Oberflächeninitiierte Mikrostrukturbildung in Glaskeramiken
Herstellung und Eigenschaften von Funktionsmaterialien
Zusammenfassung der Projektergebnisse
Using EBSD as primary analysis technique, surface-initiated microstructure formation in glass ceramics was studied extensively within this project. The focus was on preferential orientation caused by oriented nucleation, as well as growth-related effects. Novel analytical approaches and sample preparation techniques were applied to glass ceramics which were subject to highly-defined surface preparation and annealing conditions. As the main result of the project, we found that a strong orientation tendency appears for systems with a strong crystal anisotropy in anisotropic environments. Isotropic crystals would not provide any driving force of crystal orientation even in anisotropic environments. This statement is supported by the observation that this texture is evident even during early growth of separated crystals of ≈ 700 nm in size, not changing during further crystal growth. Hence, crystal orientation seems to result from oriented crystal nucleation rather than from crystal-crystal interactions during early growth or growth-selection phenomena. Based on these results, a theoretical approach to describe oriented nucleation was developed. The interfacial tension was identified as a possible cause of the orientation, and theoretical calculations were carried out to estimate the interfacial tension glass-crystal, taking into account different orientations (faces) of the crystals. For this approach, the bond energy related to different crystal faces was estimated using calculated average crystal fracture surface energies derived from diatomic bond energy. We assume that a minimum energy surface structure will occur during crystal growth, which is equal to the minimum energy cut-surface of this orientation. Therefore, the crystal face with the highest interfacial energy is wetted by the melt, whereas low energy faces can be oriented parallel to the surface. This model was developed for the isochemical surface crystallization of diopside but seems to hold also for other cases like STS-fresnoite, SrAl-silicate crystals, YAG, and cordierite. It fails, however, for BTS-fresnoite. However, during further growth of crystals oriented at nucleation in systems with strong anisotropy, changes in texture may occur. These can be caused, for example, by increasing stresses around the growing crystals. The chemistry surrounding the crystal also plays a significant role, especially in non-stoichiometric systems. This change in orientation was extensively discussed with the Mercator Fellows, and will be implemented in crystal-growth models of Prof. Tonchev. For crystal growth at lower viscosities, also a change of the primarily orientation of the crystals can occur by rotation of the surface crystals caused by interaction with neighbored crystals. Novel sample preparation techniques, aimed at allowing the generation of 3D datasets were developed. Sectioning of a samples with depth-dependent microstructure using initial notches for further, depth-dependent EBSD analysis was successfully demonstrated. In particular, it was shown that smooth surface sections with lowest levels of ion-beam induced amorphization can be created very efficiently. The preparation of XRM pillars was also successfully demonstrated, both in cross-sectional and in-plane geometry.
Projektbezogene Publikationen (Auswahl)
- (2018), ‘Oriented surface nucleation and crystal growth in a 18BaO·22CaO·60SiO2 mol% glass used for SOFC seals’. CrystEngComm, 20, 787
W. Wisniewski, C. Thieme, R. Müller, S. Reinsch, S.-M. Groß-Barsnick, C. Rüssel
(Siehe online unter https://doi.org/10.1039/c7ce02008b) - ‘First hints on reorientation of surface crystals ‘ 92nd Annual Meeting of the German Society of Glass Technology in Conjunction with the Annual Meetings of the Czech Glass Society & the Slovak Glass Society, Bayreuth 2018
C. Tielemann, A. Kirzdörfer, S. Reinsch, R. Müller
- ‘Surface-induced Crystallization of Glass’ Glasforum der Deutschen Glastechnischen Gesellschaft (DGG) 2018
S. Reinsch, R. Müller
- ‘Characterization of early crystallization stages in surface-crystallized diopside glass-ceramics’ 93rd Annual Meeting of the German Society of Glass Technology (DGG) in conjunction with the French Union for Science and Glass Technology (USTV) Annual Meeting, Nürnberg 2019
R. Busch, C. Tielemann, S. Reinsch, C. Patzig, Th. Höche, R. Müller
- ‘Oriented surface crystallization in 18BaO·22CaO·60SiO2 and MgO·CaO·2SiO2 glasses‘ 93rd Annual Meeting of the German Society of Glass Technology (DGG) in conjunction with the French Union for Science and Glass Technology (USTV) Annual Meeting, Nürnberg 2019
S. Reinsch, C. Tielemann, R. Busch, C. Patzig, R. Müller, Th. Höche
- ‘Surface initiated microstructure formation in glass -ceramics‘, DGG-DKG AK Glasig-kristalline Multifunktionswerkstoffe 2019
C. Tielemann, S. Reinsch, C. Patzig, Th. Höche, R. Busch
- ’Surface crystallization of BT0.75S (fresnoite) glass in different atmosphere’ 93rd Annual Meeting of the German Society of Glass Technology (DGG) in conjunction with the French Union for Science and Glass Technology (USTV) Annual Meeting, Nürnberg 2019
M. Fleck, C. Tielemann, F. Scheffler, D. S. Brauer, R. Müller
- 'Crystallization of glasses studied with PEEM'. Joint Meeting of the Polish Synchrotron Radiation Society and SOLARIS Users (2020)1
F. Scheffler, C. Tielemann, R. Busch, M. Kober, Ralf Müller, D. S. Brauer
- (2020), 'Generalised kinetics of overall phase transition useful for glass crystallisation when assuming non-isothermal conditions'. Physics and Chemistry of Glasses-European Journal of Glass Science and Technology Part B, 61[6], p.209-212
I. Avramov, J. Sestak
(Siehe online unter https://doi.org/10.13036/17533562.61.6.006) - ‘On the structural relationship between volume nucleation ability, oriented surface nucleation and interfacial energy’; 94rd Annual Meeting of the German Society of Glass Technology (DGG)
C. Tielemann, R. Müller, S. Reinsch
- ‘Oriented surface crystallization in 18BaO·22CaO·60SiO2 and MgO·CaO·2SiO2 glasses‘; Glass Meeting 2020, Ceramic Society of Japan
C. Tielemann, R. Müller, C. Patzig, Th. Höche, S. Reinsch
- ‘Surface initiated structure formation in glass ceramics‘ XRM Workshop, Halle 2020
R. Busch, R. Müller, C. Patzig, T. Höche, S. Reinsch, C. Tielemann
- (2021), 'Evolution of a notched surface under glancingangle broad ion beam erosion', Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 509, 12-20
R. Busch, M. Krause, Th. Höche
(Siehe online unter https://doi.org/10.1016/j.nimb.2021.09.008) - (2021), 'Oriented surface nucleation in diopside glass'. Journal of Non-Crystalline Solids 562
C. Tielemann, R. Busch, S. Reinsch, C. Patzig, Th. Höche, I. Avramov, R. Müller
(Siehe online unter https://doi.org/10.1016/j.jnoncrysol.2021.120661) - (2021), 'Sample preparation for analytical scanning electron microscopy using initial notch sectioning', Micron 150
R. Busch, C. Tielemann, S. Reinsch, R. Müller, C. Patzig, M. Krause, Th. Höche
(Siehe online unter https://doi.org/10.1016/j.micron.2021.103090)
