scholarly journals INVESTIGATIONS OF RESISTANCE TO SEIZING OF LASER-TEXTURED ELEMENTS

1970 ◽  
pp. 3-6
Author(s):  
Bogdan Antoszewski
Keyword(s):  
Surface Energy ◽  
Lower Surface ◽  
Texture Effect ◽  
Lower Surface Energy

The paper presents results of experiments concerning the assessment of the texture effect on scuffing resistance. The results showed that texturing  causes an increase in scuffing resistance. In addition, textures showing lower surface energy and having higher volume were found  to form surfaces more resistant to scuffing.

Molecular Dynamics Studies of Surface Nucleation and Crystal Growth of Si on SiO2 Substrates

2005 ◽  
Vol 899 ◽  
Author(s):  
Byoung-Min Lee ◽  
Hong Koo Baik ◽  
Takahide Kuranaga ◽  
Shinji Munetoh ◽  
Teruaki Motooka
Keyword(s):  
Thin Film ◽  
Molecular Dynamics ◽  
Crystal Growth ◽  
Surface Energy ◽  
Md Simulations ◽  
Lower Surface ◽  
Surface Nucleation ◽  
Lower Surface Energy ◽  
Potential Parameters ◽  
Si Thin Film

AbstractMolecular dynamics (MD) simulations of atomistic processes of nucleation and crystal growth of silicon (Si) on SiO2 substrate have been performed using the Tersoff potential based on a combination of Langevin and Newton equations. A new set of potential parameters was used to calculate the interatomic forces of Si and oxygen (O) atoms. It was found that the (111) plane of the Si nuclei formed at the surface was predominantly parallel to the surface of MD cell. The values surface energy for (100), (110), and (111) planes of Si at 77 K were calculated to be 2.27, 1.52, and 1.20 J/m2, respectively. This result suggests that, the nucleation leads to a preferred (111) orientation in the poly-Si thin film at the surface, driven by the lower surface energy.

scholarly journals Thermodynamics of manganese oxides: Sodium, potassium, and calcium birnessite and cryptomelane

2017 ◽  
Vol 114 (7) ◽  
pp. E1046-E1053 ◽  
Author(s):  
Nancy Birkner ◽  
Alexandra Navrotsky
Keyword(s):  
Surface Energy ◽  
Surface Area ◽  
Oxidation State ◽  
Manganese Oxides ◽  
Lower Surface ◽  
Surface Energies ◽  
Surface Areas ◽  
Bulk Thermodynamics ◽  
Lower Surface Energy

Manganese oxides with layer and tunnel structures occur widely in nature and inspire technological applications. Having variable compositions, these structures often are found as small particles (nanophases). This study explores, using experimental thermochemistry, the role of composition, oxidation state, structure, and surface energy in the their thermodynamic stability. The measured surface energies of cryptomelane, sodium birnessite, potassium birnessite and calcium birnessite are all significantly lower than those of binary manganese oxides (Mn3O4, Mn2O3, and MnO2), consistent with added stabilization of the layer and tunnel structures at the nanoscale. Surface energies generally decrease with decreasing average manganese oxidation state. A stabilizing enthalpy contribution arises from increasing counter-cation content. The formation of cryptomelane from birnessite in contact with aqueous solution is favored by the removal of ions from the layered phase. At large surface area, surface-energy differences make cryptomelane formation thermodynamically less favorable than birnessite formation. In contrast, at small to moderate surface areas, bulk thermodynamics and the energetics of the aqueous phase drive cryptomelane formation from birnessite, perhaps aided by oxidation-state differences. Transformation among birnessite phases of increasing surface area favors compositions with lower surface energy. These quantitative thermodynamic findings explain and support qualitative observations of phase-transformation patterns gathered from natural and synthetic manganese oxides.

Bulk and (001) Surface Properties of TiAl3 Compound

2011 ◽  
Vol 299-300 ◽  
pp. 417-421
Author(s):  
Li Wang ◽  
Jian Hong Gong ◽  
Jun Gao
Keyword(s):  
Surface Energy ◽  
Structural Relaxation ◽  
Density Functional ◽  
Dominant Role ◽  
Lower Surface ◽  
Heat Of Formation ◽  
Lattice Constants ◽  
Structural And Electronic Properties ◽  
The Stability ◽  
Lower Surface Energy

