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Table-top scanning electron microscope (SEM) (Hitachi TM-3000) was utilized to analyze surface morphology of the oven-dried samples and non-contact mode atomic force microscope (AFM) (Nano Navi SPI3800 N) was used to examine the root mean square (RMS) surface roughness and mean grain size of the oven-dried samples.
It can be seen from the root mean square (RMS) surface roughness and mean grain size measurement (Fig. 5), an increasing in RMS surface roughness and decreasing of mean grain size are found from the addition oven-dried samples which have more SiO2 NPs.
Moreover, a large number of experiments have found that a higher RMS surface roughness of the dielectric layer is directly increasing the leakage current of the samples [12, 13].
Fig. 4 SEM micrographs for oven dried natural Aloe vera pastes with different wt% loading of SiO2 NPs (a) 0.5 wt%, (b) 1.0 wt%, (c) 1.5 wt%, (d) 2.0 wt%, (e) 2.4 wt%, (f) 3.8 wt% Fig. 5 RMS roughness and mean grain size comparison for oven dried samples with different wt% loading of SiO2 NPs Conclusion In this work, dielectric properties of natural Aloe vera paste loaded with different weight percent of SiO2 NPs as filler had been investigated.

Factors that affect the surface roughness of grinding.As the formation process of surface roughness when machining, grinding surface roughness is also formed by the geometrical factors and the plastic deformation of the surface metal .The main factors influencing the grinding surface roughness are: the particle size of grinding wheel, the hardness of grinding wheel, grinding wheel dressing grinding speed, number of grinding workpiece circular grinding radial feeding and light week to speed and axial feeding liquid cooling and lubrication.
In the process of machining, plastic deformation resulting from cutting force, making the lattice distortion, distortion, intergranular shear sliding, grain being stretched and fibrosis, or even broken, these will increase the hardness and strength of surface layer of metal, this phenomenon is called cold work hardening (or improved).The result of the surface layer of metal reinforcement, increasing the metal deformation resistance, reduce the plastic metal, metal changes the physical properties of it .Metal  which is of cold work hardening lying in a high-energy unstable state, as soon as possible, the instability of the metal is to transform to relatively stable state, this phenomenon is called weakening.
Work piece materials should have appropriate metallographic organization (including state, grain size and size distribution).
Choose smaller radial feeding, choose the larger wheel speed and smaller axial feeding speed, work piece speed should be lower, adopting fine-grained grinding wheel; fining napping grinding wheel working surface, making the grinding grain on grinding wheel sharp, also can achieve good grinding effect.

The dislocation cannot be fully offset by dynamic recovery and dynamic recrystallization, a large number of dislocations still existed, so the flow stress were higher with the increasing of strain rate.
The discontinuous yielding phenomenon caused by a large amout of movable dislocations at grain boundaries.
A large amout of dislocations accumulate at grain boundary when deformation amount increasing, the movement of the grain boundary is hindered, leading to an increasing of stress.
Dynamic recovery occurred, when the dislocation density at the grain boundary reached certain critical value, the flow stress decreased.

An increasing diffusion coefficient with increasing nitrogen content was reported in Pd alloys, which possess the same bcc structure that the Nb1Zr alloy, in which nitrogen atoms fills trapping sites, which are a consequence of the high density of grain boundaries or dislocations [20].
The Nb1Zr alloys studied here are polycrystalline with small grains and contain a large number of grain boundaries, which can form trapping sites for nitrogen atoms and as a consequence, increase the nitrogen diffusion coefficient.
This increasing in the diffusion coefficient was attributed to the fact that nitrogen atoms fill trapping sites, which are a consequence of the high density of grain boundaries present in the sample.

Introduction In recent years, nanostructured materials (single- or multiphase polycrystals with grain or domain sizes in the nanometer range, typically less than 100 nm at least in one dimension) have been attracting much attention due to their scientific and engineering significance [1-3].
In particular, substantial increase in strength, along with good ductility, has been observed in a number of alloys with multiphase nanoscale microstructures [4].
This indicates grain growth of the fcc particles, which nevertheless are still in the nanometer regime (below 100 nm).
(a) XRD patterns (Co Kα radiation) of as-milled Zr57Ti8Nb2.5Cu13.9Ni11.1Al7.5 powder and after heating up to the completion of the first DSC exothermic event, revealing grain growth of the fcc-Ti2Nitype phase upon heating and (b) DSC scan (heating rate 40 K/min) for the MA Zr57Ti8Nb2.5Cu13.9Ni11.1Al7.5 glassy powder.
Schultz, in: Grain Size and Mechanical Properties - Fundamentals and Applications, Edited by M.

