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Low-Emissivity Coating for a Glass Substrate

20190330101 · 2019-10-31

    Inventors

    Cpc classification

    International classification

    Abstract

    The present invention relates to a glass substrate provided with a stack of thin coating layers formed by a first layer of anti-reflective dielectric material, with a refractive index of 1.65 to 2.65, located above the glass substrate. At least one structure of two layers formed by a first layer of an anti-reflective transparent dielectric material with a refractive index of 1.32 to 1.55, located in the bottom position, and a second layer of a metal functional layer with reflective properties in the infrared range, located in the top position, said structure being located above the first layer of anti-reflective dielectric material. A second layer of absorbent material forming an anti-corrosion barrier for protecting the metal functional layer against oxidation and corrosion. A third layer of an anti-reflective material, said layer being selected from a metal oxide with a refractive index of 1.32 to 1.55, a metal oxide with a refractive index of 1.65 to 1.95 or an aluminum-doped zinc oxide (AZO); and a fourth protective layer made of an anti-reflective material, for increasing the transmission of visible light and the scratch resistance of the substrate, having high transmission of visible light (60%), a solar transmission of less than 60%, a resistance of less than 10 per square and an emissivity of less than 0.10.

    Claims

    1. A glass substrate provided with a stack of thin coating layers which comprises: a first layer of an anti-reflective dielectric material, with a refractive index between 1.65 and 2.65, located above the glass substrate; at least a two-layer structure including: a first layer of an anti-reflective transparent dielectric material with a refractive index between 1.32 and 1.55, located in the lower position, and a second layer of a metal functional layer with reflection properties in the infrared range for the upper position, this structure being located above the first layer of anti-reflective dielectric material; a second layer of an absorbent anti-corrosion barrier material, to protect the metal functional layer from oxidation and corrosion, this layer of absorbent material is placed over the metal functional layer of the two-layer structure during the deposition of the top layers and/or the glass tempering process; a third layer of an anti-reflective material, this layer being selected from a metal oxide with a refractive index between 1.32 and 1.55, a metal oxide with a refractive index between 1.65 and 1.95 or an aluminum-doped zinc oxide (AZO); and, a fourth layer of anti-reflective material protection to increase visible light transmission and scratch resistance of the substrate, showing a high visible light transmission (>60%), less than 60% solar transmission, less than 10 per square and less than 0.10 emissivity.

    2. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the first layer of anti-reflective dielectric material being selected from the group of nitrites, metal oxides of the TiO.sub.2 group or a combination of both.

    3. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the first layer of dielectric anti-reflective material comprises: at least one selected metal oxide layer with a refractive index between 1.65 and 1.95 and a thickness between 10 and 40 nm thick, which is superimposed on the glass substrate.

    4. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the first layer of dielectric anti-reflective material comprises: at least one selected metal oxide layer with a refractive index between 1.65 and 1.95 and a thickness between 10 to 40 nm, which is superimposed on the glass substrate.

    5. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the first layer of the anti-reflective dielectric material is silicon nitride (Si.sub.3N.sub.4).

    6. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the first layer of dielectric anti-reflective material comprises: a first pre-layer with a refractive index between 1.65 and 1.95 and a thickness between 10 and 40 nm, located above the glass substrate; and a second pre-layer, above the first pre-layer with a refractive index greater than 2 and a thickness between 1 and 10 nm.

    7. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the first layer of dielectric anti-reflective material comprises: a first pre-layer with a refractive index between 1.65 and 1.95 and a thickness between 10 and 40 nm, located above the glass substrate; and a second pre-layer above the first pre-layer with a refractive index between 2.1 and 2.5 and a thickness between 1 and 10 nm.

    8. The glass substrate provided with a stack of thin coating layers as claimed in claim 7, wherein the first pre-layer of the first dielectric anti-reflective layer is selected from silicon nitride (Si.sub.3N.sub.4).

    9. The glass substrate provided with a stack of thin coating layers as claimed in claim 7, wherein the second pre-layer of the first layer of the anti-reflective dielectric material is selected from titanium, zirconium, zinc, tin and niobium oxides, silicon nitrides, chromium, zirconium or titanium.

    10. The glass substrate provided with a stack of thin coating layers as claimed in claim 7, wherein the anti-reflective transparent dielectric material of the two-layer structure is a transparent metallic oxide or a conductive transparent oxide with a thickness between 8 and 20 nm.

    11. The glass substrate provided with a stack of thin coating layers as claimed in claim 10, wherein the transparent metal oxide is zinc oxide (ZnO).

    12. The glass substrate provided with a stack of thin coating layers as claimed in claim 10, wherein the conductive transparent oxide is aluminum-doped zinc oxide (AZO).

    13. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the first layer of the anti-reflective transparent dielectric material of two-layer structure is a transparent metal oxide or conductive transparent oxide with a thickness between 8 and 20 nm.

    14. The glass substrate provided with a stack of thin coating layers as claimed in claim 13, wherein the transparent metal oxide is zinc oxide (ZnO).

    15. The glass substrate provided with a stack of thin coating layers as claimed in claim 10, wherein the conductive transparent oxide is aluminum-doped zinc oxide (AZO).

    16. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the first layer of anti-reflective transparent dielectric material of two-layer structure is a transparent metal oxide or conductive transparent oxide with a thickness between 50 and 90 nm.

    17. The glass substrate provided with a stack of thin coating layers as claimed in claim 16, wherein the transparent metal oxide is zinc oxide (ZnO).

