AU2013203296A1 - Corrosion resistant bushing - Google Patents

Abstract

A method of forming a corrosion resistant bushing includes bonding a sliding layer to a first surface of a load bearing substrate to form a laminate sheet and cutting a blank from the laminate sheet. The laminate sheet includes an exposed surface corresponding to a second surface of the load bearing substrate. The blank includes cut edges having a load bearing substrate portion, The method further includes forming a semi -finished bushing from the blank, and applying a corrosion resistant coating to the exposed surface and the load bearing substrate portion of the cut edges to form the corrosion resistant bushing.

Description

AUSTRALIA PATENTS ACT 1990 REGULATION 3.2 Name of Applicant: SAINT-GOBAIN PERFORMANCE PLASTICS PAMPUS GMBH Actual Inventor/s: Parag Natu Address for Service; E. F. WELLINGTON & CO, Patent and Trade Mark Attorneys, 312 St. Kilda Road, Melboume, Southbank, Victoria 3006. Invention, Title: "CORRISION RESISTANT BUSHING" The following statement is a full description of this invention including the best method of performing it known to us, Ihis application is a 'divisional' application derived from Australian Patent Application No. 2010288476 (International Application No. PCT/EP20 1/062544 : WO 201 1023794), claiming priority of US Application No. 12/549713, the entire text of which are hereby incorporated herein by reference FIELD OF THE DISCLOSURE This disclosure, in general, relates to corrosion resistant bushings. BACKGROUND Sliding bearing composite materials consisting of a load bearing substrate and a sliding layer overlay are generally known, The load bearing substrate and the sliding layer are usually connected by laminating using a suitable adhesive. The sing bearig compose materials can be used to form maintenance free bushing used, for example by be automotive industry. These maintenancefree bushings can be used for door, hoodl, and engine conpartment hinges, seats, steering columns, flywheel, balancer shaft bearings, etc. Additionally, maintenance free bushings formed from the sliding bearing composite materials can also be used in non-automotive applications. There isan ongoing need for Unproved maintenance free bushings that have a longer maintenance free ?lfetime and improved corrosion resistance; SUMMARY In an embodiment, a method of forming a corrosion resistant bushing can include cutting a blank from a laminate sheet including a sliding layer bonded to a first surface of a load bearing substrate. The blank can have cut edges including a load bearing substrate portion and an exposed major surface of the load bearing substrate. The method can further include forming a semi finished bushing from the blank, and applying a corrosion resistant coating to the exposed surface and the load bearing substrate portion of the cut edges to fortn the corrosion resistant bushing. In another enmbodiment, a bushing can include a load bearing substrate, The load bearing substrate can have a first major surface a second major surface, and edges, A sliding layer can be bonded to the first surface, and a corrosion resistant layer can be bonded to the second surface and can extend to cover the edges of the load bearing substrate. In et another embodiment, a hushing can include a load bearing substate. The load bearing substrate can have a first major surface and a second major sudace A sliding layer can be bonded to the first surface, and a corrosion resistant layer can be bonded to the second

