KR19990008413A - Method for depositing reflective layer on glass and products thereof - Google Patents

Abstract

The gist of the present invention is a method of particularly continuously depositing a reflective layer 3 based on a metal whose melting point is below the temperature at which the glass ribbon obtains dimensional stability on the glass ribbon 10 of the float line. When the glass ribbon 10 has already obtained dimensional stability, by contacting the surface of the ribbon with this metal 22 in powder or molten form, the deposition is carried out in an inert or reducing atmosphere, The temperature of the ribbon is solid continuous at the surface of the ribbon when the powder melts and coalesces, or when the molten metal forms a sheet and the temperature of the ribbon falls below the melting point of the metal during the flat glass forming process. It is selected to leave a layer.

Description

Method for depositing reflective layer on glass and products thereof

The metal layer adds various properties to the glass substrate intended to be in the glazing panel, depending on its thickness, i.e. at a relatively low thickness, this metal layer acts as a protective coating against solar radiation and / or a low radiation coating. . At higher thicknesses, the metal layer allows mirrors with very high light reflectivity to be obtained.

The most widespread example is silver, which is deposited using a vacuum technique in the form of sputtering, in particular as a thin film with interference thickness, or as a thick layer for making mirrors, for example using conventional wet techniques of silver plating lines. Known. However, when silver is exposed to a chemically active medium, silver as a thin film has limited durability, and the above-described deposition technique is a discontinuous, subsequent step on a glass plate once cut from the glass ribbon of a float production line. Can only be performed in

Thus, other metals, such as aluminum, which have similar properties to silver but can be deposited directly on the glass ribbon of the float line continuously, less expensively and have good durability, are contemplated.

Deposition of an aluminum layer on a glass ribbon in a chamber of a float bath, using molten aluminum to release vapor condensed on the surface of the glass ribbon for continuous coating, is known from French Patent No. 2,011,563. However, this type of technique has the following drawbacks: it is difficult to realize, it is not easy to achieve a single thickness of deposition, and above all, the deposition rate is low and the partial vapor pressure of the metal aluminum is very low.

From the British patent (GB-A-2,248,853) it is known to deposit an aluminum layer on a ribbon of float glass at a temperature of at least 100 ° C. The technique used here is one of pyrolysis in the liquid state, in which the organometallic mixture is sprayed towards the glass and decomposed into the metal of the element as it reaches the contact surface. This type of pyrolysis cannot avoid the following drawbacks: discharge is required and a large amount of solvent must be treated.

The present invention relates to a method of depositing a reflective layer, and more particularly to a method of depositing a metal layer on glass.

1 is a cross-sectional view of a coated glass substrate according to the present invention.

2 is a cross sectional view of a portion in which a deposition of a metal reflective layer according to the invention is carried out in a float glass chamber;

It is an object of the present invention to develop a new fixation for continuously manufacturing a metal reflective layer on a ribbon of float glass, which alleviates the above-mentioned drawbacks, and in particular enables to obtain a high quality layer that meets the needs of industrial production of glazing. will be.

The subject of this invention is the method of continuously depositing the reflective layer based on the metal whose melting point is below the temperature at which a glass ribbon acquires dimensional stability, on the glass ribbon of a float line. When the glass ribbon has already obtained this dimensional stability, this point is present in contacting the surface of the ribbon with this metal in powder form or in molten form to effect deposition in a reducing atmosphere under inertness or control and The temperature of the ribbon on the way is chosen such that the powder melts and coalesces or that the molten metal forms a sheet and when the temperature of the ribbon falls to a temperature below the melting point of the metal during the flat glass forming method Leave a solid continuous layer at the surface of the.

Within the context of the present invention, metal means a material having essentially the electrical properties of a conductive type. It is a metal material based on at least two metals, for example in the form of intermetallic compounds, alloys or eutectic mixtures.

The metal according to the invention is advantageously based on at least one material included in the group comprising aluminum, zinc, tin and cadmium. It may optionally include silicon or other metals (particularly concentrations up to 15 at.%).

As a non-limiting preferred embodiment of this material, aluminum, aluminum-tin alloys, aluminum-zinc alloys, aluminum-silicon mixtures, in particular aluminum-silicon eutectics comprising 12 at.% Of silicon and having a melting point of approximately 575 ° C. Reference is made to the mixture.

In addition, continuous layer means a layer that can be deposited on the glass ribbon to cover most, but not most, of the surface. However, it may also comprise a layer which is deposited, for example, in the form of parallel stripes, and thus partially covers the surface of the glass in a planned and desired manner, for example for decorative purposes.

It may also include a layer that looks macroscopically continuous, but can only finely cover a portion of the glass ribbon.

Also within the context of the present invention, the surface of the ribbon means not only the pure glass surface, but also the surface of the glass selectively treated / covered with at least one coating given previously.

The present invention is well applied to glass ribbons in float lines. However, it is not limited to this, but may also be applied to non-continuous glass substrates such as glass ribbons, or glass plates, which are not manufactured from float lines.

The process according to the invention has a number of advantages, while within the invention the metal is used only in the solid state or in the liquid state, not in the gaseous state as in the French patent (FR 2,011,563). As a result, the realization of the method is facilitated because it is easier to control the distribution of powder or liquid than vapor on the glass surface. Moreover, this overcomes the problem of the limiting factor of metal vapor pressure, and thus a fairly high deposition rate can be obtained. This is a major advantage in making a layer having a relatively large thickness, in particular a thickness sufficient to convert glass into a mirror. This means that in a deposition operation on a float line in a float bath chamber, the glass must already be sterically stable and the space where deposition is performed is considerably less, compensating for low deposition rates due to long deposition times or long metal / glass contact times. Because there is no need to do.

Moreover, the method according to the invention comprises the melting operation of the metal powder or the sheeting operation of the molten metal in advance on the surface of the glass. Thus, regardless of whether this is in the solid or liquid state, or the gas state (known as CVD (chemical vapor deposition)), pyrolysis in the usual sense does not occur. This is because, in contrast, pyrolysis involves a chemical rebound step that decomposes the precursor of the derivative form of organometal on the contact surface with the hot glass.

This difference has a very positive effect on the properties of the layers obtained. The layer according to the invention tends to be more cohesive, denser and less coarse than the thermally decomposed layer because it is produced from the melting of the elemental metal. They also tend to crystallize better, because in the present invention crystallization occurs during solidification of the layer at a rate corresponding to the cooling rate of the glass ribbon along the path in the float line. Minimal partial crystallization of the thermally decomposed layer generally occurs more suddenly during the decomposition of the precursor and sometimes involves mechanical stress.

