CA2464340A1 - Coating precursor and method for coating a substrate with a refractory layer - Google Patents

Abstract

The invention concerns coating precursor comprising a silicone resin, a mineral filler and an organic solvent capable of dissolving said resin and suspending the mineral filler, said silicone resin and said mineral filler being capable of chemically reacting so as to produce a solid layer on a substrate after the organic solvent has evaporated and a cohesive refractory layer after a calcination process. The invention also concerns a method for coating a specific surface of a substrate with at least a cohesive refractory silicone-containing layer which consists in coating the substrate with a coating precursor of the invention, so as to form a raw layer and in carrying out a heat treatment so as to calcine said raw layer and form a cohesive refractory layer. The invention enables to obtain a protective coating resistant to oxidizing surroundings, liquid metal or a solid or molten salt.

Description

COATING PRECURSOR AND METHOD FOR COATING A
SUBSTRATE OF A REFRACTORY LAYER
Field of the invention The present invention relates to the protection of objects and materials intended at the metallurgical industry, especially the aluminum industry. She concerns in particularly the protective coatings of said objects and materials.
State of the art The objects and materials that are used in the aluminum industry are often exposed to corrosive environments and subjected to high temperatures and of the significant thermal constraints. Containers (such as bags or ovens), the conduits (such as the chutes, the injectors and the nozzles of casting) and tools and devices that are used to handle and process aluminum liquid (such filters and rotors) must be very resistant mechanical and chemical. In particular, the surfaces of these objects that are exposed to aluminum liquid must neither dissolve nor contaminate the liquid aluminum.
Although the resistance of materials commonly used in the industry aluminum is generally sufficient, there are certain applications or conditions for which an even greater resistance is sought. It is the case in particular when one seeks to reduce to a practically zero value the number of inclusions contained in each ton of aluminum cast.
The applicant has therefore sought means which make it possible to manipulate, develop, process and cast aluminum and aluminum alloys liquids satisfactorily under the most demanding conditions and applications demanding.

2 Description of the invention The subject of the invention is a coating precursor intended for training a protective layer on a substrate. Said precursor comprises a resin silicone and a mineral filler capable of reacting chemically with said resin so as to produce a cohesive refractory layer after a calcination operation of the layer.
More precisely, the invention relates to a coating precursor comprising a silicone resin (or organosiloxane), a mineral filler and a solvent organic able to dissolve said resin and suspend said charge mineral, said silicone resin and said mineral filler being capable of reacting chemically with so as to produce a solid layer on a substrate after evaporation of the solvent organic and a cohesive refractory layer after an operation of calcination.
Said precursor is preferably homogeneous.
The silicone resin is a polysiloxane preferably comprising a proportion of OH groups, such as a polymethylsiloxane, a polydimethylsiloxane, a polymethylsilsesquioxane, or a mixture thereof, comprising a proportion of OH groups substituted for methyl groups. The Applicant noted that the proportion of OH groups is preferably between approximately 0.5%
and about 2%. Too small a proportion of OH groups does not confer a sufficient propensity to form a solid layer after evaporation of the solvent and to strong cohesiveness after calcination. A proportion of OH groups very high can make polysiloxane difficult to produce at an acceptable cost. The silanol groups (Si-OH) are preferably stable in order to allow the resin storage. These OH groups can be grafted to a polysiloxane by hydrolysis. The siloxane units of the polysiloxane according to the invention are advantageously, in whole or in part, tri- or quadri-functional.

3 The organic solvent is typically an apolar solvent, such as xylene or a toluene. Xylene can be a mixture of different types of xylene, such as that o and p.
The mineral filler is typically chosen from borides, carbides, the nitrides and oxides of metals or among borides, carbides and nitrides of non-metals (such as boron nitrides), or a combination or mixture of them. Said mineral filler is advantageously chosen from the compounds of metal such as metal oxides, metal carbides, borides of metal and them metal nitrides, or a combination or mixture thereof. Load mineral is preferably able to react chemically with the silicone resin of way to produce a solid layer after evaporation of the organic solvent and a layer high cohesive refractory after calcination of said raw layer. The charge mineral can be chosen according to the physico-chemical characteristics expected from the coating (such as wettability or non-wettability by a metal liquid).
The metal compound is advantageously alumina, Zr02, ZrB2, TiB2 or TiO2 or a combination or mixture thereof. Alumina is preferably a reactive calcined alpha alumina, called technical alumina, of which the rate hydration is very low (typically less than 1%, or even less than 0.5%).
The mineral filler is preferably in the form of a fine powder, this who provides a fluid precursor and a uniform coating. It is typically added to the silicone resin / organic solvent mixture after a grinding end. The particle size of the mineral filler powder is typically such that the grain size is between 0.05 ~ m and 50 ~, m.
The physical properties of the coating, such as its mechanical properties, can, in some cases, be adapted by adjusting the proportion of charge mineral and / or its particle size.

