Heat shield

A heat shield is designed to protect an object from overheating by dissipating, reflecting or simply absorbing heat. The term is most often used in reference to exhaust heat management and to systems for dissipation of heat due to friction. A heat shield is designed to protect an object from overheating by dissipating, reflecting or simply absorbing heat. The term is most often used in reference to exhaust heat management and to systems for dissipation of heat due to friction. Heat shields protect structures from extreme temperatures and thermal gradients by two primary mechanisms. Thermal insulation and radiative cooling, which respectively isolate the underlying structure from high external surface temperatures, while emitting heat outwards through thermal radiation. To achieve good functionality the three attributes required of a heat shield are low thermal conductivity (high thermal resistance), high emissivity and good thermal stability (refractoriness). Porous ceramics with high emissivity coatings (HECs) are often employed to address these three characteristics, owing to the good thermal stability of ceramics, the thermal insulation of porous materials and the good radiative cooling effects offered by HECs.