JPH09118943A - Oxygen free copper alloy for vacuum device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silver-zirconium oxygen free copper alloy optimum as the structural material for vacuum devices having an excellent softening temp. characteristic and little gas discharge. SOLUTION: This oxygen free copper alloy is composed of, by wt. <=0.001% oxygen, 0.01-1% silver or 0.005-0.5% zirconium and the balance <=0.02% impurities. This alloy is used as the optimum material for constructing vacuum devices such as a cooling channel 1 of a beam duct and a beam channel 2 or a pump channel 3 or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxygen-free copper alloy used as a constituent material of various vacuum devices such as a vacuum beam duct for particle accelerators and an acceleration cavity, and more particularly, it is particularly important for constituent materials of these vacuum devices. The present invention relates to an oxygen-free copper alloy having high softening temperature characteristics and low gas releasing characteristics.

[0002]

2. Description of the Related Art For example, as a beam duct of a storage ring used for the purpose of accumulating particles, a duct as shown in FIG. 5 is known. This duct is composed of a cooling channel 1, a beam channel 2 and a pump channel 3, and in many cases aluminum or aluminum alloy is used as its constituent material. Since aluminum-based metals have considerably high thermal conductivity and, above all, have excellent extrudability, they are optimal as materials for ducts of this type with complicated shapes. This material has been used as the mainstream of beam duct components.

However, since the accelerators in recent years are becoming more and more energetic, the radiant light generated by the accelerators is naturally strengthened accordingly, and the heat load on the beam duct is significantly increased. However, the construction of the beam duct with aluminum-based metal has reached the limit in terms of thermal conductivity and mechanical strength for efficiently eliminating generated heat, and therefore, how to deal with this heat load. This is a very important issue for these types of beams. The most effective measure to solve this problem is considered to be the utilization of oxygen-free copper.

As is well known, copper has about twice the thermal conductivity and mechanical strength of aluminum, and oxygen-free copper, as its name implies, has an extremely high oxygen content compared to ordinary tough pitch copper. Since it is very small, the amount of contained gas is naturally small, so it can be said that it is an optimum material as a constituent material of a vacuum device which does not like to release gas from constituent materials. This is, for example, “Proceeding of the 8th Me
et-ing on Ultra Vacuum Tec
hnies for Accelerators
and Storage Rigs (KEK Pro
ceedings 92-4). P. 213 (19
92) ”, and it is clear that oxygen-free copper will be frequently used as a constituent material of this kind of high vacuum device in the future.

By the way, when it is considered to apply oxygen-free copper as a constituent material of a beam duct as shown in FIG. 5, it is difficult to adopt an extrusion method for this.
As is well known, oxygen-free copper does not have a good hot-extrudability like aluminum, and therefore, in order to manufacture a duct having a complicated shape as shown in FIG. There is no choice but to depend on the bonding method of channels 1, 2, and 3. That is, first, the cooling channel 1, the beam channel 2, and the pump channel 3 are independently molded by cold working from a blank tube of oxygen-free copper, and then the channels 1, 2 thus obtained, A method of forming a predetermined beam duct by joining and integrating 3 at the joining portion will be adopted.

In this system, the channels 1, 2 and 3 are much improved in mechanical strength in the process of cold working, so that they are more suitable for this kind of use than hot working. However, on the other hand, the influence of heat when joining the joining portion 4 comes up as one big problem. As the joining means for the joining portion, electron beam welding is adopted, which is said to have a local heat input among various joining methods, and therefore a small thermal strain is applied to the welding target, but in reality, this method is used. It has been confirmed from experience that it is difficult to eliminate the influence of heat at the time of welding without actually harming even with the joining method.

[0007]

The effect of the joining heat of this joining portion appears as a softening of the radiated light direct irradiation portion, and according to the inventor's experiment, the Vickers hardness of this direct irradiation portion which should be away from the joining portion. Has been confirmed to decrease to about 50 to 60, which suggests that the temperature of the relevant part has risen to about 300 to 350 ° C. Softening means a decrease in the mechanical strength of the relevant part, but alloying oxygen-free copper is effective as a measure against the problem of thermal softening, and the additive element for this alloying is effective. For this, silver or zirconium is particularly effective. It can be said that both of these elements are ideal elements that have the property of increasing the softening temperature without impairing the good thermal conductivity of oxygen-free copper, and at the same time improving the mechanical strength,
It is an extremely significant element in constructing an oxygen-free copper beam duct so as to withstand a higher heat load.