    18. The glass substrate provided with a stack of thin coating layers as claimed in claim 16, wherein the conductive transparent oxide is aluminum-doped zinc oxide (AZO).

    19. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the first layer of anti-reflective transparent dielectric material of two-layer structure is a transparent metal oxide or conductive transparent oxide with a thickness between 50 and 90 nm.

    20. The glass substrate provided with a stack of thin coating layers as claimed in claim 19, wherein the transparent metal oxide is zinc oxide (ZnO).

    21. The glass substrate provided with a stack of thin coating layers as claimed in claim 19, wherein the conductive transparent oxide is aluminum-doped zinc oxide (AZO).

    22. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein functional metal layer in the structure is a noble metal selected from Al, Ag, Au, Cu or Pt with a thickness between 5 and 15 nm.

    23. (canceled)

    24. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the second layer of an absorbent material is a NiCr alloy (80:20% p/p) or a nickel-chrome alloy oxide (NiCrOx), the second layer having a thickness between 0.5 and 5 nm.

    25. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the third layer of the anti-reflective material is ZnO, SnO.sub.2 or a transparent semiconductor oxide, the third layer having a thickness between 8 and 15 nm.

    26. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the third layer of anti-reflective material is ZnO, SnO.sub.2 or a transparent semiconductor oxide, the third layer having a thickness between 8 and 20 nm.

    27. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the third layer of the anti-reflective material is ZnO, SnO.sub.2 or a transparent semiconductor oxide, the third layer having a thickness between 8 and 30 nm.

    28. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the third layer of the anti-reflective material is ZnO, SnO.sub.2 or a transparent semiconductor oxide, the third layer having a thickness between 20 and 40 nm.

    29. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the fourth layer of protection is an anti-reflective material of the group of nitrides, oxides or silicates of zirconium or silicon, the anti-reflective material having a thickness between 10 and 50 nm.

    30. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the fourth layer of protection is an anti-reflective material of the nitrides, oxides or silicates of zirconium or silicon group, the fourth layer having a thickness between 8 and 20 nm.

    31. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the fourth layer of protection is an anti-reflective material of the nitrides, oxides or silicates of zirconium or silicon group, the fourth layer having a thickness between 10 and 40 nm.

    32. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, which comprises the following structure: glass substrate/Si.sub.3N.sub.4/ZnO/Ag/NiCr/ZnO/Si.sub.3N.sub.4 o ZrO.sub.2 o ZrSiO.sub.2.

    33. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, which comprises the following structure: glass substrate/Si.sub.3N.sub.4/TiO.sub.2/ZnO/Ag/NiCr o NiCrOx/AZO/Si.sub.3N.sub.4.

    34. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, which comprises the following structure: glass substrate/Si.sub.3N.sub.4/TiO.sub.2/AZO/Ag/NiCr o NiCrOx/AZO/Si.sub.3N.sub.4.

    35. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, which comprises the following structure: glass substrate/Si.sub.3N.sub.4/ZnO/Ag/AZO/Ag/NiCr o NiCrOx/AZO/Si.sub.3N.sub.4.

    36. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, which comprises the following structure: glass substrate/Si.sub.3N.sub.4/AZO/Ag/AZO/Ag/NiCr o NiCrOx/AZO/Si.sub.3N.sub.4.

    37. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, which comprises the following structure: glass substrate/Si.sub.3N.sub.4/TiO.sub.2/AZO/Ag/AZO/Ag/NiCr o NiCrOx/AZO/Si.sub.3N.sub.4.

    38. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, which comprises the following structure: glass substrate/Si.sub.3N.sub.4/ZnO/Ag/AZO/Ag/AZO/Ag/NiCrOx/AZO/Si.sub.3N.sub.4.

    39. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, which comprises the following structure: glass substrate/Si.sub.3N.sub.4/AZO/Ag/AZO/Ag/AZO/Ag/NiCrOx/AZO/Si.sub.3N.sub.4.

    40. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, which comprises the following structure: glass substrate/Si.sub.3N.sub.4/TiO.sub.2/ZnO/Ag/AZO/Ag/AZO/Ag/NiCrOx/AZO/Si.sub.3N.sub.4.

    41. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the thicknesses of the two-layer structure with the following sequence: ZnO or AZO/Ag are 8 to 15 nm/5 to 15 nm.

    42. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the thicknesses of two two-layer structures with the following sequence: ZnO or AZO/Ag/AZO are 8 to 15 nm/5 to 15 nm/50 to 90 nm/5 to 15 nm.

    43. The glass substrate provided with a stack of thin coating layers as claimed in claim 1, wherein the thicknesses of three two-layer structures with the following sequence: ZnO or AZO/Ag/AZO/Ag/AZO/Ag/Ag/AZO are 8 to 20 nm/5 to 15 nm/50 to 90 nm/5 to 15 nm/50 to 90 nm/5 to 15 nm.

