WO2005105687A2

WO2005105687A2 - Glazing comprising a stack of thin layers which act on solar radiation

Info

Publication number: WO2005105687A2
Application number: PCT/FR2005/050274
Authority: WO
Inventors: Sylvain Belliot; Valérie COUSTET
Original assignee: Saint-Gobain Glass France
Priority date: 2004-04-28
Filing date: 2005-04-25
Publication date: 2005-11-10
Also published as: FR2869606B1; CN101061077A; CN101061077B; FR2869606A1; WO2005105687A3

Abstract

The invention relates to a transparent substrate which is equipped with a stack of thin layers which act on solar radiation. The aforementioned stack comprises: a functional layer which is made from metal (Nb, Ta, Zr) or a nitride of said metal, and an overlayer and an underlayer which are made from aluminium nitride or oxynitride and/or silicon nitride or oxynitride.

Description

GLAZING PROVIDED WITH A STACK OF THIN FILMS ACTING ON THE SOLAR RADIATION

The invention relates to glazings fitted with stacks of thin layers acting on solar radiation, in particular those intended for thermal insulation and / or solar protection. This type of glazing is more particularly suitable for equipping buildings: by acting, thanks to the thin layers, on the amount of energy of the solar radiation, it makes it possible to avoid inside the premises an excessive heating in summer and thus contributes to limit the energy consumption necessary for their air conditioning. The invention also relates to this type of glazing once opacified so as to be part of a facade cladding panel, called more concisely lightened, and which makes it possible, in association with glazing for vision, to offer exterior surfaces of fully glazed buildings. These layered glazing (and lighters) are subject to a certain number of constraints: as regards glazing, the layers used must be sufficiently filtering with respect to solar radiation. In addition, these thermal performances must preserve the optical appearance, the aesthetics of the glazing: it is desirable to be able to modulate the level of light transmission of the substrate, and to keep an aesthetic color, very particularly in external reflection. This is also true of the lighters with regard to the aspect in reflection. These layers must also be sufficiently durable, and this is all the more so if, in the glazing once mounted, they are on one of the outer faces of the glazing (as opposed to the "inner" faces, facing the interlayer of gas. double glazing for example). Another constraint is gradually imposed: when the glazing consists at least in part of glass substrates, these may have to undergo one or more heat treatments, for example a bending if one wishes to give them a curve (window), a quenching or a annealing if we want them to be more resistant / less dangerous in the event of impact. The fact that layers are deposited on the glass before its heat treatment risks causing their deterioration and a significant modification of their properties, in particular optical properties (depositing the layers after the heat treatment of the glass is complex and costly). A first approach consists in providing for the change in optical appearance of the glass due to the layers after the heat treatment, and in configuring the layers so that they do not exhibit the desired properties, in particular optical and thermal, only after this treatment. But in fact, this means that two types of layer stacks have to be produced in parallel, one for the non-toughened / non-curved glazing and the other for the glazing which is going to be toughened / curved. We are now trying to avoid this, by designing stacks of thin (interference) layers that can be able to withstand heat treatments without modifying the optical properties of the glass too significantly and without degrading its appearance (optical defect). We can then speak of "bendable" or "quenchable" layers. An example of anti-solar glazing for the building is given by patents EP-0 511 901 and EP-0 678 483: these are functional layers in terms of filtration of solar radiation which are made of nickel-chromium alloy , possibly nitride, made of stainless steel or tantalum, and which are placed between two layers of dielectric in metal oxide such as SnO2, ΗO2 or TaaOs. These glazings are good anti-solar glazings, having satisfactory mechanical and chemical durability, but are not really "bombable" or "quenchable", because the oxide layers surrounding the functional layer cannot prevent its oxidation during bending or tempering, oxidation accompanied by a modification of the light transmission, and of the appearance in general of the glazing as a whole. Many studies have been carried out recently to make the layers bumpable / hardenable in the field of low-emissivity glazing, rather targeting high light transmissions unlike anti-solar. It has already been proposed to use, above functional silver layers, dielectric layers based on nitride of silicon, this material being relatively inert with respect to oxidation at high temperature and proving capable of preserving the underlying silver layer, as described in patent EP-0 718 250. D ' other stacks of layers acting on the presumably bendable / hardenable solar radiation have been described, using functional layers other than silver: patent EP-0 536 607 uses functional layers of metallic nitride, of the TiN or CrN type, with protective layers of metal or of silicon derivatives, patent EP-0 747 329 describes functional layers of nickel alloy of the NiCr type associated with layers of silicon nitride. However, these stacks with an anti-solar function have performances which are still capable of improvement, in particular in terms of limiting their light reflection. The term "functional" layer is understood in the present application to be the layer (s) of the stack which gives the stack most of its thermal properties, in contrast to the other layers, generally made of dielectric material, having as role that of a chemical or mechanical protection of the functional layers, an optical role, a role