Functionalizing surfaces of 3D printed objects with an integrated low-cost atmospheric pressure micro plasma torch

Polymer 3D printing via the Fused Filament Fabrication (FFF) technology is a now well-known process designed to build three-dimensional objects from computer-aided-design (CAD) models in a layer-by-layer method. First dedicated for prototyping, this technology is now widely spread on the additive manufacturing (AM) and production market. With the decreasing costs of the equipment and materials needed as well as the growing simplicity of use and reliability of the technique, one can now have a 3D printer for the same cost and as user-friendly as a regular desktop inkjet printer. Among the commercially distributed thermoplastics, polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) are the two most outspread but one can also find acrylonitrile styrene acrylate (ASA), polyethylene terephthalate (PET) polycarbonate (PA) and much more. When assuming that single material 3D printed objects are obtained from growing layers in the (xy) plane stacked along the z axis, they are known to show really good tensile strength in the x and y direction but much less in the z direction due to insufficient interlayer bounding. Bigger problems arise when trying to print a multi-material object. Indeed, the chemical incompatibility of the different printed materials as well as their different thermal expansion coefficients are from the materials properties that can cause a very weak diffusion bonding at the interface. Authors started recently to focus on this problematic and very few studies can be found on the subject. To overcome the problem, we consider here improving the wettability of the printed polymer at the interface layer as it cause the extruded material to better spread over this layer, hence increasing the diffusion bonding. This work aims to investigate the effect of an atmospheric cold plasma treatment on the wettability and bonding of 3D printed objects. For this task, we designed an atmospheric pressure dielectric barrier discharge (DBD) plasma torch integrated on a commercial 3D printer. Thus, the device can be controlled to apply a plasma treatment while printing an object. As the deposition process will need to be done on complex surfaces and on thermal sensitive materials, a new type of high voltage nano-pulse generator had to be developed for this device. It gives the possibility to generate a homogeneous plasma (with less filament discharge) in a very small volume and a relatively extended plasma plume with a limitation of the gas temperature. Wettability measurements and tensile tests were carried out on 3D printed + plasma treated objects, obtained with our newly designed device. The material bonding is evaluated either within a single-material specimen by applying the treatment at the interlayers or within a multi-material one by treating only the interface layer of the two different materials.

SiCN thin film deposition by microwave plasma assisted chemical vapor deposition. Process and thin film characterisation in N2/Ar/CH4/H2/hexamethyldisilazane mixture

Les films à base de Si, C et N présentent de très intéressantes propriétés mécaniques, optiques et électroniques. L'objectif de ce travail est de mettre au point le procédé de dépôt chimique en phase vapeur assisté par plasma micro-onde permettant l'élaboration, à partir d'hexaméthyldisilazane (HMDSN), de films minces de SiCN dont l'indice de réfraction et le gap peuvent être modulés en modifiant des paramètres expérimentaux. Un mélange à base de N2/Ar/HMDSN permet le dépôt de films durs, adhérents et transparents. Ceux-ci sont de type SiNx:H avec une faible teneur en carbone (< 20%). L'ajout de CH4 dans le mélange plasmagène ne modifie pas de façon très importante la composition des films mais change fortement leur structure.L'utilisation d?un mélange H2/Ar/HMDSN à la place du mélange N2/Ar/HMDSN aboutit à des films de type SiCx:H avec une teneur en N inférieure à 15 %. Les films ont alors un indice plus élevé (2.15) et un gap modéré (3.5 eV). L'ajout d'une petite quantité de N2 (< 5 %) dans le mélange change radicalement la composition du film. Les films sont alors de type SiNx:H avec un indice de l'ordre de 1.95 et un gap de 4.5 eV. L'indice et le gap peuvent alors être liés au taux de liaisons Si-C dans le film.Ce changement abrupt est probablement dû à deux effets combinés. D'une part, le carbone en phase gazeuse réagit avec l'azote pour former des espèces stables (CN, HCN) qui participent peu à la croissance. D'autre part, Si se lie préférentiellement avec N pour former des films de type SiNx:H. Une modulation des constantes optiques des films de SiCN via le taux de C peut ainsi être réalisée par l'ajout de très faibles quantités de N2 dans le mélange gazeux H2/Ar/HMDSNThin films made of Si, C, and N exhibit promising properties such as high hardness or wide tunable bandgap. This study concerns the deposition of SiCN thin films by MPACVD, whose optical properties can be changed by varying experimental deposition conditions. A gaseous mixture made of N2/Ar/hexamethyldisilazane(HMDSN) allows the synthesis of hard and transparent coating. The deposited material is very close to those of amorphous hydrogenated silicon nitride, with rather low carbon content. Effects on the films of different experimental deposition parameters are explored. CH4 addition to the N2/Ar/HMDSN gaseous mixture does not widely modify the chemical composition but leads to denser and smoother layers. H2/Ar/HMDSN plasma instead of N2/Ar/HMDSN results in thin films with a high C content. Thin film composition is closed to SiCx:H with N content lower than 15 %. Refractive index is high (2.15) and band gap (3.5 eV) is closed to that of SiC material. Addition of a small quantity of N2 (5 %) to the gaseous mixture leads to a sharp atomic composition change. The deposited material is closed to SiNx:H and exhibits a refractive index of 1.95 and a bandgap of 4.5 eV. These large modifications could be related to Si-C cross-links density. This dramatic change is probably due to two combined effects. On one hand, carbon in gaseous phase reacts with nitrogen and produces stable products, in particular CN and HCN. On the other hand, Si preferentially links with N than with C what results in material close to silicon nitride. Wide modifications of SiCN thin films optical properties can thus be obtained by adding very low N2 flow in H2/Ar/HMDSN plasm

