JP3249650B2 - Copper alloy melting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for melting a copper alloy, and more particularly to a method for melting a copper alloy used as a material for electronic and electric equipment.
The present invention proposes a method of melting a copper alloy to advantageously produce a copper alloy such as Zr, Cu-Cr, or Cu-Ti.

[0002]

2. Description of the Related Art Generally, a copper alloy containing an active metal such as Zr is well known as a high-conductivity heat-resistant alloy.
For example, a master alloy of an active metal such as a Cu-Zr master alloy, a Cu-Cr master alloy or a Cu-Ti master alloy, and other necessary additives are added, and a high-frequency melting furnace or an electric furnace is used. In an active gas atmosphere or a reducing gas atmosphere,
Alternatively, it is produced by melting under a charcoal coating and then casting in most cases in the same conditioned atmosphere. (See JP-A-1-306534, JP-A-2-118057, and JP-A-2-173248)

In the conventional copper alloy production method described above, the addition of the active metal to the molten Cu in the furnace is performed by adding these metals or their mother alloys, for example, Cu-50% Zr, Cu-30% Zr.
Is directly injected into the molten Cu.

[0004]

Incidentally, when a Cu-Zr mother alloy is added in each of the above-mentioned prior arts, for example, a method for producing a copper alloy for terminals and connectors as disclosed in Japanese Patent Application Laid-Open No. 2-118057 is disclosed. ", The active metals to be added are Zr: 0.05-1.0 wt% and Cr: 0.1-1.5 wt%, which are very small amounts. Therefore, when these are to be added in the form of a master alloy, it is difficult to uniformly diffuse them into the Cu molten metal in a short time simply by throwing them into the Cu molten metal. There was a problem that it could be melted.

On the other hand, in order to avoid such a problem, an effective component (Zr, Cr, Ti, etc.) of the master alloy is diluted.
For example, a method using a Cu-3% Zr master alloy has been developed, but it is still impossible to melt a copper alloy having a uniform composition in a short time because the amount of the active metal to be added is very small. Was enough. Therefore, it was difficult to control the content. Furthermore, when attempting to produce a high-performance copper alloy by adding trace amounts of the third and fourth alloy components, uniform melting becomes more difficult, and establishment of an advantageous solution has been required. .

Another problem of the prior art is that during the entire working period of melting copper, charging active metal, and casting (continuous casting), these are performed in a reliable non-oxidizing atmosphere. Another problem is that a healthy copper alloy ingot that has not been oxidized cannot be obtained.

Accordingly, an object of the present invention is to provide a copper alloy having a uniform composition with a small amount of segregation as described above, which is a problem in the prior art when producing a diluted copper alloy containing a trace amount of an active metal element. To propose a copper alloy melting method that not only cannot be manufactured, but also can control the content, and can overcome the problem that it is difficult to continuously cast a sound ingot in an atmosphere that is difficult to oxidize. It is in.

[0008]

Means for Solving the Problems As a result of diligent research to achieve the above object, the inventors have found that a homogeneous dissolution of a trace amount of added components allows a copper alloy having a uniform component composition with little segregation, especially dilute copper. In order to produce alloys with good yield,
The present inventors have found that it is necessary to improve the method of adding and dissolving the active metal, which is a trace addition component, and have reached the present invention as described below. That is, according to the present invention, when adding an active metal or the like to molten copper under a controlled atmosphere in a melting furnace to melt a copper alloy, first, the molten copper is melted in a melting furnace under a vacuum atmosphere to melt copper. After dropping, the inside of the melting furnace was adjusted to an Ar gas atmosphere and maintained for 30 to 120 minutes.After that, the active metal or its mother alloy sealed in the copper tube was charged into the molten copper in the furnace to adjust the components. This is a method for melting copper alloys.
In the above melting method, the superheat of the molten copper after dropping is 150
It is preferable to dissolve while maintaining the temperature within the range of ~ 250 ° C. In addition, in the above melting method, when adding the active metal or its mother alloy, first add a component having a deoxidizing effect, then after 20 to 30 minutes, add the active metal or its mother alloy, After 5 to 10 minutes have elapsed, it is preferable to add and dissolve other necessary additives. In addition, each of the above dissolving methods has an active metal content of 0.2 wt.
%, And 0.5 in the total amount including other additives
It is preferably applied to the production of dilute copper alloys containing less than wt% of additional components.

[0009]

In the present invention, the active metal is Zr, Cr, Ti, A
l, Si, Mg, Be, Ca, Hf, and other elements, which have high reactivity due to high activation energy.
In addition to being easily oxidized when added to the molten Cu,
When these are added in small amounts, it is a metal that is difficult to diffuse quickly into the molten Cu to form a uniform molten alloy. Therefore, when smelting low content dilute copper alloy,
When adding the active metal, first, it is necessary to adjust the atmosphere from the addition to the casting and consider the processing time. Second, it is necessary to uniformly diffuse the molten metal into the molten Cu to obtain a homogeneous alloy. It has been found that it is necessary to study the order of addition and the temperature (superheat) of the molten copper in order to melt the molten metal at a high yield.

