My Work
My broad interests in materials science and engineering relate to mechanical engineering (multifunctional structural materials, smart materials, composite materials, thermal management, energy harvesting), civil engineering (concrete), electrical engineering (electronic packaging, sensors) and chemical engineering (batteries, fuel cells, activated carbon, filter membranes). Multidisciplinary research, practical applications and new material development are emphasized. Since the early 1990s, the research has involved nanomaterials.
My Research
Nanostructured thermal interface materials for improving thermal contacts, as needed for microelectronic cooling
Carbon black, fumed metal oxides, nanoclay and graphite nanoplatelet are more effective than carbon nanotube for formulating thermal pastes, though all are in the nanoscale. Carbon black and fumed metal oxides are particularly effective, due to their conformability.
Structural materials for civil and aerospace structures
- Nanostructuring the interlaminar interface of a continuous fiber polymer-matrix composite is studied to improve the through-thickness thermal conductivity (as needed for aircraft heat dissipation), the mechanical properties, and the capacitance (as needed for electrical energy storage). Carbon black as an interlaminar filler is more effective than carbon nanotube array or graphite nanoplatelet for increasing the through-thickness thermal conductivity. Carbon nanotube and graphite nanoplatelet are effective for enhancing vibration damping. Fumed alumina is effective for enhancing the capacitance.
- Silica fume as a nanoscale admixture in cement-based materials is effective for enhancing the corrosion resistance of embedded steel rebar, the bond strength with steel rebar, the vibration damping capacity, the mechanical properties and the abrasion resistance .
Microwave materials for electromagnetic (EMI) shielding
Nanotechnology is valuable due to the skin effect. Nickel nanofiber remains today the most effective filler for polymer-matrix composites for shielding.
Electrode materials for MEMS, batteries, fuel cells and double-layer capacitors
- Carbon nanofiber is superior to carbon black in lithium primary cell that uses carbon as a porous electrode (current collector) and as an electrically conductive additive in a non-conducting electrode.
- Carbon nanofiber sheet is thinner than carbon black sheet, thereby enhancing the energy density of lithium primary cell.
- The packing density is lower for carbon nanofiber sheet than carbon black sheet, thereby increasing the electrolyte absorptivity and hence increasing the energy density of lithium primary cell.
- Carbon nanofiber in place of carbon black as conductive additive in MnO2 cathode of a lithium primary cell causes the running voltage near the cell end-of-life to decline gradually (not abruptly), due to high electron transfer rate and the high rate of electrolyte absorption.
- Graphitized carbon nanofiber is particularly effective as a conductive additive in the MnO2 cathode.
Environmental materials for fluid purification (adsorption and filtration), filters, molecular sieves and membranes
- Mesoporous activated carbon nanofiber
- Porous carbons made from carbon nanofiber
*All of the above findings are the results of Dr. Chung’s nanomaterials research from 1996-Present.