Metallic nitrides, combustion synthesis

In the field of high-temperature combustion synthesis, metals have been reacted with nitrogen, both in the gaseous and liquid phases, to form refractory nitrides [2], In most cases, this nitriding process is heterogeneous. 

Recently, studies from outside the Soviet Union have started to appear in the literature. In the US, Holt and Kingman17 reported the synthesis of transition metal nitrides not from gas-solid combustion reactions, but by using sodium azide as a solid source of nitrogen, according to the scheme ... 

Combustion synthesis of transition metal nitrides an overview 233... 

Combustion synthesis of metal nitrides from a solid nitrogen source was first investigated by Petrov in 1975.32 He used barium azide (Ba2N6) powder for the synthesis of TiN and Mg3N2. Holt, in 1983,33 reported the synthesis of TiN by using sodium azide (NaN3)as the solid nitrogen source. 

A theoretical analysis of combustion synthesis of refractory nitrides was presented by Munir and Holt in 1987.37 They predicted the existence of an activation energy due to chemical reaction or mass-transport. Glassman et al. in 1987,38 in their thermodynamic analysis of TiN formation, examined the possibility of creating TiN by a self-sustained reaction of the metal particles and nitrogen gas in a rocket motor. They reported that for the stoichiometric ratio of 0.5 mole N2/mole titanium, the reaction has... 

Hlavacek and co-workers [32] have simulated the synthesis of refractory metal nitrides by adiabatic combustion. The reactions involved occur at 2500... 

It is not essential that, for combustion synthesis, the reactants are elements and initially solid (at least one of them). Refractory carbides and nitrides with complex chemical compositions (metal halogenides, organometallics, etc.) are also formed in combustion of gaseous systems. The special features of combustion synthesis in the gas phase were analyzed in the recent review by Brezinsky (5). The synthesis in a gaseous system proceeds at a stationary combustion front with moving flows of reactants and product. Consequently, these processes differ in essence from combustion of condensed systems by the conditions of nucleation and growth of the new phase, which manifest themselves in the product morphologies. 

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