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The invention relates to a layer system for coating a substrate, to a substrate with such a layer system and to a method for producing a coated substrate.
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For improved thermal insulation in transparent panes, in particular glass panes in buildings or motor vehicles, so-called low-E layer systems are known which have a low emissivity of typically less than 0.05 in the infrared spectral range. For the low-E properties, one or two silver layers are arranged in a layer system, which can be combined with further, metallic or oxidic layers in the layer system for antireflection, as a diffusion blocker or adhesion promotion.
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Such low-E layer systems can be produced for example by means of magnetron systems or by cathode sputtering or sputtering. In general, such layer systems on flat, transparent substrates, such. As flat body, ribbons (flat glass, float glass) or glass panes or glass replacement materials, such as plastic applied.
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The
DE 196 04 699 C1 relates to a low-emissivity and high-transmission heat-insulating layer system in the visible spectral range provided for coating transparent substrates such as glass substrates and produced by cathode sputtering. This known layer system comprises at least four layers, namely at least one functional layer made of silver, an antireflection coating layer disposed between the substrate surface and the silver layer, another dielectric antireflection coating layer disposed above the silver layer, and one disposed between the silver layer and the antireflective coating layer Protective layer, a so-called sacrificial metal layer arranged. The sacrificial metal layer contains 0.05 to 10 wt .-% of at least one of the metals palladium (Pd), gold (Au), iridium (Ir), platinum (Pt) and rhodium (Rh) to increase the chemical resistance and hardness of the layer system , Also, below the silver layer may be arranged such a sacrificial metal protective layer. The silver layer itself consists of pure silver, the protective layers contain no silver.
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For producing curved, curved or curved glass panes, the planar, already coated glass bodies are thermally bent by heating to the glass softening temperature range in special glass bending ovens, the glass being generally un-prestressed. In particular, both cylindrical and spherical curvatures can be achieved with such bending ovens. Cylindrical bends can be made, for example, by bending over a bending mold. Spherical curvatures can be produced, for example, by means of a frame shape, wherein the frame shape can be lowered, for example, in the middle. With the known bending methods, it is in particular possible to simultaneously bend two or more disks lying one above the other. For example, for the production process for glass sheets bent in this way
A. Petzold, H. Marusch, B. Schramm; "The building material glass", 3rd edition, page 88, publishing house for building Berlin directed. Such curved or curved glass panes come z. B. in building facades, doorways, corner windows, furniture or motor vehicles or road mirrors for use.
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A problem with this subsequent bending of already coated with a layer system glass is the thermal stability or load capacity of the layer system, which is at the high temperatures in the range of glass softening temperature of typically 600 ° C to 680 ° C, for example 635 ° C to 640 ° C. not allowed to change its properties in an inadmissible way and may not replace it.
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From the
DE 35 43 178 A1 is a layer system for coating disks of mineral glass known with a first layer of an oxide, for example SnO
2 , a second layer of a metal, a third layer of silver or a silver alloy with at least 50 wt .-% silver, a fourth layer of the metal as the second layer and a fifth layer of the oxide of the first layer, so a structure with two metal protective layers around the silver layer. The silver layer can in this case as a pure silver layer or as a silver alloy with alloyed copper (Cu) with a maximum of 20 wt .-%, palladium (Pd) with a maximum of 30 wt .-% and platinum (Pt) carried out with a maximum of 20 wt .-% be. However, alloying the silver with the stated alloyed proportions of these metals causes the absorption of the layer system to drop. However, advantages can also be achieved, such as the healing of defects in the silver layer and an improvement in the optical and electrical properties. The material of the second and fourth layers is tantalum (Ta), tungsten (W), nickel (Ni) or iron (Fe) or an alloy containing at least 50% of one of these metals. The mineral glass pane coated with this known layer system is subsequently heated to the softening temperature of the mineral glass and shaped or bent into a respectively desired final shape. It is described that the layer system at the for this deformation required high temperatures of about 640 ° C is thermally stable so that the properties of the layers do not deteriorate and the layers do not peel off.