For this reason, in the present invention, it has been concluded that the following means for solving the first problem is effective. It is effective that the atmosphere at the time of heating and melting is a vacuum atmosphere, and the atmosphere is maintained at an Ar gas atmosphere during the subsequent holding of the molten metal at the time of copper melting. It is effective to keep the Ar gas atmosphere from the tapping to the completion of continuous casting. As described above, the reason why the operating atmosphere is adjusted to the vacuum atmosphere when the temperature is raised and then to the Ar gas atmosphere is as follows.
In the former case, it is to remove gas components in the molten copper,
In the latter case, when the active element is added, oxygen on the bath surface is eliminated to prevent oxidation of copper.

After the pure copper is melted down, the inside of the melting furnace is maintained in an Ar gas atmosphere, and the holding time is 30 to 120 minutes. The reason why the molten copper is kept in the Ar gas atmosphere for 30 to 120 minutes is to increase the yield of Zr to 80% or more.

Next, in connection with the second problem, the inventors have devised a method of introducing an additive such as an active metal master alloy. The idea is to fill the required amount of active metal to be added, preferably in the form of a mother alloy, into a copper tube, and then add it to the copper melt in the melting furnace with the copper tube. How to In this way, when the active metal and its mother alloy are poured into the molten copper through the copper tube,
Even if an active metal is added, it can be introduced into the melt without oxidizing it, so that the active metal dissolves only in a part of the copper melt and causes segregation as in the past. This is effective in producing a uniform molten alloy. This is more effective when the amount of the active metal to be added is relatively smaller than the amount of the molten copper. In addition, rod-shaped plugs are fitted to the upper and lower opening ends of the above-mentioned copper tube, and the active metal to be filled and sealed therein is scattered by a predetermined timing (when the copper tube is melted), and added. The effect (uniform dispersion) should not be reduced. This plug has a lower (lower) axial length of the plug at the lower open end that is two to three times longer than the plug that fits into the upper open end at the time of insertion. It is desirable to use something.

In the present invention, the form of the active metal to be added may be a simple form of the active metal, but is preferably used in the form of a master alloy. For example, it can be said that about Cu-30% Zr is the most effective composition. With such a master alloy,
The disadvantage of having to prepare an extremely dilute mother alloy (Cu-3% Zr) as in the prior art is also eliminated, and this composition is not preferable if the amount of active metal is too large or too small. In general, it can be said that the use of a Cu- (20-40%) Zr master alloy is preferable.

The next important factor in the present invention is the order of adding the additives. That is, in the present invention, a. First, the deoxidizing component elements, for example, P, Si,
Add Mn, Al, Mg, Zn etc. for a certain time, preferably 20 ~
Hold for 40 minutes. b. Next, an active metal element such as Zr, Ti, Cr or the like, preferably in the form of a master alloy, is added and maintained for a certain time, preferably 3 to 10 minutes. c. Finally, other elements, for example, Fe, Ni, Sn and the like are added as necessary, and the mixture is kept for a certain time, preferably for 10 to 20 minutes. This order of addition is particularly effective when the second and third additional elements are included, and a substance other than the active metal is introduced by wrapping a predetermined amount in a copper foil or the like.

Another important factor when the active metal is charged in the present invention is that the temperature (superheat) of the molten copper kept in the Ar gas atmosphere is higher by 150 to 250 ° C. than its melting point. Are preferred. The reason why the superheat degree of the molten copper is increased in this way is to make the yield of Zr 90% or more.

Regarding the dissolution method of the present invention described above,
Table 1 shows an example of the steps and operating conditions of an example of dissolving a copper alloy obtained by adding Zr, Fe, and P to N copper.

[Table 1]

[0017]

[Example] In this example, a high-frequency vacuum melting furnace (15 KW, Cu
This is an example in which about 1 kg of 5N-Cu was dissolved by using 2 kg). Then, after the Cu has completely melted off, 1000 ppm of Zr in the form of a Cu-Zr mother alloy is put into a copper tube (10 mmφ, wall thickness) in the molten Cu (maintained at about 1300 ° C) in the furnace. : 1 mmt). The added Cu-Zr mother alloy was sealed in a copper tube, and pure Zr was added by wrapping in a copper foil.

