Evaluation of plasma-sprayed CoS2 cathodes for thermal batteries
Conventional electroactive stack components in thermal batteries are constructed from pressed-powder parts. These include the anode, separator, and cathode pellets (discs). Pressing parts that are less than 0.010" thick is difficult. The use of plasma spray to deposit thin CoS/sub 2/ cathode films onto a stainless steel substrate was examined as an alternative to pressed-powder cathodes. The plasma-sprayed electrodes were tested in single cells under isothermal conditions and constant-current discharge over a temperature range of 400/spl deg/C to 550/spl deg/C using standard LiSi anodes and separators based on the LiCl-KCl eutectic. Similar tests were conducted with cells built with conventional pressed-powder cathodes, which were tested under the same conditions for comparative purposes. This paper presents the results of those tests.
Thermal-sprayed, thin-film pyrite cathodes for thermal batteries-discharge-rate and temperature studies in single cells
Using an optimized thermal-spray process, coherent, dense deposits of pyrite (FeS/sub 2/) with good adhesion were formed on 304 stainless steel substrates (current collectors). After leaching with CS/sub 2/ to remove residual free sulfur, these served as cathodes in Li(Si)/FeS/sub 2/ thermal cells. The cells were tested over a temperature range of 450/spl deg/C to 550/spl deg/C under baseline loads of 125 and 250 mA/cm/sup 2/, to simulate conditions found in a thermal battery. Cells built with such cathodes outperformed standard cells made with pressed-powder parts. They showed lower interfacial resistance and polarization throughout discharge, with higher capacities per mass of pyrite. Post-treatment of the cathodes with Li/sub 2/O coatings at levels of >7% by weight of the pyrite was found to eliminate the voltage transient normally observed for these materials. Results equivalent to those of standard lithiated catholytes were obtained in this manner. The use of plasma-sprayed cathodes allows the use of much thinner cells for thermal batteries since only enough material needs to be deposited as the capacity requirements of a given application demand.
Dimensional Errors of Fixtures, Locating and Measurement Datum Features in the Stream of Variation Modeling in Machining
Machining processes are usually multi-station processes involving a large number of operations and several locating datum changes. Machining errors are thus introduced, transformed and accumulated as the workpiece is being machined. This paper introduces procedures for expressing the influence of errors in fixtures, locating datum features and measurement datum features on dimensional errors in machining. These procedures are essential in the derivation of the Stream of Variation model of dimensional machining errors using the CAD/CAPP parameters of the machining process. The linear state space form of the Stream of Variation model allows for advanced control theory achievements to be employed in formal solutions to problems in multi-station machining. Modeling procedures presented in this paper were experimentally verified in machining of an automotive cylinder head.