Device for preparing a gaseous premix, flame treatment unit and method using said device

Abstract

The present invention relates to a device (1) for preparing a gaseous premix (15) comprising oxygen and at least one organometallic precursor, in gaseous form. The invention also relates to a flame treatment unit (100) comprising such a device (1) and to a surface treatment method using such a device (1) and / or such a flame treatment unit (100).

Description

[0001] DESCRIPTION

[0002] TITLE: Device for preparing a gaseous premixture, flaming unit and method using this device

[0003] The present invention relates to a device for preparing a gaseous premixture comprising oxygen and at least one organometallic precursor, in gaseous form, usable in a flaming unit. The invention also relates to a flaming unit comprising such a device and to a method for treating the surface of a first layer of a support, comprising a flaming step carried out by means of such a device or such a flaming unit, with a view to depositing on said surface a second layer comprising at least one silicon compound and / or at least one titanium compound.

[0004] In the field of surface treatment of supports, several methods are available to those skilled in the art. Depending on the application envisaged for the treated support on the one hand, and the material constituting the support on the other hand, one or more specific methods may be preferred, because they are more particularly suited either to the material of the support or to the desired application.

[0005] For example, a well-known application for which one wishes to treat the surface of a support is the creation of a surface having adhesion properties and corrosion resistance properties. The adhesion properties make it possible to promote adhesion between the material of the support and a coating that one wishes to apply to the support, such as for example an industrial paint or an adhesive, in the automotive, aeronautical or even construction industries. The corrosion resistance properties make it possible to protect in particular supports made of ferrous and non-ferrous metal materials against corrosion. For such an application, to date, when the support is made of aluminum, anodizing is used in a well-known way. When the support is made of steel, cataphoresis is used instead.When the support is a metal alloy, chemical conversion processes will be conventionally used, generally based on Chrome VI, Chrome III or Zinc. When the support is plastic, a standard flame process will be used.

[0006] Another application for which one may want to treat the surface of a support is the creation of an anti-drip and anti-limescale surface. To achieve this, it is necessary to make the treated surface as hydrophilic as possible. This application is generally desired when the support is made of glass, for example for interior glazing, such as shower screens or mirrors, in order to preserve these supports' transparency properties as well as a clean appearance. Another application that may require treating the surface of a support is the creation of a surface with self-cleaning properties. To achieve this, the surface must be treated to make it capable of photocatalytic activity. Photocatalytic activity allows chemical reactions to be carried out in the presence of UV radiation.These chemical reactions allow the formation of free radicals that will react with compounds present on the surface, such as organic dirt, in order to degrade these compounds. Rinsing the support by means of rain or a water spray then makes it possible to eliminate this degraded organic dirt. Such an application is desired for rigid exterior supports, such as bay windows or solar glass, in order to keep the surfaces of these supports clean without having to apply an effective and regular cleaning treatment to these supports.

[0007] For all the applications mentioned above, surface treatments such as plasma-enhanced chemical vapor deposition, also known as PECVD (Plasma Enhanced Chemical Vapor Deposition) or cold plasma can also be used. Plasma is a gas in which a significant percentage of atoms or molecules are ionized. PECVD is performed under vacuum, i.e. at a pressure generally between 1 and 10 -4 and 1 10 -6 bar, while Cold Plasma is carried out inside a torch at atmospheric pressure. In both techniques, all surfaces exposed to the plasma receive a bombardment of high-energy ions. These two techniques thus make it possible to deposit different thin layers created from organometallic chemical precursors on the surface of the support to be treated.

[0008] It appears from the above paragraphs that there are a multitude of processes for treating support surfaces, these processes implementing different technologies and technical means depending on the desired application and the material constituting the support to be treated. In particular, it appears that each application and / or each material involves a different preferred process and that a process recommended for a particular application or for a specific material is difficult to transpose to another application and / or to another material.

[0009] Furthermore, some of these processes, such as anodizing or chemical conversions, require the use of chemical compounds such as Chromium VI, which are recognized as potentially harmful to humans and whose use is not recommended according to the European REACH regulation (Regulation (EC) No. 1907 / 2006 on the Registration, Evaluation, Authorization and Restriction of Chemicals). It would therefore be desirable to have a surface treatment process for supports that would eliminate the use of such compounds. Some of these processes have technical or cost limitations in their implementation. This is the case, for example, when large supports (for example, beyond 2 m 2) must be treated. Thus, Cold Plasma does not generate enough energy to carry out the chemical transformations necessary for the deposition of certain chemical precursors. On the other hand, Cold Plasma generally uses nozzles with diameters ranging from 5 mm to 5 cm for the largest, which implies a very small treatment surface diameter, thus making the treatment of a large surface almost impossible because it is much too long and too expensive.

[0010] Similarly, in the PECVD technique, the support to be treated must be treated in one go. The size of the support will thus determine the dimensions of the machine. The longer the support, the more complex and expensive the machine implementing the PECVD treatment must be. In some cases, depending on the desired deposit, a high-temperature annealing (e.g. 600°C) for several hours (e.g. 5 hours) will be necessary to obtain the appropriate structure of the molecules created, for example an anatase and / or rutile structure of TiO2 when the objective is to give the treated surface photocatalytic properties. Thus, the PECVD process is difficult to adapt to the treatment of large supports. This process can also be very expensive depending on the intended application.

