WO2013064728A2

WO2013064728A2 - Surface treatment device and method

Info

Publication number: WO2013064728A2
Application number: PCT/FI2012/051037
Authority: WO
Inventors: Simo Tammela; Tuomo MÄÄTTÄ
Original assignee: Beneq Oy
Priority date: 2011-11-01
Filing date: 2012-10-29
Publication date: 2013-05-10
Also published as: WO2013064728A3

Abstract

A surface treatment device for depositing defined particles on a substrate. The device comprises a first mixing space, and a source unit for inputting into the first mixing space atomised droplets of a liquid substance carrying one or more precursors of the defined particles. Liquid substance of the droplets are evaporated within the first mixing space for outputting an aerosol flow carrying precursors of the defined particles from the first mixing space. Spatial uniformity of the resulting surface treatment is significantly improved.

Description

SURFACE TREATMENT DEVICE AND METHOD

FIELD OF THE INVENTION

The present invention relates to a surface treatment device and method according to preambles of the independent claims. BACKGROUND ART

Surface treatment refers here to a layering process where a surface layer of a substrate is modified by allowing particles to diffuse in a surface layer of the substrate matrix, or by depositing particles on the substrate surface such that a layer is produced on the substrate. Particles used for such surface treatments are typically very small, the mean particle diameter ranging from 10 to 100 nm. Particles of this size are typically generated in a particle synthesis process where precursor chemicals are exposed to intensive heat of a thermal reactor. In the heat the precursor chemicals undergo specific thermochemical and -physical reactions that lead to development of desired particles.

In industrial applications, the particle synthesis process typically incorporates a point source that ejects a combination of precursor substances for surface treatment particles, and a thermal reactor that transforms the combination of precursor substances to a progressing particle flow. Typically the thermal reactor is a flame into which the nozzle outlet channels from one or more nozzles feed materials, either mixed together or through separate outlets.

The problem with conventional surface treatment devices is that they do not adapt well to treatment of large surfaces, and especially to treatment of large planar objects. The flow of particles from a point source can cover only a limited area, so in order to treat a planar object, a treatment unit with one point source needs to traverse across a treated area, or a number of point sources need to be connected together to form a treatment unit that wipes over a larger region of the treated area. However, the distribution of substances and flows within a liquid spray flame are not spatially uniform, so the result achieved with either of such treatment units is in most cases not appropriate for the intended purpose. For example, surface treatment of glass surfaces is very vulnerable to spatial irregularities and even very minor spatial uniformity in the deposited or doped layers on the surface of the glass lead to poor end results. SUMMARY

An object of the present invention is thus to provide a surface treatment device and a surface treatment method that provide improved uniformity in the resulting treated surface. The object of the invention is achieved by a surface treatment device and surface treatment method, which are characterized by what is stated in the independent claims. The preferred embodiments of the invention are disclosed in the dependent claims.

The invention is based on introducing to the surface treatment device a first mixing space into which atomised droplets that carry precursors of the desired surface treatment processes are input. In the first mixing space liquid substances carrying the precursors are evaporated, and the resulting substances mix into a uniform composition aerosol in which particles flow from the first mixing space. The resulting aerosol flow may then be exposed to the extreme temperatures applied in flame-based surface treatment processes for particle generation. Due to the improved spatial uniformity of the particles flowing into the flame, the spatial uniformity of the resulting surface treatment is significantly improved.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, embodiments will be described in greater detail with reference to accompanying drawings, in which

Figure 1 an embodiment of a surface treatment device;

Figure 2A illustrates a side view of another embodiment of the surface treatment device;

Figure 2B illustrates a front view of the other embodiment of the surface treatment device;

Figure 2B illustrates a bottom view of the other embodiment of the surface treatment device;

Figure 3 illustrates front and side views of a configuration in an em- bodiment of the invention;

Figure 4 illustrates a side view of an embodiment of a surface treatment device;

Figure 5 illustrates a side view of another embodiment of a surface treatment device;

Figure 6 illustrates stages of an embodiment of a surface treatment method.

DETAILED DESCRIPTION OF SOME EMBODIMENTS The following embodiments are exemplary. Although the specification may refer to "an", "one", or "some" embodiment(s), this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide further embodiments.

