Search results

But a few number of studies in particulate composites have been undertaken with particles and particle size distribution [6] .
Table 1 The physical properties of graphite blocks Samples Mean particle size of NG /(μm) Density /(g·cm-3 ) Tensile strength /MPa Bending strength /MPa Electrical resistivity /(μΩ·m) thermal conductivity /(W/m·K) ∥ ⊥ ∥ ⊥ NM-1 817 1.863 3.895 22.267 8.90 2.67 30.4 411.9 NM-2 425 1.909 6.807 26.712 7.23 2.58 50.2 498.2 NM-3 290 1.876 5.074 21.097 10.37 2.92 43.5 473.1 NM-4 198 1.870 4.593 19.269 10.93 3.47 31.4 452.9 NM-5 156 1.845 4.335 14.803 11.51 4.04 29.3 343.5 ∥ Parallel to the direction of pressure ，⊥Perpendicular to the direction of pressure Fig. 1 Typical PLM micrographs of graphite block Fig. 2 FESEM images of the fracture surface of graphite materials Electrical properties of composites The resistivity of graphite/mesophase pitch composites is affected by many factors, the main two of them are scattering of graphite grain boundary and concentration of carriers.
The scattering of graphite grain boundary will be narrowed as the graphitization degree of several samples increases, the concentration of carriers will be increased as the graphitization degree of several samples increases.

This sharp peak decreases and shifts towards larger sizes in the grip portion of crept sample (fig. 3b) due to primary coarsening of M23C6 particles at the high-angle grain boundaries.
The number of particles with sizes less than 100 nm decreases and large particles with sizes more than 500 nm appear on high-angle boundaries in the gauge portion of crept specimen (fig. 3c).
However, during long-term aging and creep the M23C6 carbides and Laves phase most likely lose their coherency with ferritic matrix previously and these grain boundary particles coarsen up to nearly the same sizes in the both portions of specimen.

A number of assessment methods were employed, including resistance drilling, to identify and quantify the extent of deterioration and potential impact on structural capacity.
Vertical side posts typically are set in notches in the top face of the sills, with a gap left so that the longitudinal wall planks can be nailed into the side grain of the floor planks.
Knots and slope of grain tend to be the grade-limiting defect for lumber in older structures, and nearly all of the structural lumber and timbers used in the construction of the two trams contained large knots and could not be assigned an overall high structural grade.

Meanwhile small austenitic grain size results in large number of high angle boundaries in the matrix which also can prevent the microcrack propagating. 20um Fig. 1.
At the same time through heat transferring and electromagnetic field migrating into the interior area, surface overheating phenomenon that results in the formation of coarse austenite grains can be avoided and temperature difference between the surface and the interior area is reduced.

The softening mechanisms (reversion, recrystallization and grain growth) of the temper-rolled austenitic stainless steel are explained for example in Refs. 7 and 8.
In the UHS steel, the cold formed structure transforms back to soft coarse grained austenite and the hardness increases gradually away from the weld metal.
The increase in number of welds from 1 to 4 increased the YSS by 4.2 and 3.8 times so the increase in YSS was more efficient with the AR steel.

The grain and sub-grain boundaries, the dislocation pipe and the micro-crack of oxide film become the short diffusion channel of metal ion, and S element can enter the matrix through these channels.
Because of the high defect concentration in the sulfide, the metal ions further diffuse outwards producing a large number of sulfides (Fig.6), and then the alloy is subjected to catastrophic corrosion.

Furthermore, grain boundary diffusion and/or grain boundary rotation are probably invoked.
The change in the number of contour fringes indicates a change in the magnetization of the particles during heating.

According to the machining accuracy requirement, a spherical electroplated diamond grinding wheel, Ø50mm in diameter and 60# of grain size, is adopted.
If the stiffness permits, a large cutting depth is suggested to diminish number of passes and to improve process efficiency.
As the rotational speed of workpiece increases, the cutting thickness of each abrasive grain on the wheel increases correspondingly, and so does the grinding force [7].

Results and Discussion Figure 1a shows the densification behavior of the first series samples 1 to 10 sintered at temperatures 1300 and 1500 0C; figure 1b - of the samples I to VI of second series sintered over temperature range from 1100 0C. 0,50 1,00 1,50 2,00 2,50 3,00 1 3 4 5 6 10 Sample number B u lk d en sity, g /cm 3 1300 1500 0,5 1 1,5 2 2,5 3 1100 1200 1300 1400 Temperature, 0C B ulk d ensity, g/cm3 I II III IV V VI Fig. 1.
The mullite (grey phase) grain sizes are in the range of 5 - 10 µm.
It may be supposed that crystallization takes place from nuclei in the formed liquid phase as well as the crystals grow on the grain boundary of pores and liquid.

Fig. 2 (a) shows spherical α-Fe2O3 cores are very uniform, stably dispersed and the average grain diameter of the particles is 80 nm.
Compared to α-Fe2O3 seeds, it is clear that the surface of typical spherical α-Fe2O3 /Ag core/shell structures in Fig. 2 (b) and (c) is not smooth, instead there are some flecks spreading on the surface, indicating that a large number of Ag particles may be included in theα-Fe2O3 nanoparticles.
The α-Fe2O3/Ag core/shell structures are very uniform, well dispersed and the average grain diameter of the particles is 95 nm.