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Olivier Dufaud

Bio: Olivier Dufaud is an academic researcher from University of Lorraine. The author has contributed to research in topic(s): Dust explosion & Ignition system. The author has an hindex of 21, co-authored 80 publication(s) receiving 1396 citation(s). Previous affiliations of Olivier Dufaud include Nancy-Université & Centre national de la recherche scientifique.
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Journal ArticleDOI
TL;DR: It is found that as the particle size decreases, minimum ignition temperature (MIT) and minimum ignition energy (MIE) decrease, indicating higher potential inflammation and explosion risks for the use of nanopowders.
Abstract: Characterization methods with regard to nanopowder flammability and explosivity are presented and illustrated for few nanopowders. Analytical models are developed in order to explain the dependency of the combustion times on the particle diameter. Experimental evidence shows that there exists, for carbonaceous and metallic materials, mainly two combustion regimes that are either kinetically controlled, for small size particles, or diffusion controlled, for large size particles. From the experimentally measured combustion data of those materials, the dependencies of the ignition temperature and the minimal explosive concentration (MEC) with regard to the particle size have been analyzed. We found that the two combustion regimes yield two different tendencies with respect to the particle size. Overall, it is found that as the particle size decreases, minimum ignition temperature (MIT) and minimum ignition energy (MIE) decrease, indicating higher potential inflammation and explosion risks for the use of nanopowders. By contrast, the minimal explosion concentration (MEC) did not show strong variations as the particle size decreases. Rather, a theoretical plateau is observed, which was experimentally confirmed. We also observed that carbon nanopowders exhibit a low propensity to explode while metallic nanopowders can be very reactive, thus delineating high potentials for explosion risks in manufacturing facilities.

152 citations

Journal ArticleDOI
Abstract: An experimental investigation was carried out on the influences of dust concentration, particle size distribution and humidity on aluminum dust explosion. Tests were mainly conducted thanks to a 20 L explosion sphere. The effect of humidity was studied by storing the aluminum particles at constant relative humidity until the sorption equilibrium or by introducing water vapour in the explosion vessel. The tested particles sizes ranged from a volume median diameter of 7 to 42 μm and the dust concentrations were up to 3000 g m−3. Among other results, the strong influence of the particle size was pointed out, especially when the Sauter mean diameter is considered. These results stressed the predominance of the specific surface area on the mass median particle diameter. The effect of water on aluminum dust explosion was decoupled: on the one hand, when water adsorption occurs, hydrogen generation leads to an increase of the explosion severity; on the other hand, when the explosion of dried aluminum powder occurs in a humid atmosphere, the inhibiting effect of humidity is put forward. A model based on mass and heat balances, assuming a shrinking core model with chemical reaction limitation, leads to a satisfactory representation of the pressure evolution during the dust explosion.

92 citations

Journal ArticleDOI
S. Calle1, L. Klaba1, Dominique Thomas1, Laurent Perrin1  +1 moreInstitutions (1)
29 Sep 2005-Powder Technology
Abstract: The explosion ability of wood dust was characterized by a 20 L explosion sphere (Kuhner). The overpressure inside the sphere is recorded during the explosion. The results show that the violence of the explosion is all the more important that the particle size is low. A model based on balances on chemical reaction, kinetics and thermodynamics leads to the representation of the pressure change during the explosion. There is a good agreement between the calculations and the experiments.

79 citations

Journal ArticleDOI
Abstract: This article underlines the peculiar behaviour of hybrid mixtures towards explosions. It should notably be noticed that there are more than additive effects on explosions severity, especially on the maximum rate of pressure rise. Moreover, the evolution of the maximum explosion pressure as a function of combustibles concentrations shows that the impact of hybrid mixtures is perceptible even for vapour amounts or dust concentrations lower than the explosion limits of the pure compounds.

62 citations

Journal ArticleDOI
05 Mar 2009-Powder Technology
Abstract: The aim of this work is to demonstrate the particular aspects of the explosion of hybrid mixtures with respect to either vapour or dust explosions. This work is focused on pharmaceutical products from excipients to active drug substances and their associated solvents. Experiments with an explosion sphere has been used to determined the influence of dusts and vapours concentrations on the severity of explosions (maximum pressure Pmax and maximum rate of pressure rise (dP/dt)max). Results clearly show that the explosion behaviour of such hybrid mixtures reveals significant differences with respect to either vapour or dust explosions; especially a promotion effect on the combustion kinetics and on the rate of pressure rise for poor mixtures. The influences of the introduction of small amount of vapour on the minimum explosible dust concentration (MEC) and of dust addition on the lower explosion limit (LEL) are noteworthy.

