WO2017178881A1 - Plain bearing with a polymeric coating for reducing friction in internal combustion engines, and method for producing same - Google Patents

Abstract

The present invention relates to a plain bearing with a polymeric coating for reducing friction in internal combustion engines. In addition, the present invention relates to the method for producing the plain bearing with a polymeric coating for reducing friction in internal combustion engines, in particular by introducing an adhesion layer between the metallic surface of the plain bearing and the polymeric coating, this layer being produced by previously immersing the plain bearing in a hydro-alcoholic solution of organo-silanes, followed by thermal curing, resulting in the formation of a polysiloxane film containing chemical groups which can have various interactions with the subsequent polymeric coating.

Description

 Polymeric-coated bearing for friction reduction in internal combustion engines and production process Fields of the invention

 The present invention relates to the field of friction in combustion engines. More specifically, the present invention relates to the polymeric coated friction bearing bearing in internal combustion engines. Additionally, the present invention relates to the process for the production of polymeric coated bearing friction bearings in internal combustion engines.

Description of the invention

[0002] The present invention relates to the process of coating aluminum or bronze alloy bearings consisting of: a first step of degreasing the metal surface using water, neutral detergent and organic solvent; a second step of basic surface activation with sodium hydroxide solution; a third stage of pretreatment of the metal surface with hydroalcoholic solutions of mono and bifunctional silanes, aiming at the formation of a polysiloxane film with the anchoring function of the polymeric coating, subsequently applied to the bronzine surface; a fourth step of condensation of silanes for polysiloxane film formation; a fifth step of applying the polymeric coating comprising poly (amide imide), poly (tetrafluoroethylene) and aluminum flakes; and a sixth heat curing step of the polymeric coating applied to the bearing. The composition of the mono and bifunctional hydroalcoholic solutions of silanes were also an object of development of this invention, as well as the time and temperature conditions of cure for polysiloxane film formation. Background of the invention

 Adherence of polymeric coatings to metallic surfaces requires their activation. This activation can be chemical, usually by basic attacks, acid attacks, phosphating, chroming and also by the deposition of oxides via sol-gel, whose main function is to generate chemically active groups and roughness that favor the adhesion of a polymeric coating. There is also mechanical activation, usually by blasting the metal surface with oxides, which mainly promotes the roughness of the metal surface providing physical anchor points of the polymeric coating. Currently, polymer-coated aluminum or bronze bearings generally have their surface activated by oxide blasting prior to the application of such a coating. This operation has as its main drawback the generation of residues on the metal surface, which can subsequently cause premature coating failure. By replacing this step with silane pretreatment, it is possible to promote chemical adhesion of the polymeric coating, eliminating the problem of blasting residue deposition and possible premature engine failure of the bearing.

The formation of metal oxides and hydroxides, as well as other corrosion products at the interface between the metal and a coating, may compromise the mechanical and electrical stability of the assembly. This formation is particularly pronounced in shy environments. In the case of aluminum its surface is naturally protected by a thin layer of oxide which provides passivation to the metal at room temperature and moderate relative humidity. Exposure to higher temperature and humidity induces the transformation of aluminum oxide into aluminum oxide hydroxide (AIO (OH)) and finally, if the transformation is complete, to aluminum hydroxide. aluminum (Al (OH) ₃ ).

 Changes in the chemical composition of the surface are accompanied by changes in the original morphology of the thin oxide layer to a flake structure and finally to a plate structure. These changes are associated with layers that are mechanically weaker and non-passivated. As it is possible to change the thickness of the oxide layer by these transformations, the mechanical integrity of the coating interface becomes weaker and may lead to mechanical separation between the substrate and the coating.

 Changing the roughness of the metal surface is a device for improving the adhesion of polymeric coatings and thus achieving structural durability in humid or corrosive environments. The most common practices for inserting or accenting surface roughness are: blasting, chemical activation or anodizing and each technique has its limitations.