of adhesion layer, etc. The aim of the invention is then to develop a new type of stacks of thin layers acting on solar radiation, with a view to manufacturing improved solar protection glazing. The improvement targeted is in particular the establishment of a better compromise between thermal properties, optical properties and the ability to withstand thermal treatments without damage when the substrate carrying the stack is of the glass type. The other object of the invention is to make this stack of layers compatible with the use of the glazing, once opacified, as a lighter. The object of the invention is first of all a transparent substrate, in particular made of glass, provided with a stack of thin layers acting on the solar radiation and which comprises at least one functional layer of essentially metallic character and mainly comprising at least one of the metals belonging to the group of niobium, tantalum, zirconium, interposed between at least one overlayer and at least one sublayer, which are based on silicon nitride or oxynitride, or based on aluminum nitride or oxynitride or a mixture of at least two of these compounds (nitrides or oxynitrides (Si-Al). Alternatively, the functional layer according to the invention may be based on a metal partially or entirely nitride, said metal belonging to the group of niobium, tantalum, zirconium. The combination of these types of functional layer and of these types of overcoat and undercoat has proven to be extremely advantageous for sun protection glazing: the functional layers of type Nb, Ta, Zr are particularly stable and, independently of the nature of the overcoat, are in themselves more suitable than other functional layers already used in the same type of application for undergoing various heat treatments. It has been shown that, for example, niobium, niobium nitride tends to oxidize less than other metals such as titanium or nickel, and that the selected metals are also more stable than Ni alloys. Cr containing a significant amount of chromium, since chromium has a tendency to diffuse under the effect of heat to the adjacent layers and glass, and to cause the stack of layers as a whole to evolve optically. functional layers of the invention allow the light transmission value of the substrate to be adjusted in the desired ranges detailed below, by adjusting their thicknesses, while retaining a significant anti-solar effect, even at relatively high light transmission: they are in a sufficiently selective word, making it possible in particular to achieve good compromises between light transmission level (TL) and solar factor (FS) (the solar factor is defined as the ratio between e the total energy entering a room through the glazing and the incident solar energy). We can define as a "good" compromise the fact that the values of T and FS of an insulating glazing are close to each other, with for example an Fs of at most 5 to 10 points higher than that TL, in particular at most 2 to 3% higher than that of T _L. This compromise can also be expressed by comparing the values of TL and energy transmission TE, a "good" compromise being obtained when the value of TE is close to that of TL, for example plus or minus 5, in particular plus or minus 2 to 3% relative to that of TL. The choice of an overlay and an undercoat based on silicon nitride or aluminum (Si3N ₄ and AIN for short) or in oxynitride of silicon or aluminum (SiON and A1NO for short, without prejudging respective amounts of Si, O and N) have also proved to be very advantageous for several reasons: this type of material has been found capable of protecting the functional layers of the invention at high temperature, in particular with respect to the oxidation, while preserving their integrity, which made the stack according to the invention bomable / quenchable in the case where the substrate carrying the stack is made of glass and that it is desired to subject it to such a heat treatment after deposition layers In addition, its refractive index, close to 2, is similar to that of metallic oxides of the SnO ₂ type, ZnO: it acts optically similar to these, without any particular complication. It also protects mechanically and chemically, the rest of the stack. In addition, the inventors have discovered quite unexpectedly that a substantial increase in the thickness of the undercoat makes the undercoat significantly rougher. This increase in roughness is transmitted to all of the layers. deposited on this sublayer and in particular at the level of the functional layer. This roughness, added to the intrinsic absorbent nature of the functional layer, further increases its absorbent nature by creating a phenomenon of light trap. These two contributions make it possible to obtain a significant reduction in light reflection. Finally, it has been discovered that it is also compatible with a subsequent enamel treatment, which is of particular interest to the lighters. In fact, in order to opaque window panes, there are generally two possible ways: either deposit a lacquer on the glass, which is dried and hardened with a moderate heat treatment, or deposit an enamel. The enamel as it is deposited in the usual way is composed of a powder containing a glass frit (the vitreous matrix) and pigments used as colorants (the frit and the pigments being based on oxides metallic), and a medium also called a vehicle allowing the application of the powder to the glass and its adhesion with the latter at the time of deposition. To obtain the final enamel coating, it must then be baked, and it is frequent that this baking operation is carried out concomitantly with the tempering / bending operation of the glass. Reference may be made for more details to enamel compositions in the patents FR-2 736 348, WO96 / 41773, EP-718 248, EP-712 813, EP-636 588. The enamel, mineral coating, is durable , adherent to glass and therefore an interesting opacifying coating. However, when the glazing is previously provided with thin layers, its use is delicate for two reasons:

