(中南工業(yè)大學材料系，長沙410083)
摘 要: 通過熱力學分析研究了超硬無機材料，如Sic、Si3N4、TiC、TiN等納米粉末的化學氣相沉積(CVD)合成反應過程和核化過程的有關(guān)熱力學規(guī)律。結(jié)果表明：合成物以共價鍵和以金屬鍵為主的合成反應和化學反應過程對溫度、壓力均比較敏感，熱力學驅(qū)動力隨溫度變化增加比較明顯，對外壓的敏感表現(xiàn)為增大壓力對合成反應不利。合成物以離子鍵為主時，反應的熱力學驅(qū)動力隨溫度變化不明顯，外壓的影響也不顯著。對于核化過程，合成物以金屬鍵和離子鍵為主的體系，核化所需臨界過飽和度較低，lg(p／po)在1~10之間，而對合成物以共價鍵為主的體系，核化所需過飽和度較高，lg(p／po)約在15~20之間，因?qū)嶒炦^程很難達到這樣高的過飽和度，因此合成粉體常以非晶態(tài)形式存在，以降低核化阻力。
關(guān)鍵字: 超硬無機材料 納米粉末 化學氣相沉積(CVD) 熱力學
INORGANIC MATERIAL NANOSIZED POWDER CVD
SYNTHESIS PROCESSES
（1.Department of Materials Science and Engineering,
Central South University of Technology, Changsha, 410083
2．Research Laboratoryfor Inorganic Chemistry,Hungarian Academy of Sciences,H-1112, Budapest）
Abstract:Thermodynamic analyses for the superhard inorganic material, such as SiC, Si3N4,TiC,TiN and so on, nanosized powder CVD synthesis processes were made systematically. For the metallic and the covalent bonding compounds, the synthesis reaction thermodynamic driving forces increased with the synthesis temperature considerably, compared with the ionic bonding compound synthesis reaction. The system pressure increase was of noticeable negative influence on the metallic and covalent bonding compound synthesis, but for the ionic compounds, its effect could be neglected. During the nucleation processes, the critical supersaturation for the metallic and the ionic bonding compound synthesis reaction was about 1~10, much lower than that for the covalent bonding compound synthesis, which was in the range of 15~20. In practice, it was impossible for the covalent bonding compound synthesis reaction to meet the above requirement.Therefore, in most cases the as-synthesized powder exists in amorphous state to reduce the nucleation activation energy.
Key words: inorganic compounds nanosized powder CVD synthesis thermodynamic analyses
