Device and method for forming a coating by pyrolysis

(54) (56) (57)

PATENT INVENTOR INVENTOR'S OFFICE NAME

CALLED PUBLICATIONS:

Glaverbel, Brussels BE

Robert Terneu, Thimeon BE, Secondo Franceschi, Gosselies BE Albihns Patentbyrå Stockholm AB

Device and method for forming a coating on a glass substrate by pyrolysis

EP Al 0 365 240 (C03C 17/00)

SUMMARY:

and means for discharging exhaust gas from coatings (14). The discharge nozzle (10) has one which extends transversely over the substrate (16) (12) opening directly into the coating chamber (14).

An apparatus is described for the formation by pyrolysis of a metal or metal compound coating on a surface of a hot glass substrate (16) by contacting the surface with a gaseous reagent. The device comprises support means (20) for transporting the substrate (16) through a coating chamber (14), an outflow nozzle (10) for supplying and distributing reagent gas to the coating chamber (14), passage (12), path. The gap

The longitudinal inner walls (24) of the gap are substantially parallel to each other. The length of the gap (12) is at least equal to the width of the substrate (16) to be coated. The inner wall r of the outflow nozzle (10) limits a continuous convergent path to cause the flow of the reagent gas to correspond to the aperture dimension of the gap 12, the convergence angle (a) of the convergent path not exceeding 14 'at any point. The device is coupled to a bogie (47) supporting U-shaped rollers (48) and cylindrical rollers (50) running on guide beams (49, 51). The device improves the deposition uniformity of the coating.

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508 197

The present invention relates to a device for forming, by pyrolysis, a coating of metal or metal compound on a surface of a hot glass substrate by contacting the surface with a gaseous reagent, comprising support means for transporting the substrate through a coating chamber, apparatus for supplying and distributing reagent gas to the coating chamber; and apparatus for discharging exhaust gas from the coating chamber and means for forming a coating of metal or metal compound on a hot glass substrate by pyrolysis of a reagent in the gas phase.

The coating of metal or metal compound formed on a hot glass substrate by pyrolysis is used to modify the visible color of the glass and / or to exhibit other properties required with respect to incident radiation, such as the property of reflecting infrared. A simple coating on the glass substrate can be used for these ends! or a multilayer coating. Examples would be tin oxide SnO coatings₂, tin oxide SnO₂ doped with fluorine, titanium dioxide TiO₂, titanium nitride TiN, silicon nitride Si₃N₄, silica SiO₂ or SiO_x, alumina A1₂O₃, vanadium pentoxide V₂O₅or tungsten oxide WO₃ or molybdenum oxide Mo0₃, and generally oxides, sulfides, nitrides or carbides and a coating of two or more of these coatings.

The coating may be formed on a sheet of glass moving in a tunnel oven or a glass band during formation, while the process is hot. The coating may be formed in a cooling channel which follows the glass band forming device or within the float water on the upper surface of the glass band while the latter flows on a bath of molten tin.

To form the coating, the substrate is contacted in a coating chamber with a gaseous medium comprising

508 197 one or more substances in the gas phase. The coating chamber is fed with a reagent gas through one or more slots, the length of which is at least equal to the width to be coated, discharged through one or more outflow nozzles. Depending on the type of coating to be formed and the reactivity of the substances used, if several substances have to be used, these are distributed either in the form of a mixture through a single discharge nozzle in the coating chamber via a slot or separately through several outflow nozzles via separate slots.

Methods and devices for forming such a coating are described, for example, in French Patent No. 2,348,166 (BFG Glassgroup) 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 technique to form coatings that are uniform across the width of the substrate, with the substrate being a large surface such as the surface of a float glass band moving at a relatively high velocity. A lack of uniformity is then found in the distribution of this coating over the entire surface of the substrate to be coated, which results, for example, in alternating strokes whose visible appearance, mainly in reflection, differs either in color or in the degree of reflection.

The object of the present invention is to improve the uniformity of the deposit in a coating made by pyrolysis based on one or more substances in the gas phase.

We have found that this and other advantageous objects can be achieved when the apparatus for distributing reagent gas to the coating chamber comprises an outflow nozzle provided with a gap opening into the coating chamber, the longitudinal inner walls of the gap being substantially parallel to one another. the gap extends across the path of the substrate, the length of the gap at least substantially

508 197 equals the coating width of the substrate (i.e., the width of the portion of the substrate desired to be coated), and the inner walls of the outflow nozzle limit a continuous convergent path to cause the reagent gas flow to correspond to the dimension of the gap opening, the angle of convergence of that path exceeds a specified limit at any point.