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In the
DE 35 03 851 A1 describes a highly transparent heat-insulating layer system for a transparent substrate, in particular a glass pane, with a layer sequence metal oxide-silver metal oxide, which is produced by sputtering. The silver is now mixed with at least one substance of high melting point, in particular tungsten (W), rhenium (Re), tantalum (Ta), osmium (Os), niobium (Nb), molybdenum (Mo) and / or iridium (Ir) with a Proportion up to 10 wt .-%. Tungsten (W) is preferably admixed in a concentration of 0.4 to 0.6% by weight. As a result, the formation of islands and droplets otherwise observed with pure silver layers and also subsequent tearing of the layer during application of further oxide layers can be avoided when applying the thin silver layer, whereby the light absorption can be influenced and the optical properties can be improved.
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However, the high proportion of 0.4 to 0.6% by weight of tungsten causes a deterioration of light absorption in the product after a bending process. These refractory metals added to the protective layer only lead to an insignificant increase in the chemical resistance and hardness of the entire layer system. However, the mode of action of the metals contained in the process of growth of the disc layer is largely unclarified. However, it is considered possible that noble metal nuclei are formed, and that due to the isomorphism of said noble metals to silver, the condensation of silver is favored in a sputtering process by the precious metals acting as metallic nuclei.
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The
DE 10 2006 014 796 B4 discloses a thermally highly loadable low-E-layer system for transparent substrates such as glass with a lower, optionally consisting of several sub-layers anti-reflective coating, a ZnO: Al existing layer, an adjoining functional layer of silver, a metallic blocking layer above the silver layer, one of multi-layer upper antireflective layer and optionally consisting of several sub-layers cover layer, wherein the layers are applied by sputtering in a vacuum. The top anti-reflection coating has a sub-layer of ZnO: metal oxide contained Al or ZnO ZnMeO
x or Metallmischoxidschichtfolge type ZnO: Al / ZnMeO
3 N
4 or Si
x O
y N
z, and between these two sub-layers arranged
x is a sub-layer of Si and their direct contact preventing 0.5 to 5 nm thick separation layer of a metal oxide or mixed metal oxide with cubic crystal lattice on.
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In H. Sankur and W. Gunning, J. Appl. Phys. 66 (1989) it is mentioned that the crystallization behavior in the production of a layer system can depend on the one hand on the temperature, on the other hand also on the layer thickness of the individual layers. It is shown that, for example, no crystallization can be detected below a critical layer thickness of 50 nm. This is true for oxidic layers as far as possible. By contrast, a metallic layer behaves differently in a heating process, in particular a silver layer (Ag layer).
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The morphological layer structure of a layer of metallic silver (Ag) is so unstable that in the presence of oxygen already comparatively small temperature increases are sufficient to trigger serious layer changes. These layer changes occur, in particular, in the temperature range from 200 ° C. to about 700 ° C., which is just relevant for subsequent thermal forming of a coated substrate. The layer changes are phenomenologically caused by a rounding of the respective layer particles. This process already takes place at silver layer thicknesses in the range of 10 nm. These findings emerge in particular K.-J. Hanszen, Journal of Physics, Volume 150, page 527 (1958) and P. Smith e. al. Thin Solid Films 45 (1977), page 159 , For different, silver-containing layer systems, it is also pointed out, among other things, the need to protect the silver layer.
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The object of the invention is to eliminate or at least alleviate the disadvantages of the prior art. In particular, it is intended to provide a layer system for coating substrates, in particular glass substrates, which is thermally stable and stable, in particular in the case of thermal deformation of the substrate, in particular glass, subsequent to the coating with the layer system. Furthermore, a substrate and a production method are to be specified.
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This object is solved by the features of the independent claims. Refinements and developments of the invention will become apparent in particular from the dependent claims.
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The layer system according to claim 1 is suitable and intended for coating a substrate and comprises at least one silver-alloy layer. The silver alloy layer comprises at least the following components:
- • at least 99.90 M% silver (Ag) and
- Maximum of 0.10 M-% of at least one alloying element (or alloy addition) titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni) and zinc (Zn) group of elements.
