Copper tracks processing on alumina by laser cladding: Elaboration and characterization

International audienceA laser process allows achieving in air electrical tracks on alumina substrates with an electrical conductivity of 5.106 Sm−1. Copper paste was first put on alumina substrates and it was heated following a narrow track (c.a. 400 m wide). Copper melted and oxidized partially during treatment forming cuprite Cu2O. A reaction occurs between Cu2O and alumina substrates which provides, after cooling, a good bonding of the copper-based tracks onto the substrates. Conditions of laser exposure have to be sharply controlled: if insufficient, tracks do not adhere to the substrate, and if too long, alumina substrates are hollowed, cracked, with vaporizations of copper and ejections of alumina. However the feasibility of such a process is now establishe

Comparative study of an argon plasma and an argon copper plasma produced by an ICP torch at atmospheric pressure based on spectroscopic methods

International audienceThe aim of the paper is to test the accuracy of classical spectroscopic methods in the visible domain dedicated to measurements of temperature and electron density in order to conclude about the validity of thermal disequilibrium. The influence of various factors is studied: accuracy of the intensity calibration, Abel inversion of the experimental spectra, excitation temperature deduced from the relative method, absolute excitation temperature, influence of the transition probability, accuracy, influence of the Biberman factor value, electron temperature from the line-to-continuum intensity ratio, electron density deduced from Stark broadening, and electron density deduced from the continuum intensity. This spectroscopic investigation is carried out for argon plasma and argon copper plasma both produced by means of an ICP torch operating at atmospheric pressure. Results are given with uncertainties for each evaluated parameter. We show that, first, the electron temperature deduced from the line-to-continuum intensity ratio has to be considered with great care; second, for argon plasma no evidence of thermal disequilibrium can be discerned, whereas for argon copper plasma a small disequilibrium of 1.2 to 1.4 at most is experimentally observed

Kinetics of some iron-based alloys in industrial CO2 : formation of wüstite phase

International audienceThis work compares the oxidation behaviour of three iron-based substrates (C40E, Invar® and 304L) in CO2 industrial gas, in order to determine the conditions for producing wüstite (Fe1-xO), on the basis of kinetic and morphologic studies. For the three alloys at the beginning of the reaction, wüstite formed under 105 Pa of CO2 following a rate law ≥ ≥ ∃ RT 220000 10.2 P e dt d( m/S) CO2 . For 304L, formation of a spinel phase chromite briefly preceded it during a first step. Magnetite appeared for long times of experiment, in the case of Invar® and 304L. This can be explained by the stopping of iron outer diffusion. These results are discussed according to the literature and thermodynamic data. They open new fields for coating these alloys by plasma spray processes

Faisabilité d'une méthode d'évaluation de la résistance thermique de contact entre une lamelle céramique écrasée sur un substrat métallique

International audienceThis paper presents an experimental procedure to evaluate the Thermal Contact Resistance (RTC) between a ceramic deposit (of 1 m in thickness), obtained by plasma spraying, and metallic polish substrate. The procedure consists on submitting the lamella to a heat flux and calculates the thermal field in the deposit/substrate configuration taking into account the RTC parameter. Heat flux is provided by a laser beam and the lamella irradiation duration is estimated from the laser scanning velocity. Values of 10-4 m2.K/W of the RTC have been measured, that extend the identification range with the present method to strong values of this paramete

Relevant parameters for laser bonding of copper on alumina

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Identification of parameters involved in the bonding of copper tracks on alumina substrates by a laser process

International audienceA laser process was used to produce copper tracks on alumina substrates. Many parameters involved made it tricky. In order to determinate the most influent factors among laser beam diameter, laser power, scanning velocity, preheating temperature of the substrate, scanning overlap and copper grains size, a Plackett and Burman's design of experiments has been used. With a very limited number of experiments, this method allowed to obtain first encouraging result

Temperatures of Titan and Mars-like plasmas measured by laser interferometry

International audienceThis paper presents measurements of temperature profiles of Mars and Titan-like plasmas created with an Inductively Coupled Plasma torch, using a Mach-Zehnder interferometer. Acquired interferograms were treated using Fast Fourier Transform and Abel inversion to obtain the radial distribution of the plasma index refraction. Temperature profiles were then obtained from Gladstone-Dale relation, taking in account the plasma composition versus temperature

Evaluation du transfert thermique instationnaire lors de traçage de pistes en cuivre sur un substrat en alumine par traitement laser

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