Search results

It is founded that surface roughness deteriorates with higher sand grain size and vice versa.
The grain size of the sorted sand was quantified by AFS graininess number.
The shape of the sand grains was almost sphere with sphericity index of 0.91.
Only factor A (Sand number) is significant that have positive affect on the surface roughness.
The surface roughness of the casting improves when the AFS number of the sand grains increases.

Our attention is drawn to the partition of deformed grains hosting the emblematic component.
The orientation of the banded-type orientation gradient was analyzed in a cluster of two neighbouring rotated cube grains, grains A and B in Fig.2a, and in a grain of orientation (-1 2 4)<11 8 -1>, grain C in Fig.2b.
Present data showed the development of a substructure in {001}<110> grains but also in grains of which the orientation does not belong to the a- nor the g-fibre.
The {311}<136> components appeared both in the vicinity of the grain boundaries as well as in the grain interior of these orientations.
Acknowledgements This research was carried out under the project number MC5.07294 in the framework of the Research Program of the Materials innovation institute M2i (www.m2i.nl).

The average SiC grain size and bonding area of SiC grain increase during heat treatment at 1850°C.
A crack propagating before failure may have to go round SiC grains, and the number of grains it will go around depends on the size of the intergranular silicon and the SiC grains.
There are some smaller SiC grains surrounding larger primary SiC grains in the two samples before heat treatment (Fig. 2(a), (b)).
This could be due to the fact that in the case of a specimen containing grains of a far smaller size than their average size, the smaller grains grow to some limiting grain size close to the uniform grain size.
In addition, the fine SiC grains disappear.

The contribution of each element in the spectral analysis is normalized into a single number in term of the carbon equivalence to indicate the hardenability.
It consists of ferrite and pearlite grains.
A gradation in grain size beginning with large grains at the top to smaller grain sizes at the bottom of the weld zone is observed in all the multiple welded samples.
The grains of the microstructure progressively become finer as the number of runs increases and coarser as the interpass time increases.
It has been shown that the fusion zone and heat affected zone hardness decreases as both the number of weld and interpass time increases.

The normal DC casting has coarse grain, of which the edge is a small dendrite spacing with tiny dendrite arms, but the mixed crystal structure composed of coarse dendritic phase and fine crystal grains appears in the center.
The average grain size distribution on the cross section of the ingot is shown in Fig. 4.
The grain size of the normal DC casting gradually increases from 308μm at the edge to 470μm at the center.
The average grain size of the ingots applying the homodromous electromagnetic fields increases rapidly in the radial direction, and the average grain size of the ingots to which the reverse electromagnetic fields are applied remains between 149μm and 223μm.
It leads to inhibit dendrite growth, increase the number of crystal nuclei, promote the production of equiaxed grains, and refine grain.

The countries producing large volumes of grain use cereal cultures including wheat, corn, rye, millet to produce bioethanol.
However, widespread introduction of production technologies of biofuel in Kazakhstan, encounters a number of problems of both global, and regional character.
Use only of low-quality wheat going on a forage to cattle and the free rest of grain will allow making up to 1 billion liters (812 thousand tons) of bioethanol.
Only due to processing of the low-quality grain, which is annually formed in the course of production of grain crops, it is possible to make more than 3 billion l. biofuels.
Conclusion Now there is a number of the problems causing alarm of the international community accompanying development of production technologies of biofuel: – withdrawal from traditional agricultural land turnover under cultivation of biofuel monocultures that promotes falling of fertility of such lands, reduction in production of food vegetable raw materials in the certain countries, to increase in prices for the food at national and global level; – use for production of biofuel of food raw materials (grain, corn, sugar beet and reed, colza) that can also lead to increase in prices for the food in the world and, as a result, to increase in number of the starving people in the poorest countries.

A large number of theoretical works and practical studies are devoted to wear assessment issues.
Some results of studies on the wear of coated abrasives of various grain sizes and manufacturers are presented in the article. 1.
In this case, the mechanism of the coated abrasive wear will also differ from that of abrasive wheels, since there are different values of contact pressure, as well as the total number of abrasive grains in the machining interface.
The machining time (cycle) was 1 min; the number of cycles being 10.
This is due to the fact that at the time of the start of work, not all abrasive grains are grinding, but only the most protruding ones, which are the first to become dull or break out. 4.

When the extrusion temperature is up to 390°C, the grain size increases significantly, but the second phase precipitation along grain boundaries transforms into continuous and uniform-distribution precipitation within the grain.
When the temperature is 300ºC, big grains in magnesium alloy form new grains under the influence of stress, at the same time, relative rotation among grains causes imperfect dynamic recrystallization of the deformed structure, which eventually forms fine particles.
At 330ºC, some black second phase begin to precipitate along the boundary of the grains.
Since the pinning effect of the black second phase on the grain boundary prevents the grains from growing big, the grains becoming finer, which accounts for the increase of tensile strength.
When the extrusion ratio is 60, the grain has the smallest size (being about 3-5µm), the second phase in diffusion precipitation refines gradually and increases in number, and the tensile strength reaches to its highest.

With the same total reduction, strength rised as total pass number increased in multi-pass rolling.
The grain size of the as-extruded material is displayed in Fig.1 (a).
At temperature 400�, although heavy reduction can promote grain refinement, deformation energy produced by rolling accelerates grain growth, which leads to a balance between refinement and growth of recrystallized grains [3] Total pass number.
It shows that the grain size is nearly same in spite of different total pass number.
It is thought that more pass number will lead to worse mechanical properties because of grain growth during repeated heating between passes.

The grey particles distributed at grain boundaries or within grains are AlLi compounds (marked as B).
Among them, the grain size of alloy 1 is not uniform and the average grain size is 32.30 μm.
The average fine grain size is 6.66 μm, while the average coarse grain size is 38.60 μm.
The increase of grain number in per unit volume also leads to the gross deformation of alloys dispersing among more grains and the stress distributing more uniformly, thereby the ductility of the as-extruded alloys improves.
The as-extruded Mg-14Li-3Al-0.6RE alloy obtains the finest grain and the average grain size is only 4.28μm.