[0011] Some of these processes are not fully effective for the desired applications. For example, it would be interesting to have a process to improve the adhesion properties and corrosion resistance properties of ferrous and non-ferrous materials.

[0012] Furthermore, it is known to cover the surface of a support with a layer comprising a silica compound and / or a titanium compound, in order to give said surface hydrophilic and self-cleaning properties. The layer comprising a silica compound and / or a titanium compound is generally deposited on the surface to be treated by means of a flaming process. Such a process consists of exposing the surface to be treated to an oxidizing flame which is the result of mixing a combustible gas, air and a premixture comprising i) a carrier gas, which may be air, nitrogen or oxygen, and ii) a precursor of silicon oxide and / or a precursor of titanium oxide, in gaseous form.

[0013] In known thin film deposition processes, such as for example in flaming processes, to produce the premixture of carrier gas and precursors of silicon oxide and / or titanium oxide, in gaseous form, an evaporator system is conventionally used comprising a temperature-controlled bath of precursors of silicon oxide and / or titanium oxide, in liquid form, into which the carrier gas is injected. The carrier gas is bubbled within this bath and the gaseous premixture of the carrier gas and precursors of silicon oxide and / or titanium oxide, in gaseous form, is recovered at the outlet.The combustion of this premixture in the flame will create SiO2 molecules and / or TiC>2 molecules, which will be deposited on the surface of the support subjected to the flame, thus giving this surface a layer with particular properties, such as, for example, adhesion and corrosion resistance properties in the case where only SiC>2 has been deposited, or hydrophilic or self-cleaning properties in the case where a combination of SiO2 and TiC>2 has been deposited.

[0014] As appears from the description of the evaporator system described above, in these known thin film deposition processes, the flow rate of the precursors of silicon oxide and / or titanium oxide, in gaseous form, is identical to the flow rate of the carrier gas and there is therefore no way to vary the flow rate of the precursors of silicon oxide and / or titanium oxide in gaseous form, relative to the flow rate of the carrier gas. There is thus no possibility in these known thin film deposition processes to vary the possible reaction between the carrier gas and the precursors of silicon oxide and / or titanium oxide, in gaseous form. It is thus difficult in these known thin film deposition processes to control the thickness of the layer formed on the surface to be treated, the thickness of this layer depending directly on the quantity of molecules deposited, the latter depending on the flow rate of the carrier gas, which is fixed.Thus, the adhesion, corrosion resistance, hydrophilicity or self-cleaning properties conferred on the surface by known thin-film deposition processes are not optimized.

[0015] There therefore remains a need for a device that would make it possible to control the thickness and structure of the layer formed on the surface to be treated. There also remains a need for a method for treating the surface of a support, which would comprise a step of depositing by flame treatment on said surface at least one silicon compound and / or at least one titanium compound, which would be capable of being used for any application and whatever the material constituting the support, which would be easy to implement and inexpensive, and which would make it possible to give said surface optimized properties, for example optimized adhesion, corrosion resistance, hydrophilicity or self-cleaning properties.

[0016] The present invention aims to address this need.

[0017] The Applicant has developed a device for varying the flow rate of organometallic precursors in gaseous form, relative to the flow rate of the carrier gas in the preparation of a premixture usable in a flaming process. The Applicant has also developed a flaming process using such a device and making it possible to deposit on the surface to be treated a layer comprising at least one silica compound and / or at least one titanium compound, while controlling the thickness of the deposited layer as well as the structure of the silica compound and / or the titanium compound, regardless of the material constituting the support. A first subject of the invention relates to a device for preparing a gaseous premixture comprising oxygen and at least one organometallic precursor, in gaseous form, said device comprising: at least one reservoir of said organometallic precursor in liquid form,said reservoir being capable of delivering a flow rate DP of said organometallic precursor, at least one supply of gaseous oxygen, at least one mixer capable of receiving a flow rate DP of said organometallic precursor in liquid form and a flow rate DO of said gaseous oxygen, and of mixing said organometallic precursor and oxygen to obtain a mixture of said organometallic precursor and oxygen, at the temperature of said organometallic precursor in the liquid state, having a flow rate DM, at least one heating system capable of receiving said mixture of said organometallic precursor and oxygen, at the temperature of said organometallic precursor in the liquid state, and of heating said mixture to a temperature greater than or equal to the temperature of the initial boiling point of said organometallic precursor, in order to obtain a gaseous premixture comprising oxygen and the organometallic precursor, in gaseous form, having a flow rate DM.,

[0018] A second object of the invention relates to a flaming unit comprising at least one air supply, at least one fuel gas supply and at least one flame application head, characterized in that it further comprises at least one device as described above.

[0019] A third subject of the invention relates to a method for treating the surface of a first layer of a support, comprising a step of deposition by flame treatment on said surface of a second layer comprising at least one silicon compound and / or at least one titanium compound, said method being characterized in that it is carried out by means of a device as described above and / or by means of a flame treatment unit as described above.

[0020] A fourth subject of the invention relates to a support comprising a first layer on the surface of which has been deposited a second layer comprising at least one silicon compound and / or at least one titanium compound, capable of being obtained according to the above method.

[0021] For the purposes of the present invention, the term “organometallic precursor” means any compound or mixture of compounds capable of producing silicon oxides and / or titanium oxides under the action of an oxidizing flame. Among the organometallic precursors capable of producing silicon oxides under the action of an oxidizing flame and suitable for the present invention, mention may be made of hydrocarbon silanes, fluorosilanes, silicates, organosilicates, siloxane monomers, silazane monomers, and mixtures thereof. Among the hydrocarbon silanes, mention may be made of tetramethylsilane (TMS). Among the fluorosilanes, mention may be made of triethoxyfluorosilane (TEOF). Among the silicates, mention may be made of SiCk. Examples of organosilicates include tetraethoxysilane (TEOS), tetramethoxysilane (TMOS) and their mixtures.Examples of siloxane monomers include hexamethyldisiloxane (HMDSO), tetramethyldisiloxane (TMDS), octamethylcyclotetrasiloxane (OMCTS), and mixtures thereof. Examples of silazane monomers include hexamethyldisilazane (HMDS). Examples of organometallic precursors capable of producing titanium oxides under the action of an oxidizing flame and suitable for the present invention include fluorotitanes, such as titanium tetrafluoride (TiF4), chlorotitanes, such as titanium tetrachloride (TiCk) or titanium trichloride (TiCh), titanium sulfate (Ti(SO4)2), titanium alkoxides, and mixtures thereof. Titanium alkoxides include titanate ethoxide (Ti4(OCH2CH)ie), titanium butoxide (Ti(OBu)4) with Bu = CH2CH2CH2CH3, tetraethyl orthotitanate (TEOT), titanium tetraisopropoxide (TTIP) and mixtures thereof.

[0022] For the purposes of the present invention, the term "initial boiling point" of an organometallic precursor means the temperature at which the organometallic precursor changes from the liquid state to the gaseous state.

[0023] For the purposes of the present invention, the term “silicon compound” means any compound obtained by oxidation by oxidizing flame of an organometallic precursor comprising silicon: for example, the silica compound may correspond to the formula SiOx, with x ranging from 2 to 4.

[0024] For the purposes of the present invention, the term "titanium compound" means any compound obtained by oxidation by oxidizing flame of an organometallic precursor comprising titanium: for example, the titanium compound may correspond to the formula TiOy, with y ranging from 2 to 4.

[0025] In one embodiment, the organometallic precursor is HMDSO. HMDSO makes it possible to deposit silicon oxides (SiOx, as defined above) making the treated surface superhydrophilic (drop angle close to 0 degrees), and therefore very adherent to any successive layers deposited. The silicon oxides also act as an oxygen barrier layer and thus protect the materials from the onset of corrosion.

[0026] In another embodiment, the organometallic precursor is a mixture of hexamethyldisiloxane (HMDSO) and titanium tetraisopropoxide (TTIP). The mixture of HMDSO and TTIP makes it possible to deposit silicon oxides and titanium oxides, mainly crystalline TiO2 in anatase / rutile form, preferably anatase, to obtain a layer having photocatalytic properties. In one embodiment, the reservoir of organometallic precursor in liquid form comprises a system for controlling and / or varying the DP flow rate. Such a system may be programmable. As will appear from the following description, such a system allows the regulation of the DP flow rate relative to the DO flow rate of the oxygen. In particular, such a system makes it possible to act on the DP flow rate without acting on the DO flow rate of oxygen. The system for controlling and / or varying the DP flow rate may comprise an integrated pump.Thus, the reservoir of organometallic precursor in liquid form can, for example, be a syringe pump. Alternatively, the reservoir of organometallic precursor in liquid form can be in the form of a sealed pot in which the organometallic precursor is kept under nitrogen pressure, to which a microdosing pump is connected. In such an embodiment, the microdosing pump makes it possible to control and / or vary the DP flow rate. The use of a microdosing pump makes it possible to limit syringe changes that could potentially cause device shutdowns. The microdosing pump also makes it possible to carry out fillings in masked time.

[0027] In one embodiment, the DP flow rate can range from 1 to 100 g / hour. Such a flow rate makes it possible to inject small quantities of organometallic precursor very precisely. As will be apparent from the detailed description below, this makes it possible to control the thickness and structure of the flame-deposited layer.

[0028] In one embodiment, the device further comprises a system for controlling and / or varying the oxygen flow rate DO. For example, the oxygen flow rate DO may range from 0.3 to 10 L / min. The ability to vary the oxygen flow rate DO independently of the organometallic precursor flow rate DP makes it possible to control the reaction between the organometallic precursor and oxygen within the heating system. Controlling this reaction makes it possible to control the thickness, structure and crystallinity rate of the flame-deposited layer.

[0029] In one embodiment, the heating system is configured to transport said gaseous premixture to an application head of a flaming unit. For example, the heating system comprises a pipe provided with a heating system. For example, one end of said pipe is connected to an outlet of said mixer, the other end of said pipe being capable of being connected to an application head of a flaming unit. The length of the pipe may vary depending on the result that is desired for the layer deposited by flaming, which may depend on the duration of the reaction between the oxygen and the organometallic precursor within the pipe. Indeed, the organometallic precursor passes from the liquid phase to the gaseous phase within the heating system, for example within the pipe. The reaction between the gaseous oxygen and the organic precursor in gaseous form therefore takes place within this heating system, for example within the pipe.Oxygen helps increase the inorganic structure of the flame-deposited layer. Increasing this inorganic structure helps limit the appearance of defects linked to the presence of carbon.

[0030] Thanks to the device according to the invention, it is therefore possible to vary the flow rate of oxygen DO within the gaseous premix present in the heating system, and therefore to control the inorganic structure of the deposited layer, in other words to increase or on the contrary reduce this inorganic structure, and thus to influence the quality of this layer with respect to the properties that one wishes to confer on this layer.

[0031] In particular, depending on the oxygen flow rate DO that will be chosen, more or less organometallic precursor molecules can be oxidized. It will therefore be possible to vary the number of organometallic precursor molecules that will be oxidized by oxygen. It will therefore be possible to control the ratio between the inorganic bonds created (for example the SiOx or TiOy bonds as defined above) and the organic bonds created (in other words the SiCHxi and TiCHyi bonds where xi goes from 1 to 3, and yi goes from 1 to 3). In particular, it will be possible to increase the number of inorganic bonds, which will have the consequence of limiting the number of organic bonds, and therefore of limiting the presence of carbon. The quality of the second layer is thus improved with respect to the properties that one wishes to confer on the treated support, such as for example adhesion, anti-corrosion, photocatalytic properties.

[0032] The device according to the invention is intended to be used with an energy supply system, such as for example a flaming unit or an atmospheric plasma generator. In particular, the device according to the invention is intended to be used within a flaming unit in order to deposit a layer comprising at least one silicon compound and / or at least one titanium compound, on a surface to be treated.

[0033] Thus, the invention also relates to a flaming unit comprising at least one air supply, at least one fuel gas supply, at least one flame application head, and a device as described above.

[0034] Preferably, the heating system of the device is connected to the flame application head. For example, an outlet of the heating system joins the air and fuel gas supply at the flame application head. In operation of the flaming unit, a flame is created by mixing air and fuel gas, for example propane. The flame provides a strong source of energy. For example, the flame can burn at approximately 1800 °C. Thus, the reaction between gaseous oxygen and the organometallic precursor in gaseous form, which was initiated within this heating system, continues at the flame application head. Thanks to the heat input from the flame, oxides of the organometallic precursor are created and graft onto the surface of the first layer of the support to be treated, thus forming a second layer, deposited by flame application.In one embodiment, the flame application head and the heating system are mounted on a mobile robot arm. Such an embodiment of the flaming unit allows all types of media to be processed, regardless of their dimensions and complexity. For example, media with concave and / or convex shapes can be processed easily.

[0035] The device according to the invention and / or the flaming unit according to the invention are intended to be used for implementing a method according to the invention relating to the treatment of the surface of a first layer of a support, aiming to deposit by flaming a second layer on the surface of this first layer, the second layer comprising at least one silicon compound and / or at least one titanium compound.

[0036] Preferably, the method according to the invention comprises the following steps:

[0037] A) a gaseous premixture comprising oxygen and at least one organometallic precursor, in gaseous form, is prepared using a device as described above,

[0038] B) exposing said surface to an oxidizing flame which is the result of mixing a combustible gas, air and said gaseous premixture in order to deposit said second layer on the surface of the first layer.

[0039] During the actual flaming step, in other words when the surface is exposed to the oxidizing flame, the reaction between oxygen and the organometallic precursor in gaseous form, initiated within the heating system of the device according to the invention, continues. Under the effect of the heat of the oxidizing flame, oxides of the organometallic precursor are created and grafted directly onto the surface exposed to the flame.

[0040] A second layer is thus obtained, this second layer comprising oxides of the metal precursor, for example silica compounds such as silicon oxides and / or titanium compounds such as titanium oxides.

[0041] In the method according to the invention, the deposition of the second layer on the surface of the first layer can be carried out in several flame passes over the surface of the first layer.

[0042] The second layer can have a thickness ranging, for example, from 100 nm to 800 nm.

[0043] The combustible gas can be, for example, propane. Alternatively, the combustible gas can be butane. It is also possible to use natural gas distributed to the user in urban networks, such as city gas, as a combustible gas in places where such networks exist.

[0044] In one embodiment, the method according to the invention comprises the following step C): C) the flow rate DO of the gaseous oxygen is varied relative to the flow rate DP of said organometallic precursor, in said gaseous premixture, in order to control the oxidation reaction between the oxygen and said organometallic precursor in gaseous form, and thus control the thickness and / or the inorganic structure of the second layer.

[0045] The method according to the invention has multiple advantages.

[0046] The method according to the invention makes it possible to treat supports whose first layer can be of any nature. For example, this first layer can be made of glass, plastic, ferrous and non-ferrous metals, such as stainless steel, aluminum, steel, magnesium, etc. The device according to the invention, the flaming unit according to the invention and the method according to the invention make it possible to combine in a single system the possibility of replacing different surface treatments. As seen above, in general, in the prior art, a type of support is associated with a surface treatment. For example, to treat steels, it is generally necessary to install cataphoresis; for aluminums, anodization is used, for plastics, standard flaming will be used.The device and method according to the invention make it possible to implement a set of different surface treatments aimed at creating adhesion between the layers and providing resistance to corrosion. The method according to the invention thus constitutes a multi-support surface treatment making it possible to limit the complexity of installation, use, and maintenance of each of the methods and thus to reduce the overall cost. This allows, where appropriate, a standardization of the method to thus limit the individual complexities of installation, use, monitoring, and maintenance.

[0047] The process according to the invention does not require an annealing step. Indeed, in the process according to the invention, the heat input from the flame occurs simultaneously with the reaction between oxygen and the organometallic precursor. Furthermore, with the process according to the invention, the consumption of organometallic precursors is between 1 g / h and 100 g / h, which is very low compared to conventional chemical conversion processes which use hundreds or even thousands of liters of chemicals and water, the proportions of which must be checked and adjusted daily. The process according to the invention is carried out using a dry process, unlike the majority of known surface treatments, many of which are carried out using a wet process and are therefore, by definition, very water and energy intensive.In these prior art processes, the baths are generally maintained at the correct temperature and in the correct proportions daily, even when the treatment line is not in use. Their operation requires continuous use. The process according to the invention does not require continuous use; it can be implemented only when needed, on an ad hoc basis, with the possibility of being stopped and then restarted. Thus, in the process according to the invention, the consumption of chemicals, energy and water is much lower than that of the prior art processes. Furthermore, in the process according to the invention, the handling of potentially dangerous chemicals is very limited, due to the low consumption of organometallic precursors. The process according to the invention makes it possible to avoid the use of Chromium VI or Chromium III.The process according to the invention therefore constitutes an economical and ecological process compared to prior art processes such as PECVD processes.

[0048] Furthermore, in the method according to the invention, the flame application head can be adapted according to the surfaces to be treated. The cycle time is thus adaptable. Generally, this cycle time will be much shorter than in the chemical grafting methods of the prior art. For example, when the device according to the invention is mounted on a robot arm, the step of applying the second layer by flame application can be put in line with a production line. The cycle time is driven by the speed of the robot and the number of passes and layers to be deposited. It is thus possible to reduce the processing time by multiplying the application heads of the flame application unit. In such a case, the application speeds per layer can be around 200 mm / s.

[0049] The device and method according to the invention also allow a significant ergonomic gain. When the device according to the invention is mounted on an application robot, a cell of a dozen m 2 is sufficient to accommodate all the infrastructure needed to implement the surface treatment. This is generally not the case in prior art processes. Anodizing requires a succession of chemical baths occupying at least hundreds of m 2 The space required to implement PECVD depends on the size of the media to be treated but it can very quickly represent a significant volume in a workshop.

[0050] The method according to the invention thus constitutes a multi-support surface treatment, particularly simple to implement and effective.

[0051] The fields of application of the method according to the invention are also multiple.

[0052] When the second layer deposited by the process according to the invention essentially comprises siliceous compounds, this second layer has the following properties:

[0053] Adhesion and anti-corrosion properties: the applications of the process according to the invention can thus concern industry in general such as the automotive or aeronautical sectors. The painting and bonding lines can be preceded by a surface treatment according to the process according to the invention, which then plays the role of pre-treatment by providing the adhesion and corrosion resistance properties according to the respective specifications of the users;

[0054] Anti-drip, anti-limescale and anti-fog properties: the applications of the process according to the invention can thus concern all types of interior glazing such as shower screens to keep them clean and mirrors to make them anti-fog.

[0055] When the second layer deposited by the process according to the invention comprises a mixture of siliceous compounds and titanium compounds, this second layer has photocatalytic, and therefore self-cleaning, properties. The applications of the process according to the invention can thus concern all types of rigid exterior surfaces in order to keep them clean over time and to make them depolluting (destruction of surrounding organic matter by photocatalysis), for example the exterior glazing of individual houses, buildings, photovoltaic panels in order to prevent their fouling which can cause them to lose up to 40% of their efficiency, tiles to prevent the appearance of moss and avoid having to treat a roof annually.

[0056] The present invention and its advantages will emerge from the detailed description which follows and from the figures in which:

[0057] [Fig. 1] is a diagram showing a first embodiment of the device according to the invention and of the flaming unit according to the invention,

[0058] [Fig. 2] is a diagram showing a second embodiment of the device according to the invention and of the flaming unit according to the invention.

[0059] Referring to Figure 1, a device 1 for preparing a pre-gas mixture according to the invention is shown, as well as a flaming unit 100 according to the invention, comprising the device 1.

[0060] The device 1 comprises a syringe pump 2 comprising a syringe 3 filled with an organometallic precursor in liquid form 4. The syringe pump 2 is configured to deliver a flow rate DP of the organometallic precursor to the outlet 3a of the syringe 3. Preferably, the flow rate DP ranges from 1 to 100 g / hour. The syringe pump 2 allows the user to vary the flow rate DP on demand. In the example shown, the syringe pump 2 is located within a plate 5 whose temperature is regulated, for example using a temperature regulation box (not shown), at a temperature making it possible to maintain the organometallic precursor in its liquid form. For example, the regulation temperature of the plate 5 is approximately 40°C.

