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1.
Y2O3 + Nd2O3 co-stabilized ZrO2-based composites with 40 vol% WC were fully densified by pulsed electric current sintering (PECS) at 1350 °C and 1450 °C.
The influence of the PECS temperature and Nd2O3 co-stabilizer content on the densification, hardness, fracture toughness and bending strength of the composites was investigated.
The best combination of properties was obtained for a 1 mol% Y2O3 and 0.75 mol% Nd2O3 co-stabilized composite densified for 2 min at 1450 °C under a pressure of 62 MPa, resulting in a hardness of 15.5 ± 0.2
GPa, an excellent toughness of 9.6 ± 0.4 MPa.m0.5 and an impressive 3-point bending strength of 2.04 ± 0.08 GPa. The hydrothermal stability of the 1 mol% Y2O3 + 1 mol% Nd2O3 co-stabilized ZrO2-WC (60/40) composites was compared with that of the equivalent 2 mol% Y2O3 stabilized ceramic. The double stabilized composite did not degrade in 1.5 MPa steam at 200 °C after 4000 min, whereas the
yttria stabilized composite degraded after less than 2000 min. Moreover, the (1Y,1Nd) ZrO2-WC composites have a substantially higher toughness (~9 MPa.m0.5) than their 2Y stabilized equivalents (~7 MPa.m0.5). 相似文献
2.
S. Y. Chang L. C. Tsao M. W. Wu C. W. Chen 《Journal of Materials Science: Materials in Electronics》2012,23(1):100-107
In this work, Sn3.0Ag0.7Cu (SAC) composite solders were produced by mechanically intermixing 0.5 wt% Al2O3 nanoparticles into Sn3.0Ag0.7Cu solder. The formation and growth kinetics of the intermetallic compounds (IMC) formed during
the liquid–solid reactions between SAC-0.5Al2O3 composite solder and Cu substrates at various temperatures ranging from 250 to 325 °C were investigated, and the results
were compared to the SAC/Cu system. Scanning electron microscopy (SEM) was used to quantify the interfacial microstructure
for each processing condition. The thickness of interfacial intermetallic layers was quantitatively evaluated from SEM micrographs
using imaging software. Experimental results showed that IMC could be dramatically affected by a small amount of intermixing
0.5 wt% Al2O3 nanoparticles into Sn3.0Ag0.7Cu solder. A continuous elongated scallop-shaped overall IMC layer was found at SAC/Cu interfaces.
However, after the addition of Al2O3 nanoparticles, a discontinuous rounded scallop-shaped overall IMC layer appeared at SAC-0.5Al2O3/Cu interfaces. Kinetics analyses showed that growth of the overall IMC layer in SAC/Cu and SAC-0.5Al2O3/Cu soldering was diffusion controlled. The activation energies calculated for the overall IMC layer were 44.2 kJ/mol of SAC/Cu
and 59.3 kJ/mol for SAC-0.5Al2O3/Cu soldering, respectively. This indicates that the presence of a small amount of Al2O3 nanoparticles is effective in suppressing the growth of the overall IMC layer. 相似文献
3.
Weeraya Somphan Nuchjarin Sangwong Teerapon Yamwong Prasit Thongbai 《Journal of Materials Science: Materials in Electronics》2012,23(6):1229-1234
The electrical properties and dielectric response in Na1/2Y1/2Cu3Ti4O12 ceramic prepared by conventional solid-state reaction method and sintered at 1,090 °C for 5 h were investigated as functions
of frequency and temperature. Main phase of Na1/2Y1/2Cu3Ti4O12 with CaCu3Ti4O12-like crystallographic structure and CuO secondary phase were observed in the X-ray diffraction pattern. Abnormal grain growth
was observed just as observed in CaCu3Ti4O12 ceramics. The Na1/2Y1/2Cu3Ti4O12 ceramic exhibits a high ε′ of ~2.04 × 104 at 20 °C and 1 kHz and low tan δ (with the minimum 0.080 at 5 kHz). Impedance spectroscopy analysis reveals that Na1/2Y1/2Cu3Ti4O12 ceramic is electrically heterogeneous, consisting of semiconducting grains and insulating grain boundaries. Giant ε′ response
in Na1/2Y1/2Cu3Ti4O12 ceramic is therefore attributed to an internal barrier layer capacitor effect. 相似文献
4.
