Pub Date : 2024-08-09DOI: 10.52825/glass-europe.v2i.1320
Jonas Hildebrand, Christian Roos
A setup for thermal poling treatment of glass and glass-ceramic via gas discharge using an open electrode configuration was built and tested successfully. In the setup a thin Pt-wire is used as a top electrode with adjustable distance to the glass sample. The glass rests on a Pt-sheet acting as bottom electrode which again rests on transporting rolls made of alumina. The setup is implemented in a specially built furnace in which the sample is moved underneath the static wire electrode. With this setup, lithium-aluminosilicate (LAS) glass samples were thermally poled at 200 °C for 20 min, 60 min and 180 min with discharge currents ranging from 25 µA to 300 µA. Over time the process gets more unstable but without any major breakdowns. The measured crystallinity at the anode side surface of the post-poling ceramised samples shows a decrease with both treatment time and poling current (i.e. electrical field strength). This is explained with the depletion of Li from the anode side surface layer which becomes stronger with higher electrical fields and continues over time. In scanning electron microscopy (SEM) images of cross sections of the anode sides a mostly glassy layer is observed which adds to the point aforementioned. As a key result this work proved that with an open electrode setup for thermal poling treatments of LAS glasses similar results can be achieved as with a blocking setup. This opens the door to the modification of glasses and corresponding glass-ceramics in an inline and continuous process that can be used industrially.
利用开放式电极配置，通过气体放电对玻璃和玻璃陶瓷进行热极化处理的装置已经建立并测试成功。在该装置中，一根细铂丝被用作顶电极，与玻璃样品的距离可调。玻璃放在作为底电极的铂片上，而铂片又放在氧化铝制成的运输辊上。该装置在一个特制的熔炉中实施，样品在静态金属丝电极下方移动。利用这种装置，锂铝硅酸盐（LAS）玻璃样品在 200 °C 下分别进行了 20 分钟、60 分钟和 180 分钟的热极化，放电电流从 25 µA 到 300 µA。随着时间的推移，该过程变得越来越不稳定，但没有出现任何重大故障。极化后陶瓷样品阳极侧表面的结晶度测量结果显示，随着处理时间和极化电流（即电场强度）的延长，结晶度都在下降。这是因为阳极侧表层的锂损耗随着电场强度的增加而增强，并随着时间的推移而持续。在阳极侧横截面的扫描电子显微镜（SEM）图像中，可以观察到大部分为玻璃层，这进一步证实了上述观点。这项工作的主要成果证明，采用开放式电极设置对 LAS 玻璃进行热极化处理，可以获得与阻塞式设置类似的结果。这为玻璃和相应的玻璃陶瓷的改性打开了一扇门，使其成为一种可用于工业的在线连续工艺。
{"title":"Open Electrode Thermal Poling Setup for Treating Lithium-Aluminosilicate Glass-Ceramics Using Gas Discharge","authors":"Jonas Hildebrand, Christian Roos","doi":"10.52825/glass-europe.v2i.1320","DOIUrl":"https://doi.org/10.52825/glass-europe.v2i.1320","url":null,"abstract":"A setup for thermal poling treatment of glass and glass-ceramic via gas discharge using an open electrode configuration was built and tested successfully. In the setup a thin Pt-wire is used as a top electrode with adjustable distance to the glass sample. The glass rests on a Pt-sheet acting as bottom electrode which again rests on transporting rolls made of alumina. The setup is implemented in a specially built furnace in which the sample is moved underneath the static wire electrode. With this setup, lithium-aluminosilicate (LAS) glass samples were thermally poled at 200 °C for 20 min, 60 min and 180 min with discharge currents ranging from 25 µA to 300 µA. Over time the process gets more unstable but without any major breakdowns. The measured crystallinity at the anode side surface of the post-poling ceramised samples shows a decrease with both treatment time and poling current (i.e. electrical field strength). This is explained with the depletion of Li from the anode side surface layer which becomes stronger with higher electrical fields and continues over time. In scanning electron microscopy (SEM) images of cross sections of the anode sides a mostly glassy layer is observed which adds to the point aforementioned. As a key result this work proved that with an open electrode setup for thermal poling treatments of LAS glasses similar results can be achieved as with a blocking setup. This opens the door to the modification of glasses and corresponding glass-ceramics in an inline and continuous process that can be used industrially.","PeriodicalId":130330,"journal":{"name":"Glass Europe","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141923022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-03DOI: 10.52825/glass-europe.v2i.1187
A. C. Contreras Jaimes, Gloria Kirste, Christian Patzig, J. Martins de Souza e Silva, J. Massera, N. Karpukhina, Robert G. Hill, A. de Pablos-Martín, D. Brauer
A combination of XRD, solid-state NMR and state-of-the-art imaging techniques were used to investigate how the calcium orthophosphate/calcium silicate ratio affects the crystallisation of bioactive glasses in the system SiO2-P2O5-CaO-CaF2. In the phosphate-free glass, xonotlite, wollastonite and cuspidine crystallised. From 2.4 mol% P2O5, fluorapatite also formed, while the amount of wollastonite decreased. Crystallisation tendency was low for low phosphate contents, while above 3 mol% P2O5 it increased. The phosphate-free glass showed a volume crystallisation mechanism with constant activation energy. By contrast, the glass with the largest phosphate to silicate ratio showed both volume and surface crystallisation, causing a pronounced decrease in activation energy with crystallisation degree. This work shows that by changing the phosphate/silicate ratio we can determine which crystal phases form, obtaining for example fluorapatite-free or wollastonite-free glass-ceramics, depending on the desired application and properties such as mechanical strength or activity in contact with physiological solutions.
