Both aluminum and aluminum alloy conductors have the ability to conduct electricity, and the resistance of the two is different. The aluminum alloy conductor is added relevant trace elements in the aluminum conductor, so that its resistivity is lower than the pure aluminum conductor, which solves the disadvantages of poor mechanical properties, easy breakage and easy creep of pure aluminum cables, also avoids the investment problems caused by the high copper price.
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Aluminum is a silver-white light metal with a density of 2.7 g/mm³, which is about 30.3% of copper. Aluminum has good electrical conductivity. Compared with copper, when the cross section is the same, the conductivity of aluminum per unit length is 64% of copper. If calculated according to the same mass of aluminum and copper, the conductivity of aluminum is equivalent to 200% of copper, which is greatly exceeded copper. Aluminum has good thermal conductivity, and its thermal conductivity is 56% of copper. Aluminum is acid-resistant, but not alkali-resistant, nor salt-spray corrosion-resistant. It has good plasticity and is easy to be processed by pressure. The disadvantage is that its strength is lower than that of copper and its welding performance is poor. But aluminum resources are abundant and its price is low.
The difference between aluminum alloy conductors and pure aluminum conductors is that aluminum alloy conductors add copper, iron, magnesium and other elements on the basis of pure aluminum, and these elements play a very critical role in aluminum alloys:
Copper: Increase the resistance stability of the alloy at high temperature. Copper is an important alloying element and has a certain solid solution strengthening effect. In addition, the CuAl2 phase precipitated by aging has an obvious aging strengthening effect. The copper content in aluminum alloys is usually 2.5% ~5 . 0%.
Iron: Increased creep resistance and compaction by 280%, avoiding the relaxation problem caused by creep.
Magnesium: Under the same interfacial pressure, it can increase the contact point and have higher tensile strength. The strengthening of magnesium to aluminum is obvious, and the tensile strength will increase by about 34 MPa for every 1% increase in magnesium. If less than 1% manganese is added, it can play a supplementary strengthening role. Therefore, the content of magnesium in most industrial deformed aluminum alloys is less than 6%.
Aluminum alloy conductors and copper conductors have different electrical conductivity due to the difference in resistivity. The conductivity of aluminum alloy is 61.8% of copper. When we increase the cross-sectional area of &#;&#;the aluminum alloy conductor by two gears or increase it to 150% of the cross-sectional area of &#;&#;the copper conductor, its electrical performance is consistent.
The tensile strength of aluminum alloy conductor is only half of copper conductor (113.8:220 MPa). Since the density of the aluminum alloy is only 30.4% of the copper conductor, even if the cross-sectional area of &#;&#;the aluminum alloy conductor is increased to 150% of the copper conductor, the weight of the aluminum alloy conductor is only 45% of the copper conductor, which makes the tensile strength of the aluminum alloy conductor also has certain advantages over copper conductors.
Due to the good electrical conductivity and excellent mechanical properties of aluminum alloy conductors, the disadvantages of unreliable connection, poor mechanical strength, and easy creep of aluminum conductors are improved. The mechanical properties of aluminum alloy conductors are similar to copper conductors, and the electrical properties have the same conductivity as copper conductors by increasing the cross-sectional area. It will be widely used in power distribution systems.
If you are a designer or engineer, aluminum is undoubtedly a high-quality basic material worth considering when designing products related to conductivity. Especially in applications that require precision parts and efficient current conduction, the high conductivity of aluminum makes it an ideal choice. By fully utilizing the electrical characteristics of aluminum, you can design more efficient and reliable products to meet the needs of customers.
Aluminum is a metal element in the periodic table with the atomic number 13. It is one of the most abundant metals found on Earth, constituting about 8% of the Earth&#;s crust.
The atomic number 13 signifies the presence of 13 electrons in an aluminum atom, arranged in electron orbitals. In metals, electrical conductivity is largely determined by the availability of free electrons that can move through the material. In aluminum, the three electrons in the outer shell are relatively free to move, facilitating the conduction of electricity.