** ^• on the one hand, baking the enamel means having to subject the stack of layers to a high temperature heat treatment, which is only possible if the latter is capable of not deteriorating optically during this treatment, ** ^• on the other hand, the enamel tends to release over time chemical substances which come to diffuse in the underlying layers and modify them chemically. However, using a layer of silicon nitride or oxynitride of aluminum to finish the stacking of thin layers has been very effective, both to make the entire stack capable of withstanding heat treatments and to act as a barrier to these chemical compounds capable of diffusing out of the enamel layer. In fact, the stack of layers according to the invention can be glazed, in the sense that an enamel can be deposited on it and baked without significantly modifying the optical appearance with respect to vision glazing provided with the same layers, in external reflection. And this is precisely the issue of the lighters, namely to offer a harmony of color, the greatest possible similarity in external appearance with the glazing, in order to be able to constitute aesthetic entirely glazed facades. Combining the functional layers and the overlay and underlay according to the invention has yet another advantage: if Si3N ₄ , SiON, TAIN or AlNO have the very interesting properties mentioned above, they also tend to have adhesion problems with many metallic layers. This is particularly the case of layers in money. It is then necessary to have recourse to means for increasing this adhesion and avoiding delamination of the stack: it is in particular possible to interpose adhesion layers, for example thin layers of metal or based on zinc oxide having good compatibility between the two materials in question. The presence of these adhesion layers is unnecessary in the context of the invention. Thus, it has been possible to verify that the functional layers of the invention, in particular those made of Nb, adhere very satisfactorily to the layers of Si3N ₄ , SiON, AIN or A1NO, using a sputtering deposition technique, in particular assisted by magnetic field. Optionally, the stack of layers according to the invention can also comprise, between the substrate and the functional layer, at least one sublayer of transparent dielectric material, in particular chosen as for the overlayer of silicon nitride or oxynitride and / or aluminum nitride or oxynitride, or in silicon oxide Si encore2- In addition, due to the presence of a sublayer, between the substrate and the functional layer, based on nitride or silicon oxynitride and / or aluminum nitride or oxynitride, or even in silicon oxide Siθ2, makes it possible to more flexibly modulate the optical appearance imparted by the stack of layers to its carrier substrate. In addition, in the case of heat treatment, it constitutes an additional barrier, in particular with respect to oxygen and alkalis of the glass substrate, species liable to migrate to heat and to degrade the stack. A preferred embodiment consists in using both an underlay and an overlay of nitride or oxynitride, in particular both based on silicon nitride. It has been found advantageous, in this case, to provide, according to one embodiment, for the undercoat to be thicker than the overcoat, for example by at least a factor of 2: it may even have a thickness 3 times more large (by reasoning in geometric thickness). It has indeed been shown in the present invention that thicker undercoats guarantee better optical stability with respect to treatments. thermal type quenching, and in particular allowed to limit the external reflection of the substrate. The stack of layers according to the invention can also optionally comprise, above and / or below the functional layer, an additional layer of a nitride of at least one metal chosen from niobium, titanium, zirconium , chromium. In fact, it can therefore be interposed between the functional layer and the overlay and / or between the functional layer and the substrate (or between the functional layer and the underlay when there is one). When the functional layer is itself made of nitride, it is therefore possible to have the superposition of two layers of nitride of different metals. This additional nitride layer has been shown to be able to more finely adjust the color in external reflection of the stack, thanks to the reduction in the thickness of the functional layer which it allows: it is thus possible to "replace" a part of the thickness of the functional layer by this additional layer. Advantageously, the layer or layers of the stack which are based on silicon nitride or oxynitride also contain a minority metal with respect to silicon, for example aluminum, in particular up to 10% by weight of the constituent compound. the layer in question. This is useful for accelerating the deposition of the layer by sputtering assisted by magnetic field and reactive, where the target in silicon without a "doping" by a metal is not sufficiently conductive. The metal can further impart better durability to the nitride or roxynitride. As regards the thicknesses of the layers described above, a range of thickness of 5 to 50 nm is usually chosen for the functional layer, in particular between 8 and 40 nm. The choice of its thickness makes it possible to modulate the light transmission of the substrate in ranges used for solar protection glazing for the building, namely in particular from 5 to 50% or from 8 to 45%. Of course, the level of light transmission can also be modified using other parameters, in particular the thickness and composition of the substrate, whether it is made of clear or particularly colored glass. The thickness of the overlayer is preferably between 5 and 70, in particular between 10 and 35 nm. It is for example 15, 20 or 30 nm. The thickness of the sublayer is preferably between 50 and 120 nm, in particular between 70 and 100 nm. When it is a single sub-layer, of the Si3N ₄ type, it is for example from 70 to 100 nm. If it is a sequence of several layers, each of the layers may have a thickness of for example 5 to 50 nm, in particular 15 to 45 nm. The sublayer and the overlayer may in fact be part of a superposition of layers of dielectric material. Either can thus be associated with other layers of different refractive indices. Thus, the stack of layers may comprise between the substrate and the functional layer (or above the functional layer) an alternation of three high index / low index / high index layers, the "high index" layer (at least 1.8 to 2) or one of them which may be the sub-layer of the invention of the S-3N4, AIN type, and the “low index” layer (less than 1.7 for example) be made of silicon oxide Siθ2. The thickness of the additional layer of metallic nitride is preferably between 2 and 20 nm, in particular between 5 and 10 nm.

