US Patent 6884967 Multi-layer ceramic heater element and method of making same

A ceramic heater element and a glow plug incorporating the novel heater element. The heater element has a base portion and a heater portion. Conductive, insulative and resistive layers extend through both the base and heater portions. An outer conductive layer is applied to the outside of the base portion to provide a highly conductive return path. This lends to limit the heating of the resistive layer in the base portion and results in better and more reliable heat concentration in the heater portion. The heater element is further provided with a waterproof non-electrically conductive outer layer. The heater element can be assembled to form a glow plug for a diesel engine.