In the last 20 years there has been a considerable growth in the number of studies and technologies developed with organic coupling agents that are capable of chemically bonding to the metal surface and also to a subsequent layer of epoxy resin-like polymeric coating, polyamides, silicones. and others.

 The prime examples of such coupling agents are organo silanes, organo titanates and organo zirconates. Typically, these compounds have a terminal group capable of reacting with one or more polymer families, examples of such groups are amino, mercapto and epoxy. Additionally, these compounds have one or more groups capable of binding to the metal substrate, such as alkoxy, aryloxy or halides.

In this context, it is known in the state of the art that most metals, when exposed to the atmosphere, form oxides on their surface. Hydroxide groups begin to associate with surface-formed oxides, especially when the metal is exposed to water, either in the atmosphere or by chemical reaction or by adsorption via hydrogen bonding or van der Waals force. When the organic coupling agent (organo silane, organo titanate, organo zirconate) comes into contact with this metal surface, hydrolysis of the alkoxy group occurs, for example bonded to the Si or Ti or Zr atom forming alcohol and bonding. (Si or Ti or Zr) -0-Metal. This reaction anchors the organic portion of the coupling agent to the metal substrate and allows another functional group at the end of the chain to be available to react with a polymeric coating. Among the organic coupling agents mentioned, organo silanes are the most studied and have the largest number of developed applications.

 Silanes are hybrid molecules containing functional organic groups such as methoxy and ethoxy bonded to the silicon atom. Some types of silanes have other functional groups besides those already mentioned, especially chlorine, amine, sulfur and epoxide. These are called functional silanes, in which additional functional groups promote adhesion with organic films, such as coating paints.

The ethoxy or methoxy groups are hydrolysed when water is added to the system, forming the silanols -Si-OH groups, which react with the hydroxide groups on the metal surface, resulting in a covalent chemical bond-type interface film. -Si-om. Unlike chemical conversion treatments such as "chromating" or zirconium / titanium conversion, where metal oxidation and species reduction govern surface conversion, silanes do not require the metal to participate electrochemically in the deposition mechanism of the metal. movie. The curing of the silane layer is considered essential considering its purpose of anti-corrosion protection. Heating of the coated substrates results in crosslinking between the silane molecules within the deposited film. Silanol groups, which have not reacted with the metal surface, are condensed to form Si-O-Si siloxane chains. Crosslinking and branching produce dense networks which limit electrolyte access to the adjacent metal surface and thus form an effective barrier against corrosive attack.

 DE GREAVE and colleagues (Progress in Organic Coatings 59, 224-229. 2007) investigated the influence of curing bis-1,2- (triethoxysilyl) ethane (BTSE) on aluminum substrate (AA1050 - 99.5%) A1) using complementary techniques such as ellipsometry (ES), electrochemical impedance spectroscopy (EIS), exploratory differential calorimetry (DSC) and combined thermogravimetric analysis with mass spectrometry (TGA-MS). Silane films were deposited on aluminum by immersion in acidic pH methanolic solution. The temperature range in which cure can occur extends from 100 to 300 ° C, with maximum rates being obtained at 200 ° C. Infrared spectra showed an increase in the absorption band relative to the Si-O-Si group, while the band relative to the Si-OH group has its absorption reduced by the curing process. The initially formed silane film is densified and shrunk by curing as shown by ellipsometry data, resulting in barrier properties according to electrochemical impedance spectroscopy data.

Bis-1,2- (triethoxysilyl) ethane (BTSE) is the most common compound found in various commercial silane mixtures for thin film deposition. However, the BTSE molecule is poorly soluble in water, Because of this, the use of BTSE methanolic solutions was very common. From the industrial point of view these solutions have been discontinued in view of the toxicity arising from the high content of methanol and silane itself. Thus, aqueous BTSE solutions were commercially supplied and employed within the industry. However, its stability is limited, since the addition of excess water may lead to the early hydrolysis of the ethoxy groups, generating undesirable competition between the reaction of the silanol groups with the metal and the condensation reaction. The formation of long chain species as a result of the condensation reaction reduces reactivity with the metal surface.

