Search results

The increase of mechanical attributes and resistance to fatigue load can be achieved by obtaining fine-grained structure with the size of grain under 10 µm.
The results of fatigue tests sloping branches of Wöhler curves are shown in the plot tension (τ) - the number of cycles to fracture (Nc) Fig. 2.
Table 3 Fatigue characteristics of aluminium alloy State Rm [MPa] τc104 [MPa] τc105 [MPa] τc / Rm 104 105 Initial state 274 ± 214 ± 165 0.78 0.60 ECAPed state 363 ± 242 ± 192 0.66 0.53 It is obvious from defined values that the ratio of τcNx/Rm decreased with increasing number of cycles.
On the other hand, in samples after ECAPed (Fig. 4 b) the fracture was highly dissected with fine-grain morphology and with the amount of fissile secondary cracks.
On the other hand, fracture surface after ECAPed is highly dissected with ultra-grained morphology.

It is a composite made by metal or alloy as the matrix, and various reinforced material recombined fiber, whisker and grain.
Table 1 Sample number, size and quantity of different parts of composite material Sample Number Size Quantity Top roll A1-A4 10×10×140 4 Central roll B1-B4 10×10×60 4 Bottom roll C1-C4 10×10×60 4 Central and original state roll (no heat treatment) D1-D4 10×10×60 4 The heat treatment was in box type resistance furnace with 650℃ preheat 15 minutes first, then heated up to 900℃, isothermal quenched by oil after 15 minutes.
Many tiny carbides distributed on the black troostite, some discontinuous reticular carbide scattered along the grain boundary.
The carbide included the various fine carbide dispersed in matrix and the network carbide on the grain boundary.
Conclusions (1) The metallographic microstructure of the original casting was fine carbide on the troostite, and the discontinuous network carbide scattered along the grain boundary; the metallographic microstructure of the forging and annealing was inhomogeneous sorbite and ferrite, and WC hard phase and alloy carbide distributed dispersively; the organization of the quenching and tempering was tempering martensite, carbides and residual austenite

Powder morphologies and grain size were directly imaged using scanning electron microscopy (LEO, LEO 1455VP, Cambridge, England).
At a clacination temperature as low as 800°C, the strongest reflections were apparent in the majority of the XRD patterns, which indicated the formation of a columbite phase of CoNb2O6 (A) that could be matched with JCPDS file numbers 32-0304.
This Co4Nb2O9 phase was indexable according to a hexagonal corundum-type structure, with a lattice parameter of a = 517 pm and c = 1412 pm, and space group P3c1 (no. 165), consistent with JCPDS file numbers 38-1457.
The average grain sizes were determined from the XRD pattern according to the Scherrer's equation B k D θβ λ cos = where D is the average grain size, k is a constant equal to 0.89, Bθ is the (3 1 1) peak angle, λ is the X-ray wavelength equal to 1.5406 Å and β is the half peak width.
The average grain size of Co4Nb2O9 powders was about 280 nm at 900 ° C, with a dwell time of 60 min.

Round stuffing grains are supposed to be buried in the basis.
If the volume rate of the grains is, then the effective dielectric constant and the effective permeability of composite can be written as: , (1) (2) respectively, where , are the dielectric constant and permeability of the stuffing grains, while ,are similar parameters for the basis.
Acknowledgment The project is supported by The Jiangsu Key Laboratory for New Ceramic and Its composite Materials, with the project number: Wjjqfhxc1200705.

Moreover, phenomena such as plastic deformation, residual stress and changes in grain structure occur around the cracks’ tips, which affect the process of crack propagation significantly.
X-ray diffraction, a method can reveal the changes in grain structure resulting from stress and plastic deformation is the most popular one.
This study is an attempt to establish a theory correlating the stress ratio with plastic deformation, residual stress and changes in grain structure at the crack’s tip.
In the two first tests, maximums loads of 16.24kN (test number: A-1) and 13.54kN (test number: A-2) were applied under a stress ratio of 0.1.
Furthermore, loads of 24.37kN (test number: B-1) and 20.30kN (test number: B-2) respectively were applied under a stress ratio of 0.4.

