as shown in Effect Examples 6 and 7.8.

At 600° C. and 400° C., the electrical conductivity increases to around 30% lAC3 or more, mainly due to a decrease in the amount of solid solution of Cr in the CLJ. In addition, as shown in Example 9.10, when considering the effect of holding time while keeping the holding temperature constant at 700°C, as shown in Effect Example 9.10, it is found that for 1 to 0.25 hours, it is close to 30% lAC3 or more. However, as shown in Comparative Example 4, at a holding time of 0.1 hour, the solid solution state of Cr in Cu is still maintained, so the conductivity is less than 30%lAC3. . The temperature rise characteristics also correspond to the difference in conductivity, with groups below 80°C (Examples 6 to 10) and groups above 90°C (Comparative Examples 3 to 4).
It is divided into Further, the contact resistance characteristics were similarly divided into a group of 60 μΩ or less (Examples 6 to 10) and a group of 70 μΩ or more.

If the holding temperature is lower than 400°C, it is not a good idea because a longer holding time is required.

Next, a third embodiment of the present invention will be described with reference to Table 3.

In this method, after the cooling process of the vacuum pulp material is completed, the material is reheated for at least 0.25 hours at a reheating temperature within the cooling temperature range of 400°C to 800°C. To explain specifically, a Cu lump was placed on top of Cu powder with an average particle size of 44 μm, and the whole was stored in a carbon container.
'After preliminary sintering at 950°C in vacuum for 3 hours, the temperature was raised to 125°C in vacuum without cooling, and infiltration work was performed for 1 hour. Next, it is cooled to room temperature at an average cooling rate of 24° C./min to obtain a contact material.

When this contact material was reheated from room temperature to each predetermined holding temperature as shown in Table 3, the reheating temperature exceeded 400°C8.
By reheating between 00°C and
What was about 6.0 to 30.9% lAC3 increased to around 40% lAC3 due to the precipitation of Cr from Cu (Examples 14 to 16). However, the reheating temperature is roughly 90
When the temperature was increased to 0.1000°C, the conductivity remained at around 30%lAC3 although it showed a slight increase (Comparative Examples 6-7
). In addition, as shown in Comparative Example 8, the reheating temperature was 200°C.
In this case, the transfer of Or from Cu was not yet sufficiently performed, and no effect was observed within the heating time of this experiment. As mentioned above, the above corresponds well to the amount of cr present in Cu. The temperature rise characteristics are divided into a group near 70°C or below and a group near 80°C or above,
Each corresponds to the behavior of conductivity. In addition, the contact resistance characteristics were also in the group around 50 μΩ (Examples 14 to 1).
6) and a group near or above 60 μΩ (Comparative Example 6)
~8), each corresponding to the conductivity behavior.

As shown in Effect Examples 11 and 12.13, if the holding time during reheating is 0.25 hours or more, the temperature rise characteristic will be around 70℃ or higher with a conductivity of 37% lAC3 or more.
Comparative example 5 maintains contact resistance characteristics of μΩ or less.
As shown in FIG.

From the above, it has been found that the properties can be improved by reheating treatment after cooling, but the temperature must be between 400'C and 800C and the holding time must be 0.25 hours or more.

Next, a fourth embodiment of the present invention will be described with reference to Table 4.

