Thermal and corrosion behavior of P2O5-Na2O-CuO glasses

Lead free sodium-copper-phosphate glasses in the range (mol%) 30-80P(2)O(5), 0-70Na(2)O and 0-70CuO were investigated. The glass formation region is P2O5 greater than or equal to 40, CuO less than or equal to 50 and Na2O less than or equal to 60 mol%. Glasses with a glass transition temperature (T-g) below 420 degrees C, a thermal expansion coefficient from 258 X 10(-7) to 99 X 10(-7)/degrees C and a dissolution rate in 30 degrees C deionized water at the order of 10(-7) g/cm(2) min can be prepared. Substitution of CuO for Na2O increases T-g, the softening temperature (T-d), hardness and chemical durability and decreases the thermal expansion coefficient. The structure of 50P(2)O(5)-(50 - x)Na2O-xCuO glass was examined by XPS and FTIR spectroscopies, which reveal the formation of P-O-Cu bonds in these glasses. The formation of P-O-Cu bonds, which replace P - O-... Na+ bonds while keeping the same fraction of P-O-P bonds, increases the crosslink density in the glass network and, therefore, enhances the chemical durability and increases T-g, T-d and the hardness of the glasses. (C) 1998 Elsevier Science B.V.