[0061] The outlet 3a of the syringe 3 is provided with a conduit 6 capable of transporting the organometallic precursor 4, according to the flow rate DP, to a mixer 7. The device 1 further comprises a gaseous oxygen supply 8 provided with a conduit 9 for bringing the gaseous oxygen to the mixer 7. For example, the gaseous oxygen may initially be under a pressure of 0 to 3.5 bars. The conduit 9 transporting the gaseous oxygen is provided with a flow regulator 10 for delivering the gaseous oxygen with a flow rate DO. The flow rate DO ranges, for example, from 0.3 to 10 L / min.

[0062] The mixer 7 is provided with an inlet 7a and an outlet 7b. The inlet 7a of the mixer 7 receives the organometallic precursor in liquid form 4, at a flow rate DP, from the syringe pump 2, and the gaseous oxygen, at a flow rate DO, from the gaseous oxygen supply 8. The mixer 7 integrates these compounds to produce a mixture 11 of the organometallic precursor in liquid form and the gaseous oxygen, the mixture 11 being at the temperature of the organometallic precursor in liquid form, for example approximately 40°C. The mixture 11 has a flow rate DM.

[0063] The device 1 further comprises a heating system 12 comprising a conduit 13 and a pipe 14 forming a sheath for the conduit 13. The conduit 13 is configured to receive and transport the mixture 11 exiting through the outlet 7b of the mixer 7 to the application head 101 of the flaming unit 100. The heating system 12 is provided with a heating system capable of bringing the conduit 13 to the temperature of the initial boiling point of the organometallic precursor. For example, the heating system is in the form of a resistor located between the conduit 13 and the pipe 14, said resistor being connected to an electrical power supply, for example of voltage 230 V, to heat the conduit 13. The resistor may for example be in the form of a bundle of copper wires which surround the conduit 13. Thus, in general, the conduit 13 may have a temperature ranging from 0 to 240°C.The heating system 12 thus makes it possible to heat the mixture 11 to the temperature of the initial boiling point of the organometallic precursor so as to form within the conduit 13 a pre-mixture 15 comprising oxygen and the organometallic precursor, in gaseous form.

[0064] The heating system 12 preferably has a sufficient length to allow and ensure the transformation of the mixture 11 comprising the organometallic precursor in liquid form into the gaseous premixture 15. For example, the heating system may have a length ranging from 1 to several meters. The conduit 13 may for example be made of polytetrafluoroethylene (PTFE), and the pipe 14 may for example be a braided sheath of polyamide forming an insulator and allowing the heating system 12 to be handled without danger of burning the user.

[0065] At the outlet 12b of the heating system 12, the gaseous premix 15 has a flow rate DM.

[0066] Still with reference to Figure 1, the flaming unit is now described.

[0067] 100. The flaming unit 100 comprises the device 1 described above as well as an application head 101 connected to the outlet 12b of the heating system 12. The flaming unit 100 also comprises an air supply 102 and a fuel gas supply 103. The air leaving the air supply 102 may for example be at a pressure ranging from 0 to 7 bar. The fuel gas leaving the fuel gas supply 103 may for example be propane. It may be at a pressure ranging from 0 to 70 mBar. In the example shown, the flaming unit 101 comprises a plate 104 comprising a system for adjusting the flow rate and pressure of the air 105 as well as a system for adjusting the flow rate and pressure of the combustible gas 106. The flaming unit 100 also comprises conduits for supplying the air 107, the combustible gas 108 and the air + combustible gas mixture 109 to the application head 101.

[0068] The air + combustible gas mixture supply duct 109 joins the outlet 12b of the heating system 12 at the level of the application head 101.

[0069] In operation of the flaming unit 100, a flame 110 is produced by the mixture of air and combustible gas at the outlet of the application head 101. The gaseous premixture 15 is injected into the air + combustible gas mixture.

[0070] The board 104 of the flaming unit 100 also comprises an ionization measurement system, which may be in the form of a microammeter 11 1 , for example a microammeter of the trade name Weigel Mepgerate Gmbh Type PQ48K MB / range 0-40pA DC. The ionization measurement makes it possible to verify the correct operation of the flaming unit 100. For example, an ionization value of less than 5 microamps makes it possible to verify the correct operation of the flaming unit 100.

[0071] Thus, when injecting the gaseous premix 15 into the air + fuel gas mixture, the initial value of the ionization of the air + fuel gas mixture alone is lost. Monitoring a change in color of the flame produced as well as a return of the ionization value to a value lower than 5 microamps makes it possible to ensure that the transformation of the organometallic precursor from its liquid phase to its gaseous phase has indeed taken place and that the flaming unit 100 is operating correctly.

[0072] It is then possible to apply the flame 110 to the surface of the first layer of a support in order to deposit on this surface a second layer, which will comprise oxides of the organometallic precursor. The deposition of the second layer can be done in several flame passes on the surface of the first layer.

[0073] Referring to Figure 2, a flaming unit 101 similar to that of Figure 1 is shown, in which the syringe pump has been replaced by a nitrogen pressure pot and a microdosing pump. The same references have been retained for the identical elements of Figure 1 and Figure 2. Referring to Figure 2, the device 1 comprises a sealed pot 16 comprising the organometallic precursor in liquid form 4. The interior of the pot 16 is under nitrogen pressure 17, supplied via a conduit 18 from a nitrogen supply 19. The conduit 18 is provided with a nitrogen pressure regulation system 20.

[0074] A conduit 21 transports the organometallic precursor from the pot 16 to the inlet 7a of the mixer 7. The conduit 21 is equipped with a microdosing pump 22 making it possible to regulate the flow rate DP of the organometallic precursor.

[0075] Examples of implementation of the method according to the invention using the flaming unit 100 as described in Figure 1 are given below.

[0076] Example 1

[0077] Deposition of a layer comprising silicon compounds such as silicon oxides on the surface of a support of which the first layer as defined in the description above is made of aluminum.

[0078] A flaming unit according to Figure 1 is used. The following steps are carried out.

[0079] Ignition of the flaming unit + adjustment of the air and combustible gas flow rates Ignition of the temperature control box of the syringe pump so that the liquid precursor is at a temperature of 40°C

[0080] Preparation of the organometallic precursor: here, the organometallic precursor is HMDSO (Hexamethyldisiloxane)

[0081] Starting the heating of the heating system: in this case, the pipe is heated to 140°C, which represents a temperature higher than the boiling temperature of HMDSO which is 101°C

[0082] Opening the air, fuel gas and oxygen valves. Here, the fuel gas is propane,

[0083] Oxygen flow setting DO to 1 L / min

[0084] Ignition of the flame by adjusting the air / propane mixture to a ratio of 50 / 50 by volume Injection of the organometallic precursor at a DP flow rate of 20 g / h

[0085] Waiting for the correct rise and transformation of the HMDSO from its liquid phase to its gaseous phase, noticeable by the change in color of the flame and the value of the return of the ionization readable on the flaming machine less than 5 microamps. The flame is applied, possibly in several passes, on the surface of the first layer of the support.

[0086] A second layer comprising silicon oxides is then deposited on this surface.

[0087] The choice of the DO flow rate allows to control the reaction of oxygen and HMDSO gas within the heating system and at the outlet of the application head, in order to control the thickness of the deposited layer as well as the inorganic structure of the latter, as explained in the description above.

[0088] The deposited layer has adhesion and anti-corrosion properties as well as anti-drip, anti-limescale and anti-fog properties.

[0089] Example 2

[0090] This example is carried out in the same way as Example 1, except for the oxygen flow rate DO, which this time was set at 2 L / min.

[0091] Thus, the layer deposited in this Example 2 has a different thickness and inorganic structure than the layer deposited in Example 1. In particular, the layer deposited in this Example 2 has a greater thickness and a more inorganic structure than the layer deposited in Example 1.

[0092] The layer deposited in this Example 2 exhibits adhesion and anti-corrosion properties as well as anti-drip, anti-limescale and anti-fog properties.

[0093] Example 3

[0094] Deposition of a layer comprising silicon compounds, such as silicon oxides and titanium compounds, such as titanium oxides, on the surface of a support of which the first layer as defined in the description above is made of glass.

[0095] A flaming unit according to Figure 1 is used. The following steps are carried out.

[0096] Ignition of the flaming unit + adjustment of the air and combustible gas flow rates Ignition of the temperature control box of the syringe pump so that the liquid precursor is at a temperature of 40°C

[0097] Preparation of the organometallic precursor: here, the organometallic precursor is a mixture of HMDSO (Hexamethyldisiloxane) and TTIP (Titanium Isopropoxide) at a volume mixture of 5 / 95 respectively

[0098] Starting the heating system: in this case, the pipe is heated to 240°C, which is a temperature higher than the boiling temperature of the TTIP, which is 232°C

[0099] Opening the air, fuel gas and oxygen valves. Here, the fuel gas is propane,

[0100] Oxygen flow DO setting at 5L / min

[0101] Ignition of the flame by adjusting the air / propane mixture to a ratio of 50 / 50

[0102] Injection of the organometallic precursor at a DP flow rate of 30 g / h

[0103] Waiting for the correct rise and transformation of the mixture of HMDSO and TTIP from its liquid phase to its gaseous phase, noticeable by the change in color of the flame and the value of the return of the ionization readable on the flaming machine less than 5 microamps.

[0104] The flame is applied, possibly in several passes, to the surface of the first layer of the support.

[0105] A second layer comprising silicon oxides and titanium oxides is then deposited on this surface.

[0106] The choice of the DO flow rate allows to control the reaction of oxygen and the mixture of HMDSO and TTIP gas within the heating pipe and at the outlet of the application head, in order to control the thickness of the deposited layer as well as the inorganic structure of the latter, as explained in the description above.

[0107] The deposited layer has photocatalytic properties.

