DE102008019785A1 - Production of a corrosions-stable gas-tight coating used as an anti-adhesion coating comprises applying a primer layer with corrosion protection properties and a covering layer with high temperature anti-adhesion properties on a substrate - Google Patents

Abstract

Production of a corrosions-stable gas-tight coating comprises applying a primer layer with corrosion protection properties and a covering layer with high temperature anti-adhesion properties on a substrate. The primer layer contains ceramic and/or glassy particles and also 10-90 wt.% reactive components selected from metals, metalloids or salts which react with gases to form non-volatile reaction products during sintering at 370-1500[deg] C. The covering layer contains solids with high temperature anti-adhesion properties and ceramic hard materials and an inorganic or inorganic-organic binder.

Description

The The invention relates to a method for producing a corrosion-resistant, gas-tight coating and the use of the coating.

In Reactors and incinerators, for example in stone or Lignite-fired power plants and in biomass and waste incineration plants several components, for example parts of the boiler such as heat exchanger tubes, Steel tube aggregates or peripheral devices exposed to various attacks, which have a lasting negative impact on their functioning. So leads especially in steel tube aggregates and heat exchanger tubes the combination of high temperatures and the presence of corrosive Gases, such as chlorine and hydrogen chloride, as well as corrosive solids the problem of scaling and ultimately catastrophic Damage due to corrosion. An even bigger one Problem in reactors and incinerators is that during operation, in particular in waste incineration plants, on the said facilities or on the refractory lining, segregating corrosive solids and ashes adhering to the Heat transfer from the combustion chamber to the heat exchanger tube wall can inhibit significantly. Put these deposits a big problem since they are in regular Distances must be removed, either during the operation, for example by means of water lances or so-called Sootblowers or more frequently during downtime, in particular by mechanical removal by means of sandblasting, Brushing or by means of a pneumatic hammer. All these procedures are very expensive, damage the underlying substrate and are associated with high costs. Cleaning at standstill requires in addition to the high downtime the plant also highest security measures for the cleaning service.

To the Protection against these attacks may be such devices For example, with refractory masses, concretes or stones clad become. It can also corrosion-resistant ceramics, metals or Alloys are applied (so-called nickel cladding, thermal Spraying or welding process). These procedures are however extremely expensive, time-consuming, großflä chig not Applicable and can only be used in certain accessible Areas of reactors and incinerators become.

To solve the caking problems was in the EP 1 386 983 A a boron nitride-containing non-stick coating proposed both for the steel pipe aggregates directly and for the refractory pipe wall panels, which significantly reduces the deposits described and thus ensures a uniform heat transfer in the long term. The likewise in the EP 1 386 983 A proposed coating composition for producing such layers has in particular boron nitride, an inorganic nanoscale binder and a solvent. A further development can be found in the DE 10 2006 028 963 A1 respectively. WO 2007/144178 A1 , in which an abrasion-optimized non-stick coatings with passive corrosion protection is claimed. However, the coatings described have the disadvantage that they do not cure completely gas-tight under the reducing conditions of a power plant and the existing temperatures. The thus porous coatings can be infiltrated during operation of the power plant by corrosive gases, which leads to the detachment of the layer and the loss of caking protection.

The application of a gas-tight layer on metal substrates succeeds in principle by the use of a Verzunderungsschutzes based on the DE 10 2004 049 413 A1 , which relates to a method for coating metallic surfaces. The anti-scaling protection includes a silane matrix as well as aluminum pigments that solidify with increasing volume during sintering in air from as low as 300 ° C to a gas-tight and corrosion-resistant aluminum oxide layer and thus protect the pipe from corrosive attack.

Unfortunately can the described Verzunderungsschutz in a power plant for Solution of the previously described problems not used because the constituents of the coating have no non-stick properties and it can come to stick with the slag. Farther the layer is not stable at high temperatures to smoke gases up to 1100 ° C to be able to resist. A filling with ceramic Particles or nonstick materials such as boron nitride are not possible on the one hand the gas-tightness through the installation of coarse ceramic Particles is lost and on the other hand, the matrix system used (Sol-gel system) no layer thicknesses in the range of about 100 microns allowed, which would be necessary for an acceptable service life.

Of the Invention is therefore the object of a method for manufacturing to develop a corrosion-resistant, gas-tight coating, which is chemically stable to chlorine and hydrogen chloride and at the same time the adhesion of slags in incinerators avoids at high temperatures.

• • die Primerschicht keramische und/oder glasartige Partikel sowie zwischen 10 und 90 Gew.-% reaktive Bestandteile, ausgewählt aus der Gruppe bestehend aus Metallen, Halbmetallen oder Salzen, enthält, die während des Sinterns bei Temperaturen von 370 bis 1.500°C mit Gasen zu nicht flüchtigen Reaktionsprodukten reagieren, und
• • die Deckschicht temperaturstabile Feststoffe mit Hochtemperatur-Antihafteigenschaften, sowie keramische Hartstoffe und einen anorganischen oder anorganisch-organischen Binder aufweist.

This object is achieved in that a primer layer with anti-corrosion properties and then a cover layer is applied to a substrate with high temperature non-adhesive properties, wherein

• • the primer layer ceramic and / or glasarti contains particles and between 10 and 90% by weight of reactive constituents selected from the group consisting of metals, semimetals or salts, which react with gases to form non-volatile reaction products during sintering at temperatures of 370 to 1,500 ° C., and
• The cover layer has temperature-stable solids with high-temperature non-stick properties, as well as ceramic hard materials and an inorganic or inorganic-organic binder.

Surprisingly, it has now been found that a porous high-temperature stable non-stick coating, as z. B. from the EP 1 386 983 A1 or the WO 2007/144178 A1 is known to deal with a gas-tight Verzurtungsschutzlack, as he from the DE 10 2004 049 413 A1 is known, can combine. Here, the Verzonderungsschutzlack forms as a primer pipe side a gas-tight corrosion protection layer on the pipe, which prevents the attack of chlorine and hydrogen chloride in the long term, with simultaneous non-stick effect of the used as topcoat flue gas side, non-stick coating. The primer layer becomes gas-tight by reaction with the atmosphere and thus protects the substrate against scaling and corrosion.

Of the Anti-scaling (primer layer) is after drying with a boron nitride-containing nonstick coating (overcoat) overcoated, the further ceramic components to ensure the abrasion resistance contains. So a two-layer system is created, in which the primer layer in the working area tube side gas-tight and Scaled and corrosion resistant present and flue gas side overcoated with an abrasion resistant topcoat having high temperature non-stick properties becomes. The two layers thus act together synergistically.

The Primer layer has a preferred layer thickness between 5 and 30 microns dry, the topcoat a preferred layer thickness between 50 and 100 μm, which gives a maximum layer thickness for the two-layer system of approx. 55 μm-130 μm results.

The Primer layer must have excellent adhesion to the substrate exhibit. Primer layer and topcoat must be with each other have excellent adhesion and long-term stability.

A Development of the invention is that the primer layer and the cover layer are solidified after drying.

primer layer and topcoat should be simultaneously solidified after drying (Two Coat-One Fire Principle), either in the oven or on site Power plant by raising the boiler takes place.

in the Under the invention, it is provided that in the primer layer contained ceramic particles either of a semi-metal and a Non-metal or consist of a metal and a non-metal.

It is also according to the invention that the ceramic particles contained in the primer layer are selected from the group consisting of Al ₂ O ₃ , TiO ₂ , ZrO ₂ , SiO ₂ , ZnO and MgO.

It it is preferred that the ceramic contained in the primer layer Particles have a size of 2 nm to 100 μm, preferably from 10 nm to 2 μm.

It is furthermore part of the invention that in the primer layer surface-modified ceramic particles contained, preferably surface-modified with silanes or silicone resins are.

It is appropriate that in the primer layer contained reactive constituents are metals that are from the group consisting of aluminum, zinc, tin, bronze, copper, brass, magnesium, aluminum-magnesium, Aluminum-zinc, stainless steel, silver, gold, platinum, chromium, titanium, molybdenum, Nickel, iron, manganese, cerium, cobalt, zirconium, rhodium, ruthenium, Tungsten and lanthanum are selected.

A Formation of the invention is that in the primer layer contained reactive constituents are semimetals, which are from the Group consisting of silicon, boron, antimony, arsenic, phosphorus, bismuth, Germanium, polonium, selenium and tellurium are selected.

Farther it makes sense that the reactive contained in the primer layer Ingredients Salts are those selected from the group consisting of nitrates, in particular cerium nitrate, and salts of organic acids, in particular acetates, oxalates and citrates of transition metals, especially of iron, cobalt, nickel, titanium, copper, zirconium, Lanthanum and aluminum are selected.

According to the invention also provided that the reactive contained in the primer layer Constituents have a size of 2 nm to 100 μm, preferably from 10 nm to 5 μm.

It is also advantageous that contained in the primer layer ceramic and / or glassy particles and the reactive constituents in a solvent, in particular comprising water and / or Alcohol, are dispersed.

