โ Scribed by Pink, Francis X. ;Ostreicher, Kim J.
No coin nor oath required. For personal study only.
Transmission electron microscopy has been used to isolate and examine the intergranular glass phase in hot-pressed silicon nitride/silicon carbide composites. Previously there have been difficulties in locating a suitable region for studies of this nature because the interfering nitride and carbide grains inhibit isolation of the glass for examination. Radiofrequency plasma etching of thinned sections of 6 wt% Y2O3, 2 wt% A12O3 in Si3N4 containing 30 vol% of SiC proved to be fruitful in isolating the glass phase. A mixture of CF4 and O2 quantitatively remove the acicular nitride phase without any evidence of attack on either the glass or carbide. Composites containing ceria and magnesia as substitutes for yttria behave similarly. This indicates that glasses containing minor to major concentrations of elements forming stable fluorides inhibit the attack of fluoride ions on silica glasses containing these elements.
๐ SIMILAR VOLUMES
Ribbon against drop (R.A.D.) ribbons exhibit a polycrystalline texture similar to that of most melt-grown ribbons; we review here the defects of as-grown materials as well as after the solar cells' production.