JPS5824495B2 - Manufacturing method of heat-resistant conductive aluminum alloy - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method for producing a heat-resistant conductive aluminum alloy containing zirconium, which appropriately improves the heat resistance of the conductive aluminum alloy and also stably and improves its conductivity. The present invention is intended to provide a preferable manufacturing method.

Aluminum has good electrical conductivity and has been widely used as a conductive material for power transmission lines, etc., but the current aluminum produced by electrolytic smelting using alumina extracted from bauxite is a trace amount of Ti,
It contains V, and these Ti' and V extremely lower the electrical conductivity of aluminum, so it is necessary to remove these Ti' and V when using it as a conductive material.

However, the removal of Ti and V is generally performed by adding an aluminum boron mother alloy or an alkali borofluoride to the molten aluminum obtained by the above-mentioned electrolytic smelting method or the molten aluminum obtained by remelting the base metal. This is done by adding and stirring to react and remove Ti, V and B in the molten aluminum.

However, when producing heat-resistant conductive alloys, Ti removal,
Zr is added to V-treated molten aluminum to impart heat resistance, and the molten aluminum is used to make power transmission lines and the like.

However, when Zr is added to molten aluminum in this way, although the heat resistance of the aluminum improves, it tends to lower the electrical conductivity, so it is not preferable to add more than necessary, and when the amount added varies. It is desirable to control the content within a certain range as much as possible because it causes variations in the conductivity of the conductive aluminum alloy and makes it impossible to obtain a product with stable performance.

By the way, conventionally, this type of heat-resistant conductive aluminum alloy has been made by adding an aluminum zirconium master alloy to molten aluminum that has been subjected to Ti and V treatment using the general method described above to contain Zr in the aluminum. However, by using such a method, it is not necessarily possible to obtain a conductive aluminum alloy with the desired conductive performance, and there is also a large variation in performance between manufacturing lofts and within the same lot, which is not desirable. .

Moreover, the aluminum zirconium master alloy is not easily dissolved in molten aluminum and requires a considerable amount of time, about 6 to 8 hours, to produce it, which reduces work efficiency.

The present invention was devised after repeated studies in view of the above-mentioned circumstances, and in producing the above-mentioned Zr-containing heat-resistant conductive aluminum alloy, the molten aluminum contains boron-free Ti, V After adding the auxiliary agent and causing the Ti and (1) in the molten aluminum to react with the B in the auxiliary agent as fully as possible and removing harmful Ti and V, the molten metal is acidified or the molten metal is solidified once. This method is characterized in that an alkali zirconium fluoride is added to the molten metal obtained by re-melting the molten metal, so that Zr is contained in the aluminum.

That is, to explain the present invention in further detail,
Conventionally, when adding Zr to an aluminum alloy, an aluminum zirconium master alloy containing 3 to 5% Zr in aluminum has been used, but this is based on new findings by the present inventors.

Therefore, Zr in this mother alloy exists as aluminum zirconium intermetallic compounds in various forms, and depending on the form, it is extremely difficult to dissolve in molten aluminum, and the content of such poorly soluble intermetallic compounds As mentioned above, the amount of Zr is not constant, and as a result, a considerable amount of time is required for its melting, and furthermore, the amount of Zr in the obtained product varies.

As a result of many practical studies, the present inventors confirmed that zirconium fluoride alkali is a preferable Zr additive.

The alkali zirconium fluoride used in the lid has excellent reactivity with molten aluminum, and when added to the molten aluminum, almost all of the Zr contained therein can be dissolved very quickly, thus stabilizing the desired amount of Zr. In this way, compared to the case of adding the above-mentioned master alloy, contamination of iron and silicon can be avoided, so that the conductive performance of aluminum is improved. It is possible to stably obtain the target conductive aluminum alloy having the desired conductivity and heat resistance with less deterioration and with favorable working efficiency.

In particular, in cases where a conductive aluminum alloy that requires a high degree of heat resistance and conductivity is to be obtained more stably, it is recognized that simply carrying out the above method tends to be insufficient. As a result of further studies on this point, they found that the reaction between Ti and V in the molten aluminum and B in the boron-containing auxiliary is unstable when adding the boron-based auxiliary for removing Ti and V as described above. Therefore, even slight differences in molten metal temperature, stirring conditions, etc. will cause the reaction to be inconsistent, and the reaction will be even more variable, especially when using an auxiliary agent that contains a volatile substance such as an alkali borofluoride. It is known that even if a certain amount of boron-containing auxiliary agent is used, it is difficult to obtain effective removal of Ti and V.

For this purpose, it is common to add a slightly excessive amount of boron-containing auxiliary agent to ensure sufficient removal of Ti and V. Moreover, if an excessive amount of boron-containing auxiliary agent is added in this way, there will be no reaction in the molten aluminum. Active boron compounds such as boron or boron fluoride remain, and this reacts with the zirconium in the aluminum zirconium mother alloy that is added next, consuming a part of the Zr in the mother alloy and significantly reducing the heat resistance of aluminum. Sometimes.

However, when unreacted boron or active boron compounds are present in the molten aluminum, a small amount of alkali zirconium fluoride is added to the molten aluminum, and the Zr in the alkali zirconium fluoride is combined with the unreacted boron or active boron. When the zirconium boride is reacted with a compound to form zirconium boride, which has little effect on heat resistance and conductivity, and then the zirconium fluoride alkali is added to the molten aluminum again, an effective heat-resistant and conductive material containing the desired amount of Zr can be obtained. It was confirmed that aluminum alloys can be produced stably.

