Effect of B2O3 on crystallization behavior and microstructure of MgO–SiO2–Al2O3–K2O–F glass–ceramics

Pressureless Sintering of Apatite/Wollastonite–Phlogopite Glass–Ceramics

“…Apparently the formation of MgF 2 crystals, in Ph glass, at a relatively low temperature markedly increased the viscosity, retarding the densification process, 13 so as there is no observable sintering and densification occuring at temperatures lower than 940°C, whereas in the case of A/W glasses (Fig. 1) the crystallization occurred at a relatively higher temperature (850°C) allowing the specimen to be sintered to relatively high densities.…”

“…The principle diffraction line of phlogopite was observable up to 1050°C. By increasing the temperature, characteristic XRD peaks of diopside [CaMgSi 2 O 6 with JCPDS identification number (19‐0239)] and melilite [Ca 8 Al 6 MgSi 5 O 28 with JCPDS identification number (04‐0689)] appeared at 1100°C, while XRD peaks of phlogopite disappeared, due to the dissolution of phlogopite at high temperatures 13 . It can be proposed that the dissolution of phlogopite leads to the increase of Al 2 O 3 content in the residual glass assisting the formation of solid solution phases like diopside and melilite.…”

“…Tables I and II summarize the nominal and analytical compositions of two studied glasses designated as A/W and Ph as determined by X‐ray fluorescence. The composition of A/W glass was chosen from the Kokubo et al 's 1 work, and Ph glass was formulated according to a previous study performed by the present authors 13 . The glass batches first were calcined at 900°C for 24 h and then melted at 1450° and 1550°C using Pt crucibles in an electric furnace.…”

“…The composition of A/W glass was chosen from the Kokubo et al's 1 work, and Ph glass was formulated according to a previous study performed by the present authors. 13 The glass batches first were calcined at 9001C for 24 h and then melted at 14501 and 15501C using Pt crucibles in an electric furnace. The melting time was 2 h and melts were poured into cold water to obtain frits.…”

“…The principle diffraction line of phlogopite was observable up to 10501C. By increasing the temperature, characteristic XRD 13 It can be proposed that the dissolution of phlogopite leads to the increase of Al 2 O 3 content in the residual glass assisting the formation of solid solution phases like diopside and melilite. Figure 10 shows the microstructure of specimen C55 heat treated at 10501C for 1 h. The long acicular crystals of wollastonite [CaSiO 3 with JCPDS identification number (42-0550)] and massive crystals of forsterite [Mg 2 SiO 4 with JCPDS identification number (34-0189)] as well as the smaller prismatic crystals of apatite with hexagonal faces are observable.…”