A Development of the invention is that the primer layer organic particles from the group consisting of natural Waxes, in particular paraffin wax, ester wax, acid wax, beeswax, Shellac wax, wool wax, carnauba wax, candelilla wax, rice wax, semi-synthetic waxes, especially polyethylene waxes, polypropylene waxes, Fischer-Tropsch waxes, polar synthetic waxes or amide waxes contains.

A preferred embodiment of the invention is that the solids with high-temperature non-stick properties of the cover layer are boron nitride, titanium nitride, MoS ₂ , graphite or WO ₃ .

As well it makes sense that the cover layer ceramic hard materials, in particular Boron nitride, silica, alumina, zirconia, glass frits or Contains chromium (III) oxide each alone or in combination.

A preferred embodiment of the invention is that the solids contained in the topcoat with high temperature non-stick properties, as well as the ceramic hard materials a size of 2 nm to 100 μm, preferably from 10 nm to 5 μm, exhibit.

expedient is further that the inorganic contained in the topcoat or inorganic-organic binder ceramic binders, water glasses, Glass frits, sol-gel systems or silicone resins are.

Also It is inventively provided that in constituents of the topcoat in a solvent, in particular of water and / or alcohol, dispersed or dissolved.

in the The scope of the invention is also that after the application of the primer layer and the cover layer on the substrate under a reactive Be sintered atmosphere.

In In this connection, it is provided that the reactive atmosphere Contains gases, in particular oxygen, sulfur, nitrides or chlorine, during the sintering process with the reactive components react.

in this connection it is according to the invention that the substrate Metal, glass or ceramic.

in the The invention also provides for the use of an inventive Processed coatings as non-stick coatings, as Anti-scaling layers, as corrosion protection layers, in particular against chlorine corrosion as well as abrasion or wear protection.

After all is preferred in a coating as a non-stick coating that this in power plants, in particular on power plant parts, pipes, pistons, Chimney interiors or combustion chambers, in stoves High temperature hot forming processes to prevent the growth deposits (such as alumina deposits), in the field of iron and steel, especially in the steel industry (For example, in continuous casting plants), in sewage or Exhaust air piping or in sewage or exhaust air purification systems, on machine components, in particular engine wear parts, Brake pads and is used on tools.

following the invention will be described by means of embodiments.

Example 1: Preparation of a primer layer 1 on an alcoholic basis

In 100 g of a silicone resin solution (Baysilone M 120 XB) 50 g aluminum powder MEP 027 (Mepura) with a slow running Wing stirrer dispersed in overnight. To the batch, 50 g of a 40% (wt .-%) solution of the polyacrylate Paraloid B 67 (Röhm and Haas) in p-xylene and stirred in homogeneously. To the paint mixture is 1 g of flow additive Byk 360 (Byk Chemie) added with stirring.

Of the Paint is sprayed with a compressed air spray gun (Sata, nozzle 1.4 mm) onto a steel sheet with a wet film thickness of approx. 50 μm homogeneously sprayed on. The paint film is first Pre-dried for 15 min at 200 ° C and then another 30 min at 800 ° C under air atmosphere sintered. This gives a chemical resistant ceramic primer layer.

Example 2: Preparation of a primer layer 2 on an aqueous basis

100 g of silica sol (Levasil 200/30, Bayer) are added to 100 g of glycidyloxypropyltrimethoxysilane (GPTS) and stirred at room temperature for 24 h. The resulting methanol in the hydrolysis is distilled off in vacuo at 60 ° C until the base batch is reduced to a mass of 160 g. Subsequently, 200 g of deionized water and 450 g of aluminum paste Stapa Hydrolan 2192 (Eckart) are added and stirred in homogeneously. The paint is sprayed with a compressed air spray gun (Sata, nozzle 1.4 mm) on a steel sheet with a wet film thickness of about 50 microns homogeneously sprayed. The paint film is first pre-dried for 15 min at 200 ° C and then again for 30 min at 700 ° C under Sintered air atmosphere. A chemically resistant ceramic primer layer is obtained.

