Microstructural development

Instead of devoting more space to copolymers, we turn next to stereoregular polymers, in which many of the descriptions of microstructure developed in Sec. 7.6 can also find application. 

Figure 12.3. Comparison between experimental observations (a-c) and simulation predictions (d f) of the microstructural development of a chessboard pattern forming in a Con sPtf,) j alloy slowly cooled from 1023 K to (a) 963 K, (b) 923 K and (e) 873 K. The last of these was maintained at 87.3 K to allow the chessboard pattern time to perfect itself (Le Bouar ei iil. 2000) (courtesy...

H. Li, F. Czerwinski, J. A. Szpunar. Monte-Carlo simulation of texture and microstructure development in nanocrystalhne electrodeposits. Nanostruct Mater 9 673, 1997. 

Dong, J., lin, Y.S., Hu, M.Z.C., Peascoe, R.A., and Payzant, E.A. (2000) Template-removal-associated microstructural development of porous-ceramic-sup-ported MFI zeolite membranes. 

After the Initial thermal pretreatments, conversion Is directly related to the nature of the microstructure developed In aged PILC. In the early stages of collapse of the microstructure. 

Banfield J.F., Welch S.A., Zhang H., Ebert T.T., and Penn R.L. (2000) Aggregation-based crystal growth and microstructure development in natural iron oxyhydroxie biomineralization products. Science 289, 751-754. 

The microstructural development is controlled mainly by the Si3N4 starting powders, the additives and the sintering parameters. 

This chapter aims to describe the principles behind the processing, microstructural development and properties of particulate ceramic composites and to illustrate these using experimental results. The main emphasis is on examples where the addition of particulates to a ceramic matrix causes new mechanisms to operate that give an improvement in properties greater than would be expected from a rule of mixtures . The chapter concentrates almost exclusively on structural composites, since this is where most work has been done to date. Particulate nanocomposites are included in the chapter, since the important examples described are currently at the coarse end of the nanoscale , and the principles underpinning their properties seem to be a simple extension of those relevant to the microcomposites with which the rest of the chapter is concerned. 

The next section describes the processing and microstructural development of particulate composites, and is followed by a section on thermal residual stresses. These stresses are often the most obvious consequence of adding second-phase particles to a matrix and can have a profound effect on properties. Factors determining the toughness, strength and wear resistance of particulate composites are then considered in turn, and the chapter concludes with an assessment of possible future developments in this area. 

Hsueh, C.H., Evans, A.G. and Coble, R.L., Microstructure development during final/intermediate stage sintering -1. Pore/grain boundary separation , Acta. Metall., 1982 30 1269-1279. 

Wotting, G., Kanka, B. and Ziegler, G., (1986), Microstructural development, microstructural characterization and relations to mechanical properties of dense silicon nitride , in Hampshire S, Non-oxide Technical and Engineering Ceramics, London and New York, Elsevier Science, 83-96. 

Hoffmann, M.J. (1994), Analysis of microstructural development and mechanical properties of Si3N4 ceramics , in Hoffmann, M. J. and Petzow, G., Tailoring of Mechanical Properties of Si lN ceramics, NATO AST Series, Series E Applied Science, 276, Dordrecht, Kluwer Academic, 59-71. 

The conceptual breakdown of polymer processing dating back to the first edition of 1979, presented earlier, remains the same. Yet the field and the industry, in the current transition period, have been focusing on and growing through what used to be called compounding, and is now expanded from the simple dispersion and distribution of fillers in polymer melts, to encompass microstructure development and stabilization in... 

D.A. Hughes et al Near surface microstructures developing under large sliding loads. J. Matls. Eng. Perf. 3, 459 175 (1994)... 

Typical microstructures developed by solid state sintering, liquid phase sintering and firing a porcelain are shown in Fig. 5.20. 

Halse and Pratt (H57) reported SEM observations on pastes hydrated at various temperatures. In those hydrated at 8°C or 23 C, the main feature was fibrous material that was considered to be hydrous alumina, but which could also have been partly dehydrated CAH,q. The hydrating grains of cement were surrounded by shells of hydration products, from w hich they tended to become separated in a manner similar to that observed with Portland cement pastes (Section 7.4.2) though the authors recognized that this could have been partly due to dehydration. Two-day-old pastes hydrated at 40"C showed spheroidal particles of CjAH and thin, flaky plates of gibbsite. In pastes mixed with sea water, hydration took place more slowly, but no other effects on microstructural development were observed. 

Depending on conditions during processing and storage, a crystalline microstructure develops in many foods that can significantly impact food propaties. Some important characteristics of the crystalline dispersion include the crystalline phase volume, mean size and size distribution of crystals, shape and surface characteristics of the particles, polymorphic characteristics, and any network structure that forms between... 

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