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Chemical Stability Durability

In the modern world, we are accustomed to taking the chemical stability of glass very much for granted - we rely on the durability of glass for so many things, such as windows and (until the widespread availability of plastics) bottles, as well as its use in the chemical laboratory as an extremely inert and unreactive container. In addition to its apparent inertness, glass has a number of other beneficial properties, such as its transparency or the ability to take on virtually any colour as the result of the addition of a small amount of transition metals. [Pg.144]

The two parts of these performance specifications are reflected in the term permanent/durable that began to be used to identify such papers. Durability is the level of physical strength and flexibility necessary to withstand extensive use and handling. Permanence indicates a degree of chemical stability that permits only very slow deterioration. [Pg.50]

The stability and durability of Pt alloys, especially those involving a >d transition metal, are the major hurdles preventing them from commercial fuel cell applications. "" The transition metals in these alloys are not thermodynamically stable and may leach out in the acidic PEM fuel cell environment. Transition metal atoms at the surface of the alloy particles leach out faster than those under the surface of Pt atom layers." The metal cations of the leaching products can replace the protons of ionomers in the membrane and lead to reduced ionic conductivity, which in turn increases the resistance loss and activation overpotential loss. Gasteiger et al. showed that preleached Pt alloys displayed improved chemical stability and reduced ORR overpotential loss (in the mass transport region), but their long-term stability has not been demonstrated. " These alloys experienced rapid activity loss after a few hundred hours of fuel cell tests, which was attributed to changes in their surface composition and structure." ... [Pg.265]

This strategy may be realized by the use of reactive oligomers (RO), i.e. low-molecular weight compounds which may be converted to polymers of linear, branched, ladder and three-dimensional network structures. Of special importance are RO s which form cross-linked polymers since in this case materials with optimal values of heat and fire resistance, strength, chemical stability, atmospheric resistance, durability, etc. may be obtained. [Pg.5]

Granite is most commonly used in applications where physical stability, durability and strength in a mildly acid environment are required. Historical uses of granite as a chemically resistant masonry include its use as flooring in places where "oil of vitriol" (sulfuric acid) was made. In the nineteenth century, granite blocks hollowed out to form tubs were employed by steel wire companies to hold dilute HCI baths for pickling off mill scale from the wire. Some of these tubs are still in use today. [Pg.224]

An excellent thermal and chemical stability, for PEMFC reliability and durability. [Pg.338]

System design, performance and cost of such SOFC depend on the properties of innovative materials and advanced ceramics. The careful design and manufacture of these materials is essential to system integration and performance, and may ultimately determine the success or failure of the technology. Important factors include stability, durability, processibility catalytic, electro-chemical and ionic properties. Figure 9-24 shows SEM image of ceramic layers used in a SOFC cell. [Pg.235]


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