{"title":"Phosphate/Silicate Ratio Allows for Fine-Tuning of Bioactive Glass Crystallisation and Glass-Ceramic Microstructure","authors":"A. C. Contreras Jaimes, Gloria Kirste, Christian Patzig, J. Martins de Souza e Silva, J. Massera, N. Karpukhina, Robert G. Hill, A. de Pablos-Martín, D. Brauer","doi":"10.52825/glass-europe.v2i.1187","DOIUrl":"https://doi.org/10.52825/glass-europe.v2i.1187","url":null,"abstract":"A combination of XRD, solid-state NMR and state-of-the-art imaging techniques were used to investigate how the calcium orthophosphate/calcium silicate ratio affects the crystallisation of bioactive glasses in the system SiO2-P2O5-CaO-CaF2. In the phosphate-free glass, xonotlite, wollastonite and cuspidine crystallised. From 2.4 mol% P2O5, fluorapatite also formed, while the amount of wollastonite decreased. Crystallisation tendency was low for low phosphate contents, while above 3 mol% P2O5 it increased. The phosphate-free glass showed a volume crystallisation mechanism with constant activation energy. By contrast, the glass with the largest phosphate to silicate ratio showed both volume and surface crystallisation, causing a pronounced decrease in activation energy with crystallisation degree. This work shows that by changing the phosphate/silicate ratio we can determine which crystal phases form, obtaining for example fluorapatite-free or wollastonite-free glass-ceramics, depending on the desired application and properties such as mechanical strength or activity in contact with physiological solutions.","PeriodicalId":130330,"journal":{"name":"Glass Europe","volume":"13 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141272093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-06DOI: 10.52825/glass-europe.v1i.890
Crystal Guillet, Rafael José Jiménez-Riobóo, Francisco Muñoz
The resistance to thermal shock is one of the main properties to be considered in the design of glasses for their application as high power and high energy laser glasses. Neodymium doped phosphate glasses have inherent spectroscopic advantages for their use as laser hosts, however, their rather low mechanical performance can be a limiting factor for their use. It is very important to characterise the thermo-mechanical resistance of proprietary phosphate glass compositions as laser glasses, however, it is not common to find systematic studies on the influence of glass composition on the thermal shock resistance in phosphate glasses, which is defined as the mechanical resistance of the material to the stresses generated by thermal fluctuations. This includes considering the elastic properties of the medium, its thermal conductivity, the coefficient of thermal expansion and the fracture toughness. In the present work we have studied these properties in a series of alumino-phosphate glasses doped with Nd2O3 as a function of the alumina content. The above properties have been determined by Brillouin spectroscopy, dilatometry and thermal diffusivity, while the fracture toughness has been approached by means of a theoretical model that uses the calculation of the energy necessary to create a new surface while a pre-existing crack progresses. The results showed that the calculated fracture toughness agrees with the one of similar commercial laser glass compositions, and that the thermal shock resistance calculated in the metaphosphate glasses increases with the addition of Al2O3.