    Description

    BRIEF DESCRIPTION OF THE FIGURES

    [0029] FIG. 1 shows the schematic diagram of a coating that includes a structure formed by a first layer of an anti-reflective transparent dielectric material and a second layer of a functional metallic film with reflection properties in the infrared range, according to an embodiment of the present invention;

    [0030] FIG. 2 shows the schematic diagram of a coating that includes a structure formed by a first layer of an anti-reflective transparent dielectric material and a second layer of a functional metallic film with reflection properties in the infrared range, according to a second embodiment of the present invention;

    [0031] FIG. 3 shows the schematic diagram of a coating that includes a structure formed by a first layer of an anti-reflective transparent dielectric material and a second layer of a functional metallic film with reflection properties in the infrared range, according to a third embodiment of the present invention;

    [0032] FIG. 4 shows the schematic diagram of a coating with two overlapping structures formed by a first layer of an anti-reflective transparent dielectric material and a second layer of a functional metallic film with reflection properties in the infrared range, according to a fourth embodiment of the present invention;

    [0033] FIG. 5 shows the schematic diagram of a coating with two overlapping structures formed by a first layer of an anti-reflective transparent dielectric material and a second layer of a functional metallic film with reflection properties in the infrared range, according to a fifth embodiment of the present invention;

    [0034] FIG. 6 shows the schematic diagram of a coating with two overlapping structures formed by a first layer of an anti-reflective transparent dielectric material and a second layer of a functional metallic film with reflection properties in the infrared range, according to a sixth embodiment of the present invention;

    [0035] FIG. 7 shows the schematic diagram of a coating with three overlapping structures formed by a first layer of an anti-reflective transparent dielectric material and a second layer of a functional metallic film with reflection properties in the infrared range, according to a seventh embodiment of the present invention;

    [0036] FIG. 8 shows the schematic diagram of a coating with three overlapping structures formed by a first layer of an anti-reflective transparent dielectric material and a second layer of a functional metallic film with reflection properties in the infrared range, according to an eighth embodiment of the present invention;

    [0037] FIG. 9 shows the schematic diagram of a coating with three overlapping structures formed by a first layer of an anti-reflective transparent dielectric material and a second layer of a functional metallic film with reflection properties in the infrared range, according to a ninth embodiment of the present invention;

    [0038] FIG. 10 shows the light transmission values according to different examples of the present invention; and,

    [0039] FIG. 11 shows the Resistivity values according to different examples of the present invention.

    DETAILED DESCRIPTION OF THE INVENTION

    First Embodiment (Example 1)

    [0040] In a first embodiment of the invention, a low emissivity coating deposited on a glass sheet is comprised in the following layer structure and is illustrated in FIG. 1.

    [0041] A first layer of anti-reflective dielectric material (12) with a refractive index between 1.65 and 1.95 is applied to a glass substrate (10). Layer one can be silicon nitride (Si.sub.3N.sub.4) between 10 and 40 nm thick, but preferably from 10 to 25 nm. This compound promotes the adherence of the coating to the substrate and blocks the migration of sodium from the glass.

    [0042] A second coating layer (18) consists of an anti-reflective dielectric material with a refractive index between 1.32 and 1.55. Transparent dielectric materials can be used that include metallic oxides with refractive index >2.0, however, in the present invention zinc oxide (ZnO) is used, which is deposited on Si.sub.3N.sub.4 between 8 and 15 nm thick, and preferably between 8 and 10 nm. This layer acts as a template for the proper growth of a high reflectivity infrared (IR) energy material, as well as acting as an anti-reflective layer.

    [0043] A third layer (20) corresponds to a material that provides high reflectivity in the infrared region and low absorption in the visible range. This layer is applied over the anti-reflective dielectric coating (18), between 5 and 15 nm thick, preferably from 8 to 12 nm. Noble metals such as: Al, Ag, Au, Cu and Pt are commonly used, however silver is preferred because it gives a neutral aesthetic appearance to coating.

    [0044] A fourth layer consists of an absorbent material which also acts as an anti-corrosion barrier (22). In the present invention a NiCr alloy is used (80:20% p/p), because it is able to capture water vapor, oxygen, nitrogen or other compounds capable of reacting and degrading the metallic silver layer. Its primary function is to protect silver from oxidation and corrosion during upper layer deposition and/or glass tempering process. Some embodiments of the present invention prefer the barrier layer to be partially oxidized (NiCrOx) to increase the visible transmission in the coating. The barrier layer (22) ranges between 0.5 and 5 nm thick, preferably between 0.5 and 2 nm.

    [0045] A fifth layer of an anti-reflective dielectric material (24) with a refractive index between 1.32 and 1.55, such as ZnO. The thickness of this anti-reflective layer (24) is between 8 and 15 nm, preferably between 10 and 12 nm. Some examples of this invention show that zinc oxide has a double function in the coating. If applied before the silver layer, ZnO acts as a nucleating agent to achieve the proper growth of the layer, provided that wurtzite type ZnO films with a texture oriented towards c-axis, are obtained. On the other hand, if placed after the reflective layer, the ZnO acts as a blocking and non-absorbent layer, which also helps maintaining the electrical conductivity of Ag, due to its electronic nature.

    [0046] Finally, in this embodiment, a dielectric material is placed as a protective layer (26). This layer provides mechanical stability, thermal stability, chemical durability and scratch resistance to the entire coating. Materials such as: Si.sub.3N.sub.4, ZrO.sub.2, ZrSiO.sub.2, etc. can be used. This invention uses Si.sub.3N.sub.4 as a protection layer (26), a thickness between 10 and 50 nm, preferably between 20 and 45 nm.

    Second Embodiment (Example 2)

    [0047] In a second embodiment of this invention, a low emissivity coating composed of an arrangement of layers is proposed as shown in FIG. 2.

