Machine component part having coating and method for production thereof

Abstract

The invention relates to a machine component part (10) having a first tribological surface which is adapted to be in contact with a second tribological surface of another machine component part (20) during machine operation, at least a portion of the first tribological surface being covered with a coating comprising a first coating (11) and a second coating (12), the first coating comprises a protective coating component and the second coating comprises an organic modified silane component wherein an organic modified silane used in the organic modified silane component contains one or more amine groups wherein the first coating is in direct contact with at least a portion of the first tribological surface, and wherein the second coating is in direct contact with at least a portion of the second tribological surface. The second coating is in direct contact with at least a portion of the first coating. The invention further relates to: a method for producing a coating on a first tribological surface of a first machine component; the invention also relates to the use of the coating for protecting components of a machine.

Description

Technical Field

[0001] The present invention relates to: a machine component having a first tribological surface, which is suitable for contacting with a second tribological surface of another machine component during machine operation, wherein at least a portion of the first tribological surface is covered with a coating; a method for preparing a coating on at least a portion of the first tribological surface of a first machine component, which is suitable for contacting with the second tribological surface of another machine component during machine operation; and a use of a coating on at least a portion of the first tribological surface of a first machine component for protecting the first machine component. Background Art

[0002] In applications where sliding or rolling contact between two tribological surfaces occurs under non-optimal conditions, such as when excessive loads are experienced or contaminated lubrication is present which causes corrosion, premature wear and fretting of the bearing may occur.

[0003] Therefore, in addition to or instead of using a lubricant, it can be beneficial to apply a protective coating to the tribological surface (in contact with another surface) of a machine component. There are many different types of coatings, including, for example, electroplated coatings, polymer coatings, thermal spray coatings, and chemically prepared coatings.

[0004] Two common types of inorganic protective coatings are chemically prepared black oxide coatings and manganese phosphate coatings. Black oxide coatings are black conversion layers formed when steel is oxidized under controlled caustic conditions to produce specific iron oxide species at the surface. Manganese phosphate coatings are gray to black layers formed when machine components are immersed in manganese phosphate fluids and the iron in the machine components reacts with manganese cations and phosphate anions in the fluid. Although these inorganic protective coatings provide many advantages for bearing performance, such as anti-wear performance, anti-corrosion performance, and anti-fretting performance, they still have room for improvement.

[0005] It is an object of the present invention to provide an inorganic protective coating, such as black oxide coatings and manganese phosphate coatings, which provides improved rolling properties compared to known organic protective coatings. Summary of the invention

[0006] It has now been found that this object can be achieved when using a specific additional coating which is applied to the conventional coating.

[0007] Therefore, the present invention relates to a machine component having a first tribological surface, which is suitable for contacting with a second tribological surface of another machine component during machine operation, wherein at least a portion of the first tribological surface is covered with a coating comprising a first coating layer and a second coating layer, wherein the first coating layer comprises a protective coating component and the second coating layer comprises an organic modified silane component, wherein the organic modified silane used in the organic modified silane component contains one or more amine groups, wherein the first coating layer is in direct contact with at least a portion of the first tribological surface, and wherein the second coating layer is in direct contact with at least a portion of the first coating layer.

[0008] The inorganic protective coating component is suitably a chemically prepared coating component.

[0009] In a preferred embodiment, the protective coating component comprises one or more iron oxides. Suitably, the inorganic protective coating component comprises at least Fe3O4. Preferably, the protective coating component comprises a black oxide.

[0010] Therefore, the present invention relates to a machine component having a first tribological surface, which is suitable for contacting with a second tribological surface of another machine component during machine operation, wherein at least a portion of the first tribological surface is covered with a coating comprising a first coating and a second coating, wherein the first coating comprises an inorganic protective coating component, the inorganic protective coating component comprises one or more iron oxides, and the second coating comprises an organic modified silane component, wherein the organic modified silane used in the organic modified silane component contains one or more amine groups, wherein the first coating is in direct contact with at least a portion of the first tribological surface, and wherein the second coating is in direct contact with at least a portion of the first coating.

[0011] In another preferred embodiment, the inorganic protective coating component includes manganese phosphate (Mn3(PO4)2) and / or hydrated manganese hydrogen phosphate (Mn5H2(PO4)4).

[0012] Therefore, the present invention also relates to a machine component having a first tribological surface, which is suitable for contacting with a second tribological surface of another machine component during machine operation, wherein at least a portion of the first tribological surface is covered with a coating comprising a first coating and a second coating, wherein the first coating comprises an inorganic protective coating component, the inorganic protective coating component comprises manganese phosphate and / or hydrated manganese hydrogen phosphate, and the second coating comprises an organic modified silane component, wherein the organic modified silane used in the organic modified silane component contains one or more amine groups, wherein the first coating is in direct contact with at least a portion of the first tribological surface, and wherein the second coating is in direct contact with at least a portion of the first coating.

