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1277 |
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Monday, June 02, 2008, Room 08 2:40 PM Plasma Spraying and Plasma Transferred Arc 1 New trends and modified plasma processes for the application of ceramic-based coatings |
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Gas permeability of porous plasma sprayed coatings |
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Karine Wittmann-Ténèze* / CEA Le Ripault, France Jean-Michel Pereira/ CEA Le Ripault, France Nadège Caron/ CEA Le Ripault, France |
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For different applications, it is on interest to understand the relationship between the microstructure and the transverse permeability of a plasma sprayed coating. In the SOFC field, for example, the electrodes are very often characterized in term of porosity. This characteristic is not relevant to understand the electrochemical performance of an electrode in SOFC working conditions; a better criterion is the gas permeability. For example, thermally sprayed coatings elaborated under different experimental conditions can have a large range of permeability with a same porosity rate partially because of their very singular microstructure, lamellar and isotropic, depending strongly on the initial material and plasma conditions. In this work, a correlation between plasma elaborating conditions and the permeability value is presented. Coatings have been manufactured by DC plasma spraying varying: plasma parameters, porous agent, powders proportions and two particles sizes in order to obtain various microporous structure. Permeation measurements with the pressure drop method, open porosity, observation of the morphology and the structure by scanning electron microscopy (SEM) have been achieved. The different data show that the evolution of the transverse permeability with the open porosity follows the Kozeny-Carman equation. This result correlated with the SEM images highlights the relationship between the permeability and the physical properties of porous plasma sprayed layers. |