Influence of ZrO2 addition on the crystallization of yttrium oxynitride glasses to Y3Al5O12-based glass-ceramics

Crystallization and microstructures of Y-Si-Al-O-N glass-ceramics containing main crystal phase Y3Al5O12

“…Thus, YAG as major crystalline phase appears in all glass-ceramics prepared in this paper. The result agrees well with the earlier report (Vomacka 1997) that in glass compositions with high nitrogen content (for example 10⋅9 eq.%) the crystallization of YAG dominates from the onset of crystallization around 1100°C, whereas in glass compositions with low nitrogen content (for example 5⋅6 eq.%) it begins to dominate only above 1250°C.…”

“…However, high-temperature properties of yttria-densified β-sialon ceramics can be greatly improved after a postsintering heat treatment because partial or all Y-Si-Al-O-N glasses are converted into a mixture of crystalline phases which are more refractory (Lewis et al 1980;Bentsen et al 1984;Falk and Dunlop 1987). Among these crystalline phases, Y 3 Al 5 O 12 (yttrium alumina garnet, YAG) is the most satisfactory contender for improving high-temperature properties of β-SiAlON materials (Lewis et al 1980;Vomacka 1997). Therefore, the study on the crystallization of YAG from Y-Si-Al-O-N glasses to prepare YAG-based glass-ceramics is of interest.…”

“…A number of investigations (Lewis et al 1980;Leng-ward and Lewis 1985;Bonnell et al 1987;Ding et al 1989;Besson et al 1993;Vomacka and Babushkin 1996;Lemercier et al 1997;Vomacka 1997;Ramesh et al 1998) indicate that YAG as one of the crystalline phases usually appear in many Y-Si-Al-O-N glass-ceramics. These investigations also suggest that the crystallization of YAG from Y-Si-Al-O-N oxynitride glasses depends not only on matrix glass composition but also on heat treatment time and temperature.…”

“…For the glass composition, the content of SiO 2 must be less than 25wt% (Ding et al 1989). For the heat treatment temperature, YAG can be precipitated at temperatures far below 1200°C, but its content is usually small (Besson et al 1993;Vomacka 1997). YAG as the dominant phase usually crystallizes above 1200°C (Bonnell et al 1987;Ding et al 1989;Hampshire et al 1994).…”

“…Note that some other crystal species like apatite (Y 5 Si 3 O 12 N), different forms of Y 2 Si 2 O 7 , intermediate phase and O′-sialon usually crystallize from Y-Si-Al-O-N glasses together with YAG. Y 2 Si 2 O 7 which has five polymorphic forms sometimes can even be the dominant phase (Vomacka 1997). Phase transformations of Y 2 Si 2 O 7 or intermediate phase in certain case can cause problems such as the thermal and the volume effects.…”