4 According to a preferred embodiment of the invention, the precursor occurs typically in the form of a suspension or slip. It is typically obtained by mixing the resin, the mineral filler and the solvent organic.
In this embodiment, the proportion of silicone resin in the precursor is typically between 5 and 30% by weight, and preferably between 7.5 and 20% in weight, in order to allow satisfactory ceramic coating of the coating during the calcination. Excluding solvent, the proportion of silicone resin in the precursor East typically between 15 and 40% by weight.
The proportion of organic solvent in the precursor is then typically between 7.5% and 60% by weight, and preferably between 15 and 30% by weight.
The amount of solvent is preferably such that all of the silicone resin East dissolved and the solution obtained is capable of suspending the charge mineral.
The proportion of mineral filler in the precursor is typically understood Between 30% and 75% by weight, and preferably between 45 and 70% by weight. A
proportion too weak leads to too fine deposit and therefore requires deposit of a big number of successive layers. Too large a proportion precursor which is difficult to spread.
According to another preferred embodiment of the invention, the precursor is present typically in the form of a paste.
In this embodiment, the proportion of silicone resin in the precursor is then typically between 7.5 and 20% by weight, and preferably between 10 and 17.5% by weight, in order to allow satisfactory ceramization of the coating when calcination.
The proportion of organic solvent in the precursor is typically understood between 2.5% and 10% by weight.

WO 03/03343

5 PCT / FR02 / 03515 S
The proportion of mineral filler in the precursor is typically understood Between 70% and 95% by weight, and preferably between 75% and 90% by weight.
In this embodiment, the coating precursor comprises advantageously an additive capable of reducing the viscosity of the precursor. Said additive includes typically a dispersant, such as stearic acid. The proportion of said additive in the precursor is typically less than 2% by weight, and more typically between 0.1 and 1%.
The precursor is typically obtained by mixing the resin, the filler mineral and additive and, if necessary, by grinding the mixture.
The invention also relates to a method for coating a surface.
determined of a substrate of at least one refractory layer containing silicon in which - The substrate is coated with a coating precursor according to the invention, way to form a raw layer;
- a thermal treatment, called calcination, is carried out, capable of entraining elimination of volatile matter, calcination of said raw layer and the formation of a cohesive refractory layer.
The Applicant has observed that the process of the invention makes it possible to obtain a resistant and strongly adherent thin layer to the substrate which resists well to metal liquid and which has a strong cohesiveness.
The coating precursor can be prepared in at least two operations - a silicone resin is dissolved in an organic solvent, so as to get a silicone resin solution;
- the mineral filler is added to the silicone resin solution as well obtained.
The coating of the substrate (which typically includes depositing and spreading said precursor on the substrate) can be carried out by any known means. Through example the

6 coating can be applied by brushing (typically using a brush and / or a roller), by soaking, spraying, or spraying (typically using a pistol). ~ Basting, soaking and spraying are particularly suitable for depositing precursors in the form of a suspension or of slip. The projection is particularly suitable for the deposition of precursors under paste form. The substrate can optionally be brought to a temperature above ambient before coating in order to promote the formation of a deposit homogeneous and the adhesion of the deposit by fusion of the resin.
The method according to the invention can also include operations complementary, such as a preparation of the parts of the surface of the substrate that we try to coat and / or dry the raw coating before treatment thermal. Said drying is used in particular to evaporate said organic solvent and at solidify, at least partially, the raw layer (so that manipulate the substrate without altering the layer). Preparation of the substrate surface comprises typically cleaning and / or degreasing (e.g. using acetone).
In some applications, it may be advantageous to use a precursor of.
coating further containing a wetting agent capable of promoting formation a thin layer. This is particularly the case with certain screen filters, look for cover the wires with the wire mesh without blocking the openings. said agent wetting agent is preferably a polyether silane, which promotes spreading of the coating on the substrate without preventing the ceramic coating refractory during heat treatment. The chemical formula of said polyether silane is typically /GOLD
CH3-O- (CHa-CH2-O-) io-CH2_CHa_CHa_Si_O_R
\GOLD
where R is an alkyl group, typically methyl.
Advantageously, the wetting agent also makes it possible to avoid or delay substantially the solidification of the precursor.

