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Introduction Recently, a number of research into, and the manufacturing of, magnetic nanoparticles has been widely investigated in various applications such as magnetic seals in motors, magnetic inks for bank cheques and magnetic recording media.
However, the grain of MnFe2O4 was found to appear in the 20 MF sample with heated at 800°C and it slightly increases with increasing heat treatment temperature to1000°C.
The grain size was in a range of 0.5-1.0 μm regardless of the heat treatment temperature.

Ding studied grinding characteristics of K-type carbide with different grain sizes[3].
The surface of wheel used was observed by optical 3D microscope system with beyond depth of field (Keyence VHX-1000), and measured the number of grits per unit area by 100 times, just as Fig.6 shown, which is fluctuated in the range of 15~45, and it is equal to 26.3 by statistics.
Reference [1] LU Q Z, ZHANG F R, YU L X, in: The condition and trend of Ti(C,N) cermet[J],, submitted to Journal of Wuhan Institute of Science and Technology, China, 15(5):43-46 (2002) [2] Gui Jicai, in: Research on ELID grinding mechanism and cutting performance of Nano cemented carbide[J], submitted to Harbin Institute of Technology,China (2009) [3] DING C S, ZHAO Y J, DING Y L et al, in: Grinding performances on cemented carbides containing different sizes of grain[J], submitted to Diamond & Abrasives Engineering, China, (05):67-70 (2009)

Although China construction units in the field more, but only a handful of construction unit has introduced the foreign high pressure DTH drill, and supporting the use of drilling and percussion tools products mainly imports, domestic to φ382 (15 inches) DTH bit production are still in development stage, the developed products are mainly exist main body fracture, insert product defects such as grain, breaking away[3].
Main Technical Parameters ofφ382 DTH drill We to a large number of domestic and foreign materials at the forefront of DTH drill is introduced as the foundation, according to foreign 12-inch impacter and 15 inches high pressure data related to the product sample as well as the development of domestic φ382 (15 inches) paper summarizes DTH drill test data, and makes references to supporting the use of high pressure DTH drilling rig based numerical wind pressure, gas consumption, etc, its main technical parameters of limit index calculation is as follows: 2.1 Bit impact energy According to materials, drilling alloy tooth broken rock column, every minimal energy is 14 joule per tooth, inherit the maximum energy of 72 joules/tooth, the tooth bit each column energy can be in 14-72 (joules/teeth), the impact energy calculation is reliable.
Strength [MPa] 1608 1350 +258 yield Strength [MPa] 1180 1060 +120 Elongation [%] 14 17 -3 Reduction of Area [%] 48 54 -6 Impact Energy Akv [J] 36 60 -24 From table 5 shows that the development of new domestic large diameter high pressure DTH bit 20CrMnSiNi2MoA materials on the tensile strength and yield strength is higher than similar foreign products 4330 mod materials, development of new materials on the resistance to overload ability is better than that of similar foreign products materials; And new material percentage elongation, reduction of area, impact value is low, show the development of new materials in some poor ability to resist crack instability expansion, therefore, we to material smelting, forging, heat treatment process was put forward strict requirements, the main measures mainly has: (1) Product size each transition cross section must be rounded; (2) Within the overall machining precision up to 3.2; (3) The surface and inner hole are all shot blast; (4) Refinement of grain

Number Heat treatment process Corrosion rate/ g/m2·h G28-A G28-B F-4 560℃/8h, air cooling 2.77 0.62 F-5 580℃/8h, air cooling 2.447 0.684 F-6 580℃/4h, air cooling 2.35 0.66 F-7 580℃/2h, air cooling 2.36 0.65 F-8 600℃/8h, air cooling 2.79 0.684 F-9 650℃/8h, air cooling 7.87 9.91 F-0 Applied alloy 2.81 0.52 Microstructural observation and analysis.
Seen from Fig.7, Fig.8 and Fig.11, microstructure of C-276 alloy under 580℃/8h heat treatment process was mainly relatively uniform austenite, and the precipitation phase was found in grain boundaries and grain under 500X; There were many point pericipitates in microstructure of C-276 alloy under 650℃/8h heat treatment process, and pericipitates lined strip, which affected the corrosion resistance of alloy.

By calculating the reduction rate of grains with different particle diameter, cohesion effects of SINOCLEAN cohesion unit for different size particles is analyzed.
The particle reduction ratio of particles with diameter 1.0~8.5μm is in negative trend, i.e., passing through the condensation unit, the count concentration of particles within the size range increases, wherein the condensation ratio of grains with diameter in the range of 6.5 to 8.5μm increases at most.
It showed that after passing SINOCLEAN agglomerator, the aggregation phenomenon of particles within the range of 0.5~1.0μm occurs more obvious, but causing the number concentration of particles within the range of 1.0~8.5μm increased significantly.

It can be seen from the figures that a large number of fine cellular grains are distributed as a "fish scale" shape, which is the typical morphology of selective laser melting technology formed after the solidification of laser scanning molten pool.
The difference of cooling rate between the edge and the center of molten pool leads to the uneven distribution of these grains in the banded structure

Such a film is advantageous for sensor devices since it has a large surface/volume ratio and thus has a large number of the reaction sites on the surface.
In the previous paper, we showed that the response can be fitted by a double-exponential function of time, which indicated that the sample resistance is controlled by a Schottky barrier at the boundary between the grains [8].
Hydrogen gas is considered to remove the fixed negative charge at the surface or grain boundary by the reaction H2 + O− = H2O + e− (3) where O− is the negatively charged oxygen atom, and e− a conduction electron.

Introduction Superabrasive grinding wheels commonly are consisted of metal bond, resin bond or vitrified bond wheels with grains of diamond or Cubic Boron Nitride (CBN).
Summary The dressing operation of superabrasive wheel is one of most important process for protruding the grains of wheel to improving the efficiency of grinding process.
Characterization of dressing processes by determination of the collision number of the abrasive grits.

Polishing speed, depth of penetration, feed rate, wheel properties such as abrasive material and abrasive grain size, are the dominant parameters for the spherical polishing process, as shown in Fig. 1.
As mentioned, the main spherical polishing parameters having significant effects on surface roughness, are the speed of the polishing ball, abrasive material, abrasive grain size, feed, stepover distance and the depth of penetration etc.
The S/N ratio, η, is defined by the following equation [8],       −= −= ∑= n i iy n stic characteri quality square mean 1 2 10 10 1 log10) (log10η (1) iy : observations of the quality characteristic under different noise conditions n : number of experiment The optimization strategy of the smaller-the better problem is to maximize η defined by equation (1).

The improved dynamic E&S vector hysteresis model, proposed in this paper, approximates a non-elliptic B-waveform B=(BR, BT) to an elliptic one b=(bR, bT) of which the geometric parameter p=(Bm, α, φ) is defined as follows: (3) and the axis ratio α is determined by minimizing least square error between B(τ) and b(τ) defined as: (4) where NB is the number of sampling points.
Mauchi, “Magnetic characteristic analysis measurement of three-phase generator utilizing grain-oriented silicon steel sheets,” International Journal of Applied Electromagnetics and Mechanics, vol. 33, pp. 415-422, 2010
Koh, “A generalized Chua-type vector hysteresis model for both the non-oriented and grain-oriented electrical steel sheets,” IEEE Trans.