By the way, although the above-mentioned device such as the beam duct is used under an extremely high vacuum, one characteristic required for the constituent materials of these ultra-vacuum devices is low gas emission. This property is necessary for maintaining the performance of the accelerator, and when using a material that emits a lot of gas,
The performance of the accelerator is greatly deteriorated by scattering particles to be accelerated in the beam duct or causing electric discharge. For this reason, it is necessary to use a material that emits little gas as a material for forming the duct. In this sense, oxygen-free copper is the optimum material, as described above.
This is even compared to tough-pitch copper and the like, and it cannot be said that the present gas release level of oxygen-free copper is satisfactory for this type of vacuum device, which is required to have higher performance in the future.

One of the reasons why oxygen-free copper has a gas releasing property is that although the molten metal in melting / casting is shielded from the atmosphere by the reducing gas coating, these processes are performed under atmospheric pressure. It is considered that hydrogen is likely to enter the molten metal under the influence of water vapor in the atmosphere and that hydrogen gas and the like remain as residual gas in oxygen-free copper.

An object of the present invention is to provide a silver-zirconium-based oxygen-free copper alloy which has excellent softening temperature characteristics and a small amount of gas emission, and is therefore optimum as a constituent material of a vacuum apparatus.

[0011]

In order to achieve the above object, the present invention provides an oxygen-free copper alloy in which at least one of silver and zirconium is added to oxygen-free copper having an oxygen concentration of 0.001% by weight or less, Oxygen-free for vacuum equipment, characterized in that the amount of silver added is 0.01 to 1% by weight, the amount of zirconium added is 0.005 to 0.5% by weight, and impurities are less than 0.02% by weight. A copper alloy is provided.

Silver and zirconium added for the purpose of increasing the softening temperature of oxygen-free copper in order to prevent the softening due to the welding heat of the joint, the higher the addition amount, the higher the softening temperature of oxygen-free copper. However, it has been confirmed in the course of the present invention that when the amount reaches a certain level, the softening temperature rises slowly even if it is added more, while the electrical conductivity decreases greatly. . Therefore, when considering such a tendency, it is important to set the addition amount of these elements within the optimum range. From this point, the addition amount of silver is 0.01 to 1% by weight, and zirconium is added. The addition amount of 0.005 to 0.5% by weight is an important constituent element in the present invention.

It has also been confirmed in the present invention that when impurities in the copper matrix are combined with both silver and zirconium additives, it adversely affects the softening temperature increasing action. Therefore, as the base oxygen-free copper, It is important to use oxygen-free copper in which the concentration of impurities other than the additive elements is less than 0.02% by weight and the concentration of oxygen is 0.01% by weight or less. It has been confirmed that it also acts as an indispensable factor for the configuration. The hydrogen content of the oxygen-free copper alloy for vacuum equipment manufactured by the present invention is preferably 0.5 ppm by weight or less, and this quantity is a more preferable level in order to cope with the sophistication of vacuum equipment. Can be said.

As a specific method for performing vacuum treatment on molten oxygen-free copper, for example, an oil rotary pump or mechanical booster pump used for vacuum exhaust is used. The degree depends on factors such as the vacuum treatment time, the surface area of the oxygen-free copper melt exposed to the vacuum, and the amount of the melt, but basically 10T
It is desirable to set it to or or less. The oxygen-free copper alloy of the present invention of the type characterized by subjecting the melt of the oxygen-free copper alloy to vacuum degassing treatment is used when the oxygen-free copper alloy containing silver and zirconium is used as a constituent material for a beam duct or the like. In addition, it is more practical in that the gas releasing property can be adjusted, and is also significant in that the effect of improving the plastic workability in the zirconium-containing non-copper alloy can be obtained.

That is, in the zirconium-containing oxygen-free copper alloy, since zirconium is a chemically active substance, it is easy to form zirconium oxide when it is added to oxygen-free copper. The presence of the substance adversely affects the plastic workability and may cause a defective phenomenon such as cracking at the time of extrusion molding, but the vacuum degassing treatment in the present invention acts to prevent the formation of this oxide. Therefore, as a result, a secondary effect that the problem of plastic workability, which was a problem for the zirconium-containing oxygen-free copper alloy, can be effectively solved is brought about. The vacuum degassing treatment for the oxygen-free copper melt is performed at the same time when the additives are added to the oxygen-free copper melt in the sense that the gas components contained in the silver or zirconium additive itself are also excluded. Alternatively, it is desirable to perform after addition.