Thus, according to the invention, an apparatus for forming, by pyrolysis, a coating of metal or metal compound on a surface of a hot glass substrate by contacting the surface with a gaseous reagent, comprising support means for transporting the substrate through a coating chamber, is contemplated. apparatus for supplying and distributing reagent gas to the coating chamber and apparatus for discharging exhaust gas from the coating chamber and characterized in that the apparatus for distributing reagent gas to the coating chamber comprises a discharge nozzle provided with a gap which opens directly into the coating chamber; wherein the longitudinal inner walls of the gap are substantially parallel to each other and the gap extends across the path of the substrate and the length of the gap is at least substantially equal to the coating width of the substrate and that the internal nozzle of the outflow nozzle limits a continuous convergent path to bring the gas to the reactor. correspond to the opening dimension of the gap, wherein the convergence angle (a) of the convergent path does not exceed 14 at any point.

It was found that by meeting this condition with respect to the convergence of the inner walls of the effluent nozzle brought a uniform flow of reagent gas into conformity with the dimension of the gap opening and the distribution of the coating over the surface of the substrate was more uniform and the strips could be more easily avoided. It is believed that this advantage could be due to the fact that this angular limitation aids the flow of reagent gas in the nozzle to a form of semi-laminar flow. Surprisingly, a laminar flow in an outflow nozzle supports the formation of a uniform coating. In fact, the first is that of this

508 The 197 point reagent gas is not yet in contact with the substrate. Second, mainly when multiple reagents are required to form the layer, turbulence motions are created in the gas-conducting conduits to help create an intimate mixture of the gas reagents in order to improve its homogeneity so that uniform treatment is achieved.

European patent specification EP-A-365 240 (Pilkington PLC) discloses an apparatus for depositing a coating on the surface of a moving glass band. The device comprises a nozzle in the form of a converging solar spring distributor, which directs reactant gas to a narrow gap extending across the width of the glass strip to be coated. The reactant gas passes from the narrow gap through a gas flow restrictor prior to entry into the coating chamber. In contrast to this arrangement, the present invention relates to the gap opening directly into the coating chamber. While the arrangement described in EP 365 240 may contribute to the formation of a coating whose general appearance is relatively uniform across the width of the glass band, when examined in a macroscopic manner, a streak-free coating, wherein the uniformity may also be confirmed from a small portion to the next small portion on the width of the coating, is facilitated by the preparations of the present invention.

The continuous converging path preferably has an angle of convergence that does not exceed 9 "at any point. This feature allows the deposition of a more uniform coating. To avoid the need for excessive space, the angle of convergence is at least 4 'at some point. This feature facilitates flow uniformity across the width of the gap, thanks to the increase in pressure caused by a sufficient degree of convergence. Ideally, the longitudinal walls of the convergent portion of the effluent nozzle form a truncated V, where the V-shape angle constitutes the said convergence angle. This is a simple way by which a smooth, continuously convergent flow path can be achieved.

508 197

In one embodiment of the invention, the dispensing device comprises at least one dispensing device for spreading the flow of gaseous reagent which limits a divergent path to expand the flow of reagent gas from its dimension upon exit from the delivery device to a dimension equal to at least part of the gap. length. This construction favors the efficient distribution of the gas supply to the nozzle. The inner walls of the spreading device or spreading devices preferably limit a divergence angle not exceeding 14 *, most preferably not more than 9 'at any point to achieve a uniform feed to the nozzle.

We have found that the low divergence prevents the gas flow from spreading from the walls of the diffuser and thus prevents the formation of swirling movements. While avoiding the diffusion of the gas flow from the walls of the diffuser, in accordance with this condition, the risk of formation of areas where the flow of the reagent gas is almost stationary also decreases. In the case of a highly reactive gas or one which is easily decomposable under the influence of heat, this could lead to the formation of liquid or solid deposits, prone to forming defects in the coating.

Preferably, the diffusers and nozzle are a single component, the diffusers providing reagent gas for the nozzle. This avoids the need for transition zones between the diffusers and the nozzle which can cause a disturbance in the flow of the reactive gas.

