Objetivo
The chief o bjective is to develop silver-free electrical contacts for low voltage circuit breakers. In order to find new materials, the first step is to acquire a better knowledge of the mechanisms giving rise to contact material deterioration (oxidation, sticking, abrasion from arcing) to identify the physicochemical properties of the contact material involved in the phenomena, and finally to evaluate the contribution of the microstructure of the contact material to their properties and performance in operation. The second step is to define, from the previous results, the guidelines for new materials. The first part of the study is carried out on Cu-Ni/Graphite composites used as model materials.
The research covered the development of silver free electrical contacts for low voltage circuit breakers and minimisation of production costs of electrical contacts by increasing the effectiveness of composites which could replace silver in low voltage circuit breakers.
There are, in theory, 6 alternative ways of obtaining a satisfactory composite by combining 2 alternative ways of presenting graphite (particles or fibres) and 3 alternative consolidation methods (pressureless sintering, hot unaxial pressing and a third, alternative method developed by the researchers). In practice, only 3 out of the 6 combinations were practicable. The first step in carrying out the project used copper-nickel/graphite composites after preliminary microstructural studies indicated their promising possibilities to replace silver in electrical contacts for low voltage circuit breakers. Although partners expected to extend the results to composites of similar characteristics, information obtained was hardly extendable to other composites. As a consequence, the second step of the research focussed on the study of only copper-nickel/graphite composites; good performances were obtained for low voltage breakers used in consumer terminal distributions. For such devices, the breaking and life demands are not too heavy. For higher voltage industrial breakers, however, further work is necessary and, moreover, their electrical performance is not yet satisfactory.
Copper-nickel/graphite composites are potential substitutes for silver based materials used in low voltage circuit breakers. The microstructure versus properties relationships in composties containing a dispersion of graphite particles were thoroughly investigated. New composites have also been prepared using graphite fibres. The electrical conductivity is found to be significantly affect by the graphite volume fraction and by the anisotropy factors of the microstructure while the electrical contact characteristics mainly depend on the graphite fraction adn are stable and sufficient in the graphite range 8 to 12%. The mechanical properties are decreased by the graphite content and the poor interface adhesion between the copper-nickel matrix and graphite.
In order to promote interface adhesion composties were prepared using carbide forming elements (tungsten, silicon, chromium). The chromium content and processing conditions should be tuned in order to promote adhesion without inducing the extensive formation of a brittle phase along the interfaces.
Copper nickel graphite composites when associated with silver carbide yields excellent result for contact resistance and wear.
THE RESEARCH PROGRAMME CONCERNS :
- THE STUDY OF THE MECHANISMS GIVING RISE TO CONTACT MATERIAL DETERIORATION (OXIDATION, STICKING, ABRASION FROM ARCING OR MOTION).
- THE IDENTIFICATION OF THE PHYSICO-CHEMICAL PROPERTIES INVOLVED IN THE PHENOMENA.
- THE DETERMINATION OF THE RELATIONSHIP BETWEEN MICROSTRUCTURE, PROPERTIES AND MATERIAL PERFORMANCE IN OPERATION.
THE NOVEL ASPECTS OF THE PROGRAMME MAINLY RELATE TO :
- THE STUDY OF THE INFLUENCE OF THE MICROSTRUCTURE AND THE INTERFACE CHARACTERISTICS OF THE MATERIALS ON THE PERFORMANCE IN-SERVICE.
- THE CLOSE COLLABORATION OF THREE SPECIALIZED GROUPS OF SCIENTISTS INCLUDING METALLURGISTS, PHYSICO-CHEMISTS AND ELECTRICAL ENGINEERS.
