Device and method for forming a coating by pyrolysis

(42) Date of commencement of the patent: 15.11.1998 (45) Date of issue: 25. 6.1999

<td>(30) Priority:</td><td>(73) Patent owner:</td>

<td>11. 1.1993 GB 9300400 claimed.</td><td>GLAVERBEL. B-1170 BRUSSELS (BE).</td>

<td>(56) Documents:</td><td>(72) Inventor:</td>

<td>GB 2156339A US 4900110A</td><td>TERNEU ROBERT THIMEON (BE). FRANCESCHI SECONDO GOSSELIES (BE).</td>

AT 405 279 (54) METHOD AND DEVICE FOR FORMING A COATING BY PYROLYSIS (57) A device is described for pyrolytically forming a coating of metal or metal compound on a surface of a moving hot glass substrate (16). by bringing the surface into contact with a gaseous reagent. The apparatus comprises supporting means (20) for conveying the substrate (16) through a coating chamber (14), an ejection nozzle (10) for the supply and distribution of reagent gas to the coating chamber (14). The ejection nozzle (10) has a gap (12) extending transversely to the path of the substrate (16). The gap (12) opens directly into the coating chamber (14). The longitudinal walls (24) of the gap are practically parallel to each other. The length of the gap (12) is at least equal to the width of the substrate to be coated (16). The inner walls of the ejection nozzle (10) define a continuous convergent path to match the flow of reagent gas with the dimension of the opening of the gap (12), where the convergence angle (a) of the convergence path does not exceed 14 ° at any point coupled to a bogie (47) having U-shaped rollers (48) and cylindrical rollers (50) running on guide rails (49, 51). The device improves the uniformity of the deposition of the coating.

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i-1

DVR 0078018

AT 405 279 Β

The present invention relates to an apparatus for forming a metal coating or coating with a metal compound by pyrolysis on a surface of a moving hot glass substrate, by bringing this surface into contact with a gaseous reagent, the apparatus comprising: support means for conveying the substrate through a coating chamber, Means for supplying and distributing reagent gas to the coating chamber and means for discharging exhaust gas from the coating chamber and a method of forming a coating of metal or metal compound on a moving hot glass substrate by pyrolysis of a reagent in the gaseous phase.

The coating of metal or metal compound formed by pyrolysis on a hot glass substrate is used to alter the apparent coloration of the glass and / or to exhibit other properties necessary against incident radiation, eg the property of reflecting infrared light. For these purposes, a single coating or a multiple coating on the glass substrate may be used. Examples would be coatings of tin oxide SnO2, tin oxide SnO₂ doped with fluorine, titanium dioxide T1O2, titanium nitride TiN, silicon nitride SisN «., Silica S1O2 or SiO_x, Alumina AI2O3, vanadium pentoxide V2O5 or tungsten oxide WO3 or molybdenum oxide MoOa and more generally oxides, sulfides, nitrides or carbides and a layer of two or more of these coatings.

The coating can be formed on a glass sheet moving in a tunnel kiln or on a glass ribbon while it is being formed while it is still hot. The coating may be formed within the annealing leil following the glass ribbon forming device or within the float tank on top of the glass ribbon while the latter is floating in a bath of molten tin.

To form a coating, the substrate is contacted in a coating chamber with a gaseous medium containing one or more gaseous phase substances. The coating chamber is charged with a reagent gas through one or more gaps, the length of which is at least equal to the width to be coated, the gas being supplied through one or more discharge nozzles. Depending on the type of coating to be formed and the reactivity of the substances used, if different substances have to be used, they will be distributed either as a mixture through a single exhaust nozzle into the coating chamber through a nip or separated by different exhaust nozzles across different nips.

Methods and apparatus for forming such a coating are described, for example, in French Patent No. 2,348,166 A (BFG Glass Group) or in French Patent Application No. 2,648,453 A1 (Glaverbel). These methods and devices lead to the formation of particularly strong coatings with advantageous optical properties.