It is therefore preferably fine, and therefore does not participate, if any, in a very minority in the sun protection effect imparted by the metal layer. A preferred embodiment of the invention is a stack comprising a functional layer based on niobium or niobium nitride, an overlayer based on silicon nitride, an optional sublayer also based on silicon nitride. The subject of the invention is also the substrate provided with the stack of layers described above, in general, and which is bendable and / or hardenable and / or enamelled. For the purposes of the invention, the term “bombable and / or hardenable” means a stack, which, deposited on a substrate, undergoes a limited optical evolution, which can in particular be quantified by placing it in the colorimetry system (L *, a *, b *), by a value ΔE less than 3, in particular less than 2. As follows is defined .DELTA.E: .DELTA.E = (.DELTA.L ² + .DELTA.a ² + .DELTA.b ²⁾ ^{^1/2,} with .DELTA.L, .DELTA.a and .DELTA.b the difference in the measurements of L *, a * and b * before and after heat treatment. We consider as "enamelable" the stack on which we can deposit in a known manner an enamel composition, without the appearance of optical defects in the stack and with a limited optical evolution, which can be quantified as above. This also means that it has satisfactory durability, without annoying deterioration of the layers of the stack in contact with the enamel either during its firing, or over time once the glazing has been mounted. Of course, a stack of this type is advantageous when using substrates made of clear glass or tinted in the mass. However, one can just as easily not seek to exploit its bombable / hardenable nature, but simply its satisfactory durability, by using glass substrates but also non-glass substrates, in particular in rigid and transparent polymer material such as polycarbonate, polymethyl methacrylate. (PMMA) replacing glass, or a flexible polymeric material, like certain polyurethanes or like polyethylene terephthalate (PET), flexible material which can then be fixed to a rigid substrate to functionalize it, by making them adhere by different means , or by a leafing operation. The subject of the invention is "monolithic" glazing (that is to say consisting of a single substrate) or multiple insulating glazing of the double glazing type. Preferably, whether it is monolithic glazing or double glazing, the stacks of layers are arranged on face 2 (conventionally, the faces of the glasses / substrates of a glazing are numbered from the outside to the inside of the interior / of the room it equips), and provide a protective effect against solar radiation. The glazings of particular interest to the invention have a TL of the order of 5 to 50%, in particular 8 to 45%, and a solar factor FS of less than 50%, in particular close to the value of T _L. They also preferably have a blue or green color in external reflection (on the side of the substrate devoid of layers), with in particular in the colorimetry system (L *, a *, b *) negative values of a * and b * (before and after any possible t-hermetic treatment). We thus have a pleasant shade and not very intense in reflection, sought after in the building. The invention also relates to the substrate with layers at least partially opacified by a coating of lacquer or enamel type, with a view to making lighters, where the opacifying coating is in direct contact with the stack of layers. The stacking of layers can therefore be perfectly identical for vision glazing and for lighters. If the application more particularly targeted by the invention is glazing for the building, it is clear that other applications are possible, in particular in vehicle glazing (apart from the windshield where very high light transmission), like the side windows, the car roof, the rear window. The invention will be described below in more detail with the aid of non-limiting examples. All substrates are 6 mm thick clear glass of the type

