Effect of CaO and Al2O3 addition on the properties of K2O–Na2O–P2O5 glass system. (3rd December 2018)

• Record Type: Journal Article
• Authors: Faivre, Annelise; Despetis, Florence; Duffours, Laurent; Colombel, Pascale
• Is Part Of: International journal of applied glass science. Volume 10:Number 2(2019)
• Page Start: 162
• Page End: 171
• Publication Date: 2018-12-03
• Subjects: Glass -- Periodicals; Glass manufacture -- Periodicals; 666.1
• DOI: 10.1111/ijag.13066
• Languages: English
• ISSNs: 2041-1286

Abstract

Abstract: This work reports the effect of substituting Al2 O3 for P2 O5 and substituting CaO for (Na2 O + K2 O) in the ternary 0.46 (K2 O + Na2 O) 0.54 P2 O5 glass system, with certain of these compositions being eventually of interest for biomedical applications. Different properties are analyzed here. When CaO replaces (Na2 O + K2 O; constant O/P ratio) or when Al2 O3 replaces P2 O5 (increasing O/P ratio), it is shown that the density of the glasses increased, the coefficient of thermal expansion decreased, and the glass transition temperature increased. A partial and limited study of dissolution behavior in water indicates that the dissolution rates decreased by orders of magnitude with the introduction of CaO or Al2 O3, in agreement with the trends reported in the literature. The pH values of the dissolution solutions were also measured. The pH quickly decreased and saturated to around 2.5 for glasses with no alumina, that is, with the highest P2 O5 content. On another hand, when Al2 O3 was substituted for P2 O5 (ie, when P2 O5 content decreased and O/P increased), the pH initially increased to more basic values (around 7) and always remained above 5. Some interpretation of the structural role of CaO and Al2 O3 are proposed to explain these changes in properties with composition.