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Alliages métalliques pour l'étalon de masse de la balance du watt et des références secondaires

Abstract : The unit of mass, the kilogram, is the last base unit of the International System of Units (SI) defined by a material artefact. This definition is limited by the stability of the material that forms the international prototype. In fact, deviations that can reach 2 μg.year-1 are observed at the level of the official copies of the international prototype made of platinum iridium. In order to improve the stability of the unit of mass, several experiences began to link the kilogram to a fundamental constant. One of those programs, actually the most promising, is named "watt balance" and aims at linking mechanical measurements to electrical measurements. In this experience, a reference mass standard is necessary, but the use of the platinum iridium alloy is not conceivable. Researches are actually turned towards gold platinum alloys or other precious metals. Moreover, the dissemination of the unit of mass, from 1 g to 10 kg, is generally carried out with stainless steel mass standards. As the stability of the international prototype is not ensured, this phenomenon is strongly accentuated at the level of these secondary standards. To take advantage of the expected improvement of the conservation of the unit of mass, it is necessary to increase the stability of the secondary mass standards. The characterization of new metallic alloys and the study of their stability become then necessary.
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Submitted on : Monday, July 2, 2007 - 6:33:39 PM
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  • HAL Id : tel-00159327, version 1


Paul-André Meury. Alliages métalliques pour l'étalon de masse de la balance du watt et des références secondaires. Mécanique []. École Nationale Supérieure des Mines de Paris, 2005. Français. ⟨NNT : 2005ENMP1320⟩. ⟨tel-00159327⟩



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