Synthesis Mechanism of ZrB2@A12O3-Y2O3 Composite Powders with Core-Shell Microstructure

2016 ◽  
Vol 680 ◽  
pp. 133-136 ◽  
Author(s):  
Jie Guang Song ◽  
Da Ming Du ◽  
Fang Wang ◽  
Ming Han Xu ◽  
Shi Bin Li ◽  
...  
Keyword(s):  
High Temperature ◽  
Sintering Temperature ◽  
Precipitation Method ◽  
Core Shell ◽  
High Temperature Strength ◽  
Shell Microstructure ◽  
Composite Powders ◽  
Synthesis Mechanism ◽  
Co Precipitation ◽  
Shell Composite

ZrB2 has some excellent high-temperature performance. However, due to it is easily oxidized in the high-temperature air to impact high-temperature strength, which restricts its applied range. To decrease the oxidization and sintering temperature, and improve the strength of ZrB2 at high temperature, in this paper, the prepared composite powders is analyzed with XRD, SEM, EDS and TEM, which proves ZrB2@A12O3-Y2O3 core-shell composite powders are successfully synthesized by co-precipitation method, the synthesis mechanism of ZrB2@A12O3-Y2O3 core-shell composite powders is received through the results discussion.

THERMODYNAMIC AND KINETIC ANALYSES OF SYNTHESIZING ZrB2@Al(OH)3–Y(OH)3 CORE–SHELL COMPOSITE PARTICLES

2007 ◽  
Vol 14 (01) ◽  
pp. 117-122 ◽  
Author(s):  
JIEGUANG SONG ◽  
LIANMENG ZHANG ◽  
JUNGUO LI ◽  
JIANRONG SONG
Keyword(s):  
High Temperature ◽  
High Performance ◽  
Solubility Product ◽  
Ceramic Materials ◽  
Precipitation Method ◽  
Composite Particles ◽  
Core Shell ◽  
High Temperature Strength ◽  
Co Precipitation ◽  
Shell Composite

ZrB 2 has some excellent performances, but it is easily oxidized at high temperatures to impact the high-temperature strength, which restricts its applied range. To protect from the oxidization and improve the strength of ZrB 2 at high temperature, the surface of ZrB 2 particles is coated with the Al ( OH )3– Y ( OH )3 shell to synthesize ZrB 2@ Al ( OH )3– Y ( OH )3 core–shell composite particles. Through the thermodynamic and kinetic analyses of the heterogeneous nucleation and homogeneous nucleation, the concentration product of precursor ion ( Y 3+ or Al 3+) and OH - (Qi) must be greater than the solubility product (K sp ), respectively; the conditions of Y 3+ and Al 3+ are reached to produce Al ( OH )3– Y ( OH )3 shell on the ZrB 2 surface between the Y 3+ line and the AlO 2- line. Through TEM and XRD analyses, ZrB 2@ Al ( OH )3– Y ( OH )3 core–shell composite particles are successfully synthesized by the co-precipitation method, the shell layer quality is better at pH = 9, which established the foundation for preparing high-performance YAG / ZrB 2 and Al 2 O 3– YAG / ZrB 2 multiphase ceramic materials.

SYNTHESIS AND CHARACTERIZATION OF Si3N4@Al(OH)3–Y(OH)3 CORE-SHELL COMPOSITE PARTIC3LES

2008 ◽  
Vol 15 (05) ◽  
pp. 581-585 ◽  
Author(s):  
JIE-GUANG SONG ◽  
GANG-CHANG JI ◽  
SHI-BIN LI ◽  
LIAN-MENG ZHANG
Keyword(s):  
High Temperature ◽  
High Performance ◽  
Ceramic Materials ◽  
Composite Particles ◽  
Core Shell ◽  
High Temperature Strength ◽  
Bet Analysis ◽  
Co Precipitation ◽  
Shell Composite