Preferably, each of the longitudinal walls of the outflow nozzle forms a single piece with a corresponding wall on the spreading device which is cut off substantially in the form of truncated equilateral triangles to form the spreading devices.

In a preferred embodiment of the invention, the inlet cross section of each diffuser is circular or rectangular (such as substantially square) and the exit cross section is a longitudinally extending rectangle which fits at least part of the entry cross section of the outflow nozzle.

Contrary to previously proposed arrangements as shown in FIG. 12 In US Patent US 5,122,394 (Lindner / Atochem North America Inc.) in which two reactive gas delivery systems are interconnected to coat a large-width substrate, the present invention preferably relates to the dispensing device comprising multiple spreader devices interconnected to disperse the gaseous reagents over the entire length of the nozzle, where it is 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 uniform feed of reactive gas to a gap of a certain length. The plurality of spreading devices are preferably connected to each other at a distance of at least 10 cm and preferably at least 15 cm from the gap. This distance avoids that the joints between adjacent feeds could cause a loss in the uniformity of the coating.

The nozzle ends in a slot that opens directly into the coating chamber. The gap differs from the outflow nozzle and spreading device by having parallel walls. The reactive gas flow through the gap is assumed to be non-laminar, with the advantage of the invention expressed in the preparation of uniform coatings being derived from the quasi-laminar flow through the effluent nozzle. While the gap may be in line with the outflow nozzle, the use of a gap is also provided at an angle to the outflow nozzle or the use of a gap which provides a non-direct gas flow path is also possible. To assist in maintaining the parallel disposition of the gap walls, strands may be located at intervals spaced from each other which bind opposing walls into the gap. To reduce the impact of these aspirations on gas flow uniformity through the gap, the number of aspirations should be kept to a minimum and their profiles should be such that they

508 197 offers low resistance to gas flow. Strands having a cross-section of "water drop" shape have been found to be suitable for this purpose.

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

The gap should have a gas flow path of such length as is sufficient to form a flat jet of reactive gas entering the coating chamber depending on the gas flow rate. We have found that a gas flow rate of 1 m³/ cm gap width / h, or a gas flow path in the gap of from 40 mm to 200 mm is suitable. The distance between the tap walls preferably has a dimension that is at least 6 times smaller than the gas flow path in the tap.

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 congestion.

It is difficult to distribute steam uniformly over large distances. In order to deposit a uniform coating over the entire width of a glass band (eg about 3 m) it would obviously be possible to place several vapor distribution slits, each quite short in length, eg 70 cm side by side so as to record this set the entire width of the glass. However, this presents a major difficulty since the association of the gas flows coming from different slots causes defects in the uniformity of the coating deposited on the glass. This problem is solved in embodiments of the present invention by using a single slot extending over the entire coating width of the glass.

The invention also extends to a method of forming a metal or metal compound coating on a hot glass substrate by pyrolysis of a reagent in the gas phase, and is characterized by the gas flow being formed by adding a

508 An outflow nozzle having a gap opening directly in the coating chamber, the longitudinal inner walls of the gap being substantially parallel to each other and the gap extending at least substantially over the entire coating width of the substrate, with a gas medium comprising one or more substances in the gas phase; a substance or substances undergoing a chemical reaction or decomposition to form the metal or metal compound on the substrate and the substrate is contacted with the gas flow exiting through the gap and that at some point along the path of the gas flow convergence into the effluent nozzle is equal with or less than 14 °.

Two types of installations have been developed which allow the continuous in-line formation of a coating by pyrolysis of a reagent or vapors (Chemical Vapor Deposition) (CVD) on a hot glass band made by the float process. The two types of installation for depositing a coating can be described as an asymmetrical installation and a symmetrical installation.

An asymmetric installation has already been described in patent specifications GB 1,524,326 and GB 2,033,374 (BFG Glassgroup), while a symmetrical installation is described in patent specifications GB 2,234,264 and GB 2,247,691 (Glaverbel).

The installations according to the invention include better and improved features compared to those previously described. Both types of installation can be placed above the glass band after it exits from the float water or over the glass while it is still in the float water.

They essentially allow the entire width of the glass band, eg about 3.2 m to be covered.

These installations can be removable. They can therefore be positioned to produce coated glass and removed whenever necessary.

