Na-Ra Park

Fabrication of Nanostructured MoSi2-TaSi2 Composite by High-Frequency Induction Heating and its Mechanical Properties

Nanopowders of Mo, Ta and Si were made by high-energy ball milling. A dense nanostructured MoSi2-TaSi2 composite was sintered by the high-frequency induction heated combustion method within 2 minutes from mechanically activated powder of Mo, Ta and Si. A highly dense MoSi2-TaSi2 composite was produced under simultaneous application of a 80 MPa pressure and the induced current. Mechanical properties and microstucture were investigated. The hardness and fracture toughness of the MoSi2-TaSi2 composite were 1200 kg/mm and 3.5 MPa.m, respectively. The mechanical properties were higher than those of monolithic MoSi2. (Received January 3, 2012)

Mechanical Properties and Fabrication of Nanostructured (Ti,Mo)Si2 by Pulsed Current Activated Combustion

Nanopowders of Mo, Ti and Si were made by high-energy ball milling. A dense nanostructured (Ti,Mo)Si2 compound was sintered by the pulsed current activated combustion method within two minutes from mechanically activated powder of Mo, Ti and Si. A highly dense (Mo,Ti)Si2 compound was produced under simultaneous application of 80 MPa pressure and a pulsed current. The mechanical properties and micorostructure were investigated. The hardness and fracture toughness of the (Mo,Ti)Si2 were 1030 kg/mm 2 and 4.9 MPa· m, respectively. The mechanical properties were higher than monolithic TiSi2. (Received February 17, 2011)

Properties and fabrication of nanostructured 2Cr–Al2O3 composite for prosthetic bearing replacements

Cr2O3 and Al powder were used as raw powders, and were milled by the high energy ball milling method. The nanostructured 2Cr-Al2O3 composite from the milled powder was both synthesized and densificated within a short time, by the pulsed current activated sintering (PCAS) apparatus. The relative density of the sintered 2Cr-Al2O3 composite was 99%. The hardness and the fracture toughness of the specimen were 1630 kg/mm(2), and 9.3 MPa·m(1/2), respectively. The weight loss of the composite was measured by a pin-on-disk type apparatus, without a lubricant. Lastly, the 2Cr-Al2O3 composite has a very good cell viability.