Search results

After the first studies of Kriven and Davidovits in the ‘70, the number of researches on the alkali activation process of alumino-silicates has largely increased in the last ten years, as geopolymers seem very attractive for a lot of applications in the industrial and civil engineering.
The main features of geopolymers are: (i) a large number of starting materials can be used as precursors if they contain a high content of SiO2 and Al2O3 in the amorphous state [7-8]; (ii) the consolidation process occurs at moderate temperature (from 20 up to 100°C); mechanical and physical properties can be tuned as function of process parameters such as the amount of the activating solutions.
Grain size distribution, determined by laser granulometry (Malvern Instrument), is reported in Fig. 1.
Grain size distribution of BWP.
Although both the geopolymers show some pores of large dimension (40-80 mm) due to the air entrapped during the mixing procedure (Figs. 3a and 3c), sample G2 exhibits a large number of pores with dimension in the range 5-30 mm, which are barely present in G5.

The software could reduce or even avoid a large number of manual tedious and boring modification processes.
The part family template is set up by using the principle of part family, and then the system compares the input number with the data of database by using the VC++ program.
Demonstrate the system interface Click on the button "chassis", modeling interface of vibration chassis appear, and then enter the number as a main driving dimension “Half of baseplate width”, as shown in figure 5.
Compare the input number with the data of database, and select the closest one to output.
Mechanical Engineering and Automation (2004) 1：19-22 [9] Shan BF, SF Basic study on drier by vibrating to mix grain, J.

After aging, this copper concentration allows producing a structure with the maximum number of precipitate particles of Al2Cu and, first of all, their metastable modifications (θ' and θ'') [8, 9].
A high volumetric share of particles of intermetallide compounds Al(Fe,Mn,Cu), Al2Cu are found on grain boundaries.
The recrystallization process is related to special boundaries between new formed and deformed grains [22].
The recrystallization starts in aluminum alloys after hot molding from the form of growing colonies of new grains 5-15 µm in size with high corner boundaries [23].
StJohn, Grain refinement of aluminum alloys: Part I.

The stoichiometry of this phase was established previously by chemical analysis of a large number of particles obtained by segregation from the melt [21].
As can be seen, the microstructure consists of equiaxed sintered grains, with a rather uniform grain size distribution.
Table 5.- Chemical composition determined by WDS in the SEM, of the equiaxed grain microstructure shown in micrograph of Fig. 5.
The formation of this molten solution allows speeding up of the formation of a sintered structure of equiaxed grains, achieving a rather homogeneous grain size distribution.
An equiaxed grain sintered microstructure composed of 35% Al9FeMnSiandAl9FeMn2Si intermetallics was obtained, with average chemical composition of 47.87 wt % Al, 10.99 wt % Si, 20.04 wt % Fe, and 21.10 wt % Mn.

The large and atomic bonding force is weakened, and the critical shear stress (CRSS) causes the dislocation slip reduced, which increases the number of slip systems at the same time.
It is shown that the grains were coarse and equiaxed, the second phase distributed along grain boundaries.
Compared with the homogenized microstructure, the shape and size of the grains did not change much, but the distribution was more inhomogeneous.
It can be seen that the "necklace" structure around the original grain was typical recrystallized grains, indicating that partial dynamic recrystallization occurred in this region.
The complete dynamic recrystallization was observed and the grains became finer and more uniform.

Strong effect of underneath layer on organic layer growth behavior of the subsequent layer has been discussed in a number of reported researches [18, 19].
The surfaces of CuPc layer on ITO has small grain and smooth surface while the surface morphology of CuPc layer on C60/ITO shows rough surface and has bigger grain than that of on bare ITO glass as shown in Fig. 4.
Surface morphology of CuPc on ITO shows smaller grain size than that on C60/ITO.
In addition the surface morphology of C60 layers on ITO and CuPc/ITO in Fig. 4 shows similar grain shape but has smaller grain size comparing to that deposited on CuPc layer.
Menon, Determination of the thermal activation energy and grain size of iron phthalocyanine thin films, Mater.

Recently, a number of DMWJ cracking incidents occurred in the PWRs nuclear power plants such as V.C.Summer plant, Oconee 1,3 and Ano 1[1-2].
The recrystallized features with extensive grain boundary migration are observed in all parts of the weld and buttering.
Also some large grains in the weld metal near Alloy52Mw/316L interface can be observed from Fig.6 (f).
It reveals a carbon depletion area, coarse-grained upper bainitic area and small ferrite/bainite grained area from A508/Alloy52Mb interface to A508 base metal.
As a result, the coarse grained heat affected zone (CGHAZ) and fine grained heat affected zone (FGHAZ) were formed separately.

In this paper, the phenomenon of steady-state cation demixing in yttria-stabilized zirconia in an electric field is examined for the case of an open system wherein the defects are everywhere close to internal surfaces which allow the Schottky-defect reaction to occur (very fine grain material).
Here, qA(B) is the number of charges on A(B).
The closed system might be expected to correspond to single crystal material whilst the open system would correspond to polycrystalline material having a very small grain size.
Summary The phenomenon of steady-state cation demixing in yttria-stabilized zirconia in an electric field was examined for the case of an open system wherein the defects are everywhere close to internal surfaces which allow the Schottky-defect reaction to occur (very fine grain material).

Metallographic investigations showed that microstructure of carbon steel wire after combined deformation is uniform and can be classified as ultra fine grain one.
It was proved that the combination of tension, compression, bending and torsion strains leads to the formation of ultrafine grain structure in carbon steel wire [10-14].
Stress-strain diagrams of medium carbon steel wire after drawing, bending (0 RPM) and combined deformation (drawing with bending and torsion) at different rate of torsion (numbers after Drawing mean the wire diameter in the initial state and after each drawing die) It is evident from the obtained results that deformation conditions influence the mechanical properties of the processed carbon steel wire in a different way.
Grains are elongated towards the deformation force.

Spin number in studied systems was Neff =512÷262144.
The values of a wave number and a character of amplitude and phase modulation were detected by means of mathematical apparatus of the spectral analysis based on the Fourier transformations [15].
A temperature in which uneven change in wave number of modulated structures occurs was taken as a transition temperature.
Selke, Monte Carlo coarse graining for the three-dimensional axial next-nearest-neighbor Ising model, Phys.
Binder, Critical Properties from Monte Carlo Coarse Graining and Renormalization, Phys.