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RESISTAN® Glossary

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Abbé Number The Abbé number is a measure of the optical dispersion (variation of refractive index with wavelength) of a transparent material in proportion to the refractive index. The Abbé number as well as the refractive index depend on the material itself and on the annealing conditions during the ceramization. Both characteristics are function of the wavelength and measured at discrete spectral lines. Acid Resistance Class The ceramic material surface is boiled for six hours in 20 % hydrochlorid and acid and the weight loss is determined in mg/100 cm2. The ceramic is then classified into following classes: S1 Acid resistant S2 Slight acid attack S3 Moderate acid attack S4 High acid attack The test is carried out in accordance with DIN 12116. Alkaline Resistance Class The ceramic material surface is exposed for three hours to a boiling aqueous solution comprising equal quantities by volume of sodium hydroxide (NaOH) and sodium carbonate (Na2CO3). The weight loss is determined and the alkali classes are grouped as follows: A 1 Slight alkali attack A 2 Moderate alkali attack A 3 High alkali attack The test is carried out in accordance with DIN 12116. AR - Anti Reflective Coating The anti-reflective coating is only available on flat panels. It prevents reflections from the surrounding area. If you should require additional information, please do not hesitate to contact us.

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[B]

Bending Strength The test is carried out in accordance with DIN EN 1288 T5, with the surface in its normal condition of use as intended in practice. The bending strength is not a material constant, it depends on: the size, thickness and geometry of the panel, the treatment and usage condition of the panel (incl. edges, surface, boreholes), the type and time-related conditions of the impact, the surrounding conditions (e. g. corrosive substances) and the kind of panel installation.

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Coefficient of Mean Linear Thermal Expansion The Coefficient of Mean Linear Thermal Expansion (CTE) describes the change in length or volume per unit in relation to change in temperature at a given constant pressure. (DIN ISO 7991)

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Dielectric constant ε The dielectric constant describes the relative increase in capacitance by introducing a polarizable dielectric into a condenser previously in vacuum. The test is carried out in accordance with DIN 53483. Dielectric loss tangent The dielectric loss tangent tan δ describes the ratio of practical performance to ideal loss-free performance, which is dependent on the type of material as well as on frequency and temperature. The test is carried out in accordance with DIN 53483.

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Heat Capacity The specific heat capacity describes the heat energy required to increase the temperature of a unit quantity of a substance by a certain temperature interval cp(20 – 100°C). Hydrolytic Resistance Class 2 g of ceramic grains are heated with 50 ml of water for one hour in a boiling water bath. The alkali (sodium, potassium) given off is titrated with hydrochloric acid (HCI). The classes are classified on the basis of the acid usage or alternatively alkali leached out: HGB 1 High resistance HGB 2 Resistance HGB 3 Medium resistance HGB 4 Low resistance HGB 5 Very low resistance The test is carried out in accordance with DIN ISO 719.

[I]

Infrared range The infrared spectrum is often subdivided into smaller sections in accordance with the application fields of a material. The IR spectrum of RESISTAN® is divided into the following bandwidths (DIN 5031, part 7): 1) IR-A: 780 nm - 1.4 μm 2) IR-B: 1.4 μm - 3.0 μm 3) IR-C: 3.0 μm - 5.0 μm IR - Infrared coating RESISTAN® IR is manufactured from flat RESISTAN® panels. The application of special oxydic, electrically conductive coatings to one side of the glass results in the infrared portion of the radiation and thus the thermal radiation being largely reflected back into the fire. If you should require additional information, please do not hesitate to contact us.

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Knoop Hardness The test is carried out in accordance with ISO 9385 determining the mechanical hardness of a material. It is quantified by measuring the indentation produced by a diamond tip which is pressed onto the surface of a material. The Knoop test is specially developed for materials such as glass and ceramics, as opposed to the Vickers hardness test, which is designed for metals.

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Modulus Of Elasticity 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 Example: Low modulus of elasticity: high deformation or deformation at low stress. High modulus of elasticity: low deformation or deformation at high stress only In comparison: Rubber has a modulus of elasticity of 0,05 kN/mm2, aluminium has 73 kN/mm2 and glass has 60–90 kN/mm2. Maximum Temperature Gradient (MTG) Resistance of a material to temperature variances between a defined hot zone and cold edge of room temperature, without cracking due to thermal stress. M - Mirror Coating The mirror coating is only available on flat panels. The coating reduces the visibility of the interior (of an oven for example) when an illuminant or a fire is switched off. When turned on the light or the fire can be seen clearly. If you should require additional information, please do not hesitate to contact us.

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Opaque Material A material that is opaque for a certain range of wavelengths (e.g. visible light) does not transmit light, or only a very small fraction of it. Instead, the light is either reflected, absorbed or scattered. Opacity is expressed by an interaction coefficient (also called absorption coefficient) kλ, which describes the rate at which photons are absorbed or scattered within a material. The interaction coefficient is constant at any given wavelength and may range between 0 and infinity. While a material with a value of 0 is transparent, higher values indicate that the material is becoming more opaque. Many dispersive materials (such as glass ceramics) appear white due to the effect of Mie scattering. This effect is a form of atmospheric scatter which can be easily observed when the diameter of the scattering particles (such as the crystallites present in the material) is approximately equal to the wavelength of incident light. Please also consider Translucent Material.

[P]

Poisson's Ratio 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. Porosity The porosity is a measure of the void spaces in a material. It is measured as a fraction between 0 and 1 or as a percentage between 0 and 100%. (ISO 9385)

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Refractive Index The value of the refractive index as well as the Abbé number depend on the material itself and on the annealing conditions during the ceramization. Both characteristics are function of the wavelength and measured at discrete spectral lines. Roughness (Ra/Rms) The roughness is a measure of the surface texture and describes the magnitude of vertical deviations from the plane surface. The two most commonly used methods for measuring roughness, are the arithmetic mean (Ra) and the quadratic mean (Rms or root mean square). In the one-dimensional form, for a number of data points N: the arithmetic mean the quadratic mean (Rms – root mean square)

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[T]

Thermal Shock Resistance (TSR) Resistance of the material to thermal shock when the hot material is quenched with cold water (room temperature), without cracking due to thermal stress. Temperature Time Load Capacity (TTLC) The temperature / time load capacity specifies the maximum permissible temperatures for load times of the material, below which no cracking should occur due to thermal stress. The temperature / time load data differ for uneven and even temperature distribution within the material. Translucent Material A translucent material transmits diffuse light, so that only a hazy image of the objects behind it can be seen. Translucency is dependent on the presence of particles and their diameter relative to the wavelength of incident light. Translucency is the opposite of opacity. The lower the interaction coefficient (expressing the opacity) of the material, the more translucent it is. When a material does not scatter any or very little of the transmitted light, it is called as transparent instead. Please also consider Opaque Material.

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