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surface. Further, the bushing can have a Corrosion Resistance Rating of at least about 120 hours BRIEF DESCRIPTION OF THE DRAWINGS The present disclosure may be be better understood, and its numerous features and advantages made apparent those skilled in the ar by referencing the accompanying drawings FIGs .1 and 2 are illustrations of the layer structure of exemplary corrosion resistant bushings F1G 3 is an illustration of various embodiment of bushing, FIGs. 4, 5. and 6 are illustrations of exemplary hinges, FIG 7 is an illustration of an exemplary bicycle headset. FIG 8 is a view of the corrosion resistant bushing. FIG, 9 is an alternate view of the corrosion resistant bushing, FIG, 10 is a close-up view of region 802 of FIG. 8 showing the cut edges of the corrosion resistant bushing. The use of the same reference symbdls in different drawings indicates similar or identical items DETAILED DESCRIPTION FIG. 1 shows a cross section illustrating the various layers of the corrosion resistant bushing, generally designated 100, Bushing 100 can include a load bearing substrate 102, The load bearing substrate 102 can be a metallic support layer. The metallic support layer can include a metal or metal alloy such as steel including carbon steel, spring steel, and the like, iron, aluminum, zinc, copper, magnesium. or any combination thereof. In a particular embodiment, the load bearing substrate 102 can be a metal (including metal alloys), such as ferrous alloys. The load bearing substrate 102 may be coated with temporary corrosion protection layers 104 and 106 to prevent corrosion of the load bearing substrate prior to processing, Additionally, temporary corrosion protection layer 10$ can be applied over top of layer 104. Each of layers 104, 106, and 108 can have a thickness of between about I micron to about 50 microns, such as between about 7 microns and abom 15 microns. Layers 104 and 106 can include a phosphate of zinc, iron, manganese, or any combination thereof, Additionally, the layers can be a nano-ceramic layer. Further, layers 104 and 106 can include functional sianes, nano-scaled silane based primers, hydrolyzed silanes, organosilane adhesion promoters, solvent/water based silane primers, chlorinated polyoletins, passivated surfaces, comumercially available zinc (mechanical/gaivanic) or zinc-nickel coatings, or any combination there. Laver 108 can include functional silanes, nano-scaled lane based primers, hydrolysed silanes, organosilane adhesion promoters, solvent/water based silane primers. Temporary corrosion protection layers 104, 106, and 108 can be removed or retained during processing. A sliding layer 110 can be applied to the load bearing substrate 102 with an adhesive layer 112. The sliding layer 110 can include a polymer. Examples of polymers that can be used in sliding layer I 10 include polytetrafluoroethylene (P E) fluorinated ethylene propylene (FEP), polyvinylidenfluoride (PVDF), polychlorotrifPuoroethylene (P IE), ethylene chlorotrifluoroethytene (ECT'F), perfiuoroaikoxypolymer, polyacetal, pulybutylene terephthalate, polyimnide, polyetherinmde, polyetheretherketone (PEEK), polyethylene, polystdfone, poly amide, polyphenylene oxide, polvphenylene sulfide (PPS), polyurethane. polyester, or any combination thereof. Additionally, sliding layer 110 can include fillers, such as a friction reducing filler. Examples of fillers that can be used in the sliding layer 110 include glass fibers' carbon fibers, silicon, graphite, PEEK, molybdenum disullide, aromatic polyester, carbon particles, bronze, fltoropolymer, thermoplastic fillers, silicon carbide, aluminum oxide., polyamidimide (PAl), PPS, polyphenylene sulfone (PPS02), liquid crystal polymers (LCP), aromatic polyesters (Econol j and mineral particles such as wollastonite and bariumsulfate, or any combination thereof. Fillers can be in the form of beads, fibers, powder, mesh, or any combination thereof In an embodiment, the sliding layer may include a woven mesh or an expanded metal grid. The woven mesh or expanded metal grid can include a metal or metal alloy such as aluminum, steel, stainless steel, bronze, or the like. Alternatively, the woven mesh can be a woven polymer mesh. In an alternate embodiment, the sliding layer may not include a mesh or grid. in another alternate embodiment shown in FIG. 2, the woven mesh or expanded metal grid 120 may be embedded between two adhesive layers 112A and 11213. Returning to FIG. 1, adhesive layer 112 can be a hot melt adhesive, Examples of adhesive that