Example 3: Production of the topcoat A with high temperature non-stick properties

Component A1:

• 319.25 g of an aqueous Boron nitride suspension (solids content 40% by weight)
• 79.81 g of an aqueous Cr ₂ O ₃ suspension (solids content 40% by weight, manufacturer Bayer AG)
• 79.81 g of an aqueous Al ₂ O ₃ suspension (solids content 77.8% by weight, manufacturer Alcoa)
• - 159.63 g of an aqueous zirconium oxide suspension (solids content 77.6 wt .-%, manufacturer Fa. Kynol)

Component A2:

• - 230.76 g of potassium water glass (solids content 40% by weight, betolin K28, Fa. Woellner Silicat GmbH)
• - 29.50 g of magnesium oxide powder (manufacturer Fa. CalMags GmbH)
• 100.63 g of a ground glass frit mixture in Water (solids content 50% by weight, manufacturer Fa. Ferro)
• - 0.52 g of rheology additive (xanthan gum of deuteron XL)

The Composition thus consists of the components A1 and A2, the stored separately before use. Only before the application will be the components A1 and A2 mixed. In ready mixed condition the composition is not indefinitely stable (pot life at RT: Max. 72 hours).

The both mixtures are separately in suitable containers attached by means of stirrers with dissolver disks and in each case stirred for an hour. 24 hours before applying the Coating the two components are combined. The pot life of the mixed system is a maximum of 96 h. This mixture is referred to below as cover layer A. The system can be applied by spraying.

Example 4: Preparation of the topcoat B

In a container 1.5 kg of a polysiloxane binder are presented. 0.05 kg of adjusting agent (BYK 420) are premixed in 50 g of butylglycol and then added dropwise within 15 minutes. It then follows the addition of 1.5 kg of a 40% aqueous hexagonal Of boron nitride.

Subsequently are added with stirring 0.6 kg of a 50% aqueous Added alumina suspension. It will then be 0.75 kg of a 50% aqueous suspension of a phosphate glass frit added. In the last step 500 g of a corrosion protection component 50% aqueous mixture of phosphoric acid (10 % By weight in the mixture), calcium and zinc phosphate (8% by weight and 30% by weight, respectively) and boehmite (2% by weight) added.

Finally is stirred for one hour. You get one through Spray applicable coating solution, the after firing shows excellent non-stick properties.

Example 5 Application of the Primer Topcoat System (Primer 1 and topcoat B)

Of the Paint according to Example 1 is by means of a Niederducksprühpistole as approximately 50 microns thick wet film on a previously sandblasted Pipe made of boiler steel (15Mo3) applied.

you lets the system air and coat then by means of a low-pressure spray gun the cover layer B with a wet film thickness of about 80 microns over the primer.

One such two-layer system was after drying for one hour at 500 ° C for 2 h under ambient atmosphere baked. Such a coated pipe section was then in a closed chamber for 21 days exposed to gaseous HCl and then evaluated the corrosion of the tube.

It There is no apparent corrosion occurred, with an uncoated and a pipe coated only with Topcoat B will cause severe corrosion damage had shown.

Example 6 Application of the Primer Topcoat System (Primer 2 and topcoat A)

Of the Paint according to Example 2 is using a Niederducksprühpistole as approximately 50 microns thick wet film on a previously sandblasted Pipe made of boiler steel (15Mo3) applied.

you lets the system air and coat then by means of a low-pressure spray gun the cover layer A with a wet film thickness of about 80 microns over.

One such two-layer system was at 500 ° C for Branded for 2 h under ambient atmosphere. Such a way coated pipe section was in a closed chamber 21 days exposed to gaseous HCl and then the corrosion of the pipe is assessed. It is not recognizable corrosion occurred, with one uncoated and one with topcoat only coated pipe exhibited severe corrosion damage had.

Example 7: Description of a probe experiment

One with a two-layer system according to Example 5 or 6 coated boiler tube piece was at a temperature from 430 ° C for 15 days in a waste incineration plant a strongly corrosive and caking-promoting atmosphere exposed. After exposure, the tube was examined, with the layer has remained intact and no chlorine corrosion and caking appeared. Comparative samples were heavily attacked and still had massive slag caking.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1386983 A [0004, 0004]
• DE 102006028963 A1 [0004]
• - WO 2007/144178 A1 [0004, 0009]
• DE 102004049413 A1 [0005, 0009]
• - EP 1386983 A1 [0009]

Claims (22)

