Solid materials, properties

In the present paper, the approach chosen at our institute to study the phenomenon of attrition is briefly presented. In the results section, the link between bulk solids material properties and attrition results is discussed. The findings document the suitability of our approach for identifying material specific attrition mechanisms. 

Theuns, E., Merci, B., Vierendeels, J., and Vandevelde, P. Influence of solid material properties on numerical large scale flame spread calculations. Interflam, Edinburgh, U.K., 2004, pp. 1245-1256. 

Thus, thermal conductivity is predicted proportional to the square of velocity. The factor Asoiid is controlled only by the solid material properties (minerals). Table 9.16 shows some values for selected minerals. Quartz has a distinctly high magnitude within the most abundant rock-forming minerals, attributed to its high thermal conductivity. Therefore, as tendency for igneous... 

Solid Material Property Granite Basalt Limestone Dolomite... 

This chapter is organized as follows. The numerical model is firstly presented, followed by an assessment of characteristic time scales which are relevant for the adopted quasisteady approach. The impact of pressure, solid material properties, equivalence ratio, inlet velocity, surface radiation heat transfer, and gas-phase chemistry on the transient microreactor response is then elaborated. Based on the outcome of the previous computations, implications for the design of microreactor systems are outlined. 

The start-up of methane-fueled, catalytic, channel-flow microreactors has been investigated numerically with a transient code that included full elliptic flow description, detailed hetero-Zhomogeneous chemistry, and all relevant heat transfer mechanisms in the reactor. Of particular interest were operating conditions pertinent to microturbine-based microreactor systems. Parametric studies have been carried out to identify the effect of various operations parameters, such a pressure, equivalence ratio, solid material properties and radiation properties on the transient process leading to ignition and finally to steady state operation. The following are the key conclusions of this smdy. 

The model gives reasonable results for each case in which both material and thermal flow parameters are changed. Influences of many physical parameters of the SOFC are extracted from the current-voltage curve and can be investigated separately. The model is based on a combination of electric laws, gas flow relationships, solid material properties and electrochemistry correlations and is characterized by as low a number of requisite factors as possible. During calculations, the advanced model is very stable and can be used for both simulations and optimization procedures. In contrast, the classic model is very sensitive to input parameters and very often generates nonphysical results (e.g. for i = OA/cm ). 

Work on EXAFS then progressed very little until the advent of the synchrotron radiation source (storage ring), described in Section 8.1.1.1. This type of source produces X-ray radiation of the order of 10 to 10 times as intense as that of a conventional source and is continuously tunable. These properties led to the establishment of EXAFS as an important structural tool for solid materials. 

Figure 1.1 shows a typical stress-volume relation for a solid which remains in a single structural phase, along with a depiction of idealized wave profiles for the solid loaded with different peak pressures. The first-order picture is one in which the characteristic response of solids depends qualitatively upon the material properties relative to the level of loading. Inertial properties determine the sample response unlike static high pressure, the experimenter does not have independent control of stresses within the sample. 

Investigations in the field of shoek eompression of solid materials were originally performed for military purposes. Speeimens sueh as armor were subjected to either projectile impact or explosive detonation, and the severity and character of the resulting damage constituted the experimental data (see, e.g., Helie, 1840). Investigations of this type continue today, and although they certainly have their place, they are now considered more as engineering experiments than scientific research, inasmuch as they do little to illuminate the basic physics and material properties which determine the results of shock-compression events. 

See 2-3.1. Electrical conduction through solids takes place both through the bulk material and over the surface. In most cases surfaces have different physical and chemical properties than the bulk, for example due to contamination or moisture. Volume and surface resistivity can be separately measured for solid materials such as antistatic plastic sheet. Powders represent a special case since although both surface and bulk conduction occur, their contributions cannot be individually measured and the volume or bulk resistivity of a powder includes surface effects. 