[0108] Example 4

[0109] This example is carried out in an identical manner to Example 3, except for the oxygen flow rate DO, which was set this time at 7 L / min. Thus, the layer deposited in the present Example 4 has a different thickness and inorganic structure from the layer deposited in Example 3. In particular, the layer deposited in the present Example 4 has a greater thickness and a more inorganic structure than the layer deposited in Example 3.

[0110] The layer deposited in this Example 4 exhibits adhesion and anti-corrosion properties as well as photocatalytic properties.

Claims

CLAIMS 1. Device (1) for preparing a gaseous premixture (15) comprising oxygen and at least one organometallic precursor, in gaseous form, said device (1) comprising: at least one reservoir (2; 16) of said organometallic precursor in liquid form (4), said reservoir (2;16) being capable of delivering a flow rate DP of said organometallic precursor, at least one gaseous oxygen supply (8), at least one mixer (7) capable of receiving the flow rate DP of said organometallic precursor in liquid form (4) and a flow rate DO of said gaseous oxygen, and of mixing said organometallic precursor and oxygen to obtain a mixture (11) of said organometallic precursor and oxygen, at the temperature of said organometallic precursor in the liquid state, having a flow rate DM, at least one heating system (12) capable of receiving said mixture (11) of said organometallic precursor and oxygen, at the temperature of said organometallic precursor in the liquid state (4), and of heating said mixture to a temperature greater than or equal to the temperature of the initial boiling point of said organometallic precursor, in order to obtain a gaseous premixture (15) comprising oxygen and the organometallic precursor, in gaseous form, having a flow rate DM.; 2. Device (1) according to claim 1, characterized in that said reservoir (2; 16) of organometallic precursor in liquid form (4) comprises a system making it possible to control and / or vary the DP flow rate (2; 22).

3. Device (1) according to claim 1 or 2, characterized in that the reservoir of organometallic precursor in liquid form (4) is a syringe pump (2).

4. Device (1) according to claim 1 or 2, characterized in that the reservoir of organometallic precursor in liquid form (4) is in the form of a sealed pot (16) in which the organometallic precursor is kept under nitrogen pressure, to which a microdosing pump (22) is connected.

5. Device (1) according to any one of the preceding claims, characterized in that the flow rate DP ranges from 1 to 100 g / hour.

6. Device (1) according to any one of the preceding claims, characterized in that it further comprises a system making it possible to control and / or vary the flow rate of oxygen DO (10).

7. Device (1) according to any one of the preceding claims, characterized in that the flow rate DO ranges from 0.3 to 10 L / min.

8. Device (1) according to any one of the preceding claims, characterized in that the heating system (12) is configured to transport said gaseous premixture (15) to an application head of a flaming unit.

9. Device (1) according to any one of the preceding claims, characterized in that the heating system (12) comprises a pipe (14) provided with a heating system.

10. Device (1) according to claim 9, characterized in that one end of said pipe (14) is connected to an outlet (7b) of said mixer (7), the other end of said pipe (14) being capable of being connected to an application head of a flaming unit.

11. Device (1) according to any one of claims 1 to 10, characterized in that the organometallic precursor is hexamethyldisiloxane (HMDSO).

12. Device (1) according to any one of claims 1 to 10, characterized in that the organometallic precursor is a mixture of hexamethyldisiloxane (HMDSO) and titanium isopropoxide (TTIP).

13. Flaming unit (100) comprising at least one air supply (102), at least one fuel gas supply (103) and at least one flame application head (101), characterized in that it further comprises at least one device (1) according to any one of claims 1 to 12.

14. Flaming unit (100) according to claim 13, characterized in that the heating system (12) is connected to said flame application head (101).

15. Flaming unit (100) according to claim 13 or 14, characterized in that the flame application head (101) and the heating system (12) are mounted on a mobile robot arm.

16. Method for treating the surface of a first layer of a support, comprising a step of depositing by flame on said surface a second layer comprising at least one silicon compound and / or at least one titanium compound, said method being characterized in that it is implemented by means of a device (1) according to any one of claims 1 to 12 and / or by means of a flame unit (100) according to any one of claims 13 to 15.

17. Method according to claim 16, characterized in that it comprises the following steps: A) a gaseous premixture (15) comprising oxygen and at least one organometallic precursor, in gaseous form, is prepared by means of a device (1) according to any one of claims 1 to 12, B) exposing said surface to an oxidizing flame which is the result of mixing a combustible gas, air and said gaseous premixture (15) in order to deposit said second layer on the surface of the first layer.

18. Method according to claim 16 or 17, characterized in that it comprises the following step C): C) the flow rate DO of the gaseous oxygen is varied relative to the flow rate DP of said organometallic precursor, in said gaseous premixture (15), in order to control the oxidation reaction between the oxygen and said organometallic precursor in gaseous form, and thus control the thickness and / or the inorganic structure of the second layer.

19. Method according to any one of claims 16 to 18, characterized in that the combustible gas is propane.

20. Method according to any one of claims 17 to 19, characterized in that during step B), the deposition of the second layer on the surface of the first layer is done in several passes of the flame over the surface of the first layer.

21. Support comprising a first layer on the surface of which has been deposited a second layer comprising at least one silicon compound and / or at least one titanium compound, capable of being obtained according to the method according to any one of claims 16 to 20.

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