7 The proportion of wetting agent in the precursor is typically between 1 and 5 in weight approximately, and preferably between 2 and 4% by weight for the precursors in the form of a slip or suspension and between 2 and 5% by weight for the precursor in paste form.
The so-called calcination heat treatment comprises at least one step at a high temperature, which is typically between 650 and 1300 ° C, and more typically between 800 and 1300 ° C, able to transform the raw layer into a refractory ceramic, which is advantageously in the vitreous state. The composition of the glassy phase typically comprises between 5 and 25% by weight of silica obtained of the resin (the rest, typically 75 to 95% by weight, is essentially made of mineral filler). The calcination temperature also depends on the substrate;
for example, in the case of a metallic substrate, it is advantageously lower at the softening temperature thereof. On the other hand, .it ~ is also better to use a calcination temperature higher than the temperature of use of the coated substrate. The heat treatment may include a step intermediate at a temperature between 200 and 600 ° C
(typically between 200 and 250 ° C). This intermediate step is preferably capable of causing crosslinking of the resin and, possibly, the decomposition thereof before the "
ceramization »
(or final calcination) of the coating. In this case, it is possible, according to a variant advantageous of the invention, to continue the heat treatment of calcination in situ, i.e. when using the substrate at high temperature (this temperature advantageously being greater than 650 ° C.).
The duration of the heat treatment is advantageously such that it allows a complete ceramization of the precursor. The temperature rise is preference slow enough to prevent cracking of the coating.
During the heat treatment, organic compounds are removed (by evaporation and / or by decomposition), leaving on a surface of the substrate a solid refractory. This solid is for example formed from the metal coming from the compound oh of metal and silicon from the silicone resin. In the case of alumina, the Si-OH silanol groups of the polysiloxane seem to establish bonds covalent with the OH groups of alumina, which bonds seem to himself transform into Si-O-Al bonds, with release of water, during treatment thermal, to form an alurnino-silicate, which is advantageously in the state glassy.
A similar mechanism could occur with other metal compounds than alumina.
The ambient atmosphere during the calcination treatment is advantageously no-oxidizing, in particular to avoid oxidation of the substrate at the interface substrate /
coating likely to cause decohesion between the substrate and the coating, or even the destruction of the subsirate (for example when it is in graphite).
The final coating may comprise two or more successive layers, who can be applied by successive coatings and heat treatments, ie by successive coating / heat treatment sequences. In others terms we repeats the operations of coating and calcination treatment of the layer for each elementary layer of the final covering. The successive layers can have a different composition, so as to give them properties different chemical and mechanical. This last variant makes it possible to adapt each layer has a local function, such as adhesion to the substrate for the first layer, mechanical resistance for the intermediate layers. and the chemical resistance for the surface layer.
The invention also relates to a substrate of which at least part of the area comprises at least one refractory layer obtained using said precursor or in using said coating process, which refractory layer is advantageously in the glassy state, with or without a composition gradient in the direction perpendicular to the surface of the substrate.
The invention also relates to the use of said precursor or of said process of coating for the protection of a substrate, in particular for the protection of a material and / or piece of equipment intended to be exposed to a environment oxidizing agent, to liquid metal (in particular aluminum, an aluminum alloy, of magnesium or a magnesium alloy, in the liquid state) and / or a solid salt or in fusion.
The term substrate must be understood in the broad sense: the substrate can be metal (such than an iron-nickel-chromium base alloy (typically steel or Inconel)), refractory material or carbonaceous material (such as graphite), or a mix or a combination of these; it can be a particular object (typically a piece equipment, such as a metal or refractory component of a casting, a nozzle, a distributor of liquid metal in a swamp, a sieve in steel (especially stainless steel) or refractory material or ceramic, a metal or refractory filter, a liquid metal or bubble injector gas, a rotor; doctor blade, pouring spout, ultrasonic sensor, measurement sensor (ultrasound, temperature, ...) intended to be immersed in a liquid metal, the pieces materials carbonaceous, eri graphite bricks, etc.), or a material, in particular a material of coating (such as a brick of refractory material or carbonaceous material (such as graphite)). The substrate can be porous or non-porous.
testing Several tests have been carried out on different substrates. These attempts were made at using the following components ~ Mineral fillers - a calcined alpha alumina powder (technical alumina reference P172SB
from the company Aluminum Pechiney) having a D5o of 0.5 ~, m and a surface specific BET from 6 to 8 malg. The alumina was finely ground (particle size typically between 0.2 ~, m and 1.5 gym);
- a ZrOa powder (reference CS02 from Saint-Gobain) having a D5o of 0.8 ~ .m and a BET of 5.5 m2 / g;