However, it is difficult by this procedure to form coatings that are uniform across the width of the substrate when the substrate is a rough surface, eg like the surface of a strip of float glass moving at a relatively high speed. Then there is a lack of uniformity in the distribution of this coating over the entire surface of the substrate to be coated, which is 2.B. leads to alternating stripes whose visual appearance, especially in reflection, differs either in color or degree of reflection.

The object of the present invention is to improve the uniformity of the deposition of a coating caused by pyrolysis starting from one or more substances in the gaseous phase.

It has been found that these and other advantageous objects can be achieved if the means for distributing the reagent gas to the coating chamber comprise an ejection nozzle having a gap opening which opens directly into the coating chamber with the longitudinal inner walls of the gap being substantially parallel to each other the gap extending transversely to the path of the substrate, the length of the gap is at least substantially equal to the coating width of the substrate (ie the width of the portion of the substrate to be coated) and the inner walls of the ejection nozzle define a continuous converging path to cause the flow of reagent gas to match the dimensions of the opening of the gap and the angle of convergence this convergent path does not exceed a specified limit at any point.

Thus, according to the invention, there is provided an apparatus for forming a coating of metal or metal compound by pyrolysis on a surface of a moving hot glass substrate, by bringing this surface into contact with a gaseous reagent, comprising: support means for conveying the substrate through a coating chamber, Means for supplying and distributing reagent gas to the coating chamber and means for removing waste gas from the coating chamber, characterized, in that the means for distributing reagent gas to the coating chamber comprise an ejection nozzle, which has a gap, located directly in the coating chamber

AT 405 279 B opens, the longitudinal inner walls of the gap being substantially parallel to each other, the gap extends transversely to the path of the substrate, and the length of said gap is at least substantially equal to the coating width of the substrate and wherein the inner walls of the ejection nozzle define a continuous convergent path, to match the flow of reagent gas with the dimension of the opening of the gap, where the convergence angle (a) does not exceed this convergence path 14 at any point.

It was found that, following this condition with respect to the convergence angle of the ejection nozzle inner walls, a uniform flow of reagent gas coincided with the gap opening size, and the distribution of the coating over the surface of the substrate was more uniform and the stripes lighter could be avoided. It is believed that this advantage could be due to the fact that this limitation of the angle promotes the flow of reagent gas in the nozzle in the form of a quasi-laminar flow. It is surprising that a laminar flow in an ejection nozzle promotes the formation of a uniform coating. In fact, firstly, at this point, the reagent gas is not yet in contact with the substrate. Second, especially when multiple reagents are needed to form the layer, turbulence motions are created in the conduits which conduct gas to assist intimate mixing of the gaseous reagent for the purpose of improving its homogeneity to achieve uniform treatment.

European Patent EP-A-365 240 (Pilkington PLC) describes an apparatus for depositing a coating on the surface of a moving belt of hot glass. The apparatus comprises a nozzle in the form of a converging fan-shaped distributor which directs reagent gas to a narrow gap which extends across the width of the glass ribbon to be coated. The reagent gas passes from the inner slot through a restriction to the gas stream before entering the coating chamber. In contrast to this arrangement, the present invention provides that the gap opens directly into the coating chamber. While the arrangement described in EP-A-365,240 may contribute to the formation of a coating in which the general appearance across the width of the glass ribbon is relatively uniform when examined macroscopically, the present invention facilitates a streak-free coating where the uniformity can be confirmed even from a small part to the next small part of the width of the coating.

The continuous convergence path preferably has a convergence angle that does not exceed 9x at any point. This feature allows the deposition of an even more uniform coating. To avoid the need for excessive space, the convergence angle at each point is at least 4 °. This feature facilitates the uniformization of the current across the width of the gap due to the pressure increase caused by a sufficient degree of convergence. In the ideal case, the longitudinal walls of the convergence part of the ejection nozzle form a blunted dihedral whose lower angle is called the convergence angle. This is a simple way by which a regular continuous convergent flow path can be achieved. In one embodiment of the invention, the distribution means comprise at least one spreading device for spreading the stream of gaseous reagent, which provides a divergent path for broadening the flow of reagent gas from its dimensions at the exit from the storage means to a dimension equal to at least part of the length of the gap. This construction promotes the effective distribution of the gas supply to the nozzle. The interior walls of the spreader or devices preferably define a divergence angle that does not exceed 14 x, most preferably not more than 9 'at each point to provide a more even supply to the nozzle.

