TWI877865B - Aluminum alloy conductive material and method of manufacturing the same - Google Patents

Abstract

The present invention is related to an aluminum alloy conductive material and a method of manufacturing the same. In the method, a homogeneous step is performed at a specific temperature for a specific time, so that the conductivity of the obtained aluminum alloy conductive material increases. Thus, the method allows making the aluminum alloy conductive material with an excellent conductivity out of a material of melt aluminum alloy with a lower aluminum amount, such as recycled aluminum, and can therefore reach the goal of cost down and/or sustainable development.

Description

Aluminum alloy conductive material and manufacturing method thereof

The present invention relates to an aluminum alloy conductive material and a manufacturing method thereof, and in particular to an aluminum alloy conductive material with a relatively low aluminum content and a manufacturing method thereof.

Aluminum is one of the most abundant metals on earth. It is widely used in industry because of its light weight, strength, corrosion resistance, formability, surface treatment, electrical conductivity, thermal conductivity, processability, welding and regeneration. Aluminum's electrical conductivity is about 60% of copper, but it is light and cheap, so it is often used as a conductor.

The higher the aluminum content in aluminum, the better the conductivity of the aluminum. Under the requirement of high conductivity, the conventional method is to increase the aluminum content of the aluminum so that the aluminum content of the aluminum is close to that of pure aluminum. However, the higher the aluminum content requirement of the aluminum, the higher the cost, and it is not conducive to adding recycled aluminum to the aluminum, which is not in line with the sustainable development trend of increasing the proportion of recycled aluminum in recent years.

Therefore, a method for manufacturing an aluminum alloy conductive material is urgently needed to solve the above problems.

Therefore, one aspect of the present invention is to provide a method for manufacturing an aluminum alloy conductive material, which is to perform a forming step, a homogenizing step and a hot rolling step on a molten aluminum alloy material with a relatively low aluminum content to obtain an aluminum alloy conductive material with high conductivity.

Another aspect of the present invention is to provide an aluminum alloy conductive material, which is manufactured by the above-mentioned manufacturing method and has high conductivity.

According to the above aspects of the present invention, a method for manufacturing an aluminum alloy conductive material is provided. First, a molten aluminum alloy material is provided, wherein the molten aluminum alloy material comprises 0.05 weight percent to 0.20 weight percent of iron, less than or equal to 0.10 weight percent of silicon, one or more impurities with a total amount less than or equal to 0.20 weight percent, and greater than or equal to 99.6 weight percent of aluminum. Then, the molten aluminum alloy material is subjected to a forming step to obtain an aluminum billet. Then, the aluminum billet is subjected to a homogenization step at 400° C. to 500° C. for 10 hours to 15 hours to obtain a homogenized aluminum billet. Next, the homogenized aluminum billet is subjected to a hot rolling step to obtain an aluminum alloy conductive material.

In one embodiment of the present invention, the impurity(ies) include chromium, magnesium and/or titanium.

In one embodiment of the present invention, the forming step is a casting forming step.

In one embodiment of the present invention, the manufacturing method may optionally include pre-treating the homogenized aluminum billet at 500° C. to 540° C. before the hot rolling step.

In one embodiment of the present invention, the hot rolling step is performed at 300°C to 500°C.

In one embodiment of the present invention, the manufacturing method may optionally include a cooling process after the hot rolling step to cool the aluminum alloy conductive material to room temperature.

According to another aspect of the present invention, an aluminum alloy conductive material is provided, which is manufactured by the above manufacturing method. The conductivity of the aluminum alloy conductive material is greater than or equal to 61% of the International Annealed Copper Standard (IACS).

In one embodiment of the present invention, the aluminum alloy conductive material includes nanoparticles of Al ₃ Fe and/or α-AlFeSi.

The aluminum alloy conductive material and the manufacturing method thereof of the present invention are applied, wherein the manufacturing method includes a homogenization step to precipitate impurities, so that the aluminum alloy conductive material with high conductivity can be prepared from the molten aluminum alloy material with a relatively low aluminum content.

The following detailed description and the accompanying drawings are used to describe the embodiments of the present invention in detail. The same figure numbers used in the drawings and the specification refer to the same or similar parts as much as possible.

As mentioned above, the present invention provides an aluminum alloy conductive material and a method for manufacturing the same, wherein the method includes a homogenization step to precipitate impurities, so that a molten aluminum alloy material with a relatively low aluminum content can be used to produce an aluminum alloy conductive material with a high conductivity.

