Studying change of Carbide Precipitate during Creep Test of 2.25Cr-Mo Steel-–. The work is based on the quantitative analysis of the change of precipitate free zone in microstructures during creep test to develop Remanent Assessment Method for high temperature working components in power plant. In detail, to determine the change of fraction and width of precipitate free zone near to grain boundary which was caused by carbide precipitation in grain boundary and ferrite matrix, under effect of exposed temperature and time. Then, the relationship between fraction and width of precipitate free zone and Larson-Miller Parameter (LMP) are established. Moreover, kinetics of the growth of the width is studied to model the microstructural evolution. The relationship between width and mechanical properties such as the creep damage (fracture stress) is evaluated to determine safety working area for components.
Investigation of oxidation behavior and crack healing ability Mo/Al2O3 hybrid materials- Research work in Japan (1-3/2010) (as a visiting researcher)-: the oxidation behavior of 5 vol% Mo/Al2O3 hybrid materials was investigated at high temperatures in air. The apparent activation energy of the parabolic rate constant was equal to 95 kJmol-1.
Synthesis of Cu matrix - nano Al2O3 strengthened composite for electrode materials: Cu-Al2O3 nanocomposites-Research work in Vietnam 2007-2012 (as teaching and researching staff): investigation of process for preparing green compact from Cu- Al2O3 with various content of Al2O3 nanocomposites powder synthesized by a mechanochemical process. The results showed that nano Al2O3 with particles size of 50 nm was formed and distributed in Cu matrix. The process was carried out by atrittor and conventional ball mixing method.
Synthesis of Porous Nitinol: Porous NiTi (Nitinol) for bio-application was synthesized by Self-propagating high temperature reaction. The microstructure showed that the SHS’ product has higher open and connected pores where would be the space for human muscle growth. The phase of transformation was studied by using X-ray and SEM.
Fabrication of the Cu-TiB2 nanocomposites-Research-work in Korea 2004-2007 (as a Ph.D student): To study fabrication of the Cu-TiB2 nanocomposites with high electrical conductivity, strength and high temperature stability materials by a combined process of mechanical activation (MA), self-propagating high-temperature synthesis (SHS) and spark-plasma sintering (SPS). The results showed that there were Cu and TiB2 peaks in the XRD pattern of SHSed product and the TiB2 particles with the mean size of smaller than 250nm were formed in copper matrix. The hardness increased up to 78 HRB, ii the electrical conductivity: 79%IACS, the ultimate tensile strength: 524 MPa and vicker’s hardness: 143. The mechanical and electrical conductivity of SM materials satisfied with KSD 5579. The softening temperature was 600oC and some volume expansion occurred after heating the sintered sample to high temperature.
Study the oxidation behavior of Ni/Al2O3 composites at high temperatures - Research work in Japan 2001-2002 (as master student): The oxidation behavior of Al2O3-based composites with a 5 vol% Ni particle dispersion was investigated at high temperatures in air. The oxidized layer consisted of Al2O3 and NiAl2O4. The growth of the oxidized layer followed a parabolic manner, which means that mass transport in the oxidized layer was the rate-controlling process. The value of the parabolic rate constant at 1300°C was 1.8×10-14 m2s-1. The mechanism of oxidation behavior was discussed in the work.