CONTACT MATERIALS GENERALLY CONSIST OF AG- BASED COMPOSITES, TYPICALLY WITH AG/NI, OR AG/C WITH AG PLATED CU. SUCH MATERIALS COMBINE THE PROPERTIES OF HIGH ELECTRICAL CONDUCTIVITY OF THE SILVER MATRIX WITH THE ERROSION AND ARCING RESISTANCE OF HIGH MELTING OR REFRACTORY ELEMENTS (NI, C, W, ...) OR COMPOUNDS (CARBIDES, OXIDES). THE SUBSTITUTION OF SILVER, BY CHEAPER ELEMENTS WOULD RESULT IN SIGNIFICANT FINANCIAL BENEFITS. FURTHERMORE, THE LIMITED WORLDWIDE RESSOURCES OF AG MUST FURTHER RESTRICT THE FUTURE USE OF CONTACT MATERIALS CONTAINING AG. THESE TWO ECONOMIC AND STRATEGIC ASPECTS CONSTITUTE A STRONG INCENTIVE TO PROMOTE THE RESEARCH FOR NEW AG-FREE MATERIALS FOR MERLIN-GERIN, 3RD EUROPEAN PRODUCER OF LOW VOLTAGE CIRCUIT BREAKERS IN THE WORLD. FROM A PRELIMINARY STUDY CARRIED OUT BY MERLIN-GERIN AND LTPCM, A CU-BASED COMPOSITE SEEMS TO HAVE SATISFACTORY CONTACT RESISTANCE AND NON-WELDING PROPERTIES. CONSEQUENTLY, THE COMPLETE STUDY OF THIS MATERIAL, WHICH CONTAINS GRAPHITE PARTICLES (5%) DISPERSED IN A CU-NI (5-10%) MATRIX, IS OF INTEREST IN VIEW OF FURTHER INDUSTRIAL DEVELOPMENT.
Ámbito científico (EuroSciVoc)
CORDIS clasifica los proyectos con EuroSciVoc, una taxonomía plurilingüe de ámbitos científicos, mediante un proceso semiautomático basado en técnicas de procesamiento del lenguaje natural. Véas: El vocabulario científico europeo..
CORDIS clasifica los proyectos con EuroSciVoc, una taxonomía plurilingüe de ámbitos científicos, mediante un proceso semiautomático basado en técnicas de procesamiento del lenguaje natural. Véas: El vocabulario científico europeo..
- ciencias naturales ciencias físicas electromagnetismo y electrónica
- ingeniería y tecnología ingeniería de materiales compuestos
- ciencias naturales ciencias químicas química inorgánica compuestos inorgánicos
- ciencias naturales ciencias químicas electroquímica electrólisis
- ciencias naturales ciencias químicas química inorgánica metales de transición
Para utilizar esta función, debe iniciar sesión o registrarse
Programa(s)
Programas de financiación plurianuales que definen las prioridades de la UE en materia de investigación e innovación.
Programas de financiación plurianuales que definen las prioridades de la UE en materia de investigación e innovación.
Tema(s)
Las convocatorias de propuestas se dividen en temas. Un tema define una materia o área específica para la que los solicitantes pueden presentar propuestas. La descripción de un tema comprende su alcance específico y la repercusión prevista del proyecto financiado.
Datos no disponibles
Las convocatorias de propuestas se dividen en temas. Un tema define una materia o área específica para la que los solicitantes pueden presentar propuestas. La descripción de un tema comprende su alcance específico y la repercusión prevista del proyecto financiado.
Convocatoria de propuestas
Procedimiento para invitar a los solicitantes a presentar propuestas de proyectos con el objetivo de obtener financiación de la UE.
Datos no disponibles
Procedimiento para invitar a los solicitantes a presentar propuestas de proyectos con el objetivo de obtener financiación de la UE.
Régimen de financiación
Régimen de financiación (o «Tipo de acción») dentro de un programa con características comunes. Especifica: el alcance de lo que se financia; el porcentaje de reembolso; los criterios específicos de evaluación para optar a la financiación; y el uso de formas simplificadas de costes como los importes a tanto alzado.
Régimen de financiación (o «Tipo de acción») dentro de un programa con características comunes. Especifica: el alcance de lo que se financia; el porcentaje de reembolso; los criterios específicos de evaluación para optar a la financiación; y el uso de formas simplificadas de costes como los importes a tanto alzado.
Coordinador
38402 SAINT-MARTIN-D'HERES
Francia
Los costes totales en que ha incurrido esta organización para participar en el proyecto, incluidos los costes directos e indirectos. Este importe es un subconjunto del presupuesto total del proyecto.