    [0048] On a glass substrate (10) a first dielectric layer (12) composed of a first pre-layer (14) with a refractive index between 1.65 and 1.95 is deposited, on which a second sub-layer (16) of a refractive index between 2.1 and 2.5 is deposited. In this embodiment, the first pre-layer (14) is formed by silicon nitride (Si.sub.3N.sub.4), between 10 and 40 nm thick, preferably between 10 and 25 nm, while the additional second sub-layer (16) is 1 to 10 nm thick and corresponds to an anti-reflective compound with a refractive index higher than 2, e.g. titanium dioxide (TiO.sub.2).

    [0049] A second layer consists of an anti-reflective dielectric material (18) with a refractive index between 1.32 and 1.55. Transparent dielectric materials can be used that include metallic oxides with refractive index >2.0, however, in the present invention zinc oxide (ZnO) is used, which is deposited on Si.sub.3N.sub.4 between 8 and 15 nm thick, preferably from 8 to 10 nm. In addition to increasing the anti-reflective characteristics of the coating, it acts as a template for the proper growth of a high reflectivity (IR) infrared energy material.

    [0050] A third layer corresponds to a material that provides high reflectivity in the infrared region and low absorption in the visible range (20). This layer is applied over the anti-reflective dielectric coating (18), between 5 and 15 nm thick, preferably from 8 to 10 nm. Noble metals such as: Al, Ag, Au, Cu and Pt are commonly used, however silver is preferred because it gives a neutral aesthetic appearance to coating.

    [0051] A fourth layer consists of an absorbent material which also acts as an anti-corrosion barrier (22). In the present invention a NiCr alloy is used (80:20% p/p), because it is able to capture water vapor, oxygen, nitrogen or other compounds capable of reacting and degrading the metallic silver layer. Its primary function is to protect silver from oxidation and corrosion during upper layer deposition and/or glass tempering process. Some embodiments of the present invention prefer the barrier layer to be partially oxidized (NiCrOx) to increase the visible transmission in the coating. The barrier layer thickness (22) ranges is between 0.5 and 5 nm, preferably between 0.5 and 2 nm.

    [0052] A fifth layer of the coating consists of an anti-reflective dielectric material (24) with a refractive index between 1.32 and 1.55, such as ZnO. However, some examples of this invention, SnO.sub.2 (refractive index 2.0) can be used instead of ZnO. The thickness of this anti-reflective dielectric layer (24) is between 8 and 15 nm, preferably between 10 and 12 nm.

    [0053] Finally, in this embodiment, a dielectric material is placed as a protective layer (26). This layer provides mechanical stability, thermal stability, chemical durability and scratch resistance to the entire coating. Materials such as: Si.sub.3N.sub.4, ZrO.sub.2, ZrSiO.sub.2, etc. can be used. This invention uses Si.sub.3N.sub.4 as a protection layer (26), between 10 and 50 nm thick, preferably between 20 and 45 nm.

    Third Embodiment (Example 3)

    [0054] In a third embodiment of this invention, a low emissivity coating is proposed consisting of a layer arrangement as shown in FIG. 3.

    [0055] On a glass substrate (10) a first dielectric layer (12) composed of a first pre-layer (14) with a refractive index between 1.65 and 1.95 is deposited, on which a second sub-layer (16) of a refractive index between 2.1 and 2.5 is deposited. In this embodiment, the first pre-layer (14) is formed by silicon nitride (Si.sub.3N.sub.4), between 10 and 40 nm thick, preferably between 10 and 25 nm, while the second sub-layer (16) is 1 to 10 nm thick and corresponds to an anti-reflective compound with a refractive index higher than 2, e.g. titanium dioxide (TiO.sub.2).

    [0056] A second layer of the coating (28) consists of a conductive transparent oxide such as aluminum-doped Zinc Oxide (AZO), between 8 and 20 nm thick, preferably between 8 and 10 nm. Inclusion of this layer in the multilayer heterostructure increases transmission (T.sub.luz) and reduces light reflection (R.sub.luz), improves chemical stability and mechanical strength. This second layer (28) also has electrical resistance characteristics compared to ITO (310.sup.3 .Math.cm), which promote electrical conductivity on the coated glass surface.

    [0057] A third layer (20) corresponds to a material that provides high reflectivity in the infrared region and low absorption in the visible range. This layer is applied over the conductive transparent oxide (28), between 5 and 15 nm thick, preferably between 8 and 10 nm. The use of silver (Ag) is preferred in all examples of this invention because it gives a neutral tone to the coating.

    [0058] A fourth layer (22) consists of an absorbent material that acts as a protective barrier to prevent the oxidation and corrosion of metallic silver during deposition of upper layers and/or glass tempering process. For this purpose, a NiCr alloy (80:20% p/p) is used, however, some examples shown prefer the barrier layer to be partially oxidized (NiCrOx), as this increases the transmission of visible light in the coating. The barrier layer thickness (22) ranges between 0.5 and 5 nm, preferably between 0.5 and 2 nm.

    [0059] A fifth layer (38) of the coating corresponds to a second conductive transparent oxide film, such as AZO. The thickness of this layer (38) is between 8 and 20 nm, preferably between 8 and 15 nm.

    [0060] Finally, in this embodiment, a dielectric material is placed as a protective layer (26). This layer provides mechanical stability, thermal stability, chemical durability and scratch resistance to the entire coating. Materials such as: Si.sub.3N.sub.4, ZrO.sub.2, ZrSiO.sub.2, etc. can be used. This invention uses Si.sub.3N.sub.4 as a protection layer (26), between 10 and 40 nm thick, preferably between 20 and 45 nm.

    Fourth Embodiment (Example 4)

    [0061] In a fourth embodiment of this invention, a low emissivity coating is proposed containing within its structure two functional infrared reflective layers, as shown in FIG. 4.