Compared to BTSE methanolic solution the aqueous solution has less monomer and more condensed polymers, which affects the structure of the silane layer deposited on the metal. In the uncured condition, the silane layer from the aqueous solution already has polymerized species. Electron microscopy images revealed similarities between the two silane films, but the properties of the layers may be affected otherwise. The cure kinetics of these films will be different, since crosslinking has already begun in advance in the aqueous solution and thus larger species can combine, which is important regarding the barrier property of the film. Therefore, after a short curing time the barrier performance of the BTSE aqueous solution film is superior. Indeed, the results of electrochemical impedance spectroscopy reveal this behavior {DE GREAVE et al., Progress in Organic Coatings 63, 38-42. 2008).

It is also noteworthy that another important factor regarding the morphology of the formed film is the concentration of silane solution. The more diluted the silane solution, the less compact the layers of deposited film (DE GREAVE et al., Progress in Organic Coatings 63, 38-42. 2008).

 FRIGNANI and colleagues (Corrosion Science 48, 2258-2273. 2006) studied the inhibitory effects of silane compounds (with 3 or 8 or 18 long aliphatic carbon atoms) for corrosion of AA7075 aluminum alloy in solutions. of 0. IN Na 2 SO 4 or NaCl compared to those provided by BTSE. Polarization curves were recorded using the electrochemical impedance spectroscopy technique.

The aluminum was previously sanded, washed with distilled water, degreased with acetone, activated in basic medium and washed again before immersion in methanolic solution of the organo silanes. Curing was performed at 100 ° C for 1 hour (FRIGNANI et al, Corrosion Science 48, 2258-2273. 2006).

[00019] The presence of a long aliphatic chain in the silane molecule markedly increases the protective action of these films. The longer the alkyl chain, the greater the action. This improvement is related to the increased film thickness, which causes a noticeable impediment to penetration of aggressive aqueous solutions. Such layers completely cover the aluminum surface, although not uniformly. While all layers silânicas inhibit the cathodic reaction, only the organo-silane chain C _i8 can inhibit anodic reaction, even in the presence of chlorides (Frignani et al, Corrosion Science 48, 2258-2273. 2006).

[00020] CORREA-BORROEL et al. (Journal of Applied Electrochemistry 39, 2385-2395. 2009) evaluated the effect of alkyl radical size of non-functional organo silanes on AA2024 deposited films (92.5% Al) and with organic coating adjacent polypyrrole. The organosilanes studied were propyl (C3), octyl (C8) and octadecyl (C18) trimethoxysilane. The silane film was deposited by immersion in methanolic solution and cured at 80 ° C for 1 hour. Polypyrrole coating was performed by electroplating. The aluminum surface has been previously sanded and degreased. Anti-corrosion protection was observed to be only limited and decays when subjected to highly corrosive environments such as salt spray booths for extended periods. The combination of silane film and polypyrrole coating produces a structure that provides better protection over time. The best performance is achieved with the deposition of polypyrrole on silanes due to the excellent bond between the adsorbed silane on the aluminum surface and the polypyrrole film. Of the three organosilanes used, the one with the lowest chain has the best performance. When long chain organo silanes are used, the polypyrrole film becomes independent due to the lower interaction between the layers. Electrochemical impedance spectroscopy and morphological studies of the layers also revealed greater adhesion and less deterioration of polypyrrole deposits in silane layers.

