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

Tailoring the Spray Conditions for Suspension Plasma Spraying

International audienc

In-flight mechanisms in Suspension Plasma Spraying Issues and perspectives

International audienceSuspension Plasma Spraying (SPS) has aroused much research efforts over the two last decades to describe and understand the in-flight mechanisms of suspension plasma processing by developing advanced diagnostics and models. This research field has highlighted the intricate and prevailing dependence of the coating properties, and especially the rich variety of attainable microstructures, on the thermal and dynamic histories of the submicron particles in the plasma jet. This paper gives an overview of the major key points to control from the plasma torch operation up to the coating build-up. The main diagnostics methods are examined and the most advanced models as well. The perspectives focus on the key issues to improve the basic understanding of the in-flight phenomena. They also insist on a necessary multiscale approach to combine the diagnostics and the models in order to form relevant data flows for machine learning algorithms and better process prediction and reliability

Twelve year observation of primary and secondary antibiotic-resistant Helicobacter pylori strains in children.

The effectiveness of Helicobacter pylori eradication regimens is influenced by antibiotic susceptibility of infecting strains. Data concerning antibiotic resistance in children are limited. We report the evolution of primary and secondary resistance in a series of Belgian children during the last 12 years.Journal ArticleSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Particle temperature fluctuations in plasma spraying

International audienceIn direct current (d.c.) plasma spray torches, the dynamic behavior of the arc attachment at the anode nozzle results in arc voltage fluctuations and correspondingly power fluctuations. The resulting plasma jet instabilities affect the treatment (heat and momentum) of particles injected in the plasma flow and, thus, the coating quality. However, it is not clear if the experimentally observed fluctuations of particle temperatures are a major phenomena and if their frequencies are always in unison with those of voltage. In this study, two online techniques are used to investigate, respectively, the time variation of particle temperatures and its correlation with voltage variations; the first technique makes it possible to analyze plasma voltage instabilities and the second one to investigate those of particle temperatures. Both allow determining the frequencies and amplitude variations of voltage and particle temperature. Experiments were carried out with three plasma torches (F4-type and two 3MB-type) using, respectively, argon-hydrogen (F4-type and 3MB) and nitrogen-hydrogen (3MB) mixtures (all with restrike mode for the voltage fluctuations) as plasma-forming gases. A good correlation between arc voltage and particle temperature fluctuations is observed when the plasma torch is operated with argon-hydrogen mixtures and high mass flow rate. However, it is not the case when the torch is operated with nitrogen-hydrogen mixtures even if the amplitudes of voltage fluctuations are two to three times higher than those obtained with Ar-H2