It has been found that the low divergence prevents the gas flow from being stripped off the walls of the spreader so as to prevent the formation of swirling motions. While the stripping of the gas stream from the walls of the spreader is avoided, compliance with this condition also reduces the risk of forming areas where the flow of reagent gas is nearly stationary. In the case of a highly reactive gas or a gas which is easily decomposed under the action of heat, this could lead to the formation of liquid or solid deposits which easily form defects in the coating.

Preferably, the spreading devices and the nozzle constitute a single component, wherein the spreading devices supply the nozzle with reagent gas. This avoids the need for transition zones between the spreading devices and the nozzle, which could cause a disturbance in the flow of the reactive gas.

Preferably, each of the longitudinal walls of the ejection nozzle forms a single piece with the corresponding wall of the spreader, substantially in the form of truncated ones

AT 405 279 Β triangular triangles are cut to form the spreading devices.

In a preferred embodiment of the invention, the inlet section of each spreading device is circular or rectangular (eg, practically square) and the inlet section is a long one

Rectangle that coincides with at least a part of the inlet cross section of the ejection nozzle or to

Ί 5 fits.

In contrast to the previously proposed arrangements, as shown in FIG. 12 from US-5122 394 A (Lindner / Atochem North America Inc.), in which two reactive gas supply systems are interconnected to coat a substrate of large width, the present invention preferably ensures that that the distribution means comprise a plurality of spreading devices, that are connected to each other io, to distribute the gaseous reagents over the entire length of the nozzle, it being an essential feature of the present invention, that the gap extends over the entire coating width of the substrate. The advantage of this feature is the even supply of reactive gas to a gap of some length. The multiple spreading devices are preferably connected to each other at a distance of at least 10 cm and preferably at least 15 cm from this gap. This spacing avoids that the connections between adjacent feeds can result in loss of uniformity of the coating.

The nozzle terminates in a gap that opens directly into the coating chamber. The gap

- differs from the ejection nozzle and the spreading nozzle in that it has parallel walls. The flow of reactive gas through the gap is believed to be non-laminar, and the advantage of the invention in producing uniform coatings is due to the quasi-laminar flow through the ejection nozzle. While the gap in series, so in line with the ejection nozzle

can also be the use of a gap which is arranged at an angle to the ejection nozzle, or the use of a gap which provides a non-straight path for the gas flow, also possible.

In order to maintain the parallel arrangement of the walls of the gap, braces must be in some

2s intervals are arranged to connect the opposite walls of the gap with each other. To the

To reduce the effect of these struts on the uniformity of the gas flow through the gap, the number of struts should be kept to a minimum, and their profile should be such that they offer only a small resistance to the gas flow. Struts with a cross-section of water-drop type have proven suitable for this purpose.

The longitudinal inner walls of the gap preferably form an angle of between 20 * and 40 'with the plane of movement of the substrate. Preferably, the gap is integral with the nozzle itself.

The gap should have a path for the gas flow of such length sufficient to form a shallow jet of reactive gas entering the coating chamber, depending on the amount

Gas flow. It was found that for a gas flow of 1 m³/ cm gap width / hour a gas flow path in the gap of 40 mm to 200 mm is suitable. The distance between the spa walls preferably has a dimension that is at least six times smaller than the gas flow path in the gap.

The axial plane of the nozzle may be inclined at an angle of between 20 * and 40 'to the plane of movement of the substrate. Preferably, the axial plane of the nozzle is substantially perpendicular to the plane of movement of the substrate to avoid overfilling.

It is difficult to distribute the vapor evenly over long distances. To get a uniform

Coating over the entire width of a glass ribbon (eg about 3 m), it would obviously be possible to have some vapor distribution gaps that are relatively short, eg 70 cm, side by side, so that the entire width of the glass is occupied in this way. However, this leads to significant difficulty because the combination of the gas streams coming from the different columns tai causes defects in the uniformity of the coating deposited on the glass

4 ^ becomes. This problem is solved in embodiments of the present invention by the use of a

· .- solved single gap, which extends over the entire coating width of the glass.