    [0062] A first dielectric layer (12) is deposited on a glass substrate (10). Silicon nitride (Si.sub.3N.sub.4) can be used between 10 and 40 nm thickness, preferably between 10 and 35 nm. A second layer (14) consists of a metallic oxide with anti-reflective properties such as zinc oxide, between 8 and 20 nm thick, preferably between 8 and 10 nm. A third layer (16) of the coating provides the properties of high reflectivity in the infrared region of the electromagnetic spectrum, characteristics of a low thermal emissivity coating. All examples of this invention use metallic silver as a functional layer, between 5 and 15 nm thick, preferably between 8 and 10 nm, as it provides a neutral tone to the coating. Subsequently, a conductive transparent oxide (18) is applied as a fourth layer, between 50 and 90 nm thick, preferably between 70 and 90 nm. The use of aluminum-doped zinc oxide (AZO) is preferred in this layer because its inclusion enriches the optical, mechanical and conductive properties of coated glass. A fifth layer corresponds to a second functional silver film (26) with high infrared reflectance and 5 to 15 nm thick, preferably between 10 and 15 nm. A sixth layer (30) consists of an absorbent material that acts as a protective barrier and prevents oxidation of metallic silver during deposition of upper layers and/or glass tempering process. For this purpose, a NiCr alloy (80:20% p/p) is used, however, some examples prefer the barrier layer to be partially oxidized (NiCrOx), as this increases the transmission of visible light. The barrier layer thickness (30) ranges between 0.5 and 5 nm, preferably between 1 and 3 nm. A seventh layer (28) corresponds to a second film of aluminum-doped zinc oxide (AZO), is 8 and 30 nm thick, preferably between 8 and 20 nm which increases the coating properties. Finally, in this mode, a dielectric material is placed as a protective layer (22). This layer provides mechanical stability, thermal stability, chemical durability and scratch resistance to the entire coating. Materials such as: Si.sub.3N.sub.4, ZrO.sub.2, ZrSiO.sub.2, etc. can be used. This invention uses Si.sub.3N.sub.4 as a protection layer (22), 10 and 40 nm thick, however, 10 and 25 nm is preferred.

    Fifth Embodiment (Example 5)

    [0063] In a fifth embodiment of this invention, a low emissivity coating includes within its structure two functional infrared reflective layers deposited between films as shown in FIG. 5.

    [0064] A first dielectric layer (12) is deposited on a glass substrate (10), preferably silicon nitride (Si.sub.3N.sub.4), with a thickness between 10 and 40 nm, preferably between 10 and 35 nm.

    [0065] A transparent metal oxide with conductive properties is deposited as a second layer (38) with 8 to 20 nm thick, preferably between 8 and 10 nm. Specifically, in the present invention, aluminum-doped zinc oxide (AZO) is used because this improves light transmission and reflection, chemical stability and mechanical resistance of coated glasses exposed to extreme environmental conditions.

    [0066] A functional layer (16) corresponds to the third layer of the coating, which provides the characteristics of low thermal emissivity. All examples use metallic silver, between 5 and 15 nm thick, preferably between 8 and 10 nm.

    [0067] A fourth layer consists of a second film of conductive transparent oxide (18), with a thickness between 50 and 90 nm, preferably between 70 and 90 nm. aluminum-doped zinc oxide (AZO) is preferentially used because this is a low cost material and also enriches the electrical conductivity properties of coated glass.

    [0068] As a fifth layer, a second metallic silver film (26) is deposited with a thickness between 5 to 15 nm, preferably between 10 and 15 nm, in order to achieve a lower thermal emissivity in the coating.

    [0069] A sixth layer (30) has the function of acting as a barrier to prevent oxidation of silver. In this case a NiCr alloy is used (80:20% p/p) with a thickness of 0.5 to 5 nm, preferably between 1 and 3 nm. However, some examples of this invention prefer this layer is partially oxidized (NiCrOx) in order to increase the transmission of visible light.

    [0070] The penultimate layer (28) of the coating corresponds to a third film of aluminum-doped zinc oxide (AZO), with a thickness between 8 to 30 nm, preferably between 8 and 20 nm. Finally, in this embodiment, a dielectric material is placed as a protection layer (60) to provide mechanical stability, thermal stability and chemical durability to the entire coating. This invention uses Si.sub.3N.sub.4 as a protection layer (22), with a thickness between 10 to 40 nm, however, 10 and 25 nm is preferred.

    Sixth Embodiment (Example 6)

    [0071] In the sixth embodiment of the present invention it consists of arranging layers with low emissivity properties including within their structure two reflective infrared layers deposited between films, as shown in FIG. 6.

    [0072] On a glass substrate (10) a first dielectric layer (12) composed of a first pre-layer (11) with a refractive index between 12 and 1.95 is deposited, on which a second sub-layer (13) of a refractive index between 2.1 and 2.5 is deposited. In this embodiment, first pre-layer (11) is formed by silicon nitride (Si.sub.3N.sub.4), within a thickness of 10 to 40 nm, preferably between 10 and 25 nm, while the second sub-layer (13) of a thickness between 1 to 10 nm and corresponds to an anti-reflective compound with a higher refractive index, e.g. titanium dioxide (TiO.sub.2).

