msm^m mmmmmmamKmmmm mmmi mmmmmsmmmmmmmmmsm 





gram samples of the candidate mixtures (Table 5). Mixtures of 10% by 

 weight of copper or iron with magnesium gave the best combination of 

 rate and efficiency at reasorable cost. Although the reaction rates of 

 the magnesium-copper couple were higher, the magnesium-iron reacted at 

 a store consistent rate over an extended period. As a result, the 

 magnesium- iron couple was selected for larger scale tests. 



The previous investigations addressed the power output control 

 question by adding small amounts of seawater to. the dry powder mixtures. 

 When sufficient amounts of seawater were added to wet the entire powder 

 volume, maximum power output was achieved; however, further additions of 

 seawater had no appreciable effect. For the large-scale tests, control 

 was attempted by metering the powder mixture into a chamber filled with 

 seawater. The feasibility of controlling the reaction in this manner 

 was proved; however, difficulty was encountered in adding the dry powder 

 to the electrolyte. 



To facilitate the addition of the reactants to the electrolyte, an 

 effort was made to develop an inert slurry with the powder. A mixture 

 of 50% morpheline and 50% powder formed a fairly stable slurry for 

 pumping. However, the powder tended to settle out of the mixture, and 

 the slurry was not completely inert; therefore, some reaction occurred 

 within the slurry. A second slurry was prepared thar. resembled tooth- 

 paste in consistency. This gel was completely stable and did not react 

 with the powder. Its composition was: 



! 



Constituent Proportion (by weight) 



Magnesium-iron powder 447.0 



Carbowax ® MPEG 394.0 



Armeen®Z <19.7 



Cab-0-Sil® 3.0 



Diethylenetriamine (DETA) 1.0 



• 



The slurry was added to the reaction chamber with a caulking gun. 

 The large-scale tests showed that the slurry could be easily added to 

 the seawater, but that continued stirring was necessary to keep the 

 reaction at a constant rate. The slurrying agents were found to have no 

 detrimental effect on the reaction. A specific output of approximately 

 500 W-hr/lb of reactant (3.95 MJ/kg) was achieved with the powdered 

 metal reaction. With further development the specific output might be 

 competitive with the dual-plate-type cell. 



The most important result of the powdered metal tests is that an 

 inert slurry has been developed. In slurry form, the powdered reactants 

 can be supplied on a demand basis. By varying the slurry addition rate 

 to a reaction chamber, power can be controlled. 



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