Effect of Gaseous Environment

Different metals behave differently when heated in H2. Fiederow et a/.248 have found that the resistance to sintering decreases in the order Ir Rh Pt, which is in approximate agreement with the order calculated.23 The decrease in dispersion after heating at 1073 K for 16h248 was found to be 20% (Ir), 40% (Rh), and 55% (Pt). 

The discrepancy between the results of Fiederow et al. and of Chu and Ruckenstein may be related to the method used to prepare the catalysts. Thus, Chu and Ruckenstein comment that industrial catalysts sinter rapidly 

At 773 K the equilibrium pressure is 0.08 bar, i.e., higher than the 02 pressure used by Smith et al. Another possible factor is that the level of impurities in the work of Smith et al. may have been lower, so sintering was not inhibited. 

Research , 13 (Sintering Processes), Plenum Press, New York, 1980, p. 561. 

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Table 14.5 Effect of Gaseous Environment on the Wear Lives of Molybdenum Disulphide and Graphite Fluoride Films (Ref. 132)...

The effect of gaseous environments on the morphology of electrospun nanofibers reported. 

Note that the term Pi i ) in the denominator of the first term in Equation (17) reflects many-body effects of the environment, which also spoil the symmetry between indices / and s of the expression for lis in gaseous systems, is an extrapolation of... 

In this part we dwell on the properties of the simplest radicals and atoms in the adsorbed layer of oxide semiconductors as well as analyse the quantitative relationships between concentrations of these particles both in gaseous and liquid phases and on oxide surfaces (mostly for ZnO), and effect of former parameters on electrophysical parameters. Note that describing these properties we pursue only one principal objective, i. e. to prove the existence of a reliable physical and physical-chemical basis for a further development and application of semiconductor sensors in systems and processes which involve active particles emerging on the surface either as short-lived intermediate formations, or are emitted as free particles from the surface into the environment (heterogeno-homogeneous processes). 

Zaman M, Blennerhassett JD. Effects of the different rates of urease and nitrification inhibitors on gaseous emissions of ammonia and nitrous oxide, nitrate leaching and pasture production from urine patches in an intensive grazed pasture system. Agriculture Ecosystems and Environment. 2010 136 236-246. 

Following early ETEM investigations using environmental cells, environmental scanning electron microscopy (ESEM) has been developed for characterization of surface effects of bulk SEM samples in the presence of gaseous or wet environments (111-114). The method has been applied to the examination of food, wool fibers (111), and polymers (112) and in the conservation of cultural properties (113). Recently, fuel cell catalysts have been characterized using a low-voltage ESEM with a resolution capability of 2 nm (114). 

Kale PG, Baum JW. 1981. Sensitivity of Drosophila melanogaster to low concentrations of gaseous mutagens III. Dose-rate effects. Environ Mutagen 3 65-70. 

Prentice et al (Ref 2) report on the use of a Xe flash lamp appar (Fig 1) as an ign source and combstn environment to study the ignite-ability, burning mode and time-to-expln of various metal fuels. The lamp appar is used as a rocket motor environment simulation in this investigation to explore the effect of particle size (200 to 500 microns), changing the gaseous atm, and varying the pressure regimes on metal fuels such as Al, B, Be, Mg, Ti and Zr... 

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