Al2O3 Microspheres Prepared by Cathode Plasma Electrolysis

2017 ◽  
Vol 70 (1) ◽  
pp. 120 ◽  
Author(s):  
Chenxu Liu ◽  
Jin Zhang ◽  
Yedong He ◽  
Peng Wang ◽  
Shunjie Deng ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Surface Tension ◽  
High Temperature ◽  
Formation Mechanism ◽  
Room Temperature ◽  
Cathode Plasma ◽  
Plasma Electrolysis ◽  
High Concentrations ◽  
Α Al2o3 ◽  
High Temperature Calcination

Al2O3 microspheres were prepared by cathode plasma electrolysis (CPE) in an aqueous solution of Al(NO)3·9H2O. Compared with high-temperature calcination methods, the CPE method afforded the preparation of microspheres directly at room temperature. The results showed that regular microspheres formed under relatively high concentrations of Al(NO)3·9H2O. The microspheres, with diameters mostly in the range of 5–30 μm, consisted of γ-Al2O3 and α-Al2O3. The possible formation mechanism included the following processes: (1) Al(OH)3 intermediate was formed during the cathodic reactions; (2) plasma energized the intermediate to Al2O3; and (3) microspheres formed under the effect of the surface tension.

A high temperature, pressure study of the comparative rates of enolization and oxidation of acetone in aqueous solution

1986 ◽  
Vol 64 (11) ◽  
pp. 2235-2237 ◽  
Author(s):  
John W. Thomas ◽  
Jay E. Taylor
Keyword(s):  
Aqueous Solution ◽  
High Temperature ◽  
Partial Pressure ◽  
Oxygen Concentration ◽  
Total Pressure ◽  
Room Temperature ◽  
Isotopic Exchange ◽  
Partial Pressure Of Oxygen

The rate of enolization and acetone has been determined as 6.6 × 10−4 s−1 at 193.5 °C under nitrogen at 136 atm total pressure via isotopic exchange. The rate of oxidation was determined to be 8.8 × 10−6 s−1 at 193.5 °C in 123 atm partial pressure of oxygen (136 atm total pressure). In a previous study it was shown that the rates of oxidation of several ketones correlated with the extents of enolization at room temperature. This prompted the suggestion that the enol is an intermediate in the oxidation. Since the rate of enolization exceeded the rate of oxidation by a factor of 75, this suggestion is further supported. A dependence of the rate of oxidation of acetone on oxygen concentration was also demonstrated.

Lattice site and photoluminescence of erbium implanted in α–Al2O3

1997 ◽  
Vol 12 (5) ◽  
pp. 1401-1404 ◽  
Author(s):  
G. N. van den Hoven ◽  
A. Polman ◽  
E. Alves ◽  
M. F. da Silva ◽  
A. A. Melo ◽  
...  
Keyword(s):  
Room Temperature ◽  
Lattice Site ◽  
Low Dose ◽  
Photoluminescence Spectra ◽  
Ion Channeling ◽  
Octahedral Sites ◽  
Erbium Ions ◽  
High Concentrations ◽  
Α Al2o3 ◽  
Single Crystal Sapphire

Single-crystal sapphire (α–Al2O3) was implanted at room temperature with 200 keV erbium ions to a fluence of 8 × 1013 cm–2. Ion channeling using 1.6 MeV He+ shows that the crystal suffers little damage for this low dose implant. Angular scans through axial and planar directions in the crystal indicate that 70% of the Er atoms reside on displaced octahedral sites in the α–Al2O3 lattice. As pure Al2O3 has a high density of free octahedral sites, this explains why high concentrations of Er can be dissolved in this material. Smaller fractions of Er are found on tetrahedral (20%) and random (10%) sites. The samples exhibit strongly peaked photoluminescence spectra around 1.5 μm, due to intra-4f transitions in Er3+, indicating the existence of well-defined sites for the luminescing Er3+ ions. It is concluded that the octahedral site is the dominating optically active site in the lattice.

Effect of α-Al2O3 Micro Powder on Performance of Porous Plug Well Block

2011 ◽  
Vol 422 ◽  
pp. 561-565 ◽  
Author(s):  
Zhi Hui Li ◽  
Sen Wang ◽  
Jing Li ◽  
Feng Wu
Keyword(s):  
High Temperature ◽  
Flexural Strength ◽  
Bulk Density ◽  
Thermal Shock ◽  
Compression Strength ◽  
Room Temperature ◽  
Apparent Porosity ◽  
Raw Material ◽  
Porous Plug ◽  
Α Al2o3