Silicon nitride ( Si 3 N 4) has attracted substantial interest because of its extreme chemical and physical properties, but the sintering densification of Si 3 N 4 is difficult, and it is easily oxidized in the high-temperature air to impact high-temperature strength, which restricts its applied range. In order to decrease the oxidization and improve the strength of Si 3 N 4 at high temperature, the surface of Si 3 N 4 is coated with Al ( OH )3 and Y ( OH )3 to synthesis Si 3 N 4@ Al ( OH )3– Y ( OH )3 core-shell composite particles. Through TEM, XRD, and BET analysis, when pH is about 9, Si 3 N 4@ Al ( OH )3– Y ( OH )3 core-shell composite particles are successfully synthesized by co-precipitation methods. Coating layer is about 200 nm, which is compaction and conformability. Dispersion of coated Si 3 N 4 with Al ( OH )3 and Y ( OH )3 particles are very good. Synthesis of Si 3 N 4@ Al ( OH )3– Y ( OH )3 core-shell composite powder will lay the foundation for preparing high-performance YAG/Si 3 N 4 multiphase ceramic materials.

Fabrication and Oxidation-Resistance Property of Coated ZrB2-YAG-Al2O3 Multi-Phase Ceramics

2013 ◽  
Vol 544 ◽  
pp. 347-350
Author(s):  
Jie Guang Song ◽  
Fang Wang ◽  
Ming Han Xu ◽  
Shi Bin Li ◽  
Gang Chang Ji
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
Protective Layer ◽  
Zirconium Diboride ◽  
Oxidation Temperature ◽  
Al2o3 Content ◽  
Precipitation Method ◽  
Composite Powders ◽  
Co Precipitation ◽  
Multi Phase

Zirconium diboride is widely applied because of some excellent performances. The results show the A1(OH)3-Y(OH)3/ZrB2 composite powders is prepared by a co-precipitation method, the shell-core structure A12O3-Y2O3/ZrB2 composite powders is prepared by sintering A1(OH)3-Y(OH)3/ZrB2 composite powders. The coating and density ZrB2-YAG-Al2O3 multi-phase ceramics is sintered at 1700°C, 20MPa for 4min by using Al2O3-Y2O3-80wt%ZrB2 composite powders, the oxidation weight is increased with increasing the oxidation temperature, however, the oxidation weight is decreased with increasing the YAG-Al2O3 content. ZrB2 reacted with O2 to form B2O3, and B2O3 is reacted with Al2O3 to form Al18B4O33, which is melted and coated on the surface of ceramics to form a protective layer for the oxidation resistance of ceramics at high temperature.

Synthesis Mechanism and Microstructure Characterization of BaIn2O4

2011 ◽  
Vol 347-353 ◽  
pp. 1342-1347 ◽  
Author(s):  
Ping Ren ◽  
Li Cheng Zhou ◽  
Jun Xi Zhang ◽  
Hong Yun
Keyword(s):  
Sintering Temperature ◽  
Precipitation Method ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Synthesis Mechanism ◽  
X Ray ◽  
Grain Sizes ◽  
Co Precipitation

The synthesis mechanism and microstructures of BaIn2O4 particles were analyzed by simultaneous thermogravimetry - differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), and scanning electron microscope (SEM). Firstly, In(OH)3 and BaCO3 precursors were prepared by the co-precipitation method. Next, during the sintering process In(OH)3 initially decomposed into In2O3 and water, and then BaCO3 reacted with In2O3 to synthesize Ba4In6O13. Finally, Ba4In6O13 and In2O3 further reacted to form BaIn2O4. The obtained BaIn2O4 particles were in monoclinic structure and exhibited high crystal quality. The grains were tightly bound together and their boundaries became blurry. The grain sizes increased with increasing the sintering temperature.