508 197

A system for depositing a layer in a float water can include apparatus for ensuring accurate geometry and functioning even at the high temperatures prevailing in a float water. Thus, the deposition device can be coupled to a bogie which carries a plurality of rollers adapted to engage fixed guide beams. In particular, the bogie can be run by four rollers on two steering axles (IPN 350). These beams can be ribbed with complementary flat iron, which has a dual purpose: to increase the moment of inertia, both vertically and horizontally, and also constitute channels in which water circulation can be arranged, which makes it possible to maintain an identical geometry of the device both at ambient temperature and at high temperatures. temperature. The bogie may be guided by at least one, such as two U-shaped rollers running on a first guide beam or rails, while lateral movements may be enabled by at least one, such as two cylindrical rollers running on a second guide beam to compensate for some transverse wave movements in the running tracks.

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

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

The device may further comprise means for intercepting litter deposits in the coating chamber, for example one or more metal bars arranged under the vault of the coating chamber. Such a device is subject to our co-pending patent application with priority from British Patent Application No. 9300400.0 of January 11, 1993 filed the same day as this application, titled Device and Methods of Forming a Coating by Pyrolysis.

508 197

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

Fig. 1 shows in vertical cross-section an asymmetric installation according to the invention;

Fig. 1A is a sectional view taken along line II of Fig. 1; Fig. 2 is a cross-section similar to Fig. 1A of an alternative asymmetric installation according to the invention, suitable for coating a wider glass substrate;

Fig. 3 is a detail of a portion of the installation shown in Fig. 2 seen in direction III of Fig. 2;

Fig. 4 is a vertical cross section showing a symmetrical installation according to the invention;

Fig. 5 is a detail of part of the installation shown in Fig. 4;

Fig. 6 shows a detail of the same part of the installation as shown in Fig. 5 seen in the direction IV in Fig. 5:

Fig. 7 shows an alternative embodiment of part of the installation shown in Fig. 4;

Fig. 8 shows a detail of the same part of the installation as in Fig. 7 as seen in the direction VIII in Fig. 7;

Fig. 9 in enlarged section shows an alternative construction for part of an installation according to the invention, and Fig. 10 shows in enlarged section a further constructive alternative for part of an installation according to the invention.

Figures 1 and 1A show the whole of an asymmetric installation comprising three main parts:

(i) two evaporative or gaseous reagent effluent nozzles 10, each with a height of 85 cm and including a gap 12a, 12b, each gap having a gas flow path of 15 cm, an aperture dimension of 8 mm and a distance between the walls of the gap of 4 mm;

(ii) a coating chamber 14 consisting of a flat arch which limits a channel open to the bottom above the glass 16 and

508 (Iii) a slot 18 for drawing out the used vapors.

The glass band is supported by rollers 20 and driven in the direction indicated by arrow A.

The flow of vapors in the coating chamber 14 along the glass 16 is controlled mainly by vacuum.

Since hot reagents must be contacted with the glass 16 at a point located outside the float water, the entire installation is preferably insulated.

The number of consecutive reagent delivery slots 12a, b depends on the nature of the coating to be formed. These slots 12a, b are inclined to the coating chamber 14.

Maintaining uniform flow rate of steam or gas across the width of the substrate is also facilitated by the parallelism of the walls 24 in the input slots 12a, b and the extension slit 18.

The device may be placed over the glass 16 so that the reagents flow in the direction of the movement of the strip or in the opposite direction.

The gaseous reactant supply devices are comprised of supply line 22 connected to an adapter 26 which leads into the nozzle 10. The longitudinal walls 34 of the convergent portion of the outlet nozzle 10 form a truncated V 11 whose angle or convergence angle (a) is 9 ', this angle of convergence (a) is determined in the direction across the gap 12a, b.

The small angle of convergence (a) causes an even redistribution of pressure in the exhaust gas stream in a laminar manner without any sudden local variation in pressure. This contributes to the uniformity of the coating.

508 197

The vault or ceiling 38 of the coating chamber 14 is 20 mm from the glass 16. The length of the coating chamber 14 is chosen so that the reagent remains in contact with the glass 16 for about three seconds. In practice, the length of the coating chamber 14 is chosen once and for all according to the most common rate of movement of the glass 16 - ie about 14 m / minute for glass 4 mm thick - and the reagent concentration is adjusted whenever necessary according to the nature and thickness of the coating to be obtained.

The installation is sealed by carbon fiber joints when the installation is located in a float water or by Refrasil (trademark) or Cerafelt (trademark) skirts, possibly impregnated with boron carbide, when the installation is located outside the float water. The installation can also be sealed at least upstream by the presence of a gas joint (compare references 244 in FIG. 4) which prevents the entry of ambient atmosphere into the coating chamber.

