Surface crystallisation behaviour of invert calcium phosphate glasses doped with V_2O_5

摘要

Faculty of Technology and Metallurgy,4 Karnegijeva St.,1 WOO Belgrade,Serbia and MontenegroThe crystallisation behaviour of calcium phosphate glasses with molar ratios of[CaO]/[P_2O_5]-l-2 and V_2O_5 contents of 5-13 mol% is investigated.The results indicate the complex crystallisation behaviour of these glasses,which depends on the V_2O_5 content.The crystallisation of these glasses was detected on DTA(dif-ferential thermal analysis)curves as one or two successive exothermal peaks in the temperature interval T=650-850deg C.The crystallisation temperature peak decreased with increasing V_2O_5 content.alpha-Ca_2P_2O_7 was formed as the primary phase,while beta-Ca_2P_2O_7 and VP_2O_7were formed as the secondary phases.The content of(3-Ca_2P_2O_5 decreased with increasing V_2O_5 content,while that of VP_2O_7 increased.From DTA analysis on powdered glasses and micrographs of fracture surfaces of heat treated bulk glasses it was confirmed these glasses crystallise via surface crystallisation.