The layers according to the invention also tend to be less contaminated, since there is little risk of inclusion of impurities in the layer during formation, and in the case of pyrolysis layers, this is different, for example they are the decomposition of organic precursors in glass. A certain amount of residual carbon coming from.

In addition, these improvements result in layers with higher quality and longer durability. The denser the layer and the more sticky to the glass, the greater the ability to withstand corrosion or oxidation, especially in wet media. This has the advantage if the glass ribbon is subsequently cut into a substrate to be subjected to a heat treatment such as a bending operation and / or a tempering operation. Low surface roughness (roughness) also ensures good corrosion resistance and minimizes the haze effect due to a certain amount of diffuse reflection. Finally, a very low amount of absorbent particles in the form of carbon associated with higher purity, in particular a relatively high degree of crystallization, gives the layer according to the invention a very high light reflectivity, which is most necessary, among other things, in the manufacture of mirrors.

Thus, the possibility of industrial use of the method according to the invention does not cause a loss of performance of the reflective layer thus produced.

It is important that the deposition be carried out in an inert or reducing atmosphere so that the oxidation of the metal powder and the oxidation of the layer itself as it is formed before contacting the glass ribbon does not occur. Deposition can be performed in a float chamber, thus having the advantage of a controlled atmosphere of nitrogen and hydrogen mixtures. Optionally, deposition may be performed downstream of the float bath chamber, in particular in an essentially sealed box that selectively extends the chamber. This extension is described in particular in the French patent (FR-2,348,894).

Advantageously, deposition of the reflective layer is carried out when the glass ribbon is at a temperature above the melting point of the metal, thus this ensures that the metal particles reaching the glass are melted and that the molten metal is well dispersed at its surface.

The metal in powder form may contact the surface of the glass in two other embodiments.

The first embodiment sprays the metal powder in the form of a float in a carrier gas, inert or reducing to prevent oxidation, in particular using a dispersion nozzle. This dispersion nozzle may be a static nozzle, disposed on the glass almost across the travel axis, over all or a portion of the ribbon width. It can also be a moving nozzle that moves back and forth along an axis substantially transverse to the travel axis of the glass ribbon. In the case of depositing a layer consisting of a single metal such as aluminum, the powder consists of particles of the metal only. When the final layer is an alloy, the powder is preferably a mixture of each component powder of the final coating, and it is possible to adjust the ratio of the mixture as necessary or to use a powder prepared directly from the alloy.

The particle size (average diameter of the particles constituted) of the powder or mixture of powders is advantageously between 0.1 and 100 μm, in particular between 1.0 and 50 μm, such as between 5 and 10 μm. In this particle size range, the powder particles may be melted or coalesced on the glass in an optimal manner.

The second embodiment forms a metal on the glass ribbon in place from the at least one metal derivative, in powder form, in particular in the gaseous state, the decomposition of which into the metal by thermal activation and / or By allowing them to react in contact with each other. This is another way to prevent the metal formed in the inert or diminishing atmosphere present on the glass from oxidizing. Moreover, starting from natural materials in gaseous form, chemical vapor deposition (CVD) techniques can be used without all of the drawbacks described above, if any decomposition exists within the context of the present invention, it is in contact with the glass. This is because it occurs on the glass without this.

The powder thus formed preferably has the same particle size as previously mentioned.

The metal powder is preferably in situ from a metal derivative (or derivatives) selected from metal alkyl, metal hydroxides, or mixtures of metal hydroxides / metal alkyls synthesized by ammonia or amines, in particular in the case of aluminum by alanes. When the layer to be formed and in particular to be obtained consists of an alloy, a single form of precursor is selected or various forms of precursor are selected.

The decomposition temperature to the metal is between 50 and 600 ° C, in particular between 200 and 450 ° C. Therefore, it has been found that this temperature range does not match the temperature of the glass ribbon during the decomposition of the layer, i.e. unlike chemical vapor deposition, there is no correlation between the decomposition temperature of the selected metal derivative and the glass temperature upon deposition. Therefore, it is more free to optimize each of these independently of each other and to select the appropriate metal derivative (s).

Within the present invention, at least one additive that promotes controlled aggregation or growth of metal particles can be combined with the metal derivative. These additives help to adjust the powder particle size formed on the glass. Therefore, the metal derivative is advantageously inserted in the form of a gas on the glass ribbon using the device, the wall of the device defining a channel for guiding the resulting powder. The wall of this cavity is preferably almost vertical, possibly in the form of a tip spread, or in contrast to a glass ribbon, in contrast, with a suitable thermal gradient over a minimum portion of its height. Is done. Thermal increase and decrease means precise control of the temperature at which a relatively gradual method is well chosen to increase towards the glass. Adjusting this increase or decrease of temperature results in the decomposition of the metal derivative into metal particles on the one hand and satisfactory particle size on the other hand, in particular from 5 to 10 μm, as in the first embodiment according to the invention. Provides control of the position in the moment and in the dynamic, where good growth of the metal particles takes place.

In a preferred variant, the method injects metal derivatives on top of the device cavities and extracts the waste resulting from their decomposition by means of vacuum means configured in the walls of the cavities, the extraction results in the formation of metal powder and sufficient particle size. It happens at or near the level to reach. In this method, for example, the waste is extracted before contact with the glass or included in the metal particles by chemical reaction, for example to form carbides or nitrides of the metal, and the powder itself simply falls on the glass by gravity. A facility for injecting inert or reducing gas at at least one point of the cavity can be provided, which makes it possible to avoid agglomeration of the metal powder on the wall of the cavity.

Moreover, the cavity can be designed to be filled with this atmosphere since it is in an inert and / or reducing atmosphere at least partially present on the glass. If a gaseous metal derivative is inserted as a suspension in the carrier gas, the carrier gas is of course selected to have inert and / or reducing properties.

Regardless of whether the metal powder is sprayed directly or by using a metal derivative, in the present invention, under the influence of heat released at a short distance with the glass ribbon, it melts or dissolves in contact with or near the glass directly above the glass. I need to understand that. Therefore, the powder falls on the glass in the form of showers of droplets.

Another possibility according to the invention is the use of already molten metal, which is sprayed onto the surface of the glass using a stationary dispersion nozzle disposed on the glass across the running axis of the glass, not the metal powder or the metal derivative in gaseous state. The dispersion nozzle ejects a curtain of molten metal onto the glass. Alternatively, a moving nozzle in the form of a spray-gun may be used to move back and forth over the glass.

As mentioned above, the reflective layer according to the invention has two very advantageous properties.