Planilux marketed by Saint-Gobain Vitrage. All the layers are deposited in a known manner by sputtering assisted by a magnetic field: the metal layers from a metal target in an inert atmosphere (100% Ar), the layers of metal or silicon nitride from the target of metal or silicon (doped with 8% by mass of aluminum) suitable in a reactive atmosphere containing nitrogen (100% N ₂ for TiN, 40% Ar and 60% N ₂ for syN). The Si3N ₄ layers therefore contain a little aluminum. EXAMPLE 1 This example uses a functional layer of Nb and an overlayer of Si ₃ N4 according to the following sequence: glass / Nb (30 nm) / Si3N ₄ (31 nm) After deposition of the layers, the substrate undergoes the following heat treatment: heating at 620 ° C for 10 minutes. EXAMPLE 2 This example uses the same functional layer and the same overlay as in Example 1, with an additional S-layer: bN4 according to the following sequence: glass / Si3N ₄ (8 nm) / Nb (30 nm ) / S13N4 (28 nm) the coated substrate then undergoes the same heat treatment as in Example 1. EXAMPLE 3:

This example uses the same functional layer and the same overlay as in Example 1, with an Si3N4 sublayer according to the invention: glass / S-3N4 (85 nm) / Nb (30 nm) / S-3N4 (28 nm) the coated substrate then undergoes the same heat treatment as in Example 1. EXAMPLE 4: This example uses the same sequence of layers as in Example 2, but with slight modifications in their thicknesses: glass / S-3N4 (83 nm) / Nb (33 nm) / Si3N ₄ (33 nm) After deposition of the layers, the substrate is enamelled on its face coated with the stack of layers. The enamel composition is standard, for example of the type described in a patent cited above as FR-2 736 348, remeshing is carried out in a known manner with a heat treatment for baking the enamel at around 620 ° C. EXAMPLE 5 This example uses the sequence of layers of Examples 2 and 3, but with a lower functional layer thickness, in order to target glazing with higher light transmission: glass / S13N4 (10 nm) / Nb (12 nm) / Si3N ₄ (17 nm) The coated substrate then undergoes the same heat treatment as in Example 1. EXAMPLE 6:

This example repeats the sequence of layers of Example 4 with a sublayer according to the invention: glass / SisN ₄ (85 nm) / Nb (12 nm) / SisN4 (17 nm) The coated substrate is then subjected to the same treatment as in Example 1. EXAMPLE 7 This example illustrates another variant of the invention where the functional layer is made of metallic nitride, here niobium nitride. The sequence of layers is as follows: glass / S-3N4 / NbN (10 nm) / S-3N4 (15 nm) The layers of S-3N4 are obtained as previously, the layer of NbN is obtained from a niobium target in a reactive atmosphere at 30 % nitrogen by volume. EXAMPLE 8:

This example repeats the sequence of layers of Example 4 with a sublayer according to the invention: glass / S-3N4 (75) / NbN (15 nm) / Si3N ₄ (10 nm) The coated substrate then undergoes the same heat treatment as in Example 1.

COMPARATIVE EXAMPLE 1 This example serves as a comparison with Example 1: instead of a functional layer of Nb, it uses a functional layer of NiCr 40/60 alloy by weight. The layer sequence is as follows: glass / NiCr (30 nm) / S - 3N4 (27 nm) The coated glass then undergoes the same heat treatment as example 1. COMPARATIVE EXAMPLE 2 This example serves to compare with Example 2: it uses a functional layer of NiCr 40/60 by weight instead of a functional layer of Nb. The sequence of layers is as follows: glass / S - 3N4 / NiCr (30 nm) / S-3N4 (27 nm) The coated glass then undergoes the same heat treatment as in Example 1.

