Synthesis and Characterization of Al₂O₃-SiC Nano Composite by Sol-Gel Method and the Effect of TiO₂ on Sintering

Abstract

In the present article, α-Al2O3 nano powder was synthesized by a simple aqueous sol–gel method by using AlCl3 as precursor. It was shown that the gel calcined at 1000°C, 1100 °C and 1200 °C resulted in the formation of a crystalline α-Al2O3 nano powder. In continue TEOS and saccharose was used to prepare SiO2 xerogels containing carbon nano particles. The conversion of the gel to β-SiC nano powders was accomplished by carbothermal reduction at 1500°C for 1 h in argon atmosphere. In second pace alumina matrix composites with nano particles of 5 vol% SiC were prepared with the addition of TiO2 as sintering aid and densified by pressureless sintering method at 1600°C and 1630°C for 2 h in nitrogen atmosphere. Green pellets were obtained by uniaxial pressing of 137 MPa. Maximum density (97.3%) was achieved at 1630°C. Vickers hardness was 16.5 GPa after sintering at 1630°C. Scanning electron microscopy revealed that the SiC particles were well distributed throughout the composite matrix. The precursors and the resultant powders were characterized by X-ray diffraction (XRD), thermal analysis (STA) and scanning electron microscopy (SEM).

The Role of Thin-Film Vacuum-Plasma Coatings and Their Influence on the Efficiency of Ceramic Cutting Inserts

“…Square inserts of 12 mm × 12 mm × 4.76 mm made from oxide ceramics strengthened with silicon carbides were used for the conducted experiments. This kind of ceramic has a composite structure which was achieved by adding ceramic powdered SiC to the main powdered Al 2 O 3 in the form of whiskers [25][26][27][28][29][30][31][32]. The whiskers provide higher strength characteristics during sintering.…”