INSULATING GLAZED COMPRISING LAYERS OF ITO AND NIOBIUM NITRIDE

Abstract

A transparent glazing article, comprising at least one glass substrate equipped, on at least one of its faces, with a coating consisting of a stack of thin layers, the coating comprising the following sequence of layers, with reference to the surface of the substrate: - a first layer comprising niobium nitride, - a layer comprising a transparent conductive oxide, - a second layer comprising niobium nitride, wherein the first and second layers comprising niobium nitride are in direct contact with the layer comprising a transparent conductive oxide.

Description

INSULATING GLAZED COMPRISING LAYERS OF ITO AND NIOBIUM NITRIDE FIELD OF INVENTION The invention relates to the type of insulating glazing known as solar control glazing, which consists of stacks of thin layers, at least one of which is functional, meaning it acts on solar and / or thermal radiation primarily by reflecting and / or absorbing near-infrared (solar) or far-infrared (thermal) radiation. The present invention relates more particularly to glazing comprising one or more layers, and especially to glazing intended primarily for thermal insulation in buildings. BACKGROUND OF THE INVENTION For the purposes of this patent application, one or more “functional” or “active” layers are understood to be one or more layers of the stack that provide it with most of its thermal properties. More often than not, the thin-film stacks used to glazing provide enhanced solar control properties primarily through the intrinsic properties of one or more active layers. A functional layer acts on the flow of solar radiation passing through the glazing, in contrast to other layers, which are generally made of dielectric material and whose function is to chemically or mechanically protect the functional layer or to adjust the color. Such glazing equipped with stacks of thin layers acts on the incident solar radiation, either essentially by absorption of the incident radiation by the functional layer or essentially by reflection by this same layer. These are grouped under the designation "solar control glazing". They are sold and used primarily to protect homes from solar radiation and prevent overheating; in technical terms, these glazing products are classified as anti-solar glazing. Alternatively, they are used to thermally insulate homes and prevent heat loss; in this case, they are classified as insulating glazing. By anti-solar, what is meant in the context of the present invention is the ability of the glazing to limit the flow of radiation, in particular infrared solar radiation (IRS), that passes through it from the outside to the inside of the dwelling or passenger compartment. To measure the thermal insulation properties of glazing, the solar factor (indicated as SF) is used in the field. As is known, the solar g-factor is equal to the ratio of the energy passing through the glazing (i.e., entering the building) to the incident solar energy. More specifically, it corresponds to the sum of the flux transmitted directly through the glazing and the flux absorbed by the glazing (including any stacks of layers present on one of its surfaces) and then potentially re-emitted into the building. Furthermore, to estimate the ability of a glazing to reflect and / or absorb infrared solar radiation (between 1 micron and 30 microns) while allowing radiation in the visible domain (between 380 and 780 nm) to pass through, the Túg ratio, which is often called field selectivity and where Tl is the light transmittance, is commonly considered. pQpfrnn / zznz / E / YiAi To achieve good thermal insulation properties, the functional layer must first have low resistivity. However, this property also results in greater light absorption, which tends to significantly decrease the light transmittance of the glazing. The objective of the present invention is, firstly, to provide glazing equipped with a glazing unit that offers a good compromise between its light transmittance and its thermal insulation properties. In general, all the light-related characteristics presented in this description, in particular the light transmittance Tl and the light reflectance Rl, but also the g factor, are obtained in accordance with the principles and methods described in the standard NF EN 410 (2011), which relates to the determination of the light and energy characteristics of glazing used in building glass. Ideally, the glazing should have a substantially neutral color in both transmission and reflection, whether from the face of the glazing on which the stack is deposited (inner side) or from the opposite face (outer side). The most efficient glazing units currently available incorporate at least one metallic layer made of silver, which essentially functions by reflecting most of the incident infrared (IR) radiation. Therefore, these units are primarily used as low-emissivity (or low-e) glazing for thermally insulated buildings. These