[0013] Preferably, the inorganic protective coating component comprises manganese phosphate (Mn3(PO4)2).

[0014] Therefore, the present invention also relates to a machine component having a first tribological surface, which is suitable for contacting a second tribological surface of another machine component during machine operation, wherein at least a portion of the first tribological surface is covered with a coating comprising a first coating and a second coating, wherein the first coating comprises an inorganic protective coating component, the inorganic protective coating component comprises manganese phosphate, and the second coating comprises an organic modified silane component, wherein the organic modified silane used in the organic modified silane component contains one or more amine groups, wherein the first coating is in direct contact with at least a portion of the first tribological surface, and wherein the second coating is in direct contact with at least a portion of the first coating.

[0015] The thickness of the second coating used according to the present invention is suitably in the range 25 nm to 500 nm, preferably in the range 25 nm to 250 nm, more preferably in the range 50 nm to 200 nm, most preferably in the range 50 nm to 150 nm.

[0016] Improved bearing performance obtained using the second coating. In the case where the inorganic protective coating component includes one or more iron oxides (i.e., black oxide), an improved run-in process is obtained using the second coating because the second coating generates less noise and friction when compared to a coating made of black oxide alone. In addition, the second coating improves oil adhesion, thereby improving lubrication performance after run-in. In this case, a relatively smooth coating surface is obtained.

[0017] In the case where the inorganic protective coating component comprises manganese phosphate (Mn3(PO4)2) and / or hydrated manganese hydrogen phosphate (Mn5H2(PO4)4), improved wear resistance, friction reduction and corrosion resistance are obtained using the second coating. When the organo-modified silane according to the present invention is used, longer operating times can be established. The surface of the manganese phosphate crystals will be covered with the organo-modified silane, whereby the organo-modified silane containing one or more amino groups will act as an elastomeric binder that holds the manganese phosphate crystals together, ensuring improved retention of the manganese phosphate crystals during use and lubricant attachment, and thus obtaining improved wear resistance, friction reduction and corrosion resistance. In addition, at least a portion of the organo-modified silane will penetrate the porous structure of the first coating comprising manganese phosphate crystals, thereby providing an adhesive coating also between the manganese phosphate crystals that are not arranged immediately at the outer surface of the first coating. This internal bonding in the porous structure of the first coating containing manganese phosphate further contributes to the high retention of the manganese phosphate crystals in the first coating, and thereby contributes to improved performance.

[0018] Therefore, in a preferred embodiment of the present invention, the inorganic protective coating component in the first coating comprises manganese phosphate, wherein at least a portion of the second coating comprising an organically modified silane containing one or more amino groups covers the outer surface of the first coating, and wherein at least a portion of the second coating has penetrated the inner portion of the first coating.

[0019] According to the present invention, the organo-modified silane used in the organo-modified silane component contains one or more amino groups. Preferably, the organo-modified silane contains two or more amine groups. More preferably, the organo-modified silane contains two amine groups. Organo-modified silanes containing one or more amino groups have the following advantages: they show improved adhesion to the first coating including the protective coating, improved performance in terms of anti-wear performance, anti-corrosion performance and anti-fretting performance over a longer period of time. One or more amino groups will react with metal ions (such as manganese ions (Mn 2+ ) and iron ions (Fe 2+ and Fe 3+ )) forms a strong coordination bond. In addition, one or more amino groups improve the corrosion inhibition performance of the coating. Therefore, when compared with organic modified silanes that do not contain amino groups and require organic solvents (such as 1,2-bis(triethoxysilyl)ethane and triethoxysilylpropoxy(polyethyleneoxy)dodecanoate as examples), organic modified silanes containing one or more amino groups will appear more attractive.

[0020] Preferably, the organo-modified silane used in the organo-modified silane component used according to the present invention is water-soluble. Suitably, the organo-modified silane used in the organo-modified silane component has R-Si-(OX)3 structure, wherein R is an organic functional group, and X is independently hydrogen or alkyl, preferably methyl or ethyl. The first, second and third X can be identical or different. For example, the first and second X can be identical, and the third X is different from the first and second X. Preferably, the first, second and third X are all identical. More preferably, X is hydrogen (that is, the first, second and third X are hydrogen).

