A heat treatable decorative glass substrate

Abstract

A heat treatable decorative glass substrate is disclosed comprising a stack of layers starting from the glass substrate: a lower dielectric layer, a substantially metallic silicon layer and an upper dielectric layer. The total thickness of all the layers in the stack of layers ranges between 75 nm and 230 nm in order to achieve the below combination of desired optical values and aesthetic external appearance: a desired transmission factor (TL) in visible radiation; external reflection (Rg) ranging between 10% and 40%; low internal reflection (Rc) of less than 25% or even less than 20%; and wide range of aesthetically pleasing external appearance.

Description

[0001] A HEAT TREATABLE DECORATIVE GLASS SUBSTRATE

[0002] Technical Field

[0003] The present invention, in general relates to a material comprising a transparent substrate, on the surface of which a stack of thin layers is deposited comprising a substantially metallic silicon layer. More specifically, the present invention relates to a heat treatable decorative glass article having aesthetically appealing external reflection colors and optimizable external reflection values as desired by customers.

[0004] Background

[0005] Decorative glazings known in the art and available in marketplaces generally comprise a thin layer or a stack of thin layers that act on incident radiation essentially by reflection. A strong reflection in the visible region of such a layer makes it possible to confer on the glazing, a mirror-like appearance, and a suitable color in reflection, when the glazing is seen from the outside of the building / cavity. Such glazings having aesthetically pleasing external appearances are used for creation of new architectural glasses for interior application. Another use of such glazing is to obtain savings in heating and cooling, using glazings that reflect heat rays.

[0006] Such glazings generally consist of sheets of glass coated with a metallic film of Cr, Al, Ni, Cu, Ag, Au, etc., or glass colored and coated with a metal oxide film (Fe, Co, Cr, Ni, Ti, Sn, etc.). To obtain a pleasant atmosphere inside the rooms, the transmission factor of visible radiation must be greater than 25%. To obtain a mirror like effect the reflection factor of visible radiation is brought to 40% or more. Among the glasses mentioned above, those which have a transmission of visible radiation greater than 25% and a satisfactory reflection power of heat radiation are glasses coated with an Au or Cu film. However, glazings with Au or Cu films are premium products that are quite expensive. Recent proposals of glass substrates comprising a silicon film on its surface present characteristics of having transmission factor of visible radiation greater than 25% and reflection of visible radiation greater than 40%. It would be useful to have a single glazing comprising silicon films with good power to reflect visible radiation on the glass side, obtaining a wide range of reflection values without increasing the coating side reflection and with appropriate visible transmission factor, all the above with aesthetically pleasing and varied external reflection color. Additionally advantageous would be to obtain all the above characteristics at an economical cost. Not many customers prefer the mirror-like effect on the coating side resulting from very high reflection of Si films as it predominantly shows one’s own reflection deterring from viewing the outside environment, particularly during nighttime.

[0007] Therefore, the present invention focuses on using a silicon film in a manner that the silicon film is sandwiched by dielectric layers to protect the film from alkali and other acid attacks and further focuses on lowering the reflection, particularly the internal reflection. Furthermore, the invention teaches to achieve different external reflection colors while maintain the internal reflection at values less than 25% and transmission factor in visible radiation ranging between 5% and 50%.

[0008] Prior art existing in said technical domain include a French application 2391173 owned by the assignee of the present invention that outlines a heat reflecting glass comprising a first silicon film provided on the surface of the glass substrate followed by a second film mainly consisting of metal oxide having excellent optical characteristics. This prior art desires to achieve the mirror effort and results in reflection values greater than 40%. US patent publication 20230202912 discloses a method of making a reflective coated glass having mirror-like appearances for concealing a video display when the display is not in use and permits a video image from the display to be bright and sharp when the display is in use and utilized in areas with high levels of natural light. The reflective glass comprises a first coating layer comprises elemental silicon and the second coating layer comprises silicon dioxide. US granted patent 11027526 owned by the assignee of the present invention is yet another prior art that aims at providing a glazing exhibiting a very high reflection in the visible region (380-780 nm), a suitable coloration in transmission, especially a bronze or golden coloration, with thermal, mechanical and chemical resistance in the application envisaged, especially in use as oven door. Here the glass article comprises the stack of layers having at least one layer of silicon nitride of formulation SiNx, in which x is less than 1.25. Light reflection in the visible region of the glass article, measured on the side where the stack or the layer is deposited, is greater than 20%.

