Laser sealed evacuated window glazings

The design and fabrication of a highly insulating, evacuated window glazing were investigated. A thermal network model was used to parametrically predict the thermal performance of such a window. Achievable design options are predicted to provide a glazing with a thermal conductance less than 0.6 W/sq m K which is compact, lightweight and durable. A CO2 laser was used to produce a continuous, leak tight, welded glass perimeter seal around 25 x 25 sq cm test specimens. Various diameters of regularly spaced spherical support spacers were incorporated in the specimens as well as an integral SnO2:F transparent, low emissivity coating for suppression of radiative heat transfer. Laser sealing rates of .06 cm/s were achieved at a 580 C glass working temperature with 400 W of continouous wave (CW) laser power.