[0021] Suitably, R contains 1 to 50 carbon atoms, preferably 5 to 20 carbon atoms. R contains one or more amine groups. R may also contain one or more unsaturated CC bonds. Preferably, R contains two or more amine groups. More preferably, R contains two amine groups. The organic modified silane is suitably selected from the group of monomers or oligomers consisting of the following: 4-aminobutyltriethoxysilane, 4-amino-3,3-dimethylbutyltrimethoxysilane, 4-amino-3,3-dimethylbutylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminoisobutylmethyldimethoxysilane, N (2-aminoethyl)-3-aminopropylmethyldiethoxysilane, N(2-aminoethyl)-3-aminopropylethyldimethoxysilane, (trimethoxysilylpropyl)diethylenetriamine, 3-(N-allylamino)propyltrimethoxysilane, n-butylaminopropyltrimethoxysilane, (3-N-ethylamino)isobutylmethyldiethoxysilane, (3-N-ethylamino)isobutyltriethoxysilane, N-methylaminopropylmethyl trimethoxysilane, N-methylaminopropyl trimethoxysilane, 3-(N,N-dimethylaminopropyl) aminopropyl methyl dimethoxysilane, N-(2-aminoethyl)-3-aminopropyl triethoxysilane, 3-aminopropyl triethoxysilane, 3-aminopropyl trimethoxysilane, N-(2-aminoethyl)-3-aminopropyl silane triol, N-(2-aminoethyl)-3-aminoisobutyl dimethyl silane triol, n-butyl Aminopropyl silanetriol, 4-aminobutyl silanetriol, 4-amino-3,3, dimethylbutyl silanetriol, 3-aminopropyl silanetriol, N-(2-aminopropyl)-3-aminopropyl silanetriol, 3-mercaptopropyl silanetriol, aminoethyl silsesquioxane, aminoethylaminopropyl silsesquioxane, N-(2-aminoethyl)-3-aminopropyl silanetriol, and N-(2-aminoethyl)-3-aminoethyl silanetriol.

[0022] As indicated above, in the organo-modified silane used according to the present invention, X is preferably hydrogen. Preferably, the organo-modified silane is selected from the group consisting of aminoethylsilsesquioxane, aminoethylaminopropylsilsesquioxane and N-(2-aminoethyl)-3-aminopropylsilanetriol. More preferably, the organo-modified silane is aminoethyl-aminopropylsilsesquioxane or N-(2-aminoethyl)-3-aminopropylsilanetriol. Most preferably, the organo-modified silane used in the organo-modified silane component is N-(2-aminoethyl)-3-aminopropylsilanetriol. A mixture of organo-modified silanes can also be used. The example of this mixture includes aminoethyl-aminopropylsilsesquioxane and N-(2-aminoethyl)-3-aminopropylsilanetriol.

[0023] The organomodified silane component may include an organomodified silane whereby one or more of the amino groups of the organomodified silane has been reacted with another chemical compound (eg, an ester) to provide a coating having specific surface properties.

[0024] In case the first coating comprises manganese phosphate (Mn3(PO4)2) and / or hydrated manganese hydrogen phosphate (Mn5H2(PO4)4), one or more functional groups present in the R group of the organo-modified silane (such as one or more amine groups and / or sulfate groups) are able to form a coordination structure with the manganese cations, ensuring that the second coating is firmly bonded to the first coating, thereby providing a very stable coating with improved adhesion behavior and thus improved bearing performance in terms of wear reduction and corrosion resistance.

[0025] The first coating is in direct contact with at least a portion of the first tribological surface of the machine component. Preferably, the first coating is in direct contact with more than 75% of the first tribological surface, preferably more than 95% of the first tribological surface. Most preferably, the entire first tribological surface is covered with the first coating. Suitably, the second coating is in direct contact with at least a portion of the first coating. Preferably, the second coating is in direct contact with more than 75% of the first contact layer, more preferably more than 95% of the first contact layer. Most preferably, the entire first coating is covered with the second coating.

[0026] The invention also provides a method for preparing a coating on at least a portion of a first tribological surface of a first machine component, the first tribological surface being adapted to come into sliding contact with a second tribological surface of another machine component during machine operation, the method comprising the following steps:

[0027] (a) applying a first coating to at least a portion of the first tribological surface, the first coating comprising a protective coating component, and wherein the first coating is in direct contact with at least a portion of the first tribological layer;

[0028] (b) applying a second coating layer onto at least a portion of the first coating layer, the second coating layer comprising an organo-modified silane, wherein the organo-modified silane used in the organo-modified silane component contains one or more amine groups, and wherein the second coating layer is in direct contact with at least a portion of the first coating layer; and

[0029] (c) allowing the second coating to cure.

