8 Iranian Journal of Materials Science & Engineering Vol. 8, Number 3, September 2011 1. INTRODUCTION Microwaves are used for many industrial and scientific purposes. Microwave use is a novel way of processing materials due to its special characteristics as a heating source; including its environment friendliness, reduction in time and energy consumption and also its ability to produce unique microstructures[1-3]. One of the microwave applications in material processing, which has a great potential for different innovations, is material synthesis[4-6]. Synthesis of ceramics and ceramic based materials is one of the great successes achieved[7]. Taking this achievement into account; its use as a new way of in-situ combustion synthesis of Intermetallics and their composites seems to be a great ground of study[8,10]. Numerical simulation of microwave processing has been the subject of various studies[11-20]. Alpert and Jerby numerically modeled the coupled thermal-electromagnetic heating of microwave [19]. Ying and others worked on numerical modeling of organic reactions [20]. However, numerical simulation of combustion synthesis of TiAl/Al 2 O 3 composite via microwave heating from the initial powder mixture of TiO 2 /Al has not been numerically simulated till now. In this study a numerical model has been developed to simulate the combustion synthesis of TiAl/ Al 2 O 3 composite via microwave heating. To verify the model, predicted results were compared with the data published in the literature. The model was further used to study the effect of different parameters on the combustion synthesis of TiAl/Al 2 O 3 composite. 2. NUMERICAL MODEL A numerical model for microwave heating of a cylindrical compact of 3TiO 2 +7Al mixture of 8mm diameter and 4mm height was developed. It was assumed that two SiC blocks were placed on the two sides of the compact to absorb microwaves and convert their energy to heat. The combustion synthesis reaction was considered as follows: 7Al +3TiO 2 = 3TiAl + 2Al 2 O 3 (1) The microwave input power was assumed to be 800 W and the oven was a single mode one. NUMERICAL MODELING OF THE COMBUSTION SYNTHESIS OF TiAl/Al 2 O 3 COMPOSITE VIA MICROWAVE HEATING S. Ghafurian 1 , S. H. Seyedein 1 , M. R. Aboutalebi 1,* and M. Reza Afshar 2 * mrezab@iust.ac.ir Received: March 2011 Accepted: July 2011 1 Centre of Excellence for Advanced Materials and Processing (CEAMP), School of Metallurgy & Materials Eng., Iran University of Science and Technology, Tehran, Iran. 2 Department of Material Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran. Abstract: Microwave processing is one of the novel methods for combustion synthesis of intermetallic compounds and composites. This method brings about a lot of opportunities for processing of uniquely characterized materials. In this study, the combustion synthesis of TiAl/Al 2 O 3 composite via microwave heating has been investigated by the development of a heat transfer model including a microwave heating source term. The model was tested and verified by experiments available in the literature. Parametric studies were carried out by the model to evaluate the effects of such parameters as input power, sample aspect ratio, and porosity on the rate of process. The results showed that higher input powers and sample volumes, as well as the use of bigger susceptors made the reaction enhanced. It was also shown that a decrease in the porosity and aspect ratio of sample leads to the enhancement of the process. Keywords: Combustion Synthesis, Microwave Processing, Aluminum-Titanium Intermetallic Compounds, TiAl/Al 2 O 3 Composite, Numerical Modeling. [ Downloaded from ijmse.iust.ac.ir on 2021-11-26 ] 1 / 9