<p>Experimental results of a complex study of the mechanical properties of technical and quartz glass at local static loads are presented. The SEVNB method adapted for glass specimens is shown to get accurate and reliable results verified by comparing them with the literature data. The damaging and fracture resistance characteristics were determined in Rockwell experiments of scratching the specimen surface to its edge chipping. Fractographic analysis of the specimen edge zones revealed the mechanisms of their local fracture. The specimen edge was mostly damaged with the occurrence of fully-formed ‘shell-like’ chip scars on its side, with the areas of fracture crack extension having different origins and appearances. Such patterns of edge chipping present traces of propagation of asymmetric Hertzian cone cracks, distorted by the close free edge location. In contrast, low indentation loads mostly resulted in smaller local fractures, characterized by an open chip scar surface, a network of randomly directed and branched secondary cracks, and small mirror zone dimensions. Such tests demonstrated the differences in initial defect levels in some points of glass specimen edges. Experimental data are proposed to be represented as damaging diagrams with characteristic ranges of possible glass edge damages for practical laboratory and production use. Such presentation of chipping results can serve for rapid glass damaging analysis and become an additional tool for determining the mechanical properties of materials. The hardness of glasses on Rockwell scratching and Vickers indentation was calculated, and the divergence of those values was demonstrated. A comparison of scratching hardness results with known literature data shows that they are tentative estimates and would require further investigations.</p>

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Mechanical Characteristics of Technical and Quartz Glass at Local Static Loads

  • V. V. Khvorostyanyi

摘要

Experimental results of a complex study of the mechanical properties of technical and quartz glass at local static loads are presented. The SEVNB method adapted for glass specimens is shown to get accurate and reliable results verified by comparing them with the literature data. The damaging and fracture resistance characteristics were determined in Rockwell experiments of scratching the specimen surface to its edge chipping. Fractographic analysis of the specimen edge zones revealed the mechanisms of their local fracture. The specimen edge was mostly damaged with the occurrence of fully-formed ‘shell-like’ chip scars on its side, with the areas of fracture crack extension having different origins and appearances. Such patterns of edge chipping present traces of propagation of asymmetric Hertzian cone cracks, distorted by the close free edge location. In contrast, low indentation loads mostly resulted in smaller local fractures, characterized by an open chip scar surface, a network of randomly directed and branched secondary cracks, and small mirror zone dimensions. Such tests demonstrated the differences in initial defect levels in some points of glass specimen edges. Experimental data are proposed to be represented as damaging diagrams with characteristic ranges of possible glass edge damages for practical laboratory and production use. Such presentation of chipping results can serve for rapid glass damaging analysis and become an additional tool for determining the mechanical properties of materials. The hardness of glasses on Rockwell scratching and Vickers indentation was calculated, and the divergence of those values was demonstrated. A comparison of scratching hardness results with known literature data shows that they are tentative estimates and would require further investigations.