A coating with high Anti-corrosive effectiveness and a method for coating said coating on substrates

Abstract

The invention relates to, but is not limited to, a coating with high anti-corrosive effectiveness in severe corrosive environments and thin coating thickness for coating connecting elements used in the automotive sector, and to a method for coating the said coating on the substrate material.

Description

[0001] A COATING WITH HIGH ANTI-CORROSIVE EFFECTIVENESS AND A METHOD FOR COATING SAID COATING ON SUBSTRATES

[0002] TECHNICAL FIELD

[0003] The invention relates to, but is not limited to, a coating with high anti-corrosive effectiveness and thin coating thickness, even in severe corrosive environments, for connecting elements in the automotive sector, and to a method for coating the said coating on a substrate product.

[0004] PRIOR ART

[0005] Corrosion is the deterioration and abrasion of metals and alloys thereof as a result of chemical and electrochemical reaction with the environment. The formation of corrosion occurs spontaneously at a certain speed without the need for any external energy.

[0006] Every year, approximately 1 / 3 of the metallic materials produced in related technical fields become unusable due to corrosion. Therefore, in sectors where metals and alloys thereof are produced and used, this technical adverse situation leads to loss of capital, labor and energy. These losses amount to about 3.4% of global gross national product.

[0007] In the relevant technical field, there are a number of anti-corrosive methods to protect metals and alloys thereof against corrosion. One of the most effective methods in the fight against corrosion is the coating application.

[0008] In the automotive sector, the most widely used method to increase the corrosion life of connecting elements in particular is current and electroless electrolytic coating. Zinc and zinc-nickel coatings in particular constitute the most common coating types with this method. Coating materials can be non-metal or metal (galvanizing, zinc, zinc-nickel, lead and chromium coating, tinning). In some cases, a film providing superficial protection is applied by processes such as coating, anodic protection methods and phosphating.

[0009] In the prior art, it was found that metals and alloys thereof could not be effectively protected against corrosion with the application of conventional methods and were corroded in severe corrosive ambient conditions containing ammonium nitrate, urea, potassium, diammonium phosphate, agricultural lime, ammonium thiosulfate, sodium chlorate, nitrate, ammonia, nitrogen <28%, and atrazine.

[0010] In order to increase the anti-corrosive properties of metals and alloys thereof, the thickness of the anti-corrosive coatings on the surface is increased to obtain higher corrosion resistance against aggressive chemicals and corrosive environments compared to the known coatings; however, especially in the automotive sector, it is not preferable to have too thick coatings since a high coating thickness will increase the volume of the connecting element coated, which may adversely affect the proper assembly of the connecting element. For this reason, a coating thickness in the range of a few microns is generally preferred as the coating thickness in the technical specifications.

[0011] As a result, there is a need to develop coatings with high anti-corrosive effectiveness and thin coating thicknesses, even in severe corrosive ambient conditions, in order to offer solutions and advantages to the needs in the relevant technical fields.

[0012] SUMMARY OF THE INVENTION

[0013] The invention relates to a coating which overcomes the above-mentioned disadvantages, by increasing the anti-corrosive effectiveness of particularly metals or metal alloys exposed to severe corrosive environments.

[0014] In another aspect, the invention provides a coating with thin coating thicknesses for improving the corrosion resistance of metals or metal alloys.

[0015] In another aspect, the invention relates to a method for coating substrates with a coating with high anti-corrosive effectiveness.

[0016] DETAILED DESCRIPTION OF THE INVENTION

[0017] In this detailed description, the subject matter of the invention relates to a coating developed for substrates made of metals or metal alloys, which provides an anticorrosive effect even against severe corrosive environments and has thin coating thicknesses, and is described by way of non-limiting examples solely for a better understanding of the subject matter.

[0018] In the invention, the phrase “corrosion” means the degradation of metals, metal alloys and similar substrates by certain mechanisms in ambient conditions. Moreover, the phrase “corrosion” in the invention can also refer to much more severe corrosive environments. Within the scope of the invention, severe corrosive environments may mean environments containing ammonium nitrate, urea, potassium, diammonium phosphate, agricultural lime, ammonium thiosulfate, sodium chlorate, nitrate, ammonia, nitrogen <28%, and atrazine. In the art, anti-corrosive coatings for corrosive environments are available; however, it has been found that existing technical solutions are not particularly sufficient for connecting elements in the severe corrosive environments mentioned here. The present inventors offer technical solutions and advantages to the relevant technical field, in particular for connecting elements, to provide a high anti-corrosive effect in severe corrosive environments. Although it is stated herein that the technical solutions and advantages realized are for connecting elements used in the automotive sector in order to further clarify the invention, the scope of protection of the invention is not limited thereto. The technical solutions and advantages described in the invention can also be used in products, apparatus or elements other than connecting elements.

[0019] In the invention, the phrase “substrate material” means products that are intended to be protected from corrosive environments and are expected to have mechanical strength and other assembly properties for the technical field in which they are used. In the invention, the substrate material is selected from the group consisting of metals and metal alloys, non-metals and non-metal alloys, polymers or composite materials. In a preferred embodiment, the substrate material is a metal or metal alloy material selected from the group consisting of nickel, zinc, chromium, aluminum, vanadium, manganese, titanium, magnesium, tin, copper, iron, silicon, molybdenum or an alloy thereof. In a most preferred embodiment, the substrate material can be a connecting element or sheet metal, preferably made of metal or metal alloy. The scope of protection of the invention is not limited by the nature of the substrate.

[0020] The invention relates to a coating with an anti-corrosive effect to overcome technical disadvantages in the relevant technical field and to provide new technical solutions. The coating according to the invention is essentially a hybrid coating. In a preferred embodiment of the invention, the coating according to the invention comprises more than one layer and these layers show a synergistic effect when they are present together.

[0021] Within the scope of the invention, the phrase “hybrid coating” is used to refer to a coating in which a synergistic effect is achieved to exhibit anti-corrosive effectiveness by using separate layers with different technical effects together. The coating according to the invention is preferably a hybrid coating consisting of at least two layers.