59 citations

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Journal ArticleDOI
Nannan Guo1, Ming-Chuan Leu1Institutions (1)
Abstract: Additive manufacturing (AM) technology has been researched and developed for more than 20 years. Rather than removing materials, AM processes make three-dimensional parts directly from CAD models by adding materials layer by layer, offering the beneficial ability to build parts with geometric and material complexities that could not be produced by subtractive manufacturing processes. Through intensive research over the past two decades, significant progress has been made in the development and commercialization of new and innovative AM processes, as well as numerous practical applications in aerospace, automotive, biomedical, energy and other fields. This paper reviews the main processes, materials and applications of the current AM technology and presents future research needs for this technology.

1,148 citations

Journal ArticleDOI
Abstract: New microproducts need the utilization of a diversity of materials and have complicated three-dimensional (3D) microstructures with high aspect ratios. To date, many micromanufacturing processes have been developed but specific class of such processes are applicable for fabrication of functional and true 3D microcomponents/assemblies. The aptitude to process a broad range of materials and the ability to fabricate functional and geometrically complicated 3D microstructures provides the additive manufacturing (AM) processes some profits over traditional methods, such as lithography-based or micromachining approaches investigated widely in the past. In this paper, 3D micro-AM processes have been classified into three main groups, including scalable micro-AM systems, 3D direct writing, and hybrid processes, and the key processes have been reviewed comprehensively. Principle and recent progress of each 3D micro-AM process has been described, and the advantages and disadvantages of each process have been presented.

891 citations

Journal ArticleDOI
Abstract: This paper offers a review of present achievements in the field of processing of ceramic-based materials with complex geometry using the main additive manufacturing (AM) technologies In AM, the geometrical design of a desired ceramic-based component is combined with the materials design In this way, the fabrication times and the product costs of ceramic-based parts with required properties can be substantially reduced However, dimensional accuracy and surface finish still remain crucial features in today's AM due to the layer-by-layer formation of the parts In spite of the fact that significant progress has been made in the development of feedstock materials, the most difficult limitations for AM technologies are the restrictions set by material selection for each AM method and aspects considering the inner architectural design of the manufactured parts Hence, any future progress in the field of AM should be based on the improvement of the existing technologies or, alternatively, the development of new approaches with an emphasis on parts allowing the near-net formation of ceramic structures, while optimizing the design of new materials and of the part architecture

451 citations

Journal ArticleDOI
TL;DR: Key additive manufacturing methods are first introduced followed by AM of different materials, and finally applications of AM in various treatment options are reviewed.
Abstract: Biomaterials are used to engineer functional restoration of different tissues to improve human health and the quality of life. Biomaterials can be natural or synthetic. Additive manufacturing (AM) is a novel materials processing approach to create parts or prototypes layer-by-layer directly from a computer aided design (CAD) file. The combination of additive manufacturing and biomaterials is very promising, especially towards patient specific clinical applications. Challenges of AM technology along with related materials issues need to be realized to make this approach feasible for broader clinical needs. This approach is already making a significant gain towards numerous commercial biomedical devices. In this review, key additive manufacturing methods are first introduced followed by AM of different materials, and finally applications of AM in various treatment options. Realization of critical challenges and technical issues for different AM methods and biomaterial selections based on clinical needs are vital. Multidisciplinary research will be necessary to face those challenges and fully realize the potential of AM in the coming days.

314 citations

Journal ArticleDOI
Abstract: In recent years, additive manufacturing, also known as three-dimensional (3D) printing, has emerged as an environmentally friendly green manufacturing technology which brings great benefits, such as energy saving, less material consumption, and efficient production. These advantages are attributed to the successive material deposition at designated target areas by delivering the energy on it. In this regard, lasers are the most effective energy source in additive manufacturing since the laser beam can transfer a large amount of energy into micro-scale focal region instantaneously to solidify or cure materials in air, therefore enabling high-precision and high-throughput manufacturing for a wide range of materials. In this paper, we introduce laser-based additive manufacturing methods and review the types of lasers widely used in 3D printing machines. Important laser parameters relevant to additive manufacturing will be analyzed and general guidelines for selecting suitable lasers for additive manufacturing will be provided. Discussion on future prospects of laser technologies for additive manufacturing will be finally covered.

170 citations

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Author's H-index: 21

No. of papers from the Author in previous years