Preparation and Characterization of Fused Silica Micro-Powders and Ceramics

2011 ◽  
Vol 412 ◽  
pp. 129-132 ◽  
Author(s):  
Jin Ye Niu ◽  
Zhi Wei Chen ◽  
Liu Feng ◽  
Zheng Min Li ◽  
Min Tan
Keyword(s):  
Particle Size ◽  
Thermal Expansion ◽  
Lactic Acid ◽  
Milling Time ◽  
Bending Strength ◽  
Slip Casting ◽  
Volume Density ◽  
Fused Silica ◽  
Lactic Acid Content

Fused silica micro-powders with D50of 1.8μm were firstly prepared by ball milling. Effects of milling time on particle size distribution and microstructures of the powders were discussed. Then, the green compacts with volume density of 1.86g/cm3was obtained by slip casting with lactic acid as dispersant. Effects of lactic acid content on apparent viscosity of the slurry, thickness and density of the green compacts were investigated. Finally, fused silica ceramics with thermal expansion coefficient of 0.56∙10-6/°C, bending strength of 64MPa and volume density of 1.94g/cm3were prepared.

Effect of Process on the Dielectric Properties of BaTiO3-Based X9R Ceramics

2014 ◽  
Vol 906 ◽  
pp. 18-24 ◽  
Author(s):  
Bao Lin Zhang ◽  
Bin Bin Zhang ◽  
Ning Ning Wang ◽  
Jing Ming Fei
Keyword(s):  
Particle Size ◽  
Dielectric Properties ◽  
Milling Time ◽  
Sintering Temperature ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
Sintered Ceramic ◽  
X Ray ◽  
Particle Size Analyzer

The effect of milling time and sintering process on the dielectric properties of BaTiO3-based X9R ceramics was investigated. The characterization of the raw powders and the sintered ceramic was carried out by X-ray diffraction and scanning electron microscopy. The particle size distribution of the mixed powders was examined by Laser Particle Size Analyzer. The results shown that with the milling time extended, the Cruie Peak was depressed, or even disappeared. Moreover, with the rise of sintering temperature, the dielectric constant of the ceramics increased and the dielectric loss decreased gradually. Eventually, by milling for 11h and sintering at 1090°Cfor 2h, good dielectric properties were obtained, which were ε25°C≥ 2526, εr/εr25°C≤± 12% (–55~200°C), tanδ≤1.12% (25°C).

The Effect of Milling Time on Physical Properties, Magnetic Properties and Microstructure of Bonded Magnet BaFe12O19

2020 ◽  
Vol 855 ◽  
pp. 34-39
Author(s):  
Suprapedi ◽  
Muljadi ◽  
Priyo Sardjono ◽  
Ramlan Ramlan
Keyword(s):  
Particle Size ◽  
Magnetic Properties ◽  
Particle Size Distribution ◽  
Physical Properties ◽  
Bulk Density ◽  
Ball Mill ◽  
Milling Time ◽  
Mixed Powder ◽  
Bonded Magnet

A bonded permanent magnet of Barium hexa Ferrite has been made using powder BaFe12O19 (commercial ferrite) and a polymer of bakelite powder as binder. The composition of bakelite was varried 5% wt. The preparation of sample was begun with mass weighing for each material, then mixed together using ball mill for 1, 6 and 12 hours and using aquades as milling media. The mixed powder is dried in an oven at 110 °C for 4 hours, then the particle size distribution was measured. After that, the dried sample powder was pressed to form a pellet at pressure 40 MPa and temperature about 160 °C for 20 minutes. The characterization of sample pellet was done such as measurement of bulk density, hardness , magnetic properties using VSM and anylisis of microstructure using SEM. The results of the characterization show that the density and magnetic properties tend to increase with increasing of milling time, where the highest density, hardness and highest magnetic properties are achieved at sample with milling time for 12 hours. The value of magnetic properties at this condition are flux magnetic of 530 Gauss, remenance of 3100 Gauss, coercivity of 1,10 kOe.