The structural and electronic properties of bulk and (001) surface of TiAl3 have been examined by the first-principles total-energy pseudopotential method based on density functional theory. The lattice constants and heat of formation of bulk TiAl3 we obtained are in good agreement with the experimental and other theoretical values. The calculated bulk properties indicates that bonding nature in TiAl3 is a combination of metallic and ionic, in which the metallic bonding become the predominate one. the strongest hybridization exist in the DO22 structure, the Al-3p and Ti-3d bonding of TiAl3 play the dominant role in hybridization. The structural relaxation and surface energy for (001) slab have been simulated to make sure the stability of slabs with different atomic layers. Compared to TiB2 (0001) slab, TiAl3 surfaces shows smaller structural relaxation and lower surface energy, furthermore, the charge redistribution of (001) slab shows almost the same characteristics as bulk TiAl3, which confirms structural stability of TiAl3 with (001) slab. This present work makes a beneficial attempt at exploring TiAl3 surface as an ab initio method for studying possible nucleation mechanism of Aluminum on it.

The Performance of Silicone Coatings Filled with Modification Carbon Nanotubes

2011 ◽  
Vol 687 ◽  
pp. 557-561
Author(s):  
Wu Gao Qiu ◽  
Zhan Ping Zhang ◽  
Yu Hong Qi ◽  
Peng Chao Zhang
Keyword(s):  
Carbon Nanotubes ◽  
Contact Angle ◽  
Surface Energy ◽  
Low Frequency ◽  
Lower Surface ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Low Surface Energy ◽  
Silicone Coatings ◽  
Lower Surface Energy

Silicones coatings were widely used owing to their excellent low surface energy and good flexibility. The structure of the modified multiple wall nanotubes (MWNTs) was tested by IR. Influence of content and sort of MWNTs on microstructures, hydrophobicity of coatings and EIS was investigated using SEM, contact angle measurement (CAM) and electrochemical workstation. The results show that various groups had embedded carbon nanotubes, the coating modified by MWNTs has much lower surface energy than that of the coating wothout modification, the coating modified by different MWNTs have diverse surface energy, and the low-frequency impedance of the coatings was not decreased as the weight of MWNTs increased.

Non-Electrical Poling in Novel Ferroelectric Polymers

1999 ◽  
Vol 600 ◽  
Author(s):  
S. Tasaka ◽  
O. Furutani ◽  
N. Inagaki
Keyword(s):  
Surface Energy ◽  
Room Temperature ◽  
Remanent Polarization ◽  
Lower Surface ◽  
Energy Difference ◽  
Bottom Surface ◽  
Ferroelectric Polymers ◽  
Ptfe Film ◽  
Dipole Glass ◽  
Lower Surface Energy

AbstractNon-electrical poling was proposed in novel ferroelectric polymers including such as polythioureas, polycyanophenylenesulfides, and polyvinyfluorides. This poling method utilizing the cooperativity of molecular dipoles can be called “surface energy poling” and takes agvantage of the energy difference inthe top and bottom surface of apolar aggregate (dipole glass) to form a remanent polarization. A ferroelectric polymer film sandwiched between a metal with higher surface energy and PTFE film with lower surface energy were heated to Tp=Tc (glass tramsition temperature or ferroelectric transition) × 1.2 and cooled slowly to room temperature. In the thin films less than 10μm, we observed the remanent polarization which gives a large pyroand piezo-electric constant as well as that obtained by electrical poling. This poling is effective for homogenious structures such as amophous ferroelectric polymers.

Control of Primary Particle Size and the Onset of Aggregate Formation: The Effect of Energy Release in Nanoparticle Collision and Coalescence Processes

2002 ◽  
Vol 731 ◽  
Author(s):  
Karl E.J. Lehtinen ◽  
Michael R. Zachariah
Keyword(s):  
Heat Transfer ◽  
Heat Release ◽  
Energy Release ◽  
Primary Particle ◽  
High Volume ◽  
Lower Surface ◽  
Aggregate Formation ◽  
Gas Temperature ◽  
Insufficient Time ◽  
Lower Surface Energy

AbstractDuring coalescence, the surface area of the particle decreases, resulting in a heat release associated with the resulting lower surface energy. In a growth process particle heating competes with heat transfer by conduction to the cooler carrier gas and radiation. This temperature increase can be extremely important and should be accounted for when modeling collision/coalescence processes. The heat release associated with particle coalescence may reduce the coalescence time by as much as a few orders of magnitude. In addition, under some conditions there is insufficient time for the particles to cool to the gas temperature before another collision event takes place. It is shown that accounting for energy release and heat transfer effects have a dramatic effect on primary particle formation and the onset of aggregate formation. The results of the work indicate that to grow the largest primary particles one should operate at low pressures and high volume loadings.

scholarly journals Effect of Polymer Demixed Nanotopographies on Bacterial Adhesion and Biofilm Formation