However, aluminum does not exist in its pure form naturally and must be produced on an industrial scale from its ore&#;bauxite. It undergoes refining to extract aluminum oxide, which is then subjected to electrolysis to obtain pure aluminum metal.
Can Aluminum Conduct Electricity?Indeed, aluminum is among the top materials for electrical conductivity, second only to pure copper. Pure aluminum boasts a remarkable conductivity of 37.7 MS/m, making it highly effective for various electrical uses.
To understand aluminum&#;s efficiency as a conductor, it&#;s often compared to copper, which is the leading conductor after silver. However, due to silver&#;s high cost, it is not feasible for extensive industrial applications. This is where aluminum becomes advantageous as a cost-efficient alternative.
The International Annealed Copper Standard (IACS) provides a basis for comparing electrical conductivity across materials. Aluminum stands at 61% IACS, indicating it has 61% of the conductivity of copper. While this is less than copper, it is still highly effective, particularly in applications where weight and cost are crucial factors.
In practice, aluminum&#;s conductivity is so reliable that most power transmission lines utilize aluminum. This means the electricity reaching your home likely travels through aluminum conductors. Moreover, aluminum&#;s resistance to corrosion enhances its durability, making it a long-lasting choice for electrical infrastructure.
How Does Aluminum Conduct Electricity?The exceptional conductivity of aluminum arises from its atomic makeup and the way its atoms bond. Aluminum atoms consist of a nucleus made up of protons and neutrons, surrounded by electrons in specific orbitals. Aluminum has 13 protons and 13 electrons, which is why it is designated as element 13 on the periodic table. These electrons are distributed across different energy levels or shells, with three electrons in the outermost shell.
These outermost electrons, known as valence electrons, are not tightly bound to the nucleus, allowing them to move relatively freely. When aluminum atoms come together to form a solid, these free-moving electrons create what is often referred to as a &#;sea of electrons.&#; This sea of electrons is crucial for the material&#;s ability to conduct electricity.
To understand the electrical conductivity of aluminum, it is essential to grasp the concept of electric current. Electric current is the flow of electric charge, which can be carried by ions or electrons. In metals like aluminum, the charge carriers are the free electrons in the &#;electron sea.&#;
When a voltage is applied across a piece of aluminum, it creates an electric field that causes these free electrons to drift towards the positive terminal. This drift constitutes an electric current. The ease with which these electrons can move through the aluminum is a measure of its electrical conductivity.
The ability of aluminum to conduct electricity efficiently is due to the mobility of its free electrons. These electrons are not tightly held by the atomic nuclei, allowing them to respond quickly to an electric field. This movement of electrons enables aluminum to conduct electric current effectively.
Pure aluminum exhibits moderate electrical conductivity compared to other metals like copper and silver. It has a conductivity of approximately 37.7 million siemens per meter (MS/m), which is lower than that of copper (58 MS/m) but still sufficient for many electrical applications.
The following table lists the electrical conductivity of other aluminum alloys:
Type/AlloyElectrical Conductivity (MS/m, 20°C)RemarksAluminum-Copper Alloys (2XXX Series)30.0-40.0Electrical conductivity varies depending on copper content, suitable for some special electrical applicationsAluminum-Manganese Alloys (3XXX Series)30.0-35.0Good workability and corrosion resistance, moderate electrical conductivityAluminum-Silicon Alloys (4XXX Series)25.0-30.0Primarily used for casting, lower electrical conductivityAluminum-Magnesium Alloys (5XXX Series)30.0-35.0Good corrosion resistance, moderate electrical conductivityAluminum-Magnesium-Silicon Alloys (6XXX Series)32.0-37.0Used in automotive and building applications, higher electrical conductivityAluminum-Zinc Alloys (7XXX Series)20.0-25.0Primarily used in aerospace, lower electrical conductivityOther Aluminum Alloys (8XXX Series)25.0-35.0Specific applications, electrical conductivity varies depending on alloy compositionAnodizing is an electrochemical process that enhances the surface properties of aluminum. It involves creating a controlled oxide layer on the metal&#;s surface, which can improve corrosion resistance, durability, and even aesthetics. However, anodization affects the electrical conductivity of aluminum.
