ADVANCED MATERIALS & PROCESSES | JULY/AUGUST 2024 56 iTSSe TSS iTSSe TSS 12 Fig. 2 — Image of a splat resulting from the flattening of a particle (40 µm) impacting onto a substrate at room temperature. UNDERSTANDING OF SPRAY COATING ADHESION THROUGH THE FORMATION OF A SINGLE LAMELLA Simon Goutier, Michel Vardelle, and Pierre Fauchais Published in Vol 21(3–4), March 2012, this paper details an experimental setup designed to study the formation of a single lamella in the thermal spray process and is composed of a fast (50 ns) two-color pyrometer and an imaging system, comprising two fast (1-10 µs) CCD cameras triggered by the velocity signal of the particle in flight prior to its impact. This experiment is focused on alumina particles flattening onto stainless steel (304L) substrates preheated at different temperatures during different times. (Fig. 2) LATEST DEVELOPMENTS IN SUSPENSION AND LIQUID PRECURSOR THERMAL SPRAYING Pierre Fauchais and Ghislain Montavon Published in Vol 19(1–2), January 2010, this review presented recent developments and present knowledge in the thermal spray field at the time of publication, specifically suspension thermal spraying (STS) and solution precursor thermal spraying (SPTS), both allowing the ability to manufacture finely structured layers of thicknesses varying between a few micrometers up to a few hundreds of micrometers. It argued that compared to conventional thermal spray routes, STS and SPTS are by far more complex because fragmentation and vaporization of the liquid control the coating build-up mechanisms. (Fig. 3) Fig. 3 — Coating surface morphology from low-concentration solution precursor. PARTICLE TEMPERATURE FLUCTUATIONS IN PLASMA SPRAYING Simon Goutier, Elise Noguès-Delbos, Michel Vardelle, and Pierre Fauchais Published in Vol 17(5–6), December 2008, this study employs two online techniques that 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. 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. (Fig. 4) Fig. 4 — Experimental setup for measuring the particle temperature and voltage fluctuations. PARAMETERS CONTROLLING LIQUID PLASMA SPRAYING: SOLUTIONS, SOLS, OR SUSPENSIONS Pierre Fauchais, Ramuntxo Etchart-Salas, Vincent Rat, Jean-François Coudert, Nadège Caron, and Karine Wittmann-Ténèze Published in Vol 17(1), March 2008, this article presented, at the time of publication, the thermal spray community’s current knowledge of the plasma spraying of suspension, sol, and solution in order to achieve finely or nano-structured coatings. The paper presents examples of applications such as solid oxide fuel cells, thermal barrier coatings, photocatalytic titania, hydroxyapatite, WC-Co, complex oxides or metastable phases, and functional materials coatings. (Fig. 5) Fig. 5 — Interaction of an Ar-H2 (45-15 slm) dc plasma jet (I = 600 A, anode-nozzle i.d. 7 mm) with an atomized ethanol jet. JTST HIGHLIGHTS
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