The invention also extends to a process for forming a coating of metal or so metal compound on a moving hot glass substrate by pyrolysis of a reagent in the gaseous phase, which is characterized that a gas stream is formed, by supplying an ejection nozzle, which has a gap opening directly in the coating chamber, the longitudinal inner walls of the gap being substantially parallel to each other, and the gap extends over at least substantially the entire coating width of the substrate with a gaseous medium, i "55 comprises one or more substances in the gaseous phase, a substance or substances, which undergo a chemical reaction or decomposition to form this metal or metal compound on the substrate, and the substrate is brought into contact with this gas stream, which is pushed through this gap and that the convergence angle (a) of the gas flow at each point

AT 405 279 Β is equal to or less than 14 ° along its path within the ejection nozzle.

Two types of devices have been developed which allow the continuous in-line formation of a coating by the pyrolysis of a reagent or vapor phase reagents (CVD) on a hot glass ribbon made by the float process. The two types of coating deposition devices may be referred to as an asymmetric device and a balanced device.

An asymmetrical device has already been described in Patent Specifications GB-1524326-A and GB2033374 A (BFG Glass Group), while a symmetrical device has been described in Patent Specifications GB-2234264 A and GB-2247691 A (Glaverbel).

The devices according to the invention comprise better and improved features compared to those previously described. Both types of devices may be mounted over the glass ribbon after it exits the float tank or over the glass while it is still in the float tank.

They allow virtually the entire width of the glass ribbon, eg, about 3.20 m, to be covered.

These devices can be removable. They can therefore be applied to produce coated glass and, if necessary, taken away.

A system for depositing a layer in a float tank may include means to ensure accurate geometry and even operate at high temperatures prevailing in a float tank. The coating application device can be attached to a running gear or Base be coupled, which has a plurality of rollers, which are adapted to engage in fixed guide beam. In particular, the bogie can run on two guide beams by means of four rollers (IBM 350). These beams may be ribbed with complementary flat locations having a dual purpose of increasing the moment of inertia both vertically and horizontally, and also forming channels in which water circulation may be provided, making it possible to have an identical geometry of the apparatus both at ambient temperature as well as maintain at high temperature. The bogie can by at least one, eg two U-shaped rollers are run, which run on a first guide bar or a rail, while the lateral movements are made possible by at least one, for example two cylindrical rollers running on a second guide bar to compensate for all transverse undulating movements in the raceways ,

Preferably, the apparatus further comprises means for adjusting the height of the coating chamber above the glass substrate. Thus, pistons may be present to adjust the distance between the glass and the roof of the coating chamber to a distance that is generally less than 50 mm (preferably between 3 and 30 mm).

The float tank may be sealed by a bellows system at the point where the device passes.

The apparatus may further comprise means for intercepting litter deposits in the coating chamber, eg one or more metal rods, which are arranged below the vault of the coating chamber. Such a device is the subject of the patent application with the priority of the British patent application no. 9300400.0 from 11. January 1993, filed concurrently, entitled Apparatus and Method for Forming a Pyrolysis Coating and Internal File Reference G 3907.

The invention will now be described with reference to the accompanying drawings in which:

Figure 1 shows a vertical cross section of an asymmetrical device according to the invention;

Figure 1A shows a schematic cross-section along the line I-1 in Figure 1;

Figure 2 is a cross section similar to Figure 1A of an alternative asymmetric device according to the

Erfindu ng, which is suitable for coating a wider glass substrate shows;

Figure 3 shows a detail of a part of the device shown in Figure 2, in the direction III of Figure 2;

Figure 4 shows a vertical cross-section of a symmetrical device according to the invention;

Figure 5 shows a detail of a part of the device shown in Figure 4;

FIG. 6 shows a detail of the same part of the device shown in FIG. 5, seen in FIG

Direction VI of Fig. 5, shows;

Figure 7 shows an alternative embodiment of a part of the device shown in Figure 4;

FIG. 8 shows a detail of the same part of the device as shown in FIG. 7, viewed in FIG

Direction VIII of Fig. 7, shows;

Figure 9 shows in an enlarged view an alternative construction of a part of a device according to the invention, and

Figure 10 is an enlarged view of another alternative construction for a part of a device

AT 405 279 Β according to the invention.

