Search results

In the process of the test,S01 is broken when the cycle number of fatigue load is only 97 times and the load is 4.4706KN.S02 break quickly when the cycle number of fatigue load is only 45 times and the maximum load just reach 2.54KN, which means the material has been embrittled severely.
On the other hand, large numbers of experiments are required.
There is a great change in the microstructure and the binding force between the grain and the grain boundary is weakened

A series of coupons were tested with a number of different variable amplitude loading sequences which had distinct marker bands inserted to separate the individual segments of loading and enable them to be identified fractographically.
Each individual loading segment (i.e. a repeated number of the same cycle) in a block was related to the loading that created it.
When designing these types of sequences, the important point to bear in mind is that the crack is not flat and produces, for large grain materials, such as the 7050 plate material used here, a path within each grain that is highly correlated to the applied loading.
The sequences were designed to investigate: Sequence 2 – different ways of ordering a sequence, Sequence 3 – different ways of ordering a sequence plus the effect of crack closure, Sequence 4 – different numbers of interrupted cycles of the same amplitude and Sequence 5 – staircase effect of interrupted cycles.
These sequences contained variable and constant amplitude segments arranged in a number of different ways and were applied to both small crack and long crack coupons.

The intensity of the deep level PL is a complex function of the number of radiative centers and the number of centers limiting carrier lifetime.
Photoluminescence micro-mapping of SiC Room temperature photoluminescence mapping of defects in SiC has been reported by a number of authors [1,2].
The dark lines on the PL map are associated with crystalline defects such as low-angle grain boundaries, threading dislocations and interfacial misfit dislocations.

This caused by several factors i.e. increased porosity, grain zirconia cracked, zirconia reacted with HA to produce CaZrO3, β-TCP and α-TCP, HA matrix cracks because of the phase change of tetragonal-zirconia into monoclinic-zirconia.
The third strongest peak in the XRD pattern d=2.8167, d=1.8384 and d=3.4242 were characteristic of HA and closely matched with the JCPDS file number 09–432 of hydroxyapatite.
The first three peaks d=2.8916, d=3.6653 and d=2.6079 in the XRD pattern was characteristic of β-TCP and closely matched with the JCPDS file number 09-169 of β-TCP.
The first two peaks d=0.8895 and d=2.6048 in the XRD pattern was characteristic of β-TCP and closely matched with the JCPDS file number 09 – 169 of β-TCP.
Some causes of decreased compressive strength are increases porosity, bonding between HA and ZrO2 grains is not strong, zirconia cracks so that the HA as a composite matrix cracks (Fig. 4(b)) and formation of CaZrO3 [6] (a) (b) Figure 2.

However, with the aging time increasing, the coarse κ-carbides precipitating around the grain boundaries would deteriorate toughness, which lead to increase of the abrasive wear volume loss.
With the aging time increasing, the number of peeling pit decreases obviously, besides, the average width of groove is much narrow (Fig .3(c)).
After aging at 550 ℃ for 4 h, a larger peeling off appears in the austenitc grain boundary.
Prolonging the aging time could cause that the coarse κ-carbide produce along the austenite grain boundary.

Metallographic examination, performed on specimens of all segments of the tank, showed that microstructure of material is either fine-grained or striped ferrite-pearlite.
A large number of 3-70 mm long surface cracks was detected through the use of magnetic particle testing, carried out in accordance with standard [4] and acceptability criteria defined in standard [5].
a) fine-grained, sporadically striped, ferrite-pearlite microstructure b) striped ferrite-pearlite microstructure Fig. 4.
[12] EN ISO 643: Steels - Micrographic determination of the apparent grain size, European Committee for Standardization, 2012

The equations governing the conservation of mass, momentum, energy, and species in non-dimensional variables can be written as: Continuity equation: ∇ V=0 (1) Momentum equation: ∂V∂t+V∙∇V=-∇P+∇2V+1DaV (2) Energy equation: ρCr∂T∂t+V∙∇T=1Pr ∇λr∇T (3) The non-dimensional parameters in the above equations are Darcy number, Da=K/H2 , defining the micro-grain permeability, the Prandtl number Pr=νaf (fluid properties).
Comparison of average Nusselt number with literature results.
The related questions concern the identification of the global apparent permeability when the inner grain permeability is considered.
The permeability evolves from the grain permeability, when the macrocapillary disappears (weak threshold values), to higher values which seem fitting the A1 evolution for threshold values higher than 2.5.
Leong W.H., Hollands K.G. and Brunger A.P., “Experimental Nusselt numbers for a cubical-cavity benchmark problem in natural convection,” Int.

Single crystals of Zr(P1.25Se0.75) and partially substituted by Sc atom for Zr site of the ZrP2-xSex were also grain grown using high pressure technique.
Zr (powder, 98 %), Hf (powder, 99.9 %), Lu (powder, 99.9 %), Y (powder, 99.9 %), P (grain, 99.9999%) and Se (grain, 99.999%) were mixed and pelletized in a nitrogen-filled glove box.
Partial substitutions by scandium in A site for AP2-xXx (A=Zr; X= Se) single crystals were also prepared by a grain growth technique, the pellets were also put into BN crucibles and heated at ~2,050 ℃ under a pressure of approximately ~2.0 GPa or ~4.0 GPa maintained for 3.0 h and then rapidly quenched to room temperature.
By the grain growth technique using the high-pressure apparatus, single crystals of Zr(P1.25Se0.75) and (Zr0.5Sc0.5)PSe were obtained for the first time.
Acknowledgement This work partially supported by JSPS KAKENHI Grant-in-Aid for Scientific Research on Innovative Areas “Mixed anion” (Grant Number JP16H6439).

The property difference is mainly caused by vanadium through fine grain strengthening and precipitation strengthening.
The damage variable characterizes the coarsening of carbides resulting in the gradual reduction of the creep resistance, and the other damage variable characterizes the damage induced by the grain boundary cavities.
To achieve the parameter identification, six material constants are assumed to be the optimization variables, and the objective function LS is proposed based on the least square method, minimizing the error in the predicted and the experimental values of the creep strain: (2) where m is the number of the creep experimental curves, ni is the number of the data points on the ith experimental curve, αij is the scale factors to guide the optimization process, the superscripts pred and exp denote the predicted and experimental strain, respectively.
The creep damage of ferritic steels is mainly controlled by the damage variable which characterizes the damage induced by grain boundary cavities.

The zeolite samples were grained in a ball-mill, the grain fraction of size 0.2-0.31 mm was selected, washed with distilled water and dried at room temperature.
The grained sample of zeolite (0.6 g) was pre-treated with 20 ml of 0.5M solution of HCl during 24 h at a temperature of 20±1 ºC.
Taking into consideration the fact that Scandium in complex shows coordination number 6 and also according to [10] Sc(III) is almost in the form of neutral hydroxo-complex [Sc(OH)3(H2O)3] in solutions with pH 8.5 [Fig. 3].
An increase of the sorption capacity of zeolites calcined at the 300-350 ºC is connected with partial transformation of H-clinoptilolite, during the process which increases the number of OH-groups as is it shown in scheme [13] : Fig. 4.