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Corundum

Corundum is a crystalline form of aluminum oxide (Al2O3) that occurs naturally in a variety of colors, including the precious gemstones ruby and sapphire.
This hard, wear-resistant mineral is commonly used in abrasives, cutting tools, and other industrial applications.
Corundum's unique physical and chemical properties make it an important material in many fields, from jewelry and electronics to aerospace enginering.
Though rarely found in large deposits, corundum's versatility and durability have made it a valuable resource throughout history.1

Most cited protocols related to «Corundum»

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Publication 2011
Acetone Acids ammonium fluoride Corundum Gamma Rays Hydrofluoric acid Neoplasm Metastasis Nitric acid Operative Surgical Procedures Radiotherapy Sulfuric Acids

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Publication 2011
Acetone Acids ammonium fluoride Corundum Gamma Rays Nitric acid Nitrogen Normal Saline Radiotherapy Titanium
TiO2, CeO2, and standard aluminum dioxide (Al2O3) were obtained from Sigma Aldrich (Burlington, MA, USA). No further purification was performed of the powder samples. The PXRD data were collected using a Rigaku diffractometer (Tokyo, Japan), operating with CuKα radiation (1.5406 Å) at 50 kV and 100 mA. The diffractograms were collected using a step scanning configuration between = 20°–100° for CeO2 and TiO2, with 0.02° and 5s per step. The crystallographic phases were identified using Match-Phase Identification from Powder Diffraction software (version3, Crystal Impact, Germany) using the crystallographic cards (96-434-3162) and (96-500-022) with the crystallographic information files (CIF) #9009008 and #5000223 for the CeO2 and TiO2 anatase phases, respectively. The OriginPro 9.0 software was used to estimate the FWHM, using a pseudo-Voigt fitting model corrected by the instrumental resolution function (IRF) obtained from the standard corundum (see Figure S1).
For the RM of the diffractograms, the software FullProf Suite (version July 2001) was employed, the CeO2 and TiO2 crystallographic information files (CIF) obtained from Match v3 software were used as initial parameters, which crystallographic data for CeO2 were cubic crystalline structure, space group Fm-3m, and cell parameter a = 5.4110 Å. For TiO2 anatase, they were tetragonal crystalline structure, space group I 41/amd, cell parameters a = 3.78435 Å and c = 9.50374 Å. For both cases the Caglioti initial parameters were U = 0.004133, V = −0.007618, and W = 0.006255. Refinement was done using the Thompson–Cox–Hastings (TCH) pseudo-Voigt Axial divergence asymmetry function. Finally, the average crystallite size was determined in the FullProf Suite program. To do that, we first characterized the Al2O3 standard. The used experimental conditions were = 10°–80° with a step of 0.02°. For the Al2O3 refinement, the TCH profile was employed to obtain the instrumental parameters of the equipment, which was added to the instrumental resolution file (IRF) and later used to determine the average crystallite sizes of the CeO2 and TiO2 NPs.
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Publication 2021
Aluminum anatase Cells Corundum Crystallography Cuboid Bone Powder Radiation
The starting material was a diatomite, i.e. a tripolaceous siliceous rock (Tripoli rock) cropping out in the Crotone Basin in southern Italy. Tripoli was analysed by X-ray diffraction (XRPD) with a Siemens D5000 operating with a Bragg-Brentano geometry; CuKα = 1.518 Å, 40 kV, 40 mA, 2–35° scanning interval, step size 0.020° 2θ with a scan rate of 13 sec/step. Characterization of this material revealed a mineralogical assemblage mainly consisting of an amorphous siliceous fraction (diatoms and sponges, visible as the bulge in the range 17–25°2theta) with minor presences of quartz, montmorillonite, chlorite, kaolinite, K-micas and small amounts of calcite (Fig. 1). Chemical analysis of Tripoli rock is reported in Table 1 and was performed by X-ray fluorescence analysis (Axios-Max Advanced Panalytical; 60KV; 160 mA; 4000 W; 0.0001°2 θ). We considered the value of LOI of 1 g of sample obtained in ceramic meltpots running in an oxidizing furnace.

XRPD pattern of “Tripoli rock”.

Chemical composition of “Tripoli rock” analysed by X-ray fluorescence.

