CH684888A5 - A coated glass. - Google Patents

Description

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CH 684 888 A5

Description

The present invention relates to a glass having a multi-layer coating transmitting light.

Coated glass finds its use in many fields and for different uses. The present invention mainly relates to the application of coatings to glass for sun protection purposes.

The more and more frequent use in architecture of glazed facades imposes certain desiderata that the glass manufacturer must try to satisfy. From the technical point of view, it is often desired that the glazing does not allow too much of the incident solar radiation to pass through so that the interior of the glazed structure is not overheated in sunny weather. However, the glazing must also transmit a reasonable proportion of visible light, in order to allow natural lighting of the interior of the structure, and in order to allow its occupants to see outside.

From an aesthetic point of view, it is sometimes preferred that the entire glass facade of a building has an approximately uniform appearance: it may therefore be desirable for the windows of a building to have characteristics in reflection which, when observed from the outside, are similar to those of the opaque parts of the facade, such as the lighters. In addition, it may be desirable to obtain a particular color of the coated glass when viewed in reflection.

The present invention relates to a glass carrying a multi-layer coating transmitting light, characterized in that said coating successively comprises:

(A) a metal oxide layer ("layer A") containing a material whose refractive index is higher than that of glass;

(B) a layer of metal oxide or silica ("layer B") containing a material whose refractive index is lower than that of the material of layer A; and

(C) a layer (“layer C”) containing a material chosen from chromium, alloys containing chromium, alloys of titanium and aluminum, their nitrides, and nitride of zirconium or titanium.

The three layers act together advantageously for the purpose pursued, and the precise properties obtained can be modified by changing the materials used and the thicknesses of these layers. The third layer cited, layer C, of metal or nitride, is an absorbent layer, and it is above all responsible for lowering the transmission of the coated glass with respect to total solar radiation. Increasing the thickness of layer C will decrease the total energy transmission and at the same time decrease the light transmission. It can also have an effect on the color of the glazing when viewed in reflection. The first two layers mentioned, layers A and B of refractive indices respectively larger and smaller, also modify the light transmission properties of the coated glass. For a given thickness of the layer C, they can be arranged to increase the light transmission, and to increase the color purity of excitation of the reflected light. And this can be done without reducing the total energy reflection of the coated glass; in fact, in certain circumstances, this reflection can be increased. It is therefore possible to reduce the absorption of the energy radiation of the coated glass and to reduce its solar factor. The expression "solar factor" is used to describe the sum of the total energy directly transmitted and the energy which is absorbed and re-radiated by the face distant from the energy source, as a proportion of the total energy radiation. reaching the coated glass. A judicious choice of the position of the layers on the glass relative to the observer and of the thickness of such layers, can also make it possible to reduce the light reflection without increasing the solar factor and / or to obtain a relatively neutral shade.

It is considered particularly advantageous that the use of a multi-layer coating on glass according to the invention offers additional parameters (the materials and the thicknesses of the layers) which can be modified to obtain a good compromise between light transmission. of glass and its solar factor and that it allows a degree of color control in reflection of the coated glass. The use of such coated glass in a building facade can also facilitate the harmonization of the exterior appearance of this facade between parts which are transparent and parts which are opaque.

The sequence of depositing the three layers of the coating on the glass must, according to the invention, be either A, B, C, or C, B, A. The order which one chooses will depend on the manner in which the coated glass will be installed in a building and desired optical properties. By way of example, the optical properties of a coated sheet according to the invention may vary depending on whether the layer A or the layer C is closer to the observer.

In certain preferred embodiments of the invention, said layer A is disposed between said layer C and the glass.

