Thermal strengthening of low‐expansion glasses and thin‐walled glass products by ultra‐fast heat extraction

Abstract

Mechanical performance and consumer product safety have been major drivers for glass research and innovation. Commodity glass materials are brittle and, thus, their mechanical performance is extremely sensitive to the presence of microscopic flaws and defects at their surface: the extent by which surface flaws reduce the practical strength of glass products exceeds the effect of any optimization in glass composition by several orders of magnitude. 1 Strength-reducing flaws are created already during glass manufacture 2,3 : the intrinsic strength levels which are expected from theoretical considerations can be approached experimentally only on carefully drawn glass fibers which are basically free of microscopic defects. 4,5 For other types of glass products, processes such as acid-or fire-polishing are often applied in order to create defect-free surfaces. Such post-processing does not only reduce the presence of surface defects or flaws on pristine glass articles, but may also lead to a more persistent enhancement of product durability by generating surface gradients in chemical composition, mass density and residual stress.The most prominent post-processing methodologies for enhancing the strength of glass products rely on diffusive

Surface Hardness and Abrasion Threshold of Chemically Strengthened Soda-Lime Silicate Glasses After Steam Processing

“…Most prominently, thermal or chemical strengthening are widely employed to impose a surface compressive layer which counteracts tensile loading [9]. Thermal strengthening requires relatively thick glass sheet (or container walls) and rapid quenching of the surface of a hot glass product [13], for example to be used as solar covers, safety windows or in roof-top applications. Chemically strengthened glasses are produced by diffusive exchange of the mobile alkali ions (IOX) present in the precursor glass through immersion of the glass in a bath of molten salt.…”

Advancing the Mechanical Performance of Glasses: Perspectives and Challenges

“…For example, while higher packing density—such as achieved by slower cooling [ 48 ] or cooling under pressure [ 49 ] —would facilitate plastic deformation in principle, it was also found that rejuvenation by rapid quenching facilitates material deformation through structural compaction, leading to higher defect resistance. [ 8,50 ] Furthermore, additional p,T‐dependent reactions may occur, such as the tetrahedral‐to‐trigonal coordination transition of borate species. [ 51 ] In the case of borate‐containing glasses, such reactions may significantly reduce the stress threshold for shear deformation.…”

“…[3] As another example, roll-to-roll processing of ultrathin and flexible glass substrates has been made possible; [4,5] advanced dicing and postprocessing techniques have led to defect-free and, thus, strong edges to withstand bending loads. [6,7] Thermal tempering has been enabled for thin-walled glass products, [8] usable in glass-glass solar modules, flexible mirror substrates, quadruple-glazing, and lightweight glass containers. Optical fibers with enhanced bending resistance (both mechanical and in terms of optical loss) are used for fiber-to-the-X as well as short-haul light transmission techniques, or even suggested for integration as a functional component within textile structures.…”

Hardness and scratch resistance of chemically strengthened alkali‐borosilicate thin glass

“…Among them, B 2 O 3 is of particular importance, given its pivotal role for a wide variety of specialty glasses. 25 In this context, technologies for strengthening of thin borosilicate glasses, including thermal strengthening via liquid metal immersion, 26 as well as chemical strengthening, [27][28][29] have recently received renewed interest.…”