Fabrication of the Primary Coat of Ceramic Shell Mold for Investment Casting by Electrophoretic Deposition Process

• Main Authors: Jay-Ting Hsieh, 謝杰廷
• Other Authors: Koho Yang
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/08587239410160457622

碩士 === 國立高雄應用科技大學 === 模具工程系碩士班 === 96 === Electrophoretic deposition (EPD) is a process that the charged particles in the colloidal suspension move under the DC field between the two electrodes and coagulate on the opposite electric electrode. The benefits of EPD process are simple facilities, low cost, high deposition rate, and good surface finish. Nowadays, EPD is used widely for the fabrication of ceramic film. In this study, EPD process was used to fabricate ZrO2 primary coat on the conductive plastic, then the primary coat was set for drying after EPD process. The conventional shell building process, ie. dipping and stuccoing were practiced and repeated for several times, till the ceramic shell mold were obtained. The effects of applied voltage, deposition time, dispersant, and polymer on the deposition behavior and suspension were studied. The scanning electron microscope (SEM) was applied to investigate the surface morphology of ZrO2 coating. Both the surface roughness and strength (hot strength, fired strength) of the ceramic shell molds made by EPD process and conventional shell building process were measured and compared by surface roughness tester and MOR tester. The wettability of metal/ceramic shell mold was also analyzed. The results showed that the ZrO2 deposit weight increased with increasing applied voltage. However, the rate of deposition reduced gradually with deposition time. The stability of ceramic suspension could be enhanced by the addition of dispersant and polymer. The ceramic shell mold that fabricated by EPD process showed lower surface roughness and poorer wettability than that of conventional shell building process.