It is conventional to define the different possible positions of a coating on a glass sheet as it is installed in an exterior window frame in the following manner: position 1 is on the exterior face of the exterior sheet or of the single sheet of the window and position 2 is on the inside of this sheet; positions 3 and 4 are respectively the sides facing

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CH 684 888 A5

outside and inward of the second internal panel, if there is one, and so on. In order to obtain the desired appearance in reflection from the exterior of a building, the glass can be installed so that layer A is disposed between layer C and the exterior of the building. Therefore, some preferred embodiments of the invention, in which said layer A is disposed between said layer C and the glass can be installed so that the coating is in position 2. Obviously, a coating consisting of layers A , B, C deposited in reverse order can also be placed in position 2. In both cases, the coating is protected from ambient climatic conditions which could cause premature aging of the coating and deterioration of its properties. Additional protection of the coating against premature aging due to atmospheric pollutants can be offered by incorporating such a coated sheet in a hollow glazing, with the coating disposed inside this glazing. Therefore, contact of the coating with atmospheric pollutants can be hindered, or avoided if the interior of the hollow glazing is sealed.

In general, when layer C consists of chromium or nickel-chromium, or of a chromium nitride, of nickel-chromium, of zirconium or of titanium, this layer can have an atmospheric corrosion resistance which is suitable for all practical cases. However, certain alloys containing chromium, such as stainless steels, have less satisfactory resistance. Therefore, in some of these preferred embodiments of the invention, said layer C is a layer of stainless steel (containing chromium) which is in turn topped with a protective coating of oxide or nitride. There are various oxide or nitride coatings known per se which are hard and durable and which therefore contribute to the resistance to atmospheric corrosion and to abrasion of the coating as a whole and therefore act against premature aging of the coating.

When layer C consists of a nitride, such as titanium nitride, it can be protected by a thin layer of oxide. Therefore, to prevent a layer of titanium nitride from being scratched, a thin layer of titanium oxide or tin oxide can be applied. These protective layers have little influence on the optical properties of the coating as a whole. For example, tin oxide is slightly lubricating and protects the coating from scratches. An oxide coating with a thickness equal to or less than 15 nm is suitable, for example 10 nm of TÌO2 or 15 nm of SnC> 2.

In other preferred embodiments of the invention, said layer C is arranged between said layer A and the glass. A sheet of glass bearing a te! siding can be installed as a building window with the siding in position 1 to achieve the desired appearance in reflection when viewed from the outside of the building. This will mean that the A layer of the coating can be exposed to ambient weather conditions, but there are several high refractive index materials that can be easily deposited to form hard, durable coatings that have sufficient corrosion resistance atmospheric and abrasion for the purposes pursued. A coating having layers deposited in the reverse order can also be in position 1 so that layer C is exposed to ambient climatic conditions. The positioning in 1 of the coating can have certain advantages from the point of view of protection against solar energy. Because layer C of the coating absorbs solar radiation, it will tend to become very hot and even hot when exposed to strong sunlight. The glass sheet which carries it will also be heated. Therefore, the coated sheet can be an important source of infrared radiation. If the coating is in position 1, there will be a slight tendency that such radiation is preferably emitted towards the outside of the building but, more importantly, the face of the coated sheet which occupies position 2 can be provided with a coating which reduces the emissivity of this face with respect to infrared radiation. For example, a coating of doped tin oxide can be placed in position 2. This increases the sun protection effect of the coated glass.

It will obviously be noted that such a low-emissivity coating can advantageously be deposited on a second sheet of hollow glazing which also incorporates a coated glass according to the invention, whether the multilayer coating occupies position 1 or position 2. Such a low emissivity coating could occupy position 3 or position 4.

Preferably, such a layer C consists of titanium nitride. Titanium nitride can also form chemically and mechanically durable layers. In this layer, titanium and nitrogen should not be present in stoichiometric proportions, and it has in fact been found that best results are obtained when there is a stoichiometric excess of titanium, so that the layer can contain free titanium. Such a layer can be easily formed by sputtering of titanium in the presence of nitrogen. The thickness of such a layer of titanium nitride can be precisely controlled and reproducible if produced in this way.

