ATBECHDE..ESFRGBGRITLILUNLSE......................RDIM360 - Ver 2.5 (21 Aug 1997) 2100000/1 2100000/20285722EUROPEAN PATENT SPECIFICATIONB119920102EP87308177.2198709161989012419900720enenen3534619870407US871946319870818GB199201021992011988101219884119920102199201199102195 5C 23C 4/18 A 5C 23C 28/00 BdeLuftgehärtete Kompositbeschichtung und Verfahren zu ihrer AnwendungenAn air cured composite coating and method for applying samefrRevêtement composite cuit à l'air et son procédé de fabricationFR-A- 1 523 222US-A- 3 010 843PATENT ABSTRACTS OF JAPAN, vol. 10, no. 103 (C-340)[2160], 18th April 1986; & JP-A-60 234 960 (SEIKO DENSHI KOGYO K.K.) 21-11-1985PATENT ABSTRACTS OF JAPAN, vol. 7, no. 77 (C-159)[1222], 30th March 1983; & JP-A-58 9971 (SUWA SEIKOSHA K.K.) 20-01-1983PATENT ABSTRACTS OF JAPAN, vol. 9, no. 301 (C-316)[2024], 28th November 1985; & JP-A-60 138 064 (SHOWA DENKO K.K.) 22-07-1985Carlo, Gary R.49 Stonehenge Place WatertownConnecticut 06795USPLASMA COATINGS, INC.00900910P O Box 10006Waterbury Connecticut 06725-0006USArcher, Philip Bruceet al00027751Urquhart-Dykes & Lord European Patent Attorneys New Priestgate House 57 PriestgatePeterborough Cambridgeshire PE1 1JXGBATBECHDEESFRGBGRITLILUNLSE19881214198850

The present invention relates to a composite coating which imparts an abrasion resistant release surface to a substrate and a method for applying the coating to the substrate. More particularly, the present invention relates to an air cured composite coating comprising a porous metal matrix and a silicone impregnant which seals the porosity of the matrix.

Composite coatings applied to substrates to enhance their abrasion resistence and release properties are old in the art. Prior art composite coatings usually include either a ceramic or a metal matrix applied to a substrate, with the matrix being impregnated with a silicone polymer or fluorocarbon polymer release agent. The major drawback to all the prior art composite coatings is that they must be heat cured at temperatures near or above 260 degrees Celcius (500 degrees fahrenheit). Heat curing of the composite coating presents significant problems where the substrate is of substantial size or weight or where the substrate is a component of a larger machine. Where the substrate is large and/or heavy, it may be expensive to ship the substrate to a distant coating facility. Further, when the substrate is a component of a larger machine, productivity of the machine is lost while the component is removed from the machine and sent away to be coated.

There is disclosed in U.S.3,010,843 a coating and a method of applying same as defined in the pre-characterising portions of claims 1 and 6 hereof.

According to the invention there is provided a coating and a method of applying same as defined in claims 1 and 6 hereof.

In the described embodiments there is provided a composite coating which imparts an abrasion resistant release surface to a substrate where, because the composite coating is air cured, it can be applied on site. That is, because the composite coating does not require oven-heating for proper curing, the substrate does not have to be shipped to a distant coating facility. The air cured composite coating comprises a porous metal matrix impregnated with a silicone to seal the porosity of the matrix. The coating is continuously operable to temperatures of up to 204 degrees Celcius (400 degrees fahrenheit) and exhibits a hardness of up to 72 Rc.

In the accompanying drawings:-

In accordance with the present invention, a porous metal matrix is initially formed on a substrate and then impregnated with a film forming, polymerizable, silicon impregnate which is polymerized in situ to serve as a release agent. The resulting composite coating thus formed has the abrasion resistance of the metal matrix and the release properties of the impregnating silicon.

Referring to Fig. 1, a substrate coated with the air cured composite coating of the present invention is shown generally at 10. The substrate 12, such as an idler roller or drum, carries the composite coating, represented at 14. As shown in Fig. 2, the composite coating comprises a porous metal matrix which in cross section exhibits a multitude of depressions 16 and plateaus 18 formed therein. A film forming, polymerized, silicone impregnate 20 fills the depressions 16 in the matrix 14 and penetrates into the matrix to seal its porosity. It is also preferred that an excess of the impregnate 20 extends above the plateaus 18 to completely cover the matrix 14.

In accordance with the present invention, the metallic matrix is applied to the substrate 12 in a flame spraying process. The material of the metal matrix 14 may vary widely within the scope of the invention, and can be of any metal which is of powder form, for example metals from the group consisting of stainless steel, nickel, nickel chromium, and molybdenum. The metal matrix 14 is deposited onto the substrate 10 to a depth of from 0.0051 to 0.025 millimetres (0.002 to 0.010 of an inch), depending upon the purpose for which the coated substrate is employed.