[0030] According to the present invention, the organo-modified silane used in the organo-modified silane component contains one or more amino groups. These organo-modified silanes containing one or more amino groups make the method for preparing the coating including the first coating and the second coating according to the present invention very attractive. The one or more amino groups present in the organo-modified silane enable the curing of the second coating to be carried out at room temperature (i.e., avoiding the use of an oven) and during a relatively short curing cycle. Another advantage of using an organo-modified silane containing one or more amino groups is that the organo-modified silane can be applied to at least a portion of the first coating in the form of an aqueous solution, and no organic solvent is required, thereby obtaining an environmentally friendly and safe manufacturing method ( / process / process). Another advantage is the fact that when compared with an organo-modified silane that does not contain an amino group and requires an organic solvent (such as 1,2-bis(triethoxysilyl)ethane and triethoxysilylpropoxy(polyethyleneoxy)dodecanoate as an example), an aqueous solution of an organo-modified silane containing one or more amino groups shows improved stability. This means that an aqueous solution of an organo-modified silane containing one or more amino groups can be stored for a long time until needed.

[0031] In step (a), a first coating is applied to at least a portion of a first tribological surface of a machine component. Preferably, the first coating is applied to more than 75% of the first tribological surface, preferably to more than 95% of the first tribological surface. Most preferably, the first coating is applied to the entire first tribological surface. In step (b), a second coating is applied to at least a portion of the first coating. Preferably, the second coating is applied to more than 75% of the first contact layer, preferably to more than 95% of the first contact layer. Most preferably, the second coating is applied to the entire first coating.

[0032] Step (a) is carried out under conditions commonly used for applying inorganic protective layers on tribological surfaces of machine components. Such methods include conversion coating by chemical impregnation, vacuum deposition including PVD technology (physical vapor deposition), thermal spraying and kinetic spraying techniques.

[0033] According to the present invention, in step (b), the organo-modified silane can be suitably applied to at least a portion of the first coating layer by means of a dip coating, contact coating, roller coating or spray coating method. Preferably, the polymer formulation is applied to at least a portion of the first coating layer by means of a spray coating, spin coating or dip coating method or a combination of these methods.

[0034] The organo-modified silane may be any of those described herein above. Preferably, in the organo-modified silane used, X is hydrogen. The organo-modified silanes in which X is hydrogen have the following advantages: they are water-soluble and can avoid the use of environmentally unfriendly organic solvents. Therefore, in step (b), the organo-modified silane is preferably in the form of an aqueous solution applied to at least a portion of the first coating.

[0035] Step (b) is suitably carried out over a period of time in the range of less than 1 minute to 15 minutes and at a temperature in the range of 5° C. to 80° C. Preferably, step (b) is carried out over a period of time in the range of less than 1 minute to 5 minutes and at a temperature in the range of 15° C. to 35° C.

[0036] When an aqueous solution containing an organomodified silane wherein X is hydrogen is used in step (b), the organomodified silane is present in an amount ranging from 0.1 to 25 wt %, preferably from 0.5 to 5 wt %, based on the total weight of the aqueous solution.

[0037] When X is an alkyl group (such as a methyl group or an ethyl group), an organic solution in which the organo-modified silane is dissolved in a solvent is used. In this case, the organo-modified silane is present in an amount in the range of 0.1 wt % to 20 wt %, preferably in the range of 0.5 wt % to 5 wt %, based on the total weight of the organic solution.

[0038] Suitably, the solvent is a polar organic solvent. The polar solvent can be a polar aliphatic solvent or a polar aromatic solvent, such as an alcohol, a ketone, an ester, an acetate, a glycol ether, a non-protonic amide, a non-protonic sulfoxide or a non-protonic amine. Examples of useful solvents include methyl ethyl ketone, methyl isobutyl ketone, m-amyl acetate, ethylene glycol butyl ether-acetate, propylene glycol monomethyl ether acetate, xylene, n-methyl pyrrolidone or a blend of aromatic hydrocarbons. Suitable alcohols include ethanol, isopropanol, n-butanol and n-propanol. Suitable acetates include hexyl acetate, octyl acetate and glycol ether acetate, such as propylene glycol monomethyl ether acetate. Suitable ketones include methyl propyl ketone, methyl isobutyl ketone and methyl hexyl ketone. Glycol ether and glycol ether acetate are particularly preferred. Acidic or basic catalysts can also be added. In addition, the solvent can include non-polar aromatic and / or aliphatic solvents.

[0039] Step (c) is suitably carried out over a period of time in the range of 3 days to 30 days and at a temperature in the range of 5°C to 80°C. Preferably, step (d) is carried out over a period of time in the range of 7 days to 21 days and at a temperature in the range of 15°C to 30°C. Step (c) will cure the coating by drying. Once the second coating has cured, the first component is ready for use.