The thickness of layer C has a pronounced effect on the optical properties of the coated glass, in particular with regard to its transmission and its color in reflection. By modifying the thickness of this coating layer, it is possible to obtain a variety of colors in reflection and a range of light transmissions. Preferably, such a layer C of zirconium or titanium nitride has a geometric thickness of between 15 nm and 60 nm. Such layers tend to have a bluish to greenish tint in reflection. Other materials capable of forming a so-called layer C, in this case chromium, alloys containing chromium and their nitrides, can be formed into layers of the coating which have a neutral or gray hue in reflection. The use of titanium and aluminum alloys or their nitrides makes it possible to form coatings of a wide range of colors.

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Because said layer C absorbs incident radiation fairly well and can tend to become quite hot, the glass may be subjected to a certain level of thermal shock which would be unacceptable for safety reasons, unless the glasses are reinforced with a certain way. For this reason, said glass is advantageously tempered glass. The quenching treatment used can be a thermal quenching treatment, or a chemical quenching treatment, as appropriate. In certain cases (for example when the light transmission is high - of the order of 40%), the reduction in the solar factor resulting from certain embodiments of the invention makes it possible to avoid the need to mechanically reinforce the glass by quenching or hardening. Indeed, the modification of the selectivity reduces the absorption in the coating for a given light transmission, and therefore reduces the heating effect of the glazing.

Preferably, said layer A, the layer with a higher refractive index, is a layer consisting essentially of titanium dioxide, zirconium dioxide and / or tin dioxide. A suitable layer of titanium dioxide can be formed with a refractive index of about 2.3 by a sputtering technique well known per se. Zirconium dioxide has a refractive index of 2.1. A coating layer of tin dioxide can be similarly formed, again with a refractive index close to 2. These materials can be formed into high quality layers which are transparent and durable, chemically and mechanically.

As a variant, it is preferable to deposit one or more of these coating layers by pyrolytic route in order to promote resistance to abrasion and corrosion. It is currently envisaged that such a coating layer deposited by pyrolysis can be formed, either directly on the glass, or on a pyrolytic coating layer previously deposited.

Advantageously, said layer A has an optical thickness between 20 nm and 190 nm, and preferably between 30 nm and 100 nm. The effect that such a layer A has on the transmission properties of the energy radiation of the coated glass is thus improved, due to the interference effects.

Preferably, said layer B, the layer of smaller refractive index, is a layer consisting substantially of silicon oxide. The use of silicon oxide is advantageous because it too can be formed into chemically and mechanically durable layers. A suitable silicon oxide layer can be formed by sputtering. Such sputtering can be carried out in the presence of oxygen in an amount such that the adjustment of the oxygen content of the layer which is formed is such that the layer has as low a refractive index as possible, if it is longed for. For example, it is possible to obtain a layer of silicon oxide having a refractive index of approximately 1.4 to 1.45.

Advantageously, said layer B has an optical thickness comprised between 5 nm and 120 nm, and preferably comprised between 5 nm and 60 nm, advantageously between 14 nm and 60 nm. The effect that this layer has on the transmission properties of the energy radiation of the coated glass is thus improved, due to the interference effects.

Certain embodiments of the invention will now be described in more detail, by way of example, and with reference to the appended schematic drawings in which:

Figs. 1 to 3 are each a schematic and detailed cross section of an embodiment of a glazing according to the invention.

In fig. 1, a glass sheet G1 is successively coated with a layer A, a layer B and a layer C which, together, form a multi-layer coating in position 2, that is to say on the inner side of the outer sheet or single sheet of a window. The glass sheet G1 is optionally associated with a second glass sheet G2 to form a hollow glazing which can optionally be hermetically sealed so as to protect the coating A, B, C from contact with the glass. 'ambiant air. Such an optional second glass sheet G2 is shown as carrying an optional coating E in position 3 made of a material which is adapted to reduce the emissivity of the face in position 3 of the glass sheet G2 with respect to the infrared radiation. Because the emissivity is reduced, the reflection is improved, so that the infrared radiation from the first coated glass sheet G1 is reflected back to the outside of the building. Alternatively, such an optional coating E may be applied to the 4-position face of the glass sheet G2 with a similar result, although in this case the second glass sheet G2 will tend to become hotter than if the coating E is in position 3.

