Fabrication of Textured Nb_4AlC_3 Ceramic by Slip Casting in a Strong Magnetic Field and Spark Plasma Sintering

摘要

Textured Nb_4AlC_3 ceramic was successfully fabricated in a strong magnetic field followed by spark plasma sintering. The optimized suspension parameters for slip casting were determined to be 20 vol% Nb_4AlC_3 and 2 wt% polyethyleneimine dispersant of powder in deionized water. After texturing in a strong 12 T magnetic field followed by cold isostatic pressing, the relative green densities were 50.4% and 58.7%, respectively. A dense Nb_4AlC_3 sample was obtained by sintering at 1450℃ under a pressure of 30 MPa in vacuum. X-ray diffraction analysis revealed that the preferred orientation of Nb_4AlC_3 grains parallel to the magnetic field direction was along the c-axis. The Lotgering orientation factors on the textured top surface (TTS) and textured side surface (TSS) were determined to be f_(001) = 0.59 and f_(hko) = 0-64, respectively. The layered texture microstructure contributed to laminar transgranular and intergranular fractures. The indentation response on the TTS showed isotropy and that on the TSS revealed anisotropy.