Structure and Properties of Ceramic Fibers Prepared From Polymeric Precursors [1]

1986 ◽  
Vol 73 ◽  
Author(s):  
J. Lipowitz ◽  
H. A. Freeman ◽  
H. A. Goldberg ◽  
R. T. Chen ◽  
E. R. Prack
Keyword(s):  
High Purity ◽  
Structure And Properties ◽  
Ceramic Fibers ◽  
Chemical Methods ◽  
Polymeric Precursors ◽  
Conventional Methods ◽  
Lower Temperature ◽  
Organosilicon Polymers

ABSTRACTCeramics can be prepared by pyrolysis of organosilicon polymers. Advantages of this method of ceramics preparation are; the ability to prepare shapes difficult to achieve by other methods such as fibers and films; the ability to achieve high purity because reagents used to prepare the polymer can be purified by well established chemical methods; processing at lower temperature than conventional methods [2].

CERAMICS BASED ON ORGANOSILICON POLYMERS-PRECURSORS: MICROSTRUCTURE AND PROPERTIES (review). Part 1

2021 ◽  
pp. 21-33
Author(s):  
A.M. Shestakov ◽  
Keyword(s):  
Ceramic Composite ◽  
Porous Ceramic ◽  
Ceramic Materials ◽  
Structure And Properties ◽  
Ceramic Foams ◽  
Controlled Porosity ◽  
Composition Structure ◽  
Silicon Based ◽  
Porous Ceramic Materials ◽  
Organosilicon Polymers

The paper considers the process of pyrolysis of polymers-precursors, and also shows the influence of various parameters of technological processes for obtaining ceramics on its composition, structure, and properties. The main types of binary, ternary and multicomponent silicon-based ceramics, methods of its preparation, features of structure and properties are considered, and promising directions of application of ceramics are determined. The possibility of obtaining porous ceramic materials (ceramic foams) with controlled porosity and ceramic composite materials with a given composition is noted.

Preparation of Mullite Powder by Aluminum Sulfate and Silica in Molten Sodium Sulfate

2007 ◽  
Vol 336-338 ◽  
pp. 924-926 ◽  
Author(s):  
Bo Quan Zhu ◽  
Xue Dong Li ◽  
Rui Hao ◽  
Hou Zhi Wang
Keyword(s):  
Phase Composition ◽  
High Purity ◽  
Sodium Sulfate ◽  
Aluminum Sulfate ◽  
Synthetic Method ◽  
Mullite Formation ◽  
Whisker Crystal ◽  
Molten Sodium ◽  
Conventional Methods ◽  
Mullite Powder

Mullite powder was prepared through reaction of aluminum sulfate and silica in molten sodium sulfate media. The phase composition and microstructure of mullite powder were investigated. The results showed that high purity mullite is prepared by this method. The mullite powder exhibits needle-like whisker crystal with 50~100 nm in diameter and 3~8 #m in length. It is found that by this method mullite starts to form at 900oC, the quartz phase is disappeared about 1000oC, and mullite begin to decompose when the temperature is over 1100oC. Thus, the reasonable synthesizing temperature is about 1000oC. This synthetic method is characterized by process simplicity, the temperature of mullite formation is lower than 200-400oC compared with other conventional methods.

Effect of magnesium on structure and properties of LiNbO3 prepared from polymeric precursors

2002 ◽  
Vol 28 (3) ◽  
pp. 265-270 ◽  
Author(s):  
A.Z Simões ◽  
A.H.M González ◽  
A.A Cavalheiro ◽  
M.A Zaghete ◽  
B.D Stojanovic ◽  
...  
Keyword(s):  
Structure And Properties ◽  
Polymeric Precursors

scholarly journals Synthesis of Silicon Carbide Powders from Methyl-Modified Silica Aerogels

2020 ◽  
Vol 10 (18) ◽  
pp. 6161
Author(s):  
Kyoung-Jin Lee ◽  
Yanggu Kang ◽  
Young Hun Kim ◽  
Se Won Baek ◽  
Haejin Hwang
Keyword(s):  
Silicon Carbide ◽  
High Purity ◽  
Silica Aerogel ◽  
Carbothermal Reduction ◽  
Single Phase ◽  
Phase Evolution ◽  
Silica Aerogels ◽  
Methyl Groups ◽  
Modified Silica ◽  
Lower Temperature

β-silicon carbide (SiC) powders were synthesized by the carbothermal reduction of methyl-modified silica aerogel/carbon mixtures. The correlations between the phase evolution and morphologies of the SiC powders and the C/SiO2 ratio were investigated. At a C/SiO2 ratio of 3, β-SiC formed at 1425 °C and single-phase SiC powders were obtained at 1525 °C. The methyl groups (-CH3) on the silica aerogel surfaces played important roles in the formation of SiC during the carbothermal reduction. SiC could be synthesized from the silica aerogel/carbon mixtures under lower temperature and C/SiO2 ratios than those needed for quartz or hydrophilic silica. The morphology of the SiC powder depended on the C/SiO2 ratio. A low C/SiO2 ratio resulted in β-SiC powder with spherical morphology, while agglomerates consisting of fine SiC particles were obtained at the C/SiO2 ratio of 3. High-purity SiC powder (99.95%) could be obtained with C/SiO2 = 0.5 and 3 at 1525 °C for 5 h.

Polymeric Precursors for Bn and SiNCB Ceramic Fibers

2007 ◽  
pp. 103-112 ◽  
Author(s):  
Thomas Wideman ◽  
Edward E. Remsen ◽  
Gregg A. Zank ◽  
Larry G. Sneddon
Keyword(s):  
Ceramic Fibers ◽  
Polymeric Precursors

scholarly journals Facile Photochemical strategy for synthesis of high-performance amorphous MoS2 nanoparticles

2021 ◽  
Author(s):  
Haifeng Sun ◽  
Manlin Yang ◽  
Shan Pu ◽  
Lichen Gou ◽  
Caizhi Lv ◽  
...  
Keyword(s):  
High Purity ◽  
High Performance ◽  
Ambient Conditions ◽  
Chemical Methods ◽  
Mos2 Nanoparticles

It is difficult to avoid the formation of polysulfides by traditional chemical methods, and the synthesis of high purity amorphous MoS2 nanomaterials under ambient conditions is still a challenging task....

On the Sintering Activation Energy of α-Al2O3

2008 ◽  
Vol 368-372 ◽  
pp. 686-687 ◽  
Author(s):  
Wei Quan Shao ◽  
Shaou Chen ◽  
Da Li ◽  
Ping Qi ◽  
Yong Wan ◽  
...  
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Temperature Interval ◽  
High Purity ◽  
Powder Compact ◽  
Isothermal Condition ◽  
Particle Sizes ◽  
Higher Temperature ◽  
Lower Temperature ◽  
Increasing Temperature

The sintering activation energy of high-purity alumina powders with different particle sizes was evaluated under non-isothermal condition. It was found that, during sintering, the activation energy for the lower temperature stage is higher than that for higher temperature stage. The value of the activation energies for the powder compact with larger particle size was higher than that for the powder compact with smaller particle size. If the selected temperature interval for calculation was narrow enough, the evaluated activation energy values varied with the increasing temperature continuously.

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