Techniques combustion synthesis

In the past few years there still have been some research efforts focused on Mg NiH. The Akiyama s group in Japan [20-22] has developed a hydriding combustion synthesis technique for the direct fabrication of Mg NiH. The results showed that the product of Mg NiH from the hydriding combustion synthesis absorbed the maximum (3.4-3.6 wt%) near the theoretical value just after synthesis without any activation process. 

The combustion synthesis technique consists of bringing a saturated aqueous solution of the desired metal salts and a suitable organic fuel to the boil, until the mixture ignites a self-sustaining and rather fast combustion reaction, resulting in a dry, usually crystalline, fine oxide powder. By simple calcination, the metal nitrates can, of course, be decomposed into melt oxides upon heating to or above the phase transformation temperature. 

This review article summarizes the state of the art in combustion synthesis, from both the scientific and technological points of view. In this context, we discuss wide-ranging topics including theory, phenomenology, and mechanisms of product structure formation, as well as types and properties of product synthesized, and methods for large-scale materials production by combustion synthesis technique. 

In this section, we discuss the laboratory techniques and production technologies used for the combustion synthesis process. The laboratory studies reveal details of the CS process itself, while the technologies may also include other processing, such as densification of the product by external forces. In both cases, it is necessary to control the green mixture characteristics as well as the reaction conditions. For the production technologies, however, optimization of parameters related to external postcombustion treatment is also necessary in order to produce materials with desired properties. 

Currently, other U.S. companies have also acknowledged the economic benefits of combustion-synthesized materials and are involved in pilot-scale production. However, for proprietary reasons, the details are not available. It is likely that in the future, as materials produced by combustion synthesis demonstrate unique properties (e.g., nanophase and disordered materials) compared with conventional methods and its economical benefits become more evident, the technique will receive more attention. 

The thermite process may be the original inspiration of combustion synthesis (CS), a relatively new technique for synthesizing advanced materials fl-om powder into shaped products of ceramics, metallics, and composites. Professor Varma and his associates at Notre Dame contributed the article Combustion Synthesis of Advanced Materials Principles and Applications, which features this process that is characterized by high temperature, fast heating rates, and short reaction times. 

Combustion synthesis of diamond films fi om atmospheric pressure oxyacetylene flame was first reported by Hirose in 1988.This technique, as shown schematically in Fig. 2h, has been demonstrated to be a potentially very important means of growing diamond (Table 1). In Hirose s experiments, linear growth rates of100-200 pmh were achieved. The results were then confirmed by Hanssen et al.l l In Hirose s experiments and most of those that followed, the oxyacetylene torch was typically run with... 

Chou, Y.-S., Stevenson, J. W., TArmstrong, T. R. LPederson, L. R. Mechanical Properties of Lal-xSrxCo0.2Fe0.803-8 Mixed-Conducting Perovskites Made by the Combustion Synthesis Technique. Journal of American Ceramic Society 83, 1457-1464 (2000). 

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