Impression creep of a thin film by vacancy diffusion. II. Cylindrical punch

1993 ◽  
Vol 74 (7) ◽  
pp. 4390-4397 ◽  
Author(s):  
Fuqian Yang ◽  
J. C. M. Li
Keyword(s):  
Thin Film ◽  
Vacancy Diffusion ◽  
Impression Creep ◽  
Cylindrical Punch

Impression creep of a thin film by vacancy diffusion. I. Straight punch

1993 ◽  
Vol 74 (7) ◽  
pp. 4382-4389 ◽  
Author(s):  
Fuqian Yang ◽  
J. C. M. Li
Keyword(s):  
Thin Film ◽  
Vacancy Diffusion ◽  
Impression Creep

Impression creep of a viscous layer

2001 ◽  
Vol 16 (9) ◽  
pp. 2709-2715 ◽  
Author(s):  
Hong Chen ◽  
J. C. M. Li
Keyword(s):  
Thin Film ◽  
Boundary Conditions ◽  
Finite Thickness ◽  
Slip Boundary Condition ◽  
Auxiliary Function ◽  
Fredholm Integral Equations ◽  
Impression Creep ◽  
Viscous Layer ◽  
Slip Boundary ◽  
Cylindrical Punch

Impression creep of a flat-ended cylindrical punch pushed into a viscous layer overlaid on a rigid substrate is analyzed. The method developed here permits us to relate the impression velocity to the punching stress in terms of an auxiliary function, which represents the solution of a set of Fredholm integral equations with a continuous symmetrical kernel. By a series of numerical analysis, the influence of the boundary conditions and the effect of the thickness of the layer on the impression velocity are obtained. For infinite thickness (i.e., h/a →∞, where h is the thickness of the layer and a is the radius of the punch), the impression creep is independent of the stick or slip boundary condition at the indenter/layer interface. For finite thickness such as h/a = 20, the boundary conditions have about 5% effect on the impression velocity. For a thin film, the impressing velocity is very sensitive to the boundary conditions. In fact it suggests a possible experimental way to detect debonding at the interface between the thin film and the substrate.

Impression creep of lead

1994 ◽  
Vol 9 (4) ◽  
pp. 903-908 ◽  
Author(s):  
Donyau Chiang ◽  
J. C. M. Li
Keyword(s):  
Creep Test ◽  
Elevated Temperatures ◽  
Constant Load ◽  
Constant Stress ◽  
Tensile Creep ◽  
Indentation Creep ◽  
Impression Creep ◽  
Creep Tests ◽  
Creep Measurements ◽  
Cylindrical Punch

The impression creep behavior of lead was investigated using a 100 μm diameter punch at ambient and elevated temperatures (433 K-563 K) under punching stresses of 6–70 MPa. The results were compared with the data obtained from conventional creep tests reported in the literature. Unlike the indentation creep test, the impression creep test showed a steady-state velocity after a short transient period when the flat-end cylindrical punch was pushed against the lead surface by a constant load. Both the temperature and stress dependences were comparable to those of the constant stress tensile creep tests under similar conditions. A master curve for lead was established by collecting data from the impression creep tests and the constant stress tensile creep tests. The indentation creep measurements for lead were included also. However, the indentation data depend on the load applied.

Clean Electron Microscope Substrate Films Used for Micrometeorite Collection and Study

1967 ◽  
Vol 25 ◽  
pp. 366-367
Author(s):  
D. M. Davies ◽  
R. Kemner ◽  
E. F. Fullam
Keyword(s):  
Thin Film ◽  
Electron Microscope ◽  
High Altitude ◽  
Amyl Acetate ◽  
Temperature Variations ◽  
Film Forming ◽  
Film Specimen ◽  
Particulate Contaminants

All serious electron microscopists at one time or another have been concerned with the cleanliness and freedom from artifacts of thin film specimen support substrates. This is particularly important where there are relatively few particles of a sample to be found for study, as in the case of micrometeorite collections. For the deposition of such celestial garbage through the use of balloons, rockets, and aircraft, the thin film substrates must have not only all the attributes necessary for use in the electron microscope, but also be able to withstand rather wide temperature variations at high altitude, vibration and shock inherent in the collection vehicle's operation and occasionally an unscheduled violent landing.Nitrocellulose has been selected as a film forming material that meets these requirements yet lends itself to a relatively simple clean-up procedure to remove particulate contaminants. A 1% nitrocellulose solution is prepared by dissolving “Parlodion” in redistilled amyl acetate from which all moisture has been removed.

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