Method of optimizing composite preparation for electrical properties: maximum capacitance electrodes
AssigneeAuburn University
InventorBruce J. Tatarchuk
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Abstract
Composites of a matrix of metal fibers and carbon fibers interlocked in and interwoven among a network of fused metal fibers are inherently capable of displaying a broad range of values of a particular physical property. Where the composite is made by sintering a preform of the fiber network dispersed in a matrix of an organic binder, the value of the physical property of the resulting composite is a function of several independent variabiles which can be controlled during composite fabrication. With particular regard to the capacitance of a stainless steel-carbon fiber electrode, there is described a method of optimizing capacitance during electrode fabrication.
Claims28
A method of optimizing the capacitance of a stainless steel fiber-carbon fiber composite electrode made by sintering in a hydrogen atmosphere a preform of a network of stainless steel and carbon fibers dispersed in a matrix of an organic binder, where the capacitance is optimized with respect to the independent variables of sintering temperature between a minimum temperature of T.sub.min and a maximum temperature of T.sub.max, sintering time, and the weight ratio of stainless steel fibers to carbon fibers at a constant carbon content between a minimum ratio of ratio.sub.min and a maximum ratio of ratio.sub.max, said method of optimizing comprising determining within the envelope bounded by T.sub.min, T.sub.max, ratio.sub.min and ratio.sub.max :
- the rate equation, including apparent activation energy, for the increase in capacitance of the composite electrode;
- the rate equation, including apparent activation energy, for the decrease in capacitance of the composite electrode;
- from the two prior rate equations, the optimal sintering time at which the capacitance is maximized at a given sintering temperature and a given stainless steel to carbon ratio within said envelope;
- the capacitance at the optimal sintering time as a function of the sintering temperature and stainless steel to carbon ratio;
- choosing the temperature, T.sub.opt, at which the capacitance is maximized with respect to a stainless steel to carbon ratio within said envelope, and choosing that stainless steel to carbon ratio at T.sub.opt where the capacitance is a maximum.
A method of optimizing a physical property of a metal fiber-carbon fiber composite which is a network of said fibers having a plurality of bonded junctions at the metal fiber crossing points and made by sintering in a hydrogen atmosphere a preform of a network of metal and carbon fibers dispersed in a matrix of an organic binder, where the physical property is optimized with respect to the independent variables of sintering temperature between a minimum temperature of T.sub.min and a maximum temperature of T.sub.max, sintering time, and the weight ratio of metal fibers to carbon fibers at a constant carbon content between a minimum ratio of ratio.sub.min and a maximum ratio of ratio.sub.max, said method of optimizing comprising determining within the envelope bounded by T.sub.min, T.sub.max, ratio.sub.min and ratio.sub.max :
- the rate equation, including apparent activation energy, for the increase in the value of said physical property of the composite;
- the rate equation, including apparent activation energy, for the decrease in the value of said physical property of the composite;
- from the two prior rate equations, the optional sintering time at which the value of said physical property is maximized at a given sintering temperature and a given metal to carbon ratio within said envelope;
- the value of said physical property at the optimal sintering time as a function of the sintering temperature and metal to carbon ratio;
- choosing the temperature, T.sub.opt, at which the value of said physical property is maximized with respect to a metal to carbon ratio within said envelope, and choosing that metal to carbon ratio at T.sub.opt where the value of said physical property is a maximum.
Dependencies are inferred from the claim text.