This manufacturing method adds a heating holding step and a reheating step to the vacuum valve material after the infiltration step. In other words, Cu powder with the same diameter as 149 μm Cr powder was
The mixture at a ratio of 5:5 was molded at 1.5 tons/ci, pre-sintered in vacuum at 1150°C, and then inserted into an alumina boat together with a CLJ alloy ingot containing 0°1% SB. Infiltration is carried out at 1200°C in vacuum. After this infiltration is completed, after cooling from 1200℃ to 800℃ at 24℃/min,
The cooling temperature range from 800°C to 600°C is further cooled to 600°C at a cooling rate of 3.5°C/min as in Effect Example 3. During this cooling, as shown in Effect Example 7, the holding temperature is 6.
When fabricated at 00°C, stable properties were obtained as shown in Effect Example 17. Thereafter, the above sample was cooled and then reheated at 500°C, but similarly stable characteristics were obtained (Example 18). From the above results, adjusting the cooling rate after the infiltration step to a predetermined condition and then superimposing the heating holding step and reheating treatment step was effective in further improving and stabilizing the properties. -As explained above, in the embodiment of the present invention, the cooling temperature range is from 800°C to 40°C.
Cooling rate 0.6 per minute between 100°C and the specified temperature difference of 0°C
Cooling means for cooling at ℃, at least 0.25 at any temperature in the cooling temperature range 800℃ to 400℃
Heating and holding means for heating and holding for a certain amount of time and cooling temperature zone f
QU- (::r) The temperature rise characteristics and contact resistance characteristics of the alloy can be improved, and the stability can also be improved.As a result, it is possible to satisfy all the characteristics required as a contact material for vacuum pulp, and is Contact materials can be obtained.

Note that the present invention is not limited to the above embodiments.

For example, even if part or all of Cu is replaced with Ag, the same effect as in the above embodiment can be achieved.

Further, part or all of Cr may be replaced with Ti.

In other words, the CLI, which corresponds to about 5%, is set to 74 μm in advance.
7i powder to obtain a molded body at 2.5 tons/d, pre-sintered in vacuum at 1100°C for 2 hours, placed Cu on top of the obtained skeleton, and sintered in vacuum at 1250°C for 1 hour. Perform infiltration work. When the temperature range from 700°C to 500°C in the cooling process after the infiltration process was cooled at a cooling rate of 3.5°C/min, the same area was cooled at a cooling rate of 24°C/min. The conductivity is 1.35 compared to the obtained Cu-Ti material.
An improvement of ~1.47 times was obtained.

As described above, similar to the above examples, an improvement in temperature characteristics was obtained corresponding to an improvement in electrical conductivity.

It has been found that the effects of the present invention can be applied to alloys with a very wide range of ratios of Cu (AO> and Cr (Ac).On the other hand, other characteristics of the contact material for vacuum valves, such as breaking In terms of performance, more than 90% Or (Ac
1> From the viewpoint of welding resistance, it is best to avoid alloys containing 90% or more of Cu (AQ).

〔Effect of the invention〕

As detailed above, according to the present invention, it is possible to provide a method for producing a contact material for vacuum pulp that can stabilize contact resistance characteristics and temperature rise characteristics.

Claims (1)

[Claims] 1) For the vacuum valve material in the cooling process after the sintering and infiltration process, the cooling rate during a predetermined temperature difference in the cooling temperature section of the cooling process is determined for the vacuum valve material. a cooling means that cools the vacuum valve material by setting it to a value that lowers the temperature rise characteristic of the vacuum valve; and reheating means for reheating the vacuum valve material at a predetermined reheating temperature within the cooling temperature range after the cooling process of the valve material is completed, and at least one of these means is provided to cool the vacuum valve material. A method for manufacturing a contact material for a vacuum valve, the method comprising manufacturing a contact material for a vacuum valve. (2) The cooling means has a cooling temperature range of 800°C to 400°C.
The method for manufacturing a contact material for a vacuum valve according to claim 1, wherein the predetermined temperature difference of 100°C is cooled at a cooling rate of 0.6°C to 6°C per minute. (3) The heating holding means has a cooling temperature range from 800°C to 40°C.
The method for producing a contact material for a vacuum valve according to claim 1, wherein the material is heated and maintained at a temperature of 0° C. for at least 0.25 hours. (4) The reheating means has a cooling temperature range of 400°C to 800°C.
The method for producing a contact material for a vacuum valve according to claim 1, wherein the method comprises reheating at a temperature of at least 0.25 hours.