Abstract: A low thermal conductivity heat barrier composition, particularly for a superalloy article, is disclosed comprising a zirconia base and a dysprosium oxide having the dual function of stabilizing the zirconia and reducing the thermal conductivity thereof. Optionally, the composition also comprises a metal oxide containing a quadrivalent metallic ion selected from the group consisting of hafnium dioxide, cerium dioxide, uranium dioxide, and mixtures thereof.

Abstract: A process for producing a coating for protecting superalloy articles against high temperature oxidation and hot corrosion comprises forming, on the surface of the article, a first deposit of an agglomerated powdered alloy containing at least chromium, aluminum and an active element, and filling the open pores of the powder deposit by a second, electrolytically applied, deposit of a precious platinum group metal. An appropriate thermal treatment is then carried out to effect interdiffusion between the powder based deposit and the electrolytic deposit and produce a coating including chromium, an active element such as yttrium, and a precious platinum group metal throughout its thickness.

Abstract: The sealing composition contains powders composed, by weight, of 70 to 90% of aluminium, 5 to 25% of silicon, 0 to 5% of silica and 0.1 to 5% of moderating metal, which are dispersed in a vehicle comprising an organic binder dissolved in a solvent and a mineral binder.It is applied to the faces to be assembled of a ceramic part and of a refractory alloy or superalloy part and the whole is heated in order to eliminate said vehicle and form between the two parts a layer of mullite syncrystallized with the ceramic.

Abstract: A surface layer of a material containing carbon and/or a carbide is produced on the outer surface of a solid carbon-based substrate (1) by selective application of material, said surface layer adhering strongly to the substrate, having a high specific surface area and having open pores (5) of a depth of at least 1 nm, and a metal material having a strong affinity for carbon, comprising at least one metal chosen from cerium, cobalt, chromium, iron, hafnium, iridium, osmium, palladium, platinum, rhodium, ruthenium, lanthanum, manganese, molybdenum, nickel, silicon, tantalum, thorium, titanium, uranium and tungsten, is deposited on said surface layer, substantially filling said pores.The metal deposit (8) may be rectified and polished without peeling off, in order to produce a mirror of low inertia.

Abstract: The bath contains an oxalate of the metal or of each of the metals to be deposited and hydrazine as a reducing agent, together with ethylenediamine as a complexing agent and at least one stabilizing agent, said bath being highly basic and having an autocatalytic effect.

Abstract: A method including aluminization treatment preceded by a palladium predeposition treatment, the palladium being associated with at least one barrier metal selected from nickel, cobalt, and chromium, thereby avoiding hydrogen occlusion.