In fig. 2, a glass sheet G is successively coated with a layer C, a layer B and a layer A which, together, form a multi-layer coating in position 1. An optional coating E is also deposited on the glass sheet G in position 2 and consists of a material which is adapted to reduce the emissivity of the face in position 2 of the glass sheet G with respect to infrared radiation.

In fig. 3, a glass sheet G is successively coated with a layer A, a layer B and a layer C which, together, form a multi-layer coating in position 2, that is to say on the inner side of the outer sheet or single sheet of a window. The glass sheet G is shown as carrying an optional coating P, also in position 2, of an oxide or a nitride the aim of which is to improve the resistance of the layer C against chemical and / or physical attack. .

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EXAMPLE 1

A ribbon of float glass 6 mm thick, while still hot after leaving a floating enclosure, passes through a coating station where a coating of tin dioxide is formed on the glass by pyrolysis, in a manner known per se, in an optical thickness of between 30 nm and 100 nm to form the layer A. The ribbon is cut into sheets and the sheets are then thermally toughened. Alternatively, precut sheets are pyrolytically coated and, after such coating, the cooling gradient is adjusted so that these sheets are thermally quenched.

A sheet of tempered glass carrying a pyrolytic coating is introduced into a treatment enclosure containing two sources of plane magnetron sputtering having targets in titanium and silicon respectively and provided with an entry airlock and an exit airlock , a conveyor for the substrate, power sources, spray gas inlets and an exhaust port.

The pressure in the enclosure is reduced to 0.15 Pa. The substrate is conveyed in front of the spray sources while the silicon source is activated and sprayed cold with gaseous oxygen under an effective deposition pressure of 0, 2 Pa to give a layer of silicon oxide (a layer B) with a refractive index of 1.4 and an optical thickness of between 10 and 120 nm. The silicon source is then deactivated. As a variant, the source of silicon is constituted by a rotary cathode.

Oxygen is purged from the system and nitrogen is introduced at a pressure of 0.3 Pa as atomizing gas. The titanium source is activated and the substrate is routed in front of it to deposit a layer comprising titanium nitride having a geometric thickness between 15 and 60 nm. In fact, when analyzed later, the "titanium nitride" layer is found to contain a slight stoichiometric excess of titanium.

A sheet of soda-lime glass of ordinary composition 6 mm thick is chemically toughened. Chemical toughening is carried out by bringing the glass into contact with molten potassium nitrate at a temperature of 465 ° C for a period of between two and a half and eight hours to obtain the desired degree of surface compressive stress from 450 to 600 MPa on the surface of the glass. The glass is float glass and, before tempering, it is maintained at a temperature of 465 ° C. for 8 hours to restore the balance of the ionic populations of the opposite surface layers of the glass. As a variant, the glass used is drawn glass 4 mm thick, and this pre-treatment is omitted.

Three coating layers, A, B and C, respectively of titanium dioxide, silicon oxide and titanium nitride, are then applied to the glass. To deposit these layers, the substrate is introduced into a treatment chamber containing two plane magnetron sputtering sources having targets in titanium and silicon respectively, and provided with an entry airlock and an exit airlock, d '' a conveyor for the substrate, power sources, spray gas inlets and a discharge orifice.

The pressure in the enclosure is reduced to 0.15 Pa. The substrate is conveyed in front of the spray sources while the titanium source is activated and sprayed cold with gaseous oxygen in the presence of argon under effective pressure. 0.2 Pa deposit to give a layer of titanium dioxide with a refractive index of 2.3. The titanium source is deactivated and the silicon source is activated. The substrate is routed in front of this source to deposit a layer of silicon oxide with a refractive index of 1.4. The silicon source is then deactivated.

Alternatively, the source of silicon is a rotary cathode. In another variant, the sources of titanium and silicon are activated simultaneously and the substrate is routed in front of them to sequentially deposit the two coating layers there.