COMYN is a contributor {International Journal of Adhesion & Adhesives 20, 77-82. 2000) compared the pretreatment of aluminum joints with glycidoxypropyltrimethoxysilane (GPTMS), 3-aminopropyltrimethoxysilane (APES) and phosphoric acid anodization (PAA). The aluminum used was AA1050 (99.5% Al), which was degreased with methyl ethyl ketone (MEK). Silane films were deposited by immersion in 2% aqueous GPTMS or APES solution and drying at room temperature. Anodizing with phosphoric acid was performed in a bath with phosphoric acid solution (10%). at 10V in a stainless steel tank that worked as a cathode and drying was performed at room temperature. After pretreatment, the amine-functionalized nitrile-copolymer-based copolymer sealant was applied.

 Both of the silanes chosen are functional, that is, they have groups capable of chemically reacting with the sealant, forming an interface with aluminum through covalent chemical bonds, since the silanols groups react with the metal surface and the epoxy group. GPTMS reacts with nitrile rubber amino groups, while APES amino groups react with epoxy resin. The use of both GPTMS and APES promoted an increase in adhesion strength, as observed for PAA. In addition, the resistance to fluids such as gasoline, water and water and antifreeze has been improved, ie the joints have retained their adhesion strength for up to 15 weeks of immersion in said fluids (COMYN et al. International Journal of Adhesion & Adhesives 20, 77-82, 2000).

 SETH et al. (Progress in Organic Coatings 58, 136-145. 2007) used bis [3- (triethoxysilyl) propyl] (tetra-sulfide) sulphide in conjunction with epoxy acrylate resins or new aca-epoxy polyurethane and Zinc phosphate within the concept of superprimers. All components of the formulation were mixed with high shear and deposited on AA2024-T3 aluminum surfaces. Curing was performed at room temperature for 14 days.

EPI 097259, owned by the University of Cincinnati (2005), addresses the use of silane polysulfide solutions to obtain protective films deposited on a wide range of metal substrates, including zinc, copper, aluminum and their alloys. THE The solvent of these solutions is a mixture of alcohol and water, the pH around 4 and the silane concentration in the range of 1 to 5%. Film deposition may be by immersion, spray or other conventional technique. The results obtained after immersion in NaCl solution for 100h were exceptional for substrates coated with silane films.

 Patent US6827981, also owned by the University of Cincinnati, discloses a mixture of functional organo silanes, more specifically vinyl silane and bis-silyl amino silane, for the deposition of protective films on zinc substrates and their leagues. These films do not need to be removed for subsequent applications of paints, adhesives and other polymeric layers, rather they act to favor the anchoring of these coatings. The solutions containing the functional organosilanes are preferably aqueous, but also contain organic solvents of the alcohol class to increase the solubility of hydrolysed silanes. The pH of the solution may range from 4 to 10, depending on the ratio of vinyl silane to bis-silyl amino silane, preferably around 4. The metal substrate should be solvent cleaned or chemically activated in alkaline medium. Film deposition may be by immersion, spray or any other technique and drying is performed at 90 ° C for 1 hour. The protection mechanism is the establishment of a dense polymeric network formed by the inter and intra silane reaction, as well as an effective anchorage on the metal surface due to the action of Si-OH silanols, which chemically bind to the Si-OM metal surface. .

EP 1153089, filed by Chemetall PLC (2007), follows the same line as the University of Cincinnati patent, combining vinyl silane with bis silyl silane in aqueous / alcoholic solutions. The ratio of vinyl silane to bis-silyl silane around 1: 2 and pH in the range from 3 to 6. The range of metallic substrates was expanded with the insertion of steel, iron and aluminum. Deposition was also performed by methods known as dipping or spraying. Drying is performed at 40 to 180 ° C for sufficient time. The proposed mechanism is exactly the same as in the previous patent, that is, the creation of a dense polymer network by the reaction between the silanes, with the affinity of bis-silyl silane for the metal surface being higher compared to vinyl silane.

 Previously, Chemetall PLC (2002) had filed US6361592 in the same manner as described above, but using urea silane instead of vinyl silane combined with bis silosilane. The other variables were very similar if not the same, except for the ratio between urea-silane and bis-silyl silane which was around 1: 10.