can be used in adhesive layer 112 include fluoropolymers, an epoxy resins, a polyimide resins, a polyether/polyamide copolymers, ethylene vinyl acetates, Ethylene tetrafluoroethylene (ETFE), EFE copolymrer, perfluoroalkoxy (PFA), or any combination thereof, Additionally, the adhesive layer 1.12 can include at least one functional group -3selected from -C,=O -C-R, <'OC, OH -C T OOR, -CF=C-OR, o any combination thereof, where R is a cyclic or linear organic group containing between I and 20 carbon atoms, Additionally, the adhesive layer I112 can include a copolymer, In an embodiment, the hot melt adhesive can have a melting temperature of not greater than about 250>C, such as not greater than about 220C. In another embodiment, the adhesive layer 112 mIav break down above about 200VC, such as above about 220"C. In further embodiments, the melting temperature of the hot melt adhesive can be higher than 250(C, even higher than 300C, On an opposing surface of the load bearing substrate 102 from sliding layer 110, a corrosion resistant coaling 114 can be applied. The corrosion resistant coating 114 can have a thickness of between about 1 micron and about 50 microns, such as between about 5 microns and about 20 microns such as between about 7 microns and 15 microns. The corrosion resistant coating can include an adhesion promoter layer 116 and an epoxy layer I 18. The adhesion promoter layer 116 can include a phosphate of zine, iron, manganese, tin, or any combination thereof. Additionally, the adhesion promoter layer 116 can be nano-ceramic layer. The adhesion promoter layer 116 can include functional silanes, mmo-scaled silane based layers, hydoly zed silanes, organosilane adhesion promoters, solvent/water based silane primers, chlorinated polyolefins, passivated surfaces, commercially available zinc (mechanical / gal vanic) or Zinc-Nickel coatings, or any combination thereof, The epoxy layer I 18 can he a thermal cured epoxy. a UJV cured epoxy, an WiR cured epoxy, an electron beam cured epoxy, a radiation cured epoxy, or an air cured epoxy, Further, the epoxy resin can include polyglycidylether, digycidylether, bisphenol A, bisphenol F, oxirane, oxacyclopropane, ethylenoxide, 1,2-epoxypropane, 2-methyloxirane, 9,10-epoxy-9, 10-dihydroanthracene, or any combination there'.of The epoxy resin can include synthetic resin modified epoxies based on phenolic resins, urea resins, melamine resins, benroguanamine with formaldehyde, or any combination thereof By way of example, epoxies can include GxHYXzhk C CxHyXrAuC X mono epoxoide CxHyXzA~ CHyXzAu C - C CxHyXzAu- C -C GxHyXzA NCHuXA. x H XAu Cxzytz, bis epoxide -4linear tris epoxide 0 5 HyX 7 Au 0 0 0 if %, CxHyXzAe C - C 0xHyXzAu C C - CxHvXzAu C C CX HX A7A OxHyXzk CrXHyXzAr CHXACxHvXzA CxvXzAv ranfled tris epoxide C-C C -A NCxHXzA B CXHYXzA C XzA > XA CHXzA CxQz~ N,' 11xY~u'xHvXzAu o n C C c CxHyXzAu C0H A3 CMQxHN~z combination thereof wherein CxHIXzAu £s a linear or raified saiuated or unsaturated carbon chain wit optionally halogen atoms X substtutig hydrogen atoms. andoptionally where atoms like nitrogen phosphorous, boron, etc; are present and B is one o carbon, nitrogen, oxygen, phosphorous, boron, sulfur, etc. The epoxy resin can further include a hardening agent. The hardening agent can include amines, acid anhydrides, phenol novolac hardeners such as phenol novofac poly[N{4 hydroxyphenyl)maleimide] (PPMI), resole phenol fornaldehydes, fatty anne compounds, polycarbonic anhydrides, polyacrylate, isocyanates, encapsulated polyisocyanates, boron trifluoride amine complexes, chromic-hased gardeners, polyanides, or any combination thereof, Generally, acid anhydrides can conform to the formula R-C=0-)&C0-R' where R can be C 5 HyXzAu as described above. Amines can include aliphatic amines such as monoethyamine, diethylenetrianine, triethylenetetraamine, and the like, alicyclic amines, aromatic amines such as cyclic aliphatic anmnes, cyclo atiphatic anines, amidoamines polyamides, dicyandiamides, irmidazole derivatives, and the like, or any combination thereof. Generally, amines can be primary amines, secondary amnines, or tertiary amines conforming to the fornula RI RR3N where R can be CxHyXzAu as described above, In an embodiment, the epoxy layer I IS can include fillers to improve the conductivity, such as carbon fillers, carbon fibers, carbon particles, graphite, metallic fillers such as bronze, aluminum, and other metals and their alloys, metal oxide fillers, metal coated carbon fillers, metal coated polymer fillers, or any combination thereof, The conductive fillers can