GB2262749A - Light-transmitting multi-layer coated glass - Google Patents

Description

COATED GLASS 2262749 This invention relates to glass bearing a

light-transmitting multilayer coating.

Coated glass finds use in various fields for various purposes. The present invention is principally concerned with the application of coatings to glass for solar screening purposes.

-The extensive architectural use of glazed facades imposes certain desiderata which the glass manufacturer must try to meet. From the technical point of view, it is often.d.,sired that the glazing shall not pass too great a proportion of total incident solar radiation in order that the interior of the glazed structure shall not become overheated during sunny weather. However, the glazing must also transmit a reasonable proportion of visible light, in order to allow natural illumination of the interior of the structure, and in order to allow its occupants to see out.

From the aesthetic pAnt of view, it is sometimes preferred that the whole of a glazed facade of a building shall present an approximately uniform appearance: thus it may be desirable that the windows of a building should be given reflection characteristics which, when viewed from the exterior, are similar to those of opaque parts of the facade such as window basements. Furthermore, it may be desirable to achieve a particular colour for the coated glass when viewed in reflection.

According to-the present invention, there is provided glass bearing a light-transmitting multi-layer coating, characterised in that said coating comprises, in succession:

SolarTiN 4111@ (A) a metal oxide layer ("the A layer") containing a material with higher refractive index than the glass; 0989B (B) a metal oxide or silica layer ("the B layer") containing a material with lower refractive index than the material of the A layer; and (C) a layer ("the C layer") containing a material selected from chromium, chromium-containing alloys, titanium aluminium alloys, nitrides thereof, and zirconium or titanium nitride.

The three coating layers act together in a beneficial way for the purposes in view, and the precise properties obtained can be varied by altering the materials used and the thicknesses of those layers. The third layer mentioned, the C layer, of metal or nitride, is an absorbent layer, and it is primarily responsible for cutting the transmissivity of the coated glass in respect of total solar radiation. Increasing the thickness of that C layer will decrease the total energy transmissilvity and will at the same time, diminish the luminous transmissivity. It may also have an effect on the colour of the glass when' viewed in reflection. The first two 1 layers mentioned, the A and B layers of respectively higher and lower refractive index, also modify the light transmission properties of the coated glass. For a given thickness of the C layer, they can be arranged to increase the luminous transmission, and to increase the purity of the colour of excitation of reflected light. And this can be done without reducing the total energy reflectivity of the coated glass; in fact in some circumstances, that reflectivity may be increased. Thus it is possible to reduce the absorption'of radiant energy by the coated glass and to reduce its solar factor. We use the expression "solar factor,, to denote the sum of the total energy directly transmitted and the energy which is absorbed and re-radiated on the side away from the energy source, as a proportion of the total 1 SolarTiN 4111@ 0989B radiant energy incident on the coated glass. A judicious choice of the positioning of the coatings on the glass relative to the observer and the thickness of such coatings, may also enable one to reduce the luminous reflectivity without adding to the solar factor and/or obtaining a relatively neutral colour.

It is considered a particularly important advantage that the use of a multi-layer coating on glass according to the invention affords additional parameters (the materials and thicknesses of the layers) which may be altered to achieve a very good compromise between the luminous transmission of the glass and its solar factor, and also that it allows a degree of control of the colour of the coated glass in reflection. Thus the use of such coated glass in a building facade can also facilitate matching of the external appearance of that facade as between parts which are transparent and parts which are opaque.

The sequence of deposition of the three coating layers on the glass must, in accordance with the invention be either A,B,C, or C,B,A. Which of these orders is chosen will depend on the way in which the coated glass is to be installed in a building and on the optical properties which are desired. By way of example, the optical properties of a sheet coated in accordance with this invention may vary depending on whether the A layer or the c layer is closer to the observer.

