Ceramic multi-layer

Rgure 7.2 shows the design of a thermoelectric gas sensor device manufactured according to planar ceramic multi-layer technology.The heater brings the tip of the sensor to operation temperature by applying a heater voltage,... 

The ceramic multi-layer coating effectively confines fission products at 1400°C for a long period and at 1600°C in the course of a few hours. At such temperatures the removal of residual heat can be performed by natural convection, conduction and radiation on a passive basis. Given the characteristic coated particle size (the diameter of 2-4 mm), the heat from coated particle fuel is transferred to the coolant with a delay of only 0.1 s. Therefore, the core of a reactor with boiling water coolant that directly cools such coated fuel particles would provide a very rapid self-compensation of practically any positive reactivity if it is introduced not faster than in 0.1 s. 

Fabrication processing of these materials is highly complex, particularly for materials created to have interfaces in morphology or a microstructure [4—5], for example in co-fired multi-layer ceramics. In addition, there is both a scientific and a practical interest in studying the influence of a particular pore microstructure on the motional behavior of fluids imbibed into these materials [6-9]. This is due to the fact that the actual use of functionalized ceramics in industrial and biomedical applications often involves the movement of one or more fluids through the material. Research in this area is therefore bi-directional one must characterize both how the spatial microstructure (e.g., pore size, surface chemistry, surface area, connectivity) of the material evolves during processing, and how this microstructure affects the motional properties (e.g., molecular diffusion, adsorption coefficients, thermodynamic constants) of fluids contained within it. 

U.S. Department of Energy, Broad Agency Announcement (BAA)No. DE-BA26-99FT40274 for research entitled Multi-Layer Ceramic Fuel Cell Research , 7 June, 1999. 

Multi-Layer Ceramic Conceptual Design for RHFC... 

A multi-layer module 18 consisting of thin insulating wafers 20 formed from a ceramic material is prepared. The wafers have a large number of thin film electrically-conducting leads on their surfaces. The leads end at points 22 located on the focal plane surface 24 of the module. The lengths of the ceramic wafers are staggered to give access to lead pads 26 on the face of each wafer. 

In the preparation of multi-layered ceramic membranes, the quality of the support is of crucial importance to the integrity of the membrane layers that are applied in the subsequent preparation steps. First, the surface roughness and homogeneity of the support will determine the integrity of these membrane layers, and, second the surface roughness determines the minimal thickness of the membrane layer for complete surface coverage. 

The matching of expansion behavior is of the utmost importance to manufacturers of, for example, multi-layer capacitors, porcelain enameled cast iron sinks, fiber reinforced composites, light bulbs, etc. In all cases, various materials in rigid contact must have their expansion characteristics carefully matched. Inattention to this runs the risk of cracking and shattering of a light bulb at its seal to aluminum, delamination of metallic conductive leads from the ceramic substrate in a hybrid circuit, etc. By changing the composition of a constituent material, its... 

Multi-layered high-quality ceramic membranes do not have any appreciable pore blockage by the precursor particles from the adjacent layers. This is evidenced by the sharp and clean interface between layers shown in Figure 4.2. It should also be noted that the smoothness of the underlying layer is critical to forming a smooth layer on top of iL... 

Many commercial ceramic membranes have two three or even four layers in structure and their pore size distributions are similar to that shown in Figure 4.12. It should be noted, however, that determination of those multi-layered, broad pore size distributions is not suaightforward. The major reason for this is the overwhelmingly small pore volume of the thin, fine pore membrane layer compared to those of the support layer(s) of the structure. It is possible, although very tedious, to remove most of the bulk support layer to increase the relative percentage of the pore volumes of the membrane and other thin support layers. Provided the amount of bulk support layer removed is known and the mercury porosimeu data of the "shaved" membrane/support sample is determined, it is feasible to construct a composite pore size distribution such as the one shown in Figure 4.12. 

The architecture of the ceramic membrane system is that of a multi-layer asymmetric system (Figs. 9.2C and 9.3). The separation activity is concentrated mainly in the top layer, the other parts form the supporting systems with... 

Szymezyk, A. et al.. Determination of the filtering layer electrokinetic properties of a multi-layer ceramic membrane, Desalination, 116, 81, 1998. 

Quemard L., Rebillat F., Guette A., Tawil FI. and Louchet-Pouillerie C. Self-healing Mmechanisms of a SiC Fiber Reinforced Multi-layered Ceramic Matrix Composite in Hhigh Pressure Steam Environments // J. Eur. Ceram. Soc. 2007. V. 27. No 4. P. 2085-20W. 

Q. Ludovic, R. Francis, G. Alain, T. Flenri, and L. Caroline, Self-healing mechanisms of a SiC fiber reinforced multi-layered ceramic matrix composite in high pressure steam environments, J. Eur. Ceram. Soc. 27[4], 2085-2094(2007). 

Violante et al. [51] simulated multi-layer membrane reactor for WGS reaction. They proposed that the permeability of the multi-layer metallic/ceramic membrane is higher than that of a traditional metallic membrane. With same pressure difference across the membrane and with the same exchange area, the hydrogen flux through the multi-layer membrane is five times larger than the flux through a Pd-Ag membrane. They also proposed that the membrane should operate at suitable temperature and pressure. 

In addition to such polymeric materials, inorganic (ceramic) materials have also been used for ultrafiltration membranes, especially alumina (AljC ) and zirconia (ZiOo), Figure VI -8 shows a multi-layer AI2O3 membrane in which the tOplayer is prepared via a sol-gel technique [6). 

Currently, transducer arrays are formed by ceramic polymer composite elements. A variety of technical solutions have been applied to improve their mechanical characteristics. In particular, piano-concave elements can be used to provide a uniform elevation plane radiation pattern both in the near and in the far field (Jedrzejewicz 1999). Similar results have been obtained producing multi-layered piezoelectric elements (Whittingham 1999b) or shaping the elements in other suitable ways. These refinements led to the use of very short pulses, increased bandwidth and better intrinsic collimation of the ultrasound beam (Fig. 1.1). 

Micro fuel elements with multi-layer ceramic coatings capable to confine fission products effectively at temperatures up to 1600 C ... 

Fuel type Spherical graphite fuel elements with coated fuel particles (spherical particles with UO2 kernels and multi-layer ceramic coatings)... 

Koslowske, M., A Process Based Cost Model for Multi-Layer Ceramic Manufacturing of Solid Oxide Fuel Cells, in Materials Science. 2003, Worcester Polytechnic Institute Worcester, MA, USA. p. 42. 

Swartz, S.L., Low Cost Manufacturing of Multi-Layer Ceramic Fuels,"" paper presented at Solid State Energy Conversion Alliance 2nd Annual Workshop Proceedings, March 2001, http //www.netl.doe.gov/publications/proceedings/01/seca/swartz.pdf... 

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