Rheological Behavior of Silicon Nitride Whiskers

1992 ◽  
Vol 287 ◽  
Author(s):  
Patricio Toro ◽  
Oscar Wittke
Keyword(s):  
Rheological Behavior ◽  
Carbothermal Reduction ◽  
Ceramic Body ◽  
Flow Behavior ◽  
Aqueous Suspension ◽  
Slip Casting ◽  
Sem Analysis ◽  
Ftir Analysis ◽  
Rice Husks ◽  
X Ray

ABSTRACTSi3N4 whiskers are found through SEM analysis of powder obtained by carbothermal reduction of calcined Chilean rice husks. X-ray and FTIR analysis showed that the ceramic material was mainly α-Si3N4. A stable aqueous suspension with 30 or 40 wt% Si3N4 was obtained at pH = 8.5. A maximum viscosity at pH = 4.0 and low rpm was also observed and this rheological behavior is consistent with the zeta potential data. An irregular flow behavior near pH 4.0 shows a decrease in viscosity that is related to active impurities as detected by potentiometric titrations.These rheological studies conducted allowed production of a Si3N4 green ceramic body measuring 170 × 25 × 5 mm formed by slip casting. The optimal aqueous suspension of powder contained the following: 17.0 g Si3N4, 1.0 g Cu2O, 1.3 g bentonite, and 20.0 g water.

Facile Electrospinning Preparation of Y3Al5O12 Nanobelts

2013 ◽  
Vol 448-453 ◽  
pp. 3041-3045
Author(s):  
Fei Bi ◽  
Xiang Ting Dong ◽  
Jin Xian Wang ◽  
Gui Xia Liu ◽  
Wen Sheng Yu
Keyword(s):  
Sol Gel ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Ftir Analysis ◽  
X Ray ◽  
Novel Structure ◽  
Group I ◽  
Sol Gel Process ◽  
Composite Nanobelts ◽  
Scanning Electron

PVP/[Y(NO3)3+Al (NO3)3] composite nanobelts were fabricated via electrospinning combined with sol-gel process and novel structure of Y3Al5O12(denoted as YAG for short) nanobelts have been obtained after calcination of the relevant composite nanobelts. The structural properties were characterized by X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). XRD analysis indicated that the composite nanobelts were amorphous, and YAG nanobelts were cubic in structure with space group Ia3d. FTIR analysis manifested that pure YAG nanobelts were formed at 900oC. SEM analysis and histograms revealed that the width of the composite nanobelts and YAG nanobelts were 3.5 μm and 2.4 μm, and the thickness were 240 nm and 112 nm, respectively, under the 95% confidence level. The formation mechanism of YAG nanobelts was discussed in detail.

Effect of Dispersant Addition on Properties of Ceramic Pieces from Kampung Dengir, Besut, Terengganu, Malaysia

2017 ◽  
Vol 888 ◽  
pp. 28-32
Author(s):  
Noor Asliza Ismail Adnen ◽  
Nur Atiqah Azwa Joulme Morad ◽  
Mohd Aidil Adhha Abdullah ◽  
Mohd Al Amin Muhamad Nor
Keyword(s):  
Water Absorption ◽  
Rheological Behavior ◽  
Ceramic Body ◽  
X Ray ◽  
Test Pieces ◽  
Ceramic Slurry ◽  
Sample Characterization ◽  
Ball Clay ◽  
Good Flow

The abundancy of ball clay can be transform into more useful form. This study was conducted to investigate the effect of different amount of dispersant on ceramic system. Ball clay from Kampung Dengir, Besut, Terengganu was used as starting powder while sodium silicate was used as dispersant to produce good flow ability, minimum viscosity and controllable ceramic slurry. Ceramic slurry was prepared by adding additives such as binder, flux, filler and dispersant, casted onto POP mould to obtain ceramic body. Ceramic then cut into test pieces (8cm x 2cm) and mixed for 2 h and aged for 2 days before dried at 70 °C overnight and sintered at temperature of 800-1200 °C in furnace for 2 h with heating rate 5 °C/min. Slurries also tested for rheological properties using rheometer (brand Thermo Haake). Viscosity and shear stress were measured to investigate the rhoelogical behaviour of slip with different amount of dispersant (0.03 mL to 0.06 mL/200 mL of sample). Characterization of raw samples has been done using X-ray diffractometer (XRD) showing the presence of kaolinite and quartz. Effect of dispersant on rheological behavior, rate of shrinkage, water absorption, porosity and density were investigated It was found that increase in amount of dispersant added exhibit the best rheological behavior, and 0.05 mL dispersant was the optimum amount in term of rate of shrinkage, water absorption, porosity and density. As a conclusion, 0.05 mL was the optimum dispersant which gives best rheological behavior and almost fault-free ceramic bodies

scholarly journals Dimensional Stability of Treated Sengon Wood by Nano-Silica of Betung Bamboo Leaves

