High temperature reactions of silicon halides with alkali metals for the production of solar grade silicon in volume at low cost were studied. Experiments were performed to evaluate product separation and collection processes, measure heat release parameters for scaling purposes, determine the effects of reactants and/or products on materials of reactor construction, and make preliminary engineering and economic analyses of a scaled-up process. Dickson, C. R. and Gould, R. K. Unspecified Center NASA-CR-162871, AEROCHEM-TN-212, DOE/JPL-955491-80/2, JPL-9950-326, QR-2 JPL-955491

This program is directed toward the development of processes involving high temperature reactions of silicon halides with alkali metals for the production of solar grade silicon in volume at low cost. Experiments are being performed to evaluate product separation and collection processes, measure heat release parameters for scaling purposes, determine the effects of reactants and/or products on materials of reactor construction, and make preliminary engineering and economic analyses of a scaled-up process. Samples of the silicon product will be delivered to JPL for evaluation of solar cell performance. During this reporting period the silicon reactor test apparatus reached operational capabilities after a shutdown for two months. Several design improvements were made while returning it to an operational stage. During the initial series of experiments complete product separation of the silicon from the salt was achieved and small samples (approx. = 3 to 40 g) of fused silicon were collected. The test apparatus is now being operated on a routine basis for periods of about twenty minutes. Finally, the initial work began on the engineering and economic analysis for scale-up of the silicon production process.

This program is directed toward the development of processes involving high temperature reactions of silicon halides with alkali metals for the production of solar grade silicon in volume at low cost. Experiments are performed to evaluate product separation and collection processes, measure heat release parameters for scaling purposes, determine the effects of reactants and/or products on materials of reactor construction, and make preliminary engineering and economic analyses of a scaled-up process. During this report period work concentrated on preparing samples of silicon for purity analyses. The results of six such analyses are given. In general, they indicate that the process is capable of producing very pure silicon. A number of impurity elements appear in 0.1 to 10 ppMa concentrations in one or another of the samples in unpredictable patterns. This would be expected for the one hour runs performed since atmospheric dust has easy access to collection surfaces during assembly and laboratory conditions do not allow clean assembly procedures to be followed. Particularly encouraging is the observation that sodium levels are below 10 ppMa in most runs.

This program is directed toward the development of processes involving high temperature reactions of silicon halides with alkali metals for the production of solar grade silicon in volume at low cost. Experiments are being performed to evaluate product separation and collection processes, measure heat release parameters for scaling purposes, determine the effects of reactants and/or products on materials of reactor construction, and make preliminary engineering and economic analyses of a scaled-up process. Samples of the silicon product will be delivered to JPL for evaluation of solar cell performance. During this reporting period, the program efforts were directed toward the measurement of reagent flow rates and silicon collection efficiencies, the construction of a new sodium heat pipe to permit one to two hour runs, and the completion of the economic and engineering analyses of the AeroChem process to make solar grade silicon. Progress is reported.