Thermal conductivity of refractory coatings for foundry applications

In this work, three different kind of coatings varnishes are tested. These coatings are deposited on a metallic substrate and the thermal diffusivity is evaluated by one side thermal test. The laser shots the surface of the coating with a short pulse and the temperature variation is measured by an infrared camera. Knowing the density, and measuring the specific heat by Differential Scanning Calorimeter, it is then possible to derive the value of the thermal conductivity.

In the foundry industry the typical casting process is done by pouring the liquid (fused) metal on a mold shape and left until solidification. The inner part of the mold gets in contact with the liquid, high temperature metal. The mold is generally coated with a special refractory varnish that improves the flow of the liquid metal inside the mold and allows to obtain smoother surfaces of the solidified object. In the process of optimizing the performance of such refractory coatings, new recipes are experimented and the thermal properties of such new materials are paramount in the process of qualification of the product.