{"title":"Assessment of the Thermal Shock Resistance of Neodymium Doped Alumino-Phosphate Laser Glasses","authors":"Crystal Guillet, Rafael José Jiménez-Riobóo, Francisco Muñoz","doi":"10.52825/glass-europe.v1i.890","DOIUrl":"https://doi.org/10.52825/glass-europe.v1i.890","url":null,"abstract":"The resistance to thermal shock is one of the main properties to be considered in the design of glasses for their application as high power and high energy laser glasses. Neodymium doped phosphate glasses have inherent spectroscopic advantages for their use as laser hosts, however, their rather low mechanical performance can be a limiting factor for their use. It is very important to characterise the thermo-mechanical resistance of proprietary phosphate glass compositions as laser glasses, however, it is not common to find systematic studies on the influence of glass composition on the thermal shock resistance in phosphate glasses, which is defined as the mechanical resistance of the material to the stresses generated by thermal fluctuations. This includes considering the elastic properties of the medium, its thermal conductivity, the coefficient of thermal expansion and the fracture toughness. In the present work we have studied these properties in a series of alumino-phosphate glasses doped with Nd2O3 as a function of the alumina content. The above properties have been determined by Brillouin spectroscopy, dilatometry and thermal diffusivity, while the fracture toughness has been approached by means of a theoretical model that uses the calculation of the energy necessary to create a new surface while a pre-existing crack progresses. The results showed that the calculated fracture toughness agrees with the one of similar commercial laser glass compositions, and that the thermal shock resistance calculated in the metaphosphate glasses increases with the addition of Al2O3.","PeriodicalId":130330,"journal":{"name":"Glass Europe","volume":"58 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138596840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-23DOI: 10.52825/glass-europe.v1i.681
Roger Gomes Fernandes, R. Al-Mukadam, H. Bornhöft, S. Reinsch, Ralf Müller, Susanne Selle, J. Deubener
The process of viscous flow sintering is a phenomenon that is closely linked to the surface properties of the glass particles. In this work, we studied the extreme case of acid-leaching of soda-lime-silicate glass beads of two different particle size distributions and its effects on non-isothermal viscous sintering of powder compacts. Depth profiling of the chemical composition after leaching revealed a near-surface layer depleted in alkali and alkaline earth ions, associated with concurrent hydration as mass loss was detected by thermogravimetry. Heating microscopy showed that acid treatment of glasses shifted the sinter curves to higher temperatures with increasing leaching time. Modelling of the shrinkage with the cluster model predicted a higher viscosity of the altered surface layer, while analysis of the time scales of mass transport of mobile species (Na+, Ca2+ and H2O) during isochronous sintering revealed that diffusion of Na+ can compensate for concentration gradients before sintering begins. Also, exchanged water species can diffuse out of the altered layer, but the depletion of Ca2+ in the altered surface layer persists during the sinter interval, resulting in a glass with higher viscosity, which causes sintering to slow down.
{"title":"Viscous Sintering of Acid Leached Glass Powders","authors":"Roger Gomes Fernandes, R. Al-Mukadam, H. Bornhöft, S. Reinsch, Ralf Müller, Susanne Selle, J. Deubener","doi":"10.52825/glass-europe.v1i.681","DOIUrl":"https://doi.org/10.52825/glass-europe.v1i.681","url":null,"abstract":"The process of viscous flow sintering is a phenomenon that is closely linked to the surface properties of the glass particles. In this work, we studied the extreme case of acid-leaching of soda-lime-silicate glass beads of two different particle size distributions and its effects on non-isothermal viscous sintering of powder compacts. Depth profiling of the chemical composition after leaching revealed a near-surface layer depleted in alkali and alkaline earth ions, associated with concurrent hydration as mass loss was detected by thermogravimetry. Heating microscopy showed that acid treatment of glasses shifted the sinter curves to higher temperatures with increasing leaching time. Modelling of the shrinkage with the cluster model predicted a higher viscosity of the altered surface layer, while analysis of the time scales of mass transport of mobile species (Na+, Ca2+ and H2O) during isochronous sintering revealed that diffusion of Na+ can compensate for concentration gradients before sintering begins. Also, exchanged water species can diffuse out of the altered layer, but the depletion of Ca2+ in the altered surface layer persists during the sinter interval, resulting in a glass with higher viscosity, which causes sintering to slow down.","PeriodicalId":130330,"journal":{"name":"Glass Europe","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139245795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-16DOI: 10.52825/glass-europe.v1i.435
Gohar Sani, Roman Sajzew, R. Limbach, S. Sawamura, A. Koike, L. Wondraczek
Chemical strengthening by diffusive ion exchange (IOX) is a common method to improve the mechanical performance of glass products. However, the process of ion-stuffing is often associated with an increase of surface hardness and a decrease of the resistance to abrasive wear during scratching, even when the thickness of the exchanged layer is low. Autoclave steam-treatment presents a way to compensate the enhanced surface brittleness accompanying IOX. It causes a notable shift in the load threshold for microabrasion to more abrasion-resistant glasses. Subject to the specific processing parameters, the softening effect is constrained to a surface layer of less than 500 nm in thickness; therefore, the overall compressive stress profile is not affected and the advantages of IOX strengthening are retained. In turn, ion-stuffing by IOX counteracts severe autoclave corrosion of soda-lime silicate glasses, making them suitable for a combination of both processes.
