Hyun-Su Kang

Rapid synthesis and consolidation of nanostuctured Al2O3-MgSiO3 composites by high frequency induction heated sintering

Nanopowders of MgO, Al2O3 and SiO2 were made by high energy ball milling. The rapid sintering of nanostuctured Al2O3-MgSiO3 composites was investigated by the high-frequency induction heating sintering process. The advantage of this process is that it allows very quick densification to near theoretical density and inhibits grain growth. Highly dense nanostructured Al2O3-MgSiO3 composites were produced with the simultaneous application of 80 MPa pressure and the induced output current of total power capacity (15 kW) within 2 min. The sintering behavior, grain size and mechanical properties of Al2O3-MgSiO3 composites were investigated.

Pulsed Current Activated Synthesis and Rapid Consolidation of a Nanostructured Mg2Al4Si5O18 and Its Mechanical Properties

Nanocrystalline materials have received much attention as advanced engineering materials, with improved mechanical properties. Attention has been directed to the application of nanomaterials, as they possess excellent mechanical properties (high strength, high hardness, excellent ductility and toughness). A singlestep synthesis and consolidation of nanostructured Mg2Al4Si5O18 was achieved by pulsed current heating, using the stoichiometric mixture of MgO, Al2O3 and SiO2 powders. Before sintering, the powder mixture was high-energy ball milled for 10 h. From the milled powder mixture, a highly dense nanostructured Mg2Al4Si5O18 compound could be obtained within one minute, under the simultaneous application of 80 MPa pressure, and a pulsed current. The advantage of this process is that it allows an instant densification to the near theoretical density, while sustaining the nanosized microstructure of raw powders. The sintering behavior, microstructure and mechanical properties of Mg2Al4Si5O18 were evaluated. The fracture toughness of a nanostructured Mg2Al4Si5O18 compound was higher than that of sub-micron Mg2Al4Si5O18 compound.

Simultaneously rapid synthesis and consolidation of nanostructured Mg0.3Al1.4Ti1.3O5 by high-frequency induction heating

A one-step synthesis and consolidation of nanostructured Mg0.3Al1.4Ti1.3O5 was achieved by high-frequency induction heating, using the stoichometric mixture of MgO, Al2O3 and TiO2 powders. Before sintering, the powder mixture was high-energy ball milled for 10 h. From the milled powder mixture, a highly dense nanostructured Mg0.3Al1.4Ti1.3O5 compound could be obtained within one minute, under the simultaneous application of 80 MPa pressure and an induced current. The advantage of this process is that it allows an instant densification to the near theoretical density, while sustaining the nanosized microstructure of raw powders. The sintering behavior, microstructure and mechanical properties of Mg0.3Al1.4Ti1.3O5 compound were evaluated.

Rapid Sintering of Nanostuctured Tungsten Carbide by High-Frequency Induction Heating and its Mechanical Properties

Extremely dense WC with a relative density of up to 99% was obtained within five minutes under a pressure of 80 MPa using the High-Frequency Induction Heated Sintering method. The average grain size of the WC was about 71 nm. The advantage of this process is not only rapid densification to obtain a neartheoretical density but also the prohibition of grain growth in nano-structured materials. The hardness and fracture toughness of the dense WC produced by HFIHS were 2660 kg·mm and 7.2 MPa·m, respectively. (Received September 6, 2010)

Simultaneous Synthesis and Consolidation of Nanostructured MoSi 2 -NbSi 2 Composite by High-Frequency Induction Heated Sintering and Its Mechanical Properties

The current concern about these materials ( and ) focuses on their low fracture toughness below the ductile-brittle transition temperature. To improve the mechanical properties of these materials, the fabrication of nanostructured and composite materials has been found to be effective. Nanomaterials frequently possess high strength, high hardness, excellent ductility and toughness, and more attention is being paid to their potential application. In this study, nanopowders of Mo, Nb, and Si were fabricated by high-energy ball milling. A dense nanostructured composite was simultaneously synthesized and sintered within two minutes by high-frequency induction heating method using mechanically activated powders of Mo, Nb, and Si. The high-density composite was produced under simultaneous application of 80MPa pressure and an induced current. The sintering behavior, mechanical properties, and microstructure of the composite were investigated. The average hardness and fracture toughness values obtained were and , respectively. These fracture toughness and hardness values of the nanostructured composite are higher than those of monolithic or .