Forests ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1581
Author(s):  
Istie Rahayu ◽  
Fitria Cita Dirna ◽  
Akhiruddin Maddu ◽  
Wayan Darmawan ◽  
Dodi Nandika ◽  
...  
Keyword(s):  
Dimensional Stability ◽  
Wood Quality ◽  
Wood Properties ◽  
Sem Analysis ◽  
Impregnation Method ◽  
Ftir Analysis ◽  
Nano Silica ◽  
X Ray ◽  
Wood Modification ◽  
Bamboo Leaves

Sengon (Falcataria moluccana Miq.) is one of the fastest growing wood that is broadly planted in Indonesia. Sengon wood has inferior wood properties, such as a low density and dimensional stability. Therefore, sengon wood requires a method to improve its wood quality through wood modification. One type of wood modification is wood impregnation. On the other hand, Betung Bamboo leaves are considered as waste. Betung Bamboo leaves contain silica. Based on several researches, nano-SiO2 could improve fast-growing wood qualities. According to its perfect solubility in water, monoethylene glycol (MEG) is used in the study. The objectives are to evaluate the impregnation treatment (MEG and nano-silica originated from betung bamboo leaves) in regard to the dimensional stability and density of 5-year-old sengon wood and to characterize the treated sengon wood. MEG, MNano-Silica 0.5%, MNano-Silica 0.75%, and MNano-Silica 1% were used as impregnation solutions. The impregnation method was started with 0.5 bar of vacuum for 60 min, followed by 2.5 bar of pressure for 120 min. The dimensional stability, density, and characterization of the samples were studied through the use of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results show that the treatment had a significant effect on the dimensional stability and density of sengon wood. Alterations in the morphology of treated sengon wood were observed through the full coverage of the pits on the vessel walls (SEM analysis results) and the detection of ethylene (FTIR analysis results) and silica (XRD and FTIR analysis results). Overall, the 0.75% MNano-Silica treatment was the most optimal treatment for increasing the dimensional stability and density of 5-year-old sengon wood.

Rheology and Rotational Rheometry of Concentrated Clay Based Ceramic Suspensions: Steps From Measured to Relevant Data

2010 ◽  
Author(s):  
Jana Andertova´ ◽  
Frantisˇek Rieger
Keyword(s):  
Experimental Data ◽  
Rheological Behavior ◽  
Flow Behavior ◽  
Slip Casting ◽  
Rheological Parameters ◽  
Technological Parameters ◽  
Flow Curves ◽  
Rotational Viscometer ◽  
Flow Behavior Index ◽  
Ceramic Suspensions

The rheological behavior of ceramic suspensions affects significantly wet ceramic processing. On the base of knowledge of rheological parameters the technological parameters of various processes (mixing, batching, spray drying, slip casting, of rheological parameters the selection of proper geometry and sensors must be done. From the data measured the flow curves must be designed and parameters of appropriate rheological models must be calculated. The power-law is the simplest model mostly used for description of rheological behavior of non-Newtonian fluids. Using this model, the dependence of shear stress on shear rate can be expressed. The aim of this paper is to show how the flow curves necessary for parameters of rheological model evaluation can be obtained from primary experimental data received from measurements on rotational viscometer. The two arrangements of rotational viscometer method were used in rheological measurements. The procedure of experimental data to obtain parameters K (coefficient of consistency) and n (flow behavior index) is presented.

Tailored Rheological Behavior of Mullite and BSAS Suspensions Using a Cationic Polyelectrolyte

2005 ◽  
Author(s):  
Glen H. Kirby ◽  
Kevin M. Cooley ◽  
Beth L. Armstrong
Keyword(s):  
Yield Stress ◽  
Rheological Behavior ◽  
Elastic Moduli ◽  
Flow Behavior ◽  
Critical Concentration ◽  
Aqueous Suspension ◽  
Aqueous Media ◽  
Shear Thinning ◽  
Dip Coating ◽  
Cationic Polyelectrolyte