Tripoli rock
SiO281.07 (0.45)
TiO20.26 (0.02)
Al2O35.03 (0.02)
Fe2O32.14 (0.03)
MnO0.07 (0.01)
MgO1.11 (0.01)
CaO1.72 (0.03)
Na2O0.25 (0.02)
K2O0.68 (0.02)
P2O50.07 (0.01)
LOI7.73 (0.03)
Tot.100.13 (0.18)

The standard deviation values calculated for three analyses are reported in brackets. LOI: loss on ignition.

The synthesis of leucite was conducted through the mixing of silicate and aluminate solutions. These solutions were prepared according to the procedure already described in Novembre et al.24 (link) In the present study, 5.19 g of the ground and powdered Tripoli material were treated with HNO3 (65%), in order to dissolve the calcite fraction in order to remove the soluble calcite fraction from the starting material. The diatomitic sample (ca. 5 g after the HNO3 treatment) was added to 50 mL of KOH (6.8%). This solution was thoroughly mixed with a magnetic stirrer for 2 h and then put in a teflon reactor/bomb and heated in an oven at 80 °C for 24 h. After filtration, the remnant solid and insoluble fraction, which consisted of clay minerals and quartz, was separated from the silicate solution. The resulting molar composition of the solution was 0.060 K2O–0.026SiO2–0.625H2O with traces as follows: 2.01 ppm Mg, 2.11 ppm Ca and Al, Ti and Mn lower than 0.1 ppm. Based on a mass balance calculation following this step-wise chemical separation process, the Tripoli rock was determined to be composed of: 63.27 wt% amorphous silica (diatoms and sponges), 32 wt% of clay minerals and quartz, and 3.83 wt% calcite.
The aluminate solution was prepared as follows: 0.45 g of Al(OH)3 (65%) was mixed with 50 mL of KOH (6.8%). The obtained aluminous solution with a composition of 0.060 K2O–0.0076Al2O3–0.625 H2O (Mn, Ti and Mg < 0.01 ppm; Fe < 0.4 ppm; K, Ca and Si < 0.2 ppm) was then heated at 100 °C for one hour.
A series of three syntheses were carried out by varying the volume ratio of the two solutions according to Table 2.

Starting mixture and relative obtained mineralogical assemblages of experimental runs.

synthesis runstarting mixtureSiO2/Al2O3mineralogical assemblage
110 ml siliceous sol + 10 ml aluminous sol3.40KAlSi2O6 + KAlSIO4-O1 (1.5–20 h); KAlSi2O6 (24 h)
212.5 ml siliceous sol + 7.5 ml aluminous sol5.70KAlSi2O6 + KAlSIO4-O1 (1.5–15 h); KAlSi2O6 (20 h)
310 ml siliceous sol + 5 ml aluminous sol6.80KAlSi2O6 + KAlSIO4-O1 (3 h); KAlSi2O6 (15–20 h)
The reactants were vigorously mixed for two hours with a magnetic stirrer. Each mixture was heated inside an autoclave at 150 °C and ambient pressure for a duration of one hour. The hydrothermally derived gel precursors were recovered from the reactors, filtered from the solution, thoroughly washed with distilled water and dried in an oven at 40 °C for 24 hours. These gel products were examined by XRPD analysis (Fig. 2) in order to assess their amorphous character. The three gel precursors were then calcined at 1000 °C with periodic sampling carried out at scheduled intervals.

XRPD patterns of the hydrothermal gel precursors. (a): synthesis run 1; (b): synthesis run 2; (c) synthesis run 3.

