The production of aluminum nitride (AlN) from aluminum metal was investigated in this study. The nitridation of Al (in rod, powder, and thin-plate forms) was facilitated by dissolving the Al 2 O 3 thin films formed on the Al samples with a molten fluoride mixture (KF-45 mol% AlF 3 , KF, or LiF-50 mol% KF). AlN was formed when NH 3 gas was supplied to the Al sample (in both solid and liquid forms) wetted by molten fluoride mixture. The lowest temperature at which AlN was successfully produced was 773 K. No AlN was formed when N 2 or H 2 -25% N 2 gas was supplied to the Al sample, even when a molten fluoride mixture was used. The reaction rate for the nitridation of Al powder increased with the temperature and reached 99% after 3 h at 1173 K. AlN thin films of 2-5 lm thickness were formed on Al thin plates (0.075-1.0 mm thick) at 873 K.

The decomposition of polychlorobiphenyls (PCBs) by means of basic molten salts was investigated in order to construct a safe, simple and highly efficient waste treatment system for PCBs. PCBs (mono, di, tri, tetra, penta, hexa, hepta-chlorobiphenyls) solution was injected into basic molten salts (KOH-K2CO3 or NaOH-Na2CO3) at 773-973 K with oxygen or imitation air. The mass of residual PCBs in the exhaust after the decomposition and the mass of PCBs condensed inside the reaction vessel were measured by using gas chromatograph mass spectrometry, and the decomposition efficiency of PCBs was determined. The decomposition efficiency was also determined from the residual concentration of PCBs in the exhaust in some experiments. The decomposition efficiency was high regardless of the number of chlorine contained in PCBs and reached to very high of 99.999% in an optimum condition. Chlorine of PCBs was captured in basic molten salts, and organic compounds containing chlorine was not emitted from the molten salts. Some by-products comprising benzene rings were found at 773-873 K, but the by-products disappeared at 973 K.

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