Synthèse de couches minces de SiCN par dépôt chimique en phase vapeur assisté par plasma micro-onde. Caractérisation du procédé et des films élaborés dans le mélange N2/Ar/CH4/H2/hexaméthyldisilazane

Thin films made of Si, C, and N exhibit promising properties such as high hardness or wide tunable bandgap. This study concerns the deposition of SiCN thin films by MPACVD, whose optical properties can be changed by varying experimental deposition conditions. A gaseous mixture made of N2/Ar/hexamethyldisilazane(HMDSN) allows the synthesis of hard and transparent coating. The deposited material is very close in his chemical composition and optical properties to those of amorphous hydrogenated silicon nitride, with rather low carbon content. Effects on the films of different experimental deposition parameters are explored. An increase of substrate temperature leads to a reduction of deposited thickness and NH density in the films. On the other hand, a higher content of Si-N cross-links is observed and results in an increase of refractive index. CH4 addition to the N2/Ar/HMDSN gaseous mixture does not widely modify the chemical composition but leads to denser and smoother layers. C content is not strongly enhanced and optical properties slightly change. H2/Ar/HMDSN plasma instead of N2/Ar/HMDSN results in thin films with a high C content. Thin film composition is closed to SiCx:H with N content lower than 15 %. Refractive index is high (2.15) and band gap (3.5 eV) is closed to that of SiC material. Addition of a small quantity of N2 (5 %) to the gaseous mixture leads to a sharp atomic composition change. The deposited material is closed to SiNx:H and exhibits a refractive index of 1.95 and a bandgap of 4.5 eV. These large modifications could be related to Si-C cross-links density. This dramatic change is probably due to two combined effects. On one hand, carbon in gaseous phase reacts with nitrogen and produces stable products, in particular CN and HCN. On the other hand, Si preferentially links with N than with C what results in material close to silicon nitride. Wide modifications of SiCN thin films optical properties can thus be obtained by adding very low N2 flow in H2/Ar/HMDSN plasma.Les films à base de Si, C et N présentent des propriétés mécaniques, optiques et électroniques intéressantes qui en font des matériaux prometteurs, notamment pour des applications optoélectroniques. L'objectif de ce travail est de mettre au point le procédé de dépôt chimique en phase vapeur assisté par plasma micro-onde permettant l'élaboration, à partir d'hexaméthyldisilazane (HMDSN), de films minces de SiCN dont l'indice de réfraction et le gap peuvent être modulés en modifiant des paramètres expérimentaux. Un mélange à base de N2/Ar/HMDSN permet le dépôt de films durs, adhérents et transparents. Ceux-ci sont de type SiNx:H avec une faible teneur en carbone (< 20%). L'influence de différents paramètres expérimentaux sur les couches minces élaborées dans ce mélange a été évaluée. Une augmentation de la température du porte substrat entraîne une réduction de l'épaisseur déposée, une diminution de la densité de groupements NH ainsi qu'une meilleure réticulation des films. Ceux-ci tendent alors vers un nitrure de silicium stoechiométrique et les indices des films augmentent de 1.6 à 1.8. L'ajout de CH4 dans le mélange plasmagène ne modifie pas de façon très importante la composition des films mais change fortement leur structure. Un mélange N2/CH4/Ar/HMDSN avec 6 % de CH4 permet ainsi d'obtenir des films denses et une rugosité réduite. L'incorporation de C n'est cependant que peu améliorée et les caractéristiques optiques restent voisines de celles de Si3N4. L'utilisation d'un mélange H2/Ar/HMDSN à la place du mélange N2/Ar/HMDSN aboutit à des films de type SiCx:H avec une teneur en N inférieure à 15 %. Les films ont alors un indice plus élevé (2.15) et un gap modéré (3.5 eV). L'ajout d'une petite quantité de N2 (< 5 %) dans le mélange change radicalement la composition du film. Le taux de C baisse fortement alors que celui de N augmente dans les mêmes proportions. Les films sont alors de type SiNx:H avec un indice de l'ordre de 1.95 et un gap de 4.5 eV. L'indice et le gap peuvent alors être liés au taux de liaisons Si-C dans le film. Ce changement abrupt est probablement dû à deux effets combinés. D'une part, le carbone en phase gazeuse réagit avec l'azote pour former des espèces stables (CN, HCN) qui participent peu à la croissance. D'autre part, Si se lie préférentiellement avec N pour former des films de type SiNx:H. Une modulation des constantes optiques des films de SiCN via le taux de C peut ainsi être réalisée par l'ajout de très faibles quantités de N2 dans le mélange gazeux H2/Ar/HMDSN

