Confocal detection of Rayleigh scattering for residual stress measurement in chemically tempered glass

Hödemann, Siim; Möls, P.; Kiisk, V.; Murata, Takashi; Saar, Rando; Kikas, J.

doi:10.1063/1.4938200

Cited by 11 publications

(8 citation statements)

References 19 publications

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“…The validity of the measured stress profiles was tested by the criteria of stress equilibrium (difference in the areas of compressive and tensile zones) and by comparison with Na + ion concentration profiles. Our results are compared to analogous studies by Varshneya et al, Jannotti et al and Inaba et al…”

Section: Introductionsupporting

confidence: 73%

Measurement of stress build‐up of ion exchange strengthened lithium aluminosilicate glass

Hödemann

Valdmann

Paemurru³

et al. 2019

J Am Ceram Soc

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A recently developed nondestructive method was used to investigate the stress buildup in chemically strengthened lithium aluminosilicate glass. We utilized an updated version of the gradient scattered light method, which now enables more precise determination of the depth coordinates, recovering a more detailed stress profile around the knee. The main motivation of the work was to characterize and optimize the development of the knee-shaped breaking point in stress profile in lithium aluminosilicate glass prepared by the Saunders-Kubichan method of one-step strengthening in a mixture of KNO 3 +NaNO 3 molten salt bath. In the industry, a two-step process is still commonly used to build such a stress profile; the one-step strengthening will simplify the process as well as save the cost. Compared to previous studies, which used a destructive method based on transmitted light photoelasticity, we found that in the samples ion exchanged for 24 hours, the knee-shaped breaking points were situated two times deeper whereas the case depths were 28% shallower. The measured stress profiles were validated by stress equilibrium and by comparison to Na + ion concentration profiles. K E Y W O R D S glass, ion exchange, polarization, refractive index, scattering 2408 | HÖDEMANN Et Al. How to cite this article: Hödemann S, Valdmann A, Paemurru M, et al. Measurement of stress build-up of ion exchange strengthened lithium aluminosilicate glass.

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Section: Introductionsupporting

confidence: 73%

Measurement of stress build‐up of ion exchange strengthened lithium aluminosilicate glass

Hödemann

Valdmann

Paemurru³

et al. 2019

J Am Ceram Soc

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“…Figure 4 (a) shows a comparison between the optical retardation d c y ð Þ along the curved ray path in depth coordinates (simulated using Eq. (21)) and the optical retardation d s y ð Þ (simulated directly from fully known r y ð Þ using Eq. (12)).…”

Section: Numerical Experiments Simulation Conditionsmentioning

confidence: 99%

“…Applying transmission photoelasticity to measure the stress profile can only be possible if the sample is prepared as described or cut. Automatic transmission polariscope AP-07 [20] (GlasStress Ltd.) that is equipped with magnification objective can also be used [21] instead of a manually operated polarization microscope.…”

Section: Introductionmentioning

confidence: 99%

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Gradient scattered light method for non-destructive stress profile determination in chemically strengthened glass

et al. 2016

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A new non-destructive gradient scattered light method is presented for micronscale stress profile measurement in chemically strengthened (chemically tempered, ion exchanged) glass. Direct non-destructive stress measurement in the surface layer (\100 lm) of chemically strengthened glass is reported for the first time. This is accomplished by passing a narrow laser beam through the surface layer of the glass at a considerably large incidence angle of 81.9°. The theory of gradient scattered light method is based on the ray tracing of ordinary and extraordinary rays in chemically strengthened glass and calculating the optical retardation distribution along the curved ray path. The experimental approach relies on recording the scattered light intensity and calculating the optical retardation distribution from it. The stress profile is measured in a chemically strengthened (8 h at 480°C in a salt mixture of 80 mol% KNO 3 and 20 mol% NaNO 3 ) lithium aluminosilicate glass plate to illustrate the capability of the method. Measured surface compressive stress was -1053 MPa and case depth 365 lm. Method is validated with transmission photoelasticity. The method could also be used for stress profile measurement in all transparent flat materials (such as very thin thermally tempered glass slabs or polymers). Additional new applications could be: (1) enhanced version of Bradshaw's surface layer etching method for stress profile measurement in case of ultra-thin case depths \20 lm;(2) micron-scale non-destructive tomography of layered polymeric gradient-refractive-index materials. The experimental procedure is developed to the level of full automation and the measurement time is less than 10 s.

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“…Conventionally, these two values are obtained from a depth profiling of stress via the photoelastic effect 18 ; e.g., stress evaluation devices based on both the photoelastic effect and the waveguide effect have been commercialized and used as a standard technique. Additionally, methods using both the photoelastic effect and light scattering have been recently proposed: Using these methods, Inaba et al succeeded in evaluating the stress in two-step ion-exchanged glass 5 , and Hödemann et al demonstrated stress detection with high spatial resolution using confocal microscopy 19 .…”

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confidence: 99%

A novel method for stress evaluation in chemically strengthened glass based on micro-Raman spectroscopy

et al. 2020

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Chemically strengthened glass is widely used for screen protection in mobile devices, and its strengthening processes and application fields have rapidly diversified. The origin of the strength is residual compressive stress induced by ion exchange, and the stress evaluation has been performed via the photoelastic effect. However, for a deep understanding of the nature of the strength and development of stronger glasses, we need a method directly connected to atomic-scale glass structures. Here, we propose a method based on the "stuffing" effect, where we can determine the residual stress non-contactively and nondestructively with a high spatial resolution using Boson, D 1 , D 2 , and A 1 peaks in micro-Raman spectra. Finally, we show a plausible depth dependence of the residual stress.

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Confocal detection of Rayleigh scattering for residual stress measurement in chemically tempered glass

Cited by 11 publications

References 19 publications

Measurement of stress build‐up of ion exchange strengthened lithium aluminosilicate glass

Measurement of stress build‐up of ion exchange strengthened lithium aluminosilicate glass

Gradient scattered light method for non-destructive stress profile determination in chemically strengthened glass

A novel method for stress evaluation in chemically strengthened glass based on micro-Raman spectroscopy

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