Micron diameter range

He studied the sintering of copper particles in the diameter range 15-100 microns and of silver particles of diameter 350 microns. The results for the larger volume fraction of copper and for silver were shown to fit the volume diffusion mechanism and yielded the results for volume self-diffusion... 

Since metals are less electrophilic than silicon, metal oxide adsorbents show even stronger selectivity for polar molecules than do siliceous materials. The most commonly used metal oxide adsorbent is activated alumina, used primarily for gas drying. Occasionally, metal oxides find applications in specific chemisorption systems. For example, several processes are under development utilizing lime or limestone for removal of sulfur oxides from flue gases. Activated aluminas have surface areas in the range of 200 to 1000 ft2/ft3. Average pore diameters range from about 30 to 80 microns. 

For membranes with pore diameters smaller than 3.5 nm, the nitrogen adsorption/desorption method based on the widely used BET theory ean be employed. This measurement technique, however, is good only for pore diameters ranging from 1.5 nm to 100 nm ( = 0.1 micron). Typical data from this method are split into two portions adsorption and desorption. The nitrogen desorption curve is usually used to describe the pore size distribution and corresponds better to the mercury intrusion curve. Given in Figure... 

It is seen from figure (1) that the optimum particle diameter ranges from about 2 micron for very simple separations (a=1.l2) carried out at an inlet pressure of 6000 p.s.i. to about 40 micron for difficult separations (ot= 1.01 ) carried out at an inlet pressure of only 2000 p s.i Furthermore, the curves shown in figure (1) appear to be in conflict with popular opinion, in that, the more difficult separations are best achieved with particles of relatively large diameter, whereas, simple separations require particles of small diameter for optimum performance. This apparent paradox will be discussed more fully later in the chapter. Equation (18) also discloses some interesting properties of the optimized column. 

Particle Diameter Range 5-100 micron Column length Is less than 150cm Column Aspect Ratio L/R must be greater than unity The Analysis Time must lie between 1 minute and 1 hour... 

Land Subsurface Burst. Everything which was said above about land surface burst applies exactly to the aerial cloud particle population produced by a land subsurface burst in which an aboveground fireball appears. However, a third component of the particle population is found. This component appears to result from soil material which interacted with the fireball at high temperature but which was separated from the fireball early, before the temperature had fallen below the melting point of the soil materials. The particles in this component have diameters ranging from tens of microns to several centimeters and have densities which are apt to be quite low compared with those of the original soil components. The relative abundance of radionuclides in this component is quite constant from sample to sample and is independent of particle size. If we indicate by subscript 1 this third component and by 2,3 the aerial cloud components, radionuclide partitioning can be described by a series of equations of the forms... 

Tower Burst. If the energy of the detonation is sufficient to vaporize the entire tower mass, the particle population is like that described for the land surface burst. If, however, the entire tower is not vaporized, the particle population will consist of three identifiable components— the crystalline and glass components of the surface detonation plus a metal sphere population which arises from melted (not vaporized) tower materials resolidifying as spheres. Such spheres are metallic rather than metal oxide and exhibit the density and magnetic properties of the tower material. The size range of the spherical component is from a few microns to perhaps a few hundred microns diameter. If we indicate by... 

Commercial fluid cracking catalysts are predominantly particles with diameters ranging from 20 to 100 microns and densities of the order of 1.0 to 1.6 g./cc. (based on geometric volume of particles including pores). Gas velocities of 1 to 2.5 ft./second are ordinarily used in the reaction vessels of fluid cracking units. Within this range, the bulk density of the dense-phase fluidized bed is typically 40 to 60% of the bulk density of the packed static bed. 

The foam elements in syntactic foams may be glass microspheres, with diameters ranging from 20 to 200 microns, or other spheres with diameters ranging from 0.05 mm to 2 cm, which are classed as macro-spheres. The materials used to form the spherical particles are glass, phenolic resins, silica, and naturally occurring materials such as perlite and coal dust. The most commonly used materials are glass and phenolic spheres. The syntactic foams are made by simply mixing the micro- or macrospheres into the catalyzed resin until the desired consistency is... 

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