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In the method for producing a coated substrate according to claim 7, a layer system comprising at least one silver alloy layer is applied to the substrate, the at least one silver alloy layer comprising silver (Ag) and at least one alloying element consisting of the scandium (Sc), titanium (Ti ), Vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni) and zinc (Zn).
wherein in the at least one silver alloy layer, the proportion of the silver is set to at least 99.90 M% and the proportion of the at least one alloying element to a maximum of 0.10 M%.
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In another aspect of the invention, in a method according to claim 8 which is claimed or independently of claim 7, a coated substrate is prepared by applying to the substrate a layer system comprising at least one silver alloy layer, the silver and each alloying element for forming the silver alloy layer is ablated or detached from a source material and the substrate surface is supplied and wherein the source material has a proportion of silver of at least 99.90 M% and a proportion of at least one alloying element of not more than 0.10 M%, in particular a range of 0.01M% to 0.10M%.
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The removal or removal of silver and alloying element (s) from the source material takes place in particular in the form of atoms or ions or reactive compounds. Preferred coating methods are cathode sputtering, high rate sputtering or sputtering, in particular magnetic field assisted sputtering, of the source material, but also thermal evaporation of the source material or other PVD or CVD processes, which are generally carried out in vacuo.
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Synonymous with weight percent (wt .-%) here (more accurate) term mass percent (M%) is used, ie the proportion or content of the respective component based on the total mass of the total composition, ie 100 wt .-% or M % Has. The stated M% for the alloying elements refer to the totality of all the alloying elements present, ie one, if only one is present, and all the alloying elements taken together, if several alloying elements are added to the silver.
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The inventor has recognized that it is important for the thermal stability of the layer system not only to know which alloying elements have which influences in the layer system, but also exactly what quantities are required. The alloys known in the art have often been developed from the viewpoint of achieving high strength at room temperature. Accordingly, they contain various alloying additions in the wide range of at least 0.4% by weight up to 50% by weight.
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In order to obtain a different type of temperature influence and higher temperature resistance or heat resistance, the invention is based on the finding that other alloying additions and at the same time significantly lower contents of alloying additives are to be used than in the prior art.
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On the basis of this knowledge, the invention proceeds from the consideration that a thermally loadable layer system, in particular a low-E layer system, can be provided by merely changing the composition of the silver layer (Ag layer) of the low-E layer system. but the other layers can (but do not have to) remain unchanged. As a result, the layer system can be produced in a technologically simpler manner, and there are also cost advantages over conventional layer systems.
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The invention is further based on the surprising finding that the thermal stability can be improved by using a silver alloy layer or the source material with a silver concentration of at least 99.90% by mass and thus at most one additional alloying element in the silver alloy 0.10 M%.
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As the alloying element (s) alloyed with the silver, the silver alloy layer or the source material according to the invention comprises at least one of scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), Iron (Fe), cobalt (Co), nickel (Ni) and zinc (Zn) group of elements, ie elements with the atomic number 21 to 30 in the periodic table of the elements.
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These according to the invention for the first time the silver in one or for a silver layer of a layer system, preferably low-E layer system, alloyed elements have to silver only a limited miscibility.
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This limited miscibility and especially the special properties of the particular alloying additives chosen according to the invention, in combination with the specific concentrations of silver and alloying additions according to the invention, lead to a significantly higher temperature resistance of the silver layer. This is probably explained by the fact that the fine graining and heat resistance increases and reduces the tendency to adhere without substantially impairing the chemical properties or, in general, the sheet resistance.
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Synonymous with weight percent (wt .-%) is here and below the more precise term mass percent (M%) used, ie the proportion of the respective component based on the total mass of the total composition, which has 100 wt .-% or M% ,
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The content or content of the alloying element (s) in the silver alloy layer or the swelling material is preferably at least 0.01 M% and then preferably in a range of 0.01 M% to 0.09 M%.
