Search results

Next, the dressing operation is performed to expose the sharp grains by removing the bond materials surrounding the grains.
Thus, the bond materials and abrasive grains are heated by the thermal energy generated by the laser beam.
After truing, the dressing for the removal of the bond materials surrounding the abrasive grains is carried out on the trued wheel surface in order to expose the sharp grains as shown in Fig.1(b).
As for the wheel surface conditions after truing, the SEM images in Figure 4(b) show that the number of abrasive grains on the wheel surface decreased and that many pores disappeared after laser truing in comparison with the original surface conditions 2mm (see Fig. 3(b)).
Therefore, the successive dressing operations were performed under the conditions shown in Table 2 to carefully remove the bond materials surrounding each abrasive grain without damage to the grains so as to expose the sharp grains.

The average grain size of cast alloys was determined by a linear intercept method through a large number of measurements.
The average grain size was clearly found to decrease with increasing the Mg content, as shown in Fig. 5.
The reduced grain size is generally known to be desirable for restricting hot crack occurrence [8].
Mean grain size of as-cast Al-1Fe-0.5Si-xMg alloys References [1] F.
Tech., “Effect of grain refiner and grain size on the susceptibility of Al-Mg die casting alloy to cracking during solidification”, 209 (2009) p. 210-219.

On the microstructure picture, the massive grains distribute closely.
The point tested shows that the white grain in the picture is Al5O6N.
Figure 6-C shows that block grains and dense microstructure are formed when component M3 sintering in 1400°C.
The size of the grain is larger than other two pictures.
The block grain can also be observed.

Table.1 Main technical performance parameters of the compressor Type DW-34.7/（11.5-53）-X Device number C102B Medium fresh air Axis power[KW] 845 Motor power[KW] 900 1st piston stroke[mm] 280 Axis roat-speed[r/min] 333 1st export pressure [MPa] 2.75 1st import pressure[MPa] 1.15 2nd export pressure[MPa] 5.3 2nd import pressure[MPa] 2.75 1stimport temperature[℃] 40 1st max-piston force[t/cm2] 32 Theory volume flow[m3/min] 203.87 1st export temperature[℃] 125 Inhalation status[m3/min] 34.7 Actual volume flow[Nm3/min] 123.33 Interlocking-protection While pressure of lubricating oil is less than 0.12MPa, interlocking-protection will be started.
The region 1 (Fig.3a) is made from ferrite, pearlite, a large amount of loosen structure and serious contractive pinhole.The region 2 (Fig.3b) is constituted by the same micro-structure with the region 1,but the crystal grain is fine.The region 3 (Fig.3c) is composed of the same micro-structure with above two regions ,but there are a lot of intensive distribution cracks along the grain boundary and loose pinholes formation by metal, non-metallic precipitates.
A large number of endogenous FeO metal which take on regular crystal shape densely distributed along grain boundary asymmetrically and a great deal of micro-cracks along the grain are found in fig.9.10.
Besides, cracking of low-melting eutectic phase can be seen on the grain boundary which is microporous polymeric cracking along grains.
Through the analysis of microstructure and electron microscopy, it is found that there are a lot of intensive distribution cracks along the grain boundary, a large amount of loosen structure and serious contractive pinhole in crosshead, which reduce the strength of the material.

Table 2 shows the position of the 2q position, FWHM and grain size of the diffraction peaks of GaN NWs on Si (111).
Table 2. 2q position, FWHM and grain size of the diffraction peaks of GaN NWs on Si Plane 2q diffraction peak (°) FWHM (°) Grain size (nm) (002) 34.5 0.1968 42 (321) 41.6 0.1968 42 A HR-XRD pattern of the samples deposited on Au-coated Si substrate is illustrated in Fig. 2(b); and table 3 shows some details of the GaN NWs peaks on Au-coated Si substrate.
Stacking faults, high-order grain boundaries and twinning, are some examples, which often observed in GaN NWs [10, 14].
Fig. 3 PL spectra of the GaN NWs on (a) Si (111) and (b) Au-coated Si substrates, at room temperature (300K) The comb-like fibers of these NWs increase the number of luminescent centers, and increase the PL intensity.
Acknowledgments The authors gratefully acknowledge the financial support from Postgraduate Research Grant scheme (Number: 1001/PFIZIK/844014) Universiti Sains Malaysia.

