scholarly journals The Effects of Ammonium Polyacrylate and Diammonium Citrate as Base and Acid Dispersion Agents on Yttria-Stabilized Zirconia (3Y-TZP) Dispersion Properties

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Pestaria Sinaga ◽  
Sung-Hwan Bae
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Ph Value ◽  
Aqueous Suspension ◽  
Low Ph ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Attrition Mill ◽  
Shear Rates ◽  
Dispersion Properties

Stable slurries in dispersions of 3Y-TZP in aqueous suspension with the addition of different concentrations of dispersants such as ammonium polyacrylate (APA) and diammonium citrate (DAC) were investigated. The dispersion properties were investigated by measuring the particle size, zeta potential, sedimentation, and viscosity as a function of the wt.% of the dispersant. Both dispersant agents were attached to the 3Y-TZP surface by the carboxylic group, as shown by the FTIR results. The addition of dispersants was found to produce more dispersed and stabilized aqueous suspension. As shown the viscosity result, that there is no being viscosity peak has been occurring and viscosity going decrease as the shear rates increasing which mean that the suspension has shear thinning behavior and there is no agglomeration as the shear rate is increased. It was determined that 3.5 wt.% of DAC and APA produced the best and most stable slurry; when 3.5 wt.% of DAC and APA was added, the zeta potential showed the largest value in the monodisperse condition. The low pH value of DAC has obtained the higher zeta potential value than APA, which was assumed due to low pH of DAC suspension. At low pH, the adsorption of the adsorbate will occur in a flat adsorbed, while at higher pH the polyelectrolyte will dangle into solution, thus reducing electrostatic repulsion as it is found in the case of APA addition. In this condition, the particle size was decreased to the lower value and the slurry’s stability was obtained with the lowest sedimentation height after the sedimentation test for 30 days. The sample was milled in an attrition mill at 1,000 rpm for four hours.

pH Effect on Electrophoretic Deposition in Non-Aqueous Suspensions and Sintering of YSZ Coatings

2009 ◽  
Vol 412 ◽  
pp. 165-170
Author(s):  
Hui Xu ◽  
Ian P. Shapiro ◽  
Ping Xiao
Keyword(s):  
Zeta Potential ◽  
Ph Value ◽  
Ph Effect ◽  
Yttria Stabilized Zirconia ◽  
Particle Suspension ◽  
Suspension Stability ◽  
Particle Coagulation ◽  
Micro Hardness ◽  
Stabilized Zirconia ◽  
Suspension Ph

Yttria stabilized zirconia (YSZ) particle suspension in acetylacetone (ACAC) was deposited onto Fecralloy substrates by using EPD and then constrained sintered at 1200°C. Before EPD, the operational pH value of the suspension was adjusted with addition of acetic acid or base triethanolamine (TEA). The effect of suspension pH on the deposition of EPD coatings was studied with respect to the suspension stability, coating density and microstructure. Results showed that the zeta potential decreased to close to zero with the increase of pH value from 4.4 to 7.4, then increased with further increase of the pH. This ‘U’ shape zeta potential-pH relationship was probably resulted from the adsorption of TEA. This reduced the degree of particle coagulation and increased the packing density of the EPD coatings; therefore, promoted the sequent sintering of coatings which was evaluated by micro-hardness.

scholarly journals Identification of tetragonal and cubic structures of zirconia using synchrotron x-radiation source

1991 ◽  
Vol 6 (6) ◽  
pp. 1287-1292 ◽  
Author(s):  
Ram Srinivasan ◽  
Robert J. De Angelis ◽  
Gene Ice ◽  
Burtron H. Davis
Keyword(s):  
Particle Size ◽  
Radiation Source ◽  
Sol Gel ◽  
Yttria Stabilized Zirconia ◽  
Tetragonal Structure ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Synchrotron Source ◽  
Three Samples

X-ray diffraction from a synchrotron source was employed in an attempt to identify the crystal structures in zirconia ceramics produced by the sol-gel method. The particles of chemically precipitated zirconia, after calcination below 600 °C, are very fine, and have a diffracting particle size in the range of 7–15 nm. As the tetragonal and cubic structures of zirconia have similar lattice parameters, it is difficult to distinguish between the two. The tetragonal structure can be identified only by the characteristic splittings of the Bragg profiles from the “c” index planes. However, these split Bragg peaks from the tetragonal phase in zirconia overlap with one another due to particle size broadening. In order to distinguish between the tetragonal and cubic structures of zirconia, three samples were studied using synchrotron radiation source. The results indicated that a sample containing 13 mol% yttria-stabilized zirconia possessed the cubic structure with a0 = 0.51420 ± 0.00012 nm. A sample containing 6.5 mol% yttria stabilized zirconia was found to consist of a cubic phase with a0 = 0.51430 ± 0.00008 nm. Finally, a sample which was precipitated from a pH 13.5 solution was observed to have the tetragonal structure with a0 = 0.51441 ± 0.00085 nm and c0 = 0.51902 ± 0.00086.

