Papers by Keyword: Gas-Liquid Reaction

Abstract: Aluminum nitride (AlN) possesses superior thermal and electrical properties and is an ideal candidate for high-temperature, as well as for packaging and optoelectronic applications. Aluminum based composites reinforced with AlN have been manufactured via an in situ gas-assisted process, where a nitrogen-bearing gas is injected in the molten aluminum at 1273-1323 K. The process is carried out in an inert atmosphere in order to avoid oxygen contamination. Addition of Mg lowered the oxygen content in the melt by forming MgO and thus favoring the nitridation reaction. Particle size formed in the matrix varied from 1- 3 μm to sub-micron scale depending on the gas injection time. Longer bubbling times give rise to improved reinforcement dispersion. Addition of Si is detrimental for the synthesis of AlN; Mg₂Si phase precipitates, replacing the formation of MgO and hindering the nitridation reaction. The challenges of controlling the kinetics are discussed.

Abstract: In the last two decades, metal matrix nanocomposites have witnessed tremendous growth. Particulate-reinforced nanocomposites have been extensively employed in the automotive industry for their capability to withstand high temperature and pressure conditions. Several manufacturing approaches have been used to fabricate them. Non-homogeneous particle dispersion and poor interface bonding are the main drawbacks of conventional manufacturing techniques. A critical review of nanocomposite manufacturing processes is presented; the distinction between ex-situ and in-situ processes is discussed in some detail. Moreover, in-situ gas/liquid processes are elaborated and their advantages are discussed. The thermodynamics and kinetics of the reaction between the precursor gas and the liquid metal have been analyzed and their role on particle formation studied. This critical review will provide the reader with an overview of nanocomposite manufacturing methods along with a clear understanding of advantages and disadvantages.