On the one hand they are denser than the layers obtained by pyrolysis or fortiori, for example by vacuum deposition techniques in the form of sputtering or evaporation. Especially for aluminum layers this density is at least 80% of the theoretical density of the metal. Even 90-95%. Moreover, this density allows for greater light reflectivity to be obtained for a given thickness (it should be noted that these densities can be measured indirectly using the electron density measured by the X-ray reflectometer).

On the other hand, these layers contain little or very small amounts of impurities, particularly carbon-, oxygen- or nitrogen-type impurities, which tend to increase the absorption or transmission of the layer which worsens the light reflectance. Thus, these low amounts of impurities conform to high densities in order to obtain maximum mirror effect for a given thickness. The maximum impurity level varies slightly depending on which method is selected according to the present invention. The layer can be extremely pure if it starts with a powder or melted form of material that will constitute the layer, which does not involve at least partially organic decomposition of the precursor. Thus, it generally contains at most 1 at.% Of oxygen or carbon impurities, and these impurities may be included in the layer during layer formation, such as by air pollution or by being present in the starting powder. In general, the amount of impurities is less than 1 at.% And remains below the detectable threshold of the measuring device, in this case the scanning electron microprobe. In contrast, if disclosed with a precursor in the form of at least partially organic metal derivatives, the reflecting layer remains very pure, but the amount of impurities is likely to increase to 2-3 at.%, More than before. These may be carbon, oxygen or nitrogen, especially when initiated with an alan-like mixture.

Whatever the way the metal is in contact with the glass, it may be advantageous to treat the glass surface prior to properly depositing the metal layer. There are at least two reasons for carrying out such pretreatment, one of which is to facilitate wet / adhesion of the layer to the glass. The other is to inhibit similar reactions at the glass / metal interface intended to form metal oxides corresponding to the metals and silicon from the metals and silicon oxides contained in the glass.

Without actual chemical reactions, it is only surface sensitization that causes gaseous by-products at the contact surface with the glass, with minimal partial gas adsorption by the glass surface. The gas can be for example titanium tetrachloride (TiCl ₄ ).

However, the pretreatment may involve the deposition of a minimum of so-called intermediate layers prior to the deposition of the layer. The intermediate layer (s) can be selected well based on at least one of the materials included in the following groups. These groups include silicon, oxides such as oxides of silicon, oxycarbide or oxynitride, titanium oxide (TiO ₂ ), cerium oxide, aluminum oxide (Al ₂ O ₃ ), and oxidation Nitrides such as zirconium (ZrO ₂ ), zinc oxide (ZnO), aluminum nitride (AlN), silicon nitride (Si ₃ N ₄ ), titanium nitride (TiN) and zirconium nitride, boron oxide, yttrium oxide, Magnesium oxide, mixed oxides of Al and Si, aluminum oxide to which fluorine is added, and magnesium fluoride (MgF ₂ ). Carbide may also be included. Their deposition is preferably performed by chemical vapor deposition (CVD). This intermediate layer preferably has a maximum refractive index of 1.8 and light absorption of 3% or less. The optical thickness of the interlayer can be between 40 and 120 nm, with 70 to 100 nm being preferred. The chemical role of this intermediate layer is to protect the thin metal reflective layer after the manufacture of the mirror in the float bath chamber, or after subsequent heat treatment of the mirror, or during normal use of the mirror, for example in a bathroom.

Once the reflective metal layer has been deposited on the ribbon of float glass, post-treatment should be considered to protect it from oxidation. The most effective method in the aftertreatment is to cover the ribbon with a minimum of so-called additive layers when the ribbon is in an inert or reducing atmosphere in which the deposition of the reflective layer is carried out.

The additional layer (s) may be selected based on a nitride such as aluminum nitride, silicon nitride or titanium nitride.

However, they may also be based on oxide (s) comprising at least one oxide included in the following group. These groups include titanium oxide (TiO ₂ ), tin oxide (SnO ₂ ), zirconium oxide (ZrO ₂ ), zinc oxide, niobium oxide, tungsten oxide, antimony oxide, bismuth oxide, tantalum oxide or yttrium oxide, aluminum nitride or nitride Composed of silicon, or of fluorinated tin oxide or carbon such as diamond (DLC), aluminum oxide (Al ₂ O ₃ ), consisting of silicon oxide, oxycarbide and / or oxynitride, or vanadium oxide And so on. In the latter case, provision may be provided for depositing a sacrificial silicon layer between the metal layer and the oxide layer (s), in order to further limit any contact with the mixture comprising the oxygen containing metal, The silicon layer is sufficient to avoid metal / oxide contact, but thin enough that the stack does not absorb light (this also applies when an intermediate layer of pure silicon is selected, and it is advantageous to limit the thickness to several nm). . Deposition of additional layer (s) is preferably performed by chemical vapor deposition.

The additional layer covering the reflective metal layer may have a chemical synthetic slope and / or refractive index slope through its thickness. This can be a slope of increase or decrease, in particular by depositing a material having a low refractive index (e.g., between 1.45 and 1.60), and while the layer is formed, the low refractive index is especially within a material having a high refractive index of at least two. It becomes large and can be configured in reverse to the above. The chemical synthetic slope can advantageously impart two properties on a single layer, sacrificing one for the other, as it considers the coalescing of the layers to be in contact with the layer and also as mechanical / chemical durability. Optimize them at the same time without processing.

This exponential slope and / or this chemical synthetic slope is a dispersion nozzle with two injection slots (one for each gaseous precursor needed to obtain two materials of low exponent and high exponent). Can be obtained by chemical vapor deposition, also by configuring them so that partial and gradual mixing between the two gas streams emanating from the two injection slots is caused along the glass.

As a preferred additional layer having a synthetic gradient, a layer based on silicon oxide is used, and the gradient gradually increases in titanium oxide. When a thin layer of sacrificial silicon is deposited on the reflective layer, good adhesion of Si / SiO ₂ or Si / SiO _x C _y is obtained on the reflective layer side, and the lamination is completed by titanium oxide. If done well, it exhibits very advantageous antifouling and moisture resistant properties in addition to known photocatalytic properties.

The metal reflective layer may be chosen to cover a series of layers with high and low indices, such as SiO ₂ / TiO ₂ .

Each additional layer preferably has a geometric thickness of at least 10 nm, between 20 and 150 nm, in particular between 50 and 120 nm.

Even more generally, in consideration of the properties of the material constituting the outer complementary intermediate layer and the inner additional layer, they are selected so that light interference with the reflective layer is as small as possible.

They are therefore preferably chosen to be based on materials transparent or mixtures of these materials at wavelengths in the visible light.