    [0073] A transparent metal oxide (38) with conductive properties is deposited as a second layer between 8 to 20 nm thick, preferably between 8 and 10 nm. Specifically, in the present invention, aluminum-doped zinc oxide (AZO) is used because this improves light transmission and reflection, chemical stability and mechanical resistance of coated glasses exposed to extreme environmental conditions.

    [0074] The functional layer (16) is the third layer of the coating, which provides the characteristics of low thermal emissivity. All examples use metallic silver, between 5 to 15 nm thick, preferably between 8 and 10 nm.

    [0075] A fourth layer (18) consists of a second film of conductive transparent oxide, with a thickness between 50 and 90 nm, preferably between 70 and 90 nm. Aluminum-doped Zinc Oxide (AZO) is preferably used because this is a low cost material and increases electrical conductivity in coated glass.

    [0076] As a fifth layer, a second metallic silver film (26) is deposited within a thickness between a 5 to 15 nm, preferably between 10 and 15 nm, in order to achieve a lower thermal emissivity in the coating.

    [0077] A sixth layer (30) has the function of acting as a barrier to prevent oxidation of silver. A NiCr alloy is used (80:20% p/p) in this case 0.5 to 5 nm thick, preferably between 0.5 and 2 nm. However, some examples of this invention prefer this layer is partially oxidized (NiCrOx) in order to increase the transmission of visible light.

    [0078] A penultimate layer of the coating corresponds to a third film of aluminum-doped zinc oxide (AZO) (28), with a thickness between 8 to 30 nm, preferably between 8 and 20 nm. Finally, in this embodiment, a dielectric material is placed as a protection layer (60) to provide mechanical stability, thermal stability and chemical durability to the entire coating. This invention uses Si.sub.3N.sub.4 as the protection layer (22), with a thickness between 10 to 40 nm, however, 10 and 25 nm is preferred.

    Seventh Embodiment (Example 7)

    [0079] As a seven embodiment of this invention, a low emissivity coating is proposed containing within its structure three functional infrared reflective layers, as shown in FIG. 7.

    [0080] A first dielectric layer (12) of silicon nitride (Si.sub.3N.sub.4) is deposited on a glass substrate (10), within a thickness between 10 and 40 nm, preferably between 30 and 40 nm. A second layer (13) consists of a metallic oxide with anti-reflective properties such as zinc oxide, with a thickness between 8 and 20 nm, preferably between 8 and 15 nm. A third layer (14) of the coating provides the characteristic properties of a low emissivity coating such as a high reflectivity of infrared radiation. All of the examples described metallic silver is used as a functional layer, which is deposited with a thickness between 5 and 15 nm, preferably between 10 and 15 nm. A fourth layer (16) is applied as a transparent conductive oxide within a thickness between 50 and 90 nm, preferably between 70 and 80 nm, because the optical, mechanical and conductive properties of coated glass are enriched. In this invention, the layer is composed of aluminum-doped zinc oxide.

    [0081] A fifth layer (24) corresponds to a second functional silver layer with high infrared reflectance and with a thickness between 5 and 15 nm, preferably between 10 and 15 nm. A sixth layer (26) consists of a second layer of conductive transparent oxide such as AZO, with a thickness between 50 and 90 nm, preferably between 70 and 80 nm. A seventh layer (34) corresponds to a third layer of metallic silver with a thickness between 5 and 15 nm, preferably between 10 and 15 nm, which increases the reflection of infrared radiation and decreases the emissivity of the final product.

    [0082] As an eight layer, an absorbent material (35) is deposited which acts as a protective barrier, in these examples a NiCr alloy is used (80:20% p/p), with a thickness between 0.5 and 5 nm, or preferably between 0.5 and 2 nm. This material prevents oxidation of the metallic silver during the deposition of the upper layers and/or the glass tempering process. To increase visible light transmission, the barrier layer should be partially oxidized (NiCrOx).

    [0083] A ninth layer (36) corresponds to a fourth layer of aluminum-doped zinc oxide (AZO) with a thickness between 20 and 40 nm, preferably between 20 and 30 nm which increases the coating properties. Finally, a tenth layer (22) consists of a dielectric material that provides mechanical stability, thermal stability, chemical durability and scratch resistance to the entire coating. As a protection layer (22), materials such as Si.sub.3N.sub.4, ZrO.sub.2, ZrSiO.sub.2, etc. can be used, however, in the present invention Si.sub.3N.sub.4 is used with a thickness between 10 and 40 nm, preferably between 10 and 25 nm.

    Eight Embodiment (Example 8)

    [0084] As an eight embodiment of this invention, a low emissivity coating is proposed containing within its structure three functional infrared reflective layers, as shown in FIG. 8.

    [0085] A first dielectric layer (12) of silicon nitride (Si.sub.3N.sub.4) is deposited on a glass substrate (10), with a thickness between 10 and 40 nm, preferably between 30 and 40 nm. Starting from previous embodiment (seven), where the second layer (13) consists of ZnO, in this embodiment, this material is replaced by a conductive transparent oxide that increases optical properties, as well as mechanical stability and electrical conductivity of coated glass. In the present invention the layer (14) is composed of aluminum-doped zinc oxide layer (AZO), which is deposited with a thickness between 8 and 20 nm, preferably between 8 and 15 nm. The remaining coating remains the same configuration and composition.

    Ninth Embodiment (Example 9)

    [0086] The ninth embodiment of the present invention comprises a low emissivity coating deposited on a glass substrate. The coating contains within its structure three functional infrared reflective layers, as shown in FIG. 9.