Charcoal Tubes Reference has been made earlier to adsorption, which is the property of some solid materials, such as activated charcoal, to physically retain solvent vapors on their surfaces. In environmental health testing, the adsorbed vapors are removed, generally with a solvent, in a laboratory. The solvent is then analyzed by physical methods (gas chromatography, etc.) to determine the individual compounds whose vapors, such as benzene, were present in the sampled air. Industrial atmospheric samples can be collected in small glass tubes (4 mm ID) packed with two sections of activated charcoal, separated and retained with fiberglass plugs. To obtain an air sample, the sealed ends of the tube are broken off, and air is drawn through the charcoal at the rate of 1 liter per minute by means... 

Instruments based on the contact principle can further be divided into two classes mechanical thermometers and electrical thermometers. Mechanical thermometers are based on the thermal expansion of a gas, a liquid, or a solid material. They are simple, robust, and do not normally require power to operate. Electrical resistance thermometers utilize the connection between the electrical resistance and the sensor temperature. Thermocouples are based on the phenomenon, where a temperature-dependent voltage is created in a circuit of two different metals. Semiconductor thermometers have a diode or transistor probe, or a more advanced integrated circuit, where the voltage of the semiconductor junctions is temperature dependent. All electrical meters are easy to incorporate with modern data acquisition systems. A summary of contact thermometer properties is shown in Table 12.3. 

In many cases, less intense pressure or stress waves are encountered in which times to achieve peak pressure may be hundreds of nanoseconds or more. The study of solids under these conditions can be the source of mechanical, physical, and chemical properties of solid materials at large strain, high pressure, and high strain rates. 

In shock-compression science the scientific interest is not so much in the study of waves themselves but in the use of the waves as a means to probe solid materials. As inertial responses to the loading, the waves contain detailed information describing the mechanical, physical, and chemical properties and processes in the unusual states encountered. Physical and chemical changes may be probed further with optical, electrical, or magnetic measurements, but the behaviors are intimately intertwined with the mechanical aspects of the waves. 

The fluid mechanics origins of shock-compression science are reflected in the early literature, which builds upon fluid mechanics concepts and is more concerned with basic issues of wave propagation than solid state materials properties. Indeed, mechanical wave measurements, upon which much of shock-compression science is built, give no direct information on defects. This fluids bias has led to a situation in which there appears to be no published terse description of shock-compressed solids comparable to Kormer s for the perfect lattice. Davison and Graham described the situation as an elastic fluid approximation. A description of shock-compressed solids in terms of the benign shock paradigm might perhaps be stated as ... 

The shock-compression pulse carries a solid into a state of homogeneous, isotropic compression whose properties can be described in terms of perfect-crystal lattices in thermodynamic equilibrium. Influences of anisotropic stress on solid materials behaviors can be treated as a perturbation to the isotropic equilibrium state. ... 

The contrast in knowledge is a result of the degree of complexity of materials properties elastic piezoelectric solids have perhaps the least complex behaviors, whereas ferroelectric solids have perhaps the most complex mechanical and electrical behaviors of any solid under shock compression. This complexity is further compounded by the strong coupling between electrical and mechanical states. Unfortunately, much of the work studying ferroelectrics appears to have underestimated the difficulty, and it has not been possible to carry out careful, long range, systematic efforts required to develop an improved picture. 

In the following we review very briefly applications of VASP to alloys and inter-metallic compounds illustrating the potential in making ab-initio predictions of materials properties, in characterizing solid surfaces, and in studying the structure and properties of complex melts. For a more extensive list of applications, see Refs. [10, 17]. 

These are Osually mineral oils of medium or low viscosity, which contain specific coirrorion inhibitors arid.anti-Qxidants In spite of the relatively low protective properties of the fluid films, which are not nearly so great as those, Of the previouriy described solid films, these materials have an established field of useon the internal surfaces of tririks and assembled mechanisms, and where solid material or solvent cannot be tolerated. ... 

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