[0022] In an embodiment of the invention, the coating according to the invention may be coated directly onto the substrate material. In an embodiment of the invention, the substrate material described above may be coated with a coating of any metal or metal alloy material, for example a coating containing zinc, such as zinc, zinc-nickel or zincphosphate, and the coating according to the invention may be applied on the substrate material coated with the said metal coatings. A coating containing zinc, such as zinc, zinc-nickel or zinc-phosphate, which is applied to the substrate material prior to coating with the coating according to the invention, may preferably be applied to the substrate material by electrolytic coating.

[0023] Within the scope of the invention, “electrolytic coating” refers to a coating realized by forming a thin film layer on the surface of the substrate material by the electrolysis method.

[0024] Within the scope of the invention, “electrolysis” refers to the chemical changes that occur in the parts of the electrodes immersed in the liquid with the help of electrolytic conductivity by passing an electric current between two metal electrodes immersed in a salt solution or a molten salt with the help of a current source.

[0025] The coating according to the invention preferably comprises at least two layers. Each of these layers provides a technical solution to the final product.

[0026] Preferably, the coating according to the invention comprises three layers, namely a bottom, a middle and a top layer. In the preferred embodiment of the invention, the coating comprises at least one bottom layer comprising chromium or a chromium-based compound, at least one middle layer comprising phosphorus or a phosphorus-based compound and at least one top layer comprising a polymeric material.

[0027] In a preferred embodiment of the invention, the bottom and middle layers forming the coating are coated on the substrates by the electrolytic coating method. In the present invention, chemical baths are prepared for the bottom and middle layers for performing electrolytic coating processes. The substrate materials are placed in the said prepared chemical baths and subjected to coating processes.

[0028] The coating according to the invention comprises at least one bottom layer in contact with the substrate material surfaces and covering at least part of the bottom and / or lateral surfaces of the substrate materials. In the coating according to the invention, the chemical bath prepared for coating the bottom layer on the substrate surface comprises at least one chromium or chromium-based compound and at least one corrosion. In the preparation of the chemical bath for coating the bottom layer on the substrate, water is preferably used in addition to the said chemical materials.

[0029] The said bottom layer comprises at least one chromium or chromium-based compound as the main component. The bottom layer of the coating according to the invention comprises chromium or the chromium-based compound in order to delay rusting of the substrate and thereby increase its lifetime. The bottom layer of the coating according to the invention comprises at least one chromium-based compound selected from the group consisting of chromic acid, chromium sulfate [Cr2(SC>4)2], chromium alum [KCr(SC>4)2], chromium chloride [CrC ], chromium bromide [CrBrs], chromium fluoride [CrFs], chromium (III) nitrate [CrNOs] compounds or any mixture thereof in certain ratios. In the most preferred embodiment, the bottom layer comprises at least one of chromium (III) nitrate [CrNOs] and / or chromium sulfate [Cr2(SC>4)2] compounds as a chromium-based compound.

[0030] The bottom layer comprises at least one corrosion inhibitor, if preferred. In the invention, the bottom layer comprises at least one compound selected from a group consisting of nitrate, sulfate and / or halogen salts as a corrosion inhibitor. In a preferred embodiment of the invention, the bottom layer comprises at least one compound selected from a group consisting of cobalt-based nitrate, sulfate and / or halogen salts as a corrosion inhibitor. In a preferred embodiment of the invention, the bottom layer comprises at least one of cobalt sulfate and / or cobalt nitrate compounds as a corrosion inhibitor.

[0031] The coating according to the invention comprises at least one middle layer. In a preferred embodiment, the middle layer is located in contact with and in the upper vicinity of the bottom layer of the coating.

[0032] The chemical bath prepared for coating the middle layer of the coating according to the invention on the substrate surface comprises at least one phosphorus or phosphorus- based compound, at least one corrosion inhibitor as chemical material. In the preparation of the chemical bath for coating the middle layer on the substrate, water is preferably used in addition to the said chemical materials.

[0033] The middle layer of the coating according to the invention comprises at least one phosphorus or phosphorus-based compound. Preferably, phosphorus or a phosphorus- based compound herein provides phosphorus ions for the middle layer when dissolved in a suitable solvent, e.g. water. The middle layer comprises at least one of dihydrogen phosphate [H2PO4]", ammonium dihydrogen phosphate [(NH4)(H2PO4)], monocalcium phosphate (Ca(H2PC>4)2) compounds or any mixture thereof in certain ratios as phosphorus-based compound.

[0034] The middle layer forms a tight bond with the bottom and top layers due to the strong bonding properties of the phosphate it contains. Through this strong interaction, the middle layer prevents the passage of corrosive substances and contributes to increasing the anti-corrosive effect of the coating. The phosphate contained in the middle layer of the coating according to the invention is preferably fine-grained and forms a more compact structure, preventing the interaction of the substrate with the atmosphere and contributing to the minimization of oxygen-induced rust formation.

[0035] The middle layer preferably comprises at least one corrosion inhibitor. The middle layer comprises at least one from a group consisting of nitrate, sulfate and / or halogen salts or any mixture thereof in certain ratios as a corrosion inhibitor. In a preferred embodiment of the invention, the middle layer comprises at least one of calcium-based nitrate, sulfate and / or halogen salts or any mixture thereof in certain ratios as a corrosion inhibitor. In another preferred embodiment of the invention, the middle layer comprises at least one of calcium sulfate, calcium nitrate and / or cobalt nitrate compounds as a corrosion inhibitor.

[0036] The coating according to the invention comprises at least one top layer. In a preferred embodiment of the invention, the top layer is located in contact with and in the upper vicinity of the middle layer of the coating according to the invention

[0037] A chemical mixture comprising a polymeric material is prepared for coating the top layer of the coating according to the invention on the substrate surface. The said chemical mixture comprises at least one polymeric material and / or at least one anti-corrosive additive.

[0038] In a preferred embodiment of the invention, the top layer of the coating according to the invention is applied to the substrate materials as at least one layer, preferably two layers, by the dip-spin or spraying method. Accordingly, the substrate materials are immersed in tanks with the polymeric material-based chemical mixture contained in the top layer and after removal from the tanks, centrifugation is applied to ensure homogeneous distribution of the top layer on the surface of the substrate material.

[0039] The top layer of the coating according to the invention comprises at least one polymeric material. The polymeric material in the top layer creates an anti-corrosive barrier for the substrate and preferably for the coating components thereon and also creates mechanical resistance to impact and abrasion. The top layer comprises at least one polymeric material selected from the group consisting of polymers obtained from polyhydroxyethylmethacrylate, 2-methoxyl-1 -methylethyl acetate, 1 -methoxy 2-acetoxy propane, 1 -methoxy 2-propyl acetate, 1 -methoxy-2-propanol acetate, 1 -methoxylpropyl acetate, 2-acetoxy- 1 -methoxypropane, 2-propanol, 1 -methoxy acetate, Dowanol PMA glycol ether acetate, methoxy propyl acetate, propylene glycol methyl ether acetate, propylene glycol monomethyl ether acetate monomers and / or PGMEA, PGMA polymers or any mixture thereof in certain ratios as the polymeric material. In a preferred aspect of the invention, the said top layer comprises a polymeric material obtained from 2- methoxyl-1 -methylethyl acetate monomer as the polymeric material. The polymeric material contained in the top layer of the coating according to the invention forms a composite material with the anti-corrosive additive, if preferred. In the present invention, the top layer comprises at least one of trizinc bis(orthophosphate), zinc orthophosphate, trizinc phosphate, zinc phosphate and trizinc diphosphate, NasSC , K2CO3, CaCOs, MgO, AI2O3, SiC>2, BN, TiC>2 compounds or any mixture thereof in certain ratios as the anti-corrosive additive. In the top layer of the coating according to the invention, the said polymer-based composite material comprising the polymeric material and the anti-corrosive additive acts as an excellent protective barrier against hydrogen and oxygen as well as moisture and other gases. In addition, the said polymer-based composite material also provides insulating properties to the top layer, contributing to the prevention of galvanic corrosion caused by rusting due to the electron transfer between two different materials of metal or metal alloys by preventing electron exchange.

[0040] In a further aspect, the invention relates to a method for coating the characterized coating on substrate materials. Each layer is coated on substrate materials by applying separate technical processes. The processes applied to coat each coating on the substrate surface are described in detail below.

[0041] Coating the bottom layer on the substrate materials

[0042] In a preferred embodiment of the invention, the bottom layer is coated on the substrate materials by electrolyte coating or alternatively by the electroless coating method. For the application of the said bottom layer to the substrates, a chemical bath comprising the following chemical material mixture and a diluent is prepared.

[0043] The electroless coating method used for coating the bottom layer of the coating according to the invention on the substrate surface is the technique of coating ions obtained by autocatalytic chemical reduction method on substrate surfaces made of metal, ceramic or polymer without using electric current.

[0044] In the preferred embodiment, the temperature of the chemical bath prepared for the bottom layer is a value between 30 °C to 35 °C. In order to coat the bottom layer on the substrate materials, the substrate material is kept in the prepared chemical bath for at least 30 seconds. The chemical bath prepared for coating the bottom layer of the coating according to the invention on the substrate surface comprises at least one chromium or chromium-based compound, at least one corrosion inhibitor and at least one electrolyte anodizing material as chemical material. In the preparation of the chemical bath for coating the bottom layer on the substrates, water is preferably used as a diluent in addition to the said chemical materials.

[0045] The coating according to the invention comprises at least one bottom layer in contact with the substrate material surfaces and covering at least part of the bottom and / or lateral surfaces of the substrate material. The said bottom layer comprises chromium or a chromium-based compound as the main component. The bottom layer of the coating according to the invention comprises chromium or a chromium-based compound to provide an anti-rust function in order to delay rusting of the substrate and thereby increase its lifetime.

[0046] The chemical bath prepared for the bottom layer of the coating according to the invention preferably comprises at least one chromium or chromium-based compound. In the invention, the chemical bath prepared for the bottom layer comprises chromic acid, chromium sulfate [Cr2(SO4)2], chromium alum [KCr(SO4)2], chromium chloride [CrCh], chromium bromide [CrBrs], chromium fluoride [CrFs], chromium (III) nitrate [CrNOs] compounds or any mixture thereof in certain ratios as the chromium-based compound. In the most preferred embodiment, the chemical bath prepared for the bottom layer comprises at least one of chromium (III) nitrate [CrNOs] and / or chromium sulfate [Cr2(SO4)2] compounds as the chromium-based compound. The chemical bath prepared for coating the bottom layer of the coating according to the invention on the substrate surface comprises at least one chromium or chromium-based compound in the range of 5% to 40%, preferably 7% to 35%, more preferably 10% to 30% of the total weight of the chemical material contained therein.

[0047] The chemical bath prepared for the bottom layer comprises at least one corrosion inhibitor, if preferred. In the invention, the chemical bath prepared for the bottom layer comprises at least one compound selected from a group consisting of nitrate, sulfate and / or halogen salts as the corrosion inhibitor. In a preferred embodiment of the invention, the chemical bath prepared for the bottom layer comprises at least one compound selected from a group consisting of cobalt-based nitrate, sulfate and / or halogen salts as the corrosion inhibitor. In a preferred embodiment of the invention, the chemical bath prepared for the bottom layer comprises at least one of cobalt sulfate and / or cobalt nitrate compounds as the corrosion inhibitor. The chemical bath prepared for coating the bottom layer of the coating according to the invention on the substrate surface comprises at least one corrosion inhibitor in the range of 1% to 20%, preferably 2% to 15%, more preferably 2.5% to 10% of the total weight of the chemical material contained therein.

[0048] The chemical bath prepared for the bottom layer of the coating according to the invention preferably comprises at least one electrolyte anodizing material. In a preferred embodiment of the invention, the chemical bath prepared for the bottom layer comprises at least one of methanoic acid [HCOOH], ethanoic acid [CH3COOH], propanoic acid [CH3CH2COOH], butanoic acid [CH3(CH2)2COOH], pentanoic acid [CH3(CH2)3COOH], hexanoic acid [CH3(CH2)4COOH], heptanoic acid [CH3(CH2)5COOH], octanoic acid [CH3(CH2)6COOH], nonanoic acid [CH3(CH2)7COOH], decanoic acid [CH3(CH2)8COOH], dodecanoic acid [CH3(CH2)I0COOH], tetradecanoic acid [CH3(CH2)I2COOH], hexadecanoic acid [CH3(CH2)I4COOH], octadecanoic acid [CH3(CH2)I6COOH], eicosanoic acid [CH3(CH2)I8COOH] compounds or mixture thereof in certain ratios as the electrolyte anodizing material. The chemical bath prepared for coating the bottom layer of the coating according to the invention on the substrate surface comprises the electrolyte anodizing material in the range of 1% to 20%, preferably 2% to 15%, more preferably 5% to 10% of the total weight of the chemical material contained therein.