- a Ti02 powder (reference Kemira UV Titan P 370) whose grains have a size of 0.06 ~, m;
- a TiB2 powder (reference Metabap 143) having a D50 of 1.7 ~, m;
5 ~ Silicone resin: a polymethylsiloxane MK from the company Wacker, which is a tri-functional resin with approximately 1% of OH groups. This resin was composed of approximately 80% of silica equivalent and 20% of methyl groups, which himself decompose at a temperature of the order of 450 ° C;
10 ~ Organic solvent: xylene;
~ Wetting agent: a Dynasylan polysilane ~ 4140 from the company Dégussa-Hüls (about 3% by weight based on the amount of metal compound in all the case).
Slip test series Several slip compositions have been tested. They had the compositions given in Table I (% by weight). The proportions were such that the refractory lining obtained comprised approximately 80% by weight of equivalent of the compound of metal (or mixture of metal compounds) and 20% by weight equivalent silica. The concentration of silicone resin in xylene was from 250g / 1 about.
Table I
Component nln 2 n 3 n 4 n 5 n 6 Alumina 44.9 - - 35.9 - -(A1203) Zirconia - 44.9 - - - -(Zr02) Oxide - - 30.2 - - -titanium (Ti02) Diboride - - - 9 44.9 66.0 of titanium (TiB2) Resin 14 14 9.4 14 14 11.2 silicone Solvent 39.8 39.8 59.4 39.8 39.8 22.8 organic Agent 1.35 1.35 0.9 1.35 1.35 wetting The xylene was mixed so as to obtain a homogeneous mixture. Resin silicone was dissolved at room temperature in this organic solvent until obtain a homogeneous solution. If necessary, the wetting agent was then added to this solution. After a ripening time of 10 minutes, the charge was added to this solution and mixed (by shaking) until a suspension is obtained homogeneous.
Several tests have been carried out on a 304 L stainless steel mesh as long as substrate. The wire diameter of this mesh was 100 ~ .m and the mesh of 200 ~ .m.
The substrate has been previously cleaned with a solvent capable of degrease them surfaces, especially acetone. In some tests, roasting has also been soaked in a sodium hydroxide solution (for example 60 g / 1 at room temperature).
The slip was deposited in a thin layer on the substrate by painting (to using a brush and a roller so as to clear the mesh). The substrate coated with then left in the open air for a few minutes so that the solvent can s'waporer.
It was observed that the layer dried quickly and that the deposit adhered firmly to the substrate (the deposit was very uniform and hard and allowed a easy handling of mesh). The percentage of closed meshes was low (typically less of 10 %). , After the drying operation, the slip coated substrate was subject to one hour heat treatment at a temperature of 900 ° C. .
Typically, the coating was obtained by depositing and baking four layers thin and successive uniforms. The excess precursors of each deposit have summer removed in order to avoid the appearance of adhesion defects. The final thickness of coating was typically in the range of 50 ~ .m. This coating was very uniform and solid (highly cohesive and non-pulverulent) and did not block openings of wire mesh (the mesh was only reduced to around 100 ~, m).
Screens thus coated were soaked for two hours in aluminum liquid at a temperature between 700 and 800 ° C. This test did revealed none deterioration of the coating.
Screens thus coated were used to filter aluminum liquid. This is has shown that these gratings allow the circulation of liquid aluminum without loss excessive load and without degradation of the coating. The obtained results for the initial flows on an area of around 13 cm2 are grouped in the table II.
These results show that the metal flow rate is high with all the slips tested.
Table II
Slip n 1 n 2 n 3 n 4 n 5 Initial flow 0.011 0.017 0.045 0.05 0.19 (Kg / s) The few tests carried out with a slip similar to the slip # 5, but without wetting agent, gave results comparable to those obtained with the # 5 slip. # 6 slip produced similar flow rates.
to those obtained with slip # 1 to 5.

