Tempered glass

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The items toughened safety glass and tempered glass overlap thematically. Help me to better differentiate or merge the articles (→  instructions ) . To do this, take part in the relevant redundancy discussion . Please remove this module only after the redundancy has been completely processed and do not forget to include the relevant entry on the redundancy discussion page{{ Done | 1 = ~~~~}}to mark. Kai Kemmann ( discussion ) - Improving instead of deleting : Encyclopedia is ancient Greek for "comprehensive" - 15:47, May 27, 2019 (CEST)


Tempered glass is a type of glass in which mechanical stresses are specifically generated in the material through heat treatment , thereby increasing the breaking strength against mechanical or thermal stress.

Glass panes that have been strongly tempered by thermal treatment break into many small fragments when damaged. These fragments are less sharp and dangerous than fragments of ordinary glass. Such tempered glass is used as safety glass and is usually referred to as single-pane safety glass (ESG) to distinguish it from bonded laminated safety glass (VSG) .

Less toughened glass is known as partially toughened glass , or TVG for short (regulated in DIN EN 1863-1). The cooling process takes place more slowly with this. This results in lower tension differences in the glass between the core and the surfaces. The flexural strength of 70 N / mm² lies between that of float glass 45 N / mm² (according to EN 572) and toughened safety glass 120 N / mm² (according to DIN EN 12150). With 100 K, TVG has a higher thermal shock resistance than float glass with approx. 40 K (according to EN 572). TVG is mainly used for the production of laminated safety glass. Due to the large-format fragments, LSG made of HSG has a higher residual load-bearing capacity, so that it can be used as overhead glazing and fall-proof glazing.

Manufacturing

The finished glass workpiece is heated in an oven and then quickly cooled. As a result of this quenching, the surface solidifies and the external dimensions of the component now only change comparatively little. However, the warmer core continues to contract even more, as the thermal expansion above the transformation point is significantly higher than below it. This creates a permanent field of tension in the component: a ball is pretensioned both radially and tangentially, a disc is under compressive stress on its surfaces, while in the center it is under tensile stress - a neutral fiber runs in between .

properties

Thanks to this frozen pre-tensioning, the tempered glass can compensate for significantly higher tensile loads than untreated glass. Since the compressive strength of glass clearly exceeds the tensile strength , this represents an overall improvement. However, a workpiece treated in this way can no longer be cut, ground or broken non-destructively - as is possible with untreated glass. In the event of glass breakage, the component breaks down into small crumbs.

use

Tempered glass is used wherever increased mechanical or safety requirements are placed on glass, for example: