Composites alumine-nickel à liant polyphosphate. Nouveau matériau pour éléments chauffants

Heating elements used below 1200°C are mainly metals. But metallic heating elements have a very low resistivity. So we propose a new material based on metallic particles dispersed in a ceramic matrix. In order to obtain и good dispersion and a low temperature processing, we used a polyphosphate binder. Owing to the enhanced oxidization of dispersed metals, this material is destined to heating elements working at a temperature below 700°C.We present the process of elaboration and the characteristics of the composite.The resistivity of such a composite material versus nickel content obeys a percolation law. A resistivity of 50 mΩ . cm has been obtained.Cold connections are realized by increasing the nickel concentration at the extremities of the heating element. The differences of shrinkage are compensated by the polyphosphate binder.