CA2094396A1

CA2094396A1 - Surface finishes and methods for the production thereof

Info

Publication number: CA2094396A1
Application number: CA002094396A
Authority: CA
Inventors: Gary E. Huggins
Original assignee: Individual
Current assignee: Eeonyx Corp
Priority date: 1991-08-26
Filing date: 1992-08-21
Publication date: 1993-02-27
Also published as: ZA926454B; EP0558724A4; CN1073213A; NO931446L; HU9301209D0; FI931868A0; WO1993003919A1; WO1993003921A1; BR9205402A; SK44993A3; JPH06501051A; MX9204930A; NO931445D0; EP0558724A1; AU2515392A; HUT67752A; CZ81593A3; AU2552592A; CA2094395A1; FI931869A0

Abstract

Thin impermeable, surface hardened, corrosion-resistant, durable, dry lubricant surface finishes are provided as well as surface finished products and methods for the production thereof. The surface finishes comprise particulate mixtures of sulfur containing metallic compounds and fluorocarbon polymers and are applied to surfaces of substrates such as metallic surfaces.

Description

2Q9~3~ 1 8~FAC~ FD~I8HES AND
METHODS FOR ~E P~ODUCTION T~ER~OF

TE~HNICAL FIELD
' This invention relates to surface finishes which impart nonabradable and nonetchable, dllrable dry r lubricity, corrosion resistance and improved wet film entrapment characteristics to a substrate and to methods for applying such surface ~inishes to a substrate.
Although this invention is primarily directed to the s~rface finishing of metallic substrates, it should be `` noted that it is likewise applicable to surface finishes for application to other suitable substrate materials such as ceramic compositions. Furthermore, it should be noted that the metallic ~ubstrates employed herein may range -~ from very hard metals having a hardness factor measured on ; the RockwPll C scale of greater than 40 to soft metals having hardness values measured on the RocXwell B scale.
Accordingly, a diversity of substrate materials may be utilized in this invention provided that the material has sufficient structural integrity to withstand the high pressure impact application techniques employed herein.
A wide variety of corrosion-resistant coatings as well as methods for the application of such coatings to substrates have been disclosed heretofore. Examples thereof may ble found in U.S. Patent Nos. 3,574,658;
3,754,976; 4,228,670; 4,312,900; 4,333,840; 4,415,419;
4,552,784; 4,553,417 and 4,753,094.

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2~9 43~ 6 -2-In this regard, several of the above-noted patents disclose processes for applying coatings ~o the surface of worX pieces by a peening or blasting procedure in which the coating material is applied to the surface by pellets or other shot material and is impacted at high pressure against the surface of the worX piece in order to apply the coating on the pellets or shot to the surface of the work piece. For example, in U.S. P~tent No. 3,574,658, a method is disclosed for applying a dry lubricant in the nature of a molybdenum or tungsten disulfide coating to the shot material and then applying this dry lubricant ~`~material to the surface of the work piece as a coating.
U.S. Patent No. 3,754,976 discloses a coating process wherein shot and powdered metal are peened against the surface of a work piece which has previously been cleaned with a gentle stream of peening particles in the absenca cf the coating material. U.S. Patent No. 4,228,670 discloses a process wherein steel or glass shot is co-mingled with lubricant and blasted against a work piece 20- in order to apply the lubricant to the work piece surface. U.S. Patent No. 4,312,900 discloses a process wherein the work piece surface is initially pitted by shot blasting using abrasive materials such as glass or sand `~ followed by buffing dry molybdenum disulfide into the pits created in the surface of the work piece by the shot blasting. U.S. Patent ~o. 4,552,784 discloses a further process for applying a ~etal powder to the surface of a work piece by a peening technique. Again, in U.S. Patent No. 4,753,094, a process is taught wherein a thin film coating of molybdenum disulfide is applied to a substrate surface by a peening action in order to adhere the molybdenum disulfide to the surface of the substrate as a coating thereon.