Figures 1 and 1A show an entire asymmetric device comprising three main parts:

(i) two vaporized or gaseous reagent ejection nozzles 10, each 85 cm high, including a gap 12a, 12b, each gap having a gas flow path of 15 cm, an orifice size of 8 mm, and a gap between the gap walls of FIG mm has:

(ii) a coating chamber 14 above the glass 16 which consists of a shallow arch defining a downwardly open channel; and (iii) a gap 18 for withdrawing or venting the vapors used.

The glass ribbon 16 is supported by rollers 20 and driven in the direction shown by arrow A.

The vapor flow in the coating chamber 14 along the glass 16 is controlled mainly by suction.

When a hot reagent needs to be contacted with the glass 16 at a point outside the float tank, the entire device is preferably insulated.

The number of successive Reagenzzuführspalte 12a, b depends on the nature of the coating to be formed. The gaps 12 a, b are inclined in the direction of the coating chamber 14.

Maintaining a uniform flow rate of steam or gas across the width of the substrate is also facilitated by the parallelism of the walls 24 of the inlet gaps 12a, b and the outlet gap 18.

The device may be placed above the glass 16 so that the reagents flow in the direction of movement A of the belt or in the opposite direction.

The gaseous reactant feeders are formed by a feed pipe 22 connected to an adapter 26 leading into the nozzle 10. The longitudinal walls 34 of the converging part of the ejection nozzle 10 form a truncated dihedron 11 whose dihedral angle or convergence angle (a) is 9 ', this convergence angle (a) being determined in the transverse sense of the gap 12a, b. The low convergence angle (a) causes a smooth redistribution of the pressure of the discharge gas flow in a laminar manner without sudden local changes in pressure. This contributes to the uniformity of the coating.

The curvature or roof 38 of the coating chamber 14 is at a distance of 20 mm from the glass 16. The length of the coating chamber 14 is selected so that the reagent remains in contact with the glass 16 for 6 to 10 seconds. In practice, the length of the coating chamber 14 is selected once and for all, according to the most commonly used speed of movement of the glass 16 - eg about 14 m / min. for 4 mm glass - and the concentration of the reagent is adjusted whenever necessary according to the nature and thickness of the coating to be obtained.

The device is sealed by means of carbon fiber seals when the apparatus is in a float tank or by Refrasil® or Cerafelt® skirts, which may be impregnated with boron carbide when the device is located outside the float tank. The device may also be sealed, at least upstream, by the presence of a gas seal (see reference numeral 244 in FIG. 4), which prevents the entry of ambient atmosphere in the coating chamber.

To prevent fouling of the coating chamber 14 by spill deposits that may fall onto the glass 16 and create defects in the coating formed thereon, the apparatus includes a system for intercepting litter deposits. As described in our copending patent application of the same date (referred to above) with the internal reference G 3907. Stainless steel rods 40 are disposed below the camber 38 of the coating chamber 14. These rods preferably collect the solid material that forms over the glass 16 and direct the gas streams away from the arch, which remains clean. The rods move transversely to how the glass 16 moves, making it possible to progressively remove the soiled part and replace it with a clean part. Instead of the transverse bars, it is possible to use a cable that moves in a closed loop. This device is particularly useful in devices using hot reagents.

The device is formed of annealed pieces of metal which are fixed together by bolts rather than by welding to avoid heat distortion.

In the embodiments shown in FIGS. 2 and 3, a plurality of feeders are provided, which are arranged along a gap 112. The special geometry of the feeds distributes the reactive vapor homogeneously along a single gap 112 occupying the entire coating width of a glass ribbon (nearly 3 m long) to uniformly provide the gap with reactive vapors.

