Some Experiments on the Substitution of Lead Oxide in an Alkali–Lead Oxide–Silica Glass for Electrical Purposes

JSGT 1945 V29 T434-T444

 Glass containing 30% of lead oxide is normally used to sheath the current-carrying leads of electric lamps, valves and similar devices. A reduction in the lead content is desirable for many reasons, the problem being to effect this reduction without lowering the electrical resistance at elevated temperatures or raising appreciably the viscosity of the glass. It is shown that the lead oxide content can be reduced to 15% without affecting the electrical resistance, although glasses containing so little lead oxide are slightly harder than the parent glass. Glass containing 20% lead oxide, possessing physical properties similar to the parent glass, can be made by substitution of the lead oxide by small proportions of strontium, barium and magnesium oxides.

J. H. Partridge