The "lower aluminum content" of the molten aluminum alloy material described in the present invention is relative to pure aluminum. In some embodiments, the lower aluminum content means that the aluminum content of the molten aluminum alloy material is greater than or equal to 99.6 weight percent. In some embodiments, the lower aluminum content means that the aluminum content of the molten aluminum alloy material is greater than or equal to 99.6 weight percent and less than 99.8 weight percent.

The "high conductivity" mentioned in the present invention refers to the good ability of the aluminum alloy conductive material to transmit electric current. In some embodiments, the conductivity of the aluminum alloy conductive material with high conductivity is greater than or equal to 60% of the International Annealed Copper Standard (IACS). In some embodiments, the conductivity of the aluminum alloy conductive material with high conductivity is greater than or equal to 60.5% IACS, or greater than or equal to 61% IACS. It should be noted that 100% IACS refers to the conductivity of a standard annealed copper sample with a purity of 100% and a density of 8.95 g/ ^cm3 at 20°C.

Please refer to FIG. 1, which is a flow chart of a method for manufacturing an aluminum alloy conductive material according to an embodiment of the present invention. First, step 110 is performed to provide a molten aluminum alloy material. The molten aluminum alloy material may include iron, silicon, one or more impurities and aluminum, wherein the iron content may be, for example, 0.05 weight percent to 0.20 weight percent. In some embodiments, the iron content of the molten aluminum alloy material may be, for example, 0.15 weight percent to 0.20 weight percent. If the iron content is too high, the aluminum alloy conductive material obtained is prone to brittleness, affecting subsequent processability. If the iron content is too low, the conductivity of the aluminum alloy conductive material obtained will be too low.

The silicon content of the molten aluminum alloy material may be, for example, less than or equal to 0.10 weight percent, such as greater than 0 weight percent and less than or equal to 0.10 weight percent. In some embodiments, the silicon content of the molten aluminum alloy material may be, for example, 0.05 weight percent to 0.10 weight percent. If the silicon content is too high, the subsequent homogenization step cannot cause the excess silicon to precipitate, so that the conductivity of the obtained aluminum alloy conductive material is too low. However, if a molten aluminum alloy material with too low a silicon content is used, it will lead to a significant increase in costs. One of the features of the present invention is that it allows the molten aluminum alloy material to have a higher silicon content, but still produces an aluminum alloy conductive material with high conductivity.

The total amount of one or more impurities in the molten aluminum alloy material may be, for example, less than or equal to 0.20 weight percent, such as greater than 0 weight percent and less than or equal to 0.20 weight percent. Impurities are other elements in the molten aluminum alloy material that cannot be separated, other than silicon, iron, and aluminum. In some embodiments, the impurities may include, but are not limited to, chromium, magnesium, and/or titanium.

The aluminum content of the molten aluminum alloy material may be, for example, greater than or equal to 99.6 weight percent. In some embodiments, the aluminum content of the molten aluminum alloy material is greater than or equal to 99.6 weight percent to less than 99.8 weight percent. In some embodiments, the aluminum content of the molten aluminum alloy material is greater than or equal to 99.6 weight percent to less than 99.7 weight percent.

Following step 110 is step 120, which is to perform a forming step on the molten aluminum alloy material to obtain an aluminum blank. The method of the forming step is not particularly limited, and the molten aluminum alloy material can be formed by cooling. In some embodiments, the forming step can be, for example, a casting forming step.

Next, the aluminum billet is subjected to a homogenization step to obtain a homogenized aluminum billet, as shown in step 130. During the homogenization step, iron, silicon and/or impurities in the aluminum billet are precipitated from the purified aluminum-based phase to form particles. In some embodiments, these particles are nano-scale particles, and the particle size may be, for example, 1 nm to 50 nm. In some embodiments, these particles may be, for example, trialuminum (Al ₃ Fe) and aluminum ferrosilicon (α-AlFeSi).

The time and temperature of the homogenization step will affect the precipitation degree of iron, silicon and impurities, thereby affecting the conductivity of the aluminum alloy conductive material produced. In other words, if the homogenization step time is too short or the temperature is too low, the precipitation degree of iron, silicon and impurities is low. On the contrary, if the homogenization step time is too long or the temperature is too high, iron, silicon and impurities will dissolve back after precipitation, resulting in poor conductivity of the aluminum alloy conductive material produced.