In the following, features of the invention will be described with a simple example of a device architecture in which various embodiments of the invention may be implemented. Only elements relevant for illustrating the embodiments are described in detail. Various implementations of surface treatment methods and devices comprise elements that are generally known to a person skilled in the art and may not be specifically described herein.

A surface treatment device refers here to an apparatus that generates particles applicable for a particular type of surface treatment and directs them towards a surface to be treated. According to an embodiment of the invention, the surface treatment is configured to perform a particle synthe- sis process that takes place in a defined temperature range. Typically temperatures for particle generation are achieved in flame-based thermal reactors where particle generation mainly occurs in temperatures above 1700 degrees Celsius. During a particle generation process, the flame, which may be a hydrogen-oxygen flame, is fed with precursor chemicals, and in the intense heat of the flame, the precursor chemicals undergo thermochemical and -physical reactions, ultimately leading to the synthesis of particulate matter on or in the surface to be treated. The particles produced for the surface treatment principally exhibit a size distribution ranging from 10 to 10000 nm, depending on the precursor composition and process parameters.

Figure 1 shows an embodiment of a surface treatment device according the invention. The surface treatment device is suitable for depositing defined particles on a substrate and comprises a source unit 100, a first mixing space 150, and means 170 for providing a thermal reactor.

The source unit 100 is configured to input into the first mixing space 150 atomised droplets of a liquid substance carrying one or more precursors of the defined particles to be used in deposition. In the embodiment of Figure 1 , the source unit 100 comprises reservoirs 102, 104, 106 of various substances necessary for the generation of the particles. In Figure 1 the reservoirs 102, 104, 106 have been illustrated as storage containers, but for a person skilled in the art it is clear that a reservoir may be implemented also in other ways, for example, as a feed connection from a remote material supply system. The reservoirs comprise at least a precursor source 102 that provides one or more precursors of the defined particles in a solution that is in liquid form. Before inputting a precursor substance into the first mixing space 150, the liquid mix- ture from the precursor source is atomized into droplets. A droplet refers here to a very small sized drop, the diameter of a droplet typically being from 100 urn down to sub micron. Accordingly, the source unit comprises also an atomizer 108 that may be implemented, for example, as a two-fluid atomizer where gas is used to break up the liquid feed into droplets. The liquid droplets and the atomizing gas form an aerosol that sprays out of the nozzle 108 and into the first mixing space 150. Other methods of atomization, like a vibrating ultrasound plate, may naturally be applied without deviating from the scope of protection.

The first mixing space 150 is formed by a casing 152 that encloses an impermeable volume in which input substances are confined to mix together. The substances move in the first mixing space along the form of the casing and according to dynamics of flows that stream in and out of the casing. Impermeable in this context means that the first mixing space 150 confined by the casing 152 is detached from ambient environment around the casing 152 such that fluids (gas and/or liquids) do not substantially enter or exit the first mixing space 150 through the casing 152. Heat or electromagnetic radiation may, however, be transferred through the casing 152. Substances exit the impermeable first mixing space through an outlet 154 that outputs an aerosol flow 166 from the first mixing space. The outlet 154 is advantageously opposite to the feeds of reservoirs 102, 104, 106 and may be implemented, for example, as a second nozzle that constricts the cross-sectional area of the first mixing space in the direction of the flow 166.

A thermal reactor 170 represents here means for providing a local distribution of heat such that objects traversing locations of that distribution are exposed to the heat accordingly. The thermal reactor 170 is arranged in proximity to the outlet 154 of the casing 152 and positioned such that the aerosol flow 166 conning out of the first mixing space is exposed to the intensive heat of the thermal reactor 170. In Figure 1 the heat of the thermal reactor 170 is generated by burning combustible substances and comprises two burners 172, 174 installed in the immediate vicinity of the outlet 154 in the casing 152.

