To: Different Aluminum Purity Levels Explained

Different Aluminum Purity Levels Explained

Aluminum is one of the most versatile and widely used metals in the world. From construction to aerospace industries, it has made a significant contribution to modernization. But have you ever wondered what makes different grades of aluminum unique? In this blog, we will dive deeper into the concept of aluminum purity levels and what they mean for various industries. We will also discuss the characteristics of high purity aluminum, common levels of aluminum purity, and how each level is achieved. Lastly, we will explore the utility of different purity levels in various industries such as aerospace, construction, heavy equipment manufacturing, and semiconductor production equipment. Join us as we uncover all there is to know about different aluminum purity levels.

aluminum purity levels

Understanding Aluminum Purity Levels

Different levels of aluminum purity have a significant impact on the properties and applications of the metal. Commercial grade pure aluminum is generally 99.0% (1100) minimum aluminum content, and this base pure aluminum grade is sufficient for producing the alloys required for the vast majority of aluminum applications such as for Cans, Coils, Extrusions, Packaging, and Plate since the cost is relatively low and this base grade is quite abundant.  

However, there are more specialized applications that require higher purity aluminum, such as 99.99% minimum (4N), with significantly less impurities and which applications can justify the significantly higher price due to the higher cost of producing compared with standard grade aluminum.  While 1100 is the common grade assigned by the Aluminum Association for 99.0% minimum purity, 1199 is the grade assigned to designate 99.99%.  However, since the Aluminum Association does not distinguish between the higher purities beyond 99.99%, the common terminology used to distinguish high purities is using a number followed by N, for nine.  Thus 4N6 would be 99.996% minimum purity and 6N would be 99.9999% minimum purity.  Throughout our website and articles, we will use these two types of designations interchangeably.  

High purity aluminum, with minimal impurities, exhibits excellent properties and is crucial in various critical industries. The varying levels of purity directly influence the strength, electrical conductivity, and corrosion resistance of aluminum, making it essential to understand these levels for selecting the appropriate material for specific applications. By comprehending the implications of aluminum purity levels, manufacturers and engineers can make informed decisions when choosing aluminum for diverse uses.

The Concept of Aluminum Purity

The absence of impurities in aluminum determines its purity level, crucial for enhanced properties and performance characteristics. Different aluminum purity levels are designated based on impurity concentration, ensuring quality and reliability. Higher purity aluminum exhibits superior properties attributed to minimal impurities. The percentage of pure aluminum content defines its purity, impacting strength, conductivity, and corrosion resistance. Understanding these levels aids in selecting the right aluminum grade for specific applications.

Differentiating Aluminum Grades

When categorizing aluminum grades, purity, alloying elements, and properties are the key factors. Assessing purity, strength, and corrosion resistance aids in distinguishing between aluminum purity levels. Each grade is tailored to specific industry needs, catering to different performance criteria. Understanding these distinctions helps in selecting the most suitable material for various applications, including the 6000 grades of aluminium which are known for their magnesium and silicon content. This knowledge is essential for informed material selection, ensuring optimal performance in diverse uses.

Does a higher level of aluminum purity always mean better quality?

No, a higher aluminum purity level does not always mean better quality. While high aluminum purity levels are important for certain applications, other factors such as alloy composition, manufacturing processes, and intended use also play a significant role in determining the overall quality of aluminum products.

Characteristics of High Purity Aluminum

Exceptional electrical and thermal conductivity are characteristic of high purity aluminum, making it widely sought after for applications requiring efficient energy transfer. Its high corrosion resistance deems it suitable for critical applications, especially in corrosive environments. With its low density, pure aluminum is ideal for lightweight applications, contributing to the development of durable yet lightweight products. In fact, pure aluminum is often used as a material for reflectors and other applications where lightweight materials are used, making it an effective reflector of heat as well as visible light. Even at high temperatures, high purity aluminum maintains its mechanical properties, ensuring reliability in various operating conditions. Additionally, the higher melting point of high purity aluminum sets it apart from alloys with impurities, further enhancing its suitability for demanding applications.


