GB737058A - Method of manufacturing heating conductors for electric heating apparatus - Google Patents

Abstract

737,058. Coating with metals. WURTTEMBERGISCHE METALLWARENFABRIK. Sept. 2, 1953 [Sept. 2, 1952], No. 24314/53. Class 82 (2). [Also in Groups XI and XXIII] Electrically heated articles such as frying-pans or baking- or boiling-vessels have walls 1 of insulating material such as porcelain or of metal covered with enamel 2 on which are deposited metal strips 3 forming heating resistances by condensation of metal vapour or cathodic sputtering in vacuo. The insulating walls are heated and are covered by a stencil with openings giving the required pattern, e.g. a spiral or zigzag line to the deposit, which may be a noble metal, e.g. gold. Contact portions 4 of the strips 3 are thickened with metal by applying further metal through a second stencil, and by applying a metallic burning-in paste, or by insetting or fusing small metal plates into the insulating support, preferably before deposition of the metal strip which is of uniform thickness. The insulating surface may be roughened by etching or may carry an insulating layer improving adhesion of the metal strip. The metal strip 3 after deposition may be burnt into the insulating strip at a temperature above its normal working temperature. The strip 3 may be embedded or covered by a screening insulating or protecting layer 6, e.g. of enamel entirely covering the support and strip except at the contact surfaces 4. The enamel is one in which the alkali oxides have been replaced by oxides of lower ionic conductivity (see Group XXIII). A contact arm 5 is provided.