scholarly journals Viscosity model for fully liquid silicate melt

2012 ◽  
Vol 48 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Guo-Hua Zhang ◽  
Kuo-Chih Chou
Keyword(s):  
Activation Energy ◽  
Bond Strength ◽  
Size Effect ◽  
Interaction Force ◽  
Silicate Melt ◽  
Viscosity Model ◽  
Nonlinear Variation ◽  
Liquid Silicate ◽  
Lower Viscosity ◽  
Two Factors

A model for estimating the viscosity of silicate melt as derived in our previous paper is extended to the system containing MgO, CaO, SrO, BaO, Li2O, Na2O, K2O, which can express the nonlinear variation of activation energy of viscosity with the composition. It is found that the optimized parameters of model which characterize the deforming ability of bonds around non-bridging oxygen decrease with increasing the bond strength of M-O bond expressed by I=2Q/RMz+ + rO2-)2 (where Q is the valence of cation M; r is the radius). It is pointed out that viscosity is not only determined by the bond strength, but also by the radius of cation which is defined as the size effect. The radius of cation plays paradox roles in the two factors: smaller radius leads to a stronger bond, thus a higher viscosity; while cations with smaller radius are easier to diffuse when neglecting the interaction force, thus a lower viscosity will be.

Effects of Microstructure on the Electrical Conductivity of SrCo0.8Fe0. 2O3_δ

1999 ◽  
Vol 575 ◽  
Author(s):  
K. Zhang ◽  
M. Miranova ◽  
Y. L. Yang ◽  
A. J. Jacobson ◽  
K. Salama
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Grain Size ◽  
Size Effect ◽  
Temperature Region ◽  
Grain Size Effect ◽  
Average Grain Size ◽  
Lower Temperature ◽  
Lower Temperature Region ◽  
Test Temperature Range

ABSTRACTThe effect of microstructure on the electrical conductivity of SrCO0.8Fe0.2O3_δ (SCFO) was investigated in air using a four-point dc method. In the test temperature range of 200 to 900 °C, the electrical conductivity of this material was observed to increase with the increase of the average grain size in the lower temperature region where the conductivity increases with the increase of the temperature. The activation energy is decreased with the increase of the grain size in this region, 0.04 ± 0.004 ev for 4.1μm sample and 0.01 ± 0.001 ev for 14.8 μm sample. When temperature is further increased, the conductivity of this material decreases with the increase of the temperature, and the grain size effect becomes less noticeable.

scholarly journals Bond strength of composite resin containing biomaterial S-PRG to eroded dentin

2017 ◽  
Vol 16 ◽  
pp. 1-10
Author(s):  
Alessandra Sanchez Coelho Lourenço ◽  
Ana Paula Almeida Ayres ◽  
Taís Fonseca Mantilla ◽  
Marcelo Giannini ◽  
Patricia Moreira de Freitas
Keyword(s):  
Bond Strength ◽  
Composite Resin ◽  
Optical Microscope ◽  
Fracture Pattern ◽  
Supersaturated Solution ◽  
Solution Ph ◽  
Microtensile Bond Strength ◽  
Significant Difference ◽  
Restorative Materials ◽  
Two Factors

Aim: To evaluate the bond strength of composite resin containing or not biomaterial (S-PRG) to sound/eroded dentine. Methods: Occlusal dentin of 30 human molars (n=15) had half of its surface kept uneroded, while on the other half an erosive lesion was produced by cycling in citric acid (pH 2.3) and supersaturated solution (pH 7.0). On both eroded (ED) and non-eroded (SD) substrates, two restorative systems (containing or not S-PRG) were tested. Composite resin cylinders were built and, after storage in water (24h), were submitted to bond strength test. The analysis of the fracture pattern was performed under an optical microscope (40x). The obtained values of bond strength (MPa) were submitted to ANOVA (two factors) and Tukey multiple comparisons tests (p<0.05). Results: According to the results, there was difference between substrates (<0.001) and restorative materials (p=0.002) evaluated. For the microtensile bond strength, the values obtained were: SDNB (47.6±12.2 MPa), SDWB (34.1±15.8 MPa), EDNB (31.1±8.3 MPa) and EDWB (15.5±13.6 MPa), revealing a statistically significant difference in the evaluated substrates and restorative materials. Conclusion: Bond strength of eroded substrate is inferior to the sound substrate and the restorative system containing S-PRG biomaterial influences negatively the results of bonding to sound/eroded dentin.

Measuring intermolecular binding forces with the Atomic-Force Microscope: The magnetic jump method

1994 ◽  
Vol 52 ◽  
pp. 1054-1055
Author(s):  
J. H. Hoh ◽  
P. E. Hillner ◽  
P. K. Hansma
Keyword(s):  
Bond Strength ◽  
Atomic Force Microscope ◽  
Interaction Force ◽  
Intermolecular Forces ◽  
Atomic Force ◽  
Novel Approach ◽  
Binding Forces ◽  
Afm Cantilever ◽  
Paramagnetic Beads ◽  
Direct Readout

The atomic-force microscope (AFM) can measure forces between atoms and molecules with a sensitivity of <10−12 N. By coating the AFM tip with specific molecules the types of interactions that can be examined will be greatly extended. Recently tips with biotin attached have been used to probe surfaces coated with avidin or streptavidin, to measure the respective bond strength.We have developed a novel approach to measuring intermolecular forces with the AFM that employs paramagnetic beads coated with one of the molecules to be studied. Beads are incubated with a surface coated with the second molecule, and allowed to form a specific bond. A small magnet glued to an AFM cantilever is then advanced toward the bead until the bond with between the two molecules breaks and the bead “jumps” to the magnet. The deflection of the cantilever provides a direct readout of the interaction force at the “jump,” and thereby a measure of the bond strength.

