Aluminum alloys for 3D printing of heat exchangers

Advances in 3D printing technology have changed the way heat exchangers are manufactured. Complex and free designs that cannot be realized by traditional manufacturing routes can be easily realized through 3D printing. Improved heat exchange efficiency and reduced weight, volume, and manufacturing costs are other advantages that 3D printing can offer. However, materials are another key consideration for heat exchanger 3D printing.

Recently, a leading domestic aluminum alloy 3D printing material manufacturer released a high thermal conductivity aluminum alloy 3D printing material to the market. The product is named HC 200 to show its ultra-high thermal conductivity of no less than 200W/(m·K).

The principle of metal heat conduction, materials and inherent defects of 3D printing

The essence of metal heat conduction is that there are freely movable electrons inside the metal. When a part of the metal receives heat, the energy of the free electrons in the heated part increases, the movement intensifies, and they constantly collide with metal ions to exchange energy, thereby transferring heat from one part to another. In order for metals to obtain higher thermal conductivity, it is necessary to require electrons to be "unimpeded" inside the metal, that is, there should be enough defects inside the metal material, and there should be less hindrance by impurities or other phases. This puts forward very high requirements on the composition control and preparation process of materials.

Among aluminum alloy materials, grades with high thermal conductivity (especially higher than 200) are very limited, and the most commonly used is 6063 aluminum alloy. 6063 is an AlMg series deformed aluminum alloy, the main alloying elements include Al, Mg, Cr, Cu, Si, etc. Its thermal conductivity is higher than 200 W/(m K), generally 210, and has a yield strength of not less than 160MPa and an elongation of 8% after T6 heat treatment. And 6063 has good plasticity and can be anodized, so it is the material of choice for various types of radiators. In other existing grades of aluminum alloy materials, the thermal conductivity is not higher than 200. Since pure aluminum does not contain other alloying elements, its thermal conductivity reaches 230W/(m·K).

Although 6063 aluminum alloy is a very good material, it cannot be directly used for metal 3D printing. The alloy is a deformed aluminum alloy, which is suitable for the casting process, but not suitable for the SLM selective laser melting 3D printing process with a high cooling rate. The final result is that when the 6063 alloy powder is printed by the SLM process, there will be large and small micro-cracks, and the material cannot be used. At present, some researchers try to make the 6063 alloys printable by modifying the composition or adding nano-phases and have achieved some results, but they have not been commercialized.

At present, AlSi10Mg material is widely used in the market. Although its thermal conductivity has reached a not-low 140W/(m·K), for applications requiring higher thermal conductivity, AlSi10Mg is powerless.

High-performance heat dissipation 3D printing aluminum alloy has made a breakthrough

In order to develop printable aluminum alloy 3D printing materials with high thermal conductivity and high performance, the domestic team has spent more than a year of independent research and development, and finally successfully realized the double two hundred (thermal conductivity exceeds 200 W/(m K) and tensile strength is higher than 200MPa) HC 200 high thermal conductivity aluminum material development. The following table is a comparison of the material properties of HC200, 6063, and AlSi10Mg:

With its ultra-high performance, this material is suitable for lightweight and complex structural or functional parts that have high requirements for heat dissipation and are especially suitable for the design and development of new heat sinks (especially micro-channel heat sinks). With innovative material solutions, coupled with the technical advantages of metal 3D printing, we hope to contribute to the product development of new radiators.

If you are interested in the HC 200 with medium and high thermal conductivity and high strength, JR has launched a printing service for high thermal conductivity aluminum. We look forward to cooperating with customers who are interested in printable high thermal conductivity aluminum solutions.