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Introduction The unique combination of properties of boron carbide (B4C) and the difficulties to obtain dense bodies using pressureless sintering, which is the simplest and the cheapest technology of powder metallurgy, are the reasons that the prevailing number of articles devoted to B4C to start with description its high mechanical properties, chemical stability, neutron-absorbing properties and with the problems to consolidate that compound.
Due to the bad plasticity of B4C, low values of self-diffusion coefficients of B and C and high resistance to grain boundary sliding, near theoretically dense B4C can be produced by the method of hot pressing (HP) at temperatures higher than 2300oC [1].
To activate the densification of B4C we use high-temperature solid state replacement reactions which could be demonstrated by React.1: B4C + MeIV-VIC → MeIV-VI B + C (1) Transition metal carbides used as additives during pressureless sintering of boron carbide have a number of advantages as compared with the corresponding metal oxides or other additives used for the same purpose [3].
Among the boron carbide grains there are secondary obtained B4C-W2B5 grains.
The presence of second metal boride phase around grains of B4C impedes crack propagation thus improving fracture toughness of the sintered body.

When the sliding was about 300m, furrows were observed on the friction surface, which indicated that the wear mechanism was grain-abrasion, Fig. 4 b).
Both furrows and flaking were found in Fig.4 c) and d), which indicated the wear mechanisms were abrasion and grain-abrasion.
In the initiative stage of friction, the wear mechanism was mainly grain-abrasion.
While when the friction layer was formed, the wear mechanism was a combination of grain-abrasion and abrasion.
Acknowledgements The study was financially supported by the Research Award Fund for Outstanding Young Scientists, Shandong, China (BS2009CL027);National Science Funding Program (number 51072085); Qingdao Science and Technology Program (number 10-1-1-8-gx).

Introduction Wireless sensor network consists of a number of random distributed tiny nodes in a self-organizing way.
Currently, In granary monitoring, wireless sensor network which deployed in grain storage, does the food temperature and humidity acquisition.
This is because the data suddenly increases with the number of the nodes increased.
The gateway system has been deployed in grain depot to monitor and manage grain reserves.
It turns out to be reliable, and realizes remote grain temperature monitoring.

But there is not similar model to state the mixing law of magnetic medium and especially not enough research for hybrid effect of magnetic and dielectric medium. 1 Existing electromagnetic parameters of the model and formula Assume an inhomogeneous medium which is composed of N grains and the intensity of each is b, and b«λ (λ is the wavelength of the incident wave), the distance from respective grain to the center is r1, r2……rk,among them the dielectric function of number i isεi; each crystal distribution function is P（ε1, ε2……εn）, and it is equal to the polarization function of each crystal P（ε1）×P（ε2）×……×P（εn）. the electric field strength and electric induction strength of number i are estimated by dielectric function and electric field intensity of all the samples of crystal which is implanted in homogeneous medium grain.
If the shape of the grain is as sphere , and it’s size is small, the formula (1) can be approximate to: （2） Type qi is the volume fraction of ith ;in the formula (2), assumeεe=ε0 and get the effective dielectric function: （3） For composites constituted of two kinds of components (1 and 2),the volume fraction of 1, Less component materials is q; and 2, the more is (1 - q) .Assumeεe=ε2, by the formula (2) we can get: （4） Formula (4) is the effective dielectric function.