M. A. Borik M. A. Vishnyakova V. P. Voitsitskii A. V. Kulebyakin E. E. Lomonova V. A. Myzina V. V. Osiko V. A. Panov 《Inorganic Materials》2007,43(11):1223-1229
We have studied the effect of composition and growth conditions on the structure and properties of 2.5–5 mol % Y2O3 partially stabilized ZrO2 crystals grown by directional solidification in a cold-wall crucible. The phase composition and density of the crystals have been determined. The crystals are shown to be uniform in composition, with local changes in Y2O3 content within ±0.5 mol %. The dimensions and quality of the single crystals are influenced by the growth conditions. 相似文献
5.
E. V. Dudnik A. V. Shevchenko A. K. Ruban V. P. Red’ko L. M. Lopato 《Inorganic Materials》2010,46(2):172-176
We have studied the properties of nanocrystalline ZrO2〈3 mol % Y2O3〉 and 90 wt % ZrO2〈3 mol % Y2O3〉-10 wt % Al2O3 powders prepared via hydrothermal treatment of coprecipitated hydroxides at 210°C. The results demonstrate that Al2O3 doping raises the phase transition temperatures of the metastable low-temperature ZrO2 polymorphs and that the structural transformations of the ZrO2 and Al2O3 in the doped material inhibit each other. 相似文献
6.
T. H. Chuang M. W. Wu S. Y. Chang S. F. Ping L. C. Tsao 《Journal of Materials Science: Materials in Electronics》2011,22(8):1021-1027
To improve the properties of the eutectic Sn3.5Ag0.5Cu lead-free solder, various amounts of mixed nano-Al2O3 particles were added. The microstructure, thermal analysis, density, thermal expansion coefficient (CTE), and mechanical
behavior were studied. The results of differential scanning calorimetry (DSC) indicate that the melting point of the composite
solder doped with nano-Al2O3 particles is slightly higher that of the Sn3.5Ag0.5Cu lead-free solder and has a eutectic peak. The Sn3.5Ag0.5Cu composite
solders exhibited lower density values and thermal expansion coefficient (CTE) values than did the unreinforced solder matrix.
Compared to solder without the addition of nano-Al2O3 particles, the formation of dendritic β-Sn grains, the Ag3Sn phase average size, and the spacing of lamellae decreased significantly in the composite solder matrix. The mechanical
properties also improved with increasing weight percentages of nano-Al2O3 particles. However, the ductility of the Sn3.5Ag0.5Cu composite solder decreased. For the addition of 1 wt% nano-Al2O3 particles, microporosity was observed both at and along the grain boundary regions, coupled with the presence of second-phase
particles (i.e. nano-Al2O3 and Ag3Sn). 相似文献
7.
M. A. Borik V. T. Bublik M. A. Vishnyakova A. V. Kulebyakin E. E. Lomonova V. A. Myzina F. O. Milovich V. V. Osiko N. Yu. Tabachkova 《Inorganic Materials》2012,48(2):156-160
The structure of partially stabilized zirconia crystals has been studied by transmission electron microscopy before and after
annealing. Structural characterization of Y2O3-doped (2.8 to 4 mol %) zirconia before annealing showed that all of the samples consisted of twin domains whose size was
dependent on the stabilizer content. Annealing at 2100°C increased the domain size in the composition range 2.8–3.7 mol %
Y2O3 and reduced it at 4 mol % Y2O3. These structural changes allowed us to determine the position of the representative point relative to the phase boundary
in the equilibrium phase diagram of the system. 相似文献
8.
E. Yu. Anikina V. N. Verbetsky A. G. Savchenko V. P. Menushenkov I. V. Shchetinin 《Inorganic Materials》2017,53(10):1009-1012
Interaction of hydrogen with the intermetallic compound Nd2Fe17 has been studied for the first time by calorimetry using a differential heat conduction calorimeter coupled to a Sieverts apparatus. Hydrogen absorption and desorption reactions were run at 200°C, and two types of data were obtained: p–C–T and ΔH–C–T (where p is the equilibrium hydrogen pressure, C = H/Nd2Fe17, ΔH is the reaction enthalpy, and T is the measurement temperature). The p–C–T curves obtained for the hydrogen absorption and desorption processes have no plateau or two-phase region, in contrast to what is characteristic of the formation of a hydride phase. At the same time, the ΔH(C) curves have a few portions where the enthalpy of reaction between hydrogen and the intermetallic compound remains constant: 0 < C < 2.0, with ΔH abs =–85.05 ± 0.65 kJ/mol H 2; 2.0 < C < 2.7, with ΔH abs =–80.64 ± 1.00 kJ/mol H2; and 1.9 < C < 2.7, with ΔH des = 76.48 ± 0.85 kJ/mol H2. The data obtained in this study suggest that positions 9e and 18g in the intermetallic compound are occupied by hydrogen in a particular order. 相似文献
9.