(1) Example relating to dissolving conditions FIG. 1 shows that the active metal content (Zr: 50%, 30%, 100%) was changed, and the respective atmospheres (V: It is a result of examining the yield of Zr according to each melting condition when vacuum (A: Ar gas) is changed. As can be seen from the results shown in FIG. 1, when the various melting conditions were changed, the case where the atmosphere at the time of raising the temperature was set to vacuum, and the subsequent holding and addition of the molten metal were all set to the Ar gas atmosphere was the best. And the use of a Cu-30% Zr master alloy showed the best results. That is, the yield in this case is about
It was as good as 80%, but when using Cu-50% Zr master alloy and pure Zr, it was 68-87% and 75-86%, respectively. On the other hand, as for the melting atmosphere, as shown in FIG.
Vacuum atmosphere (about 10 ^-2 Tor) until the base copper is dissolved
r), and the subsequent holding of the molten metal and after the
r The gas atmosphere (-30 cmHg) showed a yield of 86% or more, whereas the vacuum only or vacuum-Ar gas-vacuum only kept 68-84% and 75-80%, respectively. In this melting experiment, the temperature of the molten metal was 1300 ° C., and the holding time of the molten metal was preferably 45 min (yield 99
%). On the other hand, when the molten metal temperature is low (1200 ° C or less)
When the holding time of the molten metal was short (30 min or less), the yield was less than 97%.

(2) Example in which the second and third elements are contained in addition to Zr The amount of each additive is 300 ppm Zr (active metal) (Cu-30% Zr) 2000 ppm Fe (others) (Cu-50% Fe) P (with deoxidizing effect) 555 ppm (Cu-15% P). The order of addition and the holding time of each additive in this experiment are shown in Table 2 together with Comparative Examples. The other dissolution conditions were set under the same conditions as in the above-mentioned good condition (1). That is, a vacuum was set at the time of raising the temperature, an Ar gas atmosphere was set thereafter, and a Cu-30% · Zr mother alloy was added. In this experiment, in the case of the method of the present invention, the additive was added in the order of P → Zr → Fe, and the retention time after the addition was 30 min for P and 5 min for Zr. As a result, as shown in Table 2, the yield of Zr was 95% or more in all cases. That is, in the case of such a multi-component system, it was found that the order of the element having a deoxidizing effect → the active metal element → the other order was good. On the other hand, as comparative examples, Zr was added in other orders, but the yield of Zr was all 90% or less. In addition, when the variation of Zr was investigated for a sample having a good yield, R (maximum value-minimum value) was all 20 ppm or less,
It was found that the uniformity was sufficiently ensured.

[0020]

[Table 2]

(3) The following alloys (36 types) were produced based on the method of the present invention. Zr: 300, 500, 700 ppm Fe: 1000, 2000, 3000 ppm P: 85-1130 ppm The results are shown in Tables 3 and 4. Zr yield is mostly 90
% Or more. Therefore, the method of the present invention can be said to be an excellent method for melting a copper alloy containing an active metal.

[0022]

[Table 3]

[0023]

[Table 4]

[0024]

As described above, according to the present invention, a homogeneous and dilute copper alloy containing an active metal can be produced, and the addition yield of the active metal is high. It can be added at a high yield and a copper alloy having a uniform composition can be obtained. In particular, according to the present invention, it is possible to provide an effective method for inexpensively producing a multi-component copper alloy with less segregation.

[Brief description of the drawings]

FIG. 1 is a comparative graph showing the effect of a difference in Zr content in a master alloy on yield.

FIG. 2 is a comparative graph showing the effect of differences in operating atmosphere on yield.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-61055 (JP, A) JP-A-61-187831 (JP, A) JP-A-57-190763 (JP, A) JP-A-7-87 48639 (JP, A) JP-A-52-136826 (JP, A) JP-A-54-15416 (JP, A) JP-A-54-121226 (JP, A) JP-B-49-17934 (JP, B1) (58) Field surveyed (Int. Cl. ⁷ , DB name) C22C 1/02 C22B 1/00-61/00

Claims (4)

(57) [Claims] 1. To melt a copper alloy by adding an active metal or the like to molten copper in a controlled atmosphere in a melting furnace, pure copper is first melted in a melting furnace in a vacuum atmosphere. After dropping, the inside of the melting furnace was adjusted to an Ar gas atmosphere and maintained for 30 to 120 minutes.After that, the active metal or its mother alloy sealed in the copper tube was charged into the molten copper in the furnace to adjust the components. Characteristic copper alloy melting method. 2. The method for melting a copper alloy according to claim 1, wherein the superheat degree of the molten copper after the melting is maintained at a temperature within a range of 150 to 250 ° C. 3. The melting method according to claim 1, wherein, when adding the active metal or its mother alloy, first,
A component having a deoxidizing effect is added, and after 20 to 30 minutes, the active metal or its mother alloy is added.
A method for melting a copper alloy, which comprises adding another necessary additive after a lapse of about 10 minutes. 4. The method according to claim 1, wherein the content of the active metal is less than 0.2 wt%, and the total amount of the additional components including other additives is less than 0.5 wt%. A method for melting a copper alloy, which is applied to the melting of a dilute copper alloy containing: