Mohamed Radwan

Enhanced thermal conductivity of polymer composites filled with three-dimensional brushlike AlN nanowhiskers

The thermal conductivity of polymer composites was improved by loading three-dimensional (3D) brushlike AlN nanowhiskers fillers synthesized by simple combustion method. Through filling 47 vol % of the synthesized AlN nanowhiskers, the thermal conductivity of the composite was significantly increased to 4.2 W m−1 K−1, which was 2.3 times higher than that of the composite filled with the same content of commercial AlN equiaxed particles. According to Agari model analysis and microstructure observation, the thermal conductivity enhancement can be ascribed to the 3D brushlike AlN nanowhiskers promoted the formation of a more effect percolating network in the matrix with lower thermal resistance.

Synthesis of Monolithic β-Sialon Powders (Si6−zAlzOzN8−z, Z = 2−4) through Controlling the Combustion Reaction Temperature

Pure ?-sialon powders with the controlled z values (z = 2? 4) were successfully prepared from stoichiometric mixtures of constituent elements (Si, Al and SiO2) under a nitrogen pressure of 1 MPa by the combustion synthesis (CS) method. The raw materials were combusted with different ratios of a commercial sialon powder of z = 1 as a diluent (0, 10, 20, 30, 40, 50 wt %). Without diluent, the reactions temperatures were very high (> 2000 ?C) and the product contained metal Si residue besides Sialon products. The combustion temperatures of nitridation reactions were controlled by using Sialon (z = 1) as a diluent. The combustion reactions completed at 50 wt% dilution, and pure ?-sialon phases were synthesized. However, the individual peaks of ?-Sialon (z = 1) diluent were also detected. Single-phase ?-sialon powders were obtained by using the products as diluents and repeating the combustion for few times.