Finally, the oxygen is purged from the system and nitrogen is introduced under a pressure of 0.3 Pa as atomizing gas. The titanium source is activated and the substrate is routed in front of it to deposit a layer comprising titanium nitride having a geometric thickness between 15 and 60 nm. In fact, when analyzed later, the "titanium nitride" layer is found to contain a slight stoichiometric excess of titanium.

The thicknesses of the different layers of the coating are as follows:

EXAMPLE 2

Layer A Layer B Layer C

Titanium dioxide Silicon oxide Titanium nitride

th. geometric 35 nm th. geometric 20 nm th. geometric 35 nm

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The result is a glass sheet carrying layers of coating A, B and C successively deposited, as shown in Figs. 1 and 3 of the drawings.

The optical properties of the coated sheet when it is placed in position 2 and viewed from the glass side, are:

Light transmission TL = 25%

Light reflection RL <10%.

The reflected color is purple, with a purity of more than 40%.

EXAMPLES 3 AND 4

In variants of Example 2, the three coating layers are deposited in the same order, namely with the titanium oxide layer adjacent to the glass, but with different thicknesses. These geometric thicknesses and the properties of the various coated sheets are given in the following table 1, the sheets having been coated in position 2 and examined from the glass side:

Table 1

Example 3

Example 4

Thickness TÌO2

25 nm

20 nm

SÌO2 thickness

40 nm

10 nm

TiN thickness

25 nm

25 nm

Light transmission

30%

30%

Light reflection

9%

8%

Solar factor

39%

39%

Neutral purple-purple tint

Dominant wavelength

470 nm

Color purity

44%

3%

Coordinates of Hunter

+7

Hunter's b coordinate

-29

It should be noted that the coated sheet of Example 4 has a light reflection and a color which are close to that of uncoated glass, however with a relatively low solar factor.

EXAMPLE 5

As a variant of Example 2, the three coating layers have the same thicknesses but are deposited in reverse order on one face of a glass sheet.

The sheet thus coated offers a solar factor of 34% with its uncoated side facing the energy source and it has the following properties when viewed from its uncoated side:

Light reflection RL = 28%

Light transmission TL = 30%

Hunter coordinates a = 0, b = 14

Reflective tint: golden yellow with a dominant wavelength of 575 nm and an excitation color purity of 28%.

In order to obtain the same light transmission of 30% using only a coating layer of titanium nitride on the glass, this coating layer should be formed in the same way but in a thickness of 23 nm, and it would offer a reflection 13% bright. However, its solar factor would be 38% and its hue would be blue with an excitation color purity of 19%. Therefore, by adopting this example of the invention, the solar factor and the ratio of light transmission to the solar factor are improved and the color is altered.

If a single coating layer of titanium nitride were formed in the same way in the same thickness of 35 nm, the light transmission would be reduced to only 20% with a light reflection of 20% and a solar factor of 31%. The hue would again be blue, with an excitation color purity of 13%. Again, the ratio of light transmission to the solar factor is improved and the color is altered.

As a variant of this example, the other face of the glass sheet carries a coating layer with low emissivity deposited by pyrolysis so as to obtain a coated sheet as illustrated in FIG. 2 of the drawings.

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EXAMPLES 6 TO 8

As a variant of Example 5, the three coating layers are deposited in the same order, namely with the titanium nitride adjacent to the glass, but in different thicknesses. These geometric thicknesses and the properties of the various coated sheets are given in the following table 2, with two comparative examples, Comp A and Comp B. The solar factor is measured with the uncoated side of the glass sheet facing the source of energy, and the optical properties are considered from the uncoated side of the sheet.