The surface treatment device of the embodiment comprises an evaporation mechanism for evaporating liquid substances of the droplets in the first mixing space. One or more liquid substances in the solution coming from the precursor source 102 carry one or more precursors of particles used in deposition. When the liquid substances are evaporated in the first mixing space, the aerosol flow 166 coming out of the outlet is mainly formed of an aerosol of gases and precursors of the defined particles in solid form. In the heat of the thermal reactor, the precursors coming out of the first mixing space may then go through the conventional reaction, condensation, nucleation and coagulation processes for synthesis of particles of flame-based deposition.

In the embodiment of Figure 1 , evaporation in the first mixing space is implemented by controlled preburning where temperature within the preburn- ing space is limited to a range above the evaporation temperature of one, more or advantageously all liquid substances in the mix that is input from the precursor source 102. In order to achieve this, the reservoirs may comprise also a source 104 for burning substances. Burning substances refer here to a mixture of one or more combustible fluids that may be ignited to burn in an exothermic process in the first mixing space 150. Combustible fluids typically comprise combustible gases, like hydrogen, methane, propane or butane.

The reservoirs may comprise further a source 106 for burn control substances. Burn control substances refer here to fluids that effect on a burning process, typically in relation to their relative proportion in the space where burning takes place. Burn control substances often comprise an oxygen carrying gas, for example air, oxygen, or ozone. Burn control substances may also comprise one or more inert gases, like nitrogen or carbon dioxide.

In the present embodiment, the liquid droplets, burning substances and burn control substances from their respective reservoirs 102, 104, 106 are input via their respective feeds into the first mixing space 150 where they are efficiently mixed, evaporated and form a homogeneous combustible aerosol. It is noted that Figure 1 only illustrates functional elements necessary for de- scribing the present embodiment. The functional elements may be implement- ed in various ways. For example, a combustible gas or a burn control gas may be partially fed in as an atomizing gas of the two-fluid atomizer.

The first mixing space 150 comprises a control mechanism 156 for adjusting burning temperature in the first mixing space to the predefined tem- perature range. In the embodiment of Figure 1 the control mechanism is illustrated by means of a controller 156, which is an operational unit that interconnects sensors 158, flow control elements 160, 162, 164 and control logic 168. In the controller these elements are functionally connected such that the one or more sensors 158 monitor burning conditions within the process space 150, the one or more flow control elements 160, 162, 164 control input flows from individual feeds, and the control logic 157 adjusts the input flows in response to input from the sensor signals. Flow control elements 160, 162, 164 may be implemented as control valves or in various other ways, well known to a person skilled in the art. The sensors 158 advantageously comprise a thermosen- sor by means of which the controller 156 may, during operation, monitor the prevailing temperature within the first mixing space 150. Local temperatures within the first mixing space vary, depending on the flow conditions in the applied configuration. For practical implementations, the temperature measured in outer or inner surface of the casing 152 is considered to represent the tem- perature in the first mixing space 150.

The controller 156 checks the temperature within the first mixing space 150, and if it detects that the temperature rises above or below predefined control temperature thresholds, it triggers feed of heat to the first mixing space, in the present embodiment this is done by implementing a control oper- ation in any of the feeds of sources 102, 104, 106. It is noted that the configuration shown in Figure 1 is exemplary, the controller 156 may implemented in various other ways, well known to a person skilled in the art. For example, control operations and logic of the controller may be implemented manually by the operator of the surface treatment device.

A lower threshold for the temperature range applied in the first mixing space is, according to the invention, defined to be higher than evaporation temperature of at least one liquid substance that carries at least one precursor of the applied surface treatment particles in the droplets within the first mixing space. Advantageously, but not mandatorily, the lower threshold is adjusted to ensure that substantially all liquid elements in the first mixing space evaporate and a dry aerosol flow 166 is achieved. In practical implementations, it has been detected that the advantageous drying and mixing effect has been achieved when temperatures on the outer surface of the casing are 50-100 degrees Celsius above the evaporation point of a substance that provides at least half of the volume of the liquid mix. In such conditions, the liquid sub- stances in the droplets evaporate and condensation of liquids on inner surfaces of the first mixing space is avoided.