X. Wang Y. C. Liu Z. M. Gao 《Journal of Materials Science: Materials in Electronics》2011,22(1):14-19
The effect of the Bi content on the formation of intermetallic compounds (IMCs) layers between the Sn-xBi-0.9Zn-0.3Ag lead-free
solder (with x = 1, 2, 3 and 4, in weight percent, hereafter) and Cu substrate was investigated. The structure of the IMC layer in the soldered
interface varies apparently with increasing the Bi content. When the Bi content is 1 wt%, the interface soldered is consisted
of CuZn and Cu6Sn5 IMC layers, which are separated by an intermediate solder layer. As the Bi content increases, the spalling phenomenon tends
to disappear. Moreover, the layer between the Sn-2Bi-0.9Zn-0.3Ag solder and Cu substrate is thicker than others. The evolution
of the soldered interfacial structure could be attributed to the existence of Bi. 相似文献
10.
Linhui Gao Yue An Hongliang Zhu Lun Wang Jianjun Chen Naiyan Wang Guofu Ou 《Journal of Materials Science》2011,46(5):1337-1340
This article presents the synthesis and photoluminescence (PL) properties of Y2Zr2O7:Tb3+. The Tb3+-doped Y2Zr2O7 zirconates were successfully synthesized by a hydrothermal process at 200 °C for 20 h. X-ray diffractometer (XRD) patterns
revealed that all of the products were phase-pure with the fluorite structure. PL study showed that the Y2Zr2O7:Tb3+ phosphors exhibited obvious PL emission peaks which located at 490, 545, 585, and 623 nm; the dominant emission located at
545 nm is assigned to 5D4 → 7F5 transition. Furthermore, Tb3+-doping concentration strongly affected the PL properties, and the quenching concentration is 5 at.%. 相似文献
11.
Wei-Wei Yang You-Ying Di Zhen-Fen Yin Yu-Xia Kong Zhi-Cheng Tan 《International Journal of Thermophysics》2009,30(2):542-554
Potassium benzoate C7H5O2K (CAS Registry No. 582-25-2) was synthesized by the method of liquid phase reaction. Chemical and elemental analyses, FTIR,
and X-ray powder diffraction (XRD) techniques were applied to characterize the composition and structure of the compound.
Low-temperature heat capacities of the compound were measured by a precision automated adiabatic calorimeter over the temperature
range from 78 K to 398 K. A polynomial equation of the heat capacities as a function of temperature was fitted by the least-squares
method. Smoothed heat capacities and thermodynamic functions of the compound were calculated based on the fitted polynomial.
In accordance with Hess’s law, a reasonable thermochemical cycle was designed, and 100 mL of 1 mol · dm−3 NaOH solution was chosen as the calorimetric solvent. The standard molar enthalpies of dissolution for the reactants and
products of the supposed reaction in the selected solvent were measured by an isoperibol solution-reaction calorimeter. Finally,
the standard molar enthalpy of formation of the title compound C7H5O2K (s) was derived to be -(610.94 ± 0.77) kJ · mol−1. 相似文献
12.
The formation and crystallization behaviors of a mechanically alloyed Al75Ni10Ti10Zr5 amorphous alloy were studied by X-ray diffraction, transmission electron microscopy, and differential scanning calorimetry
in the present study. The effective activation energy of the crystallization was determined by the Kissinger and Ozawa equations,
respectively. The two equations yield close results and the average activation energy is 252 ± 13 kJ/mol. The resultant crystalline
products were Al and Al3Ni, and the crystallization mechanism is two- or three-dimensional nucleation and growth controlled by the diffusion of atoms.
The thermal stability of the alloy was evaluated by a continuous transformation diagram obtained by the extended Kissinger
equation. 相似文献
13.
A. A. Sharif 《Journal of Materials Science》2010,45(4):865-870
Oxidation behavior of MoSi2 was investigated in air over the temperature range of 1400–1700 °C. Spallation of the SiO2 scale did not occur at any temperature, and Mo5Si3 formation did not happen below 1700 °C. A change in the rate-controlling mechanism was detected within the temperature range
of this study. Activation energy for oxidation of MoSi2 at high temperatures was determined to be 204 kJ/mol. This value is less than the value of activation energy for oxidation
of MoSi2 controlled by diffusion of O2 through amorphous SiO2 layer reported at lower temperatures. The decrease in activation energy is attributed to the increased degree of crystallization
of amorphous silica to β-cristobalite at high temperatures resulting in enhanced O2 diffusion through SiO4−4 tetrahedral structure. 相似文献
14.
