Rheocasting is Cool

For some, this might sound like a bold statement. But let me explain. A Rheocasting slurry is way cooler than the liquid melt. Still, a Rheocasting slurry keeps its temperature for a long time. This can be used to fill the cavity at a lower speed and with laminar flow. This enables better filling of the cavity, lower porosity and better mechanical properties.

But why does the slurry keep its temperature? This has to do with the latent heat. Latent heat is energy released or absorbed by a body or a thermodynamic system during a constant-temperature process, usually a first-order phase transition. So if the liquid aluminium solidifies, the energy difference between the liquid and the solid state is spread into the surrounding area. For melting, energy is taken from the surrounding area.

To show you that effect, I recorded ice melting in the video below. See for yourself how the temperature stays level for half an hour. As soon as most of the ice melts, the temperature increases rapidly.

The Rheocasting slurry works with the same principle. A slurry is made of a mixture of liquid metal and already globular solidified metal. But be aware not all Rheocasting methods will enable you to generate a homogeneous and consistent slurry. I recommend the Comptech Rheometal process because it is the only one that is not temperature-regulated.

Back to the slurry. The globular solid particles are a point of solidification of the liquid melt. The latent heat of the solidification heats up the surrounding metal. Therefore enabling it to flow even further.

That’s why Rheocasting is cool!

For more information on the flow behaviour, see the article on the pocket warmer effect. If you are ready to learn what Rheocasting can do for your foundry, schedule a free consultation below.