The objective of this study was to develop an efficient "real time" measurement system able to directly measure, with microgram resolution, the dissolution rate of absorbable glass fibers, and utilize the system to evaluate the effectiveness of silane-based sizing as a means to delay the fiber dissolution process. The absorbable glass fiber used was calcium phosphate (CaP), with tetramethoxysilane selected as the sizing agent. E-glass fiber was used as a relatively nondegrading control. Both the unsized-CaP and sized-CaP degraded linearly at both the 37 degrees C and 60 degrees C test temperature levels used. No significant decrease in weight-loss rate was recorded when the CaP fiber tows were pretreated, using conventional application methods, with the tetramethoxysilane sizing for either temperature condition. The unsized-CaP and sized-CaP weight loss rates were each significantly higher at 60 than at 37 degrees C (both p < 0.02), as expected from dissolution kinetics. In terms of actual weight loss rate measured using our system for phosphate glass fiber, the unsized-CaP fiber we studied dissolved at a rate of 10.90 x 10(-09) and 41.20 x 10(-09) g/min-cm(2) at 37 degrees C and 60 degrees C, respectively. Considering performance validation of the developed system, the slope of the weight loss vs. time plot for the tested E-glass fiber was not significantly different compared to a slope equal to zero for both test temperatures.

The low-temperature viscosities of two series of sodium aluminosilicate glasses were measured by the fiber elongation method. The results suggested that a modification of the Day and Rindone structural mode1 for sodium ahminosilicate glasses was necessary. The modified model suggests that additional (AIOa,z)-groups form at AI/Na ratios >l.

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Various Na2SO4‐Na2CO3‐CaCO3‐SiO2 combinations were studied by differential thermal analysis to elucidute the role of Na2SO4 in soda‐lime‐silica glassmelting reactions. It was found that Na2SO4 encourages the formation of wollastonite at 850° to 900°C. The solid‐state reaction of Na2Ca(CO3)2 occurs very readily at temperatures in the vicinity of 400°C. The Na2Ca(CO3)2 must therefore be considered a major constituent in glass batches containing both soda ash and limestone.

An investment casting process has been developed to produce net-shape, superconducting ceramics. In this work, a factorial experiment was performed to determine the critical process parameters for producing cast YBa2Cu3 @ ceramics with optimum properties. An analysis of variance procedure indicated that the key variables in casting superconductive ceramics are the particle size distribution and sintering temperature. Additionally, the interactions between the sintering temperature and the other process parameters (e.g., particle size distribution and the use of silver dopants) were also found to influence the density, porosity, and critical current density of the fired ceramics.