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WO~3~3919 PCT/US92/07062 2~943~

However, none of the prior disclosures have provided products demonstrating the combination of characteristics and properties which are achieved by the products of the present invention nor do they provide processes for producing such products. Indeed, the need to prolong the wear-life of substrate surfaces such as metal surfaces and to reduce the frictional properties thereof in order to ` reduce repair and replacement costs has been and continues to be the focus of intensive research and development -- 10 efforts. Nonetheless, these efforts have achieved only relatively limited success resulting from the use of previously known coatings, paints and lubricants (both wet and dry). Each of the known techniques for treating substrates such as metal surfaces has presented significant problems and drawbacks in regard to the cost, difficulties in application, product properties achieved and the like.
Particularly, it is presently believed that the processes of the present invention achieve surface modification whereby plural polymers are bonded wi~h the surfac~ o~ the treated wo~k piece or substrate. For purposes hereof, the term bond or bonded will apply to either physical or chemical bonds which result in products demonstrating the desired characteristics. Based on this ~elie~, it is presently hypothesized ~hat the surface finishes of this invention are not coatings but are permanently bonded with the substrate and can only be removed by grinding away the substrate surface itself.
Accordingly, the surface-finishing processes of the present invention result in products with permanent finishes having a degree of long lasting, durable dry lubricity and corrosion resistance which has not been achieved heretofore.

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Wos3/03919 PCT/VS9~/070~

2~9 ~396 ~4~
With regard to prior processes for imparting desirable .-physical properties of polymers to substrate surfaces such as metal surfaces, it has been common to employ fluorocarbon polymers such as t:etrafluoroethylene (TFE) sold, for example, unde.r the tradename "Teflon" by E.I. Du Pont de Nemours ~ Co. (Inc.), as a coating material.
Teflon coated surfaces are known to reduce friction and adhesion but must be applied to the substrate by use of primers such as epoxy. The coated surface, accordingly, abrades under modest pressure, does not coat evenly or thinly and requires high temperatures for application.
_ . . . . .
SUMMARY OF THE INVENTION
-The present invention overcomes many of the known shortcomings of the prior art. The invention comprises preparing a particulate mixture of a sulfur containing metallic compound such as molybdenum disulfide or tungsten disulfide and a fluorocarbon polymer such as tetrafluoroethylene, preferably in a ratio of about 1:1 to about 10:1 parts fluorocarbon polymer to sulfur containing metallic compound (on a weight percentage basis).
A pressurized stream of the particulate mixture is impacted onto the surface of a substrate at a sufficient pressure and for a sufficient period of time to cause ~5 surface modification whereby the particulate mixture interacts with the substrate. As a result of the application of such surface finishes to the surface of the substrate, it has been found that the resulting product demonstrates outstanding corrosion resistance as well as long lasting, durable dry lubricity characteristics.
Furthermore, the surface finishes have been found to provide a relatively thin, impermeable, surface hardened exterior on the surface of the substrate or work piece.

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These surface finishes have been found to be sufficiently thin so that the finishes do not interfere with critical tolerances of any processed parts or components.
Accordingly, it is a general object of the present invention to provide new and i~proved surface finishes for ` application to substrates and to provide me hods of applying such surface finishes to substrates.
`~ Another object is to provide corrosion-resistant surface finishes demonstrating long lasting, durable dry lubricity characteristics as well as providing an impermeable, surface hardened outer surface on a substrate.
A further object is to provide methods for producing ; corrosion-resistant, long lasting, durable dry lubricant surface finishes on substrates.
A f~rther o~ject is to provide a surface finished product having a high degree of permanent dry lubricity.
Another object is to provide a metal surface exhibiting long lasting, durable dry lubricity and high resistance to temperature extremes.
A still further object is to provide methods for producing thin surface finishes which exhibit long lasting, durable dry lubricity; corrosion and heat resistance as well as improved thin film entrapment (or retention) properties.
Yet another object is to provide methods for relatively easy and inexpensive application of the surface finishes of this invention to substrate surfaces. `
Other objects of this invention, in addition to those set forth above, will become apparent to one of ordinary skill in the art from the following description.

W093/03919 PCT/US92/07n~2 2~3~ -6-BRIEF DESCRIPTION OF THE DRAWING
Fig. l is a schematic flow diagram illustrating the method of the present invention employed to apply a dry lubricating, corrosion-resistant finish to the surface of a substrate.

