The Influence of Dry Particle Coating Parameters on Thermal Coatings Properties

International audienceThe physical properties of coatings elaborated by plasma spraying, especially the mechanical properties are strongly influenced by some fifty operating parameters of the spraying process. Several studies have been conducted to correlate these operating parameters with the coating microstructure, via the behavior of molten particles in flight to be impacted against the surface substrate, well known as splats. Then, it is expected to build coatings with tailored properties for mechanical and even thermal applications (Fauchais & Vardelle, 2000). Simultaneously to the operating parameters of plasma spraying, characteristics of raw powder play an important role in the coating elaboration (Vaidya et al, 2001). Depending on the production process, particles feature different characteristics concerning shape, size, specific density, purity, etc. This has a significant influence on the resulting coating properties (Sampath et al, 1996). Consequently, it becomes mandatory to have an intensive knowledge about the powder characteristics in order to better control the behavior of inflight particles and, thus obtaining coatings with the expected performance. For the elaboration of composite coatings, it is commonly to use composite powders. However, different characteristics of powders are obtained from the variety of processes nowadays available for powder production, even for powders with the same chemical composition! (Kubel, 2000) Kubel has compared powders produced from different techniques for plasma spraying (atomization, agglomeration by spray-drying, melting and grinding, wet particle coating; sintering). A variety of powder characteristics is found for which the operating parameters for plasma spraying must be adapted to obtain deposits featuring the desired properties. From this, certain components or materials are fabricated by some of these methods or exclusively just one

Modelación matemática de la hidrodesintegración de fracciones de petróleo utilizando uno a seis lumps

The mathematical modeling of hydrocracking reaction of petroleum fractions was carried out considering a pseudohomogeneous phase. The discrete description was used to represent the kinetic of the reactions. Oneto 6 lumps of pseudocompounds with different reaction routes were used. Data from the oil hydrocarbon hydrocracking of literature were used to obtain the mathematical model parameters. Modeling more than one group or lump was done by automatic successive approach solving the system of equations starting with one lump, then two, then three, and so on, checking that the material balance is satisfied in each case. Findings showed concordance between the models and the experimental data, highlighting the use of six lumps, from whose description it is possible to determine the composition of the hydrocracking products in a detailed and reliable way.Se realizó la modelación matemática de la reacción de hidrodesintegración de fracciones de petróleo considerando una fase pseudohomogénea. Se empleó la descripción discreta para representar la cinética de las reacciones. Se utilizaron de uno hasta seis grupos de pseudocomponentes o lumps con diferentes rutas de reacción. Se utilizaron datos de la literatura de la hidrodesintegración de hidrocarburos de petróleo para obtener los parámetros de los modelos matemáticos. Para el modelo de más de un grupo o lump se utilizó la aproximación sucesiva automática, resolviendo el sistema de ecuaciones comenzando con un lump, dos, o tres y así sucesivamente, verificando que siempre se cumpliera el balance de materia. Se encontró buena concordancia entre el modelo y los datos experimentales para las aproximaciones utilizadas, destacando el uso de seis lumps, a partir de cuya descripción es posible determinar la composición de los productos de hidrodesintegración de una forma detallada y confiable

Modelación matemática de un reactor de tanque agitado con catalizador disperso para la obtención de metil oleato a partir de trioleína

The mathematical modeling of a three-phase reactor with dispersed phase catalyst for production of methyl oleate was carried out. Mass balances were used at the reactor level as well as the fluid-catalyst interphase to represent the operation system. The effect of type, particle size and catalyst concentration, as well as space-time and arrangement of reactors in series were examined. The purity of the triglyceride in the feeding was also investigated. The factors that most affected the reactor behavior quantitatively were the concentration of the catalyst, and its type, as well as the series arrangement of two reactors at constant space-timeSe realizó la modelación matemática de un reactor trifásico con catalizador en fase dispersa para la producción de metil oleato. Se uti-lizaron balances de materia a nivel reactor, así como entre fase fluida-catalizador para representar la operación del sistema. Se investigó el efecto del tipo, tamaño de partícula y concentración del catalizador, así como espacio-tiempo y arreglo de reactores en serie. Asimismo, se investigó sobre la pureza del triglicérido en la alimentación. Los factores que más afectaron cuantitativamente el desempeño del reactor fueron la concentración del catalizador, su tipo y el arreglo en serie de dos reactores a espacio-tiempo constante