| 摘要 |
<p>A method of forming an electrical heating element in the form of an electrically non-conductive supporting body onto which an electrically resistive material is deposited, the method comprising the steps of preparing a dry metal powder of irregularly shaped metal particles of widely varying sizes, in the range 20-150 microns, roughening the surface of a supporting body onto which a heating element is to be formed, pre-heating said surface of the supporting body to a temperature within the range of 150-250 DEG C and flame spraying the dry metal powder onto said heated surface of the supporting body in a plurality of passes over the supporting body. The effective resistivity of the flame sprayed deposit is predetermined by adjusting the amount of oxidation on the surfaces of the metallic particles sprayed onto the supporting body. The amount of oxidation on the surfaces of the flame sprayed particles, and hence the resistivity of the sprayed deposit, can be varied by selecting the size range of the particles used, within said range of 20-150 microns. Alternatively the amount of oxidation on the surfaces of the flame sprayed particles can be varied by blending selected alloys into the powder to by sprayed such as to adjust the quantity of conductive oxides present on the sprayed particles.</p> |