DETAILED DESCRIPTION
The drawing is a schematic rlow diagram showing an embodiment of the methods of the present invention for applying surface finishes to a substrate.
In the embodiment of this invention depicted in Fig.
l, a multistep process is illustrated wherein a substrate surface is first subjected to an optional solvent precleaning step in ord~r to remove any loose surface contamination such as hydrocarbons and other physical and chPmical debris from the substrate prior to further processing. This precleaning step is employed in order to reduce contamination which may be encountered and which may thereby interfere with the blast application of the surface finish onto the substrate.
The appropriate solvent to be used for this precleaning is somewhat substrate spacific. For example, very dirty, greasy substrates will require a Stoddard solvent to be employed to clean the substrate surface.
For substrate surfaces which are non-degassing, such as chrome/molybdenum or stainless steel, 1,1,1 trichloroethane or equivalent solvent may be employed in an ultrassnic cleaning procedureO For degassing substrates, a Branson IS solvent is employed in an ultrasonic cleaning procedure.
In a specific solvent precleaning process employed in the laboratory, a metallic substrate was brush scrubbed in Stoddard solvent with Hurri-Safe Special Formula Degreaser WO93~0391s PCT/US92/07062 20~3~
at a 1:4 dilution in a Hurri Kleen cold part washing machine and the substrate was then air dried. Thereafter, the material was cleaned in either Branson IS Formulated Cleaning Solution, 1:10 dilution or 1,1,1 trichloroethane precleaner (sold by Brownells) utilizing an indirect method in a Branson 8200 Ultrasonic Cleaner filled with Branson IS Formulated Cleaning ',olution, 1:10 dilution.
Cleaning time was about 15 minut:es at 40 C.
As illustrated in the drawing, after completion of the solvent precleaning step, the substrate is then subjected to an abrasive cleaning/surface disruption step to create a sufficient and appropriate amount of disrupted surface ;~ area on the surface of the substrate in order to interact wi~h the surface finish material to be applied thereafter. In this abrasive cleaning step, any oxidation or contamination from the substrate material which was not removed in the precleaning step is removed.
This abrasive cleaning/surface disruption step may be performed in a blast cabinet environment in accordance with the procedures disclosed for precleaning in U.S.
Patent No. 4,753,094 (the disclosure of which is incorporated herein by reference). The specific parameters of treatment within this step of the process are subject to choice, depending on the substrate material and its intended end use. For example, the delivery pressure/velocity, temperature, angle of delivery, duration of blasting and like parameters o~ the process are subject to choice and will vary depending on whether final treatment of the substrate is intended to increase dry lubricity, wear resistance, quick release (i.e., non-sticking effect), operative temperature range and/or corrosion resistance.

W093/039l9 PCT/US92/07~t 2~ 439~ -8-In regard to the blast materials to be used for this abrasive cleaning/surface disruption step, it has been found that for softer, nonferrous metals and alloys, (e.g., aluminum, copper, lead, magnesium, zinc, beryllium, gold, tin, bronze, brass, etc.); glass beads, nylon or plastic particles or aluminum shot may be employed for blast cleaning the surface of the substrate. For harder, nonferrous metals (e.g., nickel) and for ferrous metals and alloys, (e.g., iron, molybdenum, chromium, tungsten, vanadium, steels and stainless steel) aluminum oxide particles, silicon carbide particles, glass beads, sand particles, steei shot and the like may be used to provide the peening action in cleansing the surface of the substrate. In this regard, it has been found that less aggressive media (e.g., glass beads) may be used for applications where a characteristic such as quick release or non-sticking is desired, while more aggressive media such as aluminum oxide or silicon carbide are preferred for use in applications where end product characteristics such as increased wear resistance or dry lubricity are desired.
In regard to the delivery pressures to be employed for performing this abrasive cleaning step, it is believed that pressures up to 250 psi may be employed for hard and very hard substrates such as chrome/molybdenum steels and tungsten carbides, whereas lower delivery pressures of as low as about 20 psi may be used in other applications. As employed herein, the term "delivery pressure" is defined as the blast pressure applied to a substrate at a distance of two inches from the nozzle of the delivery device.
The temperature range to be employed in performing this abrasive cleaning step appears to be a matter of selection and not to be determinative of the quality of ` ' ''`~