All intermediate and final products of the three syntheses were analysed by XRPD under the same operating conditions as those for the “Tripoli rock” analysis. Identification of phases and relative peak assignment were made with reference to the following JCPDS codes: 00-038-1423 for leucite and 00-011-0579 for KAlSIO4-O1. The amounts of both the crystalline and amorphous phases in the synthesis powders were estimated using Quantitative Phase Analysis (QPA) applying the combined Rietveld and Reference Intensity Ratio (RIR) methods; corundum NIST 676a was added to each sample, amounting to 10%, and the powder mixtures were homogenized by hand-grinding in an agate mortar. Data for the QPA refinement were collected in the angular range 5–70° 2θ with steps of 0.02° 2θ and 10 s step−1, a divergence slit of 0.5° and a receiving slit of 0.1 mm.
Data were processed with the GSAS software28 and the graphical interface EXPGUI29 (link). The unit cell parameters were determined, starting with the structural models proposed by Dove et al.30 for leucite and Kremenovic et al.31 (link) for KAlSiO4-O1. Parameters were refined following Novembre et al.25 (link).
Analysis of synthesized powders was performed by inductively coupled plasma optical emission spectroscopy (ICP-OES, Perkin Elmer Optima 3200 RL) after alkaline fusion of the sample in a Pt crucible (lithium meta-tetra borate pearls, at 3/2 ratio) and subsequent acid solubilization27 (link).
Scanning electron microscope (SEM) analyses were carried out with a JEOL JSM-840 with operating conditions of 15 kV and window conditions ranging from 18 to 22 mm, following the procedure as explained in Ruggieri et al.32 (link).
Vibrational spectra of the synthesized products were obtained with an Infrared spectrometer FTLA2000, equipped with SiC (Globar) filament source, KBr beamsplitter and DTGS detector. Samples were prepared according to the method of Robert et al.33 (link) using powder pressed pellets (sample/KBr ratio of 1:100); spectra were processed with the program GRAMS-Al.
Thermal behaviour of gel precursors were studied by differential thermal analysis and thermogravimetry (DTA-TG) by means of a Mettler TGA/SDTA851e instrument (10°/minute from 30° to 1100 °C, using an approximate sample weight of 10 mg in Al2O3 crucible).
Density of leucite was measured by He-picnometry using an AccuPyc 1330 pycnometer.
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Publication 2019
Acids Anabolism Calcite Cells Character Chemical Processes chlorite Clay Columbidae Corundum Cytoskeletal Filaments diatomite Diatoms Differential Thermal Analysis dolutegravir Filtration Fluorescence Kaolinite leucite lithium borate mica Minerals Molar Montmorrillonite Pellets, Drug Plasma Porifera Powder Pressure Quartz Radionuclide Imaging Roentgen Rays Scanning Electron Microscopy Silicates Silicon Dioxide SLIT1 protein, human Spectrum Analysis Teflon Tetragonopterus Thermogravimetry Vibration Vision X-Ray Diffraction
In order to evaluate contraction stress, which generates during photopolymerization of resin composites, transparent and photosensitive plates made of epoxy resin (Epidian 53, Organika-Sarzyna SA, Nowa Sarzyna, Poland) were used. The calibrated orifices (3 mm in diameter and 4 mm in thickness) in resin plates were prepared. The circular shape and size of orifices was meant to mimic an average tooth cavity. To obtain higher micromechanical retention, surface of the plates was sandblasted with a 50-μm grain corundum Cobra (Renfert, Hilzingen, Germany). Thus, prepared plates were immersed in distilled water for 3 months to eliminate errors associated with water sorption of resin. Next, dedicated bonding system was applied and cured with Elipar S10 lamp (3M ESPE, Landsberg am Lech, Germany) (Table 3). The orifices were filled with tested material in one layer. Three samples were prepared for each material. The polymerization was performed according to the manufacturer’s instructions (Table 2 and Table 3). Both light curing units (Mini L.E.D and Elipar S10) had an output irradiance of 1250 mW/cm2 and 1450 mW/cm2, respectively, as stated by the manufacturer. To ensure consistent irradiance values, the light curing units were calibrated with radiometer system (Digital Light Meter 200 from Rolence Enterprice Inc., Taoyuan, Taiwan).
Next, samples were stored in distilled water at room temperature. After selected period of time (30 min, 24 h, 72 h, 120 h, 168 h, 240 h, 336 h, 504 h, 672 h, and 1344 h), the generated strains in the plates were visualized in circular transmission polariscope FL200 (Gunt, Hamburg, Germany). Photoelastic images were registered by digital camera (Canon EOS 5D Mark II/Canon Inc., Tokyo, Japan), both in parallel and perpendicular orientation of filter polarization planes. Met-Ilo computer program (J. Szala, 2012, Poland) was applied to determine the arrangement and the dimension of interference fringes. The analysis of stress and strain was carried out in a two-dimensional state of the stress and three-dimensional state of deformations. The analysis of stress and strain was carried out in a two-dimensional state of the stresses and three-dimensional state of deformations. Additionally, the calculation was conducted following this assumption: the relative change in composite volume caused the extension of composite and the extension of base material being “tooth model” (epoxy resin plate). Accordingly, it was possible to determine the radial and circumferential stresses based on the Equations (4) and (5) given by Timoshenko [43 ]: σr=a2·psb2a2·(b2r21)
σθ=a2·psb2a2·(b2r2+1)
where σr—the radial stress, σθ—the circumferential stress, ps—the shrinkage stress around composite filling, a—the radius of the internal orifices in the plate, b—the radius of the largest of isochromatic fringe, and r—the radius contained in the region from a to b.
Upon calculating the shrinkage stress on the circumference of the orifices, the radial and circumferential stresses were determined on the basis of Equations (2) and (3).
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Publication 2017
Cereals Cobra Composite Resins Corundum Dental Pulp Cavity epidian Epoxy Resins Fingers Light Models, Dental Photosensitization Polymerization Radius Resins, Plant Retention (Psychology) Strains Transmission, Communicable Disease Vita Mark II

