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AssigneeFederal-Mogul Wiesbaden GmbH
InventorsAchim Adam, Stefan Fuchsberger, Joachim Schluter
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The invention relates to a method for producing a metal base material that is provided with a sliding layer that has a thickness of more than 50 μm, said base material being used as a sliding element. According to the invention, the base material is coated with a paste of the sliding layer material that contains at least one high-temperature polymer in addition to a fluoropolymer, and the base material so coated is subjected to a thermal treatment. The paste applied to the base material contains as the fluoropolymer between 40% by volume and 75% by volume polytetrafluorethylene (PTFE) or polytetrafluorethylene (PTFE) with other fluoropolymers added and between 60% by volume and 25% by volume of the at least one high-temperature polymer, each based on the entire composition of the finished sliding layer. The high-temperature polymer used is selected from those high-temperature polymers whose melting point is not below 327° C., if they are mainly crystalline, or whose glass transition temperature is not below 327° C. if they are mainly amorphous.
A method of producing a roughened or porous metallic backing material provided with an overlay more than 50 μm thick, which is used as a sliding element, in which the backing material is coated with a paste of overlay material, which contains in addition to a fluoropolymer also at least one high temperature polymer, and then the backing material coated in this way is subjected to heat treatment, characterized in that a paste is applied to the backing material which comprises as fluoropolymer between 40 vol. % and 75 vol. % of polytetrafluoroethylene (PTFE) or polytetrafluoroethylene (PTFE) with additions of other fluoropolymers and between 60 vol. % and 25 vol. % of the at least one high temperature polymer, in each case relative to the total composition of the finished overlay, wherein high temperature polymers are used which have a melting point which is not less than 327° C., if they are predominantly crystalline, or a glass transition temperature of not less than 327° C., if they are predominantly amorphous.
A method according to one of the preceding claims, characterized in that a paste is applied to the backing material which comprises between 55 vol. % and 70 vol. % of polytetrafluoroethylene (PTFE) or polytetrafluoroethylene (PTFE) with additions of other fluoropolymers and between 45 vol. % and 30 vol. % of the at least one high temperature polymer, in each case relative to the total composition of the finished overlay.
A method according to one of the preceding claims, characterized in that the addition to the polytetrafluoroethylene (PTFE) is selected from the group comprising poly(tetrafluoroethylene-co-perfluorovinyl methyl ether (PFA), poly(tetrafluoroethylene-co-hexafluoropropylene (FEP), poly(hexafluoroisobutylene-covinylidene fluoride) (CM-1), poly(ethylene-alt-tetrafluoroethylene) (ETFE) and/or polyvinylidene fluoride (PVDF).
A method according to one of the preceding claims, characterized in that the proportion of the polytetrafluoroethylene is >40 vol. %.
A method according to one of the preceding claims, characterized in that a paste is used which comprises as high temperature polymer polyphenylene sulfone (PPSO2), polyetherether ketone, fully aromatic polyimides, fully aromatic polyesters and/or fully aromatic polyamides, preferably poly(p-phenylene terephthalamide) (PPTA), polyaramid (TWA) and/or poly(p-benzamide) (PBA).
A method according to one of the preceding claims, characterized in that the grain size of the plastics powder used is between 1 μm and the desired layer thickness.
A method according to one of the preceding claims, characterized in that the grain size of the plastics powder used is between 10% and 50% of the desired layer thickness.
A method according to one of the preceding claims, characterized in that the backing-material is coated with a paste which contains up to 35 vol. % of wear-reducing additions, relative to the total composition of the finished overlay, wherein the concentration of fluoropolymers should not fall below 40 vol. % relative to the total layer composition of the finished overlay.
A method according to one of the preceding claims, characterized in that a paste is applied to the backing material which contains as fillers metal sulfides, preferably molybdenum sulfide and/or tungsten sulfide, metal fluorides, lead, lead oxide, boron nitride, preferably hexagonal boron nitride, carbon modifications, preferably graphite, fibers, preferably carbon fibers, hard materials, colorants, iron (III) oxide and/or barium sulfate.
A method according to one of the preceding claims, characterized in that, as the metallic backing material, a roughened or porous strip of steel, bronze, brass, aluminum and/or an aluminum alloy, a composite material of steel and a porous or roughened layer of bronze, brass, aluminum and/or an aluminum alloy or a fabric of steel, bronze, brass, aluminum or an aluminum alloy is coated with the paste.
A method according to one of the preceding claims, characterized in that the paste is produced by coagulating a mixture of an aqueous, surfactant-containing polytetrafluoroethylene dispersion, a powder of the high temperature polymer and optionally a powder of the fillers.
A method according to one of the preceding claims, characterized in that the metallic backing material is coated with a paste to which one or more surfactants have additionally been added and/or which contains between 30 wt. % and 70 wt. %, preferably between 40 wt. % and 60 wt. % of water, in each case relative to the weight of the paste to be applied.
A method according to one of the preceding claims, characterized in that the paste contains one or more non-ionic surfactants.
A method according to one or the preceding claims, characterized in that the paste contains an alkyl polyglycol ester as surfactant.
A method according to one of the preceding claims, characterized in that the paste is rolled onto the backing material for coating purposes.
A method according to one of the preceding claims, characterized in that heat treatment of the backing material coated with the paste is performed at a temperature of between 360° C. and 420° C. for a treatment time of between 120 seconds and 180 seconds.
A method according to one of the preceding claims, characterized in that, immediately after heat treatment, compaction, especially hot compaction, is performed by means of a roll pair in such a way that the reduction in thickness of the overlay amounts to no more than 10%, relative to the thickness of the overlay prior to compaction.
Use of the sliding material produced according to one of the preceding claims in plain bearings or slide bushes.
Use of the sliding element produced according to one of the preceding claims in shock absorbers or pumps.
Use of the sliding element produced according to one of the preceding claims for applications in which it is necessary to post-machine, especially drill, ream, mill or broach, the sliding surface when the sliding element is in the installed state.
Dependencies are inferred from the claim text.