On the mechanical properties of lead borate glass

The mechanical properties of lead borate glasses were investigated using ultrasonic wave velocity measurement and nanoindentation. Creep tests at room temperature were performed by holding the indenter at peak load for extended time. Both Youngʹs modulus and nanohardness decreased with increasing PbO molar fraction from 0.35 to 0.75. Creep decreased by increasing PbO from 0.35 to 0.50 mole fraction, and remained relatively unchanged at greater lead concentrations. The variation of Youngʹs modulus with composition was attributed primarily to that of boron coordination number, whereas the variation of creep was attributed to the evolution of lead from glass modifier to former with the increase of lead concentration. Furthermore, the Youngʹs moduli of glasses were predicted using Makishima–Mackenzie model. By considering the effect of cationsʹ coordination numbers on the properties of oxides, marked improvement in the predictions of Youngʹs modulus were made over previous such estimations.