Most recents protocols related to «Corundum»

First, an ethanol solution of IrCl3 (3 mg mL–1, 100 mL) and KOH aqueous solution (KOH, 9 M, 300 mL) were stirred continuously at 150 °C in a Teflon mortar to form a uniform dark blue slurry. Then, the slurry was transformed into a homemade mechano-thermal corundum reactor that was fixed in a muffle furnace. The reactor was heated to different temperatures (300–700 °C) by stirring for 2 h. After cooling to room temperature, the samples were washed with double-distilled water and dried by lyophilization. When the heating temperature was 700 °C, the IrO2NR samples were obtained. The fabrication process is schematically shown in Supplementary Fig. 1.
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Publication 2023
Corundum Ethanol Freeze Drying Teflon
Commercial Cr2O3 (3 μm, 99.5%, Sinopharm Chemical Reagent Co., Ltd.), GeO2 (500 nm, 99.9%, Sinopharm Chemical Reagent Co., Ltd.), graphite powders (10 nm, 99.8%, Sinopharm Chemical Reagent Co., Ltd.) with different molar ratios (1:1:1, 1:2:1, 1:3:1, and 1:4:1), and 10 wt% polyvinyl butyral (PVB, Sinopharm Chemical Reagent Co., Ltd.) were mixed by ball-milling at 300 r/min for 5 h to prepare the powdered Cr2O3/GeO2/C precursor. About 0.5 g of the obtained mixed powders were pressed under 10 MPa to fabricate a Cr2O3/GeO2/C disc (10 mm in diameter). The Cr2O3/GeO2/C disc was wrapped by nickel foam and fixed on a Mo wire (2 mm in diameter, Shanghai Non-Ferrous Metals (Group) Co., Ltd.) to form the Cr2O3/GeO2/C cathode system. A high-purity graphite rod (5 mm in diameter, 99.999%, Shanghai Carbon Co., Ltd.) fixed with the Mo wire was used as the anode. CaCl2 and NaCl (Shanghai Aladdin Biochemical Technology Co., Ltd.) were commonly baked at 300–400°C for 24–48 h and then used as electrolytes in a 1:1 M ratio. The electrodes and mixed salts were assembled in a corundum crucible to form an electrolytic cell, which was then placed in an electrolysis furnace sealed on one end. High-purity Ar gas was continuously introduced into the electrolytic furnace to create an inert atmosphere. The electrolysis furnace temperature was then ramped up to 700°C with a heating rate of 5°C/min. Pre-electrolysis was then performed between two graphite rods (5 mm in diameter, 99.999%, Shanghai Carbon Co., Ltd.) at 2.0 V for 2–5 h to eliminate residual purities in molten salts. A constant voltage of 3.0 V was applied between the Cr2O3/GeO2/C cathode and the graphite anode for pre-set times. After electrolysis, the obtained electrolytic samples were washed with deionized water to remove solid salts and then, dried at 100°C in a vacuum drying oven for further characterization.
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Publication 2023
Atmosphere Carbon Cells Corundum Electrolysis Electrolytes germanium dioxide Graphite Metals Molar Nickel polyvinylbutyral Powder Rod Photoreceptors Salts Sodium Chloride Vacuum
A model tire tread compound was prepared using NR (TSR20, 100 phr), carbon black (N234, 60 phr), processing oil (5 phr), stearic acid (3 phr), zinc oxide (4 phr), anti-degradants (total 4 phr), N-tert-butylbenzothiazole-2-sulfenamide (TBBS, 1.1 phr), N-(cyclohexylthio)phthalimide (CTP, 0.3 phr), and sulfur (1.6 phr). Mixing was performed in a Banbury-type mixer, and the initial temperatures of the mixer were 110 and 80 °C for the masterbatch (MB) and final mixing (FM) stages, respectively. The abrasion specimens were prepared by curing the rubber compound at 160 °C for the maximum cure time (tmax) in a compression mold (83 mm diameter and 19 mm thickness). Acetone, tetrahydrofuran (THF), n-hexane, and toluene were purchased from Aldrich Co. (Wyoming, IL, USA).
Three samples were prepared (Table 1): (1) untreated sample (sample code: NR0), (2) thermally aged sample (sample code: NRth), and (3) thermally aged sample after pre-abrasion (sample code: NRabth). Thermal aging was performed at 80 °C for 30 days in a convection oven. The aging temperature of 80 °C was determined by considering efficient thermal aging did not cause abnormal effects at high temperatures [41 (link),42 ,43 ]. The aging effect at 80 °C might correspond to about 16 times compared to that at 40 °C [44 (link),45 (link)].
An abrasion test was performed using a LAT100 tire tread compound tester of the VMI group (Gelderland, The Netherlands). Electro Corundum Disc Grain, 60 of VMI group (Gelderland, The Netherlands), was used as the abrasive disk. The load force was 75 N, and the velocity was 25 km/h. After the abrasion test, the wear particles were collected and separated by size using a sieve shaker of Octagon 200 (Endecotts Co., London, UK). Standard test sieves of 1000, 500, 212, 106, and 63 μm were used. The wear particles were divided into five groups; 63–106, 106–212, 212–500, 500–1000, and larger than 1000 μm.
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Publication 2023
Acetone Carbon Black Cereals Convection Corundum Fever Fungus, Filamentous maximum cure n-hexane phthalimide Rubber stearic acid sulfenamide Sulfur TERT protein, human tetrahydrofuran Toluene Zinc Oxide
The thermogravimetric instrument (STA449F3, Selbu, Bavaria, Germany) was employed to measure the composition and relative content of hydration products of different binders. The hydrated sample powder weighed about 20 mg and was placed in a corundum crucible. The sample together with the Al2O3 crucible was elevated from room temperature of 25 °C to 800 °C at N2 with a controlled heating rate of 10 °C/min. The content of chemically bound water (BW) and portlandite (CH) was calculated according to Equation (4) and Equation (5) [56 (link)], respectively.
WBW=W50W550W550×100
WCH=(W400W500)W550×7418×100 
where the W50, W400, W500, and W550 was the weight of specimens at 50 °C, 400 °C, 500 °C, and 550 °C.
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Publication 2023
Corundum Fever Powder
Using XRD analysis and the Rietveld refinement technique, the phase composition of cement paste was quantitatively investigated. XRD patterns were employed a D8 Advance diffractometer at 40 kV and 100 mA with CuKa radiation. The scanning range of 5~70° with a step length of 0.01°. Corundum (α-Al2O3, 10%) was used as an internal standard, and mixed with the stop cement powder. The Rietveld calculation was carried out by using TOPAS Academic V5.
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Publication 2023
Corundum Dental Cements Paste Powder Radiotherapy