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In particular, alloying elements such as Ni, Cr, Mn and Zn are suitable.
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In one variant, the silver alloy layer or the source material may have several, in particular two, alloying elements, for example Ni and Cr. Alloys of the abovementioned elements have also proven suitable. In particular, binary Ni-Cr alloys come into question. In the case of chromium-nickel alloys, those with a nickel content of about 50 M% or more have proved to be particularly advantageous.
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The thickness of the silver alloy layer can be selected substantially arbitrarily. A thickness of the silver alloy layer of 7 to 250 nm, preferably 9 to 15 nm, has proved to be particularly advantageous.
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In general, at least one above or below the silver alloy layer arranged or this upstream or downstream dielectric, in particular oxidic, layer is provided, in particular the silver alloy layer on both sides or on one side embedded in the dielectric layer. However, the silver alloy layer can also be applied directly to the substrate.
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The layer system is preferably a low-E layer system or has an emissivity of at most 0.05 with respect to infrared radiation.
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Due to its temperature resistance, the layer system provided by the invention is particularly suitable for planar flat glass panes, which can be thermally bent or curved in the desired manner after application of the layer system. In particular, both flat glass panes come into question, which must meet special technological requirements, as well as those which can be used in a conventional manner with tempering process.
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As already mentioned, the layer system can be applied to a substrate. Particularly suitable is the layer system for substrates such as glass or glass substitutes. The term glass substitute is understood to mean any substance which can be used as a substitute for glass, such as, for example, plastics or glass ceramics, etc. In particular, the layer system is suitable for flat glass panes.
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To produce curved or curved coated substrates, the substrate with a layer system can be heated to a temperature of, for example, 635.degree. To 640.degree. C. after application of the layer system and bent or shaped, without the effects of the layer system being significantly impaired. When using a glass substrate this can be heated to its softening temperature and accordingly, in particular according to the methods of the prior art, for example, from the cited reference
A. Petzold, H. Marusch, B. Schramm; "The building material glass", 3rd edition, page 88, publishing house for building Berlin , are known to be shaped. Furthermore, due to the thermal stability of the layer system, the substrate, in particular glass substrate, with the already applied layer system also annealed or heated to temperatures up to the vicinity of the softening temperature (so-called thermal annealing) for a predetermined period of time to reduce or increase stresses in the substrate material reduce.
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The invention will be described in more detail below with reference to exemplary embodiments. For a better understanding, the solution according to the invention is compared with a comparative example according to the prior art.
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First, the comparative example according to the prior art will be discussed in more detail. Subsequently, an explanation of the solution according to the invention follows in a first and further embodiments.
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Comparative Example (prior art):
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An industrial continuous coating machine was used, with which a Variety of substrate types, especially plan substrates and pipe substrates in the DC (DC) and / or in the AC (AC) operation can be coated. By means of magnetic field-assisted (reactive) sputtering and / or magnetron sputtering, the following low-E layer system, which corresponds to the prior art, was applied to 4 mm thick float glass panes:
Glass / SnO 2 (25 nm) / ZnO: Al (9 nm) / Ag (11.5 nm) / NiCr (3.5 nm) / Cr (3.5 nm) / ZnO: Al (5 nm) / SnO 2 (33 nm) / Si 3 N 4 (2 nm)
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In the above description of the layer system, the individual layers are separated by slashes, and thicknesses of the respective layers are respectively indicated behind the layer composition in parentheses in nanometers (nm). The letter abbreviations correspond to the names in the periodic table of the elements.
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The ZnO: Al layers were sputtered from a metallic ZnAl target with 2 wt% Al.
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The block layer disposed on the silver layer was sputtered with argon as a working gas of a metallic NiCr target consisting of 80% by weight of Ni and 20% by weight of Cr. The base layer and the top anti-reflection layer of tin oxide (SnO 2 ) is sputtered reactively from an Sn target in an Ar / O 2 working gas atmosphere. The topcoat or topcoat (Si 3 N 4 ) was reactively sputtered from an Si target with an Ar / N 2 working gas.
