Metalor Technologies France SAS

Courville-sur-Eure, France

Metalor Technologies France SAS

Courville-sur-Eure, France

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Leung C.,Metalor Technologies Americas | Harman D.,Metalor Technologies Americas | Doublet L.,Metalor Technologies France SAS | Bourda C.,Metalor Technologies France SAS | And 2 more authors.
IET Conference Publications | Year: 2012

Several Ag/C and Ag/WC/C contact materials used as stationary contacts in MCCB (molded case circuit breakers) are compared for electrical and mechanical properties. The mechanical lives of the MCCB can be limited by the stationary contact chipping due to the impact by the much harder moving contacts of Ag/W and Ag/WC. Transverse Rupture Strengths are therefore measured by a 3 point bending test, and impact lives on a model switch designed to evaluate material cracking and chipping. The test results are discussed to illustrate the optimization of metallurgical and electrical properties.


Vassa A.,Metalor Technologies France SAS | Vassa A.,CNRS Neel Institute | Vassa A.,French National Center for Scientific Research | Carvou E.,French National Center for Scientific Research | And 5 more authors.
IET Conference Publications | Year: 2012

The behavior of the arc formed during electrical circuit opening is examined, in the presence of a pulsed magnetic field. The field is applied in the inter-electrode gap where the arc develops. The opening sequence may be separated into two temporal phases. During the first phase, the arc remains stuck at the same position as under zero field. This is ascribed to the existence of a sticking force, which overcomes the Laplace force. The sticking force is related to the high pressure existing in the plasma. During the second phase, the Laplace force dominates. The arc is blown out of the contact region in a time duration of 1 to 1.5 ms. A model is developed which provides a semiquantitative account of the experimental behavior.


Vassa A.,Metalor Technologies France SAS | Vassa A.,CNRS Neel Institute | Vassa A.,French National Center for Scientific Research | Carvou E.,French National Center for Scientific Research | And 7 more authors.
Electrical Contacts, Proceedings of the Annual Holm Conference on Electrical Contacts | Year: 2010

The phenomenon of magnetic blowing allows drastic reduction in arc duration. It is of specific interest in DC applications, more specifically in automotive applications. Blowing exploits the action of the magnetic force on the transitory arc formed during circuit opening. A new contact was described in a previous paper in which the magnetic field required for blowing is generated by the contact material itself. In the present study, aimed at a more thorough analysis of magnetic blowing, an external adjustable magnetic field (up to 320 mT) was produced by placing magnets on each side of the contact. The experiments were performed for voltage values from 42 VDC to 360 VDC and currents up to 100 A, using a resistive circuit. For considered magnetic field values, no magnetic blowing was observed below a certain critical current. At high current, the arc duration was found to be approximately current independent, following a phenomenological 1/√B variation. Under 42 V DC and the maximum current of 100 A, the arc duration under 320 mT was reduced by a factor of 100 as compared to the arc duration under zero field. Qualitative account of the present phenomena is obtained by considering that blowing is governed by the competition between the magnetic force acting on the arc and the force acting against arc motion, originating from the enthalpy expense needed to move the arc from a heated region at the contact surface to a colder one. ©2010 IEEE.


Choi E.Y.K.,Metalor Technologies France SAS | Choi E.Y.K.,French National Center for Scientific Research | Carvou E.,French National Center for Scientific Research | Bourda C.,Metalor Technologies France SAS | And 3 more authors.
Electrical Contacts, Proceedings of the Annual Holm Conference on Electrical Contacts | Year: 2015

Contact resistance is usually determined by the ratio of the voltage to the current and the increase of this value means that the contact interface is degraded. However for high currents, this ratio is not constant so Ohm's law does not apply. In this paper, we study the electrical behaviour through degraded surface materials (Ag and Ag with various metal oxides) aged by break arcing up to 90A at 42VDC with a contact force of 14N. In order to make a current voltage characteristic, the samples are tested with increasing current (I) from 50mA to 75A and then decreasing from 75A to 50mA. The main result is that the proportionality between the current and the voltage is ensured up to 70mV. Beyond this value this proportionality is lost and voltage break down takes place at different level of fritting voltage. However this phenomenon is frequently observed during the first applied current ramp (increasing), and disappears at the decreasing current ramp and during further tests. Discussions here are given concerning the constant fritting voltage over a wide current range being related to the breakdown of thin oxide films on the degraded surface and/or the creation of additional contact spots. © 2014 IEEE.