Thus, they may include oxide (s), oxycarbide (s) or oxynitride (s), in particular magnesium (Mg), of elements of groups IIA, IIIB, IV, IIIA and IVA and of the lanthanide series elements in the periodic table. Calcium (Ca), Yttrium (Y), Titanium (Ti), Zirconium (Zr), Hafnium (Hf), Cerium (Ce) (CeO ₂ or Ce ₂ O ₃ ), Aluminum (Al), Silicon (Si) or Tin Based on oxides, oxidized carbides and oxynitrides of (Sn). As the transparent oxide, a doped metal oxide such as fluorine-added tin oxide (F: SnO ₂ ) may be used.

Of all these compounds, for example, per mole of oxygen at a high temperature below the temperature of the metal on which the reflective layer is formed, in particular on the order of 500 to 600 ° C., with reference to a chart showing the free enthalpy of the oxide composition known as the Ellinghan diagram as a function of temperature. It is advantageous to select an oxide with a standard free enthalpy (ΔG °) of the configuration. Thus, oxidation of the reflective layer metal does not occur thermodynamically, so if the deposition of the reflective layer is carried out on a ribbon of float glass, the oxidation or deterioration of the reflective layer is limited as much as possible at high temperatures during the deposition, 450 to 700 ° C.

Thus, when the reflective layer is selected to be based on aluminum, it is advantageous to select a layer based on aluminum oxide, zirconium oxide, magnesium oxide or lanthanum oxide as the outer and / or inner complementary layer. These oxide layers are specially deposited using pyrolysis techniques or chemical vapor deposition in the solid or liquid state. If deposition is performed in a float bath chamber, chemical vapor deposition (CVD) will be used. Outside the float chamber, CVD, solid state pyrolysis or liquid state pyrolysis techniques can be used. Thus, by chemical vapor deposition, an oxide layer such as silicon oxide or silicon oxide carbide from a gaseous precursor in the form of silane or ethylene can be deposited, as described in EP-0,518,755. have. The TiO ₂ layer can be deposited by CVD from an alkaline oxide such as titanium tetraisopropylate, and the tin oxide is butyltin trichloride or dibutyltin diacetate by CVD. diacetate). The aluminum oxide layer can be deposited from an organometallic precursor such as aluminum acetylacetonate or hexafluoroacetonate by liquid phase pyrolysis or chemical vapor deposition.

The complementary transparent layer can be selected to be based on a nitride or mixture of nitrides of at least one of the Group IIIA elements of the periodic table, such as aluminum nitride (AlN), gallium nitride (GaN _x ) or boron nitride (BN _x ). The AlN layer may be deposited from an aluminum alkyl or hydroxide precursor combined with a precursor containing nitrogen in the form of ammonia and / or amine, for example by CVD. As the transparent nitride, silicon nitride (Si ₃ N ₄ ) can be used. This is because silicon nitride (Si ₃ N ₄ ) is a very effective material for protecting the reflective layer from oxidation. It may be deposited from silane and ammonia and / or amines by CVD.

At least one of the complementary layers, in particular the outer layer, may be selected to be based on a transparent material in the form of diamond or diamond-like carbon (DLC), which material has a high hardness, thus making the lamination below This is necessary (it also holds to some extent for titanium oxide) because it protects very effectively from abrasion.

At least one of the inner and outer complementary layers is not based on a material that is transparent to visible light, but in contrast may be selected to be based on material (s) that absorb some of the visible light, which material (s) may comprise a reflective layer. It is different from what can be configured. In view of the above-mentioned transparent materials, it is preferable to limit the complementary layer of this form to a small thickness, especially 1 to 8 nm, in order to avoid any optical interference. Nitrides of transition metals such as nitrides or carbon nitrides of tungsten (W), zirconium (Zr), hafnium (Hf), niobium (Nb) and titanium (Ti) may be used. Semiconductor materials such as silicon may also be used.

In this case, the materials are selected according to the affinity for the material of the glass and / or reflective layer and the chemical inertness to the reflective layer. Thus, when the reflective layer is composed of a metal, it is advantageous to select an interlayer of the Si thin film, which is an effective barrier against diffusion of alkyl and coral from the glass and can serve as an accelerator of glass / metal adhesion. Silicon may be deposited by CVD from SiH ₄ .

At least one of the complementary layers may have a chemical synthetic slope through its thickness, thereby allowing two properties to be provided on a single layer.

Thus, this is based on the progressively increasing SiO ₂ or SiO _x C _y in silicon, or if the reflective layer is composed of aluminum, then gradually increasing SiO ₂ or SiO _x C in the oxide of the metal of the reflective layer, such as Al ₂ O ₃ It can be an inner complementary layer based on _y . For the improved affinity of the latter (aluminum reflective layer) in contact with the glass and with the reflective layer, the role of promoting adhesion and reducing mechanical stress in the inner layer is thus optimized.

The outer complementary layer can have a gradually increasing chemical synthetic slope in titanium oxide based on the metal oxide or SiO _x C _y of a reflective layer such as Al ₂ O ₃ , France, filed September 15, 1995 As described in the patent (FR95 / 10839), the Al ₂ O ₃ type oxide has good affinity and high chemical inertness to aluminum when this type of material constitutes a reflective layer, and TiO ₂ itself is a laminating machine It is possible to improve the durability and to impart favorable moisture / pollution prevention properties to the lamination.

These chemical synthesis gradients are also produced by chemical vapor deposition, using a dispersion nozzle with two injection slots, one of which is for each gaseous precursor needed to obtain two materials. Thus, by configuring the two injection nozzles for actual and gradual mixing between two gas streams emanating from the two injection nozzles, for example, as described in the PCT patent (PCT / FR96 / 01073) filed July 10, 1996 As can be obtained.

The inner and outer complementary layers generally have a geometric thickness between 1 and 200 nm, in particular between 30 and 160 nm when transparent and between 1 and 5 nm when absorbent.

In fact, the thickness of the complementary layers varies according to a number of parameters, including the properties of these layers, the properties of the reflective layer, and the attack (environment) form to which the stack is exposed. Therefore, during high temperature deposition of the reflective layer, in order to maintain its properties, it is desirable to make the reflective layer chemically independent using the inner and outer complement layers. Furthermore, if the glass substrate must be subjected to a subsequent heat treatment in the form of annealing, bending or tempering, these layers once again serve a protective role, and in the latter case these are more than if the substrate does not have to perform this post deposition treatment. It is advantageous to form a thick layer.

Embodiments of the laminate according to the present invention are as follows.