Table 2

Ex. 6

Ex. 7

Ex. 8

Comp A

Comp B

TiN thickness

50 nm

20 nm

20 nm

15 nm

35 nm

SÌO2 thickness

25 nm

35 nm

15 nm

0

0

Thickness TÌO2

20 nm

35 nm

15 nm

0

0

Light transmission

20%

40%

40%

40%

40%

Light reflection

25%

23%

22%

8%

20%

Solar factor

28%

43%

42%

47%

31%

Tint yellow gold yellow gold blue blue blue

Long, dominant wave

576 nm

576 nm

482 nm

478 nm

478 nm

Color purity

21%

37%

19%

21%

13%

Coordinates of Hunter

0

0

-3.5

0

-2

Hunter's b coordinate

+10.5

+16

+11

-8.5

-7

EXAMPLES 9 TO 12

In variants of Example 2, the treatment enclosure contains an additional source of planar magnetron sputtering which is activated to deposit a layer C having a geometric thickness of between 15 nm and 60 nm.

In Example 9, this additional source is made of stainless steel and the source is activated in an argon atmosphere under a pressure of 0.3 Pa to form a layer C of light-transmitting stainless steel. In this example, the stainless steel layer is the first layer deposited on the glass sheet.

The thicknesses of the different layers of the coating are as follows:

Layer C Stainless steel th. geometric 5 nm Layer B Silicon oxide th. geometric 30 nm Layer A Titanium dioxide th. geometric 30 nm

The sheet thus coated offers a solar factor of 53% with its uncoated side facing the energy source and it has the following optical properties when viewed from its uncoated side:

Light reflection RL = 33%

Light transmission TL = 48%

Reflective tint: yellowish gray with an excitation color purity of 7%.

Such a coated sheet can be compared with a sheet which has a two-layer coating of stainless steel (5 nm) and titanium dioxide (10 nm) which offers a somewhat similar factor, in fact 51%. Such a sheet has the following optical properties when viewed from its uncoated side:

Light reflection RL = 13%

Light transmission TL = 37%

Reflective tint: bluish gray with an excitation color purity of 10%.

In a variant of Example 9, the stainless steel is sprayed in the presence of nitrogen under a pressure of 0.3 Pa to form a coating layer of "stainless steel nitride". This does not have a great effect on the energy transmission properties of the coated sheet, but it has been noted that the corrosion resistance of the coating is improved.

In Example 10, the additional source is chromium, and the source is activated in an argon atmosphere under a pressure of 0.3 Pa to form a layer C of chromium transmitting the

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light. As a variant of this example 10, the chromium is sprayed in the presence of nitrogen under a pressure of 0.3 Pa to form a coating layer of chromium nitride.

In Example 11, the additional source is of chromenickel alloy, and the source is activated in an argon atmosphere under a pressure of 0.3 Pa to form a layer C of chromium-nickel alloy transmitting light. As a variant of this example 11, the chromium-nickel alloy is sprayed in the presence of nitrogen under a pressure of 0.3 Pa to form a coating layer of "chromium-nickel nitride". In another variant of Example 11, zirconium is sprayed in the presence of nitrogen under a pressure of 0.3 Pa to form a coating layer of zirconium nitride.

In Example 12, the additional source is made of titanium-aluminum alloy, and the source is activated in an argon atmosphere under a pressure of 0.3 Pa to form a layer C of titanium-aluminum alloy transmitting light. As a variant of this example 12, the titanium-aluminum alloy is sprayed in the presence of nitrogen under a pressure of 0.3 Pa to form a coating layer of “titanium-aluminum nitride”.

EXAMPLE 13

Alternatively, four coating layers are deposited with a layer of titanium oxide adjacent to the glass.

The thicknesses and materials of the different layers of the coating are as follows:

Layer A

Titanium dioxide

th. geometric

20 nm

Layer B

Silicon oxide

th. geometric

20 nm

Layer C

Stainless steel

th. geometric

6 nm and

Titanium nitride

th. geometric

15 nm.

The sheet thus coated offers a solar factor of 29% from its coated side and it has the following optical properties when viewed from its coated side:

Light reflection RL = 44%

Light transmission TL = 23%

Tint in reflection: none noticeable. The sheet has an excitation color purity of 1%. EXAMPLES 14 AND 15

In variants of Example 5, the three coating layers are deposited in the same order, namely with the titanium nitride adjacent to the glass. The geometric thicknesses and the properties of the various coated sheets are given in Table 3 below, the optical properties being those which are observed from the coated face.