The effects of a cationic polyelectrolyte, polyethylenimine, on the rheological behavior of aqueous mullite and celsian phase, barium strontium aluminosilicate (BSAS) suspensions have been studied to optimize a dip-coating process. The surface of the ceramic particles was characterized in aqueous media using zeta potential measurements. The ionization behavior and hydrodynamic radius of polyethylenimine in aqueous media was characterized by potentiometric titration and dynamic light scattering measurements, respectively. The rheological behavior of concentrated ceramic suspensions containing polyethylenimine was characterized by stress viscometry and elastic modulus measurements. Polyethylenimine imparts repulsive, electrosteric interactions between mullite and BSAS particles in aqueous suspension, resulting in shear thinning flow behavior, linear elastic moduli, and yield stress values that are minimized for suspensions with a critical PEI concentration of 0.2 mg PEI per m2 of mullite and 0.4 mg PEI per m2 of BSAS, respectively. The elastic moduli and yield stress of mullite and BSAS suspensions were nearly identical at equivalent fractions of their critical PEI concentration. Uniform coatings were obtained upon dipping SiC, Si3N4, and Si-metal substrates into shear-thinning suspensions containing PEI at 81–88% of the critical concentration. Dense mullite coatings were demonstrated on SiC substrates after sintering at 1400°C.

scholarly journals Investigation of Intercalation of Sodium-Montmorillonite with Octadecyl Trimethyl Ammonium Bromide Surfactant

2017 ◽  
Vol 5 (1) ◽  
Author(s):  
Chanra J.B Soegijono
Keyword(s):  
Aqueous Suspension ◽  
Interlayer Spacing ◽  
Xrd Analysis ◽  
Dispersion Analysis ◽  
Sem Analysis ◽  
Ammonium Bromide ◽  
X Ray Diffraction ◽  
Sodium Montmorillonite ◽  
X Ray ◽  
Scanning Electron

Sodium-montmorillonite (Na+-MMT) was intercalation modified with octadecyl trimethyl ammonium bromide (OTAB) in aqueous suspension via an ion exchange mechanism. Fourier transform infrared spectroscopy (FTIR) study indicates that OTAB is successfully intercalated into Na+-MMT layers and/or adsorbed on the surface of Na+-MMT. X-ray diffraction (XRD) analysis revealed that the interlayer spacing of the Na+-MMT was extended with the content of OTAB increasing, and the maximum spacing can reach about 3.80 nm. Results of scanning electron microscopy (SEM) analysis reveals the morphologies change from spherical-like particles to high-aspect ratio flakes after modification. Different configurations of OTA+ chains within MMT interlayer are proposed based on the above analysis. The results of contact angle and the dispersion analysis show that the surface wettability of Na+-MMT is converted from hydrophilic to organophilic.

Fabrication of Tapered Bio Mimetic Cilia Using Bulk Lithography and Ceramic Mold

2014 ◽  
Author(s):  
Chandrashekar V. Adake ◽  
Parag Bhargava ◽  
Prasanna S. Gandhi ◽  
Bhargava Kashyap
Keyword(s):  
Soft Lithography ◽  
Ceramic Body ◽  
Aqueous Suspension ◽  
Slip Casting ◽  
Single Layer ◽  
Ceramic Mold ◽  
Green Body ◽  
Polydimethyl Siloxane ◽  
Casting Technique ◽  
Negative Impression

This paper presents fabrication of tapered, high aspect ratio bio mimetic cilia from Nickel-polydimethyl siloxane (Ni-PDMS) composite by using bulk lithography technique and ceramic molding. Many research groups suggested fabrication of bio mimetic cilia using various techniques which are based on soft lithography and VLSI techniques. Recently a novel single layer micro fabrication technique known as ‘bulk lithography’ which uses an unconstrained photopolymer has been reported by co-authors. This technique is used to fabricate a polymer cilia pattern (an array of photopolymerised inverted cone profile) and using this pattern a ceramic green body is fabricated by slip casting technique. An aqueous suspension containing sub micron size alumina is used to cast ceramic green body. After casting this cilia pattern makes negative impression of tapered holes on green ceramic body. During sintering of green ceramic body the polymer burns off resulting in ceramic mould with tapered holes imprinted on it. This mold retains shape of a tapered hole though it shrinks in size after sintering. This mold is used further to cast Ni-PDMS composite in the form of cilia structures.

REMOVAL ENHANCEMENT OF BASIC BLUE 41 BY RGO–TiO2 NANOCOMPOSITE SYNTHESIZED USING PULSED LASER

2018 ◽  
Vol 25 (01) ◽  
pp. 1850041 ◽  
Author(s):  
FATEMEH GHASEMI ◽  
SALIMEH KIMIAGAR ◽  
MOZHGAN SHAHBAZI ◽  
HOSSEIN VOJOUDI
Keyword(s):  
Pulsed Laser ◽  
Sem Analysis ◽  
Langmuir Model ◽  
Ftir Analysis ◽  
X Ray Diffraction ◽  
Pulse Laser Irradiation ◽  
Nanocomposite Structure ◽  
X Ray ◽  
Optimum Ph ◽  
Scanning Electron