[0009] It can be well understood from the above prior art references that silicon metallic layers when used as coating materials on glass substrate often result in increased reflection giving the mirror-like effect. With silicon being one the most cost effective materials, making a glazing article using merely a silicon layer for achieving all desired properties of the present invention lowers the operating cost significantly.

[0010] In particular, according to the present invention, the adjustment of the thicknesses of layers of silicon and sandwiching layers of dielectric materials offers the possibility to achieve different reflection colors with a range of low transmission to high transmission as desired by customers, while maintaining the internal reflection less than 25%.

[0011] It is thus a purpose of this disclosure to help achieve all the said characteristics, detail of which will become apparent to the skilled artisan once given the following disclosure.

[0012] Summary of the Disclosure

[0013] In one aspect of the present disclosure, a heat treatable decorative glass substrate is disclosed. Said heat treatable decorative glass substrate comprises a stack of layers starting from the glass substrate: a lower dielectric layer, a substantially metallic silicon layer and an upper dielectric layer. The lower and the upper dielectric layers are comprised of oxides or oxynitrides of Zn, Ti, Sn, Si, Al, Zr, Nb, Cr or nitrides of Si, Al. The stack of layers is characterized in that the total thickness of all the layers ranges between 75 nm and 230 nm to achieve a light reflection not greater than 25% when measured on the surface provided with the stack of layers and a light reflection ranging between 10% and 40% when measured on the surface not provided with the stack of layers.

[0014] Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

[0015] Brief Description of the Drawings

[0016] Embodiments are illustrated by way of example and are not limited to those shown in the accompanying figures.

[0017] FIG. 1 illustrates a stack of thin layers deposited on a transparent glass substrate, according to all embodiment of the present disclosure; and

[0018] FIG. 2 illustrates a stack of thin layers deposited on a transparent glass substrate, according to a specific embodiment of the present disclosure.

[0019] Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the invention.

[0020] Detailed Description

[0021] Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or similar parts. Embodiments disclosed herein are related to heat treatable glazings that find application mainly in retail or distribution market and desired for their low internal reflection values, variable external reflection values ranging between 10% and 40%, variable light transmission between 5% and 50% and advantageously for achieving all the above in a wide range of optical reflection colors as desired.

[0022] FIG. 1 illustrates a glass substrate 10 having a stack of thin layers 100 deposited on one of the surface of the glass substrate 10. The stack of layers 100 comprises two dielectric layers, lower dielectric layer 11 and an upper dielectric layer 13. Deposited between the lower dielectric layer 11 and the upper dielectric layer 13 is a substantially metallic silicon layer 12. The glass substrate 10 is particularly used in the field of glazing for building or motor vehicles. The term glazing is understood to mean, within the meaning of the present invention, any glass product composed of one or more glass substrates, in particular single glazings, double glazings, triple glazings, laminated glazings, and the like. The stack of thin layers 100 may further optionally comprise at least one protective layer 14 in contact with the dielectric layer 13.

[0023] Glazing having low transmission factor in visible radiation and high external reflection offer privacy features in the residential market. Inventors of the present invention have made use of an absorbing layer made of metallic silicon sandwiched between at least two dielectric coatings to achieve such a glazing. Adjusting the thicknesses of the metallic silicon and dielectric layers, offered a range of colored glazings whose transmission factor in visible radiation varied from low to high values. Additionally, the internal and external reflection factor in visible radiation of the glazing could also be modified without compromising the external aesthetic appearance of the glazings.

[0024] The inventors have worked with the coating 100 having the following stack of layers starting from the glass substrate: Dielectric layer [Ml] / Metallic Si layer [M2] / Dielectric layer [M3], In one embodiment of the present invention the coating 100 comprises of stack of layers starting from the glass substrate: Si3N4 / Metallic Si / Si3N4. The metallic silicon layer in the coating 100 controls the absorption in the visible radiation and allows to offer varying transmission levels to the glazings. In few embodiments of the present invention the coating 100 may comprise more than one dielectric layer Ml and more than one dielectric layer M3, in which case the coating 100 may comprise the stack of layers staring from the glass substrate: Dielectric layer 1 [Ml] / Dielectric layer 2 [Ml’] / Metallic Si layer [M2] / Dielectric layer 3 [M3] / Dielectric layer 4 [M3’].