H2 DISSOCIATION ON A Pt OVERLAYER ON Ni(111)

1997 ◽  
Vol 04 (01) ◽  
pp. 45-52 ◽  
Author(s):  
N. J. CASTELLANI ◽  
C. MEHADJI ◽  
P. LÉGARÉ
Keyword(s):  
Activation Energy ◽  
Electronic Properties ◽  
Cluster Model ◽  
Molecular Adsorption ◽  
Hydrogen Atoms ◽  
Coordination Sites ◽  
Extended Hückel ◽  
Two Factors ◽  
Extended Hückel Calculations ◽  
Dissociated State

The chemisorption of hydrogen atoms and the H 2 molecule was studied by the use of extended Hückel calculations in a cluster model to simulate a Pt (111) surface and a Pt overlayer in epitaxy on Ni (111). The result of epitaxy on the chemisorptive properties of Pt is to disfavor the H atom adsorption on the higher coordination sites, and to increase the activation energy of H 2 dissociation. This is due to two factors. First, the Pt – Pt distance shortening increases the repulsion produced by the Pt neighbors on the adatoms. Second, the study of the local electronic properties of the chemisorption site shows that the pure Pt surface tends to chemisorb the H 2 molecule in the dissociated state whereas the Pt/Ni system would favor the molecular adsorption only.

scholarly journals Effect of Bio-Oil Species on Rheological Behaviors and Gasification Characteristics of Coal Bio-Oil Slurry Fuels

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1045
Author(s):  
Ping Feng ◽  
Jie Li ◽  
Jinyu Wang ◽  
Huan Wang ◽  
Zhiqiang Xu
Keyword(s):  
Activation Energy ◽  
Calorific Value ◽  
Transportation Cost ◽  
Gas Production ◽  
Rheological Behaviors ◽  
Wood Pyrolysis ◽  
Lower Viscosity ◽  
Bio Oil ◽  
Pyroligneous Acid ◽  
Green Fuels

Bio-oil is a promising fuel as one of the main products from biomass fast pyrolysis for improving energy density and reducing transportation cost, but high acidity and low calorific value limit its direct application. It can be used to prepare coal bio-oil slurry as partial green fuels for potential feeds for synthesis gas production via gasification with the advantages over traditional coal-water slurries of calorific values and being additives-free. In the present work, three bio-oils were blended with lignite to prepare slurry fuels for the investigation of the effect of bio-oil species on rheological behaviors and gasification characteristics of coal bio-oil slurry fuels. Results show that slurry prepared with bio-oil from fruit tree pyrolysis is highly viscous and has higher activation energy in gasification. Slurries prepared with bio-oils from straw pyrolysis and pyroligneous acid from wood pyrolysis exhibited an acceptably lower viscosity, and the gasification temperatures were lower than for coal. The activation energy decreased by 15.98 KJ/mol and 2.77 KJ/mol, respectively, which indicates these bio-oils are more suitable with lignite for slurries preparation.

Effect of Section Size on Notch Strength

1966 ◽  
Vol 88 (3) ◽  
pp. 675-681 ◽  
Author(s):  
V. Weiss ◽  
G. Schaeffer ◽  
J. Fehling
Keyword(s):  
Stress Concentration ◽  
Size Effect ◽  
Notch Root ◽  
Geometrical Parameters ◽  
Notched Specimens ◽  
Notch Root Radius ◽  
Section Size ◽  
Two Factors ◽  
Notch Strength ◽  
Experimental Scatter

The effect of section size on the room-temperature notch strength of H-11 steel, 2014-T6 and 7075-T6 aluminum alloys, and Plexiglas was investigated in three different series of notched cylindrical tensile specimens and notched rectangular bend specimens. The three test series permit the separation of the influences of the geometrical parameters, which determine the stress field near the base of the notch, on the notch strength as the size of the specimen increases. The notch strength decreases with increasing size for all series investigated. The decrease in strength is most pronounced for the sharp machine-notched and fatigue-cracked specimens but it is also observed, to a much smaller degree, in the other series of notched specimens for all materials. An analysis of the results of this study indicates that the loss in strength with increasing section size is due to at least two factors: An increase in stress concentration factor and an increase in critically stressed volume with increasing size. With a superposition of stress concentration and volumetric effects, a loss in strength with increasing size greater than that predicted by existing fracture concepts for a brittle material may be anticipated and was actually observed for sharply notched H-11 steel specimens. Insight into the size effect and experimental scatter observed in notched specimens of real materials is gained from a consideration of the behavior of a model of an inhomogeneous material in the presence of external notches. The constant-fracture stress concept applied to this model yields a size-effect prediction on notch strength and an expression for experimental scatter in terms of the interflow spacing and the notch root radius.

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