In order to prevent contamination of the coating chamber 14 by litter deposits which may fall on the glass 16 and create defects in the coating formed thereon, the installation includes a system for collecting litter deposits, as described in our filed application filed on the same day as the present one, mentioned above. . Metal bars 40 made of stainless steel are provided under the arches of the coating chamber 14. These rods preferably collect the solid material formed above the glass 16 and divert the gas streams away from the vault, which remains clean. The rods move transversely as the glass 16 is transported, thus making it possible to pull away the soiled portion progressively and replace it with a clean portion. Instead of transverse rods, it is possible to use a rope moving in a closed circuit. This device is particularly useful in installations that use hot reagents.

The installation is formed of annealed metal pieces attached to each other by bolts rather than welding to avoid heat distortion.

508 197

In the embodiment shown in Figs. 2 and 3, several feeds are provided along a gap 112. The particular geometry of the feeds distributes the reactive steam homogeneously along a single gap 112 which occupies the entire width of the glass band (almost 3 m long) to supply the gap evenly. with reactive vapors.

The feed device for the gaseous reactants consists of six circular delivery lines 122 connected to six pyramids 128 leading to the gap 112. The entrance cross section 129 of each pyramid 128 is rectangular 10 cm by 20 cm. To fit the output cross section on the feed lines 122, there are transition pieces 126. The exit cross section of each pyramid 128 indicated by the imaginary line 130 is a longitudinal elongate rectangle that fits a portion of the entry cross section of the outflow nozzle 110, indicated by the imaginary line 132.

The six pyramids 128 are scattering devices whose divergent inner walls 136 between them limit a divergence angle (/ 3) of 14 ", this divergence angle (0) being determined in the longitudinal direction of the gap 112. The diffusers together with the fitting pieces 126 extend the flow of the reagent gas from its dimension upon exit from the supply line 122 to a dimension equal to the length of the gap 112. The pyramids 128 and the adapter pieces 126 together constitute the dispensing device, which leads from the feed lines 122 to the outflow nozzle 110.

The longitudinal walls 134 (see Fig. 3) of the convergent portion of the outflow nozzle 110 and of the six pyramids 128 form a truncated V 111 whose angle or angle of convergence (a) is 9 ", this angle of convergence (a) being determined in transverse gap 112. direction. Each longitudinal wall 134 of the outflow nozzle forms a single piece with corresponding walls of the six pyramids, which are cut substantially in the form of truncated equilateral triangles to form the six pyramids.

508 197

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

The feeder device makes it possible to change from multiple feeder lines 122 with a circular cross section to a single rectangular cross section as shown by the slot 112.

This device has considerable advantages because it allows to obtain a homogeneous distribution of steam without introducing any unnecessary pressure loss or stagnation areas where corrosion of the materials in the device would occur.

The height of the V 111 which provides the connection between the six pyramids and the gap 112 (of the order of 20 cm) is chosen so as to obtain a good compromise between the production of uniformity in the flow and the size of the device. The height of the spreading devices, for example on the pyramids 128 is 60 cm.

The gas supply through each supply line 122 can be individually regulated by valves 123, which prove useful for controlling the transverse uniformity in thickness for deposition. In this way, it is possible to take into account and compensate for the occurrence of transverse temperature gradients between the center and the edges of the glass band.

Maintaining a uniform flow rate of steam or gas across the width of the substrate is also facilitated by the parallelism of the walls 124 in the entry slots 112. This parallelism is maintained due to the presence of strands 125 with a profile in the form of a water drop, positioned with its widest portion upstream of the gas stream. The choice of this geometry reduces or eliminates the formation of a tail with different pressure downstream of the end. A strike height of 29 mm and a maximum width of 12 mm have been found suitable. It is preferred that the grooves 125 are positioned sufficiently away from the exit of the groove to avoid formation of streaks in the coating. Preferred is that this distance is

508 197 at least 7 cm. On the other hand, the strings 125 should not be placed too far from the exit of the gap, otherwise they may not provide sufficient stiffness to maintain a constant distance along the length of the gap. Preferably, this distance is less than 15 cm, preferably between 8 and 12 cm, such as 10 cm. Furthermore, a distance between the strands of about 25 cm (exaggerated in the figures for clarity) was used.