The temperature of the homogenization step may be, for example, greater than 350°C and less than 550°C, or 380°C to 530°C. In some preferred embodiments, the temperature of the homogenization step may be, for example, 400°C to 500°C, such as 430°C to 480°C. In some embodiments, the time of the homogenization step may be, for example, greater than or equal to 5 hours and less than or equal to 15 hours. In some embodiments, when the temperature of the homogenization step is greater than 350°C and less than 400°C, or greater than 500°C and less than 530°C, the time of the homogenization step is greater than or equal to 10 hours and less than 15 hours. When the temperature of the homogenization step is 400°C to 500°C, the time of the homogenization step may be, for example, 10 hours to 15 hours.

After the homogenization step, step 140 may be performed to perform a hot rolling step on the homogenized aluminum billet to obtain an aluminum alloy conductive material. The hot rolling step may be performed in a known manner, such as at 300° C. to 500° C. There are no particular restrictions on the time and amount of the hot rolling step. In some embodiments, the time of the hot rolling step may be, for example, 0.5 hours to 2 hours. In some embodiments, the amount of hot rolling may be, for example, 30% to 80%.

In some embodiments, before the hot rolling step, the homogenized aluminum billet can be placed in a preheating furnace for pretreatment. In some specific examples, the temperature of the preheating furnace is maintained at 500° C. to 540° C. In some specific examples, the pretreatment time can be, for example, at least 2 hours, such as 2 hours to 4 hours. In some embodiments, after the hot rolling step, a cooling treatment can be selectively performed to cool the aluminum alloy conductive material to room temperature. The method of cooling treatment is not particularly limited, and can be, for example, placing the aluminum alloy conductive material indoors.

Experiments have confirmed that, under an optical microscope, the structure of the homogenized aluminum billet obtained after the homogenization step does contain particles of iron, silicon and/or impurities precipitated, compared with the aluminum billet without the homogenization step.

Secondly, the aluminum alloy conductive material obtained from the aluminum billet after the homogenization step has a higher conductivity than the aluminum billet without the homogenization step. In some embodiments, the conductivity of the aluminum alloy conductive material may be greater than 60% IACS, or greater than 61% IACS, or greater than or equal to 61.5% IACS.

It is worth noting that the conductivity of the aluminum alloy conductive material obtained through the homogenization step can even be greater than the conductivity of the aluminum alloy conductive material obtained by using a molten aluminum alloy material with a higher aluminum content. In other words, in order to obtain an aluminum alloy conductive material with a conductivity that meets the requirements, the conventional manufacturing method has a higher requirement for the aluminum content of the molten aluminum alloy material. However, because the manufacturing method described in the present invention includes a homogenization step, it is possible to use a molten aluminum alloy material with a lower aluminum content and a higher iron, silicon and/or impurity content to obtain an aluminum alloy conductive material with a conductivity that meets or even exceeds the requirements, thereby solving the problem that the conventional manufacturing method of aluminum alloy conductive materials is not conducive to adding recycled aluminum.

Several embodiments are used below to illustrate the application of the present invention, but they are not intended to limit the present invention. Those with ordinary knowledge in the technical field of the present invention can make various changes and modifications without departing from the spirit and scope of the present invention. Embodiment 1

A molten aluminum alloy material was prepared, which contained 0.07 weight percent of silicon, 0.16 weight percent of iron, 0.17 weight percent of impurities in total, and 99.6 weight percent of aluminum.

The molten aluminum alloy material is subjected to a forming step so that the molten aluminum alloy material is cast into an aluminum billet. Then, the aluminum billet is placed in a hot furnace at 380°C for 5 hours to perform a homogenization step to obtain a homogenized aluminum billet. Then, the homogenized aluminum billet is placed in a preheating furnace for pretreatment. The temperature of the preheating furnace is maintained at 500°C to 540°C, and the pretreatment is performed for at least 2 hours. After pretreatment, the homogenized aluminum billet is subjected to a hot rolling step at 400°C to 500°C to form an aluminum coil. Example 2 to Example 12

The manufacturing method of the aluminum coil of Examples 2 to 12 is the same as that of Example 1, and the difference lies in the temperature and time of the homogenization step. The temperature and time of the homogenization step of Examples 2 to 12 are recorded in Table 1. Comparative Example 1