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

It is a convention to define various possible positions for a coating on a glass sheet as installed in an external window frame of a building in the following way: position 1 is at the exterior face of the exterior or only sheet of the window and position 2 is the interior face of that sheet; positions SolarTiN 4111@ 0989B 3 and 4 are respectively the exterior and interior faces of the next pane in, if any, and so on. In order to achieve the desired aspect in reflection from the outside of the building, the glass may be installed so that the A layer is between the C layer and the exterior of the building. Thus, such preferred embodiments of the invention in which said A layer is located between said C layer and the glass may be installed so that the coating is in position 2. Of course a coating formed by A, B, and C, layers deposited in the reverse order could also be located in position 2. In either case, the coating is protected from exposure to ambient weather conditions which might cause premature ageing of the coating and a deterioration of its properties. Further protection of the coating against premature ageing due to atmospheric pollutants may be afforded by incorporating such a coated sheet into a hollow glazing panel with the coating at the interior of that panel. Thus contact between the coating and any atmospheric pollutants may be hindered, or prevented if the interior of the hollow panel is sealed.

In general, when the C layer is made from chromium or nickelchromium, or a nitride bf chromium, nickel-chromium, zirconium or titanium, lthat layer can have a resistance to atmospheric corrosion which is adequate for all practical purposes. However, certain chromium-containing alloys such as stainless steels have a less satisfactory resistance. In some such preferred embodiments of the invention, therefore, said C layer is a (chromium-containing) stainless steel layer which is in turn over-coated with a protective coating of an oxide or nitride. There are various oxide and nitride coatings which are known per se which are hard and durable and thus contribute to the resistance of the coating as a whole to atmospheric corrosion and abrasion and thus militate against premature ageing of the coating.

When the C layer is made from a nitride, such as titanium SolarTiN 4111@ 0989B - 5 nitride, this may be protected by a thin layer of oxide. Thus, in order to avoid a titanium nitride layer becoming scratched, a fine coating of titanium oxide or tin oxide may be applied. These protective layers have little influence upon the optical properties of the coating as a whole. For example, tin oxide is mildly lubricating and protects the coating against scratching. An oxide coating of less than 15= is convenient, such as lOnm Ti02 or 15 nm Sn02.

In other preferred embodiments of the invention, said C layer is located between said A layer and the glass. A glass sheet bearing such a coating may be installed as a window of a building with the coating in position 1 in order to achieve the desired aspect in reflection when viewed from outside the building. This will admittedly mean that the A layer of the coating may be exposed to ambient weather conditions, but there are several materials of high refractive index which may readily be deposited to form hard and durable coatings which have sufficient resistance to atmospheric corrosion and to abrasion for the purposes in view. A coating having layers deposited in the reverse order could also be located in position 1 so that'the C layer was exposed to ambient weather conditions. Arranging the coating in position I can have certain advantages from the point of view of screening of solar energy. Because the C layer of the coating is absorbent of solar radiation it will tend to become quite warm or even hot during exposure to strong sunlight. The supporting glass sheet will also be heated. As a consequence the coated sheet may be a source of significant infrared radiation. If the coating is in position 1 there may be a slight tendency for such radiation to be preferentially emitted towards the exterior of the building, but more importantly, the face of the coated sheet which occupies position 2 may be provided with a coating which reduces the emissivity of that face in respect of infra-red radiation. For example a doped tin oxide coating may be provided in SolarTiN 4111@ 0989B - 6 position 2. This enhances the solar screening effect of the coated glass.

It will of course be appreciated that such a low-emissivity coating may be provided with advantage on a second sheet of a hollow glazing panel which also incorporates a sheet coated in accordance with this invention, whether that multi-layer coating occupies position 1 or position 2. Such a lowemissivity coating would then occupy position 3 or position 4.

Preferably, such C layer is of titanium nitride. Titanium nitride can also be formed into chemically and mechanically durable layers. In that layer, the titanium and nitrogen need not be present in stoichiometric proportions, indeed we have found that the best results are obtained when there is a stoichiometric excess of titanium so that the layer possibly contains some free titanium. Such a layer may readily be formed by sputtering titanium in the presence of nitrogen. The thickness of such a titanium nitride layer may be controlled accurately and reproducibly by forming it in that way.

