Showing papers on "Surface-area-to-volume ratio published in 1993"
376 citations
TL;DR: In this paper, a piston-cylinder gas spring is used to provide a force varying with distance, similar to that provided by a mechanical spring, and a theoretical model was found to predict results well, over most of the operating range.
Abstract: Gas springs are devices in which the compressibility of a gas is used to provide a force varying with distance The force-distance relationship is similar to that provided by a mechanical spring Experiments were performed on a piston-cylinder gas spring Speed, cyclic mean pressure, gas, bore/stroke ratio, volume ratio, and internal extended surface geometry were varied Hysteresis loss, pressure wave magnitude, and pressure-volume phase shift were measured Nondimensional variables were found to correlate results, and a theoretical model was found to predict results well, over most of the operating range
48 citations
TL;DR: In this article, an X-ray technique for the measurement of internal residual strain gradients near the continuous reinforcements of metal matrix composites has been investigated, which utilizes high intensity white Xray radiation from a synchrotron radiation source to obtain energy spectra from small volumes deep within composite samples.
Abstract: An X-ray technique for the measurement of internal residual strain gradients near the continuous reinforcements of metal matrix composites has been investigated. The technique utilizes high intensity white X-ray radiation from a synchrotron radiation source to obtain energy spectra from small (10-3 mm3) volumes deep within composite samples. The energy peak positions satisfy Bragg’s law and allow determination of the lattice parameter. As the probe volume is translated, the peaks of the spectra shift and are used to infer lattice spacing changes and thus strains with a precision of 10-3 to 10-4 (depending on the sample grain size/probe volume ratio). The viability of the technique has first been tested using a model system with 800 μm A12O3 fibers and a commercial purity titanium matrix. For this system (which remained elastic on cooling), good agreement was observed between the measured residual radial and hoop strain gradients and those estimated from a simple elastic concentric cylinders model. The technique was then used to assess the strains near (SCS-6) silicon carbide fibers in a Ti-14Al-21Nb matrix after consolidation processing. Reasonable agreement between measured and calculated strains was seen provided the probe volume was located 50 μm or more from the fiber/matrix interface. Close to the interface, the measured elastic strains were smaller than anticipated, due to relaxation of the residual stress by plasticity and radial cracking during sample cooling.
28 citations
TL;DR: In this article, an overview of the evolution of surface layers and factors affecting the alteration rate when glass is subjected to an aqueous environment is presented. But the authors focus on the evolution and evolution of the surface layers, and not on the role of various layers in the alteration process.
Abstract: This paper provides an overview of waste glass alteration. Emphasis is on the evolution of surface layers and factors affecting the alteration rate when glass is subjected to an aqueous environment. The extent, type and rate of alteration is determined by a variety of parameters including time, temperature, glass composition, pH, Eh, composition of leachate/geology, the presence of other engineered barriers, flow conditions and surface area/volume ratio. Models (based on kinetic and thermodynamic considerations) developed by other researchers that are consistent with the experimental observations from the laboratory and field experiments are discussed. The morphology of the surface layers as described by interpretation of secondary ion mass spectrometry (SIMS) analyses on waste glasses and the role the various layers play in the alteration process is presented as well.
15 citations
Patent•
16 Nov 1993
TL;DR: In this article, the average Debye characteristic temperature and average atomic weight are calculated based on the composition, lattice spacing, and atomic Debye temperature, and at the same time the temperature factors are calculated by using the lattice spacings.
Abstract: PURPOSE:To measure residual austenite by calculating temperature factors using respective average Debye characteristic temperatures, atomic weights, lattice spacings on the basis of the chemical composition of crystal phase in an alloy steel and obtaining crystal structural factors based on the average atomic scattering factors and lattice spacing. CONSTITUTION:The chemical composition of austenitic and ferritic phases in a sample steel is analyzed and average Debye characteristic temperature and average atomic weight are calculated based on the composition, lattice spacing and atomic Debye characteristic temperature. The average temperature and average atomic weight are substituted for the Debye characteristic temperature and atomic weight, and at the same time the temperature factors are calculated by using the lattice spacing. In addition, average atomic scattering factor is calculated based on the chemical composition and lattice spacing and the crystal structural factor is then calculated by using the average factor. Furthermore, using a constant that is dependent on the kind of substance based on Lorentz polarization factor, lattice spacing, multiplinty and temperature factor, the residual austenitic volume ratio can be measured by diffraction X-ray peak intensity ratio and theoretical diffraction X-ray intensity ratio of austenitic phase and ferritic phase.
4 citations