Vycor fabrication

Two of the flash pyrolysis reactors used for the experiments were fabricated from Amersil T08 commercial grade 50 mm OD quartz tube, and one from 25 mm OD vycor tube (Corning Glass Co.). The flow straightener/female joint was made of quartz for one of the 50 mm OD reactors, and pyrex for the other two reactors. The feeder was made primarily from plexiglas. Teflon tube (6 mm ID) was used to connect the reactor to the pyrex tar trap. 

A second, all quartz 50 mm reactor was immediately fabricated at Princeton and flown to Odeillo to serve as backup for the 25 mm vycor reactor. 

The entire analysis, from digestion to measurement, is performed in a small, easily fabricated, clean Vycor vessel which also serves as an electrochemical cell, thereby eliminating transfer losses and reducing adsorptive losses to a minimum. 

The material selected for the tube or body of the RE must withstand the usage requirements for the electrode as well as the fabrication process. This typically precludes the use of plastics for most hydrogen electrodes as well as the use of glass (and Vycor) for extrane alkaline or hydrofluoric acid (HE) solutions. Table 4.2 lists the general chemical stability of some commonly used materials. 

Besides etching of masked glass substrates, see Sect. 6.1, the leaching of phase-separated glasses, see for instance Figs. 1.14-1.16, is completely an other process and also allows for the fabrication of microstructured glass bodies. A schematic of the process to fabricate a porous glass membrane, which was developed from the classical VYCOR process, is shown in Fig. 6.4. 

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