The thickness of such C layer has a marked effect on the optical properties of the coated glass, in particular as regards its transmissivity and its colour in reflection. By varying the thickness of that coating layer it is possible to achieve a variety of colours in reflection and a range of luminous transmissivities. Preferably, such a C layer of zirconium or titanium nitride has a geometrical thickness in the range 15 nm to 60 nm. Such layers tend to have a blue to greenish tint in reflection. other materials suitable forming a said C layer, namely chromium, chromium-containing alloys and nitrides thereof, can be formed into layers of coatings which have a neutral or grey tint in reflection. The use of titanium aluminium alloys or nitrides thereof SolarTiN 4111@ allows a large range of coating colours to be formed.

0989B Because the said C layer is rather absorptive of incident radiation and may tend to get quite hot, the glass could be subjected to a degree of thermal shock which would be unacceptable for safety reasons unless the glasses were reinforced in some way. Advantageously, therefore, said glass is tempered glass. The tempering treatment used may be a thermal tempering treatment, or a chemical tempering treatment as convenient. In certain cases (such as where the luminous transmissivity is high - in the order of 40%), the reduction of the solar factor which results from certain embodiments of the invention, allows one to avoid the need for mechanical reinforcement of the glass by tempering or hardening. In effect, the modification of the selectivity reduces the absorption in the coating for a given luminous transmission, and reduces therefore also the heating effect on the glass.

Preferably, said A layer, the layer with higher refractive index, is a layer substantially consisting of titanium dioxide, zirconium o>ilde and/or tin dioxide. A suitable titanium dioxide layer may 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 tin dioxide coating layer may be formed in a similar way, again with a refractive index close to 2. Both these materials may be formed into high quality layers which are transparent and chemically and mechanically durable.

Alternatively, it may be preferred to deposit one or more such coatinglayers pyrolytically in order to promote abrasion and corrosion resistance. It is presently envisaged that such a pyrolytically deposited coating layer will be formed either directly on the glass or onto a previously deposited pyrolytic coating layer.

SolarTiN 4111@ 0989B Advantageously, said A layer has an optical thickness in the range 20= to 190nm, and preferably in the range 30nm to 10Onm. The effect which that A layer has on the radiant energy transmission properties of the coated glass is thereby enhanced due to interference effects.

Preferably. said B layer, the layer with lower refractive index, is a layer substantially consisting 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 may be formed by sputtering. Such sputtering may be performed in the presence of oxygen in such an amount as to regulate the oxygen content of the layer which is formed so that that layer has a refractive index as low as possible when that is desired. For example it is possible to obtain a silicon oxide layer having a refractive index of about 1.4 to 1.45.

Advantageously, said B layer has an optical thickness in the range 5= to 120nm, and preferably in the range 5 to 60nm, i most preferably 14= to%"60nm. The effect which that layer has on the radiant energy transmission properties of the coated glass is also thereby enhanced due to interference effects.

Certain preferred embodiments of the invention will now be described in greater detail, by way of example, and with reference to the accompanying diagrammatic drawings in which:

Figures 1 to 3 are each a detail and diagrammatic crosssectional view of an embodiment of glass panel in accordance with this invention.

SolarTiN 4111@ 0989B - 9 In Figure 1, a glass sheet G1 is successively coated with an A layer, a B layer and a C layer which together form a multi layer coating in position 2, that is, on the interior face of the exterior or only sheet of a window. The glass sheet G1 is optionally associated with a second glass sheet G2 to form a hollow panel unit which may optionally be hermetically sealed so as to protect the coating A, B, C from contact with ambient air. Such optional second glass sheet G2 is shown as bearing an optional coating E in position 3 of a material which is adapted to reduce the emissivity of the position 3 face of the glass sheet G2 in respect of infra-red radiation. Because emissivity is reduced, reflectivity is enhanced, so infra-red radiation emanating from the first coated glass sheet G1 is reflected back towards the exterior of the building. As a variant, such an optional coating E may be applied to the position 4 face of the glass sheet G2 with a similar result, though in this case the second sheet G2 will tend to become hotter than if that coating E was in position 3.

