Zirconia calcium stabilized

The basic elements of a SOFC are (1) a cathode, typically a rare earth transition metal perovskite oxide, where oxygen from air is reduced to oxide ions, which then migrate through a solid electrolyte (2) into the anode, (3) where they combine electrochemically with to produce water if hydrogen is the fuel or water and carbon dioxide if methane is used. Carbon monoxide may also be used as a fuel. The solid electrolyte is typically a yttrium or calcium stabilized zirconia fast oxide ion conductor. However, in order to achieve acceptable anion mobility, the cell must be operated at about 1000 °C. This requirement is the main drawback to SOFCs. The standard anode is a Nickel-Zirconia cermet. 

The reactions between cerium trichloride and oxide ions were initially studied in the pure KCl-NaCl equimolar mixture at 1000 K by the method of potentiometric titration using a calcium-stabilized zirconia membrane electrode. The titration curves clearly demonstrated the existence of the soluble cerium oxychloride CeO+ and precipitated cerium oxide ... 

Metal halides have also been used as CVD precursors to YBCO films by Ottosson et al. at the University of Uppsala [I87. The sublimation temperatures of the YCI3, Bah. and CuCI precursors were 820°C, 950 C, and 340 C. respectively. These were used in combination with gaseous H2O/O2 at 20Torr in the deposition chamber to grow c-axis oriented YBCO films in situ on calcium stabilized zirconia substrates at 750-950°C. The YBCO films exhibited 7 . = 40 K [187]. 

The tubular design is probably the best-known design. It has been developed by Westinghouse (now Siemens Power generation) [8]. The first concept that was pursued by Westinghouse consisted of an air electrode supported fuel cell tube. In earlier days the tubes were made from calcium-stabilized zirconia on which the active cell components were sprayed. Nowadays this porous supported tube (PST) is replaced by a doped lanthanum manganite (LaMn) air electrode tube (AES) that increases the power density by about 35 %. The LaMn tubes are extruded and sintered and serve as the air electrode. The other cell components are deposited on this construction by plasma spraying. 

Anion Vacancies If the cation of the host structure has a higher charge than the replacing cation, electroneutrality may be maintained by introducing vacancies into the anion sublattice. The best-known examples of anion vacancies occur in the stabilized zirconia, such as calcium- or yttrium-stabilized zirconia. The high-temperature... 

Carter JD, Appel CC, and Mogensen M. Reactions at the calcium doped lanthanum chromite-yttria stabilized zirconia interface. J. Sol. St. Chem. 1996 122 407—415. 

Kowalski K, Bemasik A, Sadowski A. Diffusion of calcium in yttria-stabilized zirconia ceramics. J Eur Ceram Soc 2000 20 2095-100. 

The calcium fluoride was obtained as CP grade with a purity of 99.975 % from Fisher Scientific Company. Its average particle size was 0.3 jx. Stabilized zirconia, a cubic form of zirconia containing 3 to 7 % CaO, which does not have a phase transformation, was available in the form of hollow spheres. It was crushed and ground. The particle size fraction finer than 5 fx was separated out and used as marker material. 

The calcium fluoride and stabilized zirconia were blended in a cone blender for 12 hr and then ball milled for 24 hr in a cemented carbide mill with steel balls. Most zirconia particles were well distributed, although agglomeration could be observed in a few places, as will be seen in the photomicrographs. 

The stability of ceramic materials at high temperatures has made them useful as furnace liners and has led to interest in ceramic automobile engines, which could endure overheating. Currently, a typical automobile contains about 35 kg of ceramic materials such as spark plugs, pressure and vibration sensors, brake linings, catalytic converters, and thermal and electrical insulation. Some fuel cells make use of a porous solid electrolyte such as zirconia, Zr02, that contains a small amount of calcium oxide. It is an electronic insulator, and so electrons do not flow through it, but oxide ions do. 

Zirconia, calcium oxide stabilized, 5 622 strength, 5 617t Zirconia ceramics... 

The sol formation step can be carried out by precipitating a hydroxide with ammonia, which is then washed and dispersed as a sol by peptizing the slurry while controlling the pH. A 3.5 M zirconia sol, prepared by dispersing zirconium hydroxide in a dilute acid and then adding calcium or yttrium salt solutions, produces Y203-stabilized... 

In the present communication we report the regularities in the preparation of high surface area zirconia-based solid composites stabilized by calcium and barium, as well as the structural and catalytic properties of materials obtained by their sulfation. 

Zirconium dioxide, zirconia, is the only oxide of zirconium stable chemically at temperatures below 2000 K. At higher temperatures some dissociation into ZrO and oxygen takes place. The phases of ZrOj, their densities, and phase-transition temperatures are listed in Table 7.5. Zirconia stabilized in the high-temperature cubic phase by addition of 3 to S percent calcium oxide is used as a refractory at temperatures up to 2200° C. ZrOj has been used to dilute UOj in fuel elements. 

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