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More about "Corundum"

Corundum, a crystalline form of aluminum oxide (Al2O3), is a versatile and valuable mineral with a wide range of applications.
This hard, wear-resistant material is commonly found in a variety of colors, including the precious gemstones ruby and sapphire.
Corundum's unique physical and chemical properties make it an important material in many fields, from jewelry and electronics to aerospace engineering.
Corundum is often used in abrasives, cutting tools, and other industrial applications due to its exceptional hardness and durability.
The D8 Advance, Pulverisette 7, and D2 Phaser are examples of instruments used to analyze and characterize corundum samples.
The JXA-8230 electron microprobe and the V-660 spectrometer are also employed to study the chemical composition and optical properties of corundum.
In the field of thermal analysis, the TG 209 F3 Tarsus and the STA 449 F1 Jupiter instruments are commonly used to investigate the thermal behavior of corundum, such as its phase transitions and decomposition.
The TG 209 F1 Libra is another instrument that can be used for similar analyses.
Corundum's versatility extends to the field of X-ray diffraction, where the PILATUS 100K detector is used to study the crystal structure and phase composition of corundum samples.
The Model 6614C is an example of a versatile power supply that can be used to power various instruments used in corundum research.
Despite its rarity in large deposits, corundum's unique properties and widespread applications have made it a valuable resource throughout history.
Whether in the form of ruby, sapphire, or other varieties, corundum continues to be an important material in a wide range of industries and applications.