By setting the amount of impurities to a specific elucidated level and further setting the addition amounts of silver and zirconium within the optimum range, a vacuum device having a low gas releasing property and a high softening temperature can be obtained. An oxygen-free copper alloy for components is provided.

[0017]

1 shows a beam duct of oxygen-free copper alloy, which has a cooling channel 1, a beam channel 2 and a pump channel 3, each channel being joined by a joint 4 and a beam channel 2. The radiated light direct-radiation unit 5 is located on the inner wall. As an example of oxygen-free copper alloy,
By performing vacuum treatment in a continuous casting furnace, a silver-containing oxygen-free copper alloy having an oxygen concentration of 0.001 wt% or less and impurities of less than 0.02 wt% was manufactured. As the vacuum processing apparatus, the same vacuum degassing apparatus as shown in Japanese Patent Application No. 60-61667 is used, and the degree of vacuum is 0.3 to 0.5 Torr.
The vacuum treatment was performed under the condition that the vacuum treatment time was 3 minutes. The addition of silver to the oxygen-free copper was carried out by continuously feeding a pure silver wire into the oxygen-free copper melt at a constant rate in a holding furnace provided immediately before the mold. In the cast ingot (diameter 200 mm) of the oxygen-free copper alloy produced as described above, the silver content was 0.21% by weight and the hydrogen content concentration was 0.3 ppm by weight (Example 1).

In addition, the manufacturing is carried out in two cases, that is, when the vacuum treatment is stopped in the above embodiment (Example 2) and when both the vacuum treatment and the addition of pure silver wire are stopped (Comparative Example 1). , Produced each ingot. Among these, the former hydrogen content was 0.8 weight ppm. Next, a tube having an outer diameter of 140 mm and a wall thickness of 15 mm is made from each ingot manufactured as described above by a hot extruder, and subsequently cold drawn to give an outer diameter of 117 mm and a wall thickness of 7.5 mm. Of the cold-worked material (cold-working degree of 56%), and then by subjecting this worked material to a drawing process, a beam channel 2 having a size and shape as shown in FIG. A blank tube was manufactured.

With respect to the other components, that is, the cooling channel 1 and the pump channel 3, the element pipes are manufactured through the same procedure, and finally, the joint portion 4 between the element pipes of the channels 1, 2, 3 is formed. A predetermined beam duct was manufactured by welding with electron beam welding. As a result of investigating the softening temperature of the elementary tube of the beam channel 2 when the heating time was set to 1 minute, the sample prepared from the silver-containing oxygen-free copper alloy of this example (Examples 1 and 2) was vacuum treated. The softening temperature of the raw tube made from the ingot of Comparative Example 1 without addition of silver was 260 ° C, showing a softening temperature of 420 ° C regardless of the presence or absence of the above. It was It is estimated that the raw tube made of the silver-containing oxygen-free copper alloy of this embodiment can handle a heat input of 75 KW / m. Further, the measured Vickers hardness of the radiant light direct-irradiation part 5 of the beam duct made of the silver-containing oxygen-free copper alloy (Examples 1 and 2) was 95 to 100, and no softening was observed in any of them.

Vacuum treatment was performed in the same manner as in Example 1 to produce an ingot made of a zirconium-containing oxygen-free copper alloy having an oxygen concentration of 0.001% by weight or less and impurities of less than 0.02% by weight, and a predetermined beam was produced from this ingot. I made a duct. This example is different from Example 1 described above in that the mother alloy was used when zirconium was added to the melt of oxygen-free copper and that the saturated vapor pressure of zirconium was lower than that of silver during vacuum treatment. The evaporation loss is so small that it can be neglected. Therefore, there are two points in consideration of this point when setting the addition amount. The zirconium content of the obtained oxygen-free copper alloy was 0.02% by weight, and the hydrogen concentration was 0.4% by weight (Example 3). In addition, without vacuum treatment, Example 3
An oxygen-free copper alloy ingot containing the same amount of zirconium (Example 4) and an ingot not subjected to zirconium addition treatment or vacuum treatment (Comparative Example 2) were also manufactured. The hydrogen concentration in Example 4 was 1.0 ppm by weight.
Met.

Similar to the first embodiment, the softening temperature measured for the tube of the beam channel 2 is 600 in the third and fourth embodiments.
The temperature was as high as ° C, and it was possible to confirm a higher level of softening temperature than that in the case of adding silver. Further, the Vickers hardness of the radiated light direct-irradiation part 5 after the electron beam welding of the beam ducts manufactured from these Examples 3 and 4 is 110-1.
It was 20 and it was confirmed that all of them had sufficient hardness. Next, the results of gas release measurement performed on each of the beam ducts manufactured according to the above examples will be described.

