Stéréolithographie des matériaux céramiques (cinétique de photopolymérisation et interactions rayonnement-matière)

LIMOGES-BU Sciences (870852109) / SudocSudocFranceF

Optical characterization of stereolithography alumina suspensions using the Kubelka-Munk model

International audienceThe multiple light scattering in concentrated alumina suspensions adapted to stereolithography can be modeled using diffuse reflectance measurements coupled to the Kubelka-Munk model. The penetration depth of UV radiation can be related to the scattering coefficient allowing the prediction of the cure depth with an accuracy of 20%

Stereolithography process: Influence of the rheology of silica suspensions and of the medium on polymerization kinetics - Cured depth and width

International audienceUV laser stereolithography is a rather new shaping technique that makes it possible the fabrication of complex 3D ceramic structures with a high dimensional accuracy. The green part is built through layer by layer photopolymerization of a light sensitive suspension. Polymerization is thus a critical step to control in this shaping technique. Photopolymerization, with the initiation, propagation and termination reactions, involves the mobility of reactive species and is then sensible to the rheology of the media. This study investigated the influence of the rheology of suspensions of silica particles in an acrylate oligomer and of the intergranular curable organic phase on the UV polymerization. In this respect, the effects of the powder concentration, the state of dispersion and of the dilution of the reactive oligomer on polymerization, are measured. In addition, the influence of the powder loading on the cure depth and cure width, which are respectively pertinent indicators of the reactivity of the suspension and of the dimensional accuracy of the green part, is evaluated

Net-shape forming of complex ceramic parts with a high dimensional resolution : stereo- and microstereo-lithography

International audienc

Study of the Effect of Calcium Substitution by Magnesium in the Vitreous System 3P2O5-2K2O-(1 − x) CaO-x MgO

Phosphate glasses have potentially interesting properties that can be used in various applications. Recently, different studies are focusing on their dissolution behaviours that can be modified to suit some environmental applications, such as controlled-release fertilisers. In this work, magnesium had been suggested to improve the glass durability of 3P2O5-2K2O-(1 − x)CaO-xMgO glasses (0 ≤ x ≤ 1). Indeed, its effect on glass structure, thermal properties and most important dissolution behaviours were studied, in order to evaluate their suitability of being used as controlled-release fertilisers. Various compositions in which calcium was partially replaced by magnesium were prepared by melting at 800 °C. The samples were characterised by differential scanning calorimetry, density measurements, X-Ray diffraction, FTIR spectroscopy and Raman spectroscopy. The dissolution behaviours were investigated using inductively coupled plasma optical emission spectrometry ICP-OES, pH measurements and SEM. Substitution of calcium by magnesium reduced the glass density, owing to the lower atomic weight of magnesium compared to calcium, and caused an increase in glass transition and crystallisation temperatures. Magnesium substitution significantly improved the chemical durability of the glasses due to more covalent Mg–O bond than the Ca–O bond. This study demonstrated that 3P2O5-2K2O-0.3CaO-0.7MgO (x = 0.7) had a dissolution profile adequate to the criteria of controlled-release fertilisers and could be used to nourish the plants with phosphorus, potassium, calcium and magnesium

3D ceramic microstereolithography applied to sub-millimeter devices manufacturing

International audienc

Study of borosilicate glaze opacification by phosphates using Kubelka-Munk model

International audienceThe aim of this work was to study the effects of additions of sodium metaphospahte (1–50 Wt.%) on optical properties of a conventional borosilicate glaze.The optical properties were evaluated by diffuse reflectance measurements. The absorption and the scattering properties of the obtained glazes, were explained through the Kubelka-Munk model. The structural and microstructural properties were determined by X-ray diffraction and Scanning Electron Microscopy. It was shown that white opaque borosilicate glazes can be obtained for an addition of 5 Wt% to 50 Wt% of sodium metaphosphate and 20 Wt% seemed the optimum amount to obtain a perfect white opacity. The opacification process is based on the light scattering phenomenon wherein the nature of the scattering centers vary depending on the amount of sodium metaphosphate addition. In the case of 20 Wt% scattering centers have been identified as Ca10(PO4)6O and NaCa(PO4) crystals formed by a devitrification process

Micro stéréolithographie céramique 3D appliquée à la fabrication de composants sub-millimétriques

Session Orale : 8A