Papers by Keyword: Soda-Lime Glass

Abstract: This paper indicates the experiments of YAG laser cutting soda-lime glass with controlled fracture. The qualities of glass obtained by laser cutting and mechanical cutting are compared. The impact of laser power, scanning speed and spot size on the cutting quality is studied and the optimum laser parameters are given. Finally the experiments of laser cutting two-layer glasses, glass tube and laser cutting in curve paths are carried out. The results show that good cutting quality of glass can be acquired by YAG laser cutting.

Abstract: In laser cutting of glass with controlled fracture, thermal stress induces a fracture and the material is cleaved along the cutting path by fracture propagation. Compared with CO2 laser, YAG laser has many advantages in cutting glass with controlled fracture. As a volumetric heat source, YAG laser can penetrate through the glass. Therefore, the temperature distribution is uniform across the thickness of the glass and the fracture propagates from the top and bottom surface to the middle so that better cutting quality can be acquired and multi-layer glasses can be cut simultaneously. In this paper, a 1064nm YAG laser is applied to cut two-layer and four-layer glasses. Fracture propagation mechanism is studied by examining the temperature and stress fields using finite element software ANSYS11.0. Good cutting qualities of fracture surfaces for all the layer glasses are acquired and the cutting efficiency is greatly improved by this technique as well. Additionally, due to smaller laser spot size the glasses that are closer to the focal point have higher laser power density inside glass, which may lead to ablation and evaporation phenomenon. But lower laser power density is not enough for fracture initiation and expansion. Therefore, it’s important to find a proper laser power for all the layer glasses. Small tensile stresses on the top and bottom surfaces will make the material separate from up and down to middle, whereas the compressive stresses in the middle ensure stable fracture propagation. Moreover, the stable fracture propagation always lags behind the laser beam spot. High tensile stresses are distributed throughout the thickness of the glass in the leading and trailing edges, which leads to unstable fracture extension in the leading and trailing edges.

Abstract: MgO thin film was deposited on soda lime glass substrate by sol-gel process. MgO thin film with the (200) preferred orientation were prepared by heat-treated at 300~500°C for 10 min. The crystallization, microstructure and electrical properties with various parameters of MgO thin films were investigated. Consequently, it was shows that the (200) preferred orientation of MgO thin film could be obtained as the heating temperature was increased. At heating temperature of 500°C, MgO thin film was composed of columnar crystals with a size of 120 nm. The dielectric constant of the (200) preferred orientation of MgO thin film at 1 kHz without the electric field was 7.2, with a dissipation factor of 4%. When the electric field was increased, the dielectric constant approaches to 7.9 with the dissipation factor of 2.1%. The refractive index of MgO thin film depended on the film thickness. The refractive index of 250 nm thickness was 1.70.

Abstract: In the present work we discuss the self-affine properties of the fracture surfaces of sodalime glass obtained under quasi-static conditions. The fracture surfaces are generated using a threepoint bending system in normal room conditions and under high humidity conditions. The surfaces were recorded both by Scanning Electron Microscopy and Atomic Force Microscopy, and their selfaffine properties are characterized using the Variable Bandwidth method. For both conditions it is observed that the major part of the fracture surface is occupied by the mirror zone. On the other hand, the self-affine analysis reveals that for both conditions the roughness exponent has values centred at around 0.58 with moderate dispersion, in agreement with previous results. Our findings support the hypothesis of the existence of a characteristic roughness exponent for quasi-static fracture with a value that is significantly lower than the value of 0.8 reported for rapid fracture conditions.

Abstract: A direct measurement of the crack-driving stress has been attempted by applying a nanoindentation-combined, stress-probing technique to the expected crack routes ahead of a Vickers impression. The nanoindentation curves close to the remnant indent were compared to those of an unstressed bare sample and were interpreted into quantitative stress values. In detail, from the difference of two stress distributions measured from uncracked and cracked indentation corners, the driving stress for the radial cracking was estimated; a rapid decaying response with a distance to the Vickers indent center with the peak value 406.7MPa. The fracture toughness of soda-lime glass, estimated by taking into account the results measured in this study was 0.74 ± 0.15 2 / 1 m MPa × and was comparable with that of the literature.