Abstract: The invention relates to a ceramic thermal barrier composition of low conductivity and high high-temperature strength. In characteristic manner, the composition comprises a zirconia base, at least one trivalent oxide enabling the zirconia to be stabilized and enabling the thermal conductivity of the zirconia to be reduced in optimum manner, and at least one pentavalent oxide enabling the content of oxygen vacancies to be reduced so as to make it substantially equal to that of a partially stabilized zirconia. Preferably, said trivalent oxide is present with a molar content constituted by a first portion enabling the zirconia to be stabilized partially and a second portion which introduces point defects into the lattice said pentavalent oxide is present with a molar concentration equal to said molar concentration of said second portion of the trivalent oxide. The invention is applicable to making a superalloy machine part having a ceramic coating with said composition, and possibly also a bonding underlayer.

Abstract: The invention relates to a ceramic thermal barrier composition of low conductivity and high high-temperature strength. In characteristic manner, the composition comprises a zirconia base, at least one trivalent oxide enabling the zirconia to be stabilized and enabling the thermal conductivity of the zirconia to be reduced in optimum manner, and at least one pentavalent oxide enabling the content of oxygen vacancies to be reduced so as to make it substantially equal to that of a partially stabilized zirconia. Preferably, said trivalent oxide is present with a molar content constituted by a first portion enabling the zirconia to be stabilized partially and a second portion which introduces point defects into the lattice said pentavalent oxide is present with a molar concentration equal to said molar concentration of said second portion of the trivalent oxide. The invention is applicable to making a superalloy machine part having a ceramic coating with said composition, and possibly also a bonding underlayer.

Abstract: The invention relates to a ceramic thermal barrier composition of low conductivity and high high-temperature strength. In characteristic manner, the composition comprises a zirconia base, at least one trivalent oxide enabling the zirconia to be stabilized and enabling the thermal conductivity of the zirconia to be reduced in optimum manner, and at least one pentavalent oxide enabling the content of oxygen vacancies to be reduced so as to make it substantially equal to that of a partially stabilized zirconia. Preferably, said trivalent oxide is present with a molar content constituted by a first portion enabling the zirconia to be stabilized partially and a second portion which introduces point defects into the lattice said pentavalent oxide is present with a molar concentration equal to said molar concentration of said second portion of the trivalent oxide. The invention is applicable to making a superalloy machine part having a ceramic coating with said composition, and possibly also a bonding underlayer.

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: Apparatus for plasma activated chemical vapor deposition, the apparatus comprising a microwave-excited plasma reactor with a reaction enclosure (10), a microwave generator (20), a waveguide (21) providing non-resonant coupling, and insertion means (40-54) for inserting at least one flow of a predetermined gaseous mixture into the enclosure; the insertion means comprise, in order: transformation means (40-43) for transforming the state of a precursor of a material to be deposited to bring it to the gaseous state, feed means (41, 42) for feeding a vector gas suitable for being charged with the gaseous precursor to constitute the above-mentioned predetermined gaseous mixture; and injection means (18) for injecting the predetermined gaseous mixture into the enclosure (10) and comprising an externally frustoconical nozzle provided with an injection orifice situated at one end and shaped as a function of the injection orifice and of the column configuration of the plasma formed, said nozzle having means for heating