Thermal Properties and Water Durability of Glasses in the PbBr_2-PbCl_2-PbF_2-PbO-P_2O_5 System

A series of new glasses in the PbBr2-PbCl2-PbF2-PbO-P2O5 system were prepared and some properties of the glasses in the PbBr2-PbCl2-PbF2-PbO-P2O5 system were studied. Their composition dependence of glass transition temperature(Tg), thermal expansion coefficient and water durability was reported. Glasses in the PbBr2-PbBr2-P2O5 ternary system have relative low glass transition temperature(146℃). When PbO and/or PbF2 are introduced into the ternary system, the glass transition temperature increases considerably. Glasses containing PbO have higher transition temperature than those containing PbF2. The glasses in this system have relative high thermal expansion coefficient(25 x 10-6/℃). Most of the glasses exhibit good water durability, and the dissolution rate in deionised water at 25℃ is in the order of 10-4 ~10-5mm/day. The introduction of PbO and/or PbF2 into the glasses does not change their water durability much. With the increase of P2O5, the water durability of the glass becomes bad obviously.