[0025] In all embodiments of the present invention, the dielectric layer Ml (referred to as 11 in Fig. 1) and dielectric layer M2 (referred to as 13 in Fig. 1) are made of one or more oxide layers made of Zn, Ti, Sn, Si, Al, Zr, Nb, Cr or one or more nitride layers made of Si, Al or one or more oxynitride layers made of Zn, Ti, Sn, Si, Al, Zr, Nb, Cr. According to multiple embodiments of the present invention the dielectric layers 11, 13 can be made of the same or different layer materials. Nonetheless, the coating 100 in all embodiments of the present invention comprises no layer(s) based on silver.

[0026] According to additional optional embodiments of the present invention, the dielectric layer Ml (referred to as 11 in Fig. 1) and dielectric layer M2 (referred to as 13 in Fig. 1) may further comprise Al, Zr, Ti, Hf and / or B as dopants. Preferably the dopant material present in dielectric layers 11, 13 is Al. According to preferred embodiments of the present invention, the dielectric layers 11, 13 are made of silicon nitride which can be optionally doped with Al.

[0027] The total thickness of the dielectric layer(s) 11 directly deposited on one of the surfaces of the glass substrate 10 does not exceed 70 nm. Preferably, the total thickness of the dielectric layer(s) 11 ranges between 20 nm and 70 nm. More preferably, the total thickness of the dielectric layer(s) 11 ranges between 30 nm and 65 nm. The total thickness of the dielectric layer(s) 13 directly deposited on the metallic silicon layer 12 ranges between 25 nm and 100 nm. Preferably, the total thickness of the dielectric layer(s) 13 ranges between 30 nm and 80 nm. More preferably, the total thickness of the dielectric layer(s) 13 ranges between 40 nm and 70 nm.

[0028] The metallic silicon layer 12 of the coating 100 in a few embodiments of the present invention is a substantially metallic layer wherein the layer 12 may comprise nitrogen or oxygen as a result of deposition process or as a result of the heat treatment. In these embodiments, the silicon layer may include trace contaminants of, for example, carbon. As used herein, the phrase “trace amount” is an amount of a constituent of a coating layer that is not always quantitatively determinable because of its minuteness. However, it is preferred that the silicon layer is essentially free of contaminants such as carbon.

[0029] During the deposition process it could be likely that that the atmosphere at which the metallic silicon layer is deposition on the glass substrate may comprise nitrogen or oxygen in trace quantities. Likewise, during the heating process of the glass substrate there is a good probability of migration of elemental nitrogen or oxygen from the adjoining layers of dielectric material into the metallic silicon layer. Owing to one or both of the above said reasons, the metallic silicon layer 12 may comprise nitrogen, however in all embodiments of the present invention such nitrogen present in the metallic silicon layer 12 does not exceed 22 mol%. Likewise, when the metallic silicon layer 12 comprises oxygen and nitrogen, the mol% of oxygen and nitrogen put together does not exceed 22 mol%.

[0030] In all embodiments the thickness of the substantially metallic silicon layer 12 does not exceed 80 nm. Preferably, the thickness of the substantially metallic silicon layer 12 ranges between 10 nm and 70 nm. More preferably, the thickness of the substantially metallic silicon layer 12 ranges between 15 nm and 60 nm.

[0031] According to a few optional embodiments, the coating 100 further comprises a protective layer 14 which when is the outermost layer of the coating 100. The protective layer 14 when present is made of titanium oxide or zirconium oxide or titanium zirconium oxide. The thickness of the protective layer 14 when present ranges between 1 nm and 5 nm.

[0032] As illustrated in Fig. 2, according to a specific embodiment the coating 100 comprises the sequence of the following layers, starting from the surface of the glass substrate: a lower dielectric layer made of silicon nitride having a physical thickness ranging between 5 nm and 70 nm; a metallic silicon layer having a physical thickness ranging between 5 nm and 70 nm; an upper dielectric layer made of silicon nitride having a physical thickness ranging between 40 nm and 100 nm; and a protective layer made of titanium oxide having a physical thickness ranging between 1 nm and 5 nm.

[0033] For the glazing of the present invention to have the following desirable characteristics: a desired transmission factor (TL) in visible radiation; external reflection (Rg) ranging between 10% and 40%; and low internal reflection (Rc) of less than 25% or even less than 20%, the inventors of the present invention have determined that the total thickness of all the layers in the coating 100 should range between 75 nm and 230 nm. Preferably, the total thickness of all the layers in the coating 100 ranges between 100 nm and 200 nm. More preferably, the total thickness of all the layers in the coating 100 should range between 110 nm and 190 nm.

[0034] The light reflection in the visible region of the glass article, on the stack side (Rc), is less than 25%, preferably less than 20%, more preferably less than 15% or even less than 10%.