The insertion of the reagent into its carrier gas takes place at a tubular conduit 122 at a site prior to its connection to the connector 126. This conduit is equipped with venturi device 127a, 127b. At the neck of the first venturi device 127a, tin chloride SnCl is atomized₄, for example, and this is carried in the hot nitrogen and the carrier gas / vapor mixture is supplemented by passing through a second venturi device 127b. The same applies to the introduction of water vapor into another pipe.

When the installation is used to deposit a coating on a glass strip when it has subsequently left the float water, the entire machine may be placed on a chassis which includes heating elements for the carrier gases and the conduit to connect the hot gases to the terminals 126 which supply the slots 112.

If it is desired to reduce the vertical dimensions of the installation, the vertical pyramid system is replaced by pyramids 128 inclined to the substrate plane in the same plane as the slots 12a, b in Fig. 1.

The variation shown in Figure 9 can be used in the installation of Figure 1 or Figure 3. In this variation, the nozzle 410 has an upper converging head portion 460 which has an axial plane extending substantially perpendicular to the substrate surface to be coated. and a smaller lower convergent portion 462, the axial plane of which is inclined toward the coating surface, and the walls 464 of the lower convergent portion are integral with and continuous with the parallel walls 424 of the gap 412. Strands 425 are provided therein

508 197 the lower convergent portion 462 of the nozzle 410 to maintain the parallel disposition of the walls 424 across the width of the device.

The variation shown in Fig. 10 can be adapted to the installation of Fig. 1 or Fig. 3. In this variation, an outflow nozzle 510 has a slot 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 limiting an upper spring portion 566 and a lower spring portion 567. In the upper spring portion 566, the walls 524 are more apart than in the lower spring portion 567. Strings 525 are provided in the upper groove portion 566 of the groove 512 to maintain the parallelism of the walls 524 across the width of the device.

Example - Asymmetric

The following examples illustrate the use of an asymmetric installation as described in connection with Figures 1, 1A, 2 and 3.

The installation makes it possible to, for example, coatings of tin oxide SnO₂, tin oxide SnO₂ doped with fluorine, titanium dioxide TiO₂, titanium nitride TiN, silicon nitride Si₃N₄ and generally expressed oxides, sulfides, nitrides or carbides.

To form tin oxide coatings SnO₂ or titanium dioxide TiO₂ two successive slots 112 are used. The reagent containing the metal (Sn or Ti) (fed at the first slit 112a) is a tetrachloride, liquid at ambient temperature, evaporated in a stream of anhydrous carrier nitrogen at about 600 ° C. Evaporation is facilitated by the atomization of these reagents in the carrier gas.

To prepare the oxide, the tetrachloride molecules are introduced into the presence of water vapor led to the second slot 112b. The water vapor is superheated to about 600 ° C and is also injected into the carrier gas, which is heated to about 600 ° C. Twist₂

508 197 can be formed, for example, using the proportions of SnCl₄ and H₂0 which is disclosed in British Patent Specification GB 2,026,454 (Glaverbel).

When it comes to the formation of conductive tin oxide SnO₂ is the dopant fluorine: HF is added to the water vapor. The partial pressure for HF is pHF = 0.2 pSnCl₄. Another dopant may also be introduced: liquid antimony chloride SbCl₅, which is directly mixed with tin chloride in SnCl₄ with which it is miscible in any proportion. The presence of the antimony chloride SbCl₅ makes it possible to dye tin oxide SnO₂coating, which can then absorb (and reflect) some of the near-infrared red radiation.

The gas flow rate (carrier gas + reagent) in each slot 112 is 1 m³/ cm per run / h at operating temperature.

To deposit the tin oxide SnO coating₂ or titanium dioxide TiO₂ the Inconel 600 or optionally an even more heat-resistant alloy (Hastelloy) is selected for the parts of the device that are in contact with tin chloride SnCl₄ or titanium chloride TiCl₄ and Monel 400 for the water vapor and the HF gap.

The layer formed is uniform both when examining it macroscopically over the entire width of the coated substrate and when small adjacent zones are examined. The coating is free of strokes.

The symmetrical installation shown in Figs. 4, 5 and 6 comprises a central reagent effluent 212 where on both sides thereof a coating chamber 214a, 214b is comprised of a channel connected to an extractor 218a, 218b. This symmetrical installation essentially occupies the entire width of the glass 16.