Further, and in accordance with the present invention, the silicone may be applied to the metal matrix 14 such that the silicone fills the depressions 16, extends above the plateaus 18 and penetrates into the matrix 14. It is permitted to polymerize in situ at ambient temperatures for a period of from 16 to 24 hours. As noted above, this is the major advantage of the present invention over prior art composite release coatings; the coating can be applied and air cured on site, eliminating the need for heat-curing in an oven.

The composite coating which results has a hardness of up to 72 Rc and a surface finish of from 6.35 to 17.78 micrometres (250 to 700 microinches). The composite exhibits thermal stability at continuous operating temperatures of up to 204 degrees Celcius (400 degrees fahrenheit) and intermittent operating temperatures of up to 260 degrees Celcius (500 degrees fahrenheit). The composite coating also provides 2 1/2 - 3 times longer release life than composite coatings utilizing fluorocarbon release agents. In the case of certain adhesives, absolute release is offered with no adhesive transfer onto the release surface, whereas resistance as well as adhesive transfer is apparent when used with the above mentioned fluorocarbon release coatings. It also has a high coefficient of friction which is desirable for web tracking.

 A composite coating for imparting an abrasion resistant release surface to a substrate, said composite coating comprising:
   a porous metal matrix thermally sprayed onto said substrate to a depth of 0.051 to 0.025 millimetres (0.002 to 0.010 of an inch), said matrix comprising a metal of powdered form, and
   a film of silicone impregnating said matrix to seal the porosity of the matrix,
   characterised in that
   said metal matrix has a multitude of depressions and plateaus formed therein, and
   said film of silicone fills said depressions and extends above said plateaus to completely cover said matrix, and
   said film of silicone has been air cured at ambient temperatures so as to have a surface hardness of up to 72 Rc, and maintains thermal stability at a continuous operating temperature of up to 204 degrees celsius (400 degrees farenheit) and maintains thermal stability at an intermittent operating temperature of up to 260 degrees celsius (500 degrees farenheit). The composite coating of claim 1 characterised in that the metal of powdered form is selected from the group consisting of stainless steel, nickel, nickel chromium, and molybdenum. The composite coating of claim 1 or claim 2 characterised in that said coating has a surface finish in the range of 6.35 to 17.78 micrometres (250 to 700 micro-inches). The composite coating of any one of claims 1 to 3 characterised in that said air cured silicone has been polymerised within a period of 16 to 24 hours. A method of applying a composite coating to a substrate, comprising the steps of:
   providing a substrate,
   applying a porous metal matrix to said substrate to a depth of 0.051 to 0.025 millimetres (0.002 to 0.0010 of an inch) in a flame spraying process, said metal matrix comprising a metal of powdered form,
   impregnating a film of silicone into said metal matrix to seal the porosity of said matrix, and
   curing said silicone impregnated into said matrix,
   characterised in that
   said metal matrix has a multitude of depressions and plateaus formed therein,
   said film of silicone fills said depressions of said metal matrix and extends above said plateaus thereof to completely cover said matrix,
   said curing of said silicone being carried out by air curing at ambient temperature for a period of 16 to 24 hours. A method according to claim 5 characterised in that said metal matrix is applied to said substrate by a metal spraying technique. Kompositbeschichtung, um einem Substrat eine abriebfeste Trennfläche zu verleihen, wobei die Kompositbeschichtung aufweist:
eine poröse Metallmatrix, die thermisch auf das Substrat in einer Dicke von 0,051 - 0,025 mm (0,002 - 0,010 inch) aufgesprüht ist, wobei die Matrix ein Metall in gepulverter Form aufweist, und
einen Film aus Silikon, der die Matrix imprägniert, um die Porosität der Matrix abzudichten,
dadurch gekennzeichnet, daß
die Metallmatrix eine Vielzahl von Vertiefungen und darin gebildeten Ebenen hat, und
der Film aus Silikon die Vertiefungen füllt und sich über die Ebenen erstreckt, um die Matrix vollständig abzudecken, und