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-9- ~'1396 the surface treatment achieved. However, it has been found that temperatures ranging between ambient temperatures and about 50 C are suitable for this cleaning step.
In specific abrasive cleaning/sllrface disruption processes employed in the laboratory, substrates which were to be cleaned/disrupted with aluminum oxide (extra fine grade-Brownells) utilized a Techni Blast Model 36 Cleaning Machine, sold undar the trademark "SURFGARD" at 58 cubic feet per minute at 100 pounds pressureO This cleaning machine was eguipped with a 3/16 inch blast gun with a ceramic nozzle. Alternatively, substrates which were to be cleaned/disrupted with glass beads (#270 U.S.
Sieve Size-Brownells) were blasted utilizing a Trinco Direct Pressure Cabinet Nodel 36X30/PC equipped with a 1/4 inch nozzle I~Do and the substrate was blasted at 60-120 psi (preferably about 80-100 psi) at a distance of between about ~ inches and 12 inches (prefexably about 6-8 inches~
~t an angle of about 20 - 90 (preferably about 30 -60) until a uniformly disrupted surface was obtained and all surface contamination was removed.
In step three illustrated in the drawing, the substrate is air cleaned with dry, compressed air to - remove any residual cleaning/disrupting media thereby avoiding any possible cross-contamination with different media.
Once the preliminary cleaning steps one, two and three are completed, the substrate is then in condition to be processed in accordance with the present invention.
In accordance with the present invention, a pressurized stream of a particulate mixture of a sulfur containing met:allic compound and a fluorocarbon polymer is directed in a pressurized stream to impact against the " ' ' ' ' ' '; " ' . ' " ,` . ' . `"' WO93/03919 pcT/us92/o7nk2 3 ~ ~

surface of a substxate at a sufficient pressure and for a sufficient period of time to cause ths particulate mixture to interact ~ith the substrate and to provide a surprisingly thin, impermeable, surface hardened, corrosion-resistant, durable, dry lubricant finish on the surface of the substrate.
In practice, the substrate s;urface to be treated is preferably a metallic surface. HQwever, as previously noted herein, the substrate may be any suitable ferrous or nonferrous metal or alloy of a metal or a ceramic composition.
In order to expedite the impacting or peening of the particulate matter against the surface of the substrate, it has bean found that suitable peening media having suitable shot sizes should be employed for purposes of conveying the mixture to the previously disrupte~ surface of the substrate. Another purpose of the peening media in addition to providing a carrier for the surfaca ~inish particulate material is to surface harden the substrate through the peening process. A suitable peening medium for purposes of use in the present process is chosen as a function of its compatibility with the subs rate and its affinity for the particulate surface finish material which it is carrying.
In addition, the size and hardness of the peening media have been found to influence thP effective transfer of the surface finish material to the cleansed, disrupted substrate surface. In this regard, wP have found that shot sizes ranging from SAE Size No. S70 to about S780 30 (preferably about Size No. S70 and S230; most preferably about Size S170) may suitably be employed in the processes of this invention. In particular, we have found that with softer metal substrates (such as those on the Rockwell B

