Analyse μ-structurale du fil électrode en soudage MIG-MAG : Cas des mélanges Ar-CO2 et Ar-O2

L’étude réalisée porte sur l’influence de la nature et de la proportion de gaz actif dans le gaz de protection sur le comportement du soudage MIG-MAG en polarité inverse. Une analyse de la colonne d’arc par spectroscopie optique d’émission et imagerie rapide équipée d’un filtre interférentiel, complétée par une étude physico-chimique de l’extrémité du fil électrode par sonde de Castaing, MEB-EDX et DRX. Cela permet de formuler des hypothèses quant aux mécanismes mis en jeu concernant les phénomènes observés en régime spray sous Ar, Ar-CO2 et Ar-O2

Tunable SiO2 to SiOxCyH films by ozone assisted chemical vapor deposition from tetraethylorthosilicate and hexamethyldisilazane mixtures

Silica and silica-based materials with tunable functionalities are frequently encountered in low-k material applications, porous membranes, and microelectonic devices. In the present study, an innovative O2/O3 assisted CVD process for the deposition of such films at moderate temperature is presented, based on a dual precursor chemistry from hexamethyldisilazane (HMDS) and tetraethyl orthosilicate (TEOS). Films with tunable carbon content were obtained through variation of the HMDS flow ratio. A comprehensive FT-IR study reveals the transition of the material from a SiOxCyH type film containing -CH3 moieties, to a methyl-free SiOx film with the increase of the temperature. At the same time the water contact angle of 81.0° at 400°C is decreased to 52.8° at 550°C, related to the absence of methyl moieties in the latter. Ion beam analysis (IBA) confirms the lack of carbon in the films when deposition temperatures are equal to or exceed 500°C. The resistance to liquid corrosion is investigated as a function of the deposition temperature; SiOx type films present a low Pliskin etching rate of 15 Å.s-1, with this value increasing to 60 Å.s-1 for the SiOxCy:CH3 films produced at the lower temperatures. It is found that the addition of HMDS to a TEOS chemistry can be utilized to modulate the film composition from SiOx to SiOxCyH and by such, tune the film functional properties, in particular its etching rate, opening the way to the development of new sacrificial films

Network hydration, ordering and composition interplay of chemical vapor deposited amorphous silica films from tetraethyl orthosilicate

The chemical or mechanical performance of amorphous SiO2 films depend on intrinsic physicochemical properties, which are intimately linked to atomic and molecular arrangements in the Si–O–Si network. In this context, the present work focuses on a comprehensive description of SiO2 films deposited from a well-established chemical vapor deposition process involving tetraethyl-orthosilicate, oxygen and ozone, and operating at atmospheric pressure in the range 400–550 °C. The connectivity of the silica network is improved with increasing the deposition temperature (Td) and this is attributed to the decreased content of hydrated species through dehydration-condensation mechanisms. In the same way, the critical load of delamination increases with increasing Td thanks to the silicon substrate oxidation. The utilization of a O2/O3 oxidizing atmosphere involving the oxidation of intermediates species by O2, O3 and O., allows increasing the deposition rate at moderate temperatures, while minimizing carbon, H2O and silanol contents to extremely low values (4.5 at.% of H). The SiOx stoichiometry and Td interplay reveals two distinct behaviors before and above 450 °C. The best corrosion resistance of these films to standard P-etching test is obtained for the minimum silanol content and the best network molecular ordering, with an etching rate of 4.0 ± 0.1 Å/s at pH = 1.5. The elastic modulus and hardness of the films remain stable in the investigated range of deposition temperature, at 64.2 ± 1.7 and 7.4 ± 0.3 GPa respectively, thanks to the low content in silanol groups

Fil fourré 'metal cored' pour soudage sous mélange Ar/CO2 riche en CO2

[Colloque 14 : " Le soudage au service des énergies du futur " + 8e Journées Nationales du Soudage] Communication orale (N.Pellerin)National audienc

Comparison between direct and reverse polarity in GMAW

[P2.11.27 - Topic 11 : Plasma spray and thermal plasma material processing] /International audienc

Production d’eau activée par plasma via une décharge d’arc glissant à pression atmosphérique : Analyse des phénomènes d’activation en milieux aqueux

International audienc

Experimental study of Plasma Activated Water using Gliding Arc Discharge at atmospheric pressure: Process optimization and analysis of the chemical activation phenomena in aqueous media

[Communication orale]International audienc

Treatment by gliding arc of epoxy resin: Preliminary analysis of surface changes

[Poster]International audienc

Etude de l'enrichissement en carbone de l'anode en soudage MIG-MAG

Communication orale (F.Valensi)National audienc