Dough test series A dough composition was tested. She had the composition next (% ~
by weight): 82% mineral filler (alumina), 13.9% silicone resin and 4.1 organic solvent. The proportions were such that the coating refractory obtained included about 80% by weight equivalent of the metal compound ('or of mixture of metal compounds) and 20% by weight of silica equivalent. The compositions did not include a wetting agent.
The paste obtained was deposited on a metal substrate (a blade) of steel 304 L stainless steel using a spatula.
After the drying operation, the coated substrate was crosslinked to a temperature of 240 ° C for one hour, then baked at a temperature of 800 ° C.
The final coating thickness was typically in the range of 200 to 300 ~ M. This coating was very uniform and solid (high cohesiveness and non-powder).

Claims (49)

1. Coating precursor comprising silicone resin, filler mineral and an organic solvent capable of dissolving said resin and suspending the mineral filler, the silicone resin and the mineral filler being intended to react chemically so as to produce a solid layer on a substrate after evaporation of the organic solvent and a cohesive refractory layer after a calcining operation, the silicone resin being a polymethylsiloxane or a polymethylsilsesquioxane, or a mixture thereof, comprising a proportion of 4H groups substituted for methyl groups included between about 0.5% and about 2%. 2. Coating precursor according to claim 1, characterized in that them siloxane units of the silicone resin include tri- or quadri-units functional. 3. Coating precursor according to claim 1 or 2, characterized in that that said organic solvent is apolar. 4. Precursor according to claim 3, characterized in that the solvent organic apolar is a xylene or a toluene. 5. Coating precursor according to any one of claims 1 to 4, characterized in that the mineral filler is chosen from oxides of metal, metal and non-metal carbides, metal and non-metal borides and them metal and non-metal nitrides, or a combination or mixture thereof this. 6. Coating precursor according to claim 5, characterized in that the mineral filler includes a calcined alpha alumina. 7. Coating precursor according to claim 5 or 6, characterized in that that the mineral filler is chosen from the group comprising ZrO2, ZrB2, TiB2, TiO2, boron nitride, and a mixture or combination thereof. 8. Coating precursor according to any one of claims 1 to 7, characterized in that the mineral filler is in the form of a powder of which the grain size is between 0.05 µm and 50 µm. 9. Coating precursor according to any one of claims 1 to 8, characterized in that said coating precursor further contains a agent wetting capable of promoting the formation of a thin layer. 10. Coating precursor according to claim 9, characterized in that said wetting agent is a polyether silane. 11. Coating precursor according to one of claims 9 or 10, characterized in that the proportion of wetting agent in the precursor is between 1 and 5%
in weight. 12. Precursor according to any one of claims 1 to 11, characterized in this whether it is in the form of a suspension or a slip. 13. Precursor according to claim 12, characterized in that the proportion of solvent in the precursor is between 7.5% and 60% by weight. 14. Precursor according to claim 12, characterized in that the proportion of solvent in the precursor is between 15% and 30% by weight. 15. A coating precursor according to any one of claims 12 to 14, characterized in that the proportion of silicone resin in the precursor is between 5 and 30% by weight. 16. A coating precursor according to any one of claims 12 to 14, characterized in that the proportion of silicone resin in the precursor is between 7.5 and 20% by weight. 17. Precursor according to any one of claims 12 to 16, characterized in this that the proportion of mineral filler in the precursor is between 30 %
and 75% by weight. 18. Precursor according to any one of claims 12 to 16, characterized in this that the proportion of mineral filler in the precursor is between 45 %
and 70% by weight. 19. Precursor according to any one of claims 1 to 11, characterized in this that it comes in the form of a paste. 20. Precursor according to claim 19, characterized in that the proportion of solvent in the precursor is between 2.5% and 10% by weight. 21. Precursor according to claim 19, characterized in that the proportion of solvent in the precursor is between 10% and 17.5% by weight. 22. A coating precursor according to any one of claims 19 to 21, characterized in that the proportion of silicone resin in the precursor is between 7.5 and 20% by weight. 23. A coating precursor according to any one of claims 19 to 21, characterized in that the proportion of silicone resin in the precursor is between 10 and 17.5% by weight. 24. Precursor according to any one of claims 19 to 23, characterized in this that the proportion of mineral filler in the precursor is between 70 %
and 95% by weight. 25. Precursor according to any one of claims 19 to 23, characterized in this that the proportion of mineral filler in the precursor is between 75 %
