Design of an evaporator for vaporization of glass forming silica precursor

Use of silicon tetrachloride (SiCl4) for high purity glass forming silica is very convenient due it its high vapor pressure. However, in presence of oxy-hydrogen flame, it forms hydrochloric acid (HCl) which creates environmental hazard. In contrast, halogen free organometallic precursor such as Octamethylcyclotetrasiloxane (OMCTS) is a promising alternative. However, evaporation process of OMCTS is only available the patent literature with considerable gaps in the scientific understanding in open literature. In this work, property of OMCTS is studied and analyzed the different patented designs of Corning Inc. A packed bed evaporator is designed and fabricated. Different experiments were conducted and tested for performance of the designed evaporator. The designed evaporator can generate very highly pure OMCTS vapor required for high purity silica glass. Unlike previous observations mentioned in the available patent literature, there was no high molecular specie was observed in the residue of the designed evaporator.