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Design and fabrication requirements of the KIER ceramic heat exchanger Ceramic Heat Exchanger of KIER Number of tubes Tube length (m) Number of air passes Number of exhaust gas passes Tube spacing 168 1.2 2 1 Equilateral triangles Cooling fanCooling fanCooling fanCooling fanCooling fanCooling fanCooling fanCooling fan R.T.R.T.R.T.R.T. 1200120012001200ooooCCCC 2min.2min.2min.2min. 2min.2min.2min.2min. 1 cycle1 cycle1 cycle1 cycle 600 cycles600 cycles600 cycles600 cycles R.T.R.T.R.T.R.T. 1200120012001200ooooCCCC 2min.2min.2min.2min. 2min.2min.2min.2min. 1 cycle1 cycle1 cycle1 cycle 600 cycles600 cycles600 cycles600 cyclesResults and discussion Fig. 3 shows the SEM images of a polished surface of the reaction-bonded Si/SiC tubes.
Therefore, it is believe that homogeneous distribution of IGF β-SiC grains between original α-SiC grains is caused by high mechanical properties in KIER samples.
Iseki, "Transport of Fine-Grained β-SiC in SiC/Liquid Si Stem", Adv.
Iseki, "Formation and Transportation of Intergranular and Nodular Fine-Grained β-SiC in Reaction-Sintered SiC", Adv.
Iseki, "Strength Variation of Reaction-Sintered SiC Heterogeneously Containing Fine-Grained β-SiC", J.

The large number of polarization directions enables optimized crystallographic orientations to be established from grain to grain in the poling process and, in turn, results in anomalously high piezoelectric properties [9].
Then, it was performed a wide search in the ICSD structure data bank in order to initiating the Rietveld refinement with two phases in input files: Rhombohedral (R3mR - card number #77585) and tetragonal (P4mm - card number #90699).
The calcium content seems to promote the grain size enlargement, which exhibits some consequences on the dielectric and piezoelectric properties.
The grain size enhances for this sample can be due to the increasing in mass transport at grain boundary and the calcium modifier seems to induce that effect.
In spite of the lower weight loss and considerable sintered density for the PZT02Ca sample, the smaller grain size leads to electrical damages of the ceramic.

There is a slight increase and decrease, respectively, with the number of passes.
With increasing number of passes the influence of the starting texture diminishes.
The inhomogeneity decreases with the number of passes.
Its influence diminishes with increasing number of passes.
Zhernaov: Ultrafine Grained Materials III (Y.T.

The parent vesicles are constructed by coarse-grained lipid-like amphiphile molecules[4, 5].
A schematic representation of coarse-grained models.
The coarse-grained (CG) models are illustrated in Fig.1.
All the simulations are carried out in the NVT ensemble with constant particle number N, simulation box volume V, and temperature kBT=1.
The particle density is obtained by dividing the number of amphiphile in each slice by the slice volume.

The grain structure of both as deposited and annealed film shows a bimodal grain distribution with giant (~ 1μm) grains surrounded by smaller (~ 30 nm) grain.
Defects such as dislocations and growth twins are present in the largest grains.
The average grain size varies from 50 to 70 nm for the asdeposited films.
After annealing at 260°C during 20 hours under argon atmosphere, a significant increase in grain size are observed, as the smaller grains (< 30 nm) disappear.
(A full calculation of the profile of Fig.4a would require wave numbers larger than 100.)

In addition, the base material also contains refinement of grain elements, such as Nb, V, Ti, Mo, Cr, etc..
As the temperature decrease, the number of the large dimples is reduced, the size becomes smaller, and the depth becomes shallower.
The grain boundary is distributed with white proeutectic ferrite, and carbide free bainite is from the grain boundary to the grain, which is a granular bainite, a needle ferrite and a small amount of pearlite.
And acicular ferrite grain boundary angle is big, high angle grain boundary is intersected with each other during the crack growth process, therefore, high grain boundary is a great obstacle for the cleavage crack propagation[6], which is helpful to improve the low temperature impact performance of welded joints.
[6] Qiao Y , Argon A S .Cleavage crack-growth-resistance of grain boundaries in polycrystalline Fe-2 %Si alloy: experiments and modeling.

The textured hcp metals exhibit extensive mechanical anisotropy due to the inherent crystal anisotropy combined with limited number of slip systems [1].
It will be interesting to examine the effect of grain growth by annealing at higher temperatures and/or longer times.
TEM micrograph of the typical undeformed recrystallized Ti3Al2.5V is included in Fig. 8 which exhibits a small amount of β phase confined mainly to grain boundaries and the microstructure is devoid of dislocations with only a few grains showing the presence of isolated dislocations.
While distinct subgrains were observed at lower stress levels, they seem to disintegrate into uniform distribution in the grain matrix at higher stresses.
As in uniaxially loaded samples, low angle grain boundaries showed evidence of 'c+a' type dislocations.

The loading rate is 0.1, which satisfies the formula of quantifying the impact of inertia on the test, (is the strain rate, d the mean size of grains in the assembly, ρ the grain density, and ρ' the mean effective stress).
Node degree is the most basic feature of the network, referring to the number of edges associated with nodes [14].
With the increase of friction coefficient between grains, the sample is more and more prone to shear dilatancy, so the average degree is lower and lower.
When the shear stress reaches its peak, the number of 3-cycles changes from downward to upward, and at the same time the average length of the force chain begins to drop and the number of force chains begins to rise, which means that a large number of force chains are buckled.
Finally, the samples reach the critical state, and the number of 3-cycle tends to be stable.

Grain growth: Grain growth can be a major source of tensile stresses in thin films.
The driving force for grain growth is the reduction of the total grain boundary energy.
From the above discussion it is clear, that the net (observed) stress change in thin films upon annealing can generally result from a combination of a number of, possibly competing, sources of stress generation and relaxation.
Thus, volume diffusion of Cu from Pd grain boundaries to the Pd grains is negligible.
The intermetallic phase grows preferentially along the grain boundaries of the mostly columnar grains into the Sn layers due to enhanced diffusivity along grain boundaries.

Strain-induced martensite predominantly appears inside austenite grains at the intersection of shear bands.
In order to obtain the average martensite grain size the applied field should be sufficiently large to have a single magnetic domain inside the martensite grain [13].
Two main factors influence the martensitic transformation kinetics for a given composition; the grain size and the interstitial impurities [5, 14].
The austenite grain size can be controlled by adjusting the austenitization conditions at high temperature before cooling to room temperature.
Acknowledgements The authors are grateful to the Stichting voor Fundamenteel Onderzoek der Materie (FOM) and the Netherlands Institute for Metals Research (NIMR) (project number 02EMM30-3) in the Netherlands for providing financial support.