[0040] The present invention also relates to the use of a coating on at least a portion of a first tribological surface of a first machine component for protecting the first machine component, the first tribological surface being suitable for contact with a second tribological surface of another machine component during machine operation, the coating comprising a first coating and a second coating, wherein the first coating comprises a protective coating component and the second coating comprises an organic modified silane, wherein the organic modified silane used in the organic modified silane component contains one or more amine groups, wherein the first coating is in direct contact with at least a portion of the first tribological surface, and wherein the second coating is in direct contact with at least a portion of the first coating. Preferably, the present coating is also used on at least a portion of the second tribological surface of other machine components.

[0041] The use of a coating comprising a first coating and a second coating according to the invention provides attractive properties in rolling applications, where high contact pressures are required between the tribological surfaces of machine components in order to establish adequate hydrodynamic lubrication.

[0042] Therefore, in a preferred embodiment, the present invention relates to the use of a coating on at least a portion of a first tribological surface of a first machine component for protecting the first machine component in a rolling roller application, wherein the first tribological surface is suitable for rolling contact with a second tribological surface of another machine component during machine operation, the coating comprising a first coating and a second coating, wherein the first coating comprises a protective coating component, the protective coating component comprises manganese phosphate, and the second coating comprises an organic modified silane, wherein the organic modified silane used in the organic modified silane component contains one or more amine groups, wherein the first coating is in direct contact with at least a portion of the first tribological surface, and wherein the second coating is in direct contact with at least a portion of the first coating.

[0043] Preferably, the present coating is also applied on at least a portion of the second tribological surface of other machine components.

[0044] The invention also relates to a machine comprising a first machine component on which a coating is formed using the method according to the invention and a second machine component in contact with the first machine component.

[0045] The machine according to the invention is suitably a closed machine, wherein the first machine component and the second machine component are not exposed to external conditions, such as weather conditions.

[0046] In one embodiment, the first machine component and the second machine component form part of a dynamic seal assembly, the dynamic seal assembly comprising a dynamic seal having a contact lip bearing against a counterface. The counterface may be the surface of a shaft rotating relative to the seal or a component fixedly mounted to the shaft, such as an oil slinger or a bearing inner ring. In another example, the counterface is the surface of a cylinder housing or a piston linearly displaceable relative to the seal. The coating may be provided on the contact surface of the sealing lip and / or on the counterface.

[0047] Dynamic seals can therefore be used to seal passages between machine components that move linearly or in a circumferential direction relative to each other. Dynamic seals can be, for example, lip seals of rolling bearings, engine seals (such as valve stem seals, crankshaft seals or shaft seals as examples), O-ring seals, steering seals, suspension seals, piston seals, wheel end seals, power transmission seals, pneumatic seals, hydraulic seals, fluid handling seals or aviation shaft seals.

[0048] In another embodiment, the first machine component and the second machine component form part of a sliding bearing assembly. In one example, the sliding bearing assembly is a radial component, which includes radial surfaces oriented relative to each other in sliding contact with each other for supporting and transmitting radial loads. One of the first component and the second component is an internal component, such as a shaft or a component fixedly mounted to the shaft, such as a sleeve, a bushing or an inner ring of a sliding bearing. The other of the first component and the second component is an external component, such as a housing or a component fixedly mounted to the housing, such as an outer ring of a sliding bearing or a sleeve or a bushing. The coating can be provided on the radial outer surface of the internal component and / or on the radial inner surface of the external component. In another example, the sliding bearing assembly is a thrust bearing assembly, which includes axial surfaces oriented relative to each other in sliding contact with each other, wherein the coating is provided on one or both axial surfaces.

[0049] The first machine component may suitably be derived from a ferrous material, such as selected from the group consisting of chromium steel and stainless steel. Examples of suitable stainless steels include martensitic grades such as 410 and 410H, austenitic grades such as 304 and 316, ferritic grades such as 410S, duplex grades such as 2205, and precipitation hardening grades such as 17-4PH. Preferably, the first machine component is made of steel.

[0050] Coatings produced according to the invention can also be used advantageously in rotary sealing applications.

[0051] In an alternative embodiment, the outer surface of the shaft or a sleeve mounted to the shaft is provided with a coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] exist Figure 1 , a machine component according to the present invention is shown, the machine component comprising an outer sliding element 10 of a sliding bearing as the machine component, a first coating 11, a second coating 12 and an inner sliding element 20 of a sliding bearing as another machine component.

[0053] The advantages of the present invention will become apparent from the following examples. DETAILED DESCRIPTION

[0054] Example 1

[0055] Water-based sol-gel coatings on steel parts coated with manganese phosphate

[0056] The silane 2-aminoethyl-3-aminopropylsilanetriol was obtained as a 25 wt% concentrated aqueous solution (Gelest Inc.) This was then diluted in tap water to a concentration of 1% by volume and mixed thoroughly to make a sol-gel processing solution.