Carvou E.,Rennes Institute of Physics | Le Garrec J.L.,Rennes Institute of Physics | Choi E.Y.K.,Rennes Institute of Physics | Choi E.Y.K.,Metalor Technologies France SAS | Mitchell J.B.A.,Rennes Institute of Physics
Proceedings of the 59th IEEE Holm Conference on Electrical Contacts, HOLM 2013 | Year: 2013

This article discusses recent synchrotron radiation based measurements of nanoparticle formation between arcing contacts. © 2013 IEEE.


Zeralli Y.,MINES ParisTech Center of materials | Zeralli Y.,Metalor Technologies France SAS | Proudhon H.,MINES ParisTech Center of materials | N'Guyen F.,MINES ParisTech Center of materials | And 3 more authors.
Proceedings of the International Thermal Spray Conference | Year: 2012

Cold spray can substitute for several coating processes for various applications, due to a high efficiency coupled with high properties for the sprayed product. The use of a composite powder rather than a powder blend was shown to be beneficial, especially for the cold spray of electrical contacts. The objective of this work is to optimize a composite powder (Ag-14wt% SnO 2) using numerical simulation of the deformation of the particle at the impact onto the substrate (Cu). Every elementary composite particle was made of an agglomerate of Ag and SnO2 smaller particles, which exhibited more or less porosity depending on the powder processing conditions. The first step was to study the distribution of these various constituting phases plus porosity. Three types of powders which showed different phases and porosity characteristics deliberately were developed. Three-dimensional images of the agglomerate were acquired using microtomography which exhibited the porosity network well in the dual-phased particle material. These actual 3D images were used to feed a simulation of the impingement of a particulate agglomerate to result in a splat onto the substrate. For this, a two dimensional deformation model was developed on the route to a three-dimensional model which is expected to be more powerful. The influence of agglomerate characteristics, primarily porosity, on the deformation behavior was studied. Consequences on splat-substrate adhesion and deposition efficiency could therefore be investigated in the light of direct observation of the cold-sprayed material. Copyright 2012 ASM International®. All rights reserved.


Rolland G.,MINES ParisTech Center of materials | Zeralli Y.,MINES ParisTech Center of materials | Zeralli Y.,Metalor Technologies France SAS | Guipont V.,MINES ParisTech Center of materials | And 4 more authors.
IET Conference Publications | Year: 2012

This work shows the feasibility of cold spray for the achievement of industrial electrical contacts to be used in contactors and circuit breakers. Cold spray was demonstrated to be a very promising process to substitute for usual powder metallurgy (P/M) routes. Prototype parts were processed by cold spray then tested in industrial testing facilities using industrial conditions. Material loss due to erosion was determined periodically during series of interrupted tests. The results were compared to those obtained for conventional commercial P/M contacts. Damage mechanisms of cold-sprayed contacts were studied using both optical and scanning electron microscopy. From the related damage study, cold-sprayed contacts were shown to compare more than well with those processed with the conventional P/M method despite adhesion, which has to be improved. This does open an innovative and cost-attractive production route for electrical contacts.


Leung C.H.,Metalor Technologies Americas Corporation | Harman D.,Metalor Technologies Americas Corporation | Doublet L.,Metalor Technologies France SAS | Bourda C.,Metalor Technologies France SAS
Electrical Contacts, Proceedings of the Annual Holm Conference on Electrical Contacts | Year: 2010

Arc mobility on contact surface is an important factor in contact erosion and circuit interruption. The two stages of arc mobility are the initial immobile arc followed by the running arc. Past work in the literature showed that immobile arc time is dependent of contact material, current and contact separation speed until a minimum separation speed is reached. When the arc is in the running stage, then contact material strongly affects arc velocity. In this paper, we re-examine the contact material effect with analysis of the arc spot eroded surface morphology to compare material modifications that can affect the arc mobility and reignition. A static gap discharge with various external magnetic field strength is used to affect the arc mobility. Several groups of contact materials are examined including Ag or Cu, Ag, and in composites with C, W, WC, CdO, SnO2. ©2010 IEEE.

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