TiN or AlN / Al / AlN

AlN / Al / SiO _x C _y

Al / SiO _x C _y

SiO _x C _y / Al / SiO _x C _y

Si / Al / SiO _x C _y

Al ₂ O ₃ / Al / Al ₂ O ₃

The invention also relates to glass for the fabrication of antifouling and / or moisture resistant mirrors or panes, as previously described and whose outer layers consist of TiO ₂ (or terminated with TiO ₂ in the case of layers with synthetic slopes). Specifying the application of the substrate, the outer complementary layer for the manufacture of wear resistant mirrors is harder than the reflective layer, and is in particular based on diamond or diamond-like carbon. The glass substrates of the present invention are also intended for application in the manufacture of heated windows, which are heated by means of a current flowing through a reflective layer of appropriate thickness.

The subject matter of the present invention is any other product which can obtain a low level (actual zero or visually zero level) of all the products obtained, in particular using previously defined methods, or similar properties, in particular the density and impurities in the reflective layer The method relates to a product obtained after cutting a ribbon of float glass.

These products can be applied in two applications. First, they can be used as glazing for building and automobiles, and metal reflective layers made of aluminum provide sun protection for these glazing. In this case, the thickness of the reflective layer is limited to 30 nm or less, so as to maintain a sufficient level of light transmission.

Secondly they can be used as mirrors. In this case, it is necessary to obtain very high light reflectivity, and in this case it is therefore preferable to use a metal layer having a thickness of at least 30 nm.

Even more generally, glass substrates coated according to the present invention have a wide variety of applications, including floor mirrors in photovoltaic cells, floor mirrors in washbasins, mirrors of reversing photocopiers, and sun protection panes for buildings or any automobile (low transmittance or Reflective or translucent, including sun-proof forms), electromagnetic radiation-resistant windows (radar or radio waves), rearview mirrors, furniture elements based on glass, walls of containers in aquarium or pool form as interior separation and mirrors inside decorative glass Can be used for mirrors. Substrates according to the invention can use reflecting layers as conducting electrodes, for example in electrochemically active panes, such as electrochromic or viologenic panes, liquid crystals or optical-valve panes. have.

The present invention also relates to a method for producing a laminate coated on a glass substrate by high temperature deposition of a reflective layer from molten metal powder according to the D.P.M treatment previously described. The complementary layer (s) are preferably deposited by chemical vapor deposition or pyrolytic deposition in the liquid or solid state.

Preferred manufacturing methods deposit all layers on a ribbon of float glass at high temperature by good deposition of at least the first two layers in the float bath chamber. Thus, the deposition significantly reduces time and manufacturing costs, as well as a high temperature deposited layer, as compared to techniques in which deposition takes place in subsequent steps, including immersion in sputtering, sol-gel or silver plating baths. Solidity which is a characteristic of and substrate adhesiveness is obtained.

A preferred embodiment of the article according to the invention can be a glass substrate comprising the following sequence, ie irrespective of mirror or pane, ie

Aluminum / aluminum nitride, otherwise,

Aluminum / silicon / oxide, or

Aluminum / aluminum nitride.

Other details and advantageous properties emerge from the following description of non-limiting embodiments in connection with the following figures.

Both FIG. 1 and FIG. 2 are schematic representations without careful consideration of proportions for ease of understanding.

The following example is produced on a 4 mm thick float glass ribbon, soda-lime silica glass, which is cut once and obtainable from Saint-Govin Vitrajuse under the name Planilux.

This may equally be a particularly transparent glass or a whole tinted glass, such as a once cut glass product, available from Saint-Govin Vitrajusa in the name of Diamant or Parsol.

After cutting, a glass substrate as shown in Fig. 1 is obtained, in which a lamination is provided in the following manner, wherein the substrate 1 is coated with an optional first layer 2 of silicon called an intermediate layer. This intermediate layer itself is covered with a metal reflective layer 3. The metal reflective layer is covered with an optional additional layer 4 based on silicon, on which a second additional layer 5 is deposited.

In all examples, the reflective layer 3 consists of aluminum and is deposited on the glass ribbon by the method described with reference to FIG. 2.

As shown in FIG. 2, a portion of the glass ribbon 10 lies in a float-bath chamber, the ribbon 10 comprising a tin chamber and filled with a controlled atmosphere composed of a mixture of nitrogen and hydrogen. Float) on the surface of the molten tin chamber 11. The glass is drawn from a glass-melting furnace, not shown, to the left of FIG. 2, to form a ribbon extracted from the bath at a constant speed in the direction of the arrow by extraction means mounted on the outlet of the bath on the right side of the drawing. It runs above the tin chamber 11 and is dispersed there.

In the region of the float bath where the glass obtains its dimensional stability, mounted on a ribbon 10 having a width of approximately 3.30 m is the apparatus 12 disposed entirely inside the float bath chamber. This device is in the form of a gas dispersion nozzle over the gas ribbon 10 and is arranged over the entire width to cross the travel axis. The device 12 defines a cavity 15 in a substantially parallel hexagonal form by the side inner wall 14 and the upper inner wall 14 ′, and the wall 14 of the cavity across the glass axis is directed to the glass. Nearly vertical or slightly concentrated or spread out. The ends of these walls in the lower part are very close to the surface of the glass, for example a distance of 20 mm or less from the surface of the glass. These walls are formed with the following various openings,

Openings in the top wall 14 ′ and / or in the side wall 14 provide a passage for the N ₂ / H ₂ gas mixture in the float bath chamber in the cavity 15,

A plurality of openings configured at the top wall 14 ′ and / or on top of the wall 14, as injectors (not shown) from which an inlet tube 17 is connected, connected to a means for supplying a gas mixture x, Arranged in a constant line above the full width of 15,

A plurality of openings 18 configured on at least one transverse side wall 14, in particular at a height of approximately 1/4 or 3/4 of the wall, from which a gas extraction tube is connected to the extraction means not shown. Come out,

A plurality of openings 18 formed in at least one side wall of the cavity 15, in particular at the height of the first third of the cavity, from which N ₂ / similar or identical to the mixed gas present in the float chamber A gas inlet tube 20 is connected which is connected to a means not shown for supplying the H ₂ gas mixture.

Arranged in the inner wall 14, 14 ′ and outer wall 21 of the device 12 in combination with means, in particular cooling means, capable of controlling and regulating the temperature of the cavity 15 through the overall height h Heat / heating means, the operation of which is combined with a temperature measurement inside the cavity and their temperature is regularly measured by a suitable detector, so as to obtain an increasing temperature gradient towards the glass ribbon 10, the overall height h A temperature profile for) is generated by manual adjustment of the thermal / cooling means or by electronic / computer based automatic control, the temperature gradient starting at approximately 20 to 100 ° C. at the top near the opening 16 and at 600 near the glass. Increases up to ℃.