[0035] The coating 100 is deposited over the glass substrate 10. Preferably the coating 100 is formed directly on the surface of the glass substrate 10. When the coating 100 is formed directly on the glass substrate 10, there are no intervening coatings between the coating 100 and the glass substrate 10. A surface of the glass substrate 10 opposite to the surface deposited with the coating 100 may be uncoated.

[0036] In an embodiment, the coating 100 is pyrolytic. As used herein, the term “pyrolytic” may refer to a coating or a layer thereof that is chemically bonded to a glass substrate. Preferably, the coating 100 is formed physical vapor deposition (PVD) processes. In certain embodiments, each PVD process is a dynamic deposition process. Thus, in these embodiments, the glass substrate 10 is moving at the time of forming the coating 100 thereon or thereover.

[0037] The transparent substrates according to the present invention are preferably made of an inorganic rigid material, such as glass, or an organic material based on polymers (or made of polymer). The substrate is preferably a sheet of glass or of glass-ceramic. The substrate is preferably transparent, colorless (it is then a clear or extra-clear glass) or colored, for example colored blue, grey, green or bronze. The glass substrate may be of a conventional glass composition known in the art. In certain embodiments, the composition of the glass substrate 10 is selected to allow the coated glass article according to the present invention to exhibit certain properties. In this embodiment, the substrate 12 may be a float glass ribbon. The glass is preferably of soda-lime-silica type, but it may also be made of glass of borosilicate or alumino-borosilicate type. The substrate advantageously has at least one dimension greater than or equal to 1 m, or even 2 m and even 3 m. The thickness of the substrate generally varies between 0.5 mm and 19 mm, preferably between 0.7 and 9 mm, in particular between 2 and 12 mm, or even between 4 and 10 mm. The substrate may be flat or curved, or even flexible.

[0038] The coated glass article prepared according to the present invention can be mounted or employed according to any known form, for example in a single glazing, in a multiple glazing, for example double glazing, or else in a laminated glazing. The term laminated glazing is conventionally understood to mean a glazing comprising at least two glass substrates united by a plastic sheet, for example of the PVB or PU type.

[0039] According to a first example, when the stack is deposited on a single glazing which could be an element of an oven door or a building glazing, this can advantageously be positioned on face 1 of the glazing, that is to say on the face of the glazing directed toward the inside of the cavity of the oven or inside of a room of the building.

[0040] According to another example, when the stack is deposited on a constituent double glazing of an oven door or a building glazing, this can advantageously be positioned on face 2 or 3 of the glazing, preferably on face 2 of the glazing, the faces of the glazing being numbered from the inside (the cavity) of the oven or building toward the outside of said oven or building. In such a configuration, the stack is thus positioned between the two glass substrates of the double glazing and is thus protected.

[0041] The glass substrate can be used directly without additional treatment or alternatively can be used after having been subjected to a heat treatment which can be a tempering, a bending or a bending / tempering or annealing or strengthening, without loss of its optical properties described herein. Such a tempering step consists, for example, of a heat treatment for 5 to 10 minutes at a temperature of between 600 and 750° C.

[0042] A glazing according to the invention also makes it possible to reflect a substantial portion of the light radiation passing through it, the wavelength of which is between approximately 380 and 780 nm. In addition, the glass products according to the invention are resistant to moisture, to scratching and to acid attacks. In particular, the glazings according to the invention exhibit an improved longevity, in the sense that their initial properties, in particular their variation in color and their optical properties, vary only very slightly under the chemical attacks to which they are subjected during their planned use.

[0043] They can thus advantageously be used as single glazing (just one glass substrate).

[0044] A process for the manufacture of a glass article according to the invention comprises, for example, the following stages: manufacture of a glass substrate, deposition, on the glass substrate, of a stack of layers by a vacuum cathode sputtering technique, preferably a magnetron-assisted one, including a layer of metallic silicon sandwiched by dielectric layers according to the invention, said layer being obtained by sputtering of a target comprising or essentially composed of silicon in an atmosphere comprising nitrogen and an ideal gas.

[0045] Examples

[0046] Example 1

[0047] The examples which follow are given purely by way of illustration and do not limit, under any of the aspects described, the scope of the present invention. For purposes of comparison, all the stacks of the examples which follow are synthesized on the same Planiclear® glass substrate. All the layers of the stacks were deposited according to the well-known conventional techniques of vacuum depositions by magnetron sputtering. The transparency or absorption characteristics of the glass substrate may vary between embodiments of the coated glass article. Also, the color of the glass substrate can vary between embodiments.