Also in the silane blending line, Shin-Etsu Chemical Co. (2006) filed EPI 705231, which addresses the development of aqueous solutions of amino-silane-bisilyl-silane mixing for film production. via immersion preferably in various steel substrates. Solution pH and film drying conditions are identical to those reported in other patents.

BEXELL and OLSSON (Surface and Interface Analysis 35, 880-887. 2003) evaluated the use of functional and non-functional organo-silane mixtures for the formation of films on aluminum, zinc and aluminum and zinc alloys. For this purpose ol, 2-bis (triethoxysilyl) ethane (BTSE) and mercaptopropilt imethoxysilane (MPS) were chosen. The deposition was performed by two-step immersion, the first being immersion in BTSE solution and the second in MPS solution, both containing methanol and water in the ratio 60%: 40%. The variables of this study were bath pH and metallic substrate composition. The surface of the metals was previously polished, degreased and activated in alkaline medium. After immersion the substrates were dried under inert atmosphere flow.

[Ò0030] ToF-SIMS (Flight Time SIMS or Static SIMS) analyzes revealed that BTSE was completely hydrolyzed, while MPS was only partially hydrolyzed. In addition, the presence of HSi _x O _y - negative ions indicates that the two silanes formed a highly crosslinked Si-O-Si bonded film. The two-step treatment resulted in a bilayer film, the upper one consisting primarily of MPS. However, the thickness of this bilayer film was lower than the film obtained by BTSE deposition only, suggesting that part of the BTSE is dissolved during the immersion step in the MPS solution in the two-step process. Finally, it was found that the MPS mercapto group was not oriented outside the molecule, which would be of interest for the deposition of a third layer of another organic substance (Surface and Interface Analysis 35, 880-887. 2003).

 Currently, bearings have their surfaces mechanically activated with oxide blasting, which increases the surface roughness, providing physical anchor points, as well as favoring the formation of an aluminum oxide layer, which in contact with Moisture from the air generates aluminum hydroxide, which contributes to the chemical anchoring of the poly (amide imide) coating which contains in its formulation a mixture of mono and bis silane.

However, the blasting has the disadvantage of accumulating tiny particles of oxide on the surface of the bearing, which result in premature failure of the part, as they impair the adhesion of the coating. Such surface dirt significantly impairs load capacity. Since the bearing is a hydrodynamic bearing, any dirt breaks the oil film leading to scratches and potential locking and rapid degradation of the part.

Detailed Description

 [00033] The present invention relates to the polymeric coated friction bearing bearing in internal combustion engines. Additionally, the present invention relates to the process for the production of polymeric coated bearing friction bearings in internal combustion engines.

 [00034] The present invention relates to the process of coating aluminum or bronze bearings consisting of a first step of degreasing the metal surface using water, neutral detergent and organic solvent; a second step of basic activation of the bearing surface with aqueous sodium hydroxide solution; a third stage of pretreatment of the metal surface with hydroalcoholic solutions of mono and bifunctional silanes, aiming at the formation of a polysiloxane film with the anchoring function of the polymeric coating, subsequently applied to the bronzine surface; a fourth step of condensation of silanes for polysiloxane film formation; a fifth step of applying the polymeric coating comprising poly (amide imide), poly (tetrafluoroethylene) and aluminum flakes; and a sixth heat curing step of the polymeric coating applied to the bearing. The composition of mono and bifunctional silane hydroalcoholic solutions has also been developed in this invention, as well as the curing time and temperature conditions for polysiloxane film formation.

Bronzes are produced by the process of casting a bronze alloy on a steel strip or by rolling together (clamping) between one aluminum alloy strip and another steel strip, subsequent stamping and finishing machining to the curved final shape.

 Prior to pretreatment with organo-silane hydro-alcoholic solutions surface cleaning is required in order to remove grease from the metal surface, ensuring access to the reagents involved in the basic attack and pre-treatment with hydro-alcoholic solution of organo silanes on the surface of aluminum or bronze.