COMPARATIVE EXAMPLE 3

This example serves as a comparison with Example 3: it uses a functional layer of NiCr 40/60 by weight instead of a functional layer of Nb and an underlayer according to the invention. The sequence of layers is as follows: glass / S.3N4 (85) / NiCr (30 nm) / S.3N4 (27 nm) The coated glass then undergoes the same heat treatment as in Example 1. Table 1 below groups together for Examples 1, 2, Comparative 1 and Comparative 2 the following data: optical transmission TL: light transmission in% according to the illuminant Des λdom (τ): the dominant wavelength of the color in transmission in nm, pe {τ): the excitation purity of the color in transmission, in%, external reflection (i.e. that measured on the external side, when the coated glass is mounted in monolithic glazing in a room with the stack of layers on face 2: external reflection (RLEXT) in%, a * (RExτ), b * (Rεxτ) the colorimetric coordinates in external reflection according to the colorimetry system (L, a *, b *), internal reflection: the value of RLINT in%, and the colorimetric data a * (RiNτ), b * (RiNτ), energy transmission: TE in% All these data are indicated twice: before heat treatment and after thermal treatment. also in ΔE (T) transmission, in reflection Outdoor .DELTA.E (REXT) and .DELTA.E internal reflection (R _1N τ), with .DELTA.E = (.DELTA.L ² + .DELTA.a ² + .DELTA.b ²⁾ ^{^1/2} for transmission, with: .DELTA.a = a * (after treatment) - a * ( before treatment), Δb = b * (after treatment) - b * (before treatment) ΔL = L * (after treatment) - L * (before treatment)

O

TABLE 1

This table shows that examples 1, 2 and 3 according to the invention offer a good TL / TE compromise before heat treatment, with values of TL and TE close: they offer good sun protection. They are also good from an aesthetic point of view, especially in external reflection where the values of a * and b * are negative and, in absolute values which are not high, at most 2.7:. What is noteworthy is that all these advantages are retained after heat treatment: the values of TL and TE are kept to within 1%, the colorimetric data change very little, there is no switching from a shade to another shade in exterior reflection. There are no optical defects. The value of ΔE, quantifying a possible colorimetric evolution, remains at most 2.7 in transmission, in internal and external reflection, with an ΔE of only 1.6 in external reflection: it is indeed a suitable stack to undergo without significant degradation a bending or quenching treatment. Whether a tempered glass, annealed, curved or not, the invention provides an anti-solar stack with identical properties, preserved. The remarks made with regard to example 1 also apply to example 2, with an even lower optical evolution: a ΔE of only 0.3 in external reflection in particular. It can be seen that it is advantageous to provide a sub-layer of S-3N4 that is at least 70 to 90 nm thicker: there is gain in quenchability, and above all, the level of external reflection is significantly reduced. The results of Comparative Examples 1, 2 and 3 are much less good: these stacks are clearly not bendable / hardenable within the meaning of the invention: the values of TL and TE change a lot. In Comparative Example 1, we go from 11.5 to almost 20% in TL. The values of ΔE in internal and external reflections for Comparative Example 1 are at least three times greater than those obtained according to the invention, and the sign of b * changes in external reflection: there is a tipping of shade. This confirms the fact that it is preferable to eliminate or limit as much as possible the presence of chromium in the functional layers (for example at most 20%, in particular at most 10 or at most 5% by weight), chromium probably having a role, by its propensity to diffuse at high temperature, in these modifications. Table 2 below provides data already explained for Table 1 with regard to Example 3 where an enameling was carried out on the layers: the values of RLEXT, a * (RExτ) and b * {RE τ) were measured before and after enamelling (same mounting of the glazing which has become a lighter than in table 1: monolithic glass, layers and enamel on face 2). TABLE 2

It is verified that the color remains substantially the same in external reflection after enameling with a ΔE less than 1. There is also no significantly higher aging of the sill than in the case of a standard sill, with the same enamel deposited directly on the. _s glass. According to the invention, the stack uses a functional layer of niobium or tantalum, an overlayer of silicon nitride, a sublayer of silicon nitride also, and an optional layer of titanium nitride or niobium nitride directly on or directly under the functional layer. As a variant of the invention, the stack uses a functional layer of niobium nitride, an overlayer of silicon nitride, and also a sublayer of silicon nitride. Table 3 below groups together the data already explained above, for examples 5 to 8 (same configuration in monolithic glass with the layers opposite 2).