Wide variations of SiCxNy:H thin films optical constants deposited by H2/N2/Ar/hexamethyldisilazane microwave plasma

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Study of a pulsed post‐discharge plasma deposition process of APTES: synthesis of highly organic pp‐APTES thin films with NH 2 functionalized polysilsesquioxane evidences

International audienceThis article reports the use of pulsed remote Ar-O 2 microwave plasma assisted chemical vapor deposition with an −NH 2 containing organosilicon precursor ((3-Aminopropyl)triethoxysilane: APTES). It is shown that modifying the plasma pulses duration (t on) and the plasma off duration (t off) allows to finely tune the deposited layer composition. In addition, the results of this work demonstrate that an important film growth occurs during t off , which results in an increased −NH 2 density. Besides, high resolution MALDI-ORBITRAP Mass spectrometry analysis clearly points out that APTES oligomers up to eight base units, including silsesquioxanes (cages), and cyclosi-loxanes (rings) molecules with intact −NH 2 groups are embedded into the as grown pp-APTES thin film. K E Y W O R D S microwave discharges, plasma-enhanced chemical vapour deposition (PECVD), plasma polymerization, pulsed discharges, remote plasma processes

Facies relationships and cyclicity of high-latitude, Late Permian coal measures, Bowen Basin, Australia

The Late Permian Moranbah Coal Measures are developed throughout the northern and central Bowen Basin, eastern Australia, and are subject to large-scale opencut coal mining activity. They were deposited in a rapidly subsiding retroarc foreland basin, during frequent base-level changes. Contemporaneous compressive deformation and volcanism facilitated the supply of abundant volcanoclastic sediments, resulting in rapid, but punctuated, basinal aggradation. To the south and east, transgressive–regressive cycles were marked by the inter-digitation of paralic–shallow marine and alluvial strata. Lonestones (dropstones) are common within the marine deposits and are attributed to ice-rafting indicative of a cold-climate depositional regime. Two basin-wide chronostratigraphic units, the P-tuff bed and the Harrow Creek superseam, have been used to evaluate the facies architecture of the stratigraphic interval they enclose. The lithofacies mosaic of the 25–75 m thick sequence has been examined by means of 26 widely distributed coreholes and two detailed district-scale studies based around the Moranbah–Goonyella and German Creek minesites. Eight alluvial–shallow marine facies associations have been recognised. Their architectural and temporal relationships allow the accurate reconstruction of the coal-bearing depositional system. Two dissimilar, stacked, depositional systems tracts, A (organics) and B (clastics) are recognised. The P-tuff bed is enclosed by facies of tract A, forming a thick, low-ash, coal-bearing interval which was emplaced essentially synchronously across the basin. It represents a time of clastic sediment starvation when basin-wide peat mire accumulation prevailed. Four similar extensive coal-bearing intervals within the Moranbah Coal Measures are also considered to represent basin-wide episodes of peat accumulation. This pattern is in strong contrast to traditional views of coal measure development, which argue that coals formed within a contemporary facies mosaic, in which fluvial channels, levees and crevasse splays were also represented. The second depositional systems tract (B) is characterised by clastic packages, dominated by large-scale (up to 4 km wide and 50 m thick), sandstone bodies deposited by low sinuosity trunk river systems, flanked by substantial crevasse splay deposits (up to 3 km wide and 30 m thick). It represents the product of catastrophic flooding events. The cyclothemic succession of systems tracts A and B is interpreted in terms of eustatic sealevel cycles. The tract A coal-bearing intervals represent relative sealevel lowstands. Systems tract B represents relative sea level highstand with its lower interval at German Creek to the south consisting of paralic and marine facies. The cycles had durations in the order of 400 to 600 ky and are considered to represent 4th order sealevel cycles of the Permian Period