In Figure 2, a sheet of glass G is successively coated with a X C layer, a B layer anh an A layer which together form a multi-layer coating in position 1. An optional coating E is also provided on the glass sheet G in position 2 and is of a material which is adapted to reduce the emissivity of the position 2 face of the glass sheet G in respect of infra-red radiation.

In Figure 3, a glass sheet G is successively coated with an A layer, a B layer and a C layer which together form a multilayer coating in position 2, that is, on the interior face of the exterior or only sheet of a window. The glass sheet G is shown as bearing an optional coating P, also in position 2, of an oxide or nitride whose purpose is to enhance the resistance of the C layer to chemical and/or physical attack.

SolarTiN 4111@ EXAMPLE 1

0989B - A ribbon of float glass 6mm in thickness was passed through a coating station while it was still hot after leaving a float chamber, and a tin dioxide coating was formed on the glass by pyrolysis in a manner known per se, to an optical thickness of between 30 and 100nm to serve as an A layer. The ribbon was cut into sheets and the sheets were then thermally tempered. In a variant, pre-cut sheets of glass were pyrolytically coated and after such coating, the cooling schedule was arranged so that such sheets became thermally tempered.

A sheet of tempered pyrolytically-coated glass was introduced into a processing chamber containing two planar magnetron sputtering sources having targets respectively of titanium and silicon, and provided with entry and outlet gas-locks, a conveyor for the substrate, power sources, sputtering gas inlets and an evacuation outlet.

The pressure in the chamber was reduced to 0.15 Pa. The substrate was transporeed past the sputtering sources with the silicon source activated and cold sputtered by oxygen gas at an effective depositing pressure of 0. 2 Pa to give a silicon oxide layer (a B layer) with a refractive index of 1.4 and an optical thickness of between 10 and 120 nm, whereafter the silicon source was deactivated. In a variant, the silicon source was constituted as a rotating cathode.

oxygen was purged from the system and nitrogen was introduced at a pressure of 0.3 Pa as sputtering gas. The titanium source was activated and the substrate transported past it to deposit a layer comprising titanium nitride having a geometrical thickness of between 15 and 60 nm. In fact when later analysed, this "titanium nitride" layer was found to contain a slight stoichiometric excess of titanium.

SolarTiN 4111@ EXAMPLE 2

0989B A sheet of alkali-lime glass of ordinary composition with a thickness of 6mm was chemically tempered. The chemical tempering was effected by placing the glass in contact with molten potassium nitrate at a temperature of 4650C for between two and a half hours and eight hours in order to achieve the desired degree of compressive surface stress of 450 to 600 MPa in the surface of the glass. The glass was float glass, and prior to tempering it was maintained at a temperature of 4650C for a period of 8 hours to re-establish equilibrium of the ionic populations of opposite surface layers of the glass. In a variant, the glass used was drawn glass 4mm in thickness, and this pre-treatment was omitted.

Three coating layers, A, B, and C, respectively of titanium dioxide, silicon oxide and titanium nitride, were then applied to the glass. In order to deposit these layers, the substrate was introduced into a processing chamber containing two planar magnetron sputtering sources having targets respectively of titanium and silicon, and provided with entry and outlet gas-locks, a conveyor for the substrate, power sources, sputtering gas inlets and an evacuation outlet.

The pressure in the chamber was reduced to 0.15 Pa. The substrate was transported past the sputtering sources with the titanium source activated and cold sputtered by oxygen gas in the presence of argon at an effective depositing pressure of 0.2 Pa to give a titanium dioxide layer with a refractive index of 2.3. The titanium source was deactivated and the silicon source was activated, and the substrate was transported back past that source to deposit a silicon oxide layer with a refractive index of 1.4, whereafter the silicon source was deactivated.

SolarTiN 4111@ In a variant, the silicon source was constituted as a rotating cathode. In a further variant, the titanium and silicon sources were activated simultaneously and the substrate was transported past them for the sequential deposition of the two coating layers.

