Vapor—liquid—solid process

The directions of the mass and energy fluxes between the phases cannot be predicted because of the influence of convection in axial column direction, and due to the fact that multicomponent mass-transport phenomena may result in uphill transport [30]. There are three types of transport resistances present in the considered three-phase (vapor/liquid/solid) process... 

The Vapor-Liquid-Solid Process In the VLS process silicon and carbon-rich vapors (usually CH4, SiO, or SiC ) react at 1400°C to from SiC on a liquid... 

Versailles Agreement on Materials and Standards vapor phase formation and condensation process valence electron concentration vapor-liquid-solid process vapor-solid reaction wurtzitic boron nitride... 

Vapor-Liquid-Solid Process In the VLS process, silicon- and carbon-rich vapors (usually CH4, SiO, or SiCU) react at 1400 °C to SiC on a liquid alloy [Eq. (9)]. Microscopic particles of an alloy are first distributed on a substrate (graphite) and then exposed to silicon- and carbon-rich vapors. The presence of a liquid catalyst, such as a transition metal or usually an iron alloy, distinguishes this method from all other whisker preparation methods. 

By the vapor-liquid-solid process using an iron catalystl l... 

The most important nanomaterial synthesis methods include nanolithography techniques, template-directed syntheses, vapor-phase methods, vapor-liquid-solid (VLS) methods, solution-liquid-solid (SLS) approaches, sol-gel processes, micelle, vapor deposition, solvothermal methods, and pyrolysis methods [1, 2]. For many of these procedures, the control of size and shape, the flexibility in the materials that can be synthesized, and the potential for scaling up, are the main limitations. In general, the understanding of the growth mechanism of any as-... 

The first major hazard in process plant is fire, which is usually regarded as having a disaster potential lower than both explosion and toxic release2. However, fire is still a major hazard and can under the worst conditions approach explosion in its disaster potential. Fire requires a combustible material (gas or vapor, liquid, solid, solid in the form of a dust dispersed in a gas), an oxidant (usually oxygen in air) and usually, but not always, a source of ignition. Consider now the important factors in assessing fire as a hazard. 

It is evident from the title of this symposium that as a result of recent requirements to reduce pollutant levels in process wastewater streams, improved techniques for predicting the vapor-liquid-solid equilibria of multicomponent aqueous solutions of strong and/or weak electrolytes are needed. In addition to the thermodynamic models necessary for such predictions, tools have to be developed so that the engineer or scientist can use these thermodynamic models correctly and with relative ease. 

Almost defect-free GaSb whiskers are formed by the so-called VLS process vapor-liquid-solid) that was introduced by Ellis and Wagner [32]. Initially formed Ga droplets on the substrate, formed by pyrolysis of t-BusGa which is present in the gas phase to some extent due to the dissociation of the starting t-BusGa - SbRs adduct, catalyze the decomposition of t-BusGa and SbRs and... 

In all of these processes it is possible to increase the yield of whiskers by adding metallic impurities, and the sublimation process requires such additions. The vapor—liquid—solid (VLS) growth mechanism is often thought to be involved. 

An extensive process data base has been accumulated which includes (1) vapor-liquid-solid equilibrium data for binary... 

Because ASPEN is to be used with coal conversion processes, its streams can be designated to carry an arbitrary number of solids or solid phases. This is done by specifying any number of substreams. In fact, the conventional vapor/liquid stream is normally assumed as a substream and solids can comprise other substreams. For the conventional vapor/liquid substream, process data is carried on component molar flows, total molar flow, temperature pressure, specific enthalpy, specific entropy, density, molar vapor fraction, molar liquid fraction, and molecular weight. For solid substreams, which are called "non-conventional substreams," the characterizing data is not as deterministic. The information associated with these substreams is called "attributes". Such attributes may be particle size distribution, ultimate and proximate analyses, or other material specific information. Another type of substream is an "informa-... 

For example, when we consider the design of specialty chemical, polymer, biological, electronic materials, etc. processes, the separation units are usually described by transport-limited models, rather than the thermodynamically limited models encountered in petrochemical processes (flash drums, plate distillations, plate absorbers, extractions, etc.). Thus, from a design perspective, we need to estimate vapor-liquid-solid equilibria, as well as transport coefficients. Similarly, we need to estimate reaction kinetic models for all kinds of reactors, for example, chemical, polymer, biological, and electronic materials reactors, as well as crystallization kinetics, based on the molecular structures of the components present. Furthermore, it will be necessary to estimate constitutive equations for the complex materials we will encounter in new processes. 

A vapor-liquid-solid (VLS) technique (Petrovic et al, 1985 Milewski et al, 1985) can be used to grow exceptionally strong and stiff silicon carbide whiskers. The name VLS comes from the fact that the process uses vapor feed gases, a liquid catalyst, and solid crystalline whiskers are the end product. Figure... 

For their rich potential in various applications described in the previous section, the synthesis and assembly of various ZnO micro and nanostructures have been extensively explored using both gas-phase and solution-based approaches. The most commonly used gas-phase growth approaches for synthesizing ZnO structures at the nanometer and micrometer scale include physical vapor deposition (40, 41), pulsed laser deposition (42), chemical vapor deposition (43), metal-organic chemical vapor deposition (44), vapor-liquid-solid epitaxial mechanisms (24, 28, 29, 45), and epitaxial electrodeposition (46). In solution-based synthesis approaches, growth methods such as hydrothermal decomposition processes (47, 48) and homogeneous precipitation of ZnO in aqueous solutions (49-51) were pursued. 

Vapor phase growth is commonly used to produce nanowires. Starting with the simple evaporation technique in an appropriate atmosphere to produce elemental or oxide nanowires, vapor-liquid-solid, vapor-solid and other processes are made use of. 

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