Characteristics of Microstructure

The number and identification of phases present, including porosity 

Characteristics of each phase, such as size, shape, and orientation 

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Characteristics of microstructure sintered by spark plasma sintering... 

Moskal G. 2009. Thermal barrier coatings characteristics of microstructure and properties, generation and directions of development of bond. Journal of Achievements in Materials and Manifacturing Engineering 37, 2, 323-331. 

Especially fast reactions benefit from the excellent mass transfer characteristics of microstructured devices. In addition, heat management for highly exothermic reactions is greatly facilitated because of efficient removal of heat produced during the reaction. Selective examples of different gas-liquid reactions that have been studied in the microstructured reactors are listed in Table 7.14. 

Traditional interpretation of SEM-images suggests only obtaining flat (planimetric) characteristics of microstructure, which is determined by planimetric nature of an image. Unfortunately, it is often insufficient since, after all, in actual practice we deal with solid structural characteristics of... 

Bernhard Herzog ° studied the precursor, the composition and the structme of the active phase for Fe304-based ammonia synthesis catalyst, and further studied the phase composition and characteristics of microstructure of its precmsor, in particular, the disappearance of precursor and the generation of active phase dm-ing the whole reduction process with in situ XRD experiment at the same time, the toxicity of the catalyst was also explored. 

In this study, microhardness measurements and EDXA analyses were made in the regions around glass fiber strands embedded in the cement paste to elucidate the effects of curing temperature and mineral admixture on the characteristics of microstructure in the interfacial zone. The reduction in flexural strength and toughness in GRC mortars was also discussed being related to the informations obtained from the microhardness measurements and EDXA analyses. 

Examination of the microstructure of the cavitated surface will commonly disclose evidence of deformation such as twins (Neumann hands) in carbon steel and general cold working in other metals (Case History 12.6). Damage from cavitation can be differentiated from attack by a strong mineral acid, which can produce a similar surface appearance, by observing the highly specific areas of attack characteristic of cavitation. Acid attack is typically general in its extent (Case History 12.6). 

To further characterize the event it is first necessary to identify critical features of the initial configuration that will strongly influence the process. For powder compacts, the most obvious features are the morphological characteristics of the powders, their microstructures, and the porosity of the compact. For solid density samples, the grain structure, grain boundaries, defect level, impurities, and inclusions are critical features. 

Characteristic of the microstructure of PET fibers in their final production form is the occurrence of three types of polymer phases crystalline, mesomorphous, and amorphous. The first phase is the result of crystalline aggregation of PET molecules, the second phase—of mesomorphous or, in other words, paracrys-talline aggregation, the third phase—of amorphous aggregation. The mesomorphous and amorphous phases together form a noncrystalline part of the fiber. 

Pitting caused by the dissolution of non-metallic inclusions can increase the value. Consequently, the microstructures of specimens with a high value must be examined to identify the source of the elevated value. In general, P values below 0-10 are characteristic of unsensitised microstructures, while sensitisation is indicated if P, exceeds 0-4. Single loop tests are sensitive to mild degrees of sensitisation but do not readily distinguish between medium and severely sensitised materials. 

Statistical characteristics of the second type define the microstructure of copolymer chains. The best known characteristics in this category are the fractions P [/k) (probabilities) of sequences Uk involving k monomeric units. The simplest among them are the dyads U2, the complete set of which, for example, for a binary copolymer is composed of four pairs of monomeric units M2M, M2M2. The number of the types of k-ad in chains of m-component copolymers grows exponentially as mk so that with practical purposes in mind it is generally enough to restrict the consideration to sequences Uk] with moderate values of k. Their calculation turns out to be rather useful... 

On the basis of the kinetic characteristics of chain polymerisation reactions, it is possible to predict the final microstructures available by a so-called random process from a simple mixture of two comonomers. Indeed, the global mechanism of copolymerisation can be illustrated as presented in Figure 30. 

As a summary to this chapter focusing on polymer chemistry and microstructure, major characteristics of polymers are reported in Table 9, classified under... 

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