and 90% by weight. 26. Precursor according to any one of claims 19 to 23, characterized in this that it further comprises an additive capable of reducing the viscosity of the precursor. 27. Precursor according to claim 26, characterized in that the additive includes a dispersant, such as stearic acid. 28. Precursor according to claim 26 or 27, characterized in that the proportion of additive in the precursor is less than 2% by weight. 29. Precursor according to claim 27 or 28, characterized in that the proportion of additive in the precursor is between 0.1 and 1% by weight. 30. Process for coating a specific surface of a substrate with at least one refractory layer containing silicon in which:
- said surface is coated with a coating precursor according to one any of claims 1 to 18, so as to form a green layer;
a heat treatment, called calcination, capable of causing removing volatile materials, calcining said green layer and the formation of a cohesive refractory layer. 31. Process according to claim 30, in which the coating is carried out by brushing, dipping or spraying. 32. Process for coating a determined surface of a substrate with at least one refractory layer containing silicon in which:
- said surface is coated with a coating precursor according to one any of claims 19 to 29, so as to form a green layer;
- a heat treatment, called calcination, capable of causing removing volatile materials, calcining said green layer and the formation of a cohesive refractory layer. 33. Process according to claim 32, in which the coating is carried out by projection. 34. A method according to any one of claims 30 to 33, wherein the substrate is brought to a temperature above ambient before the coating. 35. A method according to any one of claims 30 to 34, wherein said calcining treatment comprises at least one step at a temperature between 650 and 1300°C capable of transforming the raw layer into a refractory ceramics. 36. A method according to any one of claims 30 to 35, wherein said heat treatment includes an intermediate step at a temperature between 200 and 600°C. 37. A method according to any one of claims 30 to 36, wherein said Calcining treatment is carried out in a non-oxidizing atmosphere. 38. A method according to any one of claims 30 to 37, wherein said refractory layer is formed by several successive layers. 39. Method according to any one of claims 30 to 38, characterized in that said substrate is made of metal, refractory material or carbonaceous material, or one mixture or combination thereof. 40. Method according to claim 39, characterized in that said metal is an alloy iron-nickel-chrome base. 41. A method according to any one of claims 30 to 38, wherein said substrate is chosen from the group comprising metallic components or refractories of a casting loom, nozzles, metal dispensers liquid in a swamp, sieves made of steel, stainless steel, material refractory or ceramic, metal filters, filters made of refractory material, them liquid metal injectors, gas bubble injectors, rotors, doctor blades, pouring spouts, ultrasonic sensors, measurement sensors intended for be immersed in a liquid metal, the bricks made of refractory material, the parts in carbon materials and graphite bricks. 42. Use of the precursor according to any one of claims 1 to 29 or method according to any one of claims 30 to 41 for the protection of a material and/or piece of equipment intended to be exposed to a oxidizing environment, liquid metal and/or solid or molten salt. 43. Use according to claim 42, characterized in that said material is a metal, refractory or carbonaceous material, or a mixture or combination of these. 44. Use according to claim 43, characterized in that said metal is a iron-nickel-chromium base alloy. 45. Use according to claim 42, characterized in that said piece is selected from the group comprising metallic or refractory components of a casting loom, the burettes, the distributors of liquid metal in a marshes, sieves made of steel, stainless steel, refractory material or ceramics, metallic filters, filters made of refractory material, injectors of liquid metal, the gas bubble injectors, the rotors, the doctor blades, the beaks pourers, ultrasonic sensors, measurement sensors intended to be immersed in a liquid metal, the bricks in refractory material, the parts in carbon materials and graphite bricks. 46. Substrate characterized in that at least a part of the surface comprises at least at least one refractory layer obtained by using a precursor according to one any one of claims 1 to 29 or using the method according to one any of claims 30 to 41. 47. Substrate according to claim 46, characterized in that it is made of metal, in refractory material or carbonaceous material, or a mixture or combination of these. 48. Substrate according to claim 47, characterized in that said metal is an alloy iron-nickel-chrome base. 49. Substrate according to claim 46, characterized in that it is chosen from the groupa comprising the metallic or refractory components of a craft of casting, burettes, distributors of liquid metal in a swamp, sieve made of steel, stainless steel, refractory material or ceramic, the filters metal, filters made of refractory material, metal injectors liquid, the gas bubble injectors, rotors, scrapers, spouts, sensors ultrasound, measurement sensors intended to be immersed in a metal liquid, bricks made of refractory material, parts made of carbonaceous materials and graphite bricks.