GB656503A - Improvements in or relating to members to be used in heat engines - Google Patents

Abstract

656,503. Turbine blades. SOC. NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIATION. Oct. 26, 1948, No. 27846. Convention date, Oct. 27, 1947. [Class 110(iii)] [Also in Groups II and XXII] A member capable of withstanding mechanical stresses at high temperatures such as a gas turbine blade, a combustion chamber for a heat engine, a hot gas pipe &c. is characterized in that a metal core a is coated at least on its exposed surface with alternate adhesive refractory layers of enamel c and metal m<SP>1</SP>, m<SP>2</SP>. In one embodiment a gas turbine blade comprises a core a and root t of highly refractory alloy, e,g. nickel-chrome austenitic steel. The core, after pickling the surface, is coated with nickel m<SP>1</SP> by electrolytic deposition and the nickel coating is covered with a layer e of zirconium oxide enamel enriched with other refractory oxides, e.g. molybdenum oxide, vanadium oxide, tungsten oxide. The layer e is deposited by atomization and then baked and glazed with a zirconium oxide enamel minus the refractory oxides. Finally, the layer e is covered with a layer m<SP>2</SP> of chromium deposited by electrolytic means. The enamel layers increase their refractory properties by the inclusion of 'larger proportions of refractory. oxides the further they are from the core a. At the root t the metal layer m<SP>2</SP> adheres directly to the core a thereby forming a closed heat conducting circuit. To improve,. adhesion of the layers e and m<SP>1</SP>, fritted enamel, crushed without the refractory oxides but charged with nickel and bismuth ions, may be sprayed on the layer m<SP>1</SP> at the beginning of the atomization. The term " enamel" includes glass, glassware glaze, metal enamels, ceramic varnish, enamel or glaze, ceramic paste or a mixture of these compositions. The enamel layers may be applied with a brush, or by spraying, or by powdering with a blower or by lithographic printing. The metal layers may be iron, chromium, nickel, cobalt, platinum or other refractory metals or alloys or metals in combination with non-metals. The metallic layers may be deposited by plating methods such as electrolysis, chemical displacement and the like.