A method of producing a corrosion-resistant, gas-tight coating, which comprises applying to a substrate a primer layer having anti-corrosive properties and then a cover layer having high-temperature non-stick properties, wherein the primer layer comprises ceramic and / or vitreous particles and between 10 and 90% by weight of reactive constituents , selected from the group consisting of metals, semi-metals or salts, which react with gases during sintering at temperatures of 370 to 1500 ° C to non-volatile reaction products, and • the cover layer temperature stable solids with high temperature non-stick properties, and ceramic hard materials and an inorganic or inorganic-organic binder. Process according to claim 1, characterized characterized in that the primer layer and the cover layer after be solidified simultaneously drying. Process according to claim 1, characterized characterized in that the ceramic contained in the primer layer Particles of either a semi-metal and a non-metal or consist of a metal and a non-metal. A method according to claim 1, characterized in that the ceramic particles contained in the primer layer are selected from the group consisting of Al ₂ O ₃ , TiO ₂ , ZrO ₂ , SiO ₂ , Cr ₂ O ₃ , ZnO and MgO. Process according to claim 1, characterized characterized in that the ceramic contained in the primer layer Particles have a size of 2 nm to 100 μm, preferably from 10 nm to 2 μm. Process according to claim 1, characterized characterized in that the ceramic contained in the primer layer Particle surface-modified, preferably with silanes or silicone resins are surface-modified. Process according to claim 1, characterized characterized in that the reactive contained in the primer layer Constituents are metals that are selected from the group consisting of aluminum, Zinc, tin, bronze, copper, brass, magnesium, aluminum-magnesium, Aluminum-zinc, stainless steel, silver, gold, platinum, chromium, titanium, molybdenum, Nickel, iron, manganese, cerium, cobalt, zirconium, rhodium, ruthenium, Tungsten and lanthanum are selected. Process according to claim 1, characterized characterized in that the reactive contained in the primer layer Components are semi-metals that are made up of the group Silicon, boron, antimony, arsenic, phosphorus, bismuth, germanium, polonium, selenium and tellurium are selected. Process according to claim 1, characterized characterized in that the reactive contained in the primer layer Ingredients Salts are those selected from the group consisting of nitrates, in particular cerium nitrate, and salts of organic acids, in particular acetates, oxalates and citrates of transition metals, especially of iron, cobalt, nickel, titanium, copper, zirconium, Lanthanum and aluminum are selected. Process according to claim 1, characterized characterized in that the reactive contained in the primer layer Constituents have a size of 2 nm to 100 μm, preferably from 10 nm to 5 μm. Process according to claim 1, characterized characterized in that the ceramic contained in the primer layer and / or glassy particles and the reactive components in a solvent, in particular comprising water and / or Alcohol, are dispersed. Process according to claim 1, characterized in that the primer layer comprises organic particles from the Group consisting of natural waxes, in particular Paraffin wax, ester wax, acid wax, beeswax, shellac wax, Wool wax, carnauba wax, candelilla wax, rice wax, semi-synthetic Waxing, in particular polyethylene waxes, polypropylene waxes, Fischer-Tropsch waxes, contains polar synthetic waxes or amide waxes. A method according to claim 1, characterized in that the solids with high temperature non-stick properties of the cover layer boron nitride, titanium nitride, MoS ₂ , graphite or WO ₃ are. Process according to claim 1, characterized characterized in that the cover layer ceramic hard materials, in particular Silica, alumina, zirconia, glass frit or chromium (III) oxide, respectively contains alone or in combination. Process according to claim 1, characterized characterized in that the solids contained in the topcoat with high temperature non - stick properties, as well as the ceramic Hard materials have a size of 2 nm to 100 μm, preferably from 10 nm to 5 μm. A method according to claim 1, characterized in that the inorganic or inorganic-organic Binders are ceramic binders, water glasses, glass frits, sol-gel systems or silicone resins. Process according to claim 1, characterized in that the constituents contained in the cover layer in a solvent, in particular of water and / or Alcohol, dispersed or dissolved. Process according to claim 1, characterized characterized in that after the application of the primer layer and the Cover layer on the substrate this under a reactive atmosphere be sintered. A method according to claim 18, characterized characterized in that the reactive atmosphere gases, in particular Oxygen, sulfur, nitrides or chlorine, which contains during the sintering process with the reactive ingredients react. Process according to the claims 1 to 16, characterized in that the substrate is made of metal, Glass or ceramic. Use of the according to a method according to the Claims 1 to 20 produced coatings as anti-adhesive layers, as anti-scaling coatings, as anticorrosive coatings, especially against chlorine corrosion as well as abrasion or wear protection. Use according to claim 21 as Non-stick coating, preferably in power plants, in particular on power plant parts, pipes, pistons, chimney interiors or combustion chambers, in ovens in high-temperature hot-forming processes for preventing the formation of deposits (for example of alumina deposits), in the iron and steel industry, especially in the steel industry (for example in continuous casting plants), in sewage or exhaust air piping or in sewage or exhaust air purification plants, on machine components, in particular engine wear parts, Brake pads and tools.