layers, however, are highly sensitive to moisture and oxidation. Consequently, they are used exclusively in double-glazed units, on surface 2 or 3, for moisture protection. Therefore, it is not possible to deposit such layers on single-pane glazing (also known as monolithic glass). The glazing units according to the invention do not comprise silver-based layers, or even gold- or platinum-based layers, or if they do, they are present in very negligible quantities and, in particular, as unavoidable impurities. Similarly, the functional layers, or even the stacks, of the glazing articles according to the invention are free of nickel or copper. Batteries with low emissivity or anti-solar properties are also known, but they are based on functional layers made of transparent conductive oxides (TGOs) such as mixed indium tin oxide, for example, the batteries described in application US2009320824. However, to obtain coatings with a solar factor significantly lower than 50%, it is necessary to deposit layers with thicknesses of at least 100 nm. Therefore, deposition of these layers using magnetron sputtering techniques is time-consuming and expensive. Other metallic coatings with an anti-solar function have also been reported in the field, comprising functional layers of the metallic Nb or niobium nitride (NbN) type, as described, for example, in patent application WO01 / 21540 or patent application WO2009 / 112759. Within the niobium and, in particular, niobium nitride coatings, solar radiation is predominantly and non-selectively absorbed by the functional layer, while IR radiation (i.e., radiation with a wavelength between approximately 780 nm and 2500 nm) and visible radiation (with a wavelength between approximately 380 nm and 780 nm) are absorbed indiscriminately by the active layer. The use of metallic niobium results in glazing units equipped with such coatings having higher internal reflectance values. rocfrnn / zznz / E / YiAi Besides its solar protection properties, in the construction sector, and indeed in the automotive field, it is also important, among other things, that the glazing appear almost colorless in terms of transmission and internal reflection to the occupant of the dwelling or passenger compartment. To achieve such neutrality, the glazing must be almost colorless; that is, not only must the a* and b* values ​​in the L, a*, b* space be low for both transmission and internal reflection—typically less than or equal to 10, or ideally less than 5 in absolute value—but also the internal light reflectance must be as low as possible. Generally, in these glazing systems, it is necessary to limit the interior reflection as much as possible (i.e., the reflection of light from the inner surface of the glazing placed in the building or passenger compartment, i.e., from the face of the glazing on which the stack of layers is deposited). To simultaneously solve these problems, it is necessary to provide glazing items with suitable luminous characteristics. In particular, the problem described above has been solved, according to the invention, by the development of glazing articles that meet most, and very often all, of the following criteria: - the light transmittance is greater than or equal to 15%, - the Runt light reflectance on the stack side (inner side) is less than or equal to 20%, or even less than or equal to 15%, or even less than 10%, - the parameters a* and b* in the transmission, in the L color space, a*, b*, are less than 10 and preferably less than 5. - Preferably, the parameters a* and b* in internal reflection are less than 10 and preferably less than 5, in the L, a*, b* color space. According to the invention, the parameters L, a* and b* are measured according to CIELAB criteria, at an angle of 10° and under the D65 illuminant. The battery side refers to the face of the glazing on which the battery is placed. The glass side refers to the face of the glazing opposite the battery side, which is not covered. In the context of the present invention, the terms "outer face" (or "external") and "inner face" (or "internal") refer to the position of the glazing when it is installed in the building or vehicle for which it is intended. Furthermore, the glazing and glazed articles according to the invention have thermal insulation properties in accordance with those required in the field, and in particular a solar g-factor close to 50% and preferably less than 50%, or even less than 45% or even less than 40% in certain configurations. BRIEF DESCRIPTION OF THE INVENTION The objective of the present invention is to provide a glazing article that allows the technical problems described above to be solved. More precisely, the present invention relates to a transparent glazing article, comprising at least one glass substrate equipped, on at least one of its faces, with a coating consisting of a stack of thin layers, the coating comprising the following sequence of layers, with reference to the surface of the substrate: - a first layer comprising niobium nitride, - a layer comprising a transparent conductive oxide, in particular an indium-tin oxide, - a second layer comprising niobium nitride, wherein the first and second layers comprising niobium nitride are in direct contact with the layer comprising a transparent conductive oxide. According to particular and preferred embodiments of the present invention, which, when appropriate, may be combined with each other: - The layer comprising a transparent conductive oxide has a thickness between 5 nm and 400 nm, preferably between 10 and 200 nm, in particular between 15 and 100 nm, and for example between 20 and 70 nm. - The first layer comprising niobium nitride has a thickness between 1 and 50 nm, and more preferably between 2 and 30 nm. - The second layer comprising niobium nitride has a thickness between 1 and 50 nm, and more preferably between 2 and 20 nm. - The transparent conductive oxide is chosen from indium-tin oxides (ITO), zinc-aluminum oxides (AZO), antimony-tin oxides (ATO) and indium-zinc oxides (IZO), and preferably from indium-tin oxides (ITO). - The transparent conductive oxide is chosen from a tin oxide that is doped to make it conductive, preferably doped with an element chosen preferably from F, Sb, Al and Ag, and most preferably doped with fluorine or antimony. - The layer comprising a transparent conductive oxide is thicker than the first and second layers comprising niobium nitride. - The battery does not comprise functional layers based on Ag, Au, Pt, Cu, Ni or stainless steel. - At least one layer of a dielectric material, preferably comprising silicon nitride or silicon nitride-based material, is placed over the succession of layers, with reference to the substrate surface. - At least one layer of a dielectric material, preferably comprising silicon nitride or silicon nitride-based material, is placed beneath the succession of layers, with reference to the substrate surface. - The dielectric material is chosen from nitrides, in particular silicon nitride and aluminum nitride and mixtures thereof, or oxides, in particular silicon oxide, titanium oxide, tin oxide, zinc oxide and mixtures thereof. - A layer comprising silicon nitride is placed above and / or below the succession of layers. - The stack comprises or consists of the following layers, each layer being in direct contact with the next: SiNx / NbNx / TCO / NbNx / SiNx, wherein SiNx designates layers comprising silicon nitride, NbNx designates layers comprising niobium nitride, and TOO designates layers comprising a transparent conductive oxide, racfrnn / zznz / E / YiAi, the transparent conductive oxide being preferably an indium tin oxide. As indicated above, the formulation SiNx is a general formulation used to designate a layer comprising silicon nitride or silicon nitride-based, the value of x being, of course, liable to vary substantially from the stoichiometric value (4 / 3) corresponding to a Si3N4 formulation, for example, due to the presence of dopants such as aluminum or even to particular deposition conditions leading to super- or sub-stoichiometry. - At least one layer comprising a metal oxide is present between the surface of the glazing substrate and said succession of layers; the metal oxide is preferably chosen from silicon oxide and titanium oxide. - At least one layer comprising a metal oxide is present over the succession of layers, the metal oxide being preferably chosen from silicon oxide, titanium oxide, zirconium oxide or a mixture of these oxides. - The article is tempered and / or thermally bent. The invention also relates to a curtain-wall panel of the type called spandrel glass, which incorporates at least one article such as the one described above. Throughout the description, unless otherwise stated, thicknesses are physical thicknesses. In the layers according to the invention comprising silicon nitride, the silicon nitride preferably represents at least 50% by weight of the layers, based on a Si3N4 formulation, and preferably more than 80% or even more than 90% of the layers, based on the Si3N4 formulation. More preferably, the layers consist essentially of silicon nitride, but may also comprise aluminum. Aluminum is well known to be used in proportions of up to 10% or more in silicon targets used for magnetron sputtering (magnetic field-assisted sputtering) of silicon-containing layers, and in particular silicon nitride-based layers. In the layers according to the invention comprising niobium nitride, the niobium nitride NbNx preferably represents at least 50% by weight of the layers, and more preferably more than 80% or even more than 90% of the layers. In the NbNx formulation according to the invention, x may vary, for example, between 0 and 1, preferably between 0 and 0.9, and, for example, between 0.3 and 0.7. The formulation of the layers, and in particular the value of x, can be conventionally obtained by X-ray photoelectron spectrometry (XPS), using techniques