The gaseous reactant feed means consists of six circular feed tubes 122 connected to six pyramids 128 leading into the gap 112. The inlet cross section 129

AT 405 279 B each pyramid 128 is a rectangle of 10 cm x 20 cm. To fit the outlet section of the feed tubes 122, adapters 126 are provided. The outlet cross-section of each pyramid 128 represented by the imaginary line 130 is an oblong rectangle that matches a portion of the inlet cross-section of the ejection nozzle 110, as indicated by the imaginary line 132.

The six pyramids 128 form spreading devices whose diverging inner walls 136 define therebetween a diverging angle (β) of 14 ', this divergence angle (β) being determined in the longitudinal sense of the gap 112. The spreaders together with the adapters 126 broaden the flow of reagent gas from its dimension at the exit of the feed tubes 122 to a dimension equal to the length of the gap 112. The pyramids 128 and the adapters 126 together form the distribution means which lead from the supply pipes 122 to the discharge nozzle 110.

The longitudinal walls 134 (see FIG. 3) of the converging portion of the ejection nozzle 110 and the six pyramids 128 form a truncated dihedron 111 whose dihedral angle or convergence angle (a) is 9 ', this convergence angle (a) being determined in the transverse sense of the gap 112. Each longitudinal wall 134 of the ejection nozzle forms a single piece with the corresponding walls of the six pyramids, which is cut in the form of truncated isosceles triangles to form the six pyramids.

The low divergence and convergence angles α, β allow a flow of gas to flow without separation from the walls, and therefore without any whirls, and favor the equalization of pressure.

The supply device makes it possible to change from a plurality of feed tubes 122 having a circular cross-section to a single rectangular cross-section, as has the gap 112.

This device has considerable advantages in that it allows a homogeneous distribution of steam to be achieved without introducing any unnecessary loss of head or areas of stagnation where corrosion of the materials of the device could occur.

The height of the thimble 111, which forms the junction of the six pyramids with the gap 112 (on the order of 20 cm), is chosen to achieve a good compromise between the generation of a uniform current and the size of the device. The height of the spreading device, ie the pyramid 128, is 60 cm.

The delivery of gas through each feed tube 122 may be individually controlled by means of valves 123, which proves useful in controlling the transverse uniformity of the thickness of the coating. In this way, it is possible to account for and compensate for the existence of transverse temperature gradients between the center and the edges of the glass ribbon.

Maintaining a uniform flow rate of vapor or gas across the width of the substrate is also facilitated by the parallelism of the walls 124 of the inlet gaps 112. This parallelism is maintained by the presence of the struts 125 with a profile in the form of a water droplet, which are directed with their widest part upstream against the gas flow. The choice of this geometry reduces or eliminates the formation of a tail of differential pressure downstream from the struts. A strut height of 29 mm and a maximum width of 12 mm has proven to be suitable. It is preferred that the struts 125 be sufficiently far away from the exit of the gap to avoid the formation of streaks on the coating. Preferably, this distance is at least 7 cm. On the other hand, the struts 125 should not be located too far away from the exit of the gap, otherwise they will not provide sufficient rigidity to maintain a constant distance along the length of the gap. Preferably, this distance is less than 15 cm, advantageously between 8 and 12 cm, for example 10 cm. Moreover, a distance between the struts of about 25 cm is used (exaggerated in the figures for clarity).

The introduction of the reagent into its carrier gas occurs at a tubular conduit 122 at a location prior to its connection to the adapter 126. This tube is equipped with Venturi tubes 127a, 127b. At the neck of the first Venturi tube 127 a z. B. Tin chloride SnCl atomizes and this is carried along by the hot nitrogen and the carrier gas / vapor mixture is completed by passing through a second venturi tube 127b. The same applies to the introduction of water vapor into another pipe.

If the device is used to deposit a coating on a glass ribbon when the latter has left the float tank, the entire machine can be placed on a chassis containing the carrier gas heaters and the hot gas manifold tubing with the adapters 126, which feed the gaps 112.

If one wishes to reduce the vertical dimensions of the device, the vertical pyramid system is replaced by pyramids 128, which are inclined to the plane of the substrate in the same plane as the gaps 12a, b in FIG.

