A more than 50 percent improvement in the thermal conductivity of aluminium casting alloy was achieved. Typical thermal conductivity of aluminium casting alloy is 120 W/mK. In the programme the value of 207 W/mK was achieved. The result is novel, unique and internationally very significant.
According to the results optimization of alloy composition and thermal history (heat treatment) are the most important factors affecting thermal conductivity. Reducing the amount of silicon in the aluminium alloy improves thermal conductivity. There is a sharp decrease in thermal conductivity as silicon concentration of the base aluminium alloy is increased to about 3%.
In addition increasing of the heat treatment temperature increases the thermal conductivity of die casting alloys considerably. By heat treatment up to 520 oC, an increase of 40-50% in thermal conductivity is obtained. Melt treatments do not affect the thermal conductivity appreciably.
The achieved result increases the thermal conductivity of aluminium die cast and solves castability requirements such as fluidity, hot cracking and also sticking and soldering of high pressure die casting process.
In electronic and electro-technical applications the demands for the heat removal properties are increasing. Electronic components are becoming more powerful and produce excess heat. Thus, there is more waste heat to be removed from the apparatus.
Cast products are losing positions against extruded profiles or other solutions due to material and manufacturing based issues. Foundry allows normally have lower thermal conductivity. In addition, normally cast material has more micro porosity. Some customers want to replace extrusions with cast heat sinks because of other advantages cast product can offer.
Both researchers and industry are very excited with the results. More efficient electrical and thermal conductivity, thinner casing walls, die cast part is cheap to manufacture, transport and install, good corrosion resistance and excellent surface quality.
The results of the work can be utilized when making aluminium cast parts with improved thermal conductivity and high heat dissipation capacity. There are numerous applications, for example, electronic housings, base stations, heat sinks, inverters. These unique results will have an impact in
many other applications as well. Improvement in heat transfer guarantees not only high-performance of devices, but also longer life time and significant energy and cost savings.
Based on achieved results and increased competence Alteams was able obtain a new business segment where heat dissipation is the key driver. Deliveries of these new applications have been started already. Two main telecom customers of Alteams perform at the moment testings of the cast products with improved thermal conductivity.
Kimmo Pesonen, Alteams Oy
Alteams Oy, Aalto Engineering