allow current to pass through the epoxy coating and can increase the Conductivity of Qhe coated bushing as compared to a coated bushing without conductive fillers. -5,- In an embodiment, an epoxy layer can increase the corrosion resistance of the bushing. For example, an epctxy layer, such as epoxy layer 11 8. can substantially prevent corrosie elements, such as water, salts, and the like, from contacting the load bearing substrate, thereby inhibiting chemical corrosion of the load bearing substrate, Additionally, the epoxy layer can inhibit galvanic corrosion of either the housing or the load bearing substrate by preventing contact between dissimilar metals For example, placing an aluminum bushing without the epoxy layer within a magnesium housing can cause the magnesium to oxidize, However, an epoxy layer, such as epoxy layer ItS, can prevent the aluminum substrate from contacting the magnesium housing and inhibit corrosion due to a galvanic reaction. Turning to the method of forming the bushing, the sliding layer can be glued to the load bearing substrate using a melt adhesive to form a laminate sheet The laminate sheet can be cut into strips or blanks that can be formed into the bushing. Cutting the laminate heet can create cut edges including an exposed portion of the load bearing substrate, The blank can be formed into the bushing, suet as by ruling and flanging the laminate to fomn a semi finished bushing ofdesired shape FIGs, 3A through 3F illustrates a number of bushing shapes that can be formed front the blanks, FIG, 3A illustrates a cylindrical bushing that can be formed by rolling. FIG, 3B illustrates a flanged bushing that can be formed by rolling and flanging. FIG. 3C illustrates a flanged bushing having a tapered cylindrical portion that can be Formed by rolling a tapered portion and flanging an end. FIG, 31) illustrates a flanged bushing mounted in a housing with a shaft pin mounted through the flanged bushing. FIG. 3F illustrates a two-sided flanged bushing mounted in a housing with a shaft pin mounted through the two-sided flanged bushing, FIG. 3F illustrates an L, type bushing that can be formed using a stamping and cold deep drawing process, rather than rolling and flanking. After shaping the semi finished bushing, the semi-finished bushing may be cleaned to remove any lubricants and oils used in the forming and shaping process. Additionally, cleaning can prepare the exposed surface of the load bearing substrate for the application of thle corrsio reisan coaing lenig may i ncludeI cei w ncal Cleaning wi th solents and/or mechanical. cleaning, such as ultrasonic cleaning. In an embodiment, an adhesion promoter layen such adhesion promoter layer 116. can be applied to the exposed surfaces of the load bearing substrate. The adhesion promoter layer can include a phosphate of zinc, iron manganese tin, or any combination thereof, The adhesion promoter layer may be applied as a nino-ceramic layer The adhesion promoter layer 116 can include funcdonal silanes, nano-scaled silane based layers, hydrolyzed silanes, -6organosilane adhesion promoters, solvent/water based silane primers, chlorinated poyolefir, passivated surfaces, commnercially available zinc (mechanical / galvanic) or Zinc -Nickel coatings, or any combination thereof. The adhesion promoter layer can be applied by spray coatin C-coting dip spin coating, electrostatic coating., flow coating, roll coating, kmfe coating, Coil catng, or the like. Further, application of the corrosion rsistantlayer can include applying an epoxy coating The epoxy can be a two-component epoxy or a single cmponent epoxy. Advantageously, a single component epoxy can have a longer working life. The working life can be the amount of time from preparing the epoxy until the epoxy can no longer be applied as a coating. For example single component epoxy am have a working life of months compared to a working life of a two-component epo<xy of a few hours In an embodimnt, the epoxy layer can be applied by spray coating, coating, dip spin coating, electrostatic coating, flow coattng, roll coating, knife coating, coil coating, or the like. Additionally, the epoxy layer can be cured, such as by thermal curing, UV curing, IR curing, electron beam curing, irradiation curing, or any combination thereof Preferably, the curing can be accomplished without increasing the temperature of the componem above the breakdown temperature of any of the sliding layer, the adhesive layer, the woven tmesh, or the adhesion promoter layer. Accordingly, the epoxy may be cured below about 25TC, even