Microstructure and Properties of ZrO_2 Toughened MgO-CaO-SiO_2-P_2O_5-CaF_2 Bioactive Glass-Ceramics

Abstract: In this article a series of ZrO_2 toughening MgO-CaO-SiO_2-P_2O_5-CaF_2 bioactive glass-ceramics were obtained by sintering method.XRD,SEM,TEM and FTIR were used to analyze the material structure,mechanical properties and research the material surface behavior when soaked in simulated body fluid for different time.The results showed that there were three types of crystalline phases precipitated from the glass-ceramics with ZrO_2 addition in the high temperature state during the process of sintering,which were Ca_5(PO_4)_3F,β-CaSiO_3 andα-CaSiO_3.After cooling high-temperature phaseα-CaSiO_3 was not found which transformed intoβ-CaSiO_3. The mainly crystalline phases were Ca_5(PO4)_3F andβ-CaSiO_3.The crystallization temperature of every phase declined in some extent with the addition of m-ZrO_2. However,the addition of t-ZrO_2 only caused the crystallization temperatures ofβ-CaSiO_3 andα-CaSiO_3 declined partially,while the crystallization temperature of Ca_5(PO_4)_3F increased.TEM analysis showed that the size of glass-ceramics grain was about 10~20 nm.With the addition of t-ZrO_2,the bending strength of glass-ceramic increased continuously.The bending strength of 5t-GC2444 glass-ceramics(The glass with 5% t-ZrO_2 addition was isothermally treated at 827℃,872℃,911℃and 965℃for 2 h,4 h,4 h and 4 h respectively) achieved the maximum value,which increased 24.86%than that of 0GC2444 glass-ceramics(The glass without ZrO_2 addition was isothermally treated at 700℃,820℃,974℃and 1016℃for 2 h,4 h,4 h and 4 h respectively).At the same time,with the addition of t-ZrO_2 the fracture toughness of glass-ceramics had been greatly increased.The fracture toughnes of 5t-GC2444 glass-ceramics achieved the maximum value,which increased 81.52%than that of 0GC2444 glass-ceramics.So t-ZrO_2 is efficient in improving the fracture toughness of glass-ceramics.However,m-ZrO_2 has played a small role in improving the fracture toughness of glass-ceramics.From the elastic moduluses piont of view,all glass-ceramics are suitable for human bone repair or replacement materials.These glass-ceramics are suitable to be used as coating materials on the surface of titanium or titanium alloys,as their linear expansion coefficients are similar to that of titanium and titanium alloys.When 5t-GC2444 glass-ceramic had been immersed in simulated body fluid for 2 days,hydroxyapatite deposition was found on its surface.21 days later,the surface was covered completely by a thick layer of many granular hydroxyapatites.After 28 days of immersion,the B-type carbonated apatite appeared on the surface of 5t-GC2444 glass-ceramic.Considered from mechnical properties and bioactivity of that 5t-GC2444 bioactive glass-ceramics,which is one kinds of ideal human bone tissue repair substitution material.At the same time,the glass-ceramics are suitable to be used as coating materials of titanium or titanium alloys,so as to further enhance its mechanical properties…
Key words: ZrO_2 toughening; Bioactive; Glass-ceramic/Nucleated glass; Sintering; Fracture toughness

This entry was posted in Master Thesis. Bookmark the permalink.