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This report covers the work performed on the August 1970 extension of the Advanced Research Projects Agency (ARPA) order 980. This effort was directed to ward the development of light armor materials. The 'nltial concepts behind the development of these materials 1-5 are described in previous LLL reports. Contents Foreword jfi Abstract Introduction 2 The Effect of Composition and Microstructure on Ballistic Performance of Be 2 B and Be 4 B 4

A WCI6 compound, isostructural with UCI6, has been identified by comparing calculated intensities with Debye-Scherrer patterns.During the examination of a commercial~ preparation of supposed WCIs, the material was submitted for X-ray analysis to verify the compound designation. Chemical analyses were inconclusive in determining the W:CI ratio because of difficulties with the reactivity of the compound. With the Debye-Scherrer techniques used, the pattern proved unidentifiable with any other tungsten-chlorine compound previously described (Reick, 1967). Other physical property measurements such as color and boiling point implied that the compound should be WCI6. The Debye-Scherrer pattern, however, did not conform to that of WCI6 described by Ketelaar & Oosterhout (1943).Needle-shaped single crystals of the unknown were examined on a Buerger precession camera. The diffraction symbol proved to be 3m P---with cell constants a0= 10.511+0.003, c0=5. for WC]6. Observed intensities are estimated visually from the DebyeScherrer pattern. The calculated intensities include an absorption correction for ~t=498 cm-1 and a 0-3-mm-dia. spindle. In space group P3ml, hk.l and kh.l are nonequivalent; however, no distinction between these reflections has been made in the assignment of indices.

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Processing-induced residual stresses in the component layers of Solid Oxide Fuel Cells (SOFC's) can lead to fracture or to cell curvature which impedes stack assembly. Reducing or eliminating residual stresses to improve the mechanical behavior of the cells becomes increasingly important as the area of the cells is increased to increase the power of the fuel cell stack. Residual stresses in SOFC's result primarily from differential thermal expansion and sintering shrinkage between the component layers, such as the electrolyte and the anode support in a planar cell. This work investigates the impact of anode composition on each of these factors, with the ultimate goal of designing a flat, large-area cell. A range of anode compositions is investigated to determine the effect of different additives on the sintering behavior, and on the thermal and mechanical properties. Dilatometry, sintering shrinkage, scanning electron microscopy, and reduction studies are performed to correlate the microstructure, thermomechanical behavior, and composition. The experimental results are used to select an anode composition that leads to low overall cell curvature and improved mechanical behavior with respect to standard SOFC anode cermet materials.

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