Drying Behavior of Sol-Gel Derived A12O3 and Al2O3-Sic Composites

1986 ◽  
Vol 73 ◽  
Author(s):  
R. H. Krabill ◽  
D. E. Clark
Keyword(s):  
Sol Gel ◽  
Drying Process ◽  
Critical Step ◽  
Drying Behavior ◽  
Sic Composites ◽  
Sol Gel Synthesis ◽  
Gel Drying

ABSTRACTGel drying is a critical step in the sol-gel synthesis of Al2O3 and Al2O3-SiC composites. Problems exist during the drying stage that affect the monolithic properties of the sintered products. Classical drying theory was applied to the drying behavior of Al2O3 and Al2O3-SiC composites in an effort to optimize the drying process and understand the controlling mechanisms.

Electrophoretic Deposition of Mullite Based Oxygen Diffusion Systems on C/C-Si-SiC Composites

2006 ◽  
Vol 314 ◽  
pp. 201-206 ◽  
Author(s):  
Tanja Damjanović ◽  
Christos Argirusis ◽  
B. Jokanović ◽  
Günter Borchardt ◽  
Kirsten Moritz ◽  
...  
Keyword(s):  
Electrophoretic Deposition ◽  
Oxygen Diffusion ◽  
Sol Gel ◽  
Time Intervals ◽  
Al2o3 Powder ◽  
Additional Layer ◽  
Diffusion Systems ◽  
Sic Composites ◽  
Sol Gel Synthesis ◽  
Reference Samples

Combining sol-gel synthesis of 3/2 mullite through hydrolysis and condensation of tetraethoxysilane and aluminum-tri-sec-butylate with electrophoretic deposition (EPD) yields sufficiently thick and homogeneous layers which transform into mullite at T ≥ 1000 °C. The characterisation of the mullite precursor during synthesis was performed through electroacustic measurements. The protectiveness of the deposited mullite layers was tested in air in the temperature range 1200 °C ≤ T ≤ 1550 °C by means of isothermal thermogravimetric analysis for up to 200 hours. Comparing the oxidation rate of mullite coated C/C-Si-SiC samples to that of uncoated reference samples clearly demonstrated that mullite offers a significant improvement to the oxidation resistance of the uncoated material. At temperatures above 1600 °C the protectiveness of the deposited layer is reduced due to the existence of a liquid phase and the formation of CO bubbles above the cracks in the SiC layer. In order to prolong the protectiveness of our mullite layers at higher temperatures we deposited an additional layer from a suspension of mullite precursor with 5 wt. % of Al2O3 powder. The protectiveness of so obtained mullite and mullite/ Al2O3 layers was also tested under cyclic conditions at 1500 °C and 1550 °C. These experiments clearly demonstrated that all samples withstood at least for 4-10 cycles which were performed subsequently in different time intervals (from 2-3 days to 1 h).

scholarly journals Aerogels: II. Applications in catalysis

2002 ◽  
Vol 56 (12) ◽  
pp. 514-520
Author(s):  
Aleksandar Orlovic ◽  
Djordje Janackovic ◽  
Ljiljana Kostic-Gvozdenovic ◽  
Dejan Skala
Keyword(s):  
Molecular Level ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Structural Features ◽  
Metastable Phases ◽  
Drying Process ◽  
Sol Gel Process ◽  
One Step ◽  
Sol Gel Synthesis

Sol-gel synthesis, and the resulting materials (xerogels and aerogels) are finding increasing application in the synthesis of catalysts, due to their unique characteristics. The most important features of the sol-gel process are: the ability to achieve homogeneity at the molecular level, the introduction of several species in only one step and the ability to stabilize metastable phases. The supercritical drying process produces aerogels with structural features quite different to conventional materials. Some of these characteristics of aerogels can make them very effective catalysts.

Inorganic-organic Hybrid Materials for Real 3-D Sub-νm Lithography

2003 ◽  
Vol 780 ◽  
Author(s):  
R. Houbertz ◽  
J. Schulz ◽  
L. Fröhlich ◽  
G. Domann ◽  
M. Popall ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Sol Gel ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Hybrid Polymer ◽  
Organic Hybrid ◽  
Two Photon ◽  
Applied Technology ◽  
Scale Structures ◽  
Sol Gel Synthesis

AbstractReal 3-D sub-νm lithography was performed with two-photon polymerization (2PP) using inorganic-organic hybrid polymer (ORMOCER®) resins. The hybrid polymers were synthesized by hydrolysis/polycondensation reactions (modified sol-gel synthesis) which allows one to tailor their material properties towards the respective applications, i.e., dielectrics, optics or passivation. Due to their photosensitive organic functionalities, ORMOCER®s can be patterned by conventional photo-lithography as well as by femtosecond laser pulses at 780 nm. This results in polymerized (solid) structures where the non-polymerized parts can be removed by conventional developers.ORMOCER® structures as small as 200 nm or even below were generated by 2PP of the resins using femtosecond laser pulses. It is demonstrated that ORMOCER®s have the potential to be used in components or devices built up by nm-scale structures such as, e.g., photonic crystals. Aspects of the materials in conjunction to the applied technology are discussed.

Sol-Gel Synthesis, Structure and Optical Properties of Nickel-Manganese Ferrites

2019 ◽  
Vol 11 (3) ◽  
pp. 03021-1-03021-5
Author(s):  
V. S. Bushkova ◽  
◽  
I. P. Yaremiy ◽  
B. K. Ostafiychuk ◽  
N. I. Riznychuk ◽  
...  
Keyword(s):  
Optical Properties ◽  
Sol Gel ◽  
Sol Gel Synthesis ◽  
Nickel Manganese

Sol-Gel Synthesis of Nano-Scale, End-Member Albite Feldspar (NaAlSi3O8)

2021 ◽  
Author(s):  
L.M. Anovitz ◽  
A. Affolter ◽  
M.C. Cheshire ◽  
A.J. Rondinone ◽  
Lawrence F. Allard
Keyword(s):  
Sol Gel ◽  
Nano Scale ◽  
Sol Gel Synthesis

scholarly journals Aqueous Sol-Gel Synthesis of Different Iron Ferrites: From 3D to 2D

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1554
Author(s):  
Justinas Januskevicius ◽  
Zivile Stankeviciute ◽  
Dalis Baltrunas ◽  
Kęstutis Mažeika ◽  
Aldona Beganskiene ◽  
...  
Keyword(s):  
Magnetic Measurements ◽  
Substrate Surface ◽  
Sol Gel ◽  
Synthesis Method ◽  
Xrd Analysis ◽  
Dip Coating ◽  
Yttrium Iron ◽  
Iron Garnet ◽  
Dip Coating Technique ◽  
Sol Gel Synthesis

In this study, an aqueous sol-gel synthesis method and subsequent dip-coating technique were applied for the preparation of yttrium iron garnet (YIG), yttrium iron perovskite (YIP), and terbium iron perovskite (TIP) bulk and thin films. The monophasic highly crystalline different iron ferrite powders have been synthesized using this simple aqueous sol-gel process displaying the suitability of the method. In the next step, the same sol-gel solution was used for the fabrication of coatings on monocrystalline silicon (100) using a dip-coating procedure. This resulted, likely due to substrate surface influence, in all coatings having mixed phases of both garnet and perovskite. Thermogravimetric (TG) analysis of the precursor gels was carried out. All the samples were investigated by X-ray powder diffraction (XRD) analysis. The coatings were also investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM) and Mössbauer spectroscopy. Magnetic measurements were also carried out.

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