Apparatus 12 operates in the following manner: Vapor from an aluminum derivative of a suspension in an inert gas, such as nitrogen (mixed gas x described above), is continuously injected through opening 16. In particular such derivatives may be Al (CH ₃ ) ₃ , Al (C ₂ H ₅ ) ₃ , AlH ₃ (NH ₃ ) or AlH ₃ (amine).

This is, in particular, dimethylmonoethylamine alane, a hydroxide stabilized by amines, which decomposes to metallic aluminum at approximately 180 to 200 ° C., with the formula AlH ₃ (N (C ₂ H ₅ ) (CH ₃ ) ₂ )to be.

In the scanning region in the cavity, the temperature is approximately 40 ° C. and the mixed gas x is dispersed into the cavity, almost perpendicular to the plane defined by the glass ribbon 10. As the temperature in the cavity increases gradually as it approaches glass, alan decomposes to form powdered aluminum 22 in region h ₁ in cavity 15, which is located approximately midway above the cavity. The aluminum particles simply fall on the contact surface with the glass under gravity, while the effluent resulting from the decomposition of the alan is extracted through the opening 18 in the powder forming region h ₁ . In order to obtain powder particles of particularly large diameter, the parameters of the decomposition reaction of alan are adjusted so that the effluent can be extracted without dropping the formed powder 22 into the extraction tube, and the aluminum particles according to an undesired chemical mechanism The reaction of the effluent at high temperatures to is avoided.

The powder reaches a glass ribbon which is at a temperature of 660 to 700 ° C., in particular approximately 680 ° C., which is the maximum temperature at which the glass is stericly stable (700-750 ° C.) and the melting point of aluminum (approximately 650 to 660 ° C.) Is the temperature between. In order to leave a continuous film of molten aluminum that gradually solidifies as the temperature of the glass decreases below the melting point of aluminum, the aluminum particles in contact with the glass melt instantly and droplets coalesce.

The final thickness of the aluminum layer thus deposited can be varied as desired by adjusting various deposition parameters, in particular the concentration of alan in the mixed gas x, the flow rate of the mixed gas, and the like.

Moreover, the H ₂ / N ₂ mixed gas is injected through the opening 19 so that the mixed gas is injected toward the top of the cavity 15 at approximately tangent to the side wall 14, in this method, aluminum powder along the wall. Accumulation of cavities is avoided, thus contamination of the cavity 15 is reduced, and dropping of particles instantly accumulated on a point on the ribbon, which can degrade the quality of the coating, is prevented.

Referring to FIG. 1, an aluminum layer 3 is thus deposited using the apparatus 12 described above. Prior to this deposition, the thin film 2 of pure silicon has a device 12 when the glass ribbon has already obtained dimensional stability, i.e., at approximately 700 ° C, as described, for example, in French patent (FR-2,382,511). Is deposited from the silane in a known manner by CVD, using a nozzle arranged on top immediately before.

Before the glass ribbon provided with the silicon interlayer 2 and the aluminum reflective layer 3 leaves the float bath chamber, one or more additional layers are deposited, the order of which is explained in detail in the following example. These can be deposited from aluminum alkyl or hydroxide precursors with ammonia or amines, from aluminum nitride layers deposited by known methods by CVD, and / or from silanes or ethylene to CVD, as described in European Patent (EP-0,518,755). Known by CVD from an oxide layer, such as silicon oxide or silicon oxide carbide, otherwise gaseous precursors such as butyltin trichloride or dibutyltin diacetate, which are deposited by known methods Titanium oxide deposited in a known manner by CVD from a precursor in the gaseous state, such as titanium alkaline oxide in the form of titanium-tetraisopropylate, otherwise titanium-tetraisopropylate.

Instead of, or in combination with, the SnO ₂ or TiO ₂ oxide layer, it is also possible to use a silicon oxide layer deposited by CVD from a gaseous precursor such as tetraethoxysilane. Aluminum oxide layers deposited by CVD from gaseous precursors such as aluminum acetylacetonate or hexafluoroacetonate may also be used. The vanadium oxide layer may also be deposited by CVD from a gaseous precursor in the form of a vanadium alkaline oxide such as vanadium tetraethylate, or in the form of a halide such as VCl ₅ , or an oxidized carbide form such as VOCl _3. May be selected.

Instead of, or in combination with, the aluminum nitride layer, a silicon nitride layer may be used which can be obtained by CVD from a gas mixture comprising silane and ammonia and / or amines.

In the case where it is desired to deposit the oxide layer 5 rather than the nitride layer on the aluminum layer 3, a thin film silicon layer 3 deposited by CVD is inserted like the layer 1 described above.

Thus, all depositions in the following examples, in a float chamber, i.e. strictly in a non-oxidizing atmosphere, the glass is at a temperature between approximately 750-700 ° C. for the deposition of the first silicon layer, When carried out at a temperature of at least 580 to 590 ° C. for deposition, the glass ribbon generally leaves the float bath chamber at a temperature of approximately 580 ° C.

Example 1

Using the technique described above, the following layers in the following order are deposited on the surface of the glass ribbon 10 (indicated in nanometers in thickness below each layer).

Glass ⁽¹⁾ / Al ⁽³⁾ / AlN ⁽⁵⁾

50 nm 130 nm

Example 2

The order is as follows:

Glass ⁽¹⁾ / Al ⁽³⁾ / (AlN / TiO ₂ ) ⁽⁵⁾

50 nm 60 nm / 50 nm

Example 3

Glass ⁽¹⁾ / Si ⁽²⁾ / Al ⁽³⁾ / Si ⁽⁴⁾ / (SiO _x C _y / TiO ₂ ) ⁽⁵⁾

2 nm 50 nm 4 nm 70 nm / 60 nm

Here, the refractive index of SiO _x C _y / is set to approximately 1.55.

Example 4

The order is as follows:

Glass ⁽¹⁾ / Al ⁽³⁾ / (AlN / TiO ₂ ) ⁽⁵⁾

50 nm 60 nm / 50 nm

Here, the refractive index of aluminum nitride is 1.85.

Example 5

The order is as follows:

Glass ⁽¹⁾ / Al ⁽³⁾ / Si ⁽⁴⁾ / SnO ₂ ⁽⁵⁾

50 nm 4nm 120nm

Example 6

The order is as follows:

Glass ⁽¹⁾ / Al ⁽³⁾ / Si ⁽⁴⁾ / (SiO ₂ / TiO ₂ Gradient Layer) ⁽⁵⁾

50 nm 5nm 120nm

The SiO ₂ / TiO ₂ gradient layer is a layer obtained by CVD and includes at least 80% weight of SiO ₂ at the interface with the underlying silicon layer 4 and at least 80% weight of TiO ₂ at the interface with air. To have a composite. This is obtained from the previously mentioned silicon oxide and titanium oxide precursor according to the French patent (FR-95 / 08421: July 12, 1995), in particular according to the technique described in Example 9 of this patent.