The present invention has been completed based on a series of new findings as described above, and when the method of the present invention is used, the increase in iron and silicon is smaller than in the conventional method using an aluminum zirconium master alloy. , both of its conductive performance and heat resistance performance are improved, and a stable conductive aluminum alloy can be produced quickly and efficiently, especially when using a method of adding zirconium fluoride alkali in two or more parts. can produce the alloys more stably even when their performance is required to a higher degree.

Specific embodiments of the present invention will be described below.

Example I In producing heat-resistant conductive aluminum containing 0.10% Zr, aluminum containing iron and silicon (Si:O, O4%, Fe2 0.12%, Cu
: 0.002%, Ti: 0.005%, V: 0.003
%, Mn: 0.002%) was melted in a melting furnace and kept at 800°C, and 4.5 kg of industrial soda borofluoride as an alkali borofluoride was added to this molten aluminum.
was added and stirred in a well-lined phosphor sulfurizer, treated with Ti and V, and allowed to pass for 1 hour. Then, as zirconium fluoride alkali, 35 kg of industrial potassium zirconium fluoride was added to the molten metal at 750°C in the same manner as above. After adding and stirring with a jig and removing floating slag on the surface of the molten metal, the composition was immediately analyzed and the result was Zr: 0.11%, Fe20.
．． 12%, and Si: 0.04%.

However, when this product was analyzed for composition after 3 hours, Z
It was found that r was 0.09%, and a part of Zr became a boron compound and precipitated.

However, according to the method described above, the standard deviation of the amount of Zr was found to be σ-0.006% as a result of repeatedly producing an aluminum alloy six times.

On the other hand, for comparison, a heat-resistant conductive aluminum alloy containing 0.10% Zr using an aluminum zirconium mother alloy was added to the molten aluminum having the same composition as described above, and was subjected to industrial borofluorination as an alkali borofluoride. Soda was added and stirred at the same time, Ti and V were removed, and 1 hour later, aluminum alloy containing 3.5% Zr was obtained.

Ruconium master alloy (zr: 3.s%, Fe: 0.13%
, Si: 0.05%) 32 ok19 was added to a molten metal at 750°C and stirred thoroughly in the same manner as described above.

That is, the result of analyzing the composition of this molten metal is that Zr is 0.08%.
, Fe was 0.13%, and Si was 0.04%.

The composition of the molten metal was again analyzed after 3 hours, and it was found that the Zr content was 0.10%, an increase of 0.02%.

Furthermore, the standard deviation of the Zr content in the results of repeated production six times using this comparative method was σ=0.004%.

In other words, the above results confirm that the melting and diffusion time of the aluminum zirconium master alloy is much longer than that of zirconium potassium fluoride, which means that it takes a lot of time to melt the heat-resistant conductive aluminum alloy, which reduces work efficiency. It is clear that depending on the amount of undissolved zirconium, it has a large influence on the loft or the next loft.

Example 2 In producing a heat-resistant conductive aluminum alloy containing 0.10% Zr, 10,550 kg of the same aluminum as in Example 1 was melted in a melting furnace, maintained at 800°C, and the molten aluminum was heated to 800°C. 4.5 kg of industrial sodium borofluoride was added as an alkali and stirred using the same phosphorizer as in Example 1. After 1 hour of Ti and V treatment, industrial zirconium fluoride was added as an alkali. 1.5 kg of potassium was added and stirred in the same manner as above, and the molten metal was analyzed after 1 hour, and the Zr content was 0.02.
%, which indicates that about 60% of the Zr added to the molten metal as the potassium zirconium fluoride precipitated as boride.

Next, the difference from the Zr target value in the molten metal is 0.10-0.
One hour after the first addition of zirconium potassium fluoride, 32 kg of industrial potassium zirconium fluoride (0.002 = 0.098%) was added and stirred in the same manner as described above. Analysis of the molten metal composition revealed that Zr was 0.10%, Fe was 0.12%, and S
i was 0.04%.

When analyzed again two hours later, the Zr content was 0.10%, which was the same value.

Furthermore, the standard deviation value of the Zr amount for the results of 120 repeated tests using the same method as described above is σ=
0.002%, and from these results, it is better to introduce the Zr additive in two or more divided doses than to introduce it all at once, which results in less variation in the electrical conductivity and heat resistance performance of zirconium-containing additives. It was confirmed that it is possible to produce a stable aluminum alloy for conductive use.

According to the present invention as explained above, it is possible to efficiently obtain a heat-resistant conductive aluminum alloy through a melting process within a relatively short time, and to ensure both its conductivity and heat resistance stably and appropriately. This is an invention that has great industrial effects.

Claims (1)

[Scope of Claims] 1. A molten aluminum containing boron-free titanium, a vanadium auxiliary agent added to the molten aluminum, and titanium and vanadium in the molten aluminum reacting with boron in the auxiliary agent to remove the titanium and vanadium; or A method for producing a heat-resistant conductive aluminum alloy, which comprises adding and mixing zirconium fluoride alkali to the molten metal which has been solidified and then remelted to incorporate zirconium into the aluminum. 2. Claim 1, wherein the alkali zirconium fluoride is added and mixed in multiple steps, and at the time of final addition, the alkali zirconium fluoride is added in an amount commensurate with the difference between the amount of analyzed zirconium immediately before and the target amount of zirconium. A method for producing a heat-resistant conductive aluminum alloy as described in .