Titanium particle combustion

R.D. Gould, Combustion Instability of Solid Propellants Effect of Oxidizer Particle Size, Oxidizer/Fuel Ratio and Addition of Titanium Dioxide to Plastic Pro pell ants , Rept No RPE-TR-68/1, Westcott (Engl)... 

Heat of combustion, thermal conductivity, surface area and other factors influencing pyrophoricity of aluminium, cobalt, iron, magnesium and nickel powders are discussed [4], The relationship between heat of formation of the metal oxide and particle size of metals in pyrophoric powders is discussed for several metals and alloys including copper [5], Further work on the relationship of surface area and ignition temperature for copper, manganese and silicon [6], and for iron and titanium [7] was reported. The latter also includes a simple calorimetric test to determine ignition temperature. 

In summary, the titanium fountain effect arises because of the combustion of the metal particles, and appears in the form of radiation which comprises ... 

Figure 12.5 Titanium-nitrogen system Effect of nitrogen pressure and solid phase dilution on combustion temperature. Particle size 29 (rm.

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... 

In an early work by Kottke and Niiler (1988), a cellular model was used to simulate the combustion wave initiation and propagation for the TH-C model system. The interactions between neighboring cells were described by the electrical circuit analogy to heat conduction. At the reaction initiation temperature (i.e., melting point of titanium), the cell is instantly converted to the product, TiC, at the adiabatic combustion temperature. The cell size was chosen to be twice as large as the Ti particles (44 /xm). Experimentally determined values for the green mixture thermal conductivity as a function of density were used in the simulations. As a result, the effects of thermal conductivity of the reactant mixture on combustion wave velocity were determined (see Fig. 21). Advani et al. (1991) used the same model, and also computed the effects of adding TiC as a diluent on the combustion velocity. 

The microstructure of the initial titanium-graphite mixture is shown in Figure 62a. When the temperature in the combustion wave reaches 1660°C, titanium melts. It was determined from quenching results that a thin film ( 0.1 / m) of the Ti melt spreads over the solid carbon surface with simultaneous formation of titanium carbide grains (Fig. 62b). Small rounded TiC particles were observed to appear within the liquid rather than in the form of a continuous product layer (Rogachev et al, 1987). To illustrate this fact further, the typical microstructure formed during combustion reaction of titanium melts with graphite whiskers (10 /.im in diameter) is shown in Fig. 62c. 

Several characteristic ratios of heterogeneity as functions of titanium particle size and sample porosity are shown in Figs. 75a and b, respectively. For the quasi-homogeneous approximation to be valid, the heterogeneity of the reactant medium should be small in comparison to the thermal length scale. As a result, the heterogeneity of the combustion front (shape and propagation) should also be small relative to the macroscopic behavior ... 

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