Thermal and Structural Characterization of Nanocomposite Iron Nitride - Alumina and Iron Nitride - Silica Particles

2001 ◽  
Vol 703 ◽  
Author(s):  
Ann M. Viano ◽  
Sanjay R. Mishra
Keyword(s):  
Particle Size ◽  
Milling Time ◽  
Iron Nitride ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Peak ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
The One

ABSTRACTNanocomposite iron nitride based powders are known to have enhanced magnetic and other physical properties. To further explore their potential for application in various fields, we have performed a systematic study of the iron nitride - alumina and iron nitride - silica systems. Iron nitride powder of composition FexN (2 < x < 4), containing both Fe3N and Fe4N phases, was mechanically milled with Al2O3 or SiO2 powder for 4, 8, 16, 32, and 64 hours at the following compositions; (FexN)0.2(Al2O3)0.8, (FexN)0.6(Al2O3)0.4, (FexN)0.2(SiO2)0.8, and (FexN)0.6(SiO2)0.4. Differential thermal analysis and X-ray diffraction were performed to investigate thermal and structural transitions as a function of milling time. As the milling time is increased, the thermal peak corresponding to Fe4N is diminished, while the one corresponding to Fe3N is enhanced. These transitions are correlated with X-ray diffraction patterns. All XRD peaks broaden as a function of milling time, corresponding to smaller particle size. Transmission electron microscopy also reveals a decrease in particle size as the milling time in increased.

Preparation and Characterization of Nb2O5-Al2O3 System Ceramics with Different Al2O3 Additions

2013 ◽  
Vol 544 ◽  
pp. 60-63 ◽  
Author(s):  
Xiao Zhen Zhang ◽  
Jian Er Zhou ◽  
Yu Hua Jiang ◽  
Chun Rong Wu ◽  
Chuan Ying Lin
Keyword(s):  
Thermal Expansion ◽  
Phase Composition ◽  
Binary System ◽  
Monoclinic Phase ◽  
Bending Strength ◽  
Raw Materials ◽  
Reaction Sintering ◽  
Strength Measurement ◽  
Low Thermal Expansion

The Nb2O5-Al2O3 binary system ceramics were prepared by high temperature solid state reaction sintering, using Nb2O5 and Al2O3 micro powder as the raw materials. The samples were characterized by XRD, SEM, thermodilatometric analysis and mechanical strength measurement. The influences of Al2O3 content on the phase composition, microstructure, thermal expansion properties and bending strength were investigated. Results show the samples shows obvious changes in phase composition and microstructure with the addition of Al2O3 from 2.5% to 15%. The pure Nb2O5 ceramic is composed of monoclinic phase Nb2O5, while different monoclinic aluminum niobates were formed with different Al2O3 additions. Obvious microcracking can be observed for the samples without and with 2.5% and 7.5% Al2O3 additions. The addition of Al2O3 leads to significant increase of bending strength, and all the samples keep relatively low thermal expansion coefficient (TEC). The Nb2O5-Al2O3 binary system ceramics with ultra low TEC (0.55~0.86×10-6°C-1) and improved bending strength (50.4~70.6MPa) could be obtained with the addition of 7.5~15% Al2O3 when sintered at 1390°C for 2h.

Properties of Silica Ceramic Made from Amorphous Silica

2010 ◽  
Vol 434-435 ◽  
pp. 838-839 ◽  
Author(s):  
Cai Fen Wang ◽  
Jia Chen Liu ◽  
Ji Ping Guo ◽  
Di Song ◽  
Wen Jun Lian
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Amorphous Silica ◽  
Glassy Phase ◽  
Bending Strength ◽  
Coal Fly Ash ◽  
Slip Casting ◽  
Fused Silica ◽  
Casting Method ◽  
Silica Ceramic

The mixture of amorphous silica extracted from coal fly ash and fused silica was used to prepare density silica ceramic through slip-casting method. The XRD results showed that a large amount of cristobalite was formed at 1300°C which can weaken mechanical properties. The SEM results showed that glassy phase present from fused silica promoted ceramic densification. According to the experiment results, it was found that the bending strength was highest when mixing 65wt% fused silica and sintering at 1200°C for 4 hours.