First, 20 mm × 80 mm test pieces were taken from each beam duct of Examples 1 to 4 and subjected to ultrasonic cleaning degreasing in acetone, and then pickled with dilute nitric acid and washed with pure water. After further drying with hot air, this was placed in a test apparatus as shown in FIG. In FIG. 2, 6 is a test piece, 7 is a transparent quartz chamber for containing the test piece, 8 is an infrared heater provided around the chamber 7, and 9 is a heater.
Indicates a gas analysis chamber. The test piece 6 is heated from room temperature to 8 at a heating rate of 20 ° C./min by the radiant heat from the heater 8.
The amount of gas that is heated to 00 ° C and released at a predetermined temperature is the gas release rate q (Torr · L / sec /
It is understood as cm2). The gas release rate q was calculated by the following method called the slew butt method.

That is, the gas released from the test piece having the surface area A (cm 2) at the release rate Q (Torr · L / sec 9) per second is exhausted by the turbo molecular pump 10, but the orifice 11 provided on the way is used. When passing, a differential pressure is generated before and after Elyphis 11. This generated differential pressure P1−
P2 (Torr) is measured by two vacuum gauges 12 and 12, and the gas release rate q is calculated from the conductance C (L / s) of the orifice based on the formula Q = C (P1-P2) = qA. Then, it was confirmed that all of Examples 1 to 4 had a small gas releasing property. The graphs of FIG. 3 and FIG. 4 are comparisons of the difference in the gas release rate between the case where the vacuum degassing treatment, which is one type of the present invention, is performed and the case where it is not performed. The graph of FIG. 3 shows the results of measurement and calculation for test pieces taken from a beam duct made of a silver-containing oxygen-free copper alloy, and ● indicates Example 1 and ○ indicates Example 2, respectively.

Similarly, FIG. 4 shows the measurement and calculation results in the case of a zirconium-containing oxygen-free copper alloy, where Δ indicates Example 3 and
X shows Example 4. In any of the graphs, it was observed that Examples 1 and 2 in which the oxygen-free copper alloy in the molten state was subjected to the vacuum treatment had a significantly lower gas release rate than Examples 3 and 4 in which the vacuum treatment was not performed. Shows that the oxygen-free copper alloy obtained by performing the vacuum degassing treatment is more practical as a constituent material for a vacuum device.

[0025]

As described above, according to the oxygen-free copper alloy for a vacuum apparatus of the present invention, the oxygen concentration is set to 0.001% by weight or less, and the addition amount of silver is set to 0.01 to 1% by weight. Either set or the amount of zirconium added is 0.005 to 0.
As a result of setting the content to 5% by weight and simultaneously setting the impurities to less than 0.02% by weight, it is possible to provide an optimum oxygen-free copper alloy as a constituent material for a vacuum device having a high softening temperature and less gas emission, It is also possible to provide an oxygen-free copper alloy in which this gas releasing property is adjusted to a lower level by performing vacuum degassing treatment under a molten state,
In applying oxygen-free copper as a constituent material of a vacuum device such as a beam duct, the effect of the present invention is extremely large.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an oxygen-free copper beam duct.

FIG. 2 is an explanatory view of a test apparatus for measuring a gas release rate.

FIG. 3 is a gas release rate in Examples 1 and 2 for a silver-containing oxygen-free copper alloy.

FIG. 4 shows gas release rates in Examples 3 and 4 targeting a zirconium-containing oxygen-free copper alloy.

FIG. 5 is an explanatory view of a conventional aluminum beam duct.

[Explanation of symbols]

 1 Cooling channel 3 Pump channel 5 Direct radiation part 2 Beam channel 4 Junction part

Claims (3)

[Claims] 1. An oxygen-free copper alloy in which at least one of silver and zirconium is added to oxygen-free copper having an oxygen concentration of 0.001% by weight or less, and the amount of silver added is 0.01 to 1% by weight. An oxygen-free copper alloy for a vacuum device, characterized in that the amount added is 0.005 to 0.5% by weight and the amount of impurities is less than 0.02%. 2. The oxygen-free copper alloy for a vacuum apparatus according to claim 1, wherein the impurities include hydrogen in an amount of 0.5 ppm by weight or less. 3. The oxygen-free for a vacuum apparatus according to claim 1, wherein the concentration of the impurities is adjusted by subjecting the oxygen-free copper alloy to a vacuum degassing treatment under a low-pressure atmosphere of 10 Torr or less in a molten state. Copper alloy.