[0048] Table 1 lists the materials and thicknesses in nanometers for each layer or coating that forms the stacks as a function of their position with respect to the substrate bearing the stack (final line at the bottom of the table). The “Ref.” numbers correspond to the references from FIG. 1. The comparative samples are construed for comparison. Table 1 : Stack of thin layers (Inventive Samples)

[0049] Table 2: Stack of thin layers (Comparative Samples) Solar Control and Optical Properties

[0050] Table 3 lists the main optical characteristics measured when the glazings are part of a monolithic glazing of 6 mm glass. For these monolithic glazings:

[0051] TL indicates: the light transmission in the visible region in %, measured according to the illuminant D65 Obs 2; a*T and b*T indicate the a* and b* colors in transmission in the L*a*b* system measured according to the illuminant D65 Obs 2 and measured perpendicularly to the glazing;

[0052] RG indicates: the light reflection in the visible region in %, measured according to the illuminant D65 Obs 2 on the glass side of the glazing; a*RG and b*RG indicate the a* and b* colors in reflection in the L*a*b* system measured according to the illuminant D65 Obs 2 on the glass side of the glazing and thus measured at 8 deg from the glazing normal incidence;

[0053] RC indicates: the light reflection in the visible region in %, measured according to 5 the illuminant D65 Obs 2 on the coating side of the glazing; a*RC and b*RC indicate the a* and b* colors in reflection in the L*a*b* system measured according to the illuminant D65 Obs 2 on the coating side of the glazing and thus measured at 8 deg from the glazing normal incidence.

[0054] 10 Table 3: Optical & Solar Control Properties [Inventive Examples]

[0055] Table 4: Optical & Solar Control Properties [Comparative Examples]

[0056] It can be well understood from Table 2 that comparative samples are not prepared according to the teachings of the present invention. Samples A of the comparative example has an upper dielectric layer 13 much thicker than taught in the present invention. Sample B has a lower dielectric layer 11 much thicker than taught in the present invention. Samples C & D of the comparative example has a total thickness of layers above 230 nm, higher than that taught in the present invention. Additionally, sample D has a metallic silicon layer whose thickness is also much higher than the desired thickness taught in the present invention. Sample E of the comparative example has a total thickness of layers much less than the desired thickness range i.e., less than 75 nm and further has an upper dielectric layer less than 25 nm. As a result, the optical values of such comparative samples can be seen to have high internal reflection above 25%. Additionally sample D can be seen to have a very low transmission value and sample E can be seen to have a higher external reflection >40%.

[0057] As for the inventive examples, it can be seen that all the layers of the stack of thin layers are deposited according to the teachings of the present invention and such coatings result in glazings having the combination of all the desired aesthetic and optical properties. Samples 1 - 13 demonstrate how glazing having a low to high transmission factor in visible radiation can be achieved using the coating of the present invention. Advantageously, such glazings having variable light transmission factors, all have less internal reflection value of <25% as is desired by the customers. This gives the customers flexibility and choice to vary the visible transmission levels while maintaining a less internal reflection thereby promising optical comfort for individuals seated inside the building. Additionally, external reflection of none of these samples are greater than 40% thereby avoiding the mirror-like appearance which is not desired by the customers. Furthermore, sample 1 - 13 can be seen to be to achieve varied external reflection colors to suit the many choices of the customers, including a lime green or a chartreuse green achieved by sample 10. The inventive samples and comparative samples were heat treated (tempered) at 630°C for upto 12 minutes. The results demonstrate that the optical properties of samples do not influence the tempering shift in the sample and the results are similar.

[0058] Industrial Applicability

[0059] The coated glass article, in one embodiment is utilized as a portion of a display assembly. Additionally, the embodiments of the coated glass article may be utilized in, for example, a glazing and / or have architectural, electronic, residential, commercial, photovoltaic, automotive, and aerospace applications.

[0060] According to few other embodiments, the glass article is used as (conventional or microwave) oven door or else as article for protection of an oven. The article can also be used for other household electrical applications, as gas cooker cover, wine cellar door, refrigerator door, frying pan protection, and the like.

[0061] The glass article can also be used as building glazing or else as motor vehicle glazing.

[0062] The tempered glazing can also be used in building wall cladding panel of curtain walling for interior applications. Further can also be used as a side window, rear window or sunroof for an automobile or other vehicle.