The manufacturing method of the aluminum coil of Comparative Example 1 is the same as that of Example 1, except that the homogenization step is not performed. Comparative Example 2 to Comparative Example 3

The manufacturing method of the aluminum coils of Comparative Examples 2 to 3 is the same as that of Comparative Example 1, except that the molten aluminum alloy material used in Comparative Example 2 contains 0.06 weight percent silicon, 0.08 weight percent iron, a total of 0.06 weight percent impurities, and 99.8 weight percent aluminum, and the molten aluminum alloy material used in Comparative Example 3 contains 0.07 weight percent silicon, 0.17 weight percent iron, a total of 0.06 weight percent impurities, and 99.7 weight percent aluminum. Evaluation method Observation of material structure

Before and after the homogenization step, an electron microscope was used to observe whether there were particles precipitated in the material structure of the aluminum coils of Examples 1 to 12. Conductivity

According to the copper wire table specifications issued by the National Bureau of Standards (USA, the predecessor of the National Institute of Standards and Technology), the conductivity of the aluminum coil is tested using a conductivity meter, and the unit is the percentage of IACS. The conductivity results are recorded in Table 1. Table 1 Molten aluminum alloy material (weight percentage) Homogenization step Conductivity(% IACS) Silicon Iron Impurities Aluminum Temperature(℃) Time(hours) Embodiment 1 0.07 0.16 0.17 99.6 380 5 60 Embodiment 2 430 5 60.2 Embodiment 3 480 5 60.4 Embodiment 4 530 5 60.1 Embodiment 5 380 10 60.7 Embodiment 6 430 10 62.2 Embodiment 7 480 10 62 Embodiment 8 530 10 60.8 Embodiment 9 380 15 60.3 Embodiment 10 430 15 61.7 Embodiment 11 480 15 61.5 Embodiment 12 530 15 60.4 Comparison Example 1 N/A N/A 59.6 Comparison Example 2 0.06 0.08 0.06 99.8 N/A N/A 61.2 Comparison Example 3 0.07 0.17 0.06 99.7 N/A N/A 60.4

As shown in Table 1, it can be seen from Comparative Examples 1 to 3 that the aluminum content of the molten aluminum alloy material is positively correlated with the conductivity of the aluminum coil produced, and if the aluminum content in the molten aluminum alloy material is only 99.6 weight percent, the aluminum coil produced does not have a high conductivity (i.e., 60% IACS).

However, as shown in Comparative Example 1 and Examples 1 to 12 in Table 1, the homogenization step can indeed increase the conductivity of the aluminum coil produced. Secondly, as shown in Comparative Example 2, Comparative Example 3 and Examples 1 to 12, the homogenization step can make the conductivity of the aluminum coil produced from the molten aluminum alloy material with a lower aluminum content (i.e., 99.6 weight percent) greater than the conductivity of the aluminum coil produced from the molten aluminum alloy material with a higher aluminum content (i.e., 99.7 weight percent to 99.8 weight percent).

In other words, when the homogenization step is performed at 380° C. or 530° C. for 10 hours (Examples 5 and 8), the conductivity of the aluminum coil obtained is 60.7% IACS to 60.8% IACS, which is greater than the conductivity of the aluminum coil obtained using a molten aluminum alloy material having an aluminum content of 99.7 weight percent (60.4% IACS, Comparative Example 2).

Secondly, when the homogenization step is performed at 430° C. to 480° C. for 10 hours to 15 hours, the conductivity of the aluminum coil obtained is 61.5% IACS to 62.2% IACS (Examples 6, 7, 10, and 11), which is greater than the conductivity of the aluminum coil obtained using a molten aluminum alloy material having an aluminum content of 99.8 weight percent (61.2% IACS, Comparative Example 1).

However, if the homogenization step is performed at 380°C to 530°C for 5 hours (Examples 1 to 4), the conductivity of the obtained aluminum coil is only 60% IACS to 60.4% IACS, indicating that the short homogenization time may result in insufficient precipitation of iron, silicon and/or impurities, and thus the obtained aluminum coil has insufficient purified aluminized base phase. If the homogenization step is performed at 380°C or 530°C for 15 hours (Examples 9 and 12), the conductivity of the obtained aluminum coil is 60.3% IACS to 60.4% IACS, which is slightly lower than the case where the homogenization step is performed at the same temperature for 10 hours (Examples 5 and 8), indicating that the homogenization step is performed for too long, which may cause the precipitated particles of iron, silicon and/or impurities to dissolve back into the purified aluminum base phase.