Polarity of formic acid is stronger than alcohol, which can form hydrogen bonds strong secondary placement, including hydrogen bonds with other polar molecules.Silk fibroin protein consists of a large number of hydrophobic amino acid and a small amount of close water amino acid.Therefore, hydrophobic amino acids is easy to accumulate together.In formic acid, the increase of complexity and size of the residual groups outside of the carboxyl group reducing the polarity of formic acid and the crystallographic ability of fibroin protein.Therefore, Silk solution of fibroin formic acid is not only stable and but also no precipitation after a long time.
XRD spectrum of sf treatmented by different concentrations 88% formic acid when the concentration is 15% Fig. 4. shows when the concentration is 15%, peak strength and width of βcrystal of SF in formic acid with a 98% concentration is bigger that tn formic acid with a 88%.Under the same condition ,crystallization role of formic acid with a 98% concentration is better than formic acid with a 88% concentration . 4.3 Diameter of grain Table 2 Grain diameter of silk trenmented by different formic acid Concentration of formic acid Concentration of Sf solution（Quality ratio） Diameter of grain（nm） 88% 5% 11.08 10% 9.785 15% 9.459 98% 5% 10.96 10% 9.379 15% 8.962 Table 2 shows that using the same formic acid,with the increasing quality score of solution, silk powder grain diameter reduced .It illustrates that the higher the purity of formic acid is, the bigger crystallization role of silke is.It is the result of that formic can induce SF to crystallize.
Conclusions With measurement and analysis on solution viscosity of different solvent solutions and concentrations, we can draw a conclusion that the solution viscosity and stability of silk fibroin SFaqueous with formic acid must be better than that with CaCl2- C2H6O-H2O ternary system.XRD spectra explained diameter of SF dissolve in formic acid is smaller and the number of βcrystal is bigger.This method may be applied to the wound dressing and SF of electrostatic spinning of Nano-fiber for tissue engineering design and fabrication that using different solvents to control the size and structure of the SF.

Introduction Equal channel angular pressing/extrusion (ECAP/ECAE) is a novel processing technique for attaining ultrafine-grained bulk materials [1].
It has been shown that ECAP processing can play a dual role by both refining grain size and also significantly altering the precipitate morphology [2].
Theoretical analysis and experimental results show that route BC involves a redundant strain process and, hence, is not very effective for particle redistribution but is useful for grain refinement and for getting isotropic structures [4].
Furthermore, route BC-UD2, which follows route BC but the sample is put upside down before entering the channel once every two passes, proposed recently to be more effective for grain refinement and particle redistribution is also somewhat like route BA in the producing of anisotropy structures with orientated alignment of the particles [4].
Here, the numerals before the route names are the indicants of pass numbers. 4BA+4BC, for example, means a combination route of ECAP first pressing through 4 passes in route BA and followed through other 4 passes in route BC.

The forged intermetallic material has duplex microstructure consisting of γ-TiAl grains and lamellar (α2Ti3Al + γ-TiAl) grains.
Two diffusion mechanisms are possible: grain boundary diffusion and volume diffusion.
One can note that this analysis is from a grain in the junction zone.
The bright contrast shows that the phase has elements higher in atomic number.
But, the high percentage of V in this grain is indicative that it could be a β-Ti grain as V solubility is supposed to be higher in Beta Ti phase.

The grains are the cutting tools during lapping.
Possible material removal mechanisms in lapping [8] Material removal occurs as a result of the effect of the grain rolling in the contact zone between workpiece and plate surface or grains temporarily fixed in the lap surface.
The edges of lapping grains insert themselves into the workpiece material.
Through the vortex developing in the fluid film (pressure and suction forces), the lapping grains straighten themselves out and become engaged.
A constant supply of the slurry was maintained using the abrasive feed mechanism to provide a fresh supply of abrasive grains into the work zone.

Wear forms analysis of the self-sharpening fine super-hard abrasive tool Abrasive wear in general can be divided into three forms as shown in figure 1: abrasion wear of grind grain and its cutting edge (A in Fig.1), grind grain breakage wear (B in Figure 1) and grinding grain fall off (C in Fig.1) [5].
Grind grain breakage wear that occurred when the abrasive cutting edges in fracture fragmentations of abrasives.
Grinding grain fall which caused by bond bridge fracture.
In general, abrasive wear will happen when abrasive particle is toughness and abrasive tool is hardness, or grinding grain will be fall.
Research shows that Filler Zn will be dissolved in the FeCl3 solution, the structural strength of metal bond and abrasive are reduced and porous are generated in the metal bond, so dulling abrasive grains are self-shedding, new abrasive grains are exposed to achieve the purpose of dressing.

These steps result in the formation and growth of h¢(MgZn2) precipitates along the grain boundaries [4].
The grain sizes analysis was carried out using the linear intercept method.
However, semi-DC casts have fine equiaxed grain structure throughout their entire cross sections of average grain size of about 45mm.
The grain refinement is attributed to the effectiveness of the nucleation rate during solidification.
The number of the nucleus the GP zones and h¢ phase that can promote re-precipitation in the re-ageing step and they are increasingly according to XRD results.