IL27165A - Dry lubricant coating - Google Patents

Description

•niuji jriD TJinj"! ·π PATENT ATTORNEYS ·. □ ' Q 1133 ' D11U DR. REINHOLD COHN DR. MICHAEL COHN ISRAEL SHACHTER B.Sc.

File CI 25794 PATENTS AND DESIGNS ORDINANCE SPECIFICATION Lubricant Coating ©a* ns»o 'is»n /WeAMPHMOL CORPOSATIOH, a corporation of Delaware, of 2801 South 25th Avenue, Broadview, Illinois, U,S»A. do hereby declare the nature of this invention and in what manner the same is to be performed, to be particularly described and ascertained in and by the following statement:— 27165/2 - lb - An object of the invention is to provide a strongly adherent dry lubricant coating. , A further object is to provide a method of quickly and economically producing an anodized metal surface having superior lubricating qualities to that of an ordinary anodized surface.

Another object is to provide a method of producing a dry lubricant comprising an anodized metal surface containing particles of a fluorocarbon polymer.

Other objects and advantages of the invention will become apparent as the following detailed description progresses.

In accordance with this invention a metal such as tin, aluminum or magnesium is electrolytically anodized as is well known to the art and while the anodization is taking place there is eljectrophoretically deposited on the metal particles of a solid lubricant. This simultaneous electrolytic growth of oxide and electrophoretic deposition of a lubricating media is accomplished by inicorporating in the electrolyte being used for the anodization a negatively charged particle of a solid lubricant. Thus, when the metal is made the anode and oxidation is taking place by electrolysis at the anode, the negatively charged particles of solid lubricant will migrate by means of the electric current induced in the bath to the anode and will be comingled with the oxide coating during its formation. This gives an extremely adherent low coefficient of friction coating useful as a bearing surface and for other uses of dry lubricants. This thickness of the coating is a function of the treatment time. Suitable coatings have been made with .001 inch thickness and as thick as .005 inch, but lesser and greater thicknesses can be attained.

The preferred metals used for simultaneous anodization and electrophoretic deposition of solid particles are aluminum, magnesium and the alloys containing a major proportion of such metals. The oxide coating produced is better suited for the comingling with solid lubricants such as fluorocarbon polymers, and gives a superior lubricating coat than produced by anodizing tin.

All types of solid lubricant particles which normally have or which can be made to have a negative charge may be used.

Thus particles of molybdenum disulphide, alumina-tungsten disulphide, polyethylene, and fluorocarbon polymers can be used. For lubricating purposes the fluorocarbon polymers are preferred, particularly the completely fluorinated fluorocarbon polymers, of which the best appears to be tetrafluoroethylene. The suitable fluorocarbon polymers include pol tetrafluoroethylene, polyhexafluoro rop lene, polychlorotrifluoroethylene, polyvinyl!dene fluoride, polyvinyl fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, vinyl-idene fluoride-hexafluoropropylene copolymer, poly 1,1,1-trifluoro-propylmethyldichlorosilane polymer, fluorosilicone elastomers, polyfluoroaniline, and copolymers of tetrafluoroethylene and tri-fluoronitrosomethane. The preferred completely fluorinated fluorocarbon from the point of view of coefficient of friction and all around value, is polytetrafluoroethylene. This material The following example illustrates the invention: EXAMPLE I An aluminum sheet is made the anode. The cathode is lead or stainless steel. The electrolyte consists of sulfuric acid (10 fluid ounces per gallon), oxalic acid (2 ounces per gallon), an aqueous suspension of negative charged colloidal particles of pol tetrafluoroethylene containing 0.5 per cent by weight TFE (TEFLON suspension No. 3170) acidulated with 5 per cent sulfuric acid, the ingredients being merged in water to a volume of two gallons. The electrolyte was contained in a glass tank and maintained at a temperature of 25° - 95°F during the operation.

The current density used was 10-36 amperes per square foot. The voltage was 10-75 volts. Vigorous agitation of the electrolyte was maintained. The time of operation was 15 to 60 minutes.

The coated plate produced by the above example had a coating of mixed aluminum oxide and particles of polytetrafluoroethylene of 0.0002 - 0.0025 inch thickness.

Substantially the same results as with the above example were obtained with the other fluorocarbon polymers above mentioned using the same procedure and conditions as in Example I. With particles of molybdenum disulphide and other metal sulfides a suitable comingled coating was also obtained by substituting a molybdenum disulphide aqueous dispersion for the TEFLON dispersion and otherwise keeping the conditions the same, although modification of the procedure to obtain better anodic deposition of the molybdenum disulphide could be carried out in accordance with procedures known to the art without interfering polymers but can also be electrophoretically deposited during electro anodization using the procedure and condition of Example I.

Claims (1)

1. CLAIKS An article comprising a member of a base an oxide of said metal and of substantial thickness anodized on a surface of said and solid lubricant particles of colloidal size mingled with said said particles being substantially uni ormly distributed throughout the thickness of said oxide and being locked place within randomly oriented within said oxide to form with said oxide a lubricating coating tightly bonded to said An article as defined Claim wherein said base metal is An article as defined in Claim wherein said solid cant particles are particles of a An article as defined Claim said solid lubricant particles are particles of molybdenum The article of Claim wherein the particles are of pol and wherein the metal is An article defined Claim wherein eaid solid lubricant particles are deposited and mingled with said oxide during anodising of oxide on method of making an article having a dry lubricant coating which comprises ly anodising a metal surface while simultaneously depositing particles of a solid lubricant on said The method of Claim wherein the metal is aluminum and the particles of solid lubricant are particles of a fluorocarbon The method of Claim wherein the metal is and the particles of solid lubricant are particles of The method of making an article having a dry lubricant coating which comprises making an aluminum eurfaeed object the anode an electroplating system comprising an cathode and electrolyte containing particles of negatively charged and passing eleetrie current through the electrolyte at a current density to the surface of the aluminum anode and simultaneously deposit the eaid polytetrafluoroethylene said insufficientOCRQuality