Porous silicon carbide foam as electrical heater

Silicon carbide is electrically semi conductive. Its use as electrical heating element has been well known for more than 50 years. Therefore it is not surprising that foams made of silicon carbide can be used as electrical heaters as well. The different applications of heating elements demand a specific design of the elements themselves. The ruling parameters are the specific electrical resistance of the heater material, the maximum thermal load, the specific power per surface area and the required geometry of the heating element. Ceramic foams are easy to penetrate and flush by liquids and gases since their open porosity can reach 90 vol%. The foam structure enables an intense contact of the bypassing medium to the solid struts of the foam. Therefore an efficient heat transfer from the foam heating element towards the medium which is supposed to be heated up is achieved. Further advantages of foam heating elements are rapid heating ramps, outstanding thermal shock behavior, high thermal load and simple manufacture. This paper intends to demonstrate some principal features of ceramic foam heating elements including some experimental results of basic foam heaters and the principal route of manufacture.