Ramana Reddy

Abstract:

The discontinuously reinforced metal matrix composites (MMCs) offer several advantages over conventional alloys. For nanosize materials synthesis, high nucleation and low growth rates are required. Thermal plasma could provide these requirements for synthesis of nanocomposite materials. This presentation will review the various types of in-situ processing of nanocomposites. The thermal plasma processing of nanoscale lightweight alloy matrix TiC and TIN composites is discussed. The in-situ formed reinforcements are thermodynamically stable and disperse uniformly in the alloy matrix. The alloy -TiN composite was synthesized in a non-transferred arc D.C. plasma reactor from ilmenite ore concentrate using methane and nitrogen as the reactive gases. The standard Gibbs energy minimization method was used to calculate the equilibrium composition of reaction species. A mathematical model was developed to describe the plasma gas and particle dynamics and conversion yields. The model was used to study the thermal decomposition of ilmenite in the non-transferred arc plasma reactor. The computed production rates of TiN from ilmenite using nitrogen and methane gas mixtures are in the range of 0.6 to 3.37 kg/m3/s at 2500 K. The products were characterized with SEM, EDAX, and X-ray diffraction. Experimental results showed that composite with matrix alloy and reinforced nanoscale TiN was formed. The discontinuous reinforcement TiN was well distributed in the matrix phase of alloy. TiN dimension are about 300 nm. The production of composites powders and advanced materials by plasma technology are discussed.