Mechanical dispersoid

Mechanical dispersoid — particulates of solid or liquid matter formed and dispersed into the air by mechanical means, such as grinding, crushing, drilling, blasting and spraying. 

Dust — a dust dispersed phase is a solid mechanical dispersoid ranging in size from submicroscopic to visible. 

Once the precipitates grow beyond a critical size they lose coherency and then, in order for deformation to continue, dislocations must avoid the particles by a process known as Orowan bowing(23). This mechanism appHes also to alloys strengthened by inert dispersoids. In this case a dislocation bends between adjacent particles until the loop becomes unstable, at which point it is released for further plastic deformation, leaving a portion behind, looped around the particles. The smaller the interparticle spacing, the greater the strengthening. 

Table 13.1 covers general information for different particulates, liquids in gas, typical particles and gas dispersoids, behavior of particles in the human body, charging mechanisms, principles of particle size analysis, methods for particle size analysis, and an estimation of the general collection efficiency of available commercial particle removal equipment. 

The effect of dispersoids on the mechanical properties of metals has already been described in Section 5.1.2.2. In effect, these materials are composites, since the dispersoids are a second phase relative to the primary, metallic matrix. There are, however, many other types of composite materials, as outlined in Section 1.4, including laminates, random-fiber composites, and oriented fiber composites. Since the chemical nature of the matrix and reinforcement phases, as well as the way in which the two are brought together (e.g., random versus oriented), vary tremendously, we shall deal with specific types of composites separately. We will not attempt to deal with all possible matrix-reinforcement combinations, but rather focus on the most common and industrially important composites from a mechanical design point of view. 

In early nanocomposites, hard and strong dispersoids, such as SiC, Si3N4, TiC, etc., were mainly incorporated into the matrix to improve the mechanical properties. But in later years, enhancement of fracture strength was also achieved by addition of even soft and weak dispersoids like metals, graphite and h-BN [3-5], The density, microstructure and mechanical properties of nano-sized particulate dispersion nanocomposites were strongly dependent on the volume fraction of particulate dispersion and sintering conditions. 

The super-fine dispersoids with laminar structure and a low modulus could be expected to play a crucial role in improving the machinability of ceramics and their mechanical properties. Among the various nanocomposites, h-BN reinforced composites showed excellent corrosion resistance to molten metal... 

Following these considerations the Al3Zr intermetallic compounds are used as dispersoids or precipitates in the Al-Al3Zr composite system, rather than the monolithic ones [7, 8], Many previous works have been concentrated on the microstructural stability, mechanical properties and thermomechanical processing of these kind of systems. Some authors have studied the hot formability of the same alloy by demonstrating the microstructural stability of Zr-stabilized aluminum alloy from 300 and 500 °C [7],... 

A mode of mechanical alloying is reaction milling, developed for dispersion strengthened aluminum production [1], To produce aluminum dispersoid the aluminum powder is intensively dry milled with carbon powder. The transformed dispersed phase A14C3 is than produced by a chemical reaction, which starts during milling, and it is completed at the next heat treatment process. The resulting powder mixture is then pressed,... 

Mechanical properties and microstructure of dispersoid are influenced by the technology applied. With the near-constant dispersed particle grain size, the influence on strength and plasticity corresponds to the subgrain size and the... 

The structure and physical properties of the thermoplastic vulcanizates (TPE-V) produced in the process of the reactive processing of pol5rpropyl-ene (PP) and ethylene-octene elastomer (EOE) in the form of alloy, using the cross-linking system was analyzed. With the DMTA, SEM and DSC it has been demonstrated that the d5mamically produced vulcanizates constitute a typical dispersoid, where semicrystal PP produces a continuous phase, and the dispersed phase consists of molecules of the cross-linked ethylene-octene elastomer, which play a role of a modifier of the properties and a stabilizer of the two-phase structure. It has been found that the mechanical as well as the thermal properties depend on the content of the elastomer in the blends, exposed to mechanical strain and temperature. The best results have been achieved for grafted/cross-linked blends with the contents of iPP/EOE-55/45%. 

Atto-engineering for more than a whole century is in permanent and almost infinite development. Theoretical background is related to the surface physics and chemistry, quantum and wave mechanics, and quantum electrodynamics. Discrete and constrained discrete models are convenient for describing related events. Tools and equipment are nano- and atto-dispersions and beams (demons, ions, phonons, infons, photons, electrons), ultra-thin films and membranes, fullerenes and bucky tubules, Langmuir-Blodgett systems, molecular machines, nano-electronic devices, and various beam generators. Output is, generally, demonstrated as finely dispersed particles (plasma, fluosol-fog, fluosol-smoke, foam, emulsion, suspension, metal, vesicle, dispersoid). 

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