scholarly journals Effects of polymorphic form and particle size of SiO2 fillers on the properties of SiO2–PEEK composites

2021 ◽  
Vol 11 (04) ◽  
pp. 2150021
Author(s):  
Peng Jie Xue ◽  
Shi Lin Liu ◽  
Jian Jiang Bian
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Thermal Expansion ◽  
Dielectric Loss ◽  
Mechanical Strength ◽  
Polymorphic Form ◽  
Fused Silica ◽  
High Frequencies ◽  
Silica Fillers ◽  
Filled Composite

The effects of polymorphic form and particle size of SiO2 fillers on the dielectric, mechanical and thermal properties of SiO2–Polyetheretherketone (SiO2–PEEK) composites were investigated in this paper. Strong low frequency (<10Hz) Debye-like dielectric dispersions could be observed for all samples. The dielectric permittivity at high frequencies of the composite exhibits little morphology or particle size-sensitive characteristics of the SiO2 fillers. All the composites obtained in this case demonstrate the dielectric permittivities of [Formula: see text] at high frequencies. The crystalline [Formula: see text]-cristobalite filled composite exhibits lower dielectric loss and mechanical strength, but larger thermal expansion coefficient and thermal conductivity, compared with the similar particle sized amorphous SiO2 filled one. The crystalline [Formula: see text]-quartz filled composite demonstrates the lowest mechanical strength and highest dielectric loss. An increase in particle size of the spherical fused silica fillers decreases the dielectric loss, while increases the thermal conductivity of the composite. The flexural strength of the composite reaches the maximum value of 113 MPa when the particle size of spherical SiO2 filler is [Formula: see text]m. Particle packing by combining optimal amounts of differently sized spherical fused silica fillers leads to a substantial improvement of mechanical strength (153MPa) coupled with reasonable dielectric and thermal properties due to the synergic effect (dielectric permittivity ([Formula: see text] = 3.35, dielectric loss (tan[Formula: see text] @10 GHz, thermal conductivity ([Formula: see text] = 0.74 W/m*k ([Formula: see text]C), coefficient of thermal expansion ([Formula: see text]C and relative density ([Formula: see text]) = 99.72%).

Synthesis and Characterization of Copper/Paraffin Nanocomposites for Thermal Actuation

2011 ◽  
Vol 55-57 ◽  
pp. 1764-1768
Author(s):  
Bin Xu ◽  
Bai Yang Lou
Keyword(s):  
Particle Size ◽  
Milling Time ◽  
Thermal Sensitivity ◽  
High Energy ◽  
Transmission Electron ◽  
Thermal Actuation ◽  
Energy Ball ◽  
Thermoforming Process ◽  
Particle Size And Shape

The copper/paraffin nanocomposites were synthesized by high energy ball milling. Observation of the microstructure, comparison and ascertainment of the particle size of the composite were analyzed by transmission electron microscope. Then the composite was put into a home-made copper tube (5 mm in diameter, 20 mm in length, closed at one end) by thermoforming process, and its thermal sensitivity was measured using thermo-controlled optical micro measuring equipment. The effects of milling time on the microstructures and the thermal sensitivity of copper/paraffin nanocomposites were investigated. The results showed that different milling time caused the changes in particle size and shape of the composite, and had a significant effect on its thermal sensitivity. With increasing milling time, the thermal sensitivity of composite gradually increased.

Microstructural and Microchemical Characterization of Nickel Sulfide Inclusions in Plate Glass

1991 ◽  
Vol 49 ◽  
pp. 962-963
Author(s):  
J. Cooper ◽  
O. Popoola ◽  
W. M. Kriven
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Glass Matrix ◽  
Nickel Sulfide ◽  
Plate Glass ◽  
Thermal Expansion Mismatch ◽  
Volume Increase ◽  
Β Phase ◽  
Microchemical Characterization

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.

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