Therefore, a number of fractures occurring in the concrete at the pre-stressing force transmission can be decreased approximately twice by means of decreasing the aggregate size (to the optimal one) and improving cohesion with cement stone.
If some grains of the dense aggregate in the concrete are replaced by a certain number of porous fractions, at centrifuging of such concrete mixture the directed movement of dense porous particles in relation to the cement paste occur inevitably.
The grains of the porous aggregate should perform its damping function in the centrifuged concrete as well.
These grains, remaining accidentally entrapped, will decrease the stiffness of the formed concrete structure in an external layer of the concrete ring.
The most important characteristics providing the efficiency of porous aggregates introduction into the composition of a centrifugally reinforced concrete mixture are the grain composition, well-developed surface and sufficient grain density with open porosity and, at last, the availability of the used material [21].

The most specific feature at various levels of strength improvement lies in significant increasing or retaining of steel plasticity indices through minimization of grain size, fine structure fragments, carbonitride particles, segregation deposition.
Maximum strength exhibited by steels is achieved through building up of fine-grained structures based on dislocation martensite in rolled stock with preset final properties and in finished products.
Microstructure of rolled stock as IDT-product in pearlite region, with the proviso that the chemical composition of steels is similar, can be obtained with a great variation of microstructure morphology within a wide range: from the normal with ferrite-pearlite colonies to the granular type with different percentages of pearlitized and spheroidized carbides or the type of all-quasi-pearlite type, with either minimized or fully eliminated carbide network, with either fine-grained or ultrafine-grained ferritic matrix.
The effect of formation of fine-grained carbonitride phases and favorable redistribution of alloying elements pertaining to the same assume great importance in the field of new concepts for simultaneous adoption of alloying process optimized by reduction of their contents and upgrading of fabrication/performance characteristics of steel in the form of rolled stock and finished articles. 1 2 3 4 5 6 7 8 9 10 VI I V V III II A B IV Harmonization of steel microstructure-phase composition gained in IDT-production in the context of overall grain structure refinement and favorable redistribution of chemical elements (carbide-forming ones, in particular) over the matrix spaces and inclusions as well as in the context of significant minimization of alloying through a decrease in the number and concentration of steel components, makes provisions for purposeful comprehensive or individual upgrading of practically any property of rolled steel.
Such properties are as follows: weldability, cold deformability, superficial and through hardenability, machinability, grindability, polishing ability, surface strengthening ability as well as practical design characteristics: viscoplastic behavior and stressstrain properties of engineering range, physical-chemical properties, number of cycles to failure and fatigue life, corrosion and wear resistance, ballistic and impact durability, stability against brittle fracture.

Then the tungsten grain size and volumetric distribution of a binder matrix were calculated from image analysis software (Image J).
Contiguity, CW = 2 NWW / (2NWW+NWB) (1) Where, NWW - Number of W-W interfaces per unit length, NWB - Number of W-B interfaces per unit length.
Lower the size of tungsten grain, the higher is tensile property of heavy alloys [5], thus WHA 1 having a lower grain size (26.135μm) showed higher tensile strength compared to WHA 2 (31.284μm).
German et al. [1] illustrated four possible modes of failure in WHA i.e., tungsten-tungsten grain boundary (W-W) failure; tungsten grain cleavage (W-Cleavage); tungsten-matrix interfacial separation (W-M); and matrix failure.
WHA with 93% W has shown smaller tungsten grain size, less matrix volume fraction and more contiguity than 90% W.

Results The sand under study consists of medium-sized, round, light yellow particles with inclusions from dark grains.
Despite the rather rounded shape of the grains, the particles have a developed surface morphology; aggregation is also observed, in which fine particles cover large grains.
In the crushed powders, a high aggregation is observed – small particles cover much larger grains.
Activity was determined by the method of determining the number of active sites Brønsted and amount of absorbed CaO.
Activity of sand depending on genesis Component Specific surface, m2/kg The amount of absorbed CaO, mg/g Number of active sites, g∙eq/g Quartz-feldspar sand 310 50,5 8,1 Quartz sand 314 50,1 9,2 Discussion Thus, the efficiency and genetic readiness of quartz-feldspar sand as a component of a composite binder has been proved.

On the other hand, out of a number of available thin-film deposition techniques, the sol–gel technique offers a number of unique features, such as purity, better homogeneity, excellent control over the stoichiometry of thin films, lower processing temperature, easier introduction of dopant for tailoring the properties, substrates with non-planer shapes, large area deposition, and more importantly, the process can be easily made on-line with the existing semiconductor processing module [10].
It was observed that the grains of the MgAl2O4 ceramic films were dense and uniform after annealing treatment.
Zone T was identified between the zone 1 and zone 2 and consists of densely packed fibrous grains without void boundaries.
Zone 3 (Ts/Tm>0.7) which the Ts is close to Tm possesses equiaxial grains with the deposited surface.
The dielectric constant is influenced by the grain size and crystallinity.