[0049] In a most preferred embodiment, the chemical bath prepared for coating the bottom layer on the substrate surface comprises the chromium or chromium-based compound at a value in the range of 10% to 30%, the electrolyte anodizing material at a value in the range of 5% to 10%, and the corrosion inhibitor at a value in the range of 2.5% to 10% of the total weight of the chemical material contained therein.

[0050] Coating the middle layer on the substrate materials so as to be positioned in the upper vicinity of the bottom layer

[0051] In a preferred embodiment of the invention, the middle layer is coated on the substrate materials by electrolyte coating or alternatively by the electroless coating method. In order to apply the said coating method, a chemical bath comprising the chemical material mixture stated below for the middle layer and a diluent is prepared and the coating process of the middle layer is carried out for a period between 10 and 15 minutes with a bath temperature at a temperature value between 55 °C and 80 °C.

[0052] The electroless coating method also used for coating the middle layer on the substrate surface as in the bottom layer of the coating according to the invention is the technique of coating ions obtained by autocatalytic chemical reduction method on substrate surfaces made of metal, ceramic or polymer without using electric current.

[0053] The chemical bath prepared for coating the middle layer of the coating according to the invention on the substrate surface comprises at least one phosphorus or phosphorus providing compound, at least one corrosion inhibitor, at least one electrolyte salt, and at least one conductive agent as the chemical material. In the preparation of the chemical bath for coating the middle layer on the substrate, water is preferably used as a diluent in addition to the said chemical materials.

[0054] The chemical bath prepared for the middle layer of the coating according to the invention comprises at least one phosphorus or phosphorus-based compound. Preferably, the phosphorus providing compound herein provides phosphorus ions for the middle layer when dissolved in a suitable solvent, e.g. water. In a preferred embodiment of the invention, the chemical bath prepared for the middle layer comprises at least one of dihydrogen phosphate [H2PO4]", ammonium dihydrogen phosphate [(NH4)(H2PO4)], monocalcium phosphate (Ca(H2PC>4)2) compounds or any mixture thereof in certain ratios as the phosphorus-based compound. The chemical bath prepared for coating the middle layer of the coating according to the invention on the substrate surface comprises at least one phosphate providing compound in the range of 5% to 75%, preferably 8% to 60%, more preferably 10% to 50% of the total weight of the chemical material contained therein.

[0055] The chemical bath prepared for the middle layer preferably comprises at least one corrosion inhibitor. The chemical bath prepared for the middle layer comprises at least one compound selected from a group consisting of nitrate, sulfate and / or halogen salts as the corrosion inhibitor. In a preferred embodiment of the invention, the chemical bath prepared for the middle layer comprises at least one of calcium-based nitrate, sulfate and / or halogen salts or any mixture thereof in certain ratios as a corrosion inhibitor. In another preferred embodiment of the invention, the chemical bath prepared for the middle layer comprises at least one of calcium sulfate, calcium nitrate and / or cobalt nitrate compounds as a corrosion inhibitor. The chemical bath prepared for coating the middle layer of the coating according to the invention on the substrate surface comprises at least one corrosion inhibitor in the range of 5% to 35%, preferably 8% to 30%, more preferably 10% to 25% of the total weight of the chemical material contained therein.

[0056] In the invention, the chemical bath prepared for the middle layer comprises at least one electrolyte salt. The chemical bath prepared for the middle layer preferably uses zinc- based compounds as the electrolyte salt. The chemical bath prepared for the said middle layer comprises at least one of zinc nitrate, zinc chlorate, zinc sulfate, zinc phosphate, zinc molybdate, zinc chromate, zinc ricinoleate compounds or any mixture thereof in certain ratios as the electrolyte salt. The chemical bath prepared for coating the middle layer of the coating according to the invention on the substrate surface comprises at least one electrolyte salt in the range of 2.5% to 10% of the total weight of the chemical material contained therein.

[0057] The chemical bath prepared for the middle layer comprises at least one conductive agent. The chemical bath prepared for the middle layer comprises at least one of 3- (benzthiazoyl-2-thio)-propylsulfonic acid sodium salt, 3-mercaptopropane-1 -sulfonic acid sodium salt, ethylenedithiodipropylsulfonic acid sodium salt, disulfide disodium salt, bis(w-sulfobutyl)-disulfide disodium salt, bis-(w-sulfohydroxypropyl)-disulfide disodium salt, bis(w-sulfopropyl)-disulfide disodium salt, bis-(w-sulfopropyl)-sulfide disodium salt, methyl-(w-sulfopropyl) sodium salt, methyl-(w-sulfopropyl)-trisulfide disodium salt, O- ethyl-dithiocarbonic acid-S-(w-sulfopropyl)-ester, thiophosphoric acid-O-ethyl-bis((w- sulfopropyl)-ester disodium salt, thiophosphoric acid-tri(w-sulfopropyl)-ester trisodium salt, N,N-dimethyldithiocarbamic acid (3-sulfopropyl) ester sodium salt, 3-(2- benzthiazolylthio)-1 -propanesulfonic acid sodium salt or any mixture thereof in certain rations as the conductive agent. The chemical bath prepared for coating the middle layer of the coating according to the invention on the substrate surface comprises at least one conductive agent in the range of 2.5% to 10% of the total weight of the chemical material contained therein.

