Metals mechanical behavior

By employing anionic techniques, alkyl methacrylate containing block copolymer systems have been synthesized with controlled compositions, predictable molecular weights and narrow molecular weight distributions. Subsequent hydrolysis of the ester functionality to the metal carboxylate or carboxylic acid can be achieved either by potassium superoxide or the acid catalyzed hydrolysis of t-butyl methacrylate blocks. The presence of acid and ion groups has a profound effect on the solution and bulk mechanical behavior of the derived systems. The synthesis and characterization of various substituted styrene and all-acrylic block copolymer precursors with alkyl methacrylates will be discussed. 

M. Stoica, J. Eckert, S. Roth, Z. F. Zhang, L. Schultz, and W. H. Wang, Mechanical Behavior of Fe65 5Cr4Mo4Ga4Pi2C5B5 5 Bulk Metallic Glass, Intermetallics, 13, 764 (2005). 

K.S. Kumar, H. Van Swygenhoven, S. Suresh, Mechanical behavior of nanocrystalline metals and aHoys Acta Mater. 51 (2003) 5743-5774. 

The factors controlling the mechanical behavior of polymer-coupling agent-metal oxide systems have been discussed in terms of the weakest link in a chain concept. Determination of the locus of failure and thus the weak link is not usually reliable by visual inspection, and surface roughness can cause misleading spectroscopic results if failure is near an interface. 

Petrie, S. E. B. in Polymeric Materials Relationships between Structure and Mechanical Behavior , ed. Baer, E. and Radcliffe, S. V., pp. 55-118, American Society for Metals, Ohio Metals Park, 1975... 

The nature of the current density dependence of particle codeposition is the most disputed aspect in the mechanism of composite plating (Section IV). In the simplest case the particle deposition rate is not affected by the current density, either because of particle mass transfer limitations or a current density independent particle-electrode interaction. Since the metal deposition rate increases with current density, this results in a continuously decreasing particle composite content. In other cases the particle-electrode interaction has to be current density dependent. An unambiguous explanation for this dependence has not yet been found, but it is apparent that the metal deposition behavior is involved. 

Despite these successes, important process parameters, like bath agitation, bath constituents and particle type are disregarded. The constants k, 0 and B inherently account for these constants, but they have to be determined separately for every set of process parameters. Moreover, the postulated current density dependence of the particle deposition rate, that is Eq. (2), is not correct. A peak in the current density against the particle composite content curve, as often observed (Section III.3.H), can not be described. The fact that the peak is often accompanied by a kink in the polarization curve indicates that also the metal deposition behavior can not be accounted for by the Tafel equation (Eq. 4). Likewise, the (1-0 term in this equation signifies a polarization of the metal deposition reaction, whereas frequently the opposite is observed (Section 111.3,(0 It can be concluded that Guglielmi s mechanism... 

The conductivity is a solid-state phenomenon, and, as pointed out already, conductivity is not a single chain phenomenon. The band-gap description of a conjugated chain is a one-dimensional model. Additionally, considerably interchain charge transport is necessary to describe a metal-like behavior in the highly doped three-dimensional sample and further transfer mechanisms across the polymer chains have to be discussed. What one actually needs to know in explaining conductivity of organic polymers is how the charge transport proceeds... 

Argon, A. S. in Polsoneric Materials, Relationship Between Structure and Mechanical Behavior , 411, Metals Park, Ohio, ASM, 1975... 

Tungsten metal and tungsten alloy wires have attracted interest for fiber reinforcement of high-temperature materials, in particular of superalloys. However, until now, they have remained exotic materials with only a few specific applications or for model studies of mechanical behavior and are not produced on a large scale. This is at least partially due to the difficulties encountered during composite fabrication and the resulting high cost of the material. 

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