No abstract

In this study, the rubber forming process is used to fabricate a micro-channel titanium plate for a PEM fuel cell. The micro-channel plate is fabricated using a 200 ton hydraulic press, and various parameters (punch speed, press pressure, rubber thickness, rubber hardness) are investigated in order to evaluate the formability. TiN films are deposited by reactive DC magnetron sputtering (DCMS) with an electromagnetic field system (EMFS). For the uncoated titanium and TiN-coated titanium substrates, the hardness, surface roughness, and corrosion resistance are estimated by nano-indentation and electrochemical methods, respectively. The improved corrosion resistance of the TiN films can be attributed to the densification of the film caused by enhancement of nitrification with increasing high reactive nitrogen radicals. The uncoated titanium and TiN-coated titanium bipolar plates are combined with a unit cell for a performance test, and respective current densities of 0.396 and 0.888 A cm -2 at 0.6 V are obtained.

In the conventional sand casting process, the size of the riser is made larger than that of the cavity (product part) in order for the molten metal in the riser to solidify at a later stage than the molten metal in the cavity. In this study, a continuous heating method is developed and applied to the riser, using a cylindrical heater, to minimize the size of the riser. A mold having four cavities is designed for casting turbine housings. The height and diameter of the riser are chosen to be 80 mm and 20 mm, respectively. Solidification analysis results, using the analysis program MAGMA soft for casting simulation, showed that when the heater is implemented, the riser is the last to solidify. However, without the heater, the riser solidifies before the cavity, thus causing the riser to function improperly. Moreover, misruns are generated in the casted product if the heater is not implemented, as opposed to the case of a solid product without any defects, with the heater attached in the riser.

This study involves performing direct and indirect hot press forming on ultra-high-strength steel (UHSS) boron steel sheets to determine formability. The indirect hot press process is performed as a cold deep drawing process, while the direct hot press process is performed as a hot deep drawing process. The initial blank temperature and the blank holding force are set as parameters to evaluate the performance of the direct and indirect deep drawing processes. The values of punch load and forming depth curve were obtained in the experiment. In addition, the hardness and microstructure of the boron steel sheets are examined to evaluate the mechanical properties of the material. The forming depth, maximum punch load, thickness, and thinning rate according to blank holding force were examined. The result shows that a larger blank holding force has a more significant effect on the variation of the thickness and thinning rate of the samples during the drawing process. Furthermore, the thinning rate of the deep drawing part in with and without fracture boundary was respectively examined.