A new process is described which permits the sealing of metals to glass and other insulators at temperatures well below the softening point of the glass. Sealing is accomplished in about 1 min by applying a dc voltage in excess of a few hundred volts between the glass and the metal in such a way that the former is at a negative potential with respect to the latter. The process has been applied to a number of glass-metal combinations. A discussion is presented of some of the mechanisms which are believed to play a role in the bonding process.

Thin plates of borosilicate glass were polarized near the annealing point with a dc voltage of typically 600 V. From the measurements of capacitance and current, the width of the polarized region and the electric field within the region were deduced. The results indicate that the glass layer adjacent the anode becomes depleted of positive sodium ions and of compensating negative charge. As a result, the electric field in the layer acquires a maximum value of the order of loo V/cm. Some implications of the process with regard to fieldassisted glass-metal sealing are discussed.

The paper reviews the experimental, theoretical and applications work by several authors on a glass sealing technique which was announced five years ago. In the process, an electrostatic field is utilized to promote bonding at relatively low temperatures. The process variables and seal properties are described in detail. A discussion is presented of the mechanisms which are believed to play a role in bond formation. As an example of the utility of the technique, its highly successful application to the mounting of strain gauges is described.

Evidence is presented that low concentrations of mercury and chlorine vapor in air form reaction products. At constant mercury concentration the rate of formation increases with chlorine concentration and relative humidity. The mercury-chlorine compound as well as the vapor of elemental mercury are absorbed by Hopcalite or by KMnO4-H2SO4 scrubber solution. The compound can be separated from mercury vapor by its absorption in polyurethane or by filtration by means of Millipore aerosol membranes.

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