{"title":"Surface Hardness and Abrasion Threshold of Chemically Strengthened Soda-Lime Silicate Glasses After Steam Processing","authors":"Gohar Sani, Roman Sajzew, R. Limbach, S. Sawamura, A. Koike, L. Wondraczek","doi":"10.52825/glass-europe.v1i.435","DOIUrl":"https://doi.org/10.52825/glass-europe.v1i.435","url":null,"abstract":"Chemical strengthening by diffusive ion exchange (IOX) is a common method to improve the mechanical performance of glass products. However, the process of ion-stuffing is often associated with an increase of surface hardness and a decrease of the resistance to abrasive wear during scratching, even when the thickness of the exchanged layer is low. Autoclave steam-treatment presents a way to compensate the enhanced surface brittleness accompanying IOX. It causes a notable shift in the load threshold for microabrasion to more abrasion-resistant glasses. Subject to the specific processing parameters, the softening effect is constrained to a surface layer of less than 500 nm in thickness; therefore, the overall compressive stress profile is not affected and the advantages of IOX strengthening are retained. In turn, ion-stuffing by IOX counteracts severe autoclave corrosion of soda-lime silicate glasses, making them suitable for a combination of both processes.","PeriodicalId":130330,"journal":{"name":"Glass Europe","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129759162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-26DOI: 10.52825/glass-europe.v1i.425
S. Reinsch, T. Welter, R. Müller, J. Deubener
The permeation of hydrogen gas was studied in meta-aluminous (tectosilicate) glass powders of Li2O×Al2O3×SiO2 (LAS), Na2O×Al2O3×SiO2 (NAS) and MgO×Al2O3×SiO2 (MAS) systems by pressure loading and vacuum extraction in the temperatures range 210–310 °C. With this method, both the solubility S and the diffusivity D were determined, while the permeability was given by the product SD. For all glasses, S was found to decrease with temperature, while D increased. Since the activation energy of diffusion of H2 molecules exceeded that of dissolution, permeation increased slightly with temperature. When extrapolated to standard conditions (25 °C), the permeability of tectosilicate glasses was found to be only 10-22–10-24 mol H2 (m s Pa)-1, which is 8–10 magnitudes lower than most polymers. Thin glass liners of these compositions are expected to be the most effective barrier for tanks of pressurised hydrogen.
{"title":"Hydrogen Permeability of Tectosilicate Glasses for Tank Barrier Liners","authors":"S. Reinsch, T. Welter, R. Müller, J. Deubener","doi":"10.52825/glass-europe.v1i.425","DOIUrl":"https://doi.org/10.52825/glass-europe.v1i.425","url":null,"abstract":"The permeation of hydrogen gas was studied in meta-aluminous (tectosilicate) glass powders of Li2O×Al2O3×SiO2 (LAS), Na2O×Al2O3×SiO2 (NAS) and MgO×Al2O3×SiO2 (MAS) systems by pressure loading and vacuum extraction in the temperatures range 210–310 °C. With this method, both the solubility S and the diffusivity D were determined, while the permeability was given by the product SD. For all glasses, S was found to decrease with temperature, while D increased. Since the activation energy of diffusion of H2 molecules exceeded that of dissolution, permeation increased slightly with temperature. When extrapolated to standard conditions (25 °C), the permeability of tectosilicate glasses was found to be only 10-22–10-24 mol H2 (m s Pa)-1, which is 8–10 magnitudes lower than most polymers. Thin glass liners of these compositions are expected to be the most effective barrier for tanks of pressurised hydrogen.","PeriodicalId":130330,"journal":{"name":"Glass Europe","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116858564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：