well known in the field of materials. According to a preferred embodiment of the invention, the layers preferably consist essentially of niobium nitride, or in fact consist of niobium nitride, apart from unavoidable impurities. The layer comprising niobium nitride may further comprise a small amount of oxygen, for example, such that the atomic ratio O / Nb is less than 0.2, and preferably less than 0.1. However, according to a preferred embodiment, the layers comprising niobium nitride do not comprise oxygen, other than the oxygen found in unavoidable impurities. In a layer according to the invention comprising an indium tin oxide (ITO), the ITO preferably represents more than 50% by weight of the layer, and preferably more than 80% or even more than 90% of the layer. According to a preferred embodiment of the invention, the layers preferably consist of ITO or in fact consist of ITO, apart from unavoidable impurities. In the context of the present invention, a transparent conductive oxide (or TCO to use the acronym commonly used in the field) is understood to mean any layer known to have sufficient conductivity to allow its use as a functional anti-solar or low-emissivity layer that allows the reflection and / or absorption of infrared, and in particular solar infrared (between 800 and 2500 nm). Indium tin oxide (or even tin-doped indium oxide or ITO) also means a mixed oxide or mixture obtained from the oxides of indium(III) (InzOs) and tin(IV) (SnOz), preferably in mass proportions of between 70 and 95% for the former oxide and between 5 and 20% for the latter. A typical mass ratio is approximately 90% by mass of InzOs to approximately 10% by mass of SnOz. The coatings according to the invention are conventionally deposited using deposition techniques such as vacuum magnetron sputtering of a cathode of the material or a precursor of the material to be deposited; this technique is often called field magnetron sputtering. Currently, this technique is conventionally used, particularly when the coating to be deposited consists of a more complex stack of successive layers with thicknesses of a few nanometers or tens of nanometers. The present invention also relates to a curtain-wall panel of the type called spandrel glass that incorporates at least one glazing as described above, or to a side window, rear window or roof of a car or other vehicle comprising or incorporating the glazing. According to the invention, the functional layers according to the invention allow obtaining a relatively high value of the light transmittance of the substrate, which allows undisturbed viewing from the inside out, while preserving a remarkable thermal insulation effect. The terms “bottom layer” and “top layer” refer, in this description, to the respective positions of the layers with respect to the functional layers of the stack, the stack being supported by the glass substrate used as a reference. In particular, the bottom layer is generally the layer in contact with the glass substrate and the top layer is the outermost layer of the stack, this layer oriented in the opposite direction to the substrate. Although the application to which the invention is most particularly directed is architectural glazing, it will be understood that other applications are conceivable, in particular automotive glazing (apart from windshields, where very high light transmittance is required) such as side windows, sunroofs or rear windows. The invention and its advantages are described in more detail below by means of the following non-limiting examples, which are in accordance with the invention and for comparison. In all examples and descriptions, the thicknesses given are physical. All substrates are made of 6 mm thick transparent glass of the Planilux® type sold by Saint-Gobain Glass France. All layers are deposited in a known way by magnetron sputtering. As is well known, the different successive layers are deposited in successive compartments of the sputtering device, each compartment being equipped with a specific metallic target of Si or Nb and chosen for the deposition of a specific stack layer. More precisely, silicon nitride layers are deposited in a first compartment of the device using a metallic silicon target (doped with 8 wt% aluminum) in a reactive atmosphere containing nitrogen (40% Ar and 60% N2). The silicon nitride layers, designated Si3N4 for convenience, therefore contain a small amount of aluminum. These layers are subsequently designated by the conventional general formulation ShN4, although the deposited layer does not necessarily have this assumed stoichiometry. NbNx layers are obtained by spraying a metal-niobium target in an atmosphere containing a mixture of nitrogen and argon, under the conditions described in publication WO01 / 21540 or even in publication WO2009 / 112759. ITO layers are deposited by spraying a ceramic oxide target comprising tin and indium in mass proportions of 90 / 10 in an atmosphere containing a mixture of