Next, the glass ribbon in each of these six examples is cut and the light reflectance R _L is measured as a percentage for the D ₆₅ light source in each of the six glass plates to obtain the following results.

Yes R _L Example 1 92% Example 2 92% Example 3 96% Example 4 95% Example 5 92% Example 6 95%

In conclusion, each of these six plates can advantageously be used as a so-called face 1 mirror, ie a mirror in which the viewer looks at the glass substrate on the side provided with the reflective layer 3.

By suitably adapting the order of the so-called intermediate layer 2 and / or the additional layers 4 and 5, the so-called face 2 mirror, ie the viewer looks at the substrate from the opposite side provided with the reflective layer 3 Of course, you can make a mirror.

Moreover, a substrate made in this way but provided with a slightly thin aluminum layer 3, for example 10-20 nm, can be used very satisfactorily as a sun protection windowpane.

However, it is important to protect the aluminum layer as much as possible during oxidation or heat treatment in the form of bending or tempering, as well as leaving the float bath chamber from oxidation on the production line. The additional layer 5 according to the invention effectively achieves this protection. The silicon interlayer 2 is optional, which facilitates the adhesion of aluminum to the glass and prevents the reaction to produce aluminum at the glass / aluminum interface. However, by passing TiCl ₄ over the surface of the glass prior to gas treatment, such as the deposition of an aluminum layer, this can be omitted or replaced.

The silicon layer 4 on the aluminum layer is also optional, which prevents the aluminum layer from oxidizing during the deposition of the next oxide layer.

For optical reasons, in particular to increase the light reflectivity, an additional layer, in particular an oxide layer, may be deposited, for example, on the other side of the glass ribbon in a subsequent step.

Thus, the present invention has developed a continuous production of mirror or sun protection glass plates on a float line, which production is quite advantageous in production and cost. The aluminum layer thus deposited is of high quality, especially very dense, very pure (without contamination), and particularly strong on glass (or the layer directly below).

Claims (38)

