Effect of Cr content on the SHS reaction of Cr-Ti-C system

摘要

The effect of Cr content on the self-propagating high temperature synthesis (SHS) reaction of Cr-Ti-C system has been investigated in this research. The thermodynamics calculation indicates that the TiC possesses higher thermodynamic stability than the Cr_(23)C)6, Cr_7C_3 and Cr_33C_2 phases, and the formation of TiC is the most exothermic. Additionally, the adiabatic combustion temperature (T_(ad)) decreases with the increase of Cr content except for the phase transition regions. The XRD result shows that the type of products synthesized by SHS changes that a higher Cr content corresponds to higher chromium carbide. When Cr content is 10 wt. percent, only solid solution (Ti,Cr)C_(ss) is formed in the products. When Cr content increases to 20 wt. percent, besides (Ti,Cr)C_(ss), the Cr_7C_3 phase is also detected. With the Cr content further increasing to 30 and 40 wt. percent, the products consist of (Ti,Cr)C_(ss), Cr_(23)C_6, Cr_7C_3 and Cr, and therefore, much higher chromium carbide is synthesized. When Cr content reaches 50wt. percent, however, the Cr_7C_3 disappears and the final products become (Ti,Cr)C_(ss), Cr_(23)C_6 and Cr. Moreover, when Cr content increases from 10 to 20 wt. percent, the lattice parameter of (Ti,Cr)C_(ss) decreases, while it increases when the Cr content ranges from 20 to 50 wt. percent. Furthermore, the microstructure shows that the TiC particulate size decreases from approx 8 to approx 2 mu m with the increase of Cr content from 10 to 50 wt. percent, and the morphology shape of TiC particulate becomes more and more spherical.