Ceramics dense

The shaping of these fine, submicrometer powders into complex components and their subsequent consoHdation into dense ceramic parts of ideally zero porosity is a major technological challenge. The parts formed need to be consoHdated to near-net shape because Si N machining requires expensive diamond grinding. Additionally, Si N dissociates at or near the typical densiftcation temperatures used in the fabrication of stmctural ceramics and, therefore, special measures have to be taken to preserve the compositional integrity of the material. 

B.C.H. Steele. Dense Ceramic ion conducting membranes in Oxygen ion and mixed conductors and their technological applications, (1997) Erice, Italy Kluwer. 

It is well known that dense ceramic membranes made of the mixture of ionic and electron conductors are permeable to oxygen at elevated temperatures. For example, perovskite-type oxides (e.g., La-Sr-Fe-Co, Sr-Fe-Co, and Ba-Sr-Co-Fe-based mixed oxide systems) are good oxygen-permeable ceramics. Figure 2.11 depicts a conceptual design of an oxygen membrane reactor equipped with an OPM. A detail of the ceramic membrane wall... 

Balachandran, U. et al., Dense ceramic membranes for partial oxidation of methane to syngas, Appl. Catal, 133, 19, 1995. 

Dense ceramic ion High selectivity for hydrogen Low permeability for hydrogen Laboratory scale... 

Balachandran, U., Development of Dense Ceramic Membranes for Hydrogen Separation, Proceedings of2005 U.S. DOE Hydrogen Annual Merit Review Meeting, Arlington, VA, May 2005. 

Balachandran, U., T.H. Lee, S. Wang, G. Zhang, and S.E. Dorris, Current Status of Dense Ceramic Membranes for hydrogen Separation, 27th International Technical Conference on Coal Utilization and Fuel Systems, Clearwater, FL, March 2002. 

Lin, J.Y.S., Proton conducting dense ceramic membranes for hydrogen separation, Annual Progress Report, U.S. DOE Contract DE-FG26-00NT40818, December 2002. 

Other fluoridation agents can be involved. After 2 h at 900°C, fully fluoridated apatite (a = 2) is formed [115]. Applying this process to HA-dense ceramics leads to similar results. 

Dense ceramics (bar), porous ceramics (cylinder), teeth anchorings (by J.Aarsen)... 

In The Netherlands the firm Cam Implants in Leiden manufactures a series of implants on the basis of HA, among which bio-active coatings on orthopaedic and dental implants, implants for the small bones of the middle ear, which are made of dense ceramics, porous ceramics for the middle ear and jaw and facial implants. The latter are e.g. small blocks to fill holes resulting from the removal of cysts and tumours. 

The bipolar plate design is illustrated in Fig. 47. It consists of a cross-flow arrangement where the gas-tight separation is achieved by dense ceramic or metallic plates with grooves for air and fuel supply to the appropriate electrodes. A porous cathode, a dense and thin electrolyte and a porous anode form a composite flat layer placed at the top of the interconnected grooves. The deposition of the porous electrodes can be achieved by mass production methods. Moreover, the bipolar plate configuration technology makes it possible to check for defaults, independently and prior to assembly of the interconnection plate and the anode-electrolyte-cathode structure. 

La0 2Sro8Feo55Tio 4503 8 (LSFTO) powder, synthesized by using the spray pyrolysis method, was obtained from Praxair Specialty Ceramics (Woodinville, WA). The powder was preheated at 1250°C for 10 h in air with a 3°C/min ramp rate. The preheated powder was ground with ethanol in a mortar for more than 30 min. After drying to remove the ethanol, the powder was pressed into a cylindrical shape at 5000 psi with a 1 in. diam die. Dense ceramic disks were obtained by sintering in air at 1300°C for 20 h and 1400°C for 10 h. The sintered disks had a density of 90.3% of the theoretical den-... 

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