Table 3

Ex. 14

Ex. 15

Comp A

Comp B

TiN thickness

35 nm

35 nm

15 nm

35 nm

SÌO2 thickness

20 nm

40 nm

0

0

Thickness TÌO2

35 nm

40 nm

0

0

Light transmission

30%

20%

40%

20%

Light reflection

5%

35%

22%

35%

Solar factor

36%

33%

42%

26%

Hue purple blue blue blue-green

Color purity

76%

32%

10%

5%

Long, dominant wave

470 nm

478 nm

476 nm

481 nm

Coordinates of Hunter

+17

-2

0

0

Hunter's b coordinate

-65

-30

-7

-3.5

EXAMPLES 16 TO 20

The other examples in Table 4 below are prepared in the same manner as that described with respect to Example 5, except that in Examples 18 and 19, the coating layers are removed.

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posed by pyrolysis using a method well known per se in the art, rather than sputtering.

Table 4

Ex. 16

Ex. 17

Ex. 18

Ex. 19

Ex. 20

Thickness Ti02 (A)

55 nm

25 nm

30 nm

20 nm

10 nm

Thickness SiO2 (B)

30 nm

10 nm

70 nm

80 nm

60 nm

TiN thickness (C)

23 nm

35 nm

23 nm

23 nm

15 nm

Coating order

CBA

ABC

ABC

CBA

ABC

Observed side glass glass glass layer layer

Light transmission

28%

24%

26%

31%

42%

Light reflection

17%

7%

26%

27%

22%

Solar factor

39%

35%

37%

40%

43%

Neutral gold shade blue blue neutral

Long, dominant wave

589 nm

477 nm

477 nm

Color purity

33%

1%

32%

36%

1%

Coordinates of Hunter

+10

0

-0.5

Hunter's b coordinate

+11.5

-26

-31.4

Claims (13)

Claims 1. Glass carrying a multi-layer coating transmitting light, characterized in that said coating successively comprises: (A) a metal oxide layer ("b layer A") containing a material whose refractive index is higher than that of glass; (B) a layer of metal oxide or silica ("layer B") containing a material whose refractive index is lower than that of the material of layer A; and (C) a layer (“layer C”) containing a material chosen from chromium, alloys containing chromium, alloys of titanium and aluminum, their nitrides, and nitride of zirconium or titanium. 2. Glass carrying a coating according to claim 1, characterized in that layer A is disposed between said layer C and the glass. 3. Glass bearing a coating according to claim 2, characterized in that the layer C is a layer of stainless steel containing chromium which is in turn surmounted by a protective coating of oxide or nitride. 4. Glass carrying a coating according to claim 1, characterized in that layer C is disposed between said layer A and the glass. 5. Glass carrying a coating according to one of claims 1, 2 and 4, characterized in that the layer C is a layer of titanium nitride. 6. Glass carrying a coating according to claim 5, characterized in that the layer C has a geometric thickness between 15 nm and 60 nm. 7. Glass carrying a coating according to one of claims 1 to 6, characterized in that the glass is tempered glass. 8. Glass carrying a coating according to one of claims 1 to 7, characterized in that said layer A is a layer consisting substantially of titanium dioxide, zirconium dioxide and / or tin dioxide. 9. Glass carrying a coating according to one of claims 1 to 8, characterized in that said layer A has an optical thickness between 20 nm and 190 nm. 10. Glass carrying a coating according to claim 9, characterized in that said layer A has an optical thickness between 30 nm and 100 nm. 11. Glass carrying a coating according to one of claims 1 to 10, characterized in that said layer B is a layer consisting substantially of silicon oxide. 12. Glass carrying a coating according to one of claims 1 to 11, characterized in that said layer B has an optical thickness between 5 nm and 120 nm. 13. Glass carrying a coating according to claim 12, characterized in that b said layer B has an optical thickness between 14 nm and 60 nm. 9