Abstract
High emissivity coatings have been used in industrial applications over 40 years with the goal of reducing the thermal losses in heating processes. By applying a high emissivity coating on the internal surface of a kiln lining, it is possible to increase the efficiency in heat exchange between the atmosphere and the walls, reducing the heat loss and also the fuel consumption. In general ceramic compounds such as cerium oxide, boron carbide, silicon boride, molybdenum silicide or chromium oxide are used as emissivity agents to obtain the desired thermo-optical properties in coatings. However, such compounds often prevent their application due to its high commercial value or its scarcity. In this context, this study aimed to evaluate the effects of iron chromite, an abundant mineral oxide and affordable commercial value in its use as emissivity agent in high emissivity refractory coatings. Through an indirect method of measuring emissivity, different coatings compositions with and without the addition of iron chromite were evaluated, in a comparative manner, aiming its application as coatings for refractory and insulation linings of industrial heating furnaces. With iron chromite additions of 7.5%, there was almost 8% increase in the emissivity of the coatings, suggesting their potential for this application.
Keywords:
high emissivity coatings; iron chromite
