Solubility of AlN-submicropowders of vacuum aluminothermic origin
DOI: 10.62564/M4-VS1208
Victor Garbuz, Vera Sydorenchuk, Lyudmila Kuzmenko, Tatiana Silinska, Tatiana Khomko, Valeriy Muratov, Larisa Romanova
Frantsevich Institute for Problems of Materials Science National Academy of Science of Ukraine
AlN powders in a wide range of sizes and purposes have influential applications from functional and composite ceramics to film technologies in electronics [1]. Products of topological vacuum-thermal interaction in the system: submicron B₁₂Al and AlN "BN-Al" powders are used in the production of dense resistive ceramics. Surprisingly, micron AlN powders did not want to be wetted by boiling 20% NaOH solution. Vacuum-thermal AlN dissolves exothermically. X-ray diffraction studies confirmed the hexagonal structure of the space group of wurtzite P6₃mc. The average size of AlN crystallites was determined to be ≈ 40 nm in the field of coherent reflection scattering. Solid B₁₂Al was selectively dissolved with HNO₃=1:10 solution. The black AlN precipitate (vs. white 100 nm in [1]) was filtered, washed with 5% citric acid, ethanol, dried (130⁰C), sieved and packed in a sealed container. The nuances of solubility of AlN are known in reference books. The results of comparative experiments were obvious. A reversible Gleiter effect of the spatial transition of a significant number of internal 3D atoms of Al and N to the 2D surface of crystallitesnano is observed. The mass fraction of oxygen in powders can be a measure of this process. Peripheral Al-atoms have partially broken chemical bonds. Contact with air causes recombination with oxygen in the presence of water vapor. Bridging bonds of the type (=N˃Al-O(HO)Al˂N=)n are formed by the hydrate-solvate mechanism. According to the data of pulse reduction extraction with carbonin helium flow and gas chromatography, the mass fraction of oxygen in AlN powders decreases with the growth of crystallites. Plasma chemical samples (up to 10 nm) contain 3.2% (by mass) oxygen. Al-thermal samples (40-50 nm) are oxidized by 1.9% (by mass). In furnace synthesis samples (up to 1µ), oxygen is 0.75% (by mass), respectively.