oxygen and argon using techniques well known in the art. DETAILED DESCRIPTION OF THE INVENTION Examples 1 to 4 according to the invention: In all of Examples 1 to 4 that follow, the glazing substrate was successively coated with a stack of layers comprising an ITO layer flanked by niobium nitride and Si3N4 layers. In these examples, the stack therefore consists of an ITO layer encapsulated with two niobium nitride layers and two silicon nitride layers, according to the following sequence: Si3N4 / NbNx / ITO / NbNx / Si3N4. Different piles were synthesized to adjust the solar factor and light transmittance to obtain different possible configurations desired in the construction sector. Therefore, in example 1 the thicknesses of the different layers are configured to obtain glazing that has a low solar factor, while in example 5 the objective was, in contrast, to maximize light transmittance in the visible region through the glazing. The glazed articles synthesized using conventional techniques were heated and tempered using conventional field techniques (heated to 620°C for 10 minutes, followed by tempering). Table 1 below contains information relating to the composition of the solar control glazing according to examples 1 to 5 of the invention, based on the surface of the glass: rocfrnn / zznz / E / YiAi [Table 1] Thickness 1st layer SÍ3N4 Thickness 1st layer of NbNx Thickness ITO Layer Thickness 2nd layer of NbNx Thickness 2nd layer of SÍ3N4 Example 1 100 14 41 6 18 Example 2 53 9 50 11 56 Example 3 60 6 55 8 41 Example 4 5 3 20 2 23 rocfrnn / zznz / E / YiAi The light transmission (Tl) and external light reflection (Rext) values, as well as the internal light reflection (Rint), were measured in the 380 nm to 780 nm range using the methods described in standard NF EN 410 (2011). This same standard was also used to measure the solar g-factor of the substrate equipped with its battery. The results obtained are collected in Table 2 below, in percentage: [Table 2] Tl Rhext RLint 9 Tl / q Example 1 20 21 9 27 0.74 Example 2 22 5 3 29 0.76 Example 3 30 7 8 39 0.78 Example 4 51 22 18 54 0.94 The colorimetric values ​​for transmission, internal reflection, and external reflection according to L, a*, b* are indicated in Table 3 below: [Table 3] a*TL b*TL a*RLext b*RLext a*RLint b*RLint Example 1 0.2 4.4 -7.6 0.2 1.8 -7.7 Example 2 0.6 -0.1 0.0 -2.9 -8.9 0.0 Example 3 0.6 0.8 -5.4 -1.6 -2.6 -6.3 Example 4 -1.1 -0.2 -3.1 -4.9 -0.7 1.5 The results shown in the tables above indicate that the glazing obtained according to examples 1 to 3 had a solar factor well below 50%, which guarantees good thermal insulation of the building or passenger compartment. The glazing according to example 4 was configured to improve light transmission in the visible range, which explains the higher solar factor. However, the solar factor remains close to 50%, and the selectivity is significantly higher and close to 1. This means that the radiation in the infrared range is selectively reflected and / or absorbed by the glazing. As can be seen from Table 3, all four glazings have a remarkably neutral color in transmission. Regarding the color of the inner surface of the glazing, the glazing according to examples 1 to 3 has a low Runt light reflectance, allowing the occupants of the building or room to easily see outside. The glazing according to example 4 has a significantly higher interior light reflectance, but very neutral a* and b* values ​​for internal reflection, so it appears colorless to the occupants of the building or room. It can be observed that the values ​​of the coefficients a* and b* are relatively low and in all cases less than or equal to 5, which expresses a relative neutrality of the perceived color in both reflection and transmission. Comparative Examples It is possible to compare with the properties of the stacks in patent application WO 01 / 21540 mentioned above. Example 4 of patent application WO01 / 21540 describes a succession of layers in the stack: Glass / Si3N4 (10 nm) / Nb (12 nm) / Si3N4 (17 nm). The table on page 18 of this publication indicates that the light transmittance is 32.3% and the light reflectance is 25.3%. The solar g-factor can be calculated to be approximately 36%. If the selectivity is comparable to that of the glazing according to the invention, the internal reflectance value appears very high when metallic niobium is used as a reflective / absorbing functional layer. Similarly, example 6 of patent application WO01 / 21540 describes a sequence of layers in the stack: Glass / S¡3N4 (10 nm) / Nb (10 nm) / S¡3N4 (15 nm). In the table on page 18 of this publication, the reported values ​​for Tl and Runt are 31% and 28%, respectively. The solar g-factor can be assumed to be approximately 48% for the pile. The calculated selectivity g for this configuration (65%) is lower than that obtained for glazing according to the invention. Furthermore, the external reflection is also much higher for this configuration.