[0057] Several flat steel coils (about 5 cm in diameter) made of grade 3 steel, previously surface treated to produce a manganese phosphate coating, were thoroughly cleaned; immersed once in 2-propanol and twice in 2-butanone (HPLC grade), followed by additional rinses in 2-butanone of the same grade. The sample coils were then allowed to dry.

[0058] The cleaned phosphated steel coil was then briefly dipped into the sol-gel solution and then steadily withdrawn at a rate of approximately 2 cm per second. The coil was held above the dipping solution until most of the wet coating was removed by gravity and then placed on a flat surface to dry at room temperature for 2 weeks.

[0059] The result achieved was a contact angle with deionized water of between 65° and 70°, which represents a significantly increased hydrophobicity compared to a clean but unmanganese phosphate coated steel component with a contact angle of less than 10°. Increased hydrophobicity is a clear indicator of increased wear resistance.

[0060] Example 2

[0061] Solvent-based sol-gel coatings on black oxide coated steel parts

[0062] A mixture of deionized water (10 ml) and 2-propanol (70 ml) was added to a glass beaker and stirred continuously with a magnetic stirring bar. Two drops of acetic acid (diluted) were then added, followed by 0.4 ml of silane 1,2-bis(triethoxysilyl)ethane (96% purity, Merck KGaA) and 2.0 ml of silane triethoxysilane propoxy(polyethyleneoxy) dodecanoate (Gelest GmbH, 95%). The solution was heated to approximately 60°C for 1 hour and stirred and cooled throughout the mixing and reaction process.

[0063] Several flat steel coils (approximately 5 cm in diameter) made of grade 3 steel, previously surface treated to produce a black oxide coating, were thoroughly cleaned; immersed once in 2-propanol and twice in 2-butanone (>99.9%), followed by additional rinses in the same grade of 2-butanone. The sample coils were then allowed to dry.

[0064] The cleaned black oxide treated steel coil was then briefly dipped into the sol-gel solution and then steadily withdrawn at a rate of approximately 2 cm per second. The coil was held above the dipping solution until most of the wet coating was removed by gravity, and then laid flat for 5 minutes for initial drying before being heated in an oven at 100°C for 1 hour.

[0065] The resulting coated part had a slightly darker appearance than the uncoated circle, and had a contact angle with deionized water of approximately 65°, indicating increased hydrophobicity compared to the cleaned uncoated black oxide circle (contact angle with deionized water of approximately 0°).

[0066] Example 3

[0067] Water-based sol-gel coatings on black oxide coated steel parts

[0068] The sol-gel prepared using Example 1 was also applied to the cleaned black oxide treated Grade 3 steel rims using the same cleaning and treatment used in Experiment 2.

[0069] As a result, a contact angle with deionized water of approximately 65° was achieved, whereas for clean but uncoated steel parts a contact angle with deionized water of approximately 0° was obtained.

[0070] Example 4

[0071] Emulsion process for sol-gel coating on steel parts coated with manganese phosphate

[0072] 0.4 ml of silane 1,2-bis(triethoxysilyl)ethane (96% purity, Merck KGaA), 2.0 ml of silane triethoxysilane propoxy(polyethyleneoxy) dodecanoate (Gelest Co., Ltd., 95%) and 2 drops of dilute acetic acid were added to 50 ml of deionized water and stirred vigorously using a magnetic bar. About 2 ml of an aqueous solution containing Polaxomer 407 surfactant was added to obtain a concentration of about 0.1% w / w in the final mixture, and vigorous stirring was maintained until a turbid emulsion of silane droplets in water was obtained.

[0073] The manganese phosphate treated rings were cleaned using the same method as in Example 1. A portion of the emulsion / suspension prepared above was poured onto the cleaned manganese phosphate coated rings and the excess was poured off. The coated rings were then placed in an oven at 100°C for 1 hour to produce a cured coating which, after cooling, produced a contact angle with deionized water of approximately 45°, whereas for the cleaned but uncoated steel part, a contact angle with deionized water of approximately 0° was obtained.

[0074] Examples 1 to 4 clearly show that the use of a second coating according to the invention results in significantly improved hydrophobicity, which in turn leads to significantly increased wear and corrosion resistance.

