Synthesis of a SiC-SiAlON Composite by Nitridation of a SiC-AlSi Mixture

摘要

SiC-SiAlON composite was produced from a mixture of SiC powders with wide particle size distribution and Al-34Si alloy powder by nitridation. The aluminum-silicon alloy was produced by the mechanical alloying method. The composition studied was 75 wt/100 SiC and 25 wt/100 (Al. 34Si). The powder was compacted by uniaxial and cold isostatic pressing, forming tablets 25 mm in diameter and 10 mm thick. These tablets were then nitridized in a graphite resistance furnace. The heating rate up to 1000deg.C was 20deg.C/min, and 10deg.C/min up to 1400deg.C. Dwelltime at 1400deg.C was 8 hours. Thermodynamic analysis of the system was accomplished. Powders of raw materials were characterized by sedimentation analysis, chemical analysis, scanning electron microscopy, and X- ray diffraction. The material obtained after nitridation was characterized by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. The porosity and final density were determined by gas picnometry.