[0058] The chemical bath prepared for the middle layer comprises a second electrolyte salt, if preferred. The chemical bath prepared for the middle layer comprises at least one of orthophosphoric acid, oligophosphoric acids, polyphosphoric acids, cyclo- or metaphosphoric acids, branched polyphosphates, paraphosphoric acid, thiophosphoric acid, perphosphoric acid, superphosphoric acid, hyperphosphoric acid or any mixture thereof in certain ratios as the second electrolyte salt. In case the middle layer of the coating according to the invention preferably comprises a second electrolyte salt, the chemical bath prepared for coating the middle layer on the substrate surface comprises a second electrolyte salt in the range of 2.5% to 5% of the total weight of the chemical material contained therein.

[0059] In a most preferred embodiment, the chemical bath prepared for coating the middle layer on the substrate surface comprises phosphorus or a phosphorus-based compound at a value in the range of 10% to 50% of the total weight of the chemical material contained therein, an electrolyte salt at a value in the range of 2.5% to 10% by weight thereof, preferably a second electrolyte salt at a value in the range of 2.5% to 5% by weight thereof, a corrosion inhibitor at a value in the range of 10% to 25% by weight thereof and a conductive agent at a value between 2.5% and 10% thereof.

[0060] Coating the top layer on the substrate materials so as to be positioned in the upper vicinity of the middle layer

[0061] In a preferred embodiment of the invention, the top layer of the coating according to the invention is applied to the substrate materials as at least one layer, preferably two layers, by the dip-spin or spraying method. Accordingly, the substrate materials are immersed in tanks with the polymeric material-based chemical mixture contained in the top layer and after removal from the tanks, centrifugation is applied to ensure homogeneous distribution of the top layer on the surface of the substrate material. The coating processes are carried out over a period between 90 and 270 minutes. Herein, the temperature of the chemical mixture is at a temperature value between 20 °C to 45 °C.

[0062] In the next process step, the substrate material coated with the top layer is subjected to a curing process at a temperature value between 70 to 80 °C for a period between 10 to 15 minutes. In a preferred embodiment of the invention, the top layer is applied to the substrate materials twice successively. When applying for the second time, the above processes are repeated. A chemical mixture comprising a polymeric material is prepared for coating the top layer of the coating according to the invention on the substrate surface. The said chemical mixture comprises at least one polymeric material, at least one anti-corrosive additive, and at least one diluent.

[0063] The chemical mixture prepared for the top layer of the coating according to the invention comprises at least one polymeric material. The polymeric material matrix component in the chemical mixture prepared for the top layer forms a composite with an anti-corrosive additive as a reinforcing component, forming an anti-corrosive barrier and also contributing to the impact and abrasion resistance of the substrate. The chemical mixture prepared for the top layer comprises at least one polymeric material selected from the group consisting of polymers obtained from polyhydroxyethylmethacrylate, 2-methoxyl- 1 -methylethyl acetate, 1 -methoxy 2-acetoxy propane, 1 -methoxy 2-propyl acetate, 1 - methoxy-2-propanol acetate, 1 -methoxy-2-propyl acetate, 2-acetoxy-1 - methoxypropane, 2-propanol, 1 -methoxy acetate, Dowanol PMA glycol ether acetate, methoxy propyl acetate, propylene glycol methyl ether acetate, propylene glycol monomethyl ether acetate monomers and PGMEA, PGMA polymers or any mixture thereof in certain ratios as the polymeric material. In a preferred embodiment of the invention, the chemical mixture prepared for the top layer comprises a polymeric material obtained from the 2-methoxyl-1 -methylethyl acetate monomer as the polymeric material. The chemical mixture prepared for coating the top layer of the coating according to the invention on the substrate surface comprises at least one polymeric material in the range of 30% to 85%, preferably 40% to 75%, more preferably 50% to 70% of the total weight thereof.

[0064] The chemical mixture prepared for the top layer comprises at least one anti-corrosive additive. The chemical mixture prepared for the top layer comprises at least one of trizinc bis(orthophosphate), zinc orthophosphate, trizinc phosphate, zinc phosphate and trizinc diphosphate, NasSOzi, K2CO3, CaCOs, MgO, AI2O3, SiO2, BN, Ti©2 compounds or any mixture thereof in certain ratios as the anti-corrosive additive. In a preferred embodiment of the invention, the chemical mixture prepared for the top layer comprises trizinc bis(orthophosphate) as the anti-corrosive additive. The chemical mixture prepared for coating the top layer of the coating according to the invention on the substrate surface comprises at least one anti-corrosive additive in the range of 2% to 20%, preferably 4% to 15%, more preferably 5% to 10% of the total weight thereof. The chemical mixture prepared for the top layer comprises at least one diluent. The said diluent in the chemical mixture prepared for the top layer is added to determine the fluidity of the chemical mixture and to perform the function of preventing early polymerization processes. The top layer of the coating according to the invention comprises a diluent of between 5% to 10% of the total weight of the chemical mixture prepared for coating the top layer on the substrate surface. The said chemical mixture comprises at least one diluent selected from the group consisting of ethane, propane, butane, n-alkanes such as normal- and isopentane, cycloalkanes such as cyclopentane and cyclohexane, gas plant condensates (n-alkanes, naphthenes, aromatics, etc.) or any mixture thereof in certain ratios as the diluent.

[0065] The chemical mixture prepared for the top layer comprises at least one second diluent, if preferred. The chemical mixture prepared for the top layer preferably comprises butanol as the second diluent. The second diluent in the chemical mixture is also included to provide the functions of determining the fluidity of the chemical mixture and preventing early polymerization processes. The chemical mixture prepared for coating the top layer of the coating according to the invention on the substrate surface comprises a second diluent of between 5% and 10% of the total weight thereof.

[0066] The chemical mixture prepared for the top layer comprises a third diluent, if preferred. The said chemical mixture preferably comprises at least one third diluent selected from the group consisting of 1 -Cyclohexanol, cyclohexyl alcohol, hexahydrophenol, hydroxycyclohexane, hexaline or any mixture thereof in certain ratios as the third diluent. The chemical mixture prepared for coating the top layer of the coating according to the invention on the substrate surface comprises a third diluent of between 5% and 10% of the total weight thereof.

[0067] Each of the layers within the coating according to the invention provides technical solutions and advantages to the final product in order to realize the objects of the invention mentioned above. The coating having a hybrid structure in this way particularly shows high anti-corrosive effects even in aggressive corrosive environments due to the layers contained therein. In order to determine the anti-corrosive effectiveness of the coating according to the invention, the anti-corrosive effectiveness of a sample coating according to the invention, for which the contents of the chemical baths used for coating the bottom, middle and top layers are given in Table 1 , was assayed in tests in accordance with DIN EN ISO 4628- 5 standards. The results of the test performed according to the DIN EN ISO 4628-5 standard on M10 and M20 substrate material coated with a sample coating according to the said invention are given in Table 2.

[0068] “M10” and “M20” refer to the dimensions of the substrate material (connecting element) and “M” refers to the major thread diameter and the unit is millimeter. The major thread diameters for the M10 and M20 substrate materials (connecting elements) used in the tests are 10 and 20 millimeters respectively.

[0069] The column entitled “ISO 4628-5 Classification” in T able 2 indicates the degree of rusting of the tested substrate material coated with the sample coating according to the invention when exposed to the relevant corrosive substances. According to the ISO 4628-5 standard, a range of 0-5 is given as the degree of rusting and grading is made in the range of 0-5 according to the size of the detected rust. For example, if the rust evaluated under a microscope is magnified 10 times (1 Ox) and there is no visible rust, the degree of rust is classified as 0. According to Table 2, the substrate material coated with the sample coating according to the invention, which was tested according to DIN EN ISO 4628-5 standard, the content of which is given in Table 1 , was classified as 0 since no rust formation was observed.

[0070] In addition, the substrate material coated with the sample coating according to the invention, for which the contents of the chemical baths used for coating the bottom, middle and top layer are given in Table 1 , was also subjected to Drop tests and it was found that the said coating showed high anti-corrosive effectiveness.

[0071] In Table 1 , the contents of the chemical baths used for coating the bottom, middle and top layers of a sample coating within the scope of the coating according to the invention are given. The said coating was coated on M10 and M20 substrate material using the methods described in detail above regarding the application of the bottom layer, the middle layer and the top layer, and then tests were carried out to determine the anticorrosive effectiveness. The contents described in Table 1 for the bottom layer and middle layer are the contents of the chemical baths used for coating the bottom and middle layers, and the chemical bath prepared for coating the said bottom and middle layers on the substrate preferably uses water in addition to the chemical materials. However, as a top layer, a mixture of chemical materials comprising polymeric material is applied and the full content of this mixture of chemical materials is shared in Table 1 .

[0072] Table 1 . Chemical content of the coating according to the invention. Table 2. Test results and qualitative evaluations with DIN EN ISO 4628-5 standards in various severe corrosion environments of the product obtained by coating M10 and M20 substrates with the coating material according to the invention, for which the contents of the chemical baths used for coating the bottom, middle and top layers are given in Table 1.

[0073] In the tests carried out, it has been observed that the coating according to the invention shows high anti-corrosive effectiveness even at low thicknesses. Accordingly, the coating according to the invention is able to provide the expected high anti-corrosive effectiveness even at coating ranges of between 5 to 15 microns preferred in the present art.

[0074] The scope of protection of the invention is set out in the appended claims and shall in no way be limited to what is described in this detailed description for illustrative purposes. Indeed, it is clear that a person skilled in the art can come up with similar embodiments in light of the foregoing description without departing from the main theme of the invention.

Claims

CLAIMS1 . A coating for providing anti-corrosive effectiveness for a substrate material, and comprising the following components- at least one bottom layer comprising at least one chromium or chromium- based compound,- at least one middle layer comprising at least one phosphorus or phosphorus-based compound,- at least one top layer containing at least one polymeric material.

2. A coating according to claim 1 , characterized in that the bottom layer comprises at least one chromium-based compound selected from the group consisting of chromic acid, chromium sulfate, chromium alum, chromium chloride, chromium bromide, chromium fluoride, chromium nitrate.

3. A coating according to claim 2, characterized in that the bottom layer comprises at least one of chromium (III) nitrate [CrNOs] and / or chromium sulfate [C^SC ] compounds as the chromium-based compound.

4. A coating according to any one of the preceding claims, characterized in that the bottom layer comprises at least one corrosion inhibitor selected from the group consisting of nitrate, sulfate and / or halogen salts.

5. A coating according to claim 4, characterized in that the bottom layer comprises at least one of cobalt sulfate and / or cobalt nitrate compounds as the corrosion inhibitor.

6. A coating according to any one of the preceding claims, characterized in that the middle layer comprises at least one of dihydrogen phosphate, ammonium dihydrogen phosphate, monocalcium phosphate compounds as the phosphorus- based compound.

7. A coating according to any one of the preceding claims, characterized in that the middle layer comprises at least one of nitrate, sulfate and / or halogen salts as the corrosion inhibitor.

8. A coating according to claim 7, characterized in that the middle layer comprises at least one of calcium sulfate, calcium nitrate and / or cobalt nitrate compounds as the corrosion inhibitor.

9. A coating according to any one of the preceding claims, characterized in that the top layer comprises at least one polymeric material selected from a group consisting of polymers obtained from polyhydroxyethylmethacrylate, 2-methoxyl- 1 -methylethyl acetate, 1 -methoxy 2-acetoxy propane, 1 -methoxy 2-propyl acetate, 1 -methoxy-2-propanol acetate, 1 -methoxy-2-propyl acetate, 2-acetoxy- 1 -methoxypropane, 2-propanol, 1 -methoxy acetate Dowanol PMA glycol ether acetate, methoxy propyl acetate, propylene glycol methyl ether acetate, propylene glycol monomethyl ether acetate monomers, PGMEA, PGMA polymers or a mixture thereof.

10. A coating according to claim 9, characterized in that the top layer comprises a polymeric material obtained from 2-methoxyl-1 -methylethyl acetate monomer as the polymeric material.11 . A coating according to any one of the preceding claims, characterized in that the top layer comprises a composite material comprising a polymeric material and an anti-corrosive additive as components.

12. A coating according to claim 11 , characterized in that the top layer comprises at least one of trizinc bis(orthophosphate), zinc orthophosphate, trizinc phosphate, zinc phosphate and trizinc diphosphate, NasSOzi, K2CO3, CaCOs, MgO, AI2O3, SiO2,BN, TiO2 compounds as the anti-corrosive additive.