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The Ag target consisted of 99.97 wt .-% Ag based on the feed and thus 0.03% residual components.
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From the coated glass sheet having a length of 400 mm, a width of 200 mm and a thickness of 4 mm, samples required for carrying out bending tests were cut.
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The glass had the following oxide glass composition Na 2 O: 14% by weight; MgO: 4.0% by weight; Al 2 O 3 : 0.1% by weight; SiO 2 : 72.5% by weight; K 2 O: 0.016 wt%; CaO: 9.0% by weight.
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Subsequently, in order to bend the coated glass pane, one of the samples was placed in a tunnel oven. The tunnel kiln was heated at a rate of 2 ° C / min by means of an electrotherm oven heater to temperatures in the range of 635 to 640 ° C. It was then cooled at oven speed and the samples were removed after cooling from the tunnel kiln. The process was completed when the layer in the tensile stress region from the plane sample, a cylindrical shape was created.
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All of the three samples prepared in the comparative example showed line-like defects across the sample in the region of highest tensile stresses. In this area, the stray light was measured at 1% with a Gardner device.
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In the following, embodiments according to the invention will be described in more detail.
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First embodiment according to the invention:
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The first embodiment according to the invention differs from the comparative example only in the Ag target used, so that otherwise the same technology and the same process parameters were used.
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The Ag quality of the Ag target mentioned in the comparative example according to the invention was admixed with 0.07% by weight of Ni, so that the target had 99.90% by weight of Ag at 0.03% of other residual constituents. The layer formation took place with the same thicknesses as in the comparative example.
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The process control in the tunnel kiln was the same. When heating up to 635-640 ° C with the electrothermic heater, the incipient sinking of the two edges of the sample indicates the softening point of the glass.
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After cooling, the samples were removed from the oven and the region of highest tensile stresses in three samples was examined for the line-type defects across the sample. The typical defects, especially line-like defects, were not observed in the samples of the embodiment. In the region of highest tensile stresses, the scattered light was measured to be 0.4% as above in the comparative example with a Gardner apparatus. This value is significantly below the value in the comparative example, which shows in particular that the layer system which has been formed or produced according to the invention is thermally substantially stronger and more stable than in the prior art.
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Further embodiments:
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Comparable improvements of the thermal stability result in other embodiments also at other values of the Ni concentration in the target in a range between 0.1 M% and 0.09 to 0.10 M% and also when using other alloying elements in the target namely scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co) or zinc (Zn) or a binary alloy of two of these materials and or one of these materials with nickel (Ni), in particular a binary NiCr alloy with a Ni content of at least 50 wt .-%.
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The alloying elements added to the silver in compliance with the amounts according to the invention and specified in more detail above advantageously result in increased fineness and heat resistance and reduced tendency to adhere without the chemical properties or the surface resistance being significantly impaired. Here, the effect of the added elements may be different. It should be noted that the addition of the at least one alloying element is usually the more effective, the lower the proportion of the alloying elements added or, and the better each of the desired properties mentioned above are achieved.
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QUOTES INCLUDE IN THE DESCRIPTION
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This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.
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Cited patent literature
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- DE 19604699 C1 [0004]
- DE 3543178 A1 [0007]
- DE 3503851 A1 [0008]
- DE 102006014796 B4 [0010]
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Cited non-patent literature
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- A. Petzold, H. Marusch, B. Schramm; "The Building Material Glass", 3rd edition, page 88, Verlag für Bauwesen Berlin [0005]
- H. Sankur and W. Gunning, J. Appl. Phys. 66 (1989) [0011]
- K.-J. Hanszen, Zeitschrift für Physik, volume 150, page 527 (1958) [0012]
- P. Smith e. al. Thin Solid Films 45 (1977), page 159 [0012]
- A. Petzold, H. Marusch, B. Schramm; "The Building Material Glass", 3rd edition, page 88, Verlag für Bauwesen Berlin [0036]