AT 405 279 Β

The modification shown in Figure 9 can be fitted in the device of Figure 1 or Figure 3. In this modification, the nozzle 410 has a larger upper convergent portion 460 having an axial plane extending substantially perpendicular to the surface of the substrate to be coated and a smaller lower convergent portion 462 having its axial plane inclined to the coating surface, the walls 464 of the lower convergent part are integral and continuous with the parallel walls 424 of the gap 412. Struts 425 are disposed in the lower convergent portion 462 of the nozzle 410 to maintain the parallel arrangement of the walls 424 across the width of the device.

The modification shown in Figure 10 can be fitted in the device of Figure 1 or 3 Firgur. In this modification, an ejection nozzle 510 has a gap 512 whose axial plane extends in a direction inclined to the coating surface. The gap 512 is formed by parallel side walls 524, each of which includes a step 565 defining an upper nip portion 566 and a lower nip portion 567. In the upper gap part 566, the walls 524 are farther apart than in the lower gap part 567. Struts 525 are disposed in the upper gap portion 566 of the gap 512 to ensure the parallel arrangement of the walls 524 across the entire width of the device.

Examples - Asymmetric

The following examples illustrate the use of an asymmetric device as described in connection with FIGS. 1, 1A, 2 and 3, for example.

This device makes it possible, for example, to apply coatings of tin oxide SnCb, tin oxide SnC 2 doped with fluorine, titanium dioxide TiO 2, titanium nitride TiN, silicon nitride S 13 N 4 and, in general terms, oxides, sulfides, nitrides or carbides.

To form coatings of tin oxide SnC&gt; 2 or titanium dioxide T1O2, two consecutive gaps 112 are used. The reagent with the metal (Sn or Ti) (fed at the first gap

112a) is a tetrachloride, which is liquid at room temperature, and in a stream of anhydrous

Carrier nitrogen gas is evaporated at about 600'C. The evaporation is facilitated by the atomization of these reagents in the carrier gas.

To produce the oxide, the molecules of tetrachloride are brought in the presence of water vapor, which is conducted to the second gap 112b. The water vapor is overheated to about 600 * C and is also injected into a carrier gas which is at about 600'C heated air. For example, SnO2 may be formed using the proportions of SnCl and H2O disclosed in British Patent Specification GB 2026454 (Glaverbel).

In the case of the formation of conductive tin oxide SnO 2, the dopant is fluorine: HF is added to the water vapor. The HF partial pressure is pHF = 0.2 pSnCL. Also, another dopant may be introduced: liquid antimony chloride SbCls, which is mixed directly with the tin chloride SnCL to which it is miscible in any proportion. The presence of antimony chloride SbCls makes it possible to stain the coating of tin oxide SnC&gt; 2, which can then absorb (and reflect) some of the near-infrared solar radiation.

The gas flow rate (carrier gas + reagent) in each gap 112 is 1 m³/ cm gap / hour at the

4o operating temperature.

In order to coat SnO 2 or TiO 2 tin oxide, Inconel 600 or, optionally, an even more refractory alloy (Hastalloy) has been selected for the parts of the device in contact with tin chloride SnCl or titanium chloride TiCL and Monel 400 for the water vapor and HF gap ,

The layer formed is uniform, both when examined macroscopically across the entire width of the coated substrate, and when adjacent zones are tested. The coating is streak-free.

The symmetrical device shown in Figures 4, 5 and 6 comprises a central reagent injection gap 212, on each side of which is a coating chamber 214a, 214b consisting of a channel connected to a suction gap 218a, 218b. This symmetrical device occupies virtually the entire width of the glass 16.

Several features of the device are similar to those described with reference to the asymmetric device of Figures 1, 1A, 2 and 3: injecting reagent into the carrier gas via venturi tubes and maintaining the parallelism of the injection and suction gaps by water droplet aspirations 225th

The symmetrical device shown in Figure 4 is 3 m long and is designed to have no deviation exceeding 1 mm, even in a high temperature environment.