Initially, during anodization, the surface of aluminum develops a porous oxide layer, which is non-conductive. This layer can be further treated or sealed to achieve desired properties. While pure anodized aluminum has a significantly lower electrical conductivity than raw aluminum due to this insulating oxide layer, the exact conductivity depends on the thickness and type of anodization.
The conductivity of anodized aluminum oxide is much lower than that of pure aluminum or aluminum alloys that have not been anodized. The specific conductivity value depends on the thickness and density of the oxide film, but is usually much lower than the 37.7 MS/m of pure aluminum (at 20 ° C).
Electrical Conductivity of Anodized Variants:
During the anodizing process, the formed oxide layer is very thin and non-conductive, which requires aluminum to consider the loss of conductivity in electronic applications. After surface treatment such as anodizing or powder spraying, the conductivity of different types of aluminum will decrease. Anodizing can produce oxide layers with different thicknesses and properties, thereby affecting the electrical conductivity of the final product. In contrast, although powder spraying does not form a completely isolated oxide layer on the aluminum surface, it still has a certain degree of impact on the conductivity.
Untreated or lightly treated aluminum is usually preferred in electronic devices to ensure good electrical conductivity. In external applications that require corrosion resistance and environmental protection, anodizing or powder spraying is more preferred to enhance the durability and appearance of aluminum.
To measure the conductivity of aluminum, first, a known current is passed through an aluminum sample. Next, probes are used to measure the voltage drop across the sample. With these measurements and the sample&#;s dimensions, the conductivity can be calculated using the following formula:
Conductivity (σ) = (Current (I) × Length (L)) / (Voltage Drop (V) × Cross-sectional Area (A))
Where σ is the conductivity in Siemens per meter (S/m), I is the current in amperes (A), L is the length of the sample in meters (m), V is the voltage drop in volts (V), and A is the cross-sectional area of the sample in square meters (m²).
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Wide Applications of Aluminum as an Electrical ConductorAluminum has gained widespread application as an electrical conductor, particularly in the power industry, where it has demonstrated its unique advantages. On high-voltage power poles, engineers and workers frequently encounter aluminum conductors due to its notable benefits over other materials.
In recent years, aluminum has also gained popularity in residential, aircraft, building, and household appliance applications. For instance, aluminum wires are often used to replace traditional copper wires in home electrical circuits, reducing the weight and cost of wiring. In aircraft manufacturing, aluminum conductors&#; lightweight nature makes them ideal for connecting various electrical circuits and systems. In buildings, aluminum busbars are used to distribute power to different circuits and floors, meeting the electrical needs of the structure.
Comparing Aluminum Electricity Conductivity to Other MetalsHere&#;s a comparative table of electrical conductivity for aluminum and some other commonly used metals:
MetalElectrical Conductivity (MS/m)Aluminum37.7Copper58.0Silver63.0Gold45.0Brass15.9 &#; 28.0Iron (pure)10.0Steel (low carbon)6.99Zinc (pure)16.6Nickel (pure)14.0Note: Electrical conductivity is typically measured in units of million siemens per meter (MS/m) or mega siemens per meter (MS/m).
This table shows that aluminum has a good conductivity, though it is lower than that of copper and silver, which are known for their excellent conductivity. However, aluminum&#;s lower cost and lighter weight often make it a preferred choice for various electrical applications where high conductivity is not the sole consideration.
Copper remains the primary choice for electrical conductors for several reasons, including its superior ductility, appealing golden-brown finish, and enhanced strength and hardness. However, its most significant advantage is its superior electrical conductivity compared to aluminum. This superiority is primarily due to copper&#;s lower resistance to electric current.
Electrical resistance measures how much a material opposes the flow of electric current. Materials with high resistance, such as plastic or rubber, are known as insulators. While all materials have some resistance, metals typically exhibit very low resistance, making them good conductors of electricity.
Resistance depends on two factors: the dimensions of the conductor and a material-specific property known as resistivity. Resistivity is an intrinsic property that quantifies how strongly a given material opposes the flow of electric current. When comparing copper and aluminum conductors of equal length and cross-sectional area, copper demonstrates higher conductivity due to its lower resistivity.
