Revealing the microstructure

Polished and etched sections of composite materials and ceramics are examined by conventional methods of optical microscopic imaging at magnifications up to approximately 1000 1. These methods are described in Section 3.1.1 and illustrated by microstnictural images. Methods of electronic image processing are addressed in Section 3.1.2. Section 3.2 contains tips on contrast enhancement and etching of the polished section. 

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High-resolution and NMR, and recently, multidimensional methods have revealed the microstructures of complex polymers. In particular, multidimensional (2D- and 3D-) NMR have proven to be useful techniques to identify small amounts of irregular structures in synthetic polymers. In this entry, specific topics to be covered include the use of solution NMR methods to study polymer stereochemistry/ tacticity, monomer composition and sequence distribution, short-chain branches, and chain-end structure, as these parameters influence the material s mechanical, thermal, optical, and electrical properties. 

Starting from experimental application of passivity, simple metals were investigated at first. Improved techniques yielded a better understanding of ionic and electronic properties at the interface, at first for single crystals. Now an even better understanding is achieved using microscopic techniques of electrochemistry, which reveal the microstructure of passive films. Advanced techniques of surface preparation allow... 

Figure 9.21 presents SEM pictures of the corrosion layer of plates with PbSnCa grids. The CL has become thinner during curing, thus revealing the microstructure of the grid metal. 

This notion re-emerged as important in a very different context. Look at a well-known printed chemical subject index, and you will note that the number of entries under different headings is very disparate there too. This effect is due to the structure of the subject in question, and to the vocabulary used. It turns out that indexers description of the content of a particular document differs in ways influenced directly by their estimation of the number of postings expected at particular subject headings - and that one might therefore be able to capture decisions made by indexers which would reveal the microstructure of conceptual fields - what today would be called the knowledge structure of the domain. In order to capture these relations it was necessary to compare two entries, and identify variant subject descriptions by first isolating the common parts of the two entries. 

The recipes for preparing the most common etchants used to reveal the microstructure of iron and steel are Hsted in Table 2.4. 

Plasma etching is a quick and effective etching method for revealing the microstructure of ceramics based on silicon nitride (Chatfield 1983 O meara (1986) Taffner 1990). It makes possible a clear representation of grain boundaries, grain boundary... 

Figure 2 contains images that reveal the microstructural differences between the bonded, vibro-cast, and fused-cast AZS refractories. The microstructure of the fusion-cast AZS material is a mixture of corundum and zirconia co-precipitates, isolated zirconia dendrites, and a sodium alumino silicate... 

A major difficulty in plasma and ion etching is that textures, such as steps, cones and holes, can be produced which are artifacts and which do not reveal the microstructure. Of all the methods of specimen preparation, etching is the most prone to such artifacts and thus image interpretation is very difficult. Etching preparations are useful for comparison with structures formed during other specimen preparation processes, especially microtomy. Such complementary studies are essential to the determination of the true polymer structure. 

G SEES triblock polymer in Figure 5.55 [273]. Double staining was used to reveal the microstructure of both the nylon matrix with PTA and the styrene rich regions of the triblock polymer with RUO4. There is selective absorption of PTA by the amorphous nylon phase so it becomes dense and the individual crystalline lamellae are seen as meandering white regions in the matrix. Regions of Kraton up to 200 nm in size are seen to consist of styrene rich (black) cylinders in a matrix [273]. 

The specimens were heated by electrical resistance heating. Prior to treating, the sp>ecimens were soaked in concentrated HCl (2 M) solution for 15 minutes duration with the purpwse to remove the native oxide film that commonly forms on austenitic stainless steel and protects the metal matrix from corrosion. This oxide layer is believed to act as a barrier for diffusional nitrogen transport (Rie, 1996). After thermochemical treatments, the sp>ecimens were quenched in water. The treated sp>ecimen cross sections were first characterized by metallographic examination. To reveal the microstructure, the polished surface was etched... 

To reveal the microstructure of solder alloys and interfaces, a chemical etching mixture of weak-to-strong acid, diluted with isopropanol... 

A solution of nitric acid and alcohol, Nital, is used for etching of metals to reveal the microstructure. ISO 14104 is one of the standards detailing this well known procedure. 

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