As described above, in the homogenization step, the precipitation amount of iron, silicon and/or impurities from the purified aluminum base phase can be increased, thereby increasing the conductivity of the aluminum coil produced subsequently. Please refer to Figures 2A and 2B, which are optical microscope photos of the structure of an aluminum billet (without homogenization step, Figure 2A) and a homogenized aluminum billet (after homogenization step, Figure 2B) according to an embodiment of the present invention. As shown in Figures 2A and 2B, the aluminum billet has few nanoparticles, but after the homogenization step, the nanoparticles of the homogenized aluminum billet produced increase. After analysis, these nanoparticles are trialuminum (Al ₃ Fe) and α-AlFeSi. It can be seen that the homogenization step can indeed cause iron, silicon and/or impurities to precipitate from the purified aluminum base phase, thereby achieving the same effect as purifying aluminum alloys and increasing the conductivity of the resulting aluminum coil.

As can be seen from the above embodiments, the aluminum alloy conductive material and the manufacturing method thereof of the present invention have the advantage that the homogenization step is carried out at a specific temperature for a specific time, and the molten aluminum alloy material with a relatively low aluminum content can be used to produce an aluminum alloy conductive material with a high conductivity. Therefore, it can be applied to the manufacture of aluminum alloy conductive materials, especially the manufacture of aluminum alloy conductive materials with a high conductivity, or the manufacture of aluminum alloy conductive materials with recycled aluminum.

Although the present invention has been disclosed as above with several specific embodiments, various modifications, changes and substitutions may be made to the above disclosed contents, and it should be understood that, without departing from the spirit and scope of the present invention, certain features of the embodiments of the present invention will be adopted in certain situations but other features will not be used accordingly. Therefore, the spirit and scope of the claims of the present invention should not be limited to the above exemplary embodiments.

110,120,130,140: Steps

In order to make the above and other purposes, features, advantages and embodiments of the present invention more clearly understandable, the attached figures are described in detail as follows: FIG. 1 is a flow chart of a method for manufacturing an aluminum alloy conductive material according to an embodiment of the present invention. FIG. 2A and FIG. 2B are optical microscope photographs of the structure of an aluminum billet and the aluminum billet after homogenization according to an embodiment of the present invention.

110,120,130,140: Steps

Claims (8)

A method for manufacturing an aluminum alloy conductive material comprises: providing a molten aluminum alloy material, wherein the molten aluminum alloy material comprises: 0.05 weight percent to 0.16 weight percent of iron; less than or equal to 0.10 weight percent of silicon; one or more impurities with a total amount less than or equal to 0.20 weight percent; and 99.6 weight percent to less than 99.7 weight percent of aluminum; The material is subjected to a forming step to obtain an aluminum billet; the aluminum billet is subjected to a homogenization step at 400°C to 500°C for 10 hours to 15 hours to obtain a homogenized aluminum billet; and the homogenized aluminum billet is subjected to a hot rolling step to obtain the aluminum alloy conductive material, wherein the aluminum alloy conductive material has a conductivity greater than or equal to 61% of the International Annealed Copper Standard (IACS). A method for manufacturing an aluminum alloy conductive material as described in claim 1, wherein the impurities or impurities contain chromium, magnesium and/or titanium. The method for manufacturing an aluminum alloy conductive material as described in claim 1, wherein the forming step is a casting forming step. The manufacturing method of the aluminum alloy conductive material as described in claim 1 further includes pre-treating the homogenized aluminum billet at 500°C to 540°C before the hot rolling step. The method for manufacturing an aluminum alloy conductive material as described in claim 1, wherein the hot rolling step is performed at 300°C to 500°C. The method for manufacturing the aluminum alloy conductive material as described in claim 1 further includes performing a cooling treatment after the hot rolling step to cool the aluminum alloy conductive material to room temperature. An aluminum alloy conductive material is produced by the manufacturing method described in any one of claim 1 to claim 6. The aluminum alloy conductive material as described in claim 7, wherein the aluminum alloy conductive material comprises nanoparticles of Al ₃ Fe and/or α-AlFeSi.