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The basic conduction profile of the varistors results from semiconductor junctions at the grain boundary of zinc oxide grains.
The grains are with random shape, grain size increased with Tsin and width of the grain size distribution is wide.
Silicon and aluminum are more concentrated at the grain boundary and decreased in the centre.
Comparison between the gray and white grains showed that SiO2 considerably increased and homogenously distributed in the gray grain on the account of ZnO, which indicates that the gray phase is zinc silicate.
Considering the high melting temperature of ZnO, increasing Tsin, Fig. 3, provides the chance for maturation of ZnO phase and enlarging the size of the grains, see Fig. 2, this leads to decrease Eo as a result of decreasing the number of micro barriers between ZnO grains [4], as seen in Fig.4.

This route develops structures of fine spheroidized cementite particles in a fine-grained ferrite matrix.
Introduction Ultrahigh carbon (UHC) steels, containing 1.0% to 2.1% carbon, can be processed to avoid the usual microstructure that consists of pearlite colonies surrounded by a proeutectoid carbide network located at the prior austenite grain boundaries.
Microstructure after austenitization at 850ºC, a) UHCS-1.3C, b) UHCS-1.5C a b a b The microstructures of Fig. 3a and b shows that the effect of the austenitization is to decrease the number of spheroidized particles and to increase the volume fraction of pearlitic carbides.
Since ferrite grain size may be controlled by the carbide particles that pin up the ferrite grain boundaries, no variation in the ferrite grain size was found.

. = the total number of particles with the size less than/ the total number of particles in the system.
According to the number of the definition of distribution function, the number of particles isin the
(1) Eq. (1): Nt——the total number of particles in the system.
Average grain size is in 50nm~60nm; Fig.1 b) shows Silicon chloride becomes Industrialized samples SiOx after pyrohydrolysis.
Average grain size is 25nm.

The range of process parameter is based on number of experiments.
Find out the characteristics of materials and choose the number process parameter which we already select. 2.
The number of factors and their interfaces. 2.
The number of levels and their interfaces.
Finding Result We can find out in friction stir welding, the grain structure can be divided into several major zone ü Fine equated crystallites in the nugget at the weld center nugget zone ü Highly elongated grain with very small cells retracting and advancing side thermo mechanical affected zone (TMAZ) and ü Slightly elongated coarse grain in the heat affected zone (HAZ) and base metal (BM) The formation of fine, equiaxed grains and uniformly distributed, very fine strengthening occasions happened in the weld region are the reasons for highly tensile properties of friction stir welding joints.

Grain size decreased and density increased compared with pure BST ceramics.
Meanwhile, this method makes the grain size grow too big, and fine grain structure can’t be formed easily, thus causing its weaker dielectric properties[4].
The glass phase can inhibit the grain growth, thus forming fine grain structure.
But there are a large number of pores between the crystal particles.
The grain size is effectively reduced when Dy-B-Si-O glass additive is doped.

This optimum immersion time results in a smooth and conformal deposit with a fine grain size.
The grains are nano-sized and smaller than reported [16-18].
The grains in the tin coating kept growing as the plating continued.
Thus the grains growth could not be the result of displacement reaction between the Cu substrate and Sn2+ ions in the bath.
This optimum immersion time results in a smooth and conformal deposit with a fine grain size.

The electrodeposition process can be used to synthesize a very large number of pure metals, alloys, composites and ceramics in nanometre size.
The electrodeposition can be considered as a distinct form of grain boundary engineering by controlling the grain boundary content (types and quantities of grain boundaries) [3].
The presence of grains in the microstructure develops the interface between grain boundaries.
Consequently, this high volume of disorder arrangement of atoms in the grain boundaries as compared to the grains itself has led to the reduction of particle size and structure compactness [4].
Masumura, Grain boundaries in Nanomaterials in: Y.

Powder metallurgy (PM) technique has been considered to produce magnesium product with consideration of less complex, finer grain and improved mechanical properties.
However, a number of issues can also be arising during the PM process, especially residual porosity which associated with certain process such as compacting and sintering processes [4].
The study revealed modification of deformation behaviour with higher extrusion temperature, associated with dynamic recrystallization at 250°C and grain growth occurrence at 300°C.
At 250°C, the maximum of the basal plane is shifted to 60° orientation and the grains tend to rotate to align the basal plane parallel to the extrusion direction.
The brilliant result associated with grain refinement and the presence of second phase particles developed during the PM processing route.

These elements are thought to change the distribution of liquid copper in the scale, steel grain size, and the toughness of steel grain boundary for the crack propagation [7, 8].
The oxidizing atmosphere is also an influence; water vapour in the atmosphere increases the number of crack on the steel surface [9].
Effect of Nickel to Form Fine Grain Scale Structure.
Addition of nickel has the effect of forming fine grain oxide scale.
These dispersions of different phase in the scale make it fine-grained.

Rare-earth elements with larger ionic radius RE 3+ (i.e. with a smaller atomic number) result in the delayed phase transformation [1-3] and the weaker interfacial bonding [3, 6, 7].
The nanocomposites additionally contain globular nano and submicron sized SiC particles, located intragranularly in the Si3N4 grains or intergranularly between the grains.
The defects such as pores, large grains, agglomerates of SiC grains often connected with a porous area were identified by SEM observations and EDX analysis in both the monolithic Si3N4 and the Si3N4+SiC nanocomposites.
crack deflection at the boundaries of elongated Si3N4 grains).
The interfacial debonding energy is directly influenced by the chemical bonding between the grain boundary phase and the grains as well as by the residual stress on the interface due to thermal expansion mismatch.