Liang Fang Zhao Yang Hui Zhang Chunchun Li Xiyang Peng Changzheng Hu Dongjin Chu 《Journal of Materials Science: Materials in Electronics》2011,22(9):1208-1212
Polycrystalline samples of Ba4Ln2Fe2Ta8O30 (Ln = La and Nd) were prepared by a high temperature solid-state reaction technique. The formation, structure, dielectric
and ferroelectric properties of the compounds were studied. Both compounds are found to be paraelectrics with filled tetragonal
tungsten bronze (TB) structure at room temperature. Dielectric measurements revealed that the present ceramics have exceptional
temperature stability, a relatively small temperature coefficient of dielectric constant (τ
ε
) of −25 and −58 ppm/°C, with a high dielectric constant of 118 and 96 together with a low dielectric loss of 1.2 × 10−3 and 2.8 × 10−3 (at 1 MHz) for Ba4La2Fe2Ta8O30 and Ba4Nd2Fe2Ta8O30, respectively. The measured dielectric properties indicate that both materials are possible candidates for the fabrication
of discrete multilayer capacitors in microelectronic technology. 相似文献
15.
Venugopalan Anbarasu Appasamy Manigandan Thangavelu Karthik Kandasamy Sivakumar 《Journal of Materials Science: Materials in Electronics》2012,23(6):1201-1209
The synthesis and characterization of Y2−xFexO3 (where x = 0–0.3) compounds has been carried out for their importance in the field of multiferroic materials. The powder
X-ray diffraction reveal that the compounds Y1.95Fe0.05O3, Y1.9Fe0.1O3, Y1.85Fe0.15O3 and Y1.8Fe0.2O3 crystallize in tetragonal structure whereas Y1.75Fe0.25O3 and Y1.7Fe0.3O3 compounds crystallize in orthorhombic structure. The change in crystal system with respect to the concentration of Fe may
be attributed to the variation in occupancy position of Fe3+ into the Y3+ site of Y2O3 system. Variation in crystal structure, surface morphology and composition was studied by micro-Raman analysis, SEM and EDX
analysis. The shift in intense Raman signals from 426 to 385 cm−1 confirms the change in the crystal structure of the prepared compounds. Further it is also identified that the Eg mode of vibration is the dominant in the Fe substituted compounds. The substitution of Fe in the Y2O3 system leads to the increase in the intensity of resonance band, which indicates a large polarisability variation in the
Y2−xFexO3 compounds. Diffused reflectance studies show a red shift in energy gap values while increasing the concentration of Fe. The
room temperature magnetization and electron paramagnetic resonance studies reveal that the incorporation of Fe in the Y2O3 system leads to magnetic phase change from diamagnetic to ferromagnetic. The electric polarization studies imply that the
substitution of lower ionic radii element Fe3+ in the Y3+ site leads to distortion in the lattice and show the way to spontaneous dipole moment and it was found that the Y1.8Fe0.2O3 compound exhibits the possibility of multiferroic behaviour. Therefore this paper explores the possibility of inducing ferromagnetic
and ferroelectric behaviour in the Fe substituted yttrium oxide system. 相似文献
16.
J. C. Leong L. C. Tsao C. J. Fang C. P. Chu 《Journal of Materials Science: Materials in Electronics》2011,22(9):1443-1449
The effects of nano-TiO2 particles on the interfacial microstructures and bonding strength of Sn3.5Ag0.5Cu composite solder joints in ball grid array
packages with immersion Sn surface finishes have been investigated. Metallography reveals that addition of nano-TiO2 particle retarded wicker-Cu6Sn5 IMC formed in the Sn3.5Ag0.5Cu composite solder joints. The thickness of the interfacial intermetallic compounds of the solder
joint was reduced with increased additions of nano-TiO2 particles (0.25–1.0 wt%), but further additions up to 1.25 wt% decreased the beneficial influence. This indicates that the
presence of a small amount of nano-TiO2 particles is effective in suppressing the growth of the intermetallic compounds layer. In addition, the shear strength of
the soldered joints was improved by larger nano-TiO2 particle additions, with the peak shear strength occurring at 1.0 wt% of nano-TiO2 particles into the Sn3.5Ag0.5Cu solder. The fracture mode also changed with increased amounts of nano-TiO2 particles. 相似文献
17.