Physical Properties

High purity aluminum displays exceptional thermal and electrical conductivity, making it ideal for various industrial applications. Its low density contributes to its lightweight nature, ensuring ease of use in manufacturing processes. The excellent corrosion resistance of high purity aluminum further enhances its durability and longevity, especially in harsh environments. Additionally, aluminum with high purity maintains its mechanical properties even under extreme temperatures, showcasing its reliability across a wide range of conditions. Moreover, the high melting point of pure aluminum signifies its thermal stability and resilience, making it a preferred choice for applications requiring durability and strength.


Chemical Properties

High purity aluminum, with its protective oxide layer, exhibits enhanced resistance to corrosion, thanks to its chemical properties and atomic number. It can withstand harsh environments and offers exceptional stability, devoid of impurities. This makes it an ideal choice for critical applications due to its chemical stability, resistance to chemical reactions, environmental factors, and its atomic number. These properties make high purity aluminum a preferred option for applications that demand reliability and durability in challenging conditions.


Impact of Performance

High purity aluminum significantly enhances the effectiveness and dependability of applications. The level of purity directly impacts the mechanical strength and conductivity of aluminum, influencing its overall performance. Moreover, aluminum purity plays a significant role in determining the corrosion resistance and durability of components, making it crucial for specific industrial applications. Achieving high purity aluminum is essential for ensuring consistent and reliable performance across various uses. By maintaining high purity levels, the metal's performance can be optimized to meet industry standards and specific application requirements.


Common levels of aluminum purity

Understanding the common aluminum purity levels is essential for selecting the right material to meet specific industrial needs. These levels of aluminum purity accommodate a wide range of industry-specific demands, serving diverse requirements effectively. The purity level directly influences the material's strength, conductivity, and corrosion resistance, making it crucial for achieving consistent and reliable performance in various applications. For example, a base metal with a sum of all targeted impurities equal to 10 ppm will have a purity of 99.999%, or 5N ("five Nines"). 


High Purity Aluminum - 99.99% (4N) to 99.996% (4N5)

99.99% and 99.996% are the highest aluminum purities possible with standard aluminum production, although this is limited to only a few primary aluminum smelters around the world since it depends on specific reduction technology and specific alumina raw materials.


High Purity Aluminum - 99.999% (5N) to 99.9995% (5N5)

High purity aluminum, with a purity level of 99.999% (5N) or higher are produced with 99.99% or 99.996% as the starting raw material, using an additional refining process that is quite costly and generates much of the original aluminum as waste to result in purer and purer aluminum.  The process is increasingly costly the purer the process produces since it takes more time and more aluminum is discarded as waste during the process. 

Its applications in electronics, aerospace, and other high-tech industries are prominent due to its superior corrosion resistance and better electrical conductivity. However, the higher the purity, the higher the cost, making it more expensive than lower purity levels. This form of aluminum is crucial in environments requiring materials to withstand corrosive elements or extreme temperatures, making it ideal for applications in cryogenic temperatures. When compared to common metals, high purity aluminum exhibits heightened electrical conductivity, making it a valuable material for various industries. At this purity, aluminum serves chiefly as an electrical conductor, where it delivers nearly twice the effective conductivity as copper on a weight-for-weight basis.


Ultra Pure Aluminum - 99.9999% (6N) to 99.99995% (6N5)

Ultra pure aluminum, with a purity level ranging from 99.9999%(6N) to 99.99995% (6N5), finds extensive application in scientific and industrial sectors requiring exceptional conductivity and corrosion resistance. Processes such as vacuum distillation and zone refining are utilized for its production, contributing to its premium pricing compared to lower purity grades. Common applications include semiconductors, electronic where the unparalleled purity and conductivity of ultra pure aluminum are indispensable. This advanced grade of aluminum plays a critical role in upholding operational efficiency and longevity in diverse technological settings.  

The production of materials with a purity level of 99.99995% (6N5) is an intricate and costly process, primarily due to the advanced techniques and rigorous standards required to achieve such high purity. This level of refinement is primarily used in specialized applications like Molecular Beam Epitaxy (MBE). MBE is

 a highly sophisticated method used in the fabrication of semiconductor devices and materials research, where the slightest impurities can significantly impact the final product's performance. The extraordinary purity of 6N5 materials is essential in MBE applications to ensure the precise control of the composition and structure of the materials being developed, which is crucial in creating high-quality semiconductor layers. The demand for such high purity levels, while critical, adds to the complexity and expense of the production process, reflecting the significant investment in technology and expertise required to produce materials at this standard.