Surface cleaning consists of washing the bronzin in three steps:

 (i) washing with distilled water;

 (ii) Washing with neutral detergent;

 (iii) Wash with organic solvent (acetone or methylene chloride) in an ultrasonic bath for 10 min.

 After cleaning for fat removal a basic activation with 0.5M aqueous sodium hydroxide solution is made. This activation is accomplished by soaking the bronzine in an aqueous sodium hydroxide solution bath having a molar concentration between 0.05 and 1M, more preferably 0.5M, for up to 15 minutes, more preferably 5 minutes. The bronzine is then rinsed thoroughly with distilled water and blown dry. This activation has the function of generating hydroxyl groups on the aluminum surface, capable of chemically reacting with the organo silanes via hydrolysis mechanism.

Thereafter, the chemically activated aluminum or bronze bronzes are immersed in a bath with hydroalcoholic organo silanes solution at room temperature for up to 5 minutes, more preferably 2 minutes. The solvent pair of the hydroalcoholic solution is water is an hydrocarbon chain alcohol of up to 4 carbons, more preferably 2 carbons, and the water / alcohol ratio may range from 10% / 90% to 90% / 10%, more preferably 50% / 50%. This bath should be kept under constant agitation. The organo silanes used may be mono silanes, bis silanes or a mixture of both, being hybrid molecules containing hydroxyl groups or functional organic groups such as methoxy and ethoxy, bonded to the silicon atom and other functional groups besides already cited highlighting chlorine, amine, sulfur and epoxide.

The concentration of the organo silane or the organo silane mixture may range from 4% to 8% by volume in the hydroalcoholic solution, more preferably 4%. Once prepared, the organo-silane hydroalcoholic solution should remain under gentle and constant stirring for up to 60 minutes, more preferably 30 minutes, before starting to soak the bronzines in order to hydrolyze the alkoxy groups with the formation of the groups. hydroxyl, which are responsible for the chemical interaction with the bronzine metal surface (aluminum or bronze) and later for the formation of the polysiloxane film during curing.

 The hydroalcoholic immersion bath may contain only a monosilane or a mixture of monosilanes or a mixture of mono and bis silanes. In admixture of organo silanes, whether mono or bis silanes, may vary from 95% / 5% to 80% / 20% by volume. The soaking of the bearings is performed at room temperature for up to 6 minutes, more preferably 2 minutes.

Following the immersion in hydroalcoholic solution of the organo silanes the bronzines are dried with an air blower, following to the curing step in an oven heated by electric resistances or infrared lamps at a temperature of 80 to 120 ° C, plus preferably 100 ° C. The healing time is Depending on the temperature and heat source of the oven, when this is electrical resistance the curing period may vary up to 120 minutes and when this is medium wavelength IR lamp the curing period may vary up to 30 minutes so that it occurs. the condensation of silanols with the formation of polysiloxane film.

Once the polysiloxane film is formed, the polymeric coating composed of the mixture poly (amide imide), poly (tetrafluoroethylene) and aluminum in solvent of N-ethyl pyrrolidone is sprayed to the bronzine on the polysiloxane layer with thickness between 6 and 20μιτι, more specifically 12μιτι. Finally, said coating applied to the aluminum or bronze bearing is cured in a heated oven with electric resistors or infrared lamps at a temperature of 160 ° C for up to 120 minutes.

 The invention described above will be further illustrated by the following examples and the appended claims.

 Examples

 Example 1: Use of γ-glidoxypropyl trimethoxy silane (GPTES) as precursor of polysiloxane film

 Aluminum bronzes were cleaned in three steps, namely: (i) washing with distilled water; (ii) washing with neutral detergent; (iii) washing with methylene chloride in an ultrasonic bath for 10 minutes.

After properly degreasing and drying, the bearings were chemically activated by soaking in 0.5M sodium hydroxide solution for 5 minutes and then washed with distilled water.