However, we still have numbers of difficulties, problems, and issues remaining unsolved, including the low reliability/cost-performance in practical uses, difficulty in characterizing the parameters that control the processing, sintering, and the properties of ceramics, problems in grain-boundary control/characterization, the deficiency of test results and practical experiences in the application of ceramic materials and their composites to bio-science/engineering, etc.
The symposium envisaged ten of technical sessions; (1) Processing and sintering, (2) Micro/nano-structure & grain-boundaries, (3) Ceramic science & engineering, (4) Structural ceramics, (5)Advanced refractories, (6) Porous ceramics, (7) Deformation, damage, and fracture, (8) Micro/nano-composites, (9) Functional ceramics, and ( 10) Applications.

Oxygen inward penetration through cracked scales formed during thermal cycling of FeCrAl alloys occurred mainly via oxide grain boundaries.
The latter is given in number of sputtering cycles.
D. 0 2 4 6 8 10 100 101 102 103 104 SIMS Intensity [counts per second] Sputtering time [number of cycles] 16-O+ 27-Al + 52-Cr+ 56-Fe + 0 1 2 3 0,0 0,2 0,4 0,6 0,8 1,0 16-16O 18-18O 43-Al16O 45-Al18O Normalized SIMS Intensity Sputtering time [number of cycles] Fig. 8.
The cracks exhibit well-developed grained structure which causes oxide penetration towards the substrates via oxide grain boundaries.
The oxygen penetrates across the scale towards the substrate via oxide grain boundaries also in cracks, since the oxide formed there exhibits grained structure.

Coal gangue as road engineering material can sovle the problems of energy saving and environmental protection.Experimental datas of grain size distribution,crushing value,slake durability index,expansivity,liquid limit index,plastic limit index and water absorption showed that its own characteristics are in line with the requirements of road engineering materials.
It also brings about economic, environmental social benefits.[6] Material properties Road materia experiments were conducted on coal gangue which piled up the life of 10 years, the data obtained are as follows(The following values for the mean test multiple samples,see Table1): Table1 Coal gangue various properties and numerical data Material properties Obtained numerical data Description Density 2.44 g/cm3 Grain size distribution Well graded particles Easy to obtain large density, with low compressibility and high strength Crushing value 29.1% <30%, indicated that’s easy to be crushed, after rolling surface is smooth and dense Slake durability index 96.25% Index is higher, the resistance of softening and disintegration is better Expansivity Particles below 0.5mm 18% All are less than 40%,showed that it is non expansive Particles below 5mm 27% Particles above 5mm 32.1% original sample 26% Liquid limit index 31.06% <50%，meet the requirements Plastic limit index
Table2 General factors of gangue used in road engineering in our country Number General factors Number General factors 1 C1 Investment rate of energy-saving road 12 C12 Quality of the construction workers 2 C2 Financing rate of energy-saving road 13 C13 Quality of managers 3 C3 Profit margin of coal gangue used in road engineering 14 C14 Material type 4 C4 Academic study of coal gangue used in road engineering 15 C15 Material price 5 C5 Propaganda of coal gangue used in road engineering 16 C16 Material sales 6 C6 Mixture ratio design of coal gangue in road engineering 17 C17 Research and develop for coal gangue used in different structure layer of road 7 C7 Energy saving material product design 18 C18 Research and development for construction technology of road with coal gangue 8 C8 National mandatory measures 19 C19 Development for
The grain size distribution of coal gangue is different and the separation process requires special technology knowledge and field, and the complicate process and transportation cost cause there are not many gangue suppliers in China,let alone the formation of the large-scale industrial chain.

DEM simulations of industrial ball mills show that the number of the low energy impact which cannot break ore particles is very much, and the large energy impact which can break ore particles in a single event is nonexistent or the number of impacts is too rare to affect the whole breakage.
It is assumed that impact intensity and corresponding impact number which were suffered by each ore grain in ball mill are same.
According to the actual mill length, it will take a number of days to complete the simulation, so such a reduction is necessary to make the simulation time feasible.
The throughput is calculated base on impact energies which were suffered by ore grain and breakage probability model.
The relative normal impact velocities distribution and corresponding impact number of media to each ore grain can be obtained from DEM modelling of the mill, as shown in Fig. 2, which can be used for calculating breakage probability.

TEM investigations identify these areas as structural defects between Si grains of differing stacking sequence.
However, due to the loss of the stacking information by the hexagonal Pr2O3 buffer, these Si films exhibit a large number of stacking twins.
The statement that there are no grains with opposite orientation existing can be done at least with a detection limit of about 1%.
We do not expect that there exist expanded Si grains with 511 orientation.
The dash-dotted line marks the expected orientation of the (-1-11) netplanes, when a grain with (-1-15) netplanes would be twisted in a surface-parallel orientation.