[0075] Example 5

[0076] Water immersion rust prevention test of water-based sol-gel coatings on steel parts with manganese phosphate

[0077] The sol-gel coating made in Example 1 using 2-aminoethyl-3-aminopropylsilanetriol on a manganese phosphate ring (which had also been previously tested for MTM tribology testing) was cleaned and placed in a beaker of tap water and maintained at 70°C for 4 days. At the same time, a reference ring with manganese phosphate but not sol-gel treated (which had also been previously tested tribology in the same manner using MTM) was placed in a separate beaker of water under the same conditions. The parts were then removed after these 4 days and gently wiped dry before the parts were inspected for rust. The samples coated with sol-gel showed very little red rust compared to the reference samples without sol-gel coating, which showed more red from the rust. SEM with EDS (energy dispersive x-ray spectroscopy) was also used to confirm the increase in oxygen levels in the more rusty areas of the reference samples that were not sol-gel treated.

[0078] Example 6

[0079] Potentiodynamic measurements of components coated with manganese phosphate by solvent sol-gel treatment

[0080] Potentiodynamic polarization was performed in a double housing cell using a three-electrode system. The steel sample served as the working electrode. A platinum electrode served as the auxiliary electrode, and silver / silver chloride served as the reference electrode. The reference electrode was inserted into the drag capillary to minimize the potential difference between the two ends of the conducting phase during current flow.

[0081] The experiments were carried out in 3.5 wt% NaCl solution using a VersaSTAT 3F potentiostat galvanostat from AMETEK with continuous nitrogen purge at two temperatures (21°C and 60°C). Before each experiment, the steel specimens were immersed in 3.5% NaCl solution for 180 minutes to reach steady state. Potentiodynamic anodic and cathodic polarization diagrams were obtained from -1200 mV (relative to the reference electrode) to +700 mV (relative to the reference electrode potential) at a scan rate of 0.0833 mV / s.

[0082] The following values ​​were obtained for the manganese phosphate plate coated with the sol-gel from Example 2 containing triethoxysilyl propoxy (polyethyleneoxy) dodecanoic acid and bis (triethoxysilyl) ethane. One reading was taken with the sol-gel taken directly after the heat treatment without cleaning, and the other reading was taken with the sol-gel coating cleaned to remove any residue that might obscure the true value associated with the solid sol-gel coating formed. This successfully demonstrates that the sol-gel coating provides a much lower I corr , suggesting that it would provide useful improvements in corrosion resistance.

[0083] The results are shown in Table 1.

[0084] Table 1

[0085] sample <![CDATA[E corr (mV)]]> <![CDATA[I corr (μA)P i (%)]]> Manganese phosphate reference -694 1.428- Manganese phosphate + sol-gel (not cleaned after deposition) -682 0.090 93.7 Manganese phosphate + sol-gel (cleaned after deposition) -431 0.308 78.5

[0086] Example 7

[0087] Tribology of solvent-based sol-gel coatings on black oxide coated parts

[0088] The tribological behavior of the sol-gel prepared by Example 1 was studied using a micro-traction machine (MTM2). The MTM is a ball-on-disc tester from PCS Instruments. The contact pressures, velocities, and temperatures that can be achieved in an MTM2 contact are similar to those occurring in gears, rolling bearings, and cams.

[0089] The ball used is a superfinished AISI 52100 (535A99) test ball, R q The sol-gel on black oxide and black oxide treated steel discs was of grade 3 steel with an initial Rq of 250 nm for uncoated steel. A formulated mineral oil (Lukoil Genesis 0W20) was used for each experiment.

[0090] The parameters used to study the friction and tribofilm formation are shown in Table 2. Stribeck and duration tests were performed and each test was repeated twice to check the reproducibility of the results.

[0091] Table 2

[0092]

[0093] Table 3 shows the lower friction established during the initial run-in phase of the test.

[0094] Table 3

[0095]

[0096] Example 8

[0097] Deposition onto cylindrical bearing units

[0098] A water-based sol-gel treatment prepared using the same method as in Example 1 was also deposited onto a cleaned, manganese phosphate treated cylindrical roller bearing of 10 mm diameter x 20 mm length. This part was cleaned and coated using the same process and when fully cured produced very similar contact angles and appeared to be of good quality and uniformity.

[0099] Example 9

[0100] Tribology of water-based sol-gel coatings on parts coated with manganese phosphate

[0101] The tribological behavior of water-based sol-gel produced from the sol-gel prepared in Example 1 on manganese phosphate was also studied using the same MTM (miniature pulling machine) as used in Example 7. Stribeck tests were performed on the samples and compared with reference samples of manganese phosphate coatings without sol-gel treatment.

[0102] A sequence of 6 Stribeck steps was programmed, with speed varying from high to low speeds between 50 mm / s and 2500 mm / s, repeated 3 times, with the test parameters shown in Table 4. The average traction coefficient was then measured at different speeds and / or spin-to-roll ratios during 3 duration steps of 5 minutes each as shown in Table 5. The test results are shown in Table 6.