The resistivity of copper is lower than that of aluminum. Specifically, copper has a resistivity of approximately 1.68 x 10^-8 ohm-meters, while aluminum has a resistivity of about 2.82 x 10^-8 ohm-meters. This lower resistivity in copper means that it offers less opposition to the flow of electric current, allowing electrons to move more freely and efficiently through the material.
On a microscopic level, copper&#;s superior conductivity is also due to the behavior of its free electrons. Free electrons in copper are less likely to encounter a phenomenon known as phonon collision. Phonon collisions occur when vibrating atoms within a material create mechanical energy that interferes with the movement of electrons. These collisions increase the material&#;s resistance to electric current.
Despite aluminum having a higher concentration of free electrons than copper, these electrons are more prone to phonon collisions. This increased scattering of free electrons in aluminum contributes to higher resistance and, consequently, lower conductivity compared to copper.
Experimental data confirms that copper is a better conductor than aluminum. The free electrons in copper experience fewer phonon collisions, enabling a more efficient flow of electric current. In contrast, the free electrons in aluminum encounter more interruptions, leading to increased resistance.
Due to its lower resistivity and fewer phonon collisions, copper is the preferred material for many electrical applications. Its high conductivity makes it ideal for wiring in homes, buildings, and electronic devices, where efficient and reliable electrical performance is critical. Additionally, copper&#;s ductility allows it to be easily formed into wires and cables, enhancing its practicality in various applications.
ConclusionIn conclusion, while raw aluminum possesses moderate electrical conductivity suitable for many applications, anodization alters its surface properties, including conductivity. Understanding the conductivity of aluminum, whether raw or anodized, is crucial for leveraging its properties effectively across industries where both electrical performance and material durability are critical.
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FAQWhat are aluminum electrical cables made of?Aluminum electrical cables are primarily made of aluminum alloys, including pure Electrical Conductor grade aluminum, alloy , and aluminum . Some cables, like ACSR and ACAR, combine aluminum alloys with steel or aluminum alloy cores for added strength. AAC is often used in urban distribution, while AAAC is noted for its corrosion resistance. ACSR is popular for transmission and distribution due to its steel core, and ACAR offers improved electrical and mechanical properties but is more costly.
What applications most commonly rely on aluminum as a conductor?Aluminum is widely used in electronics and electrical products due to its lightweight, conductivity, and cost-effectiveness. It&#;s commonly found in overhead transmission lines, electrical components like connectors and casings, and heatsinks for efficient heat dissipation.
How Do Aluminum Grades Affect Electrical Conductivity?Aluminum grades, ranging from the series to the series, vary in their electrical conductivity due to differences in alloy composition and treatments. The purest form, series (EC-grade aluminum), achieves approximately 61% IACS conductivity, ideal for applications requiring high electrical and thermal conductivity. Other grades like AA- and AA- also exhibit good conductivity, suitable for specific applications such as aluminum wiring and construction.
Is aluminium a good electrical conductor?Yes, aluminium is a good electrical conductor. While it is not as conductive as silver or gold, which are too expensive for regular use, aluminium is the second most conductive metal suitable for practical and industrial applications, next to copper. Its lightweight nature is a significant advantage, especially in industries where weight reduction is crucial, such as aerospace.
Do aluminium finishings impact electrical conductivity?Yes, aluminium finishings can indeed impact electrical conductivity. Generally, untreated aluminium offers better conductivity compared to aluminium with coatings or surface treatments like anodizing, which create an oxide layer that increases electrical resistance. Other coatings like paint or enamel can also affect conductivity.
Why is conductivity important in aluminium?Conductivity is important in aluminium because it affects power transmission efficiency, wiring applications, industrial uses, electronics, heat dissipation, and cost-effectiveness due to its lightweight nature. Efficient conductivity ensures less energy loss, improved performance, and safer operations.
Catalog: Materials Guide
This article was written by engineers from the BOYI team. Fuquan Chen is a professional engineer and technical expert with 20 years of experience in rapid prototyping, mold manufacturing, and plastic injection molding.
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