The reuse of waste materials in high quality applications is of high economic and ecologic importance. Glassy materials from end-of-life cathode ray tubes (CRT) in this context come in several fractions: panel or screen glass (ca. 2/3 by weight, major content of BaO and SrO), funnel glass (ca. 1/3 by weight, up to 25% PbO), neck glass (up to 40% PbO) and solder glass (up to 85% PbO). The PbO-containing fractions can be processed to metallic Pb, while for screen glass there is no further use at present. Therefore, preprocessing of this fraction (to get rid of the heavy metal content) and its potential use in dielectric binders (e.g. for AC-electroluminescence) are reported in this work.
Preprocessing of the milled glass fraction proceeds at elevated temperature in moist atmosphere and reduces the Ba- and Sr-content in the surface layer of the powder particles. The final activated glass powder is formulated with polymeric binders and sintering aids on borate base to a printable paste. Commercial AC-electroluminescent ZnS powder was worked into this paste, and finally small AC-electroluminescent units were fabricated from this multifunctional composite by tape-casting on ITO glass and application of carbon back electrodes. Morphological as well as optical data of these structures are reported. Future work will concentrate on improvements in homogeneity, area, emission intensity and durability. Since the binder is of inorganic nature, high temperature resistant structures on glass will be fabricated as well.
The results thus show, that a problematic waste material may be transformed into a multifunctional material of high economic value by comparable simple processing.