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 r egion is P2O5 greater than or equal to 40, CuO less than or equal to 5 0 and Na2O less than or equal to 60 mol%. Glasses with a glass transit ion temperature (T-g) below 420 degrees C, a thermal expansion coeffic ient 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 ca n be prepared. Substitution of CuO for Na2O increases T-g, the softeni ng temperature (T-d), hardness and chemical durability and decreases t he thermal expansion coefficient. The structure of 50P(2)O(5)-(50 - x) Na2O-xCuO glass was examined by XPS and FTIR spectroscopies, which rev eal 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.