Song-Lee Du

Properties and pulsed current activated consolidation of nanostuctured MgSiO3-MgAl2O4 composites

Nanocrystalline materials have received much attention as advanced engineering materials with improved physical and mechanical properties. As nanomaterials possess high strength, high hardness, excellent ductility and toughness, undoubtedly, more attention has been paid for the application of nanomaterials. Nanopowders of MgO, Al2O3 and SiO2 were made by high energy ball milling. The simultaneous synthesis and consolidation of nanostuctured MgAl2O4-MgSiO3 composites from milled 2MgO, Al2O3 and SiO2 powders was investigated by the pulsed current activated sintering process. The advantage of this process is that it allows very quick densification to near theoretical density and inhibition of grain growth. Highly dense nanostructured MgAl2O4-MgSiO3 composites were produced with a simultaneous application of 80 MPa pressure and a pulsed current of 2000A within 1min. The fracture toughness of MgAl2O4-Mg2SiO4 composites sintered from 60 mol%MgO-20 mol%Al2O3-20mol%SiO2 powders milled for 4 h was 3.2MPa·m1/2. The fracture toughness of MgAl2O4-MgSiO3 composite is higher than that of monolithic MgAl2O4.

Rapid Sintering and Synthesis of Nanostuctured FeCrAlSi-Al_2O_3 Composite by High-Frequency Induction Heating

Nanopowder of Fe2O3, Al, Cr and Si was fabricated by high energy ball milling. A dense nanostuctured A2O3 and 6.06Fe0.33Cr0.16Al0.23Si0.29 composite was simultaneously synthesized and consolidated using high frequency induction heated sintering method within 1 minute from mechanically activated powders of Fe2O3, Al, Cr and Si. The grain sizes of Al2O3 and Fe0.33Cr0.16Al0.23Si0.29 in composite are 80 and 18 nm, respectively. (Received December 1, 2010)

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.

Fabrication of Nanostructured 3FeAl-Al2O3 Composite from Mechanically Synthesized Powders by Pulsed Current Activated Sintering and Its Mechanical Properties

Nanopowder of FeAl and Al2O3 was synthesized from FeO and Al powders by high energy ball milling. Using the pulsed current activated sintering method, the nanocystalline Al2O3 reinforced FeAl composite was consolidated within two minutes from mechanically synthesized powders. The advantage of this process is that it allows very quick densification to near theoretical density and prohibits grain growth in nanostuctured materials. The grain size, sintering behavior and hardness of sintered FeAl-Al2O3 composite were investigated. (Received February 22, 2012)

Rapid Sintering of TiCu by Pulsed Current Activated Heating and its Mechanical Properties

Nanopowder of TiCu was synthesized by high-energy ball milling. A dense nanostructured TiCu was consolidated using a pulsed-current activated sintering method within 1 minute from mechanically synthesized powders of TiCu and horizontally milled powders of Ti+Cu. The grain size and hardness of the TiCu sintered from horizontally milled Ti+Cu powders and high-energy ball-milled TiCu powder were 68 nm, 27 nm and 490 kg/mm, 600 kg/mm, respectively. (Received August 17, 2010)

Mechanical Properties and Fabrication of TiAl Alloy by Pulsed Current Activated Sintering

Nanostuctured TiAl powder was synthesized by high energy ball milling. A dense nanostuctured TiAl was consolidated using pulsed current activated sintering method within 2 minutes from mechanically synthesized powders of TiAl and horizontally milled powders of Ti+Al. The grain size and hardness of TiAl sintered from horizontally milled Ti+Al powders and high energy ball milled TiAl powder were 35 nm, 20 nm and 450 kg/, 630 kg/, respectively.