below about 200"C. Preferably, the corrosion resistant coating, and particularly the epoxy layer, can be applied to cover the exposed edges of the load bearing substrate as well as the major surface not covered by the sliding layer, E-coaing and electrostatic coating can be particularly useful in applying the corrosion resistant coating layers to all exposed metallic surfaces without coating the non-conducting sliding layer, Further, it is preferable for the corrosion resistant coating to continuously cover the exposed surfaces of the load bearing substrate without cracks or voids. The continuous, conformal covering of the load bearing substrate can substantially prevent corrosive elements such as salts and water from contacting the load bearing substrate, In an embodiment, the bearing with such a corrosion resistant coating can have a significantly increased lifetime, and in particular, the bearing can have a Corrosion Resistance Rating of at least about 120 hours, such as at least about 168 hours, such as at least about 240 hours, even at least about 288 hours, In an alterate embodiment, the corrosion resistance layer can be applied at any point during the processing of the bushing, including before applying the sliding layer, prior to forming the blank but after applying the sliding layer, or between forming the blank and -7shaping the bushing FIG4 and 5 illustrate an exemplary hinge 400. such as an automotive door hinge. hood hinge engine compartment hinge, and the like. Hinge 400 can include an inner hinge pordon 402 and an outer hinge portion 40 Hinge portions 402 and 404 can be joined by rvets 406 and 408 and bushings 410 and 412 Bushings 410 and 412 can be corrosion resistant bushings, as previously described. FIG. 5 illustrates a cross section of hinge 400, showing rivet 408 and bushing 412 in more detail FIG, 6 illustrates another exemplary hinge 600, such as an automotive door lunge. hood hinge, engine compartment hinge, and the like. Hinge 600 can include a first hinge portion 602 and a second hinge portion 604 joined by a pin 606 and a bushing 608. Bushing 608 can be a corrosion resistant bushing as previously described. FG. 7 illustrates an exemplary headset 700 for a two-wheeled vehicle, such as a bicycle. A steering tube 702 can be inserted through a head tube 704. Bushings 706 and 708 can be placed between the steering nbe 702 and the head rube 704 to maintain alignment and prevent contact between the steering tube 702 and the head tube 704. Additionally, seals 710 and 712 can prevent contamination of the sliding surface of the hushing by dirt and other particulate matter. Examples A Corrosion Resistance Rating is determined according to the neutral salt spray test defined by ISO 9227:2006 "Corrosion tests in artificial atmospheres - salt spray tests" Second Edition published July 15, 2007. Generally, a test bushing is placed in a salt spray chamber and subjected to a spray of salt until at least 10% of the surfac is covered by iron rust. For example Comiparative Sample 1 is prepared by cutting a blank from an 'M' type laminate (M100GG-2022-B commercially available from Saint-Gobain Performance Plastics) and saigto fomthe -ifnse uhn. Tebak is shaped by rolling and flanging anshqang t-form tesemri-finished bushng. TeN to obtain the desired shape. The semi-finished product is galvanized with a layer of zine Passivation chemicals are applied to the zinc layer, and then a sealing layer is applied overtop the passivated zinc layer. The Corosion Resistance Rating of Comparative Sample J is determined to be 96 hours Sample 2 is prepared as Comparative Sample I except an epoxy layer is applied to the semi-finished bushing rather than the passivated and sealed zinc layer. The epoxy layer is applied using an coating process. Sample 3 is prepared as Sample I except a zinc phosphate layer is applied to the seni-finished bushing as an adhesion promoter layer prior to -8the epoxy layer. Sample 4 is prepared as Sample 3 except a galvanic zinc layer is used as the adhesion promoter layer. Sample 5 is prepared as Sample 3 except a mechanical zinc layer is used as an adhesion promoter layer. The Corrosion Resistance Ratings of Samples 2, 3, 4, and 5 are determined to be at least 120 hours, at least 120 hours, at least 300 hours, and at least 250 hours, respectively. FIGs. 8 and 9 show the finished bushing of Sample 2, FIG, 10 is a close up view of the edge region 802 of FG. 8. RG. 10 shows the conformal coating of the epoxy on the load bearing substrate portion of the cut edge of the laminate, as indicate at 1002.