Several features of the device are similar to those described with reference to the asymmetrical installation shown in Figures 1, 1A, 2 and 3: injection of reagent into the carrier gas by means of venturi tubes and maintaining the parallelism in

508 197 outflow and extraction slots by water droplet springs 225.

The symmetrical installation shown in Fig. 4, is 3 m long and is designed to have a deflection not exceeding 1 mm even in a high temperature environment.

The installation is suitable for depositing a coating from reagents which must be kept cold until they come into contact with the hot glass 16. The device comprises only a single-discharge effluent 212. Through this gap 212 it is possible to introduce a mixture of several reagents which will react with each other only when the temperature is sufficiently high and therefore on the glass 16. The installation is constructed of aluminum and provided with cooling lines 242.

This mounting is placed at a height 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 small extent or not at all since the coating chamber 214a, b consists of a polished aluminum vault with a very low emissivity, which fulfills the role of a heat mirror.

The installation is airtight due to the presence of gas joints 244 upstream and downstream which prevent any switching between ambient atmosphere and coating chamber 214a, b. Side screens are also provided, extended with suction and a gas joint, especially when it is not possible to use self-lubricating mechanical joints (graphite, boron carbide) (in the case of oxidized layers).

In order to enable the deposition of a layer on a glass substrate in a float water, it is ideally necessary to include apparatus for ensuring accurate geometry and function even at the high temperatures prevailing in a float water. Thus, as shown in Fig. 4, the coating deposition device is attached to a bogie 247 which supports rollers adapted to engage in fixed guide beams. In particular, bogie 247 runs by four

508 197 rolls on two guide beams 249, 251 (IPN 350). The bogie 247 is guided by a pair of rollers 248 with a U-shaped profile running on a first guide beam or rail 249, while lateral movements can be enabled by a pair of cylindrical rollers 250 running on a second guide beam 251 to compensate each transverse beam. variations in the running tracks. These beams are coated with complementary flat iron which has a dual purpose: to increase the moment of inertia, both vertically and horizontally, and also constitute channels in which water circulation can be arranged, which makes it possible to maintain an identical geometry of the device both at ambient temperature and at high temperatures. temperature.

The inlet 212 of the nozzle 210 is provided with five adjustable feeds 246 which lead the steam into an input nozzle in the form of a V-211, which terminates in the gap 212 where the angle of the V or the angle of convergence (a) is 9 *. Alternatively, a greater number of adjustable feeds such as 16 may be present. The height of the nozzle 210 is 20 cm.

The slot 312 may be curved as shown in Figures 7 and 8. While this construction may complicate the installation, it may offer the advantage of a smaller space requirement with respect to height if the walls 324 of the slot 312 are located horizontally and its feeder V is vertical. .

Example - symmetrical

The following examples illustrate the use of a symmetrical installation as described in connection with Fig. 4.

The installation enables the deposition of silica SiO coatings₂ or SiO_x of silane SiH₄ and oxygen in accordance with the disclosures in British Patent Specifications GB 2 234 264 and GB 2 247 691 mentioned above.

A similar installation can also be used to form an alumina coating, A1₂C&gt; 3 of aluminum acetyl 508 197 acetone vapor. In this case, the material is in contact with the reagent vapor stainless steel.

The same type of installation can also be used to deposit a metal coating from a metal carbonyl.

Such an installation can be converted to use reagents which cannot come into contact with each other during their transport to the glass 16. In this case, two feeder Vs are placed side by side, each ending in a inclined gap, whose inclination plane converges towards the second plane's slope plane. This device should ideally not be cooled.

As an example, several successive installations may be used to deposit coatings on glass while the latter is in the float water; especially silica Sio₂ and then vanadium pentoxide V₂O₅ or tungsten oxide WO₃or molybdenum oxide Mo0₃, where sodium in the atomic state will diffuse, to convert this oxide to vanadium, tungsten or molybdenum bronze and finally a tin oxide SnO₂barrier to be laid on top. Tin oxide Sn0₂The barrier can optionally also be deposited on the tape just after it exits from a float water. Such deposits have an electrical conductivity (bronze) so that they are halfway between precious metal and heavily doped semiconductors. Thus, a glass is obtained which carries a coating which is optically very selective with a metallic appearance in reflection and a very low solar factor.

The layer formed is uniform both when examined in a macroscopic manner over the entire width of the coated substrate and when small adjacent zones are examined. The coating is free of strokes.

508 197