The higher threshold is defined according to a number of requirements. It is understood that when temperature is raised, at some point the pressure of steam from the evaporating droplets begins to prevent penetration of heat to the droplets. Optimally heating of the first mixing space should be adjusted to avoid such evaporation conditions. In addition, when the casing 152 is continuously exposed to burning temperatures, it easily begins to deteriorate. In order to achieve uniform particle flow from the first mixing space, the structure in the outlet of the casing, must be robust and maintain its dimen- sions well also in continued use. The applied configuration should also allow preparation of the casing from economically viable refractory materials, like iron, steel and aluminium.

All these requirements are met by adjusting the higher threshold of the temperature range to a level that is well below the typical temperatures of flame-based particle synthesis processes, i.e. in the order of the rated operating temperatures of conventional metallic casing materials (steel, aluminium). The term rated operating temperature refers here to a material property of the casing and indicates a design value for operating temperatures of the material. This value is typically given by the manufacturer of the material or the casing and in practise corresponds to a maximum temperature in which the casing may be continuously and industrially applied. For optimal configurations, the higher threshold of the temperature range preferably does not exceed the rated operating temperature of the casing material, and is typically in the order of 10-500 degrees Celsius above the lower threshold. An example of applicable casing materials is heat resisting steel 353MA, the rated operating temperature of which is about 1000 degrees Celsius in air. In a temperature range well below 1000 degrees Celsius, advantageously below 800 degrees Celsius, the rated operating temperature of a heat resisting metal casing is not exceeded, the shape of the casing remains constant during use, and correspondingly the effect of the shape of the casing to the flow remains predictable even in industrial use. At the same time, optimal evaporation conditions are achieved and the main part of particle synthesis processes take place outside the first mixing space.

In typical implementations the liquid mixtures are solvents that evaporate in relatively low temperatures, and the temperature measured on the outer surface varies between 300-800 degrees Celsius. Within this temperature range typical liquid substances evaporate effectively, most of the particle generation processes do not yet take place and the casing providing the first mixing space can be produced from conventional inexpensive materials.

The burning temperatures of normal particle generating flames, like hydrogen-oxygen flames, are typically well above the temperature range applied in the first mixing space. When the evaporation is made by burning combustible substances in the first mixing space, in order to keep the temperature in a desired lower temperature range, the controller 156 may, for example, decrease flow from feed for the source 104 of the burning substances, and/or change the composition of burn control substances. Reduction in the amount of available oxygen within the confined first mixing space 150 effectively slows the burning process, and thereby decreases the temperature within the first mixing space. By decreasing the flow of combustible substances from the feed, or by reducing the proportion of oxygen in the flow from the feed the burning may be slowed down, causing the temperatures within the first mixing space to remain in the desired temperature range. Alternatively, burn control substances from feed 105 may be used to control the flame and cool the first mixing space to a desired temperature range.

Other means for controlling the temperature within the first mixing space may be applied within the scope. For example, the device may comprise a further cooling element (not shown) connected to the body of the casing 152 to deliver heat by conduction or convection away from the first mixing space. The controller 156 may comprise, or be connected to a conductive element that directs heat to the wall of the casing and thereby causes conduction of heat through the body of the casing 152 into the first mixing space. An additional flow of cooling gas may also be conducted into the first mixing space for the purpose.

Other means for providing evaporation of the droplets may also be applied. Electromagnetic radiation of various wavelengths, for example in form of microwaves or infrared light (gas laser) may be guided into the first mixing space to act on the droplets. In these embodiments, the source unit 100 does not need to provide combustible substances and/or burn control substances into the first mixing space 150.

Mixing of the inlet substances within the first mixing space 150 may be enhanced by form and design of the casing. In addition, separate flow con- trol elements (guides, gas flow injectors) may be arranged into the first mixing space 150.

The role of the thermal reactor 170 outside the first mixing space is to raise the temperature within the outcoming dry flow to particle generation temperatures, typically to temperatures above 1700 ^°C. In these higher tem- peratures, chemical reactions of the particle synthesis process may now take place. In the embodiment of Figure 1 , the thermal reactor comprises a flame 176 to which substances flowing out of the first mixing space are exposed. The speed of particles within the flame 176 increases and deposition of the particles on or in the treated surface of the substrate 178 intensifies. In some con- figurations, the high temperature gas / aerosol flow may heat the treated surface of an opposing substrate 178 such that particles within the flow can diffuse into the substrate 178. In the heat of the flame, the particle flow may reach temperatures where also thermophoresis assists deposition of the particles on the treated surface.

In the configuration of Figure 1 , the means for providing the thermal reactor comprises burners 172, 174 that subject the flow of particles 166 to a uniform oxygen (O₂) flow, which boosts the burning. Due to this, the temperature of the flame 176 raises to the higher levels applied in flame-based deposition processes.

The confined evaporation facilitates extraction of precursor particles from point sources and mixing them into a spatially uniform flow that extends throughout a larger scale outlet. The improved uniformity of the flow shows as improved uniformity of the resulting deposition. The configuration thus improves surface treatment results achievable with a point source. Furthermore, a number of point sources may be combined into one source configuration that feeds an extended process space where precursors of the point sources efficiently mix. This generates a uniform flow that may be output through a correspondingly extended outlet to deposit larger areas at one time.

Block charts of Figures 2A to 2C illustrate a configuration applicable for precursor flow generation in an embodiment of a surface treatment device where an extended uniform flow is used for surface treatment of larger-scale planar objects. Figure 2A shows a side view, Figure 2B a top view and Figure 2C a bottom view of the surface treatment device of the embodiment. In the embodiment, a plurality of point sources 20, 21 , 22, 23, 24 are arranged into a row. A casing 26 encloses a first mixing space 25 that extends into the direc- tion of the row and the row of point sources 20, 21 , 22, 23, 24 are connected to one side of the casing 26. In the opposite side of the casing there is an elongated, typically linear outlet 27. During use, each of the point sources feeds into the first mixing space 25 within the casing 26 a spray of atomised droplets. The droplets carry one or more precursors of particles used for deposition in the surface treatment device. According to the invention, liquid substances of the droplets are evaporated within the first mixing space 25 and efficiently mix into a flow that streams out of the linear outlet 27.

Figure 3 illustrates front and side views of a configuration in another embodiment of a surface treatment device according to the invention. The con- figuration is mainly the same as in Figure 1 , so basic information on elements may be referred from description of Figure 1 . In a configuration of Figure 1 , the size of the first mixing space advantageously matches with the size of the nozzle. For safety reasons one typically tries to minimise extensive volumes that comprise combustible substances. In the embodiment of Figure 3, precursor substances are atomized into separate first mixing spaces, flow adjustment chambers 30, 31 , 32, 33 and droplets are heated therein such that evaporation occurs and precursors carried by the droplets efficiently mix into a flow of gas and particles. The outlets of separate flow adjustment chambers 30, 31 , 32, 33 are conveyed into a shared deposition element 34. The deposition element is a chamber-like hollow casing that provides a second mixing space for flows from two or more first mixing spaces. The deposition element has an inlet side that incorporates the outlets of two or more first mixing spaces, and an outlet side that incorporates one or more openings from which substances in the deposition element may flow out. The outlet side is typically opposite to the inlet side, but the flows mix efficiently in the deposition element so other inlet-outlet side configurations may be applied, as well.

The relation between the two or more inlets and the one or more openings is arranged such that the incoming flows are constricted and thus forced to mix within the deposition element before they flow out of the deposi- tion element. In the exemplary embodiment of Figure 3, the inlet side of the deposition element is rectangular and provides a connection for the four flow adjustment chambers of four nozzles. During operation, each of the flow adjustment chambers feeds in a flow of gas and particles through a circular opening. In typical configurations, the distance between such circular openings is of the order of centimetres. The outlet side of the deposition element comprises an elongated opening, the area of which is considerably smaller than the area of the rectangular inlet side. As shown in the side view, the outlet side may be tapered such that the cross-section of the outgoing flow reduces on its way towards the opening. The tapering promotes creation of a uniform flow and at the same time may increase the velocity of the particles before they exit from the deposition element.