Process of Achieving High Purity Aluminum 

Achieving high purity aluminum necessitates the meticulous elimination of impurities and precise control over alloying elements. Various purification techniques, such as electrolysis and fractional crystallization, are employed to enhance aluminum's purity level. The extraction and refinement methods play a crucial role in obtaining high purity aluminum. This process involves meticulous control over impurity levels, alloying elements, and even the presence of alpha rays. The ultimate goal is to produce aluminum with significantly reduced impurities and enhanced purity.


Extraction and Refinement

The process of extracting aluminum involves the purification of bauxite ore to acquire high purity aluminum oxide. This purification is essential to ensure the removal of impurities and alloying elements from the aluminum. Techniques such as the Hall-Héroult process play a crucial role in refining aluminum, contributing to the production of high purity aluminum. Attaining high purity aluminum requires strict control and precision in the extraction and refinement procedures. The elimination of impurities in these stages is paramount in determining the ultimate purity and quality of aluminum.


Aluminum Purification Techniques

Aluminum purification techniques involve various methods to achieve high purity levels. Fractional crystallization is used to aid in the process and ensure the removal of impurities, resulting in higher strength aluminum. Electrolysis plays a crucial role in separating impurities from aluminum, contributing to its purity. These precision techniques include the removal of alloying elements to enhance aluminum properties and make it suitable for a wide range of applications. Additionally, cryogenic temperatures are employed in some purification processes to achieve the required purity levels, meeting industry standards and ensuring optimal performance.


Utility of Different Purity Levels

Various purity levels of aluminum serve diverse industry needs and offer specific mechanical and electrical properties. These levels play a crucial role in fulfilling industry-specific performance demands by allowing tailored material properties across applications. The utility of different purity levels effectively addresses industry-specific requirements, catering to applications like aerospace, construction, heavy equipment manufacturing, and semiconductor production equipment. High purity aluminum, with its higher strength and resistance to corrosion, serves well in applications requiring durability, while lower purity levels find use in general-purpose applications. By ensuring the right aluminum properties, such as conductivity and resistance to cryogenic temperatures, different purity levels enable the production of aluminum products suitable for various industries while meeting specific performance and regulatory requirements.



High-purity aluminum is used in batteries to ensure efficient and uncontaminated reactions, particularly in aluminum-air batteries and as anode materials in some lithium-ion batteries.



Is used in cryogenic applications for its low-temperature properties, such as superconductivity, to create specialized equipment and components.



High-purity aluminum is employed in electronics as a material for wiring, interconnects, and circuitry due to its excellent electrical conductivity and reliability.


Medical Imaging

Is used in medical imaging equipment, such as X-ray machines and MRI scanners, as structural components and shielding to enhance imaging precision and safety.


Quantum Computing

Can be used in quantum computing systems as a substrate material for superconducting qubits due to its low-temperature properties and high electrical conductivity.


Medical Imaging

High-purity aluminum is utilized as a sputtering target in thin-film deposition processes to create precise and high-quality aluminum thin films for various applications, including optics and electronics.


Thin Film Coatings

Is used to create thin film coatings through techniques like physical vapor deposition (PVD) or chemical vapor deposition (CVD) for applications in optics, electronics, and corrosion resistance.


Vapor Deposition

High-purity aluminum is employed in vapor deposition processes to create thin, uniform aluminum layers on surfaces, enhancing their properties for specific applications, such as reflective coatings and protective barriers.



To summarize, the purity level of aluminum has a significant impact on its physical and chemical properties, as well as its performance in various industries. Understanding the concept of aluminum purity and differentiating between grades is crucial for selecting the right material for your specific application. High purity aluminum offers exceptional characteristics that make it suitable for aerospace, construction, heavy equipment manufacturing, and semiconductor production equipment. Achieving high purity levels involves extraction, refinement, and aluminum purification techniques. 

If you require high purity aluminum (99.99% or higher) purities for your business needs, please reach out to us for a quote and explore the options available to you.  We have the broadest range of aluminum high purities and high purity alloys, as well as one of the largest product varieties.  If we don’t have in stock, we can generally custom produce within 3 to 4 weeks.  Our team of experts will guide you in making the best choice for your requirements.