0989B Finally, oxygen was purged from the system and nitrogen was introduced at a pressure of 0.3 Pa as sputtering gas. The titanium source was re- activated and the substrate transported past it to deposit a layer comprising titanium nitride having a geometrical thickness of between 15 nm and 60 nm. In fact when later analysed, this "titanium nitride" layer was found to contain a slight stoichiometric excess of titanium.

The thicknesses of the three coating layers were as follows:

Layer A - titanium dioxide - geometrical thickness 35= Layer B - silicon oxide - geometrical thickness 20nm Layer C - titanium nitride geometrical thickness 35nm.

1 The result was a sheet of glass bearing successively deposited coating layers A, B, and C as illustrated in Figures 1 and 3 of the drawings.

The optical properties of the coated sheet when located in position 2, viewed from the glass side, were Luminous transmission = 25% Luminous reflection <10-00 The reflected colour was purple with a purity of more than 40%.

SolarTiN 4111@ EXAMPLES 3 and 4 0989B 13 - In variants of Example 2, the three coating layers were deposited in the same order, namely with the titanium oxide coating adjacent the glass, but to different thicknesses. Those geometrical 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

Ex. 3 Ex. 4 Thickness Ti02 25= 20nm Thickness Si02 40nm lOnm Thickness TiN 25nra 25= Luminous transmission 30-0. 30% Luminous reflection 9% 8% Solar factor 39-0t 39% Tint violet-purple neutral Dominant wavelength 470= Colour purity 44% 3% Hunter coordinate a +7 Hunter coordinate b -29 It should be noted that the coated sheet of Example 4 has a luminous reflection and colour which is close to that of uncoated glass, yet with a relatively low solar factor.

EXAMPLE 5

In a variant of Example 2, the three coating layers were deposited to-the same thicknesses, but in reverse order onto a face of a sheet of glass.

The thus coated sheet afforded a solar factor of 34% with the uncoated side towards the energy source, and it had the SolarTiN 4111@ 0989B 14 following optical properties when viewed from the uncoated side.

Luminous reflection RL = 28% Luminous transmission TL = 30% Hunter coordinates a = 0, b = 14 Tint in reflection: golden yellow with a dominant wavelength of 575 nm and a purity of colour excitation of 28%.

In order to achieve the same luminous transmission of 30% using only a titanium nitride coating layer on the glass, that coating layer could be formed in the same way but to a thickness of 23nm, and it would afford a luminous reflection of 13%. However its solar factor would be 38%, and its tint would be blue with a purity of colour excitation of 19%. Thus by adopting this example of the invention, the solar factor and the ratio of the luminous transmission to the solar factor are improved and the colour is altered.

If a sole coating layer of titanium nitride was formed in the i same way to the same 3Am thickness, the luminous transmission would be reduced to only 20% with a luminous reflection of 20% and a solar factor of 31%. Also, the tint would again be blue, but with a purity of colour excitation of 13-0o. Again, the ratio of the luminous transmission to the solar factor is improved and the colour is altered.

In a variant of this Example, the other face of the sheet of glass bore a pyrolytically formed low emissivity coating layer on its other face so that the result was a coated sheet as illustrated-in Figure 2 of the drawings.

SolarTiN 4111@ EXAMPLES 6 to 8 0989B In variants of Example 5, the three coating layers were deposited in the same order, namely with the titanium nitride adjacent the glass, but to different thicknesses. Those geometrical thicknesses and the properties of the various coated sheets are given in the following Table 2, together with two comparative examples, Comp. A and Comp. B. The solar factor is measured with the uncoated face of the glass sheet towards the energy source, and the optical properties are as viewed from the uncoated face of the sheet.

TABLE 2

Ex. 6 Ex. 7 Ex. 8 COMP. A Comp. B Thickness TiN 50nm 20nm 20nm 15nm 35nm Thickness Si02 25nm 35nm 15nm -0- -0 Thickness Ti02 20nm 35nm 15nm -0- -0 Luminous transmission 20% 40% 40% 40% 20% Luminous reflection 5% 23% 22% 8% 20% Solar factor 28% 43% 42% 47% 31% Tint golden- golden- blue blue blue yellow yellow Dominant wavelength 576nm 576nm 482nm 478nm 478nm Colour purity 21-0. 37-0o 19-0. 21-0o 13-0.

