Papers by Author: Gil Ho Hwang

Abstract: The separator of the molten carbonate fuel cells (MCFC) has the major corrosion problems, especially wet-seal area, because this part contacts directly with the corrosive molten carbonate electrolyte. For the protection of the wet-seal area, aluminization method is developed recently. Coated aluminum reacts with the molten carbonate and forms the LiAlO2 having high corrosion resistance, high melting point, no electrical conductivity and no dissolution in molten carbonate. In this study, 50㎛ thickness aluminum foil was applied to form the Al-Fe coating layer on the AISI316L by using the laminating method. Laminating of aluminum foil on AISI 316L was performed at 630°C for 5h in Ar atmosphere using a jig and diffusion heat treatment was carried out at 700°C, 750°C and 800°C for 3h in Ar atmosphere respectively. This method simplified the existing complicated process and has a great advantage of low-cost mass production compared to other methods like PVD, CVD and spray coating.

Abstract: Platinum/Palladium modified aluminide coatings prepared by aluminide pack cementation on the nickel base superalloy Inconnel 738. The platinum/palladium modified aluminide coating of cyclic oxidation behavior at 1200°C was investigated by TGA, XRD and SEM/EDS. Platinum/Palladium modified aluminide coatings showed better cyclic oxidation resistance than Platinum modified aluminide coating and palladium modified aluminide coating compared. Pt and Pd alloy played an enough role in alumina stabilization and in delaying the degradation of β-phase.

Abstract: In this work, we made micromolds using SU-8 photoresist and adopted electroless Ni-P deposition, well known as a hard coating material, to improve the rigidity and durability of SU-8 micromolds. After a micromold using SU-8 was defined by conventional lithography, Ni-P layer was electrolessly deposited on SU-8. By means of electroless Ni-P deposition, it was possible to increase the hardness of a micromold as much as about 17 times. In addition, it will be able to make various sized micromolds with one photomask by regulating the thickness of Ni-P layer.

Abstract: The effects of deformation on corrosion behavior of galvanized steel were investigated. Accelerated corrosion test was conducted under the conditions of 30oC and 90% relative humidity with flowing 200ppm sulfur dioxide gas for five weeks. Surface morphologies and corrosion products were analyzed by SEM/EDS and XRD. The corrosion products were composed of hydrates of ZnSO4. And corrosion rates of each part, bottom, bended and wall, were increased with growing strain due to surface damage and enlargement of naked surface for corrosion.