After drying, with the aid of a cold air dryer, the bearings were immersed for 2 minutes in GPTES solution in a 1: 1 ethanol / water mixture with 4% (v / v) organo-silane concentration. Then the bearings They were dried with the aid of a cold air dryer and placed in a conventional oven (heat source: electrical resistance) heated at 100 ° C for 30 minutes to form the polysiloxane film.

com espessura de 12 μηι. Por fim, o referido revestimento aplicado na bronzina de alumínio foi curado em forno convencional (fonte de calor: resistência elétrica) a 160°C por 120 minutos. Then, onto the polysiloxane film formed was spray deposited a polymeric coating composed of the mixture poly (amide imide), poly (tetrafluoroethylene) and aluminum in solvent of

with a thickness of 12 μηι. Finally, said coating applied to the aluminum bearing was cured in a conventional oven (heat source: electrical resistance) at 160 ° C for 120 minutes.

The adhesion of the set formed by the polysiloxane film and the polymeric coating to the aluminum bearing was evaluated according to NBR 11003/1990 - Paints - Determination of adhesions. All tested bearings had adhesions classified as Gr ₀ , ie no area of detached film.

 Example 2: Use of the mixture of (3-aminopropyl) triethoxy silane (APTES) with bis- (γ-trimethoxysilylpropyl) amine (BTSPA) as precursor of polysiloxane film

 Aluminum bronzes were cleaned in three steps, namely: (i) washing with distilled water; (ii) washing with neutral detergent; (iii) washing with methylene chloride in an ultrasonic bath for 10 minutes.

After properly degreasing and drying, the bearings were chemically activated by soaking in 0.5M sodium hydroxide solution for 5 minutes and then washed with distilled water.

After drying with the aid of a cold air dryer, the bearings were immersed for 2 minutes in a 9: 1 APTES / BTSPA mixture solution in a 1: 1 ethanol / water mixture with a 4% (v / v) organo-silane concentration. v). Then the bearings were dried with the aid of a cold air dryer and conditioned in a conventional oven (heat source: electrical resistance) heated at 100 ° C for 30 minutes for the formation of polysiloxane film.

Then, onto the formed polysiloxane film, a polymeric coating composed of the mixture poly (amide imide), poly (tetrafluoroethylene) and aluminum in a solvent thickness of N-ethylpyrolidone was deposited by spray. 12 μιτη. Finally, said coating applied to the aluminum bearing was cured in a conventional oven (heat source: electrical resistance) at 160 ° C for 120 minutes.

The adhesion of the set formed by the polysiloxane film and the polymeric coating to the aluminum bearing was evaluated according to NBR 1 1003/1990 - Paints - Determination of adhesions. All tested bearings had adhesions classified as Gr ₀ , ie no area of detached film.

 Example 3: Use of the mixture γ-glidoxypropyl trimethoxy silane (GPTES) with tetraethoxy silane (TEOS) as a precursor of polysiloxane film

Aluminum bronzines were cleaned in three steps, namely: (i) washing with distilled water; (ii) washing with neutral detergent; (iii) washing with methylene chloride in an ultrasonic bath for 10 minutes.

After properly degreasing and drying, the bearings were chemically activated by soaking in 0.5M sodium hydroxide solution for 5 minutes and then washed with distilled water.

After drying, with the aid of a cold air dryer, the bearings were immersed for 2 minutes in a GPTES / TEOS 9: 1 mixture solution in a 1: 1 ethanol / water mixture with 4% organo-silane concentration. (v / v). Afterwards, the bearings were dried with the aid of a cold air dryer and placed in a conventional oven (heat source: electrical resistance) heated at 100 ° C for 30 minutes for the formation of polysiloxane.

 Subsequently, on the formed polysiloxane film, a polymeric coating composed of the mixture poly (amide imide), poly (tetrafluoroethylene) and aluminum in a 12 μπι thick N-ethyl pyrrolidone solvent was sprayed. Finally, said coating applied to the aluminum bearing was cured in a conventional oven (heat source: electrical resistance) at 160 ° C for 120 minutes.