Dynamic response of graphene and yttria-stabilized zirconia (YSZ) composites

2019 ◽  
Author(s):  
Christopher R. Johnson ◽  
John P. Borg
Keyword(s):  
Particle Size ◽  
Dynamic Behavior ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Weight Percentage ◽  
Micrometer Particle ◽  
Graphene Content ◽  
Morphological Differences ◽  
Hugoniot Curves ◽  
Impact Experiments

Abstract A series of dynamic compaction studies were performed on yttria-stabilized zirconia (YSZ) and graphene composites using uniaxial flyer plate impact experiments. Studies aimed to characterize variation in dynamic behavior with respect to morphological differences for eight powdered YSZ and graphene compositions. Parameters of interest included YSZ particle size (nanometer or micrometer) and added graphene content (graphene weight percentage: 0%, 1%, 3%, 5%). Experiments were performed over impact velocities ranging between 315 and 586 m/s, resulting in pressures between 0.8 and 2.8 GPa. Hugoniot states measured appear to exhibit dependence on particle size and graphene content. Shock velocities tended to increase with graphene content and were generally larger in magnitude for the micrometer particle size YSZ. Compacted densities tended to increase as graphene content was increased and were generally larger in magnitude for the micrometer particle size YSZ samples. Resulting Hugoniot curves are compared and summarized to convey the dynamic behavior of the specimens.

Homogenization and Melt-Emulsification Techniques for Ibuprofen Particle Size Reduction: Effect of Tween 80 & Sonication

2012 ◽  
Vol 229-231 ◽  
pp. 179-182
Author(s):  
Sarun Tuntarawongsa ◽  
Thawatchai Phaechamud
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Ph Value ◽  
Tween 80 ◽  
Size Reduction ◽  
Particle Size Reduction ◽  
Reduction Effect ◽  
Emulsification Process ◽  
Suitable Process

Ibuprofen suspensions were prepared by simple homogenization with melt-emulsification process. Tween 80 was used as stabilizer. The homogenized suspensions were evaluated and compared with melt emulsificated suspension. The pH value and rheology behavior were not difference. The viscosity was very low. Zeta potential was -10 to -25 mV. In this study, the suitable process to minimize particle size of ibuprofen suspension was melt emulsification follow by sonication. This process could be developed to obtain nanosuspension by adjust sonication process and improved formulation to obtain suitable nanosuspension.

scholarly journals Formulation and Investigation of Lacidipine as a Nanoemulsions

2020 ◽  
Vol 29 (1) ◽  
pp. 41-54
Author(s):  
Rajaa A. Dahash ◽  
Nawal A. Rajab
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Dissolution Rate ◽  
Thermodynamic Stability ◽  
Water Solubility ◽  
Ph Value ◽  
Pharmaceutical Preparations ◽  
Light Transmittance ◽  
Drug Content

Many pharmaceutical molecules have solubility problems that until yet consist a hurdle that restricts their use in the pharmaceutical preparations. Lacidipine (LCDP) is a calcium-channel blocker with low aqueous solubility and bioavailability.         Lipid dosage forms are attractive delivery systems for such hydrophobic drug molecules. Nanoemulsion (NE)  is one of the popular methods that has been used to solve the solubility problems of many drugs. LCDP was formulated as a NE utilizing triacetin as an oil phase, tween 80 and tween 60 as a surfactant and ethanol as a co-surfactant. Nine formulas were prepared, and different tests performed to ensure the stability of the NEs, such as thermodynamic stability, particle size, Polydispersity index, zeta potential, dye solubility test, dilution test, drug content test and in-vitro drug release. Results of characterization showed that LCDP NE (F-5) with (oil: Smix (3:1):DDW (10:60:30)) ratio was selected as a best formula, since it have excellent thermodynamic stability with a particle size of 13.42, low PDI 0.234 , zeta potential (-14.5mV), efficient electrical    conductivity  0.241ms/cm , good pH value (5.9), good percent of light transmittance (99.10%) , with  acceptable viscosity , higher percent of drug content (99.14%) and complete release of the drug after (30 min.) with significantly higher (P<0.05)   dissolution rate in comparison with pure drug powder.      From the results obtained NE was found to be an efficient method to enhance the solubility and dissolution rate of drugs that have poor water solubility (lipophilic drugs).    