In a method of continuously continuously depositing a reflective layer 3 based on a metal whose melting point is below the temperature at which the glass ribbon obtains dimensional stability, on a glass ribbon 10 of a float line, In a controlled atmosphere of inertness and reduction, when the glass ribbon 10 has already obtained its dimensional stability, the deposition is carried out by contacting the surface of the ribbon with metal 22 in powder or molten form. The temperature of the ribbon during contact is solid when the powder melts and coalesces on the surface of the ribbon or the molten metal forms a sheet such that the temperature of the ribbon is below the melting point of the metal. And to leave behind a continuous layer of layers. 2. The method of claim 1, wherein the metal is based on a single metal or based on a compound, metal alloy or eutectic compound of an intermediate metal. 3. The method of claim 1 or 2, wherein the metal is based on at least one of metals included in the group comprising aluminum, zinc, tin, cadmium, and optionally silicon. 4. The method of any one of claims 1 to 3, wherein the deposition is performed in a float bath chamber. The continuous deposition of a reflective layer as claimed in claim 1, wherein the deposition is carried out downstream of the float bath chamber, in particular in an essentially sealed box extending the chamber. Way. 6. The method of claim 1, wherein the deposition is performed when the glass is at a temperature above the melting point of the metal. 7. The dispensing nozzle of claim 6, wherein the contact of the metal in powder form with the surface of the glass is arranged on the glass ribbon and across the travel axis, the dispersing nozzle capable of dispersing the powder over the entire width of the ribbon. And dispersing the powder in suspended matter in an inert or reducing carrier gas, thereby continuously depositing the reflective layer. Method according to claim 7, wherein a powder particle size of between 0.1 and 100 μm, in particular between 1.0 and 50 μm, is selected. 5. The reflective layer according to claim 4, wherein the metal is produced from metal derivatives, especially in gaseous state, on the glass ribbon, and the decomposition of the metal derivatives to metals is caused by thermal activation and brings them into contact with each other. Method of depositing continuously. 10. The reflective layer of claim 9, wherein the derivative is selected from metal alkyls, metal hydroxides, ammonia or mixed metal hydroxides / metal alkyl compounds mixed by primary, secondary or tertiary amines. By deposition. Method according to claim 9 or 10, characterized in that the derivative decomposes into metal at temperatures between 50 and 600 ° C, in particular between 100 and 450 ° C. 12. The method of any of claims 9 to 11, wherein at least one additive that promotes aggregation or growth of the metal particles is combined with the metal derivative (s). The metal derivative (s) according to claim 9, wherein the metal derivative (s) is injected onto the glass ribbon 10 in gaseous state using an apparatus 12 comprising a cavity 15. The cavity wall (14, 14 ') defines a channel for guiding the powder (22) produced by the derivative towards the glass ribbon (10). 14. The wall (14) of the cavity (15) is substantially vertical and can be focused or widened towards the glass ribbon (10), Thermal gradient is generated for at least a portion of the height (h) of the cavity. 15. The method according to claim 13 or 14, wherein the metal derivative (s) is injected into the upper portion 16 of the cavity 15, The effluent resulting from the decomposition of the derivative is extracted in the wall 14 of the cavity 15 by side extraction means formed at or near the level at which the metal powder is formed and reaches a sufficient particle size. And continuously depositing a reflective layer. Method according to one of claims 13 to 15, characterized in that an inert or reducing gas is injected at at least one point (19) in the cavity (15). 17. The method of any one of claims 7 to 16, wherein the metal powder is dissolved on or near the glass ribbon (10). 7. The molten metal according to any one of the preceding claims, wherein the molten metal is in particular by using a static dispersion nozzle which ejects a curtain of molten metal onto the ribbon across the travel axis, or transverse to the travel axis of the ribbon. Using a moving nozzle to move around, spraying towards the glass ribbon. 19. The method according to any one of the preceding claims, wherein at least prior to the deposition of the metal-based reflective layer 3, in particular by contact / absorption of steam in the form of TiCl ₄ , or especially made of silicon (Si) or oxide. By depositing one interlayer, the surface of the glass ribbon is treated, the oxide being aluminum oxide (Al ₂ O ₃ ), oxide of silicon, oxynitride or oxycarbide (SiO ₂ , SiON or SiOC), zirconium oxide (ZrO ₂ ), cerium oxide, titanium oxide (TiO ₂ ), zinc oxide (ZnO), boron oxide, yttrium oxide, magnesium oxide, mixed oxides of Al or Si consisting of aluminum oxide or magnesium fluoride, or nitriding A mixed oxide of Al or Si consisting of a nitride such as aluminum (AlN), silicon nitride (Si ₃ N ₄ ), titanium nitride, zirconium nitride or carbide, wherein the intermediate layer is, for example, by chemical vapor deposition And depositing the reflective layer. 20. The metal-based reflective layer (3) according to any one of claims 1 to 19 is oxidized when the glass ribbon is in an inert and / or reducible controlled atmosphere in which the deposition of the reflective layer is carried out. A method of continuously depositing a reflective layer, characterized in that it is covered with at least one additional layer (5) to protect the reflective layer from. 21. The method of claim 20, wherein the selected additional layer (s) is based on a nitride such as aluminum nitride, silicon nitride or titanium nitride. 21. The selected additional layer (s) optionally deposited on the thin silicon sacrificial layer (4) is based on oxide (s), which oxides are titanium oxide (TiO). ₂ ), tin oxide (SnO ₂ ), zirconium oxide (ZrO ₂ ), oxides, oxides and / or oxynitrides of silicon (SiO ₂ , SiOC or SiON), aluminum oxide (Al ₂ O ₃ ), vanadium oxide, oxide Comprising tantalum oxide or yttrium oxide, consisting of tin, niobium oxide, tungsten oxide, antimony oxide, bismuth oxide, aluminum nitride or silicon nitride, fluorine-added oxide, or carbon-like diamond Continuously depositing a reflective layer. 21. The method according to claim 19 or 20, wherein the reflective layer 3 is added with a synthetic or refractive index gradient through its thickness, in particular by depositing a material, such as silicon oxide, which gradually increases in the material, such as titanium oxide. Method for continuously depositing a reflective layer, characterized in that it is covered with a conventional layer (5). 20. The method of claim 19 according to any one of claim 21, wherein the reflective layer 3 is a reflective layer, characterized in that the for example covered with a low index and the at least one sequence of high index, such as SiO ₂ / TiO ₂ in a row How to deposit. 25. The method of any one of claims 1 to 24, wherein the glass ribbon of the float line is replaced by a glass ribbon or a discontinuous glass substrate that does not come from a float line such as a glass plate. Way. In the glazing 1 obtained by cutting the coated float glass ribbon 10 according to the method according to any one of claims 1 to 25, According to the purpose of sun protection, a window pane, characterized in that an aluminum reflecting layer (3) having a thickness of 30 nm or less is provided. In the mirror 1 obtained by cutting the coated float ribbon 10 according to the method according to any one of claims 1 to 25, A mirror, characterized in that an aluminum reflecting layer (3) having a thickness of at least 30 nm is provided. The glazing 1 according to claim 26 or the mirror according to claim 27, in which a sequence of aluminum / SiOC or aluminum / AlN or aluminum / TiN or aluminum / Si / oxide is provided. How to. At least one reflective layer based on a metal in the form of a metal, alloy or eutectic compound of the intermediate metal compound, in particular based on at least one metal comprising aluminum, zinc, tin and cadmium, and optionally also included in the group comprising silicon In the glass substrate 1 provided with (3), For the reflective layer 3, an outer complementary layer 4 and / or an inner complementary layer 2 are provided on the substrate 1, the complementary layer (s) being chemical and / or mechanical. There is a glass substrate (1), characterized in that for ensuring durability. 30. The method of claim 29, wherein the inner complementary layer 2 and / or the outer complementary layer 4 is transparent at wavelengths in visible light and is Mg, Ca, Y, Ti, Zr, Hf, Ce, Al. Based on a material in the form of an oxide selected from at least one of the compounds comprising oxides, oxidized carbides or oxynitrides of Groups IIA, IIB, IVB, IIIA and IVA in the periodic table, such as oxides of Si, Sn Or otherwise based on a doped transparent metal oxide such as F: SnO ₂ . 31. The method of claim 29 or 30, wherein the inner complementary layer 2 and / or the outer complementary layer 4 are transparent at wavelengths in the visible light, in particular such as nitrides of Al, Ga or boron, A glass substrate (1) characterized in that it is based on material (s) in the form of nitride (s) based on at least one nitride of Group IIIA elements in the periodic table or else based on silicon nitride. 29. The material according to claim 28, wherein the inner complementary layer (2) and / or the outer complementary layer (4) are based on material (s) that are transparent at wavelengths in visible light and are in the form of carbon-like diamonds. Glass substrate (1). 30. The method of claim 29, wherein the inner complementary layer (2) and / or the outer complementary layer (4) is absorptive at wavelengths in visible light and differs from the composition of the reflective layer (3), W, Zr, Glass substrate (1) characterized in that it is based on a material consisting of nitrides of Hf, Nb or Ti, or carbon nitride, otherwise silicon (Si), which is preferably limited to 10 nm or less, in particular 1 to 8 nm. . 30. The method of claim 29 wherein the inner complementary layer 2 and / or the outer complementary layer 4 is based on progressively increasing SiO ₂ or SiO _x C _y in silicon or progressively at Al ₂ O ₃ increased SiO ₂ or SiO _x C of _y gradually increases in the thickness of the complementary layer (2) of the inner and / or TiO _2, based on Al ₂ O ₃ or SiO _x C _y or based on SiO ₂ or a SiO Glass substrate (1), characterized in that it has a chemical synthetic slope through the thickness of the outer complementary layer (4) based on Si gradually increasing at _x C _y or SiO ₂ . 35. The geometrical thickness of any one of claims 29 to 34, characterized in that the geometric thicknesses of the inner and outer complementary layers 2 and 4 are between 1 and 200 nm, in particular between 30 and 160 nm. Glass substrate (1). 36. The reflective layer (3) according to any one of claims 29 to 35, wherein the reflective layer (3) lies between the inner and outer complementary layers (2) and The properties and thickness of the reflective layer protect the properties of the reflective layer 3 during the high temperature deposition and after the deposition of the layer, if the glass substrate 1 is optionally subjected to post heat treatment in the form of annealing, bending or tempering, Glass substrate (1) characterized in that selected. 37. The glass substrate (1) according to any one of claims 29 to 36, characterized in that the reflective layer (3) has a density of at least 80% or more, in particular 90 to 95% of the theoretical density. 38. The glass substrate (1) according to any one of claims 29 to 37, wherein the reflective layer (3) has impurity levels of C, N and O of 3 at.% Or less, in particular 1 at.% Or less. One).