scholarly journals Physio-chemical hydrodynamic mechanism underlying the formation of thin adsorbed boundary films

2012 ◽  
Vol 156 ◽  
pp. 123 ◽  
Author(s):  
W. W. F. Chong ◽  
M. Teodorescu ◽  
H. Rahnejat
Keyword(s):  
Hydrodynamic Mechanism ◽  
Boundary Films

TEM Studies of Grain Boundary Films in Si3N4 Ceramics

1991 ◽  
Vol 49 ◽  
pp. 930-931
Author(s):  
H.-J. Kleebe ◽  
J.S. Vetrano ◽  
J. Bruley ◽  
M. Rühle
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Hot Isostatic Pressing ◽  
Amorphous Film ◽  
Liquid Phase Sintering ◽  
Second Phase ◽  
High Temperature Mechanical Properties ◽  
Triple Points ◽  
Boundary Films

It is expected that silicon nitride based ceramics will be used as high-temperature structural components. Though much progress has been made in both processing techniques and microstructural control, the mechanical properties required have not yet been achieved. It is thought that the high-temperature mechanical properties of Si3N4 are limited largely by the secondary glassy phases present at triple points. These are due to various oxide additives used to promote liquid-phase sintering. Therefore, many attempts have been performed to crystallize these second phase glassy pockets in order to improve high temperature properties. In addition to the glassy or crystallized second phases at triple points a thin amorphous film exists at two-grain junctions. This thin film is found even in silicon nitride formed by hot isostatic pressing (HIPing) without additives. It has been proposed by Clarke that an amorphous film can exist at two-grain junctions with an equilibrium thickness.

Grain Boundary Films in Boron Steels

JOM ◽  
1953 ◽  
Vol 5 (3) ◽  
pp. 445-446
Author(s):  
J. W. Spretnak ◽  
Rudolph Speiser
Keyword(s):  
Grain Boundary ◽  
Boundary Films ◽  
Boron Steels

Note. Vacuum impregnation of banana (Musa acuminata cv. giant cavendish) / Nota. Impregnación a vacío de banana (Musa acuminata cv. giant cavendish

1998 ◽  
Vol 4 (2) ◽  
pp. 127-131 ◽  
Author(s):  
R. Sousa ◽  
D. Salvatori ◽  
A. Andrés ◽  
P. Fito
Keyword(s):  
Structural Changes ◽  
Musa Acuminata ◽  
Diameter Ratio ◽  
Dynamic Mechanism ◽  
Vacuum Impregnation ◽  
Local Market ◽  
Relaxation Phenomena ◽  
Pressure Gradients ◽  
Hydrodynamic Mechanism

Vacuum impregnation of banana was analysed by a hydrodynamic mechanism to determine effec tive porosity ( ∈e). In the initial experiments, the influence of the ripening degree and cut was deter mined without taking into account sample deformations caused by the pressure gradients; in these cases ∈ e decreased as maturity progressed. Important structural changes were observed 2-4 days after the bananas were purchased from the local market, probably due to the climacteric charac teristic of the product. Other experiments were carried out to analyse the coupling of the hydro dynamic mechanism (HDM) with deformation-relaxation phenomena (DRP) by varying the time of treatment; ε e values determined by this procedure were approximately 10.1% and significant deformation values in the vacuum step (γ e = 3.6%) were observed. The height/diameter ratio also seemed to influence the behaviour of the product to the HDM-DRP action. The most impregnated samples were the ones with a height half that of the banana diameter.

ChemInform Abstract: Dopant Distribution in Grain-Boundary Films in Calcia-Doped Silicon Nitride Ceramics.

ChemInform ◽  
2010 ◽  
Vol 30 (13) ◽  
pp. no-no
Author(s):  
Hui Gu ◽  
Xiaoqing Pan ◽  
Rowland M. Cannon ◽  
Manfred Ruehle
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Dopant Distribution ◽  
Nitride Ceramics ◽  
Doped Silicon ◽  
Boundary Films

High-resolution Electron Microscopy Observation of Grain-boundary Films in Superplastically Deformed Silicon Nitride

2000 ◽  
Vol 15 (7) ◽  
pp. 1551-1555 ◽  
Author(s):  
Guo-Dong Zhan ◽  
Mamoru Mitomo ◽  
Yuichi Ikuhara ◽  
Taketo Sakuma
Keyword(s):  
Electron Microscopy ◽  
Silicon Nitride ◽  
High Resolution ◽  
Grain Boundary ◽  
Applied Stress ◽  
Thickness Distribution ◽  
High Resolution Electron Microscopy ◽  
Stress Axis ◽  
Resolution Electron ◽  
Boundary Films

The thickness distribution of grain-boundary films during the superplastic deformation of fine-grained β–silicon nitride was investigated by high-resolution electron microscopy. In particular, grain-boundary thickness was considered with respect to the stress axis in two orientations; namely, parallel and perpendicular to the direction of applied stress. The results showed that the thickness distribution in boundaries perpendicular to the direction of applied stress was unimodal, whereas in parallel boundaries it was bimodal. Moreover, it was found that the majority of film-free boundaries were parallel to the direction of applied stress in the extremely deformed sample. The variation in spacing reflects distribution of stresses within the material due to irregular shape of the grains and the existence of percolating load-bearing paths through the microstructure.

Simulation of Gas Transportation in Radial Shaft Seal With Model Surfaces

2010 ◽  
Author(s):  
H. Mizuta ◽  
S. Nakaoka ◽  
Y. Sato ◽  
J. Sugimura
Keyword(s):  
Gas Flow ◽  
Analytical Study ◽  
Axial Flow ◽  
Liquid Interfaces ◽  
Dissolved Gas ◽  
Shaft Seal ◽  
Solubility Coefficient ◽  
Lubricant Flow ◽  
Flow Through ◽  
Boundary Films

This paper describes an analytical study on gas transportation in radial shaft seal. A model is constructed in which seal surfaces with sinusoidal roughness, lubricant flow at the seal lip with gaseous cavity, dissolution of gas into and release of gas from the lubricant across double boundary films at gas-liquid interfaces, and convection of dissolved gas in the lubricant flow are considered. Polyalphaolefin as a lubricant, and helium, argon and carbon dioxide are assumed. The results demonstrate that the axial flow induced by surface roughness carries the gas, and that the gas flow through the lubricant film is proportional to the gas solubility coefficient, and the circumferential speed of the shaft, which agrees with the experimental finding for actual seals. The dependence of the gas flow on the axial flow of the oil and that on the boundary films are discussed.

Grain boundary films in Al–Zn alloys after high pressure torsion

2014 ◽  
Vol 70 ◽  
pp. 59-62 ◽  
Author(s):  
B.B. Straumal ◽  
X. Sauvage ◽  
B. Baretzky ◽  
A.A. Mazilkin ◽  
R.Z. Valiev
Keyword(s):  
High Pressure ◽  
Grain Boundary ◽  
High Pressure Torsion ◽  
Boundary Films ◽  
Zn Alloys
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