13. A method for coating a substrate material with a coating according to any one of the preceding claims, characterized in that it comprises the process steps of:- preparing a chemical bath comprising at least one chromium or chromium-based compound for coating on the substrate material as the bottom layer thereof, coating the bottom layer on the substrate material by electrolysis method or electroless coating method in the said prepared chemical bath,- preparing a chemical bath comprising at least one phosphorus or phosphorus-based compound for coating the middle layer on the substrate material,- coating the middle layer in the upper vicinity of the bottom layer by electrolysis method or electroless coating method in the said prepared chemical bath,- preparing a chemical mixture comprising at least one polymeric material for coating the top layer on the substrate material,- coating the top layer on the substrate material in the upper vicinity of the middle layer by dip-spin or spraying method in the said chemical mixture.

14. A method according to claim 13, characterized in that the substrate material is kept for at least 30 seconds in the chemical bath prepared for the bottom layer and having a temperature at a value between 30 °C to 35 °C.

15. A method according to any one of claims 13-14, characterized in that the chemical bath prepared for the bottom layer comprises at least one selected from the group consisting of chromic acid, chromium sulfate, chromium alum, chromium chloride, chromium bromide, chromium fluoride, chromium nitrate compounds as the chromium-based compound.

16. A method according to any one of claims 13-15, characterized in that the chemical bath prepared for coating the bottom layer on the substrate surface comprises at least one chromium or chromium-based compound at a value in the range of 5% to 40% of the total weight of the chemical material contained therein.

17. A method according to claim 16, characterized in that the chemical bath prepared for coating the bottom layer on the substrate surface comprises at least one chromium-based compound at a value in the range of 7% to 35% of the total weight of the chemical material contained therein.

18. A method according to claim 17, characterized in that the chemical bath prepared for coating the bottom layer on the substrate surface comprises at least one chromium-based compound at a value in the range of 10% to 30% of the total weight of the chemical material contained therein.

19. A method according to any one of claims 13-18, characterized in that the chemical bath prepared for coating the bottom layer on the substrate surface comprises at least one corrosion inhibitor and at least one electrolyte anodizing material in addition to at least one chromium or chromium-based compound.

20. A method according to claim 19, characterized in that the said chemical bath comprises at least one of methanoic acid [HCOOH], ethanoic acid [CH3COOH], propanoic acid [CH3CH2COOH], butanoic acid [CH3(CH2)2COOH], pentanoic acid [CH3(CH2)3COOH], hexanoic acid [CH3(CH2)4COOH], heptanoic acid[CH3(CH2)5COOH], octanoic acid [CH3(CH2)6COOH], nonanoic acid[CH3(CH2)7COOH], decanoic acid [CH3(CH2)8COOH], dodecanoic acid[CH3(CH2)I0COOH], tetradecanoic acid [CH3(CH2)I2COOH], hexadecanoic acid [CH3(CH2)I4COOH], octadecanoic acid [CH3(CH2)I6COOH], eicosanoic acid [CH3(CH2)I8COOH] as the electrolyte anodizing material.

21. A method according to any one of claims 19-20, characterized in that the chemical bath prepared for coating the bottom layer on the substrate surface comprises at least one electrolyte anodizing material at a value in the range of 1% to 20% of the total weight of the chemical material contained therein.

22. A method according to any one of claims 19-21 , characterized in that the chemical bath prepared for the bottom layer comprises at least one of cobalt sulfate and / or cobalt nitrate compounds as the corrosion inhibitor.

23. A method according to any one of claims 19-22, characterized in that the chemical bath prepared for coating the bottom layer on the substrate surface comprises at least one corrosion inhibitor at a value in the range of 1 % to 20% of the total weight of the chemical material contained therein.

24. A method according to any one of claims 13-23, characterized in that the chemical bath prepared for the middle layer comprises at least one from the group consisting of dihydrogen phosphate, ammonium dihydrogen phosphate, monocalcium phosphate compounds as the phosphorus-based compound.

25. A method according to claim 24, characterized in that the chemical bath prepared for coating the middle layer on the substrate surface comprises phosphorus or phosphorus-based compound at a value of 5% to 75% of the total weight of the chemical material contained therein.

26. A method according to claim 25, characterized in that the chemical bath prepared for coating the middle layer on the substrate surface comprises phosphorus or phosphorus-based compound at a value of 8% to 60% of the total weight of the chemical material contained therein.

27. A method according to claim 26, characterized in that the chemical bath prepared for coating the middle layer on the substrate surface comprises phosphorus or phosphorus-based compound at a value of 10% to 50% of the total weight of the chemical material contained therein.

28. A method according to any one of claims 13-27, characterized in that the chemical bath prepared for the middle layer comprises at least one corrosion inhibitor, at least one electrolyte salt, at least one conductive agent, in addition to at least one phosphorus or phosphorus-based compound.

29. A method according to claim 28, characterized in that the chemical bath prepared for the middle layer comprises at least one of calcium (III) sulfate and / or calcium (III) nitrate compounds as the corrosion inhibitor.

30. A method according to any one of claims 28-29, characterized in that the chemical bath prepared for coating the middle layer on the substrate surface comprises the corrosion inhibitor at a value of 5% to 35% of the total weight of the chemical material contained therein.31 . A method according to any one of claims 28-30, characterized in that the chemical bath prepared for the middle layer comprises at least one of zinc nitrate, zinc chlorate, zinc sulfate, zinc phosphate, zinc molybdate, zinc chromate, zinc ricinoleate compounds as the electrolyte salt.

32. A method according to one of claims 28-31 , characterized in that the chemical bath prepared for coating the middle layer on the substrate surface comprises the electrolyte salt at a value of 2.5% to 10% of the total weight of the chemical material contained therein.