^• to

TABLE 3

Claims

1. Transparent substrate, provided with a stack of thin layers acting on the solar radiation, said stack comprising at least one functional layer of essentially metallic character and mainly comprising at least one of the metals belonging to the group of niobium, tantalum, zirconium , said functional layer being surmounted by at least one overlayer based on aluminum nitride, aluminum oxynitride, silicon nitride, or silicon oxynitride, or a mixture of at least two of these compounds, said stack also comprising between the substrate and the functional layer at least one sublayer of transparent dielectric material, in particular chosen from silicon and / or aluminum nitride, silicon and / or aluminum oxynitride and silicon oxide, characterized in that the sublayer has a thickness between 50 and 120 nm, in particular between 70 and 90 nm.

2. Transparent substrate, provided with a stack of thin layers acting on solar radiation, characterized in that said stack comprises at least one functional layer based on a metal partially or entirely nitride, said metal belonging to the niobium group, tantalum, zirconium, said functional layer being positioned between at least one overlayer based on aluminum nitride or oxynitride, silicon nitride or oxynitride, or a mixture of at least two of these compounds and at least one sublayer based on alumirrium nitride or oxynitride, silicon nitride or oxynitride, or a mixture of at least two of these compounds

3. Substrate according to one of claims 1 or 2, characterized in that the stack comprises an overlay based on nitride or oxynitride and a sublayer based on nitride or oxynitride, the geometric thickness of the sublayer being greater than that of the overlayer.

4. Substrate according to one of claims 1 to 3, characterized in that said overlay and said undercoat are based on silicon nitride.

5. Substrate according to one of the preceding claims, characterized in that the underlayment is thicker than the overlay by at least a factor of between 2 and 3

6. Substrate according to one of the preceding claims, characterized in that the stack comprises a plurality of sub-layers between the substrate and the functional layer, in particular an alternation of high and low index layers such as Si3N4 / Siθ2 / Si3N4.

7. Substrate according to one of the preceding claims, characterized in that the stack also comprises an additional layer of a nitride of at least one metal chosen from niobium, titanium, zirconium between the functional layer and the overlay and / or between the functional layer and the substrate.

8. Substrate according to one of the preceding claims, characterized in that the functional layer has a thickness between 5 and 50 nm, in particular between 8 and 40 nm.

9. substrate according to one of the preceding claims, characterized in that the thickness of the overlayer is between 5 and 70 nm, in particular between 10 and 35 nm.

10. Substrate according to claim 7, characterized in that the additional layer of metallic nitride has a thickness between 2 and 20 nm, in particular between 5 and 10 nm.

11. Substrate according to one of the preceding claims, characterized in that the stack uses a functional layer of niobium or tantalum, an overlayer of silicon nitride, a sublayer of silicon nitride also, and an optional layer of titanium nitride or niobium nitride directly on or directly under the functional layer.

12. Substrate according to one of claims 1 to 10, characterized in that the stack uses a functional layer of niobium nitride, an overlayer of silicon nitride, a sublayer of silicon nitride also.

13. Substrate according to one of the preceding claims, characterized in that it is bendable / quenchable and / or enamelable.

14. Substrate according to one of the preceding claims, characterized in that it is made of glass, clear or tinted in the mass, or of material flexible or rigid transparent polymer.

15. Monolithic glazing or double glazing incorporating the substrate according to one of the preceding claims, the stack of thin layers, preferably being located on face 2 and by numbering the faces of the substrates from the outside towards the inside of the passenger compartment / the room it equips, giving it a protective effect against solar radiation.

16. Glazing according to claim 15, characterized in that it has a light transmission T _L of 5 to 50%, in particular from 8 to 45%, and a solar factor FS less than 50%, in particular close to the transmission value. light.

17. Glazing according to claim 15 or 16, characterized in that it is blue or green in external reflection, on the substrate side, with in particular negative values of a * and b *.

18. Substrate according to one of claims 1 to 14, characterized in that it is at least partially opacified by a coating in the form of a lacquer or an enamel.

19. Lightweight facade cladding panel incorporating the opacified substrate according to claim 18.