[0103] Table 4 - Test conditions for friction test

[0104]

[0105] Table 5 - Description of each step

[0106] parameter Step 1 Step 2 Step 3 Speed(mm / s) 500 500 150 SRR (%) 50 100 100

[0107] Table 6 - Results

[0108]

[0109] After completing the test, the profile of each wear track in tribological contact was measured and the maximum wear depth was recorded (see Table 7).

[0110] Table 7 - Wear depth of samples

[0111] sample Wear depth(μm) Reference manganese phosphate steel 6.1 (average) Sol-gel on manganese phosphate steel 2.8

[0112] It is clear from Table 7 that the use of sol-gel coated on Mn phosphate steel significantly reduces the wear depth, indicating that the sol-gel acts as a binder, which allows much less Mn phosphate crystals to be lost from the first coating during operation.

[0113] In addition, the water-based sol-gel used in Example 1 could be stored for one month without showing any precipitation, whereas the solvent-based sol-gel used in Example 2 showed clear precipitation already after 2.5 days of storage.

[0114] Examples 5 to 9 also demonstrate that the second coating used in accordance with the present invention produces improved anti-corrosion and anti-fretting properties when compared to embodiments using only the first coating.

Claims

1. A machine component having a first tribological surface adapted to contact a second tribological surface of another machine component during operation of the machine, wherein: At least a portion of the first tribological surface is covered with a coating comprising a first coating and a second coating, wherein the first coating comprises a protective coating component and the second coating comprises an organo-modified silane component, wherein the organo-modified silane used in the organo-modified silane component contains one or more amine groups, wherein the first coating is in direct contact with at least a portion of the first tribological surface, and wherein the second coating is in direct contact with at least a portion of the first coating.

2. The machine component according to claim 1, characterized in that: The organo-modified silane used in the organo-modified silane component is water-soluble.

3. The machine component according to claim 1 or 2, characterized in that: The organo-modified silane is selected from the group consisting of aminoethylsilsesquioxane, aminoethylaminopropylsilsesquioxane and 2-aminoethyl-3-aminopropyl-silanetriol.

4. The machine component according to claim 3, characterized in that: The organo-modified silane is aminoethyl-aminopropyl silsesquioxane or 2-aminoethyl-3-aminopropyl-silanetriol.

5. The machine component according to any one of claims 1 to 4, characterized in that: The thickness of the second coating layer is in the range of 25 nm to 500 nm.

6. The machine component according to any one of claims 1 to 7, characterized in that: The protective coating component includes manganese phosphate and / or hydrated manganese hydrogen phosphate.

7. The machine component according to any one of claims 1 to 6, characterized in that: The protective coating component includes manganese phosphate.

8. A method for preparing a coating on at least a portion of a first tribological surface of a first machine component, the first tribological surface being adapted to come into contact with a second tribological surface of another machine component during machine operation, the method comprising the steps of: (a) applying a first coating to at least a portion of the first tribological surface, the first coating comprising a protective coating component, and wherein the first coating is in direct contact with at least a portion of the first tribological layer; (b) applying a second coating layer onto at least a portion of the first coating layer, the second coating layer comprising an organomodified silane comprising one or more amine groups, and wherein the second coating layer is in direct contact with at least a portion of the first coating layer; and (c) allowing the second coating to cure.

9. The method according to claim 8, characterized in that In step (b), an organomodified silane in the form of an aqueous solution is applied to at least a portion of the first coating.

10. The method according to claim 8 or 9, characterized in that: The organo-modified silane is selected from the group consisting of aminoethylsilsesquioxane, aminoethylaminopropylsilsesquioxane and 2-aminoethyl-3-aminopropylsilanetriol.

11. The method according to claim 10, characterized in that The organo-modified silane is aminoethyl-aminopropyl silsesquioxane or 2-aminoethyl-3-aminopropyl-silanetriol.

12. The method according to any one of claims 8 to 11, characterized in that The protective coating component includes manganese phosphate and / or hydrated manganese hydrogen phosphate.

13. The method according to claim 12, characterized in that The protective coating component includes manganese phosphate.

14. Use of a coating on at least a portion of a first tribological surface of a first machine component for protecting the first machine component, the first tribological surface being adapted to come into contact with a second tribological surface of another machine component during machine operation, the coating comprising a first coating and a second coating, wherein: The first coating comprises a protective coating component and the second coating comprises an organomodified silane comprising one or more amine groups, wherein the first coating is in direct contact with at least a portion of the first tribological surface, and wherein the second coating is in direct contact with at least a portion of the first coating.

15. Use in rolling mill applications according to claim 14, characterized in that The first tribological surface is adapted for rolling contact with the second tribological surface during operation of the machine, and wherein the first coating comprises a protective coating component comprising manganese phosphate.

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