The mixture of substances flowing into the deposition element from the flow adjustment chambers has been controllably heated, so it is only weakly combustible or not combustible at all. They need to be mixed with accelerating substances that enable reaching the temperatures for efficient particle generation in the deposition element. Due to this, the deposition element comprises a number of accelerating substance inlets 35 that are connected to a reservoir of one or more accelerating substances (not shown). The type of accelerating substance depends on the selected method previously used for the controlled heating in the flow adjustment chamber. For example, if heating has been provided by burning, and burning in the flow adjustment chambers has been controlled by restricting availability of oxygen for the burning process, accelerating substance may comprise oxygen. If burning in the flow adjustment chambers has been restricted by availability of combustible substances in the flow, or if heating has been provided by some other way than burning, acceler- ating substance may comprise one or more combustible substances.

In any case, the accelerating substances are typically in gaseous form so inlet openings may typically be positioned with of the order of millimetre distances. As a comparison, distances between atomizing nozzles typically need to be in the order of centimetres. Due to the two-phased chamber struc- ture of the present embodiment, the combustible substances may be efficiently mixed with the aerosol that carries the precursors, and the advantage of improved flow composition is achieved. However, the volume where highly combustible gases are confined during mixing is much smaller than in the embodiment of Figure 1 . After exit from the deposition element, the mix of substances of the original flows from the flow adjustment chambers and the accelerating substances are ignited to form a flame that provides the thermal reactor where particles are generated. These particles are directed on a treated surface.

The embodiments of Figures 1 to 3 show a configuration where the liquid substances are evaporated from the droplets by means of controlled burning in the first mixing space. As discussed above, burning is, however, not mandatory for temperature control within the first mixing space. For a person skilled in the art it is clear that also other evaporation mechanisms may be applied for the purpose. For example, the casing may be equipped with heating means that conduct heat to the first mixing space and increase the tempera- ture within the first mixing space to such a level that the liquid substances within the droplets begin to evaporate. On the other hand, heated gas may be input to the first mixing space to increase the temperature of the combined mix of substances within the first mixing space reaches the desired temperature range. Heated gas may input as an atomizing gas used in the nozzle 108, or blown separately to the first mixing space via a specific feed of the nozzle 108. Electromagnetic radiation of various wavelengths, for example in form of microwaves or infrared light (gas laser) may be guided into the first mixing space to act on the substances and thereby increase temperature within the first mixing space. Evaporation in the surface treatment device may be implemented by means of one or more of such evaporation mechanisms.

The block chart of figure 4 illustrates a side view of a surface treatment device applying configurations disclosed above. The surface treatment device comprises conveying means 40 adapted to linearly transfer planar objects, like glass sheets, in a defined direction 41 . In Figure 4 the conveying means are shown as a roller conveyor with a plurality of successive rollers rotating in one direction. During operation, a planar object 42 positioned on the rotating rollers thus moves in the defined direction. It is noted that type of conveyor is not, as such, relevant for the invention. The roller conveyor is used here as an example of a variety of possible means that allow linear transfer of planar objects in a defined direction. Other corresponding conveying means may be applied without deviating from the scope of protection.

The surface treatment device of Figure 4 comprises also a particle generation unit 43 that applies the configuration shown in Figures 2A to 2C. The particle generation unit 43 comprises a source unit 44, a casing 45 and a burner unit 46. The source unit 44 is connected to the side of the casing that faces off from the planar object. The source unit 44 incorporates a row of point sources that spray droplets carrying precursor substances into the space confined within the casing 45. The precursor substances flow out of an elongated outlet 47 that is in the opposite side the casing and extends substantially to the width of passing planar objects. The particle generation unit comprises or is connected to evaporation means 47 that subject the droplets in the casing to heat. In the casing 45, the liquid substances of the droplets are evaporated and the confined space, together with the effect from the incoming and outgoing flows allows the precursor particles to mix and generate a spatially homogenous aerosol that flows uniformly out of the whole extent of the linear out- let 47. The burner unit 46 comprises one or more burners that generate a flame 48 that increases the temperature in flow of particle precursors for completion of the particle generation process.

The conveying means 40 and the particle generation unit 43 are mutually positioned so that during use the flame extends towards planar ob- jects travelling on the conveying means such that substances and particles coming out of the flame are impacted on a surface of a passing planar object. Preferable deposition and collection zones may be easily adjusted according to the deposited particles, depositing processes and/or treated surface materials.

The configuration of the embodiment allows quick and effective coating for planar objects. The resulting coating is much more uniform than coatings achieved with any of the prior art configurations.

Figure 5 illustrates a side view of another embodiment of a surface treatment device. Similar to Figure 4, the surface treatment device of Figure 5 comprises conveying means 50 that during operation moves planar objects 52 in a defined direction 51 . The surface treatment device comprises also a particle generation unit 53 that applies the configuration shown in Figure 3. The particle generation unit 53 comprises a source unit 54 and a casing 55. The source unit 54 incorporates a nozzle through which atomized droplets carrying precursor substances are sprayed into a first mixing space in the casing 55. In addition, the particle generation unit comprises, or is connected to evaporation means 57 that subject the droplets that are in the casing to heat.

In the surface treatment device of Figure 5, advantageously one source unit 54 feeds one separate casing 55 and separate casings are arranged into a line such that openings of the casings in the line form an elon- gated row of separate outlets. The particle generation unit comprises also a deposition element, a deposition chamber 56 into which the row of openings of the casings in the line feed a mix of gas and precursor substances. The deposition chamber 56 is connected to a reservoir 59 that feeds accelerating substance into the deposi- tion chamber. The accelerating substances mix with the mix of gas and precursor substances and flow out as a highly combustible mix of substances. Outside the deposition chamber 56 the flow is ignited into an elongated flame 58 that provides the thermal reactor where particle generation occurs. During use the elongated flame extends towards planar objects travelling on the con- veying means such that substances and particles coming out of the flame are deposited on a surface of a passing planar object. Preferable deposition and collection zones may be easily adjusted according to the deposited particles, depositing processes and/or treated surface materials.

Figures 4 and 5 illustrate generation of particles by flames 48, 58 and deposition of generated particles on substrates 42, 52 in view of the embodiments of the present invention. For a person skilled in the art it is clear that the deposited particles may create a layer of material on the substance, or they may adhere or attach to the treated surface in many ways and even diffuse into a layer of the substrate matrix. In addition, the surface treatment device may comprise further processing elements to complement and/or enhance the results created by the processes described above. For example, the particles generated in the first flame 48, 58 may be deposited on the surface and subsequently exposed to a second heat treatment that sinters the generated particles into a layer to the surface of the treated substrate. A surface treatment device may thus comprise first means for providing a primary flame for generating and depositing a layer of particles on a substrate, and second means for providing a heat treatment that sinters the layer of particles on the substrate.

Figure 6 illustrates stages of an embodiment of a corresponding surface treatment method. Additional generic information on the stages may be referred from Figures 1 to 5. Figure 6 shows stages of the method for one set of process materials, but it is clear that in industrial processes the stages are continuously performed for continuously running feeds of materials. The procedure of Figure 6 begins in the state where the surface treatment is in operative condition and encloses an impermeable first mixing space FMS.

Atomised droplets of a liquid substance carrying one or more precursors of the defined particles are input (stage 60) into a casing that encloses an impermeable first mixing space FMS. The droplets within FMS are exposed some form of heat transfer (preburning, heating, radiation) that evaporates (stage 61 ) the liquid substance of the droplets within FMS. During evaporation, the precursors move within FMS, efficiently mix and form a uniform aerosol flow. A resulting aerosol flow that carries the precursors of the defined particles is output (stage 62) from FMS.

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

1. A surface treatment device for directing defined particles towards a substrate, c h a r a c t e r i z e d by comprising:

a casing (152) providing a first mixing space (150);

a source unit (100) for inputting into the first mixing space atomised droplets of a liquid substance carrying one or more precursors of the defined particles;

an evaporation mechanism (104, 150, 156) for evaporating at least one liquid substance from the droplets within the first mixing space,

the casing comprising an outlet (154) for outputting a particle aerosol flow carrying the precursors of the defined particles from the first mixing space (150).

2. A surface treatment device according to claim ^characterized by comprising means (170) for providing a flame for a flame-based particle synthesis process (176) into which the aerosol flow carrying precursors of the defined particles is output.