33. A method according to any one of claims 28-32, characterized in that the chemical bath prepared for the middle layer comprises at least one of 3- (benzthiazoyl-2-thio)-propylsulfonic acid sodium salt, 3-mercaptopropane-1 - sulfonic acid sodium salt, ethylenedithiodipropylsulfonic acid sodium salt, - disulfide disodium salt, bis(w-sulfobutyl)-disulfide disodium salt, bis-(w- sulfohydroxypropyl)-disulfide disodium salt, bis(w-sulfopropyl)-disulfide disodium salt, bis-(w-sulfopropyl)-sulfide disodium salt, methyl-(w-sulfopropyl) sodium salt, methyl-(w-sulfopropyl)-trisulfide disodium salt, O-ethyl-dithiocarbonic acid-S-(w- sulfopropyl)-ester, thiophosphoric acid-0-ethyl-bis((w-sulfopropyl)-ester disodium salt, thiophosphoric acid-tri(w-sulfopropyl)-ester trisodium salt, N,N- dimethyldithiocarbamic acid (3-sulfopropyl) ester sodium salt, 3- (2benzthiazolylthio)-1 -propanesulfonic acid sodium salt as the conductive agent.

34. A method according to any one of claims 28-33, characterized in that the chemical bath prepared for coating the middle layer on the substrate surface comprises the conductive agent at a value of 2.5% to 10% of the total weight of the chemical material contained therein.

35. A method according to any one of claims 28-34, characterized in that the chemical bath prepared for coating the middle layer on the substrate surface comprises at least one second electrolyte salt.

36. A method according to claim 35, characterized in that the chemical bath prepared for the middle layer comprises at least one of orthophosphoric acid, oligophosphoric acids, polyphosphoric acids, cyclo- or metaphosphoric acids,branched polyphosphates, paraphosphoric acid, thiophosphoric acid, perphosphoric acid, superphosphoric acid, hyperphosphoric acid as the second electrolyte salt.

37. A method according to any one of claims 35-36, characterized in that the chemical bath prepared for the middle layer comprises at least one second electrolyte salt at a value between 2.5% to 5% by weight.

38. A method according to any one of claims 13-37, characterized in that the substrate material is kept for a period between at least 10 to 15 minutes in a chemical bath prepared for the middle layer and having a temperature at a value between 55 °C to 80 °C.

39. A method according to any one of claims 13-38, characterized in that the chemical mixture prepared for the top layer comprises at least one polymeric material selected from a group consisting of polymers obtained from polyhydroxyethylmethacrylate, 2-methoxyl-1 -methylethyl acetate, 1 -methoxy 2- acetoxy propane 1 -methoxy 2-propyl acetate 1 -methoxy-2-propanol acetate, 1 - methoxy-2-propyl acetate, 2-acetoxy-1 -methoxypropane, 2-propanol, 1 -methoxy acetate, Dowanol PMA glycol ether acetate, methoxy propyl acetate, propylene glycol methyl ether acetate, propylene glycol monomethyl ether acetate monomers, PGMEA, PGMA polymers or a mixture thereof.

40. A method according to claim 39, characterized in that the chemical mixture prepared for the top layer comprises a polymeric material obtained from 2- methoxyl-1 -methylethyl acetate monomer as the polymeric material.

41. A method according to any one of claims 13-40, characterized in that the chemical mixture prepared for coating the top layer on the substrate surface comprises at least one polymeric-based compound at a value in the range of 30% to 85% of the total weight thereof.

42. A method according to any one of claims 13-41 , characterized in that the chemical mixture prepared for coating the top layer on the substrate surfacecomprises a composite material consisting of a reinforcing component based on an anti-corrosive additive in addition to a matrix based on a polymeric material.

43. A method according to claim 42, characterized in that the chemical mixture comprises at least one from the group consisting of trizinc bis(orthophosphate), zinc orthophosphate, trizinc phosphate, zinc phosphate and trizinc diphosphate, NasSC , K2CO3, CaCOs, MgO, AI2O3, SiC>2,BN, TiC>2 as the anti-corrosive additive.

44. A method according to any one of claims 42-43, characterized in that the chemical mixture prepared for coating the top layer on the substrate surface comprises the anti-corrosive additive at a value in the range of 2% to 20% the total weight thereof.

45. A method according to any one of claims 13-44, characterized in that the chemical mixture prepared for the top layer comprises at least one diluent in addition to at least one polymeric material and at least one anti-corrosive additive.

46. A method according to claim 45, characterized in that the chemical mixture prepared for the top layer comprises at least one of ethane, propane, butane, n- alkanes such as normal- and isopentane, cycloalkanes such as cyclopentane and cyclohexane, gas plant condensates (n-alkanes, naphthenes, aromatics, etc.) as the diluent.

47. A method according to any one of claims 45-46, characterized in that the chemical mixture prepared for coating the top layer on the substrate surface comprises the diluent at a value in the range of 5% to 10% of the total weight thereof.

48. A method according to any one of claims 45-47, characterized in that the chemical mixture prepared for the top layer comprises at least one second diluent.

49. A method according to any one of claims 45-48, characterized in that the chemical mixture prepared for coating the top layer on the substrate surfacecomprises the second diluent at a value in the range of 5% to 10% of the total weight thereof.

50. A method according to any one of claims 45-49, characterized in that the chemical mixture prepared for the top layer comprises butanol as the second diluent.51 . A method according to any one of claims 45-50, characterized in that the chemical mixture prepared for the top layer comprises at least one third diluent.

52. A method according to claim 51 , characterized in that the chemical mixture prepared for the top layer comprises at least one of cyclohexanol, cyclohexyl alcohol, hexahydrophenol, hydroxycyclohexane, hexaline compounds as the third diluent.

53. A method according to any one of claims 51 -52, characterized in that the chemical mixture prepared for coating the top layer on the substrate surface comprises the third diluent at a value in the range of 5% to 10% of the total weight thereof.

54. A method according to any one of claims 13-53, characterized in that the top layer is coated on the substrate material for a period between 90 to 270 minutes using a chemical mixture prepared for the top layer of the substrate material and having a temperature at a value between 20 °C to 45 °C.

55. A method according to one of claims 13-54, characterized in that the substrate material coated with the top layer is subjected to curing processes at a temperature value between 70 to 80 °C for a period between 10 to 15 minutes.

56. A coating according to any one of the preceding claims, characterized in that it has a thickness at a value between 5 to 15 microns.

57. Use of a coating according to any one of the preceding claims, characterized in that it is a coating material used for coating connecting elements and sheet materials in the automotive sector.

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