Effects of Impurities on the Performance of Aluminum
Aluminum is one of the most widely used metals in the world today. It is recognized for its corrosion resistance, thermal and electrical conductivity, and light weight. Aluminum is used primarily in the manufacture of automobiles and aircraft, but is also used in many other sectors including construction, electronics, and energy production. The performance of aluminum is strongly affected by the presence of impurities, which can be introduced during either production or subsequent processing.
During its production, aluminum is sourced from both bauxite ore and recycled scrap. Impurities can be inadvertently introduced into the aluminum during the production process. Trace elements, such as iron, phosphorus, silicon, and titanium, can be brought into the material from the ore, scrap, or the production environment. Similarly, impurities can be inadvertently introduced during scrap re-smelting or secondary processing operations. These impurities can significantly affect the physical properties and performance of the aluminum.
When present in low concentrations, impurities in aluminum can have a beneficial effect on performance. Iron and phosphorus, for example, are known to improve the tensile strength of aluminum, while silicon can improve weldability. However, impurities can become deleterious at higher concentrations, potentially affecting the strength, ductility, weldability, and corrosion resistance of the material. Iron, in particular, is known to be particularly detrimental, with concentrations of over 0.03% having a negative impact on the mechanical properties of aluminum.
Impurities can also be detrimental during further processing operations. During casting, for example, impurities can lead to inadequate and weakened structures as well as difficulties in die casting and machining. Impurities can also reduce a metal’s ability to be polished, causing staining and other surface defects. Impurities also reduce the ability of the aluminum to be anodized, resulting in reduced performance and potentially an unacceptable finish.
Finally, impurities can reduce the electrical and thermal conductivity of aluminum, reducing its performance and suitability for certain applications. This can be particularly problematic for components and products used in the electronics and energy sectors which require extremely high levels of conductivity.
It is therefore essential to ensure aluminum is free from impurities, in order to optimize performance and ensure it is suitable for the end application. The elimination of impurities during production can be achieved through the adoption of practices such as degassing and refining, and the materials being produced should undergo rigorous testing to ensure they meet the specifications required by the end user.
In conclusion, the presence of impurities in aluminum can have a significant effect on performance. Impurities can be introduced during production, or during further processing, and can lead to reduced strength, weldability and corrosion resistance, as well as decreased electrical and thermal conductivities. Therefore, it is essential to ensure that aluminum is free from impurities, as far as possible, to ensure it meets the necessary performance requirements for its intended application.