Hunter coordinate a 0 0 -3.5 0 -2 Hunter coordinate b +10. 5 +16 +11 -8.5 -7 EXAMPLES 9 to 12 In variants of Example 2, the processing chamber contained an additional planar magnetron sputtering source which was activated for the deposition of a layer C having a SolarTiN 4111@ 16 geometrical thickness of between 15 nm and 60 nm.

0989B In Example 9, that additional source was of stainless steel, and that source was activated in an argon atmosphere at a pressure of 0.3Pa for the formation of a light transmitting layer C of stainless steel. In this Example, the stainless steel layer was the first layer deposited on the glass sheet.

The thicknesses of the three coating layers were as follows:

Layer C - stainless steel - geometrical thickness -Irjnm Layer B - silicon oxide - geometrical thickness 30nm Layer A - titanium dioxide geometrical thickness 30nm.

The thus coated sheet afforded a solar factor of 53% with its uncoated face towards the energy source, and it had the following optical properties when viewed from the uncoated side.

Luminous reflection RL = 33% Luminous transmission TL = 48% Tint in reflection: yellowish grey with a purity of colour excitation of 7%.

Such a coated sheet may be compared with a sheet which bears a two layer coating of stainless steel (5nm) and titanium dioxide (ionm) which affords a somewhat similar solar factor of, in fact, 51%. Such a sheet has the following optical properties when viewed from the uncoated side.

Luminous reflection RL = 13% Luminous transmission TL = 37% Tint in reflection: bluish grey with a purity of colour excitation of lot.

SolarTiN 4111@ 0989B 17 In a variant of Example 9, the stainless steel was sputtered in the presence of nitrogen at a pressure of 0.3Pa to form a "stainless steel nitride" coating layer. This did not have any great effect on the energy transmitting properties of the coated sheet, but it was noted that the corrosion resistance of the coating was improved.

In Example 10, that additional source was of chromium, and that source was activated in an argon atmosphere at a pressure of 0.3Pa for the formation of a lght transmitting layer C of chromium. In a variant of Example 10, the chromium was sputtered in the presence of nitrogen at a pressure of 0.3Pa to form a chromium nitride coating layer.

In Example 11, that additional source was of a nickel chromium alloy, and that source was activated in an argon atmosphere at a pressure of 0.3Pa for the formation of a light transmitting layer C of nickel chromium alloy. In a variant of Example 11, the nickel chromium alloy was sputtered in the presence of nitrogen at a pressure of 0.3Pa to form a "nickel chrbmium nitride" coating layer. In a further variant of Example 11, zirconium was sputtered in the presence of nitrogen at a pressure of 0.3Pa to form a zirconium nitride layer.

In Example 12, that additional source was of a titanium aluminium alloy, and that source was activated in an argon atmosphere at a pressure of 0. 3Pa for the formation of a light transmitting layer C of titanium aluminium alloy. In a variant of Example 12, the titanium aluminium alloy was sputtered in the presence of nitrogen at a pressure of 0.3Pa to form a "titanium aluminium nitride', coating layer.

SolarTiN 4111@ EXAMPLE 13

In a variant, four coating layers were deposited with a titanium oxide coating adjacent the glass. 0989B The thicknesses and materials of the four coating layers were as

follows:

Layer A - titanium dioxide - geometrical thickness 20nm Layer B - silicon oxide - geometrical thickness 20nm Layer C - stainless steel - geometrical thickness 6nm, and - titanium nitride - geometrical thickness 15nm.

The thus coated sheet afforded a solar factor of 29% from the coated side, and it had the following optical properties when viewed from the coated side.

