Nitrides infiltration combustion

Nitride composition and structure are greatly dependent on the combustion mode or the existence of a phenomenon accompanying infiltration combustion. That is, why it is necessary to work out specific approaches for developing optimum terms of final item production in each system. Nowadays, a lot of experimental studies and theoretical works allow the scientists to foresee the... 

Dependence ofSHS Nitride Composition and Structure on Infiltration Combustion Mode 21... 

Figure 1.18 Silicon infiltration combustion nitriding completeness degree ( f) on dilution...

The SHS Filtration Combustion (FC) reactor was manufactured for obtaining nitrides under the mode of infiltration combustion. It is distinguished by the oriented gas flow [30], that is, forced infiltration of reactive or impurity gases. Such reactors are equipped with pressure gages and thermal couples, and have pressure-release valves. A grade-up example of the SHS FC reactor is an SHS... 

The dependence of combustion temperature and velocity for the Si-N2 system as a function of dilution with /3-Si3N4 powder is shown in Fig. 38. In this case, at constant gas pressure, remains constant and is equal to the dissociation temperature of silicon nitride, for dilutions up to 60 wt %. However, with increasing dilution, the combustion front velocity increases. Also, increasing the overall heat evolution, smaller dilution by nonmelted nitride powder promotes coalescence of liquid Si particles, leading to an increase in the average reactant particle size, as well as to formation of thin liquid Si films, which blocks nitrogen infiltration to the reaction zone (Mukasyan et al, 1986). The same effects were also observed for the AI-N2 and B-N2 systems (Mukasyan, 1994), which are characterized by dissociation of the final product in the combustion wave. 

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