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20943~6 scale or on the Rockwell C scale ratings of ~0 and below), use of larger size shot (such as about SAE Size ~o. 170 and above) is preferred in order to achieve maximum surface finish coverage. Also, we have found that with 5 harder metals (Rockwell C scalt3 ratings of 40 and above), such large shot (i.e., SAE No. S170 and above) is likewise preferred for purposes of achie~ing continuous surface covsrage. However, it is to be noted that smaller size shot may also be employed in certain applications to avoid surface asperities.
Examples of suitable peening media which may be used herein are steel shot, stainless steel-shot, aluminum ~~
shot, piastic shot and the like having sufficient structural integrity to withstand impact on the substrate sur~ace.
In general, the surface finish composition of this invention is a particulate mixture of solid lu~ricants formulated to provide dry lubrication and/or corrosion resistance andJor non-stick properties desired for purposes of the end use of the product. Suitable solid lubricants for use in tha particulate mixtures of the present invention include fluorocarbon polymers and carrier or binder polymers.
Exemplary of suitable fluorocarbon polymers are homogenates or mixtures of finely-divided fluorocarbon resins having fully fluorinated carbon backbones such as tetrafluoroethylene homopolymer (TF2), hexafluoropropylene (~FP), perfluoroalkoxyvinyl ether (PPVE), copolymers of TFE and HFP, copolymers of TFE and PPVE. Other suitable fluorocarbon polymers are fluoropolymer resins which are not fully fluorinated such as ethylenetetrafluoroethylene (ETFE), polyvinylidene fluoride (PVDF), ethylene-chlorotrifluoroethylene (ECTFE~, copolymers of ethylene ,: :: -... . ..... ..
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W093/03919 PCT/US92/070fi2 2~ ~ ~S~9~ -12-and TFE such as products sold under the trademark "Tefzel"
by E.I. Du Pont de Nemours & Co. (Inc.). The molecular weight of the fluorocarbon polymers to be used herein may vary over a relatively wide range although molecular weights of from about 800 to about 2000 are preferred and, particularly about lO00-l800. Furthermore, it should be noted that mixtures of fluorocarbon polymers of varying molecular weights may be advantageously employed herein as, for example, mixtures of tetrafluoroethylenes having molecular weights of llOO and 1300.
In summary, the fluorocarbon pol~mers are chosen for - their ability to impàrt their individual characteristics to the substrate and for their affinity to the substrate, the peening media employed, and/or the other solid lubricant material chosen. Furthermore, suitable fluorocarbon polymers ~or use herein are impermeable and chemically unreactive to water and other solids, W
radiation and gases. The polymers are highly thermally stable and will withstand high upper surface temperatures 20 ti.e., about 204 C - 260~ C~ as a result of their high C-F and C-C bond,strengths and the resulting non-polar nature of the linear polymer. These resins have a low coefficient of friction and a low dielectric constant and dissipation factor. They exhibit a high deyree of linear flexibility and are flame resistant.
The other solid lubricant component of the particulate mixture employed herein is a sulfur containing metallic compound which acts as a carrier or binder molecule herein. Suitable metal sulfides for purposes of the present invention possess anti-friction/dry lubrication capabilities, can withstand increased operating temperatures and/or demonstrate high affinity towards metals such as those employed as the substrates herein or .: . ~ : ~: . ; ;

W093/03919 PCT/US92tO7062 2~9433~

the peening media utilized herein as well as demonstrating high affinity toward the fluorocarbon polymers selected as part of the surface treatment mixture.
Representative of suitable sulfur containing metallic compounds for use herein are sulfides of molybdenum, tungsten, lead, tin, copper, calcium, titanium, zinc, chromium, iron, antimony, bismuth, silver, cadmium and alloys and mixtures thereof.
In a preferred form, molybdenum disulfide is employed as the sulfur containing metal compound in the particulate mixtures employedO Molybdenum disulfide has a high affinity to steel and other base metals and has the ability to increase surface hardness, corrosion resistance, elevated temperature strength and dry lubricity. It also has a high affinity to fluorocarbon micropowders which may be employed advantageously herein.
Thus, it has been found that use of molybdenum disulfide herein provides the dual function of a dry lubricant additive as well as a carrier/binder molecule for the fluorocarbon polymer to promote coating of the peening media~ ' In general, the amount of fluorocarbon pol~mer to be incorporated in tha particulate mixture to provide the requisite surface finish is determined by the amount of such polymer required to saturate the carrier or binder molecule such as molybdenum disulfide. The total amount of the particulate mixture to be employed for applying the surface finish to the substrate via a peening action in a blast cabinet is determined by the amount of material required to keep the peening medium completely coated during the blasting operation in the cabinet.
In a laboratory example of the practice of the present invention, a T~echni Blast Model 36 SURFGARD Peen Plating ' . - : . : . ': ' ' ' . . : :. , '.:. .::, . . . . .

WO93/03gl9 PCT/U~92/07~?.