Due to its high density (~9.4g/cm3) and high Z-number of Lu, Lu2O3 can serve as a promising host material for some novel applications, like digital radiography.
It appeared promising for phosphor synthesis because of its success in controlling fine grain size, multicomponent crystalline with high homogeneity at considerably lower temperatures and with reduced processing time.
Table 1 Particle size calculated from Scherrer,s equation and specific surface area of the resultant powder Sample 1.7 (S1) 1.3 (S2) 1.0 (S3) Grain size from Scherrer,s equation(nm) Specific surface area (m2g -1) 115 8.5 86 13.9 35 21.5 The average particle size of S1, S2 and S3 is 115nm, 86nm and 35nm, respectively.
The product does not possess a well-defined grain boundary and size, due to the spontaneous reaction between the oxidizer and fuels.
The grains are equiaxed and their diameters are in the range of ~ 80-90nm, which reasonably accords with what was revealed by Scherrer ,s formula.

Reduction of the grain size in the ingot can be achieved by adding AlTiB ligatures to the alloy, but this leads to higher prices of final products.
There is another technique for producing a fine-grained structure: creating an intense flow of the melt at the phase boundary during the crystallization process.
Forced melt flow at the phase boundary at the moment of the crystallization facilitates the destruction of dendritic formations, which leads to the emergence of new areas of crystallization and thus ensures the formation of a fine-grained and homogenized structure in the ingot.
a) b) Fig. 2 Rotary casting machine with electromagnetic modifier a) modifier location; b) cross section of the mold, where: 1 - copper mould; 2 - solid phase of the ingot; 3 - liquid phase of the ingot;4 - steel strip; 5 - inductor of modifier From the viewpoint of electrical engineering a number of difficulties arise with the development of the EM-modifier to affect the ingot liquid phase.
a) b) c) Fig. 4 Ingots macrostructure: a) ingot cast on the industrial unit; b) ingot cast on the laboratory facilities without electromagnetic impact; c) ingot cast on a laboratory facilities with electromagnetic impact The best grain refinement has been achieved at simultaneous air cooling of the top ingot surface and electromagnetic effects (Fig. 4c).

Results and discussion SEM was used to analyze the morphological features of the samples, Fig 1 show continuous film with large grains was formed from aggregation of small CZTS nanoparticles.
But with presents some roughness.To obtain high efficiency solar cell, High-temperature treatment is indispensable to increase the crystallinity and grain size of CZTS films, because the efficiency of polycrystalline solar cell increases with an increase in grain size of the adsorbed layer [4] .The surface morphology of thin films will change depending with different stack sequence in precursors [5].
The AFM images showed more elongated particles and show the smooth, uniform, homogeneous and densely packed grains.
Acknowledgements This work was supported by the Nano-optoelectronics Research Laboratory, School of Physics: UniversitiSains Malaysia under grant number 203/PSF-6721001 and TWAS.

Fine-grained martensite present with slightly shaped grain boundaries.
These limits are the same boundaries of former austenite grains.
Note the limits of the former austenitic grains and martensite fine bands (Fig. 3a) of width between 0.5 - 1μm.
Acknowledgments This work was partial supported by project number CEEX-C297/2006.

In this model the grain contains a SiC core surrounded by a graphite layer, the latter being permeable for SiC vapor.
The described model is based on spherical SiC grains with a large surface compared to the volume and mass.
In summary we have presented a model for the evolution of the SiC source material based on sphere like grains surrounded by a graphite shell.
As a reasonable explanation the difference in the SiC grain surface of the sphere like modelling assumption and experimentally found needle like structure was named.
Acknowledgements This work was supported by the Deutsche Forschungsgemeinschaft (DFG) under contract number We2107/2-3 and We2107/3-1 (For 476-1).