SYNTHESIS OF AI_4Si_2C_5 AND ITS PHYSICOCHEMICAL PROPERTIES

摘要

When an equimolar powder mixture compact consisting of Al_4C_3 and SiC was heated at 1700°C for 2 h in vacuum, a single phase of Al_4SiC_4 was formed. A fine powder of Al_4SiC_4 after milling with alumina balls for 24 h was sintered using a PECS (Pulse Electric Current Sintering) technique. In the case of heating at 1900°C and then cooling to room temperature with the electric power off, the main crystal phase of the sample changed to Al_4Si_2C_5. The fracture strength, Vickers hardness, and fracture toughness of the dense Al_4Si_2C_5 body were 430 MPa, 14 GPa, and 2.9 MPa-m~(1/2), respectively. The mechanical properties were comparable to those of the dense Al_4SiC_4 body. Further, oxidation resistivity of the dense Al_4Si_2C_5 body has slightly improved compared to that of the dense Al_4SiC_4 body.