| 摘要 |
On the one hand is provided an electric heating element (15, 31) consisting of a semiconducting ceramic (28, 32) as well as a method for its production. The semiconducting ceramic material may be porous or foamed to thus contain pores (29, 34) open outwardly. The pores are attainable by admixing filler bodies, which dissolve during sintering, to the starting material or by impreganting a textile substrate material (36) with a ceramic material. Due to the porosity of the heating element (15, 31) an increased radiant surface area is attained. On the other hand is provided an electric heating element (115, 132, 145, 150, 158, 160, 162) as well as a method for its production which consists of semiconducting ceramic and comprises a negative temperature coefficient of the electrical resistance. The temperature coefficient is negative throughout over the full operating temperature range. The material suitable for the heating element (115, 132, 145, 150, 158, 160, 162) is doped silicon carbide or TiN. One such heating element (115, 132, 145, 150, 158, 160, 162) may be put to use, for example, rod-shaped in a radiant heater body (111) or foil-shaped at the underside of a surface element (30) of a cooktop (31). The electric conductivity of the material of the heating element (115, 132, 145, 150, 158, 160, 162) can be adjusted by nitrogen absorption during annealing in a nitrogen atmosphere subsequent to the sintering process. |