Shengliang Zhong Shijin Wang Huaping Xu Haoqing Hou Zubiao Wen Ping Li Shangping Wang Rong Xu 《Journal of Materials Science》2009,44(14):3687-3693
Uniform spindlelike Y(OH)3 nanorod bundles were successfully prepared for the first time via a simple hydrothermal method at 200 °C for 12 h with the
presence of Na2H2EDTA · 2H2O (EDTA). Scanning electron microscope (SEM) images show that the obtained Y(OH)3 spindlelike nanorod bundles have a length of about 11 μm and a diameter of about 2 μm in the middle part. The nanorod bundles
are composed of numerous nanorods, and all these nanorods are orientationally aligned and grow uniformly along the bundles.
The individual nanorod is with typical width of about 100 nm, thickness of about 40 nm, and length longer than 1 μm. The effects
of reaction temperature, reaction time, and the concentration of NaOH and EDTA on the sizes and morphologies of the products
have been investigated. The possible formation mechanism of the nanorod bundles was suggested. Spindlelike Y2O3 nanorod bundles were obtained after thermal treatment of the as-obtained Y(OH)3 nanorod bundles at 700 °C for 4 h. X-ray powder diffraction (XRD) results demonstrate that the as-prepared Y(OH)3 and Y2O3 are attributed to hexagonal phase and cubic phase, respectively. Eu3+ doped Y2O3 nanorod bundles were also prepared and their photoluminescence (PL) properties were investigated. 相似文献
18.
The manganese iron cyclotetraphosphate (MnFeP4O12) was synthesized through one-step thermal synthesis at 700 °C using the mixing of manganese and iron metals and phosphoric
acid in the presence of water–acetone media. Both FTIR and XRD results indicate the cyclotetraphosphate (P4O12
4−) structure and a pure monoclinic phase with space group C2/c (Z = 4). The morphology and crystallite size for the MnFeP4O12 obtained from SEM data and X-ray line broadening show non-uniform particles and 30 ± 9 nm, respectively. The magnetic study
of the synthesized MnFeP4O12 shows superparamagnetic behavior, which is important for specific application. Some physical properties of the synthesized
MnFeP4O12 powder presented for the first time are comparable with those from individual M2P4O12 (M = Mn and Fe) and a binary metal compound as CoFeP4O12. 相似文献
19.
In this study, four kinds of melt-processed YBCO samples were fabricated with the MPMG procedure. The compacted powders were
located on a crucible with a buffer layer of Y2O3 to avoid liquid to spread on the furnace plate. Their microstructures were defined by XRD analysis and polarized light optical
microscopy. The microstructure investigations indicated that the 123 grains were very big and fine and dispersed 211 particles
remained in the samples. Resistivities of the samples were measured by a standard continuous dc four-probe method. Magnetization
measurements were made and flux jumps were observed at a relatively higher temperature for Y1060. The critical current density,
J
c
, values of the samples, measured by VSM in 5 T magnetic field, exceeded 0.6×103 A⋅cm−2 at 77 K and 4 T. 相似文献
20.
Sang-Min Lee Jeong-Won Yoon Seung-Boo Jung 《Journal of Materials Science: Materials in Electronics》2016,27(2):1105-1112
The electromigration behavior of low-melting temperature Sn-58Bi (in wt%) solder joints was investigated with a high current density between 3 and 4.5 × 103 A/cm2 between 80 and 110 °C. In order to analyze the impact of various substrate metallizations on the electromigration performance of the Sn-58Bi joint, we used representative substrate metallizations including electroless nickel immersion gold (ENIG), electroless nickel electroless palladium immersion gold (ENEPIG), and organic solderability preservatives (OSP). As the applied current density increased, the time to failure (TTF) for electromigration decreased regardless of the temperature or substrate metallizations. In addition, the TTF slightly decreased with increasing temperature. The substrate metallization significantly affected the TTF for the electromigration behavior of the Sn-58Bi solder joints. The substrate metallizations for electromigration performance of the Sn-58Bi solder are ranked in the following order: OSP-Cu, ENEPIG, and ENIG. Due to the polarity effect, current stressing enhanced the fast growth of intermetallic compounds (IMCs) at the anode interface. Cracks occurred at the Ni3Sn4 + Ni3P IMC/Cu interfaces on the cathode sides in the Sn-58Bi/ENIG joint and the Sn-58Bi/ENEPIG joint; this was caused by the complete consumption of the Ni(P) layer. Alternatively, failure occurred via deformation of the bulk solder in the Sn-58Bi/OSP-Cu joint. The experimental results confirmed that the electromigration reliability of the Sn-58Bi/OSP-Cu joint was superior to those of the Sn-58Bi/ENIG or Sn-58Bi/ENEPIG joints. 相似文献