scholarly journals Influence of pH and ionic strength on the aggregation behaviors of xylan rich hemicelluloses with alkaline lignins

BioResources ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. 7608-7622
Author(s):  
Guichun Hu ◽  
Jinguang Hu ◽  
Honglei Chen ◽  
Shunxi Song ◽  
Fuqiang Chu
Keyword(s):  
Particle Size ◽  
Self Assembly ◽  
Main Chain ◽  
Ph Value ◽  
Low Ph ◽  
Ph Values ◽  
Wide Range ◽  
Nacl Concentration ◽  
Aggregation Behaviors ◽  
Influence Of Ph

The evolution of xylan-rich hemicelluloses (XH) aggregation behaviors in the presence of alkaline lignins (AL) under a wide range of pH values and NaCl concentration were investigated via dynamic light scattering and turbidity measurements. XH isolated from wheat straw contain a xylose backbone with arabinose side chains and a small amount of phenol groups. XH tend to aggregate in solution due to their low ratio of arabinose to xylose and hydrophobic phenol groups. AL interact with XH through the phenol groups bonded to the hemicellulose main chain to form an AL-XH complex. As the pH value decreases, the particle size and turbidity of AL, XH and their bonded complex all increase. The size of the AL-XH complex agglomerate is greater than the size of a XH at the same pH value, which indicates that the self-assembly of lignin molecules initiate the aggregation of XH. The particle size and turbidity of XH and AL-XH complexes increase as the XH concentration increase. At low pH values, e.g., 6.0, the particle size of the AL-XH complex more obviously increases compared to the XH particles. The size and turbidity of the AL, XH, and AL-XH complex agglomerates increased as the NaCl concentration increased.

Stability of nano-sized titanium dioxide in an aqueous environment: effects of pH, dissolved organic matter and divalent cations

2013 ◽  
Vol 68 (2) ◽  
pp. 276-282 ◽  
Author(s):  
X. N. Yang ◽  
F. Y. Cui
Keyword(s):  
Particle Size ◽  
Titanium Dioxide ◽  
Organic Matter ◽  
Zeta Potential ◽  
Dissolved Organic Matter ◽  
Ph Value ◽  
Divalent Cations ◽  
Aqueous Environment ◽  
Nano Tio2 ◽  
The Stability

Nano-sized titanium dioxide in the aquatic environment has a potential impact on the environment and human health. In this study, the impact of pH value, dissolved organic matter (DOM) and divalent cations (Ca2+) on the stability of titanium dioxide nanoparticles (nano-TiO2) in an aqueous environment was investigated in batch tests. The results showed that the particle size of nano-TiO2 was not sensitive to pH value but was inversely proportional to zeta potential. The nano-TiO2 becomes more stable with surface zeta potential, accompanied by small particle size and high dispersion. In the presence of DOM, the particle size was smaller and the stability of nano-TiO2 could be enhanced. This might be a synergistic effect of the ligand exchange and electrostatic force. Particle size increased with the addition of Ca2+ and the stability decreased.

Microcapsule Particle Size and Size Distribution and its Influencing Factors

2013 ◽  
Vol 746 ◽  
pp. 118-122 ◽  
Author(s):  
Zhao Hui Zhen ◽  
Zheng Shun Wang
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Influencing Factors ◽  
Large Particle ◽  
Ph Value ◽  
Low Ph ◽  
Formaldehyde Resin ◽  
Melamine Formaldehyde ◽  
Large Particle Size ◽  
Rough Surface Morphology

The paper studied the microcapsule particle size, size distribution and its influencing factors with melamine formaldehyde resin (MF-resin) as wall and CVL as core. The results indicated that the microcapsules mean particle size decreased, size distribution became narrow with the increase of emulsifying time and shear rate. Low pH value would make the microcapsules have rough surface morphology and large particle size.

Interlaboratory comparison for the measurement of particle size and zeta potential of silica nanoparticles in an aqueous suspension

2011 ◽  
Vol 13 (12) ◽  
pp. 7317-7329 ◽  
Author(s):  
Andrée Lamberty ◽  
Katrin Franks ◽  
Adelina Braun ◽  
Vikram Kestens ◽  
Gert Roebben ◽  
...  
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Silica Nanoparticles ◽  
Interlaboratory Comparison ◽  
Aqueous Suspension
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