Abstract: The present invention is a method of rapidly and reproducibly checking the quality of zirconium base material welds and heat affected zones. In this method, weldment samples are immersed in an elevated temperature fused salt bath for a time period sufficient, at the bath temperature selected, to produce an essentially black oxide film in acceptable quality welds while producing a scaling oxide in unacceptable welds.

Abstract: Disclosed is a nasicon compound and a method of making it. The nasicon compound is rhombohedral at room temperature and has the general formulaM.sub.1+x+O.02y+0.04z M'.sub.2-0.02(y+z) M".sub.0.02y M"'.sub.0.02z M"".sub.x M""'.sub.3-x O.sub.12where M is selected from lithium, sodium, calcium, and silver, M' is selected from zirconium, titanium or hafnium, M" is selected from yttrium, scandium or lanthanum, M"' is selected from magnesium, calcium, strontium or barium, M"" is selected from silicon and germanium, M""' is selected from phosphorous and arsenic, x is about 1.6 to about 2.2, y is about 0 to about 15, and z is about 0 to about 15. The preferred compound isNa.sub.1+x Zr.sub.2 Si.sub.x P.sub.3-x O.sub.12.A sodium sulfur battery using the nasicon compound is also disclosed.