    [0087] A first dielectric layer (12) is deposited on a glass substrate (10), consisting of a first pre-layer (11) of silicon nitride (Si.sub.3N.sub.4), at a thickness between 10 and 40 nm, preferably between 30 and 40 nm, and a second sub-layer (13) of an anti-reflective dielectric material such as TiO.sub.2, deposited with a thickness of 1 to 10 nm. A second layer (15) consists of an anti-reflective material (ZnO) or a conductive transparent oxide (AZO), which help to achieve proper silver growth and increase the coating's optical properties. This second layer (15) has a thickness between 8 and 20 nm, preferably between 8 and 15 nm.

    [0088] A third layer (14) includes a silver metallic layer at a thickness between 5 and 15 nm, preferably between 10 and 15 nm, which acts as an optical filter and reflects most of the infrared radiation. A fourth layer (16) is a transparent conductive oxide which is applied with a thickness between 50 and 90 nm, preferably between 70 and 80 nm, because the optical, mechanical and conductive properties of coated glass are enriched. This invention uses aluminum-doped zinc oxide (AZO).

    [0089] A fifth layer (24) corresponds to a second functional silver layer with high infrared reflectance and a thickness of 5 and 15 nm, preferably between 10 and 15 nm. A sixth layer (26) consists of a layer of conductive transparent oxide such as AZO, at a thickness of 50 and 90 nm, preferably between 70 and 80 nm. A seventh layer (34) corresponds to a third layer of metallic silver at a thickness between 5 and 15 nm, preferably between 10 and 15 nm which increases the reflection of infrared radiation and decreases the emissivity of the final product.

    [0090] As an eighth layer (35) an absorbent material which acts as a protective barrier is deposited, in these examples a NiCr (80:20% p/p) alloy is used at a thickness of 0.5 and 5 nm, preferably between 0.5 and 2 nm. This material prevents oxidation of the metallic silver during the deposition of the upper layers and/or the glass tempering process. To increase visible light transmission, the barrier layer should be partially oxidized (NiCrOx).

    [0091] A ninth layer (36) corresponds to a fourth layer of aluminum-doped zinc oxide (AZO), with a thickness between 20 and 40 nm, preferably between 20 and 30 nm, which increases the coating properties. Finally, a tenth layer (22) consists of a dielectric material that provides mechanical stability, thermal stability, chemical durability and scratch resistance to the entire coating. As a protective layer (22) Si.sub.3N.sub.4 is used at a thickness between 10 and 40 nm, preferably between 10 and 25 nm.

    [0092] On the basis of the examples described above, Table 1 shows the configuration, composition and thickness of the layers composing the above coatings.

    TABLE-US-00001 TABLE 1 Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Thickness Thickness Thickness Thickness Thickness Layer Material (nm) Material (nm) Material (nm) Material (nm) Material (nm) GLASS 1 Si.sub.3N.sub.4 22 Si.sub.3N.sub.4 22 Si.sub.3N.sub.4 10 Si.sub.3N.sub.4 32.5 Si.sub.3N.sub.4 32 2 ZnO 8.5 TiO.sub.2 10 TiO.sub.2 10 ZnO 9 AZO 8.5 3 Ag 10.7 ZnO 8.5 AZO 8.5 Ag 9.6 Ag 8 4 NiCr 1.6 Ag 10.7 Ag 8 AZO 89.5 AZO 85 5 ZnO 11.4 NiCr 1.6 NiCr 1 Ag 13 Ag 13 6 Si.sub.3N.sub.4 43.8 AZO 11.4 AZO 11.4 NiCr 1.1 NiCrOx 2 7 Si.sub.3N.sub.4 22 Si.sub.3N.sub.4 22 AZO 12.6 AZO 12.5 8 Si.sub.3N.sub.4 22.3 Si.sub.3N.sub.4 22 Ex 6 Ex 7 Ex 8 Ex 9 Thickness Thickness Thickness Thickness Layer Material (nm) Material (nm) Material (nm) Material (nm) GLASS 1 Si.sub.3N.sub.4 10 Si.sub.3N.sub.4 36.9 Si.sub.3N.sub.4 35.9 Si.sub.3N.sub.4 35.9 2 TiO.sub.2 10 ZnO 13.1 AZO 13.1 TiO.sub.2 3 3 AZO 8.5 Ag 11 Ag 11 ZnO 13.1 4 Ag 8 AZO 75.8 AZO 78.4 Ag 11 5 AZO 85 Ag 11.6 Ag 11.8 AZO 78.4 6 Ag 13 AZO 76.2 AZO 77.7 Ag 11.8 7 NiCrOx 1.6 Ag 12.6 Ag 12.8 AZO 77.7 8 AZO 12.5 NiCr 0.8 NiCrOx 2 Ag 12.8 9 Si.sub.3N.sub.4 22 AZO 16.8 AZO 16.8 NiCrOx 2 10 Si.sub.3N.sub.4 27.3 Si.sub.3N.sub.4 28.5 AZO 16.8 11 Si.sub.3N.sub.4 28.5

    [0093] Table 2 summarizes the calculated values for the main optical and color properties, before and after heat treating the products at 600 C. for 10 minutes.