3. A surface treatment device according to claim 2, character- i z e d by

the casing (152) comprising an inlet and the outlet (154), the source unit (100) being connected to the inlet of the casing (152);

a burner unit (170) connected to the outlet (154) of the casing.

4. A surface treatment device according to any of claims 1 to 3, characterized in that the casing (150) is detached from ambient environment outside the casing such that fluids do not substantially enter or exit the first mixing space through the casing.

5. A surface treatment device according to claim 3 or 4, characterized in that the evaporation mechanism (104, 150, 156) is config- ured to control burning of substances within first mixing space.

6. A surface treatment device according to any of claims 1 to 5, characterized in that the evaporation mechanism (104, 150, 156) comprises a control mechanism (156, 160) for limiting temperature within the first mixing space according to temperatures measured in an inner or an outer surface of the casing (152).

7. A surface treatment device according to claim 6, character- i z e d in that the evaporation mechanism (104, 150, 156) comprises a control mechanism (156, 160) for limiting temperature within the first mixing space such that the temperature measured in the inner or outer surface of the casing is above the evaporation temperature of the liquid substance and below 800 degrees Celsius.

8. A surface treatment device according to claim 6, characterize d in that the evaporation mechanism (104, 150, 156) comprises a control mechanism (156, 160) for limiting temperature within the first mixing space such that measured in the inner or outer surface of the casing is in a range of 300 to 600 degrees Celsius.

9. A surface treatment device according to any of claims 3 to 8, characterized in that the evaporation mechanism (104, 150, 156) comprises means for evaporating the liquid substance of the droplets within the first mixing space by heat transferred through the casing, by a flow of heat- ed input in the casing, or by directing electromagnetic radiation to the first mixing space.

10. A surface treatment device according to any of claims 1 to 9, characterized by comprising a plurality of point sources (20, 21 , 22, 23, 24) arranged into a linear row and connected to one elongated first mixing space.

11. A surface treatment device according to any of claims 1 to 9, characterized by comprising a particle generation element with two or more separate first mixing spaces (30, 31, 32, 33) and a second mixing space (34) into which aerosol flows of the two or more first mixing spaces (30, 31 , 32, 33) are output.

12. A surface treatment device according to claim 11, characterized in that the second mixing space comprises at least one inlet (35) that is connected to a reservoir of one or more accelerating substances.

13. A surface treatment device according to claim 11 or 12, characterized in that the second mixing space comprises an elongated outlet.

14. A surface treatment device according to claim 10 or 13, characterized by comprising conveying means (30) adapted to linearly transfer planar objects in a direction (31) traverse to the linear row or traverse to the elongated outlet.

15. A surface treatment device according to claim 11, c h a r a c - t e r i z e d in that the device is configured to treat surfaces of glass sheets.

16. A surface treatment method, comprising:

depositing defined particles on a substrate, characterized by:

inputting (40) atomised droplets of a liquid substance carrying one or more precursors of the defined particles into a casing enclosing an impermeable first mixing space;

evaporating (41) the liquid substance of the droplets within the first mixing space;

outputting (42) a particle aerosol flow carrying the one or more precursors of the defined particles from the first mixing space.

17. A method according to claim 16, characterized by out- putting the aerosol flow carrying precursors of the defined particles into a flame of a flame-based particle synthesis process.

18. A method according to claim 17, c h a r a c t e r i z e d by limiting temperature within the first mixing space according to temperatures measured in an inner or an outer surface of the casing.

19. A method according to claim 18, characterized by limiting temperature within the first mixing space such that the temperature meas- ured in the inner or outer surface of the casing is above the evaporation temperature of the liquid substance and below 800 degrees Celsius.

20. A method according to claim 19, characterized by limiting temperature within the first mixing space such that measured in the inner or outer surface of the casing is in a range of 300 to 600 degrees Celsius.

21. A method according to claim 16, characterized by evaporating the liquid substance of the droplets within the first mixing space by heat transferred through the casing, by a flow of heated input in the casing, or by directing electromagnetic radiation to the first mixing space.

22. A method according to any of claims 16to21, character- i z e d by the substrate being a sheet of glass.