2~9~396 Machine, 70 cubic feet per minute at 100 pounds pressure, 3/16 inch Suction Blast Gun wit:h Ceramic Nozzle was employed for directing the part:iculate mixture against the surface of a substrate in a blast cabinet. The cabinet was loaded with 500 ml. (by volume) molybdenum disulfide (Super Fine Grade, Lot #510DS, Climax Molybdenum Co.); 500 ml. (by volume) tetrafluoroethylene having a molecular weight of about 1100 (Teflon F]uoroadditive Type MP1100, Lot #BMAB40D002, Du Pont); 500 ml. (by volume) tetrafluoroethylene having a molecular weight of about 1300 (Teflon Fluoroadditive Type MP1300, Lot #68-86, Du Pont) and 200 pounds of S70 steel shot (Techni Blast).
The blast cabinet temperature was maintained at about 50 C and the delivery pressure at the nozzle of the peen plating machine was 80 psi. The particulate mixture with the peening medium was blasted at a 45 angle at a distance of about ~-8 inches until a uniform, void-free surface treatment had been achieved.
After completion of step four in the drawing wherein the finish surface is applied to the substrate in accordance with the method of the present invention, it has been found that the resulting product may advantageously be subjected to a post-treatment cleaning and preservation step (step five in the drawing). In this step of the process, the substrates having the inventive surface finish applied therein are cleaned with dry, compressed air to remove any residual surface treatment particles. Thereafter, the substrate is washed with a cleaning solution and preserved with an oil that is compatible with the end use of the material, if so desired.
In a preferred embodiment of the present invention, a surface finish is produced in the surface of a two inch by two inch square, 1/4 inch thick chrome/molybdenum steel r ,, ` ' , : ' ' :: .:, ~, .. ''' " ': ":': ' ::. ': . ' ': . : ' "
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, ' ' ::, . . '; : : . ' , ~ . ' l -15- ~ ~9 ~3g6 sample. The hardness of the chrome/molybdenum steel sample was 53 as measured on thle Rockwell C scale. In the process, after subjecting the steel sample ko appropriate solvent precleaning, the sample was subjected to an abrasive cleaning/surface disru]ption step in a cabinet wherein aluminum oxide shot was impacted onto the steel surface at 60 psi at an angle oE about 45 under ambient temperature conditions.
Thereafter, the sample was introduced into a blast cabinet and a Techni Blast Model 36 SURFGARD Peen Plating Machine having a 3/16 inch Suction Blast Gun with Ceramic Nozzle was employed t-o`direct a particulate mixture against the surface of this sample. The particulate mixture was prepared by mixing 22 ounces (by weight) tetrafluoroethylene having a molecular weight of about 1500 ~Teflon Fluoroadditive Type MP1500J, Lot #999999) in a container with lOO lbs. of SAE No. S170 steel shot.
Then, an additional 14.5 ounces (by weight) of tetrafluoroethylene (MP1500J) was admixed with tha steel shot in the sama container. In a separate container, 30 ounces (by weight) of molybdenum disulfide (Super Fine Grade, Lot #~lODS, ~limax Molybdenum Co.) was mixed with 100 lbs. of SAE No. S170 steel shot.
The contents of the two containers were then mixed together and an additional 24.3 ouncas ~by weight) of tetrafluoroethylene (MP1500J) was added to the mixture.
The combined mixture contained 60.8 ounces ~by weight) tetrafluoroethylene, approximately 30 ounces (by weight) molybdenum disulfide and about 200 lbs. SAE No. S170 steel shot. The resulting combined mixture contained a ratio by weight of tetrafluoroethylene to molybdenum disulfide of about 2:1.

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The blast cabinet temperature was maintained at about 50 C and the d~livery pressure at the nozzle of the peen plating machine was 80 psi. The steel shot peening medium having the particulate mixture intimately coated on the surface of the shot was blastedl onto the precleaned, disrupted surface of the sample at an angle of about 450 at a distance of about 4 inches for a period of about 15 seconds to form a uniform, void-free surface on the surface of the chrome/molybden~m steel sample.
Subsequent to the blast treatment, the sample was subjected to a post-treatment cleaning step by subjecting the sample to Stoddard solvent in a Hurri-Kleen Station.
This cleaning step was followed by subsequent cleaning of the resulting product in 1,1,1 - trichloroethylene in a 15 1000 ml. beaker and the resulting cleaned surface finish product was subjected to air drying before evaluation.
The resulting product was found to have a nonabradable, nonetchable surface which was durable, corrosion resistant and demonstrated dry lubxicity and 20 exceptional wet film entrapment characteristics.
~hus, a method has bèen described herein for producing a surface finish on a substrate in a manner such that the resulting product exhibits a wide range of benefits 3 otherwise unavailable. The surface finished product ~5 demonstrates permanent dry lubricity and is highly resistant to temperature extremes. Furthermore, the ; surface finished product provides a natural barrier to normal oxidation and corrosion since it is chemically inert. In addition, the finish in the treated substrate 30 surface exhibits exceptional durability and is extremely thin, being measured as low as about 0.5 micron thickness as opposed to prior art coatings wherein the coat is measured in mils such as the industry standard electroless - . , . .