Graphene oxide (GO) and GO-TiO2 nanocomposite was produced then reduced under pulse laser irradiation (RGO–TiO[Formula: see text]. Basic blue 41 (bb41) dye was removed from aqueous solutions by using RGO–TiO2 nanocomposites. The UV–Vis absorption and FTIR analysis were utilized to confirm the reduction of GO-TiO2 to RGO–TiO2. The results showed complete reduction of GO. X-ray diffraction (XRD), Raman spectra and scanning electron microscopy (SEM) analysis were applied to approve the RGO–TiO2 nanocomposite structure. The effect of pH on the bb41 removal by RGO–TiO2 was studied varying the pH from 1 to 11. The optimum pH and adsorbent dosage were found to be 9 and 0.2[Formula: see text]g/L with 98% efficiency, respectively. The calculated coefficients demonstrated that the Langmuir model was fixed to the experimental data. The results indicated that RGO–TiO2 could be engaged as an exceptional sorbent to remove bb41 dye which is in aqueous solution.

Investigation of the products of carbothermal reduction of yttrium oxide by the hydrolysis method

1984 ◽  
Vol 49 (4) ◽  
pp. 936-943 ◽  
Author(s):  
Bohumil Hájek ◽  
Pavel Karen ◽  
Vlastimil Brožek
Keyword(s):  
Yttrium Oxide ◽  
Carbothermal Reduction ◽  
Stoichiometric Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrolysis Method ◽  
Sample Decomposition ◽  
Products Of Reaction ◽  
Hydrolysis Of ◽  
Lower Carbon

For the investigation of the products of reaction of yttrium oxide with carbon mixed in various proportions, the chemical and X-ray diffraction methods of analysis were combined with the gas chromatographic analysis of the mixture of hydrocarbons and hydrogen formed on the sample decomposition with water. The carboreduction of Y2O3 was examined at relatively low temperatures, convenient for obtaining the reaction intermediates in higher yields. At 1 600 °C and pressures of 10-3 Pa the reduction of a mixture of Y2O3 with carbon in a stoichiometric ratio of 1 : 7 yields YC2 in equilibrium with 20% of Y2OC phase. At lower carbon contents (down to the Y2O3 : C ratio of 1 : 2) tha fraction of the Y2OC phase increases up to approximately 30%. In addition to Y2O3, the reaction mixture contains also Y2C, Y2OC and a phase giving propyne on hydrolysis. The presence of traces of C3 hydrocarbons and small amounts of methane in the product of hydrolysis of the carbide sample prepared by the carbothermal reduction of the oxide can be explained in terms of the occurrence of the Y15C19 phase, probably substituted in part by oxygen, and of the Y2OC phase. The results are compared with those obtained previously for the Sc2O3 + C system.

scholarly journals Incorporation of silver stearate nanoparticles in methacrylate polymeric monoliths for hemeprotein isolation

2020 ◽  
Vol 18 (1) ◽  
pp. 399-411
Author(s):  
Eman Alzahrani
Keyword(s):  
Noble Metals ◽  
Extraction Process ◽  
Sem Analysis ◽  
X Ray ◽  
Polymeric Scaffold ◽  
Extended Surface ◽  
Unique Method ◽  
Unique Approach ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

AbstractA unique method was used to synthesize extremely stable silver stearate nanoparticles (AgStNPs) incorporated in an organic-based monolith. The facile strategy was then used to selectively isolate hemeproteins, myoglobin (Myo) and hemoglobin (Hb). Ethyl alcohol, silver nitrate, and stearic acid were, respectively, utilized as reducing agents, silver precursors, and capping agents. The color changed to cloudy from transparent, indicating that AgStNPs had been formed. AgStNP nanostructures were then distinctly integrated into the natural polymeric scaffold. To characterize the AgStNP–methacrylate polymeric monolith and the silver nanoparticles, energy-dispersive X-ray (EDX), scanning electron microscopy (SEM), and Fourier-transform infrared (FT-IR) spectroscopy were used. The results of the SEM analysis indicated that the AgStNP–methacrylate polymeric monolith’s texture was so rough in comparison with that of the methacrylate polymeric monolith, indicating that the extraction process of the monolith materials would be more efficient because of the extended surface area of the absorbent. The comparison between the FT-IR spectra of AgStNPs, the bare organic monolith, and AgStNP–methacrylate polymeric monolith confirms that the AgStNPs were immobilized on the surface of the organic monolith. The EDX profile of the built materials indicated an advanced peak of the Ag sequence which represented an Ag atom of 3.27%. The results therefore established that the AgStNPs had been successfully integrated into the monolithic materials. Extraction efficiencies of 92% and 97% were used to, respectively, recover preconcentrated Myo and Hb. An uncomplicated method is a unique approach of both fabrication and utilization of the nanosorbent to selectively isolate hemeproteins. The process can further be implemented by using other noble metals.

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