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1921
Author(s):  
George Fleming ◽  
Jenny Aveyard ◽  
Joanne L. Fothergill ◽  
Fiona McBride ◽  
Rasmita Raval ◽  
...  
Keyword(s):  
Lower Surface ◽  
Surface Feature ◽  
Polymer Interface ◽  
Cell Counts ◽  
Binary Polymer ◽  
Lower Solubility ◽  
Specific Morphology ◽  
Discrete Surface ◽  
Global Threat ◽  
Lower Surface Energy

As the current global threat of antimicrobial resistance (AMR) persists, developing alternatives to antibiotics that are less susceptible to resistance is becoming an urgent necessity. Recent advances in biomaterials have allowed for the development and fabrication of materials with discrete surface nanotopographies that can deter bacteria from adhering to their surface. Using binary polymer blends of polystyrene (PS), poly(methyl methacrylate) (PMMA) and polycaprolactone (PCL) and varying their relative concentrations, PS/PCL, PS/PMMA and PCL/PMMA polymer demixed thin films were developed with nanoisland, nanoribbon and nanopit topographies. In the PS/PCL system, PS segregates to the air-polymer interface, with the lower solubility PCL preferring the substrate-polymer interface. In the PS/PMMA and PCL/PMMA systems, PMMA prefers the air-polymer interface due to its greater solubility and lower surface energy. The anti-adhesion efficacy of the demixed films were tested against Pseudomonas aeruginosa (PA14). PS/PCL and PCL/PMMA demixed films showed a significant reduction in cell counts adhered on their surfaces compared to pure polymer control films, while no reduction was observed in the counts adhered on PS/PMMA demixed films. While the specific morphology did not affect the adhesion, a relationship between bacterial cell and topographical surface feature size was apparent. If the surface feature was smaller than the cell, then an anti-adhesion effect was observed; if the surface feature was larger than the cell, then the bacteria preferred to adhere.

scholarly journals Improving fouling resistance of seawater desalination membranes via surface modification

2013 ◽  
Vol 3 (3) ◽  
pp. 217-223
Author(s):  
Jong-Min Lee ◽  
Hyun-Woong Lee ◽  
Yeo-Jin Kim ◽  
Hyung-Gyu Park ◽  
Sung-Pyo Hong ◽  
...  
Keyword(s):  
Surface Modification ◽  
Surface Energy ◽  
Membrane Surface ◽  
Cross Flow ◽  
Lower Surface ◽  
Fouling Resistance ◽  
Surface Charges ◽  
Cross Flow Filtration ◽  
Modified Membrane ◽  
Surface Modified

A commercial polyamide seawater reverse osmosis membrane (Woongjin Chemical CSM) was surface-modified with fluoro-compounds. The effect of this surface modification on both water and NaCl permeability before and after organic fouling was investigated. The structural and electrical characteristics of the membrane surface were measured using atomic force microscopy and electrokinetic analysis respectively. When modified, the membrane surface showed only slight changes to the surface roughness and surface charges. The modified membrane also showed highly improved fouling resistance during cross-flow filtration of characteristic seawater organic foulants (humic acid and sodium alginate). Contact angle analysis using the Owens-Wendt theory was used to calculate the surface energy of the modified membrane. Lower surface energy of the modified membrane was identified as the key factor in the improved fouling resistance of the membranes.

Relationship Between Platelet Adhesion And Free Energies At Solid-Liquid Interfaces

1981 ◽  
Author(s):  
Donald J L McIver ◽  
Samuel Schürch
Keyword(s):  
Thrombus Formation ◽  
Lower Surface ◽  
Liquid Interfaces ◽  
Free Energies ◽  
Surface Wetting ◽  
Interfacial Energies ◽  
Synthetic Coating ◽  
Foreign Surface ◽  
Solid Liquid ◽  
Lower Surface Energy

Surface induced thrombosis remains an obstacle to extra-corpeal circulation and invasive investigation and therapy of the cardiovascular system. Although the molecular details of the blood-foreign surface interaction remain incompletely understood, from a thermodynamic viewpoint, thrombosis can only occur if thrombus formation lowers the free energy of the blood-surface system. We have recently reported a method of estimating surface free energies under physiological conditions from measurements of surface wetting by polar hydrophobic fluids. Here we report a correlation between interfacial energies and platelet retention on natural and artificial surfaces, and the effects on platelet retention of a synthetic coating developed in an attempt to mimic the thromboresistance of healthy endothelium. This coating has a lower surface energy than the artery and it appears to be equally thromboresistant.

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