W093/03~9 PrT/US92/07062 -17 2~91~3~

nicXel coatings which have a thickness of 3/8 mil when submerged in nickel plating solution for 45 minutes at 90.5 C. Still further, the surface finishes of the present invention are applied relatively easily even at relatively low temperatures and inexpensively in order to provide the desired surface modification herein.
The products produced in accordance with this invention have a multiplicity of uses in a variety of industries and in products containing metal on metal friction points or which are subject to metal surface corrosion. Exemplary of the scope of the utiIization of the present invention are applications within the automotive industry, fuel handling systems, power tools and equipment, fasteners, ball bearings, rollers and other anti-friction components, consumer products including cookware, houseware and razor blades, turbines, gears and other intermeshing machinery as well as a variety of other potential uses.
Although the invention has been described in its preferred form with a certain degree of particularity, it is to be understood that the present disclosure has been made by way of example only. Numerous changes in the details and operational steps of the methods and in the materials utilized therein will be apparent without ~5 departing from the spirit and scope of th~ invention, as defined in the appended claims.

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Claims

We Claim:

1. A method of producing a surface finish in a surface of a substrate comprising:
preparing a particulate mixture of a sulfur containing metallic compound and a fluorocarbon polymer;
projecting a pressurized stream of material containing the particulate mixture at the surface of the substrate;
and impacting the surface of said substrate with said stream of material at a sufficient pressure for a sufficient period of time to cause said particulate mixture in said stream to interact with said surface of said substrate providing a thin impermeable, surface hardened, corrosion-resistant, durable, dry lubricant finish in the surface of said substrate.

2. The method of claim 1 wherein said substrate is a metal.

3. The method of claim 1 wherein said substrate is a ceramic composition.

4. The method of claim 1 wherein said particulate mixture bonds with said surface of said substrate upon impacting of said stream of material on said surface.

5. The method of claim 1 wherein said sulfur containing metallic compound is molybdenum disulfide.

6. The method of claim 1 wherein said sulfur containing metallic compound is selected from the group consisting of sulfides of tungsten, lead, tin, copper, calcium, titanium, zinc, chromium, iron, antimony, bismuth, silver, cadmium and alloys and mixtures thereof.

7. The method of claim 1 wherein said fluorocarbon polymer is tetrafluoroethylene.

8. The method of claim 7 wherein said tetrafluoroethylene has a molecular weight of about 800-2000.

9. The method of claim 1 wherein said fluorocarbon polymer is a mixture of different molecular weight tetrafluoroethylenes including a tetrafluoroethylene having a molecular weight of about 1100 and a tetrafluoroethylene having a molecular weight of about 1300.

10. The method of claim 1 wherein said fluorocarbon polymer is selected from the group consisting of hexafluoropropylene, perfluoroalkoxyvinyl ether, copolymers of tetrafluoroethylene and hexafluoropropylene, copolymers of tetrafluoroethylene and perfluoroalkoxyvinyl ether, ethylenetetrafluoroethylene, polyvinylidene fluoride, ethyl-chlorotrifluoroethylene, copolymers of ethylene and tetrafluoroethylene and mixtures thereof.

11. The method of claim 1 wherein the stream of material is projected at a pressure of between about 20 psi and about 120 psi.

12. The method of claim 1 wherein said pressurized stream of material includes peening media selected from the group consisting of steel shot, stainless steel shot, aluminum shot, plastic shot and mixtures thereof.

13. The method of claim 1 including precleaning the surface of said substrate prior to impacting said surface with said stream of material.

