Upscaled Self-Propagating High-Temperature Synthesis (SHS)/Dynamic Compaction Processing

摘要

Titanium carbide (TiC) and titanium diboride (TiB2) ceramics were formed from elemental powders using a Gleeble 1500 dynamic thermomechanical process simulator. In the first step of a two-step process, a self-propagating high-temperature synthesis (SHS) reaction was initiated by the passage of an electric current through the powdered green body. The temperature of the body was maintained at about 800 deg C, and the reaction rate was controlled by the application of a pressure of about 35 MPa. As verified by x-ray diffraction analysis, this procedure resulted in complete conversion from reactants into products having a range of densities from 72 to 75% of theoretical. In the second step, the current was increased to raise the temperature of the material, thereby sintering and densifying the product. TiC with 3 wt.% nickel (Ni) was sintered to 95 to 98% of theoretical density, while TiC without Ni was sintered to 90% theoretical density. Although TiB2 was successfully converted, efforts to fully densify the product were hindered by the limitations of the Gleeble 1500. The effects of the current and pressure levels on the product density and microstructure were examined. The advantages and limitations of this process are also discussed.