溶胶凝胶自燃烧法合成金属与合金材料研究进展

本文综述了溶胶凝胶自燃烧法制备金属与合金材料的研究进展, 详细介绍了该方法的实验原理和技术路线, 通过实例介绍了该方法在制备金属和合金材料中的具体应用. 通过这一系列的工作介绍, 我们证实可以把传统的溶胶凝胶法制备氧化物材料的技术拓展到金属与合金材料的制备, 希望能够对材料研究的实验工作有所帮助.

Progress in sol-gel autocombustion synthesis of metals and alloys

This paper is an overview of the progress of sol-gel autocombustion synthesis of metals and metal alloys. Sol-gel is a convenient method to synthesize a variety of oxides by mixing of different elements at an atomic level. Autocombustion synthesis is a self-sustaining process caused by the heat generated from its exothermic reaction. By combining these two methods, the sol-gel autocombustion method is introduced in the synthesis of metals and metal alloys. The experimental principle and technological route are introduced in detail in this review. By using metal nitrate, citric acid etc. as starting materials, the dried gels are prepared through sol-gel routine. Under the protection of inert gas, the autocombustion could be activated at low temperature in a tube furnace. After the autocombustion was activated, the gel burned violently, and a large amount of white gas was refleased. During heating the gel, mass spectrum shows that the H₂, CO and CH₄ areflevidently identified near the combustion temperature. They are well known reducing agents, which can be used in the redox reaction for synthesizing metals from oxides. Based on the data obtained from the TG-DTA and mass spectrum analysis, it is speculated that there are mainly five reactions appearing during the burning of the gel at high temperature: exothermic reaction between fuel and oxidant; metal oxide(s) formation by decomposition of the nitrate(s); generation of CH₄, CO and H₂ by the decomposition of CH_x containing groups of complexing agent; exothermic reaction between CH₄/CO/H₂ and oxidant; the reduction of metals from their corresponding metal oxides by CH₄ and H₂ in nascent product. The application of this method to the synthesis of metals and metal alloys is shown by realized examples. This method shows many advantages in the synthesis of metals, such as simple apparatus, inexpensive raw materials, a relatively simple preparation process, and fine powder products with high homogeneity. Moreover, very low temperature is required to activate the reaction, and then the combustion can continue to take place without needing additional energy supply. This method has potential applications in experimental material reflearches.