14. The method of claim 13 wherein said precleaning includes an abrasive cleaning and surface disruption treatment.

15. The method of claim 1 including subjecting said substrate to a cleaning and preservation treatment subsequent to impacting said surface of said substrate with said stream of material.

16. A method of producing a surface finish in a surface of a metal substrate comprising:
preparing a particulate mixture of molybdenum disulfide and a fluorocarbon polymer;
projecting said particulate mixture in combination with a peening medium at the surface of the metal substrate; and impacting the surface of said substrate with said combination of peening medium and particulate mixture in a manner such that said particulate mixture interacts with said surface of said substrate providing an impermeable, surface hardened corrosion-resistant durable dry lubricant finish in the surface of said substrate.

17. The method of claim 16 wherein said fluorocarbon polymer is tetrafluoroethylene.

18. The method of claim 17 wherein said particulate mixture chemically bonds with said surface of said metal substrate upon impacting of said combination of peening medium and particulate mixture on said surface.

19. The method of claim 17 wherein said tetrafluoroethylene has a molecular weight of about 800-2000.

20. The method of claim 16 wherein said fluorocarbon polymer is a mixture of different molecular weight tetrafluoroethylenes including a tetrafluoroethylene having a molecular weight of about 1100 and a tetrafluoroethylene having a molecular weight of about 1300.

21. The method of claim 16 including precleaning the surface of said metal substrate prior to impacting said surface with said stream of material.

22. The method of claim 21 wherein said precleaning includes an abrasive cleaning and surface disruption treatment.

23. The method of claim 16 including subjecting said substrate to a cleaning and preservation treatment subsequent to impacting said surface of said substrate with said stream of material.

24. A surface finished product comprising:
a substrate having a surface thereon; and a particulate mixture of a sulfur containing metallic compound and a fluorocarbon polymer interacting with said surface of said substrate to provide an impermeable, surface hardened, corrosion-resistant, durable, dry lubricant finish in the surface of said substrate.

25. The product of claim 24 wherein said substrate is a metal.

26. The product of claim 24 wherein said substrate is a ceramic composition.

27. The product of claim 24 wherein said particulate mixture is chemically bonded with said surface of said substrate.

28. The product of claim 24 wherein said sulfur containing metallic compound is molybdenum disulfide.

29. The product of claim 24 wherein said sulfur containing metallic compound is selected from the group consisting of sulfides of tungsten, lead, tin, copper, calcium, titanium, zinc, chromium, iron, antimony, bismuth, silver, cadmium and alloys and mixtures thereof.

30. The product of claim 24 wherein said fluorocarbon polymer is tetrafluoroethylene.

31. The product of claim 30 wherein said tetrafluoroethylene has a molecular weight of about 800-2000.

32. The product of claim 24 wherein said fluorocarbon polymer is a mixture of different molecular weight tetrafluoroethylenes including a tetrafluoroethylene having a molecular weight of about 1100 and a tetrafluoroethylene having a molecular weight of about 1300.

33. The product of claim 24 wherein said fluorocarbon polymer is selected from the group consisting of hexafluoropropylene, perfluoroalkoxyvinyl ether, copolymers of tetrafluoroethylene and hexafluoropropylene, copolymers of tetrafluoroethylene and perfluoroalkoxyvinyl ether, ethylenetetrafluoroethylene, polyvinylidene fluoride, ethyl chlorotrifluoroethylene, copolymers of ethylene and tetrafluoroethylene and mixtures thereof.

34. A surface finished product comprising:
a metal substrate having a surface thereon, and a particulate mixture of molybdenum disulfide and a fluorocarbon polymer interacting with said surface of said substrate to provide an impermeable, surface hardened, corrosion-resistant, durable, dry lubricant finish in the surface of said substrate.

35. The product of claim 34 wherein said fluorocarbon polymer is tetrafluoroethylene.

36. The product of claim 35 wherein said particulate mixture is chemically bonded with said surface of said metal substrate.

37. The product of claim 35 wherein said tetrafluoroethylene has a molecular weight of about 800-2000.

38. The product of claim 36 wherein said fluorocarbon polymer is a mixture of different molecular weight tetrafluoroethylenes including a tetrafluoroethylene having a molecular weight of about 1100 and a tetrafluoroethylene having a molecular weight of about 1300.