Luminous reflection RL = 44% Luminous transmission TL = 23% Tint in reflection: none perceptible. The sheet had a purity of excitation of 1%. - EXAMPLES 14 and 15 In variants of Example 5, the three coating layers were deposited in the same order, namely with the titanium nitride adjacent the glass. Those geometrical thicknesses and the properties of the various coated sheets are given in the following Table 3, the optical properties being those as viewed from the coated side.

SolarTiN 4111@ 0989B TABLE 3 Ex. 14 Ex. 15 Comp. A COMP. B Thickness TiN 35nm 35nm 15nm 35nm Thickness Si02 20nm 40nm -0- -0 Thickness Ti02 35mm 40nm -0- -0 Luminous transmission 30% 20% 40% 20% Luminous reflection 5% 35% 22% 35% Solar factor 36% 33% 42% 26% Tint purple blue blue blueColour purity Dominant wavelength Hunter co-ordinate a Hunter co-ordinate b EXAMPLES 16 to 20 76% 470nm +17 -2 3 2 -'.

478= green 10% 5% 476nm 481nm 0 0 -3.5 The further examples in the following Table 4 were prepared in the same manner as described in connection with Example 5, except that in Examples 18 and 19 the coating layers were deposited by pyrolysis using the method well know in the art, rather than by cathodIc sputtering.

SolarTiN 4111@ 0989B - 20 TABLE 4 Ex. 16 Ex. 17 Ex. 18 Ex. 19 Ex. 2 0 Thickness:

Ti02 (A) 55nn 25nm 30nm 20nm lOnm Si02 (B) 3 Onm, lOnm 70nm 8Onra 6 Onm TiN (C) 23= 3 5= 23= 2 3 nin 15= coating order CBA ABC ABC CBA ABC Viewed side glass glass glass coating coating Luminous transmission 28-0. 24-0. 26-0. 31-0. 42-0o Luminous reflection 17%, 7% 26-0. 27% 22% Solar factor 39% 35% 37% 40-0o 43-0o Tint Golden Neutral Blue Blue Neutral Dominant wavelength 589= - 477= 477nm Purity 33% 150-1 32% 36% 1% Hunter co-ordinate a +10 0 -0.5 Hunter co-ordinate b +11.5 -26 -31.4 SolarTiN 4111@ 0989B - 21

Claims (13)

1. Glass bearing a light-transmitting multi-layer coating, characterised in that said coating comprises, in succession: (A) a metal oxide layer ("the A layer") containing a material with higher refractive index than the glass; (B) a metal oxide or silica layer ("the B layer") containing a material with lower refractive index than the material of the A layer; and C) a layer ("the C layer") containing a material selected from chromium, chromium-containing alloys, titanium aluminium alloys, nitrides thereof, and zirconium or titanium nitride.

2. Coated glass according to claim 1, wherein said A layer is located between said C layer and the glass.

3. Coated glass according to claim 2, wherein said C layer is a (chromiumcontaining) stainless steel layer which is in turn over-coated with a protective coating of an oxide or nitride.

4. Coated glass ac-,ording to claim 1, wherein said C layer is located between said A layer and the glass.

5. Coated glass according to any of claims 1, 2 and 4, wherein said C layer is of titanium nitride.

6. Coated glass according to claim 5, wherein said C layer has a geometrical thickness in the range 15 nm to 60 nm.

7. Coated glass according to any preceding claim, wherein said glass is tempered glass.

SolarTiN 4111@ 0989B

8. Coated glass according to any preceding claim, wherein said A layer is a layer substantially consisting of titanium dioxide, zirconium dioxide and/or tin dioxide.

9. Coated glass according to any preceding claim, wherein said A layer has an optical thickness in the range 20nm to 190nm.

10. Coated glass according to any preceding claim, wherein said A layer has an optical thickness in the range 30nra to 10Onm.

11. Coated glass according to any preceding claim, wherein said B layer is a layer substantially consisting of silicon oxide.

12. Coated glass according to any preceding claim, wherein said B layer has an optical thickness in the range 5nm to 120nm.

13. Coated glass according to claim 12, wherein said B i layer has an optical thIckness in the range 14nin to 60nm.