Claims (12)

1. A method of forinn a cormRsion rekistant bushing, comprising: cutting a blank from the laminate sheet, the laminate sheet including a sliding layer overtop a load bearing substrate, the blank having cut edges including a load bearing substrate portion and an exposed major surface of the load bearing substrate; forcing a semti-fished bushing from the blank; and applying a corrosion resistant coating to the exposed major surface and the load bearing substrate portion of the cut edges to form the corrosion resistant bushing. 2, The method of claim I, further comprising bonding the sliding layer to a first surface of the load bearing substrate to form the laminate sheet. 3, The method of claim I wherein the corrosion resistant coating has a thickness of between about 5 microns and about 20 microns, preferably the thickness is between about 7 microns and about 15 microns.

4. The method of claim 1 wherein applying the corrosion resistant coating includes e-coating spray coating, dip spin coatinga e ostatic C , amating, rolcoating knife coating, coil coating, or aiiy combination thereof 5, The method of claim 1, wherein applying the corrosion resistant coating further includes applying an epoxy resin layer.

6. The method of claim 5 wherein the epoxy resin layer has a cure temperature below a degradation temperature of the laminate sheet

7. The method of claim 5, wherein the epoxy resin includes polyglyidylether, diglyridylether, bisphenol A, bisphenol F, oxirane, oxacyclopropaneethylenoxide, 1,2. -1 0- epoxypropane 2-methyloxirane 9,10-epoxy- Odihydroanrhracene, or any combination thereof

8. The method of clanin 7 wherein the epoxy resin further includes a hardening agent.

9. The method of claim 8. wherein the hardening agent is in an encapsulated non reactive frmi or the hardening agent includes an aliphatic amine) an alicyclic amine, an aromatic amine, or any combination thereof

10. The method of claim 5, wherein applying the corrosion resistant coating further includes curing the epoxy resin layer, preferably curing the epoxy resin includes thermal curing, UV curing, JR Curing, electron beam cuing, irradiation curin, or any combination thereof 11, The method of claim 5, wherein applying the corrosion resistant coating includes applying an adhesion promoter layer to the semi finished bushing.

12. The method of claim 11, wherein the adhesion promoter layer includes a phosphate of zine, iron. manganese tin, r any combination thereof 13, The method of claim 1, wherein bonding the sliding layer to the first sreace of the load bearing substrate includes applying a mch adhesive between the siding layer and the first surface.

14. The method of claim 13, wherein the melt adhesive includes a fluoropolyner, an epoxy resin, a polyimide resin, a polyetherfpolyanide copolymer, ethylene vinyl acetate, or any combination thereof

15. The method of clain 1, wherein the sliding layer includes a polymer. -1.1- 6. The method of claim 15, wherein thepolymer includes polytetrafluoroethylene, fluorinated ethylenepropylene, polyvinylidenfluoride, polychorotri fluoroethylene, ethylene chlorotrinuoroethylene, perfinoroalkoxypolymer; polyacetal. polybutylene terephthalate, polyiniide, polyetherimide, polyetheretherketone, polyethylene, polysulfone, polyamide, polyphenylene oxide, polyphenylene sulfide, polyurethane, polyester, or any combination thereof 17 The method of claim 15v, herein the sliding layer further includes a friction reducing filler.

18. The method of claim 17, wherein the friction reducing filler includes glass fibers, carbon fibers, silicon, graphite, polyetheretherkete, , molybdenum disulfide, aromatic polyester, carbon particles, bronze, 11uoropolymer, thermoplastic fillers, mineral tillers, or any combination thereof

19. The method of claim 1, wherein forming a semi-finished bushing including rolling and flanging. 2. Thenmethod of claim 1 further comprising washing the semi- finished hushing prior to applyving theC corroion ressant coatig. BA. 9080A