Claims

1. A transparent glazing article, characterized in that it comprises at least one glass substrate equipped, on at least one of its faces, with a coating consisting of a stack of thin layers, the coating comprising the following sequence of layers, with reference to the surface of the substrate: a first layer comprising niobium nitride, a layer comprising a transparent conductive oxide, a second layer comprising niobium nitride, wherein the first and second layers comprising niobium nitride are in direct contact with the layer comprising a transparent conductive oxide.

2. The article according to claim 1, further characterized in that the layer comprising a transparent conductive oxide has a thickness between 5 nm and 400 nm.

3. The article according to one of the preceding claims, further characterized in that the first layer comprising niobium nitride has a thickness between 1 and 50 nm.

4. The article according to one of the preceding claims, further characterized in that the second layer comprising niobium nitride has a thickness between 1 and 50 nm.

5. The article according to any of the preceding claims, further characterized in that the transparent conductive oxide is selected from indium-tin oxides (ITO), aluminum-zinc oxides (AZO), antimony-tin oxides (ATO) and indium-zinc oxides (IZO), and preferably from indium-tin oxides (ITO).

6. The article according to one of the preceding claims, further characterized in that the transparent conductive oxide is selected from a tin oxide that is doped to make it conductive, preferably with an element selected from F, Sb, Al and Ag, preferably fluorine or antimony.

7. The article according to one of the preceding claims, further characterized in that the layer comprising a transparent conductive oxide is thicker than the first and second layers comprising niobium nitride.

8. The article according to one of the preceding claims, further characterized in that the battery does not comprise functional layers based on Ag, Au, Pt, Cu, Ni or stainless steel.

9. The article according to one of the preceding claims, further characterized in that at least one layer of a dielectric material is placed on the succession of layers, with reference to the substrate surface.

10. The article according to one of the preceding claims, further characterized in that at least one layer of a dielectric material is placed beneath the succession of layers, with reference to the substrate surface.

11. The article according to any of claims 9 and 10, further characterized in that the dielectric material is selected from nitrides, in particular silicon nitride and aluminum nitride and mixtures thereof, or oxides, in particular silicon oxide, titanium oxide, tin oxide, zinc oxide and mixtures thereof.

12. The article according to one of the preceding claims, further characterized in that a layer comprising silicon nitride is placed on and / or under the succession of layers.

13. The article according to the preceding claim, further characterized in that the battery rocfrnn / zznz / E / YiAi comprises or consists of the succession of the following layers, each layer being in direct contact with the next: SiNx / NbNx / TCO / NbNx / SiNx wherein SÍNX designates the layers comprising silicon nitride, NbNx designates the layers comprising niobium nitride and TCO designates the layers comprising a transparent conductive oxide, the transparent conductive oxide preferably being an indium tin oxide.

14. The article according to any one of the preceding claims, further characterized in that at least one layer comprising a metal oxide is present between the surface of the glazed substrate and the succession of layers, the metal oxide being preferably selected from silicon oxide and titanium oxide. 10 15. The article according to one of the preceding claims, further characterized in that at least one layer comprising a metal oxide is present on the succession of layers, the metal oxide being preferably selected from silicon oxide, titanium oxide, zirconium oxide and a mixture of these oxides.

16. The article in accordance with one of the preceding claims, further characterized in that it is thermally tempered and / or bent.