Fabrication of Nanosized Al₂O₃ Coated Reinforcing Particle Using Electrostatic Force

Titanium carbide (TiC) particles have been coated with aluminum (Al) phase to enhance the compatibility with a metal matrix based on Al, expecting the homogenous dispersion of TiC particles into the matrix. The TiC particles were uniformly dispersed in the aqueous solution of pH 12. The aluminum nitrate as a precursor of Al phase was added to the solution dispersed with the TiC particles. The coating of Al phase onto the TiC particle was driven by the attractive force between the TiC particle with a negative charge and the Al cation in the aqueous solution. The TiC was not oxidized after heat treatment at 500 °C, whereas titanium dioxide peaks are detected after heat treatment at 1000 °C. In addition, the Al phase coated on the TiC surface was converted to amorphous alumina (Al₂O₃) and crystallized into α-Al₂O₃ during heat treatment at 500 and 1000 °C, respectively. The heat treatment condition such as atmosphere and temperature was an important factor in fabricating the reinforcing particles without degradation such as oxidation and phase transformation. The nano-sized Al₂O₃ coated reinforcing particles could be well fabricated using electrostatic force in the aqueous solution and by controlling the heat treatment condition.