der Film aus Silikon bei Umgebungstemperaturen luftgehärtet wurde, um eine Oberflächenhärte von bis zu 72 Rc zu haben, und eine Wärmestabilität bei fortlaufenden Betriebstemperaturen bis zu 204° C (400° F) aufrechterhält sowie eine Wärmestabilität bei kurzzeitigen Betriebstemperaturen von bis zu 260° C (500° F) aufrecht erhält. Kompositbeschichtung nach Anspruch 1, dadurch gekennzeichnet, daß das Metall in gepulverter Form gewählt ist aus der Gruppe, die aus rostfreiem Stahl, Nickel, Chromnickel und Molybdän besteht. Kompositbeschichtung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daS die Beschichtung eine Oberflächen-Deckschicht im Bereich von 6,35 - 17,78 µm (250 bis 700 Mikroinch) hat. Kompositbeschichtung nach einem der Ansprüche 1 - 3, dadurch gekennzeichnet, daß das luftgehärtete Silikon in einer Zeitdauer von 16 - 24 Stunden polymerisiert wurde. Verfahren zum Aufbringen einer Kompositbeschichtung auf ein Substrat, mit den folgenden Schritten: Bereitstellen eines Substrats,
Aufbringen einer porösen Metallmatrix auf das Substrat in einer Dicke von 0,051 - 0,025 mm (0,002 - 0,0010 inch) in einem Flammsprüh-Verfahren, wobei die Metallmatrix ein Metall in gepulverter Form aufweist,
Imprägnieren eines Films aus Silikon in die Metallmatrix, um die Porosität der Matrix abzudichten, und Aushärten des in die Matrix imprägnierten Silikon,
dadurch gekennzeichnet, daß
die Metallmatrix eine Vielzahl von Vertiefungen und darin gebildeten Ebenen hat,
der Film aus Silikon die Vertiefungen der Metallmatrix füllt und sich über ihre Ebenen erstreckt, um die Matrix vollständig zu bedecken,
wobei das Aushärten des Silikon durch Lufthärtung bei Umgebungstemperaturen während einer Zeitdauer von 16 - 24 Stunden durchgeführt wird. Verfahren nach Anspruch 5, dadurch gekennzeichnet, daß die Metallmatrix durch ein Metallsprüh-Verfahren auf das Substrat aufgebracht wird. Revêtement composite pour engendrer une surface non adhésive et résistant à l'abrasion sur un substrat, ledit revêtement composite comprenant :
   une matrice métallique poreuse appliquée par pulvérisation thermique sur ledit substrat, à une épaisseur de 0,051 à 0,025 mm (0,002 à 0,010 inch), ladite matrice comprenant un métal sous forme de poudre, et
   un film de silicone imprégnant ladite matrice pour fermer la porosité de la matrice,
caractérisé en ce que
   ladite matrice métallique comporte un très grand nombre de creux et de plateaux formés dans cette matrice,
   ledit film de silicone remplit lesdits creux et s'étend au-dessus desdits plateaux de manière à recouvrir complètement ladite matrice, et
   ledit film de silicone est durci à l'air à des températures ambiantes de façon à avoir une dureté de surface atteignant 72 Rc, il conserve une stabilité thermique à une température de fonctionnement continu atteignant 204°C (400°F) et il conserve une stabilité thermique à une température de fonctionnement intermittent atteignant 260°C (500°F). Revêtement composite suivant la revendication 1, caractérisé en ce que le métal sous forme de poudre est choisi dans le groupe comprenant l'acier inoxydable, le nickel, le nickel-chrome et le molybdène. Revêtement composite suivant la revendication 1 ou la revendication 2, caractérisé en ce que ledit revêtement présente un fini de surface dans la plage de 6,35 à 17,78 µm (250 à 700 micro-inches). Revêtement composite suivant l'une quelconque des revendications 1 à 3, caractérisé en ce que ledit silicone durci à l'air a été polymérisé pendant une durée de 16 à 24 heures. Procédé d'application d'un revêtement composite à un substrat, comprenant les opérations de :
   préparation d'un substrat,
   application d'une matrice métallique poreuse audit substrat, à une épaisseur de 0,051 à 0,025 mm (0,002 à 0,0010 inch) par un traitement de pulvérisation à la flamme, ladite matrice métallique comprenant un métal sous forme de poudre,
   imprégnation d'un film de silicone dans ladite matrice métallique , pour fermer la porosité de ladite matrice, et
   durcissement dudit silicone imprégné dans la dite matrice,
caractérisé en ce que
   ladite matrice métallique comporte un très grand nombre de creux et de plateaux formés dans cette matrice,
   ledit film de silicone remplit lesdits creux de ladite matrice métallique et s'étend au-dessus desdits plateaux de manière à recouvrir complètement ladite matrice,
   ledit durcissement dudit silicone étant effectué par durcissement à l'air à température ambiante pendant une durée de 16 à 24 heures. Procédé suivant la revendication 5, caractérisé en ce que ladite matrice métallique est appliquée audit substrat par une technique de pulvérisation de métal.