The Study of Wettability of Water Based Sol-Gel Protective Coatings and It's Applications in Glass Molding

• Main Authors: SV PRABHAKAR VATTIKUTI, 阿偉
• Other Authors: H. H. Chien
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/26317092356028661340

博士 === 中華大學 === 工程科學博士學位學程 === 99 === The glass molding process is considered to have a great potential for the mass production of aspherical and free form glass lenses with high precision and lower cost. In glass molding process, the die surfaces are exposed to chemically active glass and also subjected to mechanical and thermal cyclic operations, which leads to glass sticking and premature failure of the die. This thesis concentrates on the fabrication of glass anti-sticking coatings on dies and glass preforms to solve above mentioned problems via the water based sol-gel dipping approach. The water based sol-gel coatings were selected because of their chemical stability, without shape limitation, high uniformity and low cost. Particular attention was paid to the optimization of the deposition process and post-deposition heat treatment. High temperature glass wetting experiment was carried out to investigate the effects of coatings on high temperature interfacial reaction between the glass gobs and stainless steel substrates. The results show that both the Al2O3 coated stainless steel substrate and glass preforms demonstrated an excellent anti-sticking behavior compared to that of uncoated ones. The Al2O3 film is thermodynamic stable phase and exhibits dense structure which can effectively hinder the out diffusion of active elements from stainless steel and low Tg glasses at high temperature. The time and temperature dependent glass wetting and sticking behavior were investigated. The effect of Al2O3 film coated glass preform on glass lens forming behavior was discussed.