[00059] - The adhesion of the set formed by the polysiloxane film and the polymeric coating to the aluminum bearing was evaluated according to NBR 1 1003/1990 - Paints - Determination of adhesions. All tested bearings had adhesions classified as Gr ₀ , ie no area of detached film.

Claims

 1. A polymeric coated bronzine comprising mono- and bifunctional silanes, poly (amideimide), poly (tetrafluoroethylene) and aluminum flakes.  Polymer-coated bronzine according to claim 1, characterized in that mono and bifunctional silanes are present in hydroalcoholic solutions during application, included in the group containing monofunctional γ-glidoxy-propyl trimethoxysilane silanes, (3-aminopropyl ) triethoxy silane, N- [3- (trimethoxy silyl) propyl] ethylenediamine, tetraethoxy silane, ethyl triethoxy silane, chloro methyl triethoxy silane, vinyl methyl diethoxysilane, (3 methacryloxypropyl (- trimethoxy silane, but not restrictive (3-mercaptopropyl) triethoxy silane, and bifunctional silanes comprised of the group consisting of bis- (γ-trimethoxysilylpropyl) amine (BTSPA), bis (triethoxysilylpropyl) tetrasulfide bis (triethoxysilylpropyl), but not restrictive thereto.  Bronzine according to claims 1 and 2, characterized in that the silanes are located at the interface of the metal part with the polymeric coating.  Bronzine according to claims 1 and 2, characterized in that the silanes are located both at the interface of the metal part with the polymeric coating and within the composition of the polymeric coating.  A process for producing a polymeric coated bronzine comprising the following steps: i. cleaning the bronzine metal surface with water solution and neutral detergent and organic solvent, preferably in an ultrasound bath;  ii. activating the metal surface by soaking the bronzine in aqueous sodium hydroxide solution, preferably with a molar concentration between 0.05 and 1 M, more preferably 0.5 M, for up to 15 minutes, more preferably 5 minutes;  iii. abundant rinse of bronzine in water; iv. drying the bearing in forced air;  v. immersion of the chemically activated bronzines in a bath with organo silane hydroalcoholic solution, comprising water and an hydrocarbon chain alcohol of up to 4 carbons, more preferably 2 carbons, and a water / alcohol volume ratio ranging from 10% / 90% up to 90% / 10%, more preferably 50% / 50%, organo silane or organo silane mixture at a concentration of 4% to 8% (v / v) at room temperature for up to 5 minutes.  saw. keeping the organo silane hydroalcoholic solution under gentle and constant stirring before starting to soak the bronzines until hydrolysis of the alkoxy groups with the formation of the hydroxyl groups occurs, preferably for 30 min;  vii. drying the bearings with forced air;  viii. curing the organo silane at 80 ° C to 120 ° C for up to 120 minutes, more preferably 30 minutes in an electric resistance heating oven and 15 minutes in an oven heated by medium wavelength infrared lamps;  ix. condensation of the silanol groups with the formation of polysiloxane film; x. application of the polymeric coating comprising poly (amide imide), poly (tetrafluoroethylene) and aluminum in N-ethyl pyrrolidone solvent by spraying on the polysiloxane layer, between 6 and 20μιη, more specifically 8 to 12μιη.  xi curing of the polymeric coating applied to the bearing from 120 ° C to 180 ° C for up to 120 minutes in an oven with electric resistance heating or in an oven heated by medium wavelength infrared lamps;  Process for the production of polymeric coated bronzine according to claim 3, characterized by immersion in a hydro-colic solution containing a monosilane or a mixture of monosilanes or a mixture of mono and bis silanes.  Process for producing a polymeric coated bronzine according to claim 4, characterized in that the mixture between monofunctional or monofunctional / bifunctional organo silanes ranges from 95% / 5% to 80% / 20%.