    TABLE-US-00002 TABLE 2 LOW-E GLASS SAMPLES FEATURES Features Example 1 Example 2 Example 3 Example 4 Example 5 T.sub.light (%) Before thermal treatment 76.7 78 78.4 70.6 71.8 Transferred color L* 91.3 93.3 93.24 90.2 90 a* 1.5 2.7 1.56 2.8 2.9 b* 4 2 0.58 4.9 1.5 After thermal treatment 79.3 83.7 83.43 76.8 76.3 Transferred color L* 91.3 93.3 93.24 90.2 90 a* 1.8 3 2.74 2.4 3.5 b* 3.6 0.8 0.38 2.9 0.2 R.sub.light (%) - film side Before thermal treatment 6.7 5.7 8 9.6 8.4 Reflected color L* 31.9 28.5 34.08 36.8 34.3 a* 0.2 6.2 0.35 5.4 3.5 b* 19.7 5.1 6.91 11.9 11.1 After thermal treatment 8.7 5.4 7.78 9.8 8.4 Reflected color L* 36.1 27.6 33.4 30.9 34.4 a* 1.7 9.6 5 10.6 1.2 b* 16.4 5.5 2.38 2.6 8.6 T.sub.Sol (%) Before thermal treatment 57.4 54.3 60.3 41.7 39.8 After thermal treatment 58.4 57.3 60.4 43.2 41.4 R.sub.Sun (%) - layer side Before thermal treatment 23.2 27.9 22.3 33.6 39.4 After thermal treatment 25.3 28.3 24.5 37.5 42.2 T.sub.UV (%) Before thermal treatment 44 52.3 55.6 15.4 25.9 After thermal treatment 49 62.8 63.9 30.8 35.4 R.sub.UV (%) - film side Before thermal treatment 23.7 8.1 4.9 11.9 8.1 After thermal treatment 23.7 4.8 5 14.4 10.4 T.sub.IR (%) Before thermal treatment 38.6 29.9 41.4 14.4 9.9 After thermal treatment 38 30.8 36.9 10.9 8.8 R.sub.IR (%) - layer side Before thermal treatment 41.4 53.6 39.5 66.5 76.4 After thermal treatment 43.9 54.2 43.7 74.7 80.1 Emissivity [*] Before thermal treatment 0.079 0.063 0.1 0.03 0.03 After thermal treatment 0.058 0.056 0.09 0.02 0.02 Resistivity (ohm/sq) Before thermal treatment 7.7 6.2 9.4 3.3 2.9 After thermal treatment 5.6 5.4 8.5 2.5 2.2 Features Example 6 Example 7 Example 8 Example 9 T.sub.light (%) Before thermal treatment 66.3 63.2 67.83 66.5 Transferred color L* 87.9 86 88.18 87.9 a* 3.5 5.5 4.42 4.7 b* 1.6 2.7 3.48 3.4 After thermal treatment 71.7 68.4 72.48 71.9 Transferred color L* 87.9 86 88.18 87.9 a* 4.6 4.7 4.95 6.5 b* 2.1 5.4 1.24 0.8 R.sub.light (%) - film side Before thermal treatment 9.6 2.9 3.2 3.1 Reflected color L* 36.7 20.4 20.19 20.7 a* 0.7 4.2 1.34 2.1 b* 16 12.5 4.03 5.1 After thermal treatment 9.8 4 3.55 3.9 Reflected color L* 37.2 24.1 22.2 23.3 a* 1.5 11.1 0.06 4 b* 11 8.3 4.13 4.4 T.sub.Sol (%) Before thermal treatment 36.8 30.1 31 29.9 After thermal treatment 39.7 31.9 32.4 31.6 R.sub.Sun (%) - film side Before thermal treatment 39.2 39.7 41.3 42 After thermal treatment 37.9 43.3 45.5 46.7 T.sub.UV (%) Before thermal treatment 24.2 5.6 9.5 8.5 After thermal treatment 33.5 13.2 13.6 15.8 R.sub.UV (%) - film side Before thermal treatment 7.7 23.4 25.8 26.9 After thermal treatment 7.8 30.4 33.4 33.4 T.sub.IR (%) Before thermal treatment 8.9 3.5 2 1.8 After thermal treatment 10.8 2.8 1.4 1.2 R.sub.IR (%) - film side Before thermal treatment 74.8 80.1 82.5 83 After thermal treatment 69.4 82.6 86.8 87.1 Emissivity [*] Before thermal treatment 0.04 0.024 0.015 0.02 After thermal treatment 0.01 0.016 0.012 0.01 Resistivity (ohm/sq) Before thermal treatment 4.4 2.4 1.6 1.55 After thermal treatment 1.5 1.7 1.3 1.23 *Szczyrbowsky J, et al. New Low emissivity coating. Thin Solid Films 351 (1-2): 254-259. 1999.

    [0094] On the other hand, FIGS. 10 and 11 show the behavior of light transmission and solar transmission in different examples, respectively. As shown, both characteristics increase up to 2% after heat treatment. A reduction in the coating resistivity value of up to one unit is also observed, indicating an improvement in the electrical conductivity properties of the coating. Additionally, the found values reveal that the described configurations have chemical and thermal stability, avoiding the migration of sodium ion from the substrate, the oxidation of silver during the thermal treatment and the possible interpenetration of the layers due to atomic diffusion and temperature.

    [0095] Therefore, it is feasible to apply the products shown in double or triple window systems (annealed, semi-tempered and tempered) aimed at the architectural market, as well as in flat and/or curved laminated glazed systems, with views in residential, architectural and automotive applications.

    [0096] This invention is not limited to the examples shown. Likewise, the coatings described were deposited on clear glass; however, they can be applied on glasses of different chemical composition, shade (gray, bronze, green, blue, etc.) or physical properties, taking into account the changes in the reported characteristics due to the effect of the substrate.