Schott Robax vidros especiais vidros vidro para lareira vidro resistente ao fogo vidros para churrasqueira vidro cerâmica 14 4. The following technical information is generally valid for ROBAX®. Unless otherwise indicated, the data provided are guide figures. Values for which no generally applicable measurement method exists or alternatively which are not defined in a generally applicable manner (for example by means of a standard), are specified and explained.  approx. 2.6 g/cm3 (at 25 °C) E approx. 93 x 103 MPa (at 25 °C) The test is carried out in accordance with ASTM 1259-01. A tensile or compressive load is applied to a rod-shaped test piece to produce a change in length, the amount of which depends on the material and load. The modulus of elasticity describes the relationship between the tension and the material’s change in length. 4.1 General information 4.2 Mechanical properties 4.2.1 Density 4.2.2 Modulus of elasticity/ Young’s modulus 4. Technical properties – quality in numbers, information and facts In addition to an attractive appearance, ROBAX® is distinguished in particular by its “inner” values. Whether mechanical, thermal, chemical, or optical properties – the transparent glass ceramic meets even the highest requirements with a flourish. Schott Robax vidros especiais vidros vidro para lareira vidro resistente ao fogo vidros para churrasqueira vidro cerâmica 15 4. μ approx. 0.25 The test is carried out in accordance with ASTM 1259-01. A mechanical stress applied longitudinally produces both an increase in length and lateral contraction. As the length changes, so do the dimensions of the piece at right angles to the load. bB approx. 35 MPa The test is carried out in accordance with DIN EN 1288 T5, with the surface in its normal condition of use as encouraged in practice. Comments on impact resistance are only possible with knowledge of the specific application. Of particular importance here are application-specific standards as regards strength requirements. Nominal value on request. Indications of the strength of glass and glass ceramic must take into account the special properties of these materials. In the technical sense, glass and glass ceramic are “ideally elastic”, brittle materials which exhibit no tendency to flow. When they come into contact with materials of the same hardness, this causes surface damage in the form of fine nicks and cracks. When glass and glass ceramic are subjected to a mechanical load, the build-up of critical stress at the points of such nicks and cracks cannot be relieved by plastic flow, as is possible with such materials as metals. The consequence of this behavior is that the structurally based high strength of glass and glass ceramic (≥ 104 N/mm2) is irrelevant in practice. It is reduced by the effect of unavoidable surface defects (in the case of unprotected surfaces) to a practical value of approx. 20 to 200 N/mm2 bending strength – depending on the surface state and test conditions. The strength of glass and glass ceramic is therefore not a material constant (as for example its density), but is dependent on the following criteria: • finish condition of the panel (incl. edge finish, boreholes, etc.) • usage condition (type and distribution of surface defects) • time-related conditions or alternatively the duration of the effective load • surrounding conditions (corrosive substances, e.g. hydrofluoric acid) • the area subject to load as well as the thickness of the panel • the type of panel in installation The strength is also subject to a statistical distribution in accordance with the type and distribution of the surface defects. 4.2.3 Poisson’s ratio 4.2.4 Bending strength 4.2.5 Impact resistance 4.2.6 Comments on mechanical properties