Elaboration et caractérisation d'alliages réfractaires pour la fusion du verre : alliages Mo WCr, alliage base Ni "bi-ODS"

Abstract : Elaboration of glass (fusion and working) is clone at very high temperatures. The refractory materials used in the corresponding industrial processes must satisfy three essential criteria (good resistance to corrosion by glass melts and to HT. oxidation by air, good mechanical properties). Since some process temperature can exceed 1300ÊC, Ni or Co base alloys cannot be used in such cases. We have thus focused our study on chromia forming Mo and W base alloys (these two metals being known for their resistance to molten glass and their good mechanical properties at high temperature, chromia being very resistant to molten glass). The melting temperatures of the components are very different. Elaboration by melting techniques cannot be used; all syntheses have thug been clone by sintering of metallic powders, with palladium as an activating agent. The study of the mechanical properties and of the resistance to oxidation resistance of these alloys bas concerned a wide range of compositions. It was shown that the mechanical properties and the oxidation behaviour are closely related to the characteristics of diffusion in the alloys. Part of this work was thus devoted to the determination of the Cr-Mo-W temary phase diagram and to the diffusion coefficients of the elements. The study of the MoW base alloys oxidation properties bas evidenced the beneficial effect of a chromia dispersion in the alloy. By extension, this result led us to study new ODS Ni base alloy (MA758 type) with an original alloy concept ( "Bi-ODS" alloy containing two oxide dispersions), the behaviour of which is significantly improved as regards H.T. oxidation and corrosion by molten glass.
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Sébastien Diliberto. Elaboration et caractérisation d'alliages réfractaires pour la fusion du verre : alliages Mo WCr, alliage base Ni "bi-ODS". Autre [cond-mat.other]. Université Henri Poincaré - Nancy 1, 2000. Français. ⟨NNT : 2000NAN10089⟩. ⟨tel-01748007⟩

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