Stability alumina-based ceramics

Fig. 2.72 The influence of the temperature, T (diagrams a, c, e) at V h = 0.5 mm/min and of the speed V<-h, (diagrams b, d, f) at T = 1200 °C on the appearance of the load (P) versus deflection <5 a, b SN-1 c, d A-1 e, f Y-PSZ-3. SN-1 is a silicon nitride-based ceramic with additions of Y2O3 and AI2O3 A-1 is an alumina-based ceramic with an addition of MgO and Y-PSZ-3 is a Y2O3 stabilized zirconia based single crystal [18]. With kind permission of Elsevier...

Catalysts for both the applications described above have been prepared on particulate and monolithic supports. For this investigation, all catalysts were prepared on a commercially available, monolithic support from American Lava. A coating of high surface area, stabilized alumina was applied to the ceramic, and it was then impregnated. Ruthenium or a ruthenium alloy catalyst (Engelhard N-2) was used for the reduction catalyst whereas ruthenium was not used for the TWC catalyst (TWC-1). In all preparations containing ruthenium, the loading was such that annual availability was not exceeded based on the assumption that all cars sold in the United States contained the catalyst. 

Afterburning processes enable the removal of pollutants such as hydrocarbons and volatile organic compounds (VOCs) by treatment under thermal or catalytical conditions. Combinations of both techniques are also known. VOCs are emissions from various sources (e.g. solvents, reaction products etc. from the paint industry, enaml-ing operations, plywood manufacture, printing industry). They are mostly oxidized catalytically in the presence of Pt, Pd, Fe, Mn, Cu or Cr catalysts. The temperatures in catalytic afterburning processes are much lower than for thermal processes, so avoiding higher NOx levels. The catalysts involved are ceramic or metal honeycombs with washcoats based on cordierite, mullite or perovskites such as LaCoOs or Sr-doped LaCoOs. Conventional catalysts contain Ba-stabilized alumina plus Pt or Pd. 

The metal catalysts active for steam reforming of methane are the group VIII metals, usually nickel. Although other group VIII metals are active, they have drawbacks for example, iron rapidly oxidizes, cobalt cannot withstand the partial pressures of steam, and the precious metals (rhodium, ruthenium, platinum, and palladium) are too expensive for commercial operation. Rhodium and ruthenium are ten times more active than nickel, platinum, and palladium. However, the selectivity of platinum and palladium are better than rhodium [1]. The supports for most industrial catalysts are based on ceramic oxides or oxides stabilized by hydraulic cement. The commonly-used ceramic supports include a-alumina, magnesia, calcium-aluminate, or magnesium-alu-minate [4,8]. Supports used for low temperature reforming (< 770 K) are... 

Another approach extensively apphed in recerrt years to improve the ion conductivity ((, lithiirm ion transference number (C), mechanical properties, and the electrode-electrolyte interfacial stability of a polymer electrolyte is the addition of inorganic or ceramic fillers into the polymer-salt complexes (Capiglia et al., 1999 Kim et al., 2003 Chen-Yang et al., 2008 Croce et al., 2001 Rahman et al., 2009 Shen et al., 2009 Zhang et al., 2011 Munichandratah et al., 1995 Wiec-zorek, 1992). Micro and nano-sized inorganic filler such as silicone oxide (SiO ), alumina (AI2O3), ceria (CeO ), and so on are incorporated into PEO-salt complex in an effort to improve the mechanical, thermal stabihty, and ion conductivity of PEO-based polymer electrolytes. The effect of nano-fillers on the thermal properties of the PEO-based polymer complex varies with the type of nano-particles as well as the polymer-salt complex host matrix. 

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