Electron Microscopy of Silicon Nitride-Based Ceramics

1991 ◽  
Vol 49 ◽  
pp. 926-927
Author(s):  
Gareth Thomas
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Silicon Nitride ◽  
World Wide ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
High Temperature Strength ◽  
Sintering Additives ◽  
Glass Forming ◽  
Dense Product

Silicon nitride and silicon nitride based-ceramics are now well known for their potential as hightemperature structural materials, e.g. in engines. However, as is the case for many ceramics, in order to produce a dense product, sintering additives are utilized which allow liquid-phase sintering to occur; but upon cooling from the sintering temperature residual intergranular phases are formed which can be deleterious to high-temperature strength and oxidation resistance, especially if these phases are nonviscous glasses. Many oxide sintering additives have been utilized in processing attempts world-wide to produce dense creep resistant components using Si3N4 but the problem of controlling intergranular phases requires an understanding of the glass forming and subsequent glass-crystalline transformations that can occur at the grain boundaries.

scholarly journals Structure, Luminescence, and Magnetic Properties of Crystalline Manganese Tungstate Doped with Rare Earth Ion

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3717
Author(s):  
Jae-Young Jung ◽  
Soung-Soo Yi ◽  
Dong-Hyun Hwang ◽  
Chang-Sik Son
Keyword(s):  
Magnetic Field ◽  
Rare Earth ◽  
Sintering Temperature ◽  
Luminescent Properties ◽  
Concentration Quenching ◽  
Rare Earth Ions ◽  
Precipitation Method ◽  
Rare Earth Ion ◽  
Co Precipitation ◽  
Quenching Phenomenon

The precursor prepared by co-precipitation method was sintered at various temperatures to synthesize crystalline manganese tungstate (MnWO4). Sintered MnWO4 showed the best crystallinity at a sintering temperature of 800 °C. Rare earth ion (Dysprosium; Dy3+) was added when preparing the precursor to enhance the magnetic and luminescent properties of crystalline MnWO4 based on these sintering temperature conditions. As the amount of rare earth ions was changed, the magnetic and luminescent characteristics were enhanced; however, after 0.1 mol.%, the luminescent characteristics decreased due to the concentration quenching phenomenon. In addition, a composite was prepared by mixing MnWO4 powder, with enhanced magnetism and luminescence properties due to the addition of dysprosium, with epoxy. To one of the two prepared composites a magnetic field was applied to induce alignment of the MnWO4 particles. Aligned particles showed stronger luminescence than the composite sample prepared with unsorted particles. As a result of this, it was suggested that it can be used as phosphor and a photosensitizer by utilizing the magnetic and luminescent properties of the synthesized MnWO4 powder with the addition of rare earth ions.

scholarly journals Effect of Sintering Temperature on the Microstructure, Electrical and Magnetotransport Properties of La0.67Sr0.33MnO3 Compound

2014 ◽  
Vol 895 ◽  
pp. 319-322
Author(s):  
Lim Kean Pah ◽  
Abdul Halim Shaari ◽  
Chen Soo Kien ◽  
Chin Hui Wei ◽  
Albert Gan ◽  
...  
Keyword(s):  
Grain Size ◽  
Single Phase ◽  
Sintering Temperature ◽  
Measurement Range ◽  
Hexagonal Structure ◽  
Precipitation Method ◽  
Metal Insulator ◽  
Higher Temperature ◽  
Co Precipitation ◽  
Grain Surface

In this work, we report the effect of sintering temperature (900°C, 1000°C, 1100°C and 1200°C) on the electrical and magnetotransport properties of polycrystalline La0.67Sr0.33MnO3 (LSMO). Single phase of LSMO hexagonal structure (R-3c) accompanied with minor phases was successfully synthesized by co-precipitation method. With increasing sintering temperature, grain growth was promoted and grain connectivity was improved. It was found that an enhancement of resistivity on smaller grain size was due to larger grain surface over volume (grain boundaries effect). The shifting of the metal-insulator transition (TMI) to higher temperature was also responsible for observed changes in physical properties. TMI of 900°C, 1000°C and 1100°C were 232 K, 278 K and 298 K respectively however 1200°C was out of measurement range (higher than 300 K). In summary, CP900 with smaller grain size distribution (~200 nm) displayed the highest resistivity and MR% of -19.2% (at 80 K, 10 kG).