[0063] Note that not all of the activities described above in the general description or the examples are required, that a portion of a specific activity may not be required, and that one or more further activities may be performed in addition to those described. Still further, the order in which activities are listed is not necessarily the order in which they are performed.

[0064] Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any feature(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature of any or all the claims. The specification and illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The specification and illustrations are not intended to serve as an exhaustive and comprehensive description of all of the elements and features of apparatus and systems that use the structures or methods described herein. Certain features, that are for clarity, described herein in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in a sub combination. Further, reference to values stated in ranges includes each and every value within that range. Many other embodiments may be apparent to skilled artisans only after reading this specification. Other embodiments may be used and derived from the disclosure, such that a structural substitution, logical substitution, or another change may be made without departing from the scope of the disclosure. Accordingly, the disclosure is to be regarded as illustrative rather than restrictive.

[0065] The description in combination with the figures is provided to assist in understanding the teachings disclosed herein, is provided to assist in describing the teachings, and should not be interpreted as a limitation on the scope or applicability of the teachings. However, other teachings can certainly be used in this application.

[0066] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive-or and not to an exclusive-or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present). Also, the use of "a" or "an" is employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural, or vice versa, unless it is clear that it is meant otherwise. For example, when a single item is described herein, more than one item may be used in place of a single item. Similarly, where more than one item is described herein, a single item may be substituted for that more than one item.

[0067] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The materials, methods, and examples are illustrative only and not intended to be limiting. To the extent that certain details regarding specific materials and processing acts are not described, such details may include conventional approaches, which may be found in reference books and other sources within the manufacturing arts.

[0068] While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.

[0069] List of Elements

[0070] TITLE: A HEAT TREATABLE DECORATIVE GLASS SUBSTRATE

[0071] 10 Glass Substrate

[0072] 11 First Dielectric Layer Ml

[0073] 12 Metallic Layer

[0074] 13 Second Dielectric Layer M2

[0075] 14 Protective Layer

Claims

We claim,1) A heat treatable decorative glass substrate comprising a stack of layers starting from the glass substrate: a lower dielectric layer comprised of oxides or oxynitrides of Zn, Ti, Sn, Si, Al, Zr, Nb, Cr or nitrides of Si, Al; a substantially metallic silicon layer; and an upper dielectric layer comprised of oxides or oxynitrides of Zn, Ti, Sn, Si, Al, Zr, Nb, Cr or nitrides of Si, Al, characterized in that the total thickness of all the layers ranges between 75 nm and 230 nm.2) The heat treatable decorative glass substrate as claimed in claim 1, wherein the substantially metallic silicon layer comprises less than 22 mol% of Nitrogen.3) The heat treatable decorative glass substrate as claimed in claim 1, wherein the substantially metallic silicon layer may comprise oxygen.4) The heat treatable decorative glass substrate as claimed in claim 1, wherein the substantially metallic silicon layer may comprise less than 22 mol% of oxygen and nitrogen in total.5) The heat treatable decorative glass substrate as claimed in claim 1, wherein the lower and upper dielectric layers can be made of same or different material.6) The heat treatable decorative glass substrate as claimed in claim 1, wherein the lower and upper dielectric layers may further comprise Al, Zr, Ti, Hf and / or B as dopants.7) The heat treatable decorative glass substrate as claimed in claim 1, wherein the lower dielectric layer has a total thickness not exceeding 70 nm.8) The heat treatable decorative glass substrate as claimed in claim 1, wherein the upper dielectric layer has a total thickness ranging between 25 nm and 100 nm.9) The heat treatable decorative glass substrate as claimed in claim 1, wherein the substantially metallic silicon layer has a thickness not exceeding 80 nm.10) The heat treatable decorative glass substrate as claimed in claim 1, wherein the stack of layers further comprises a protective layer made of titanium oxide or zirconium oxide or titanium zirconium oxide.11) The heat treatable decorative glass substrate as claimed in claim 1, wherein the stack of layers does not comprise any layers based on silver.12) The heat treatable decorative glass substrate as claimed in claim 1, is subjected to heat treatments including tempering, bending and heat strengthening.13) The heat treatable decorative glass substrate as claimed in claim 12, wherein heat treatments involve temperatures ranging between 300 °C and 800 °C.14) The heat treatable decorative glass substrate as claimed in claim 1 has a light reflection not greater than 25% when measured on the surface provided with the stack of layers and a light reflection ranging between 10% and 40% when measured on the surface not provided with the stack of layers.

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