In connection with broken-down mechanics of ladle porous plug well block，with tabular alundum、allitic spinel、industrial chrome oxide as the main raw material and aluminate cement and active α-Al2O3 micro powder as binder，we prepare 9 groups porous plug well block samples，for studying the species of α-Al2O3 micro powder and impact of its addition on the properties of samples．By testing room temperature flexural strength of samples、room temperature compression strength，flexural strength after sintering at 1600°C and heating for 3 hours、compression strength after burning，bulk density and apparent porosity before burning and after burning，thermal shock、high temperature bending strength and other performance indicators．The results show that，adding α-Al2O3 micro powder of multi-peak distribution in the samples，whoes granularity distributes reasonably，may have better effects of padding，and form more uniform intergranular spinel，at the same time，find that the higher the bonding strength between the grains，the higher pyknosis strength of samples，and the performance indicators are excellent．When the addition of α-Al2O3 micro powder of multi-peak distribution are 10%，compression strength of sample after burning is 132MPa，high temperature flexural strength is 14MPa，bulk density is 3.25g/cm3，and apparent porosity is 12%，also，thermal shock stability and other combination properties are the best．To meet the excellent performance that delivery needs and have higher safety factor，we may use corundum-spinel porous plug well block of longer lifespan bonding low cement．

ABOUT HEAT CAPACITY OF TITANIUM CARBIDE TiCx

2019 ◽  
pp. 56-66
Author(s):  
I. Khidirov ◽  
V. V. Getmanskiy ◽  
A. S. Parpiev ◽  
Sh. A. Makhmudov
Keyword(s):  
Heat Capacity ◽  
High Temperature ◽  
Titanium Carbide ◽  
Temperature Dependence ◽  
Carbon Concentration ◽  
Room Temperature ◽  
Thermodynamic Characteristics ◽  
Liquid Nitrogen Temperature ◽  
Analysis Data ◽  
Thermal Excitation

This work relates to the field of thermophysical parameters of refractory interstitial alloys. The isochoric heat capacity of cubic titanium carbide TiCx has been calculated within the Debye approximation in the carbon concentration  range x = 0.70–0.97 at room temperature (300 K) and at liquid nitrogen temperature (80 K) through the Debye temperature established on the basis of neutron diffraction analysis data. It has been found out that at room temperature with decrease of carbon concentration the heat capacity significantly increases from 29.40 J/mol·K to 34.20 J/mol·K, and at T = 80 K – from 3.08 J/mol·K to 8.20 J/mol·K. The work analyzes the literature data and gives the results of the evaluation of the high-temperature dependence of the heat capacity СV of the cubic titanium carbide TiC0.97 based on the data of neutron structural analysis. It has been proposed to amend in the Neumann–Kopp formula to describe the high-temperature dependence of the titanium carbide heat capacity. After the amendment, the Neumann–Kopp formula describes the results of well-known experiments on the high-temperature dependence of the heat capacity of the titanium carbide TiCx. The proposed formula takes into account the degree of thermal excitation (a quantized number) that increases in steps with increasing temperature.The results allow us to predict the thermodynamic characteristics of titanium carbide in the temperature range of 300–3000 K and can be useful for materials scientists.

Nanocomposite Polyurethane Foams Via POSS Blends

2002 ◽  
Vol 733 ◽  
Author(s):  
Brock McCabe ◽  
Steven Nutt ◽  
Brent Viers ◽  
Tim Haddad
Keyword(s):  
High Temperature ◽  
Sample Preparation ◽  
Room Temperature ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Polyurethane Foams ◽  
Development Projects ◽  
Polymer Systems ◽  
Polyurethane Resin ◽  
Military Development

AbstractPolyhedral Oligomeric Silsequioxane molecules have been incorporated into a commercial polyurethane formulation to produce nanocomposite polyurethane foam. This tiny POSS silica molecule has been used successfully to enhance the performance of polymer systems using co-polymerization and blend strategies. In our investigation, we chose a high-temperature MDI Polyurethane resin foam currently used in military development projects. For the nanofiller, or “blend”, Cp7T7(OH)3 POSS was chosen. Structural characterization was accomplished by TEM and SEM to determine POSS dispersion and cell morphology, respectively. Thermal behavior was investigated by TGA. Two methods of TEM sample preparation were employed, Focused Ion Beam and Ultramicrotomy (room temperature).

FANSTEEL 85 METAL

Alloy Digest ◽  
1981 ◽  
Vol 30 (6) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Creep Strength ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Base Alloy ◽  
Heat Treating ◽  
Good Combination ◽  
Bend Strength ◽  
Temperature Performance

Abstract FANSTEEL 85 METAL is a columbium-base alloy characterized by good fabricability at room temperature, good weldability and a good combination of creep strength and oxidation resistance at elevated temperatures. Its applications include missile and rocket components and many other high-temperature parts. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, tensile properties, and bend strength as well as creep. It also includes information on low and high temperature performance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Cb-7. Producer or source: Fansteel Metallurgical Corporation. Originally published December 1963, revised June 1981.

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