Synthesis of the high temperature superconductor YBa2Cu3O7−δ by the hydroxide co-precipitation method

1997 ◽  
Vol 278 (1-2) ◽  
pp. 55-61 ◽  
Author(s):  
I. Schildermans ◽  
M. Van Bael ◽  
E. Knaepen ◽  
J. Yperman ◽  
J. Mullens ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperature Superconductor ◽  
Precipitation Method ◽  
Co Precipitation

PREPARING DOUBLE-BASE THERMO-SENSITIVE CERAMICS WITH NANOPOWDERS

2006 ◽  
Vol 05 (02n03) ◽  
pp. 265-271
Author(s):  
MENG KUI WANG ◽  
YU QIANG YANG
Keyword(s):  
Ceramic Material ◽  
Thick Film ◽  
Production Cost ◽  
Sintering Temperature ◽  
Precipitation Method ◽  
Sensitive Material ◽  
Surface Active Agents ◽  
Surface Active ◽  
Co Precipitation ◽  
Double Base

The preparing process and the properties of thick-film double-based thermo-sensitive material were studied. The preparing steps were as follows: (i) preparing Ba 1-x Sr x TiO 3 micro-powders with chemical co-precipitation method; (ii) adding dispersants and surface active agents into crushing medium powders to prepare Ba 1-x Sr x TiO 3 nanopowders; (iii) preparing V 2 O 3-based micro-powders; (iv) mixing Ba 1-x Sr x TiO 3 nanopowders, V 2 O 3-based micro-powders, donor impurities, acceptor impurities and micro additives according to a certain ratio to make thick-film thermo-sensitive ceramic material. The presintering and sintering temperature of the prepared PTC ceramics were both reduced, which is very meaningful in using cheaper SiC instead of more expensive MoSi 2, prolonging the kiln's life, and lowering the production cost. The samples we prepared did not contain PbO , so they are safe to the environment.

INFLUENCE OF SYNTHESIS CONDITIONS ON Al(OH)3–Y(OH)3/ZrB2 COMPOSITE PARTICLES

2007 ◽  
Vol 14 (06) ◽  
pp. 1135-1141 ◽  
Author(s):  
JIE-GUANG SONG ◽  
LIAN-MENG ZHANG ◽  
JUN-GUO LI ◽  
JIAN-RONG SONG
Keyword(s):  
High Temperature ◽  
Reaction Time ◽  
Precipitation Method ◽  
Composite Particles ◽  
Coating Quality ◽  
Ultrasonic Dispersion ◽  
High Temperature Properties ◽  
Synthesis Conditions ◽  
Solution Reaction ◽  
Co Precipitation

Although Zirconium diboride ( ZrB 2) is a desirable combination with some good properties, it is easily oxidized in the high-temperature air to impact high-temperature properties, which dwindles the applied range. In order to decrease oxidization and improve the high-temperature properties of ZrB 2, the surface of ZrB 2 is coated with Al ( OH )3– Y ( OH )3 to synthesize Al ( OH )3– Y ( OH )3/ ZrB 2 composite particles. In this paper, the conditions of synthesizing Al ( OH )3– Y ( OH )3/ ZrB 2 composite particles by the co-precipitation method are investigated. Al ( OH )3– Y ( OH )3/ ZrB 2 composite particles are synthesized under different conditions, but the conditions of synthesizing Al ( OH )3– Y ( OH )3/ ZrB 2 composite particles with the better coating quality require pH = 9, the appropriate concentration ( Al 3+ = 0.017 mol/L , Y 3+ = 0.01 mol/L ) of composite solution, reaction time of 60 min, titration speed of 0.05 ml/s, using the dispersant in the ZrB 2 suspension and the ultrasonic dispersion, respectively.

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