AT 405 279 Β

The device is useful for depositing a coating of reagents that must be kept cool until they come in contact with the hot glass 16. The device includes only a single reagent supply gap 212. It is possible to introduce through this gap 212 a mixture of several reagents which only react with one another when the temperature is sufficiently high, that is to say on the glass 16. The device is constructed of aluminum and provided with cooling lines 242.

This arrangement sits at a height of less than 12 mm above the glass 16, eg 4 mm. The presence of this cooled device disturbs the temperature of the glass 16 only to a very small extent or not at all, since the coating chamber 214a, b consists of a polished aluminum sheet with very low emissivity, which fulfills the role of a thermal mirror.

The device is airtight since gas seals 244 are present upstream and downstream, preventing any exchange between the ambient atmosphere and the coating chamber 214a, b. There are also lateral shields supplemented by suction and a gas seal, especially when it is not possible to use self-lubricating mechanical seals (graphite, boron carbide) (in the case of oxidized layers).

In order to enable deposition of a layer on a glass substrate in a float tank, one must incorporate means that ensure accurate geometry and function even at the high temperatures prevailing in the float tank. Thus, as shown in Fig. 4, the coating deposition apparatus is mounted on a carriage 247 carrying rollers adapted to engage fixed guide rails. In particular, the running position 247 runs by means of four rollers on two guide rails 249, 251 (IPN 350). The bogie 247 is guided by a pair of rollers 248 having U-shaped profiles that run on a first guide bar or rail 249 while permitting lateral movement by a pair of cylindrical rollers 250 running on a second guide rail 251 compensate for any transverse wave motion in the tracks. These rails are rib-shaped with corresponding flat parts having a dual purpose of increasing the moment of inertia in both vertical and horizontal directions and also forming channels in which water circulation can be provided, allowing an identical geometry of the device maintain at ambient temperature as well as at high temperature.

The injection nip 212 of the nozzle 210 is equipped with five adjustable feeds 246 which introduce the vapor into an injection nozzle in the form of a thimble 211 which terminates in the gap 212, the dihedral angle or convergence angle (a) being 9 '. A larger number of adjustable feeders, such as 16, may alternatively be provided. The height of the gap 210 is 20 cm.

The gap 312 may be curved as shown in FIGS. 7 and 8. While this construction can complicate the installation, it can bring the advantage of requiring less space in height when the walls 324 of the gap 312 are horizontally disposed and its feed is perpendicular.

Examples - Symmetrical

The following examples show the use of a symmetrical device as described in connection with FIG.

The device allows the deposition of coatings of silica S1O2 or SiO_x of silane SiH + and oxygen as described in British Patents GB-2234264 A and GB 2247691 A referred to above.

A corresponding device can also be used to form a coating of aluminum oxide Al 2 O 3 from Aluminiumacetylacetonatdampf. In this case, the material in contact with the reagent vapor is stainless steel.

The same type of device can also be used to deposit a metallic carbonyl metal coating.

Such a device may be rebuilt to use reagents that are not allowed to come into contact with each other during their delivery to the glass 16. In this case, two reagent feeds are arranged side by side, each terminating in an inclined gap with its inclination plane converging to the slant plane of the other slit. This device should ideally not be cooled.

For example, several successive devices can be used to deposit coatings on glass while the latter is in the float tank; first silica SiO₂and then vanadium pentoxide V₂Os or tungsten oxide WO3 or molybdenum oxide MoO₃into the sodium in

AT 405 279 B atomic state is converted to convert the oxide into vanadium, tungsten or molybdenum bronze, and finally a tin dioxide SnOj barrier layer is deposited over it. Optionally, the tin oxide SnO 2 barrier may also be deposited on the belt just after it exits the float tank. Such deposits have such electrical conductivity (bronze) that they are reasonably intermediate between precious metals and heavily doped semiconductors. Thus, a glass is obtained which carries a coating which is optically very selective in reflection with a metallic appearance and has a very low solar factor.

The layer formed is uniform, both when examined macroscopically across the entire width of the coated substrate and when adjacent zones are tested. The coating is streak-free.