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The fractal relationship of strength and particle size distribution shows that with the increased of fractal dimension, the strength of backfill is decreased, that is to say there is negative correlation, the main cause is that the higher parameter D of the fractal dimension, the higher fine-grained content and more non-uniform of the particle size distribution, especially for the thinner full tailings, if properly increasing the content of slightly crude particles, the strength of backfill will be certainly improved to some extent.
At present, few related literatures and studies for fractal features of sample backfill which from in-situ geological drilling, when a large number of mines in which used backfill mining enter the second step stoping, it will comes to quality inspection of backfill in the future, fractal theory is bound to active this research as an effective method.
Fractal theory introduction French mathematician Mandelbrot first put forward the concept of fractal in the characterization of irregular and fragmented objects, this theory is that in the crushing dispersed particles system which shows the fractal features, there is a relationship between the number of particles N size greater than a (> a) and fractal dimension D, the constant C.
(2) The large number of cracked particulate hard to compute in practice usually, for the dispersion system of all the particle mass M0 and the particle mass M of whose size less than a, particle size and occurrence frequency can be expressed as the following Weibull distribution[12] under the uniform particle density, where v is constant
The fractal relationship of strength and particle size distribution shows that with the increased of fractal dimension, the strength of backfill is decreased, that is to say there is negative correlation, the main cause is that the higher values D is, the higher fine-grained content and more non-uniform of the particle size distribution, especially for the thinner full tailings, if properly increasing the content of slightly crude particles, the strength of backfill will be certainly improved to some extent.

From the generalized model a number of well known yield functions and viscoplastic material models for semi-solid and solid materials can be reproduces.
In direct chill casting processes the dendrites grow preferable normal to the surface leading to a grain boundary covered with liquid, whereas in thixoforming processes the solid skeleton is composed of independent globular grains.
Remarks Using the mathematical structure of the relations (10 - 13) we can reproduce a large number of viscoplastic potentials already used in the literature for the modeling of casting, sintering and thixoforming processes: 1.
For this intended purpose the model must account for different behavior in tension, compression and shear and for the application in transient computer codes it should be computationally effective and the number of model parameters should be as low as possible.
This is characterized by grain rearrangement and the loss of coherency of the dendrite network.

Fracture origins in the specimens with effective volume of 15.9 mm3 tested in four-point bending were surface and volume located technological defects with dimensions from 10 µm to 180 µm, mainly in the form of clusters of pores and large SiC grains.
Mechanical properties of Si3N4 - SiC nanocomposites have been investigated during the last fifteen years by a number of authors using fextural strength methods [5-8].
The Si3N4 - SiC nanocomposite consists of a very fine, homogeneously distributed Si3N4 grains with a low aspect ratio and of globular nano and submicron-sized SiC particles, located intergranularly in the Si3N4 grains.

In the honing process, abrasive grain trajectories are forming on the cylinder a network of fine spiral lines.
In the honing process, abrasive grain trajectories form on the cylinder a network of fine spiral lines.
The trajectories of the abrasive grains, [2] Fig.2.
The elements are: 1- grains of the honing stone; 2- the cylinder; 3- the honing head and 4- the lubricant.
The great number of factors (in parameters) which influence the final rugosity (out parameter) and the complexity of their inter-dependence has lead researchers to contradictory results regarding the control of parameters and their influence on the super-finishing process.

Despite large number of applications and studies on the bonding processes of phosphate and iron, detailed microscopic level investigations on the said processes are hard to find.
As a result, if an apatite grain is totally surrounded by iron phosphate coating, the grain is protected during the subsequent stages of weathering.
Large number of coated apatite grains was observed in the natural environment where apatite and iron-rich minerals co-exist.

Introduction Magnesium alloys have excellent specific strength and stiffness, exceptional dimensional stability, high damping capacity, and high recycle ability [1] .The inherently poor workability of magnesium and several of its alloys is due to the limited number of slip systems associated with the HCP crystal structure.
Fig. 2 a-e also show that the microstructure of the AZ31 magnesium alloy matrix has obvious plastic deformation concentration belt, and the recrystallization grains are small in plastic deformation concentration belt, but external grains are relatively bulky [10].
Grain size can also affect material mechanics performance.
Acknowledgements The authors would like to thank the important science research project of Chongqing for its financial support under contract number CSTC2009AB4005.

Introduction Ti3SiC2 is an important metallic ceramic with a number of excellent properties.
In the present study, we also found a number of Ti3SiC2 bulks with the size of 1-2cm during the MA synthesis from a starting mixture composed of n(Ti) : n(Si) : n(Al) : n(c) = 3 : 1 : 0.2 : 2.
Flake Ti3SiC2 grains and a certain amount of equiaxed TiC grains both existed, consistent with XRD phase analysis.
A large amount of fine flake Ti3SiC2 grains were seen in this organization.

Characterization NaY zeolite morphology obtained by SEM observation; in the X-ray diffraction (Cu target Kα-ray tube voltage 40KV, tube current of 40mA, scanning speed 8 ° / min, scan range 4.5°-70 °) on the determination of the crystalline molecular sieve structure of alumina than SiO2/Al2O3, average size and crystallinity; measured in the infrared spectrometer on the skeleton vibration of zeolite crystals (KBr tablet, wave number range 470-4000 cm-1).
Experiments show that the gel concentration is low, high alkalinity the crystallization products of S1 ratio number smaller the particle size, particle size distribution more uniform.
Table 1 Particle size of different gel No. gel Particle size S1 Na2O : SiO2 : Al2O3 : H2O = 14: 10 : 1 : 840 0.7μm S2 Na2O : SiO2 : Al2O3 : H2O = 18.5: 12.8 : 1 : 975 >1μm Crystallization are often able to influence the length of time the water level and thermal reaction products of the complete grain size.
The prevailing view now is the crystallization of the longer, more thorough hydrothermal; long crystallization time, but the grain will increase.
Synthesis of Microsized NaY Zeolite and Grain Size Distribution Control.

Introduction Since the discovery of high-Tc superconductors in the La-Ba-Cu-O system [1-2], a great number of studies have been performed on the development of new higher Tc superconductors.
The internal friction is determined by the free decay method [9]: N o A A N Q ln 11 = − (1) where N is the number of oscillating cycles, during which the amplitude decreases from Ao to AN.
In figure 2 are presented the micrographs of SEM for the Sm-123 samples, where it can be verified rounded grains characteristics of this material.
The SEM analyses show high grain homogeneity with clean grain boundaries.

It was found [2] that many kinds of metals and alloys pronounced creep damage featured by the grain boundary cavities at low stress levels when the working temperature is between 1/3 and 2/3 times of the material melting temperature.
For 0s dwell time, the alloy fractured surfaces exhibited striations and transgranular cracking, while the fracture surface at 550°C is slightly rough and the number of secondary cracks increased significantly, which indicates more plastic feature.
The introduction of dwell time reduced the strength of material grain boundary greatly and a large number of secondary cracks emerged with trigeminal grain boundaries separating on the fracture, as shown in Fig. 4(c) and (d) .