MX2008005144A - Method for coating a component - Google Patents

Abstract

The invention relates to a method for coating a component consisting of a fibre-reinforced composite material. According to said method:a) a composite consisting of organic and metallic parts is applied to a surface of the component to be coated, as an adhesive layer, by means of thermal spraying;b) a layer predominantly comprising metallic parts is applied to the adhesive layer, as an intermediate layer, by means of thermal or kinetic spraying;and c) a functional covering layer consisting of metal, a metal-carbide composite, oxide ceramics or mixtures of said materials is applied to the intermediate layer by means of thermal or kinetic spraying.

Description

METHOD FOR COVERING A COMPONENT Description of the invention The invention relates to the generation of functional surfaces in fiber-reinforced composite materials by the application of thermal and kinetic spraying, where the protection of the member's surface against wear, mechanical damage and adhesions is considered, as well as an improvement of the sheet release (release behavior) are of particular importance. Fiber reinforced composites, particularly those comprising a polymer matrix as well as carbon fiber reinforced polymers, allow the production of members having extraordinary mechanical and physical characteristics, such as low density, high tensile strength and torsion , and a large modulus of elasticity or a high rigidity, respectively. A multiplicity of high strength fiber materials can be used, including carbon fibers, glass fibers, silicon carbide fibers as well as many other oxides, carbides and other materials. Also a large multiplicity of polymeric materials can be used, including phenolic resins, epoxy resins and many other materials. The fibers can be very long and can be placed in specific patterns, or they can be relatively short and distributed randomly. When the long fibers are placed in specific patterns, they can be oriented in a single direction, or they can be placed in patterns that are designed to impart a two- or three-dimensional force to the fiber-reinforced composite material. Thus, the mechanical characteristics of the structure of the fiber-reinforced composite material can be adapted to the specific requirements of a member. Unfortunately, the surfaces of the fiber reinforced composites have a low wear resistance, particularly against adhesive, abrasive and erosive wear, and the adhesive and melt characteristics thereof are scarce for many applications, such as in the paper industry . In addition, they are frequently susceptible to oxidation and other types of corrosion, require thermal protection, and do not have the required optical and electrical characteristics and the like. Therefore, the utility of fiber-reinforced composites is limited in many applications or requires the use of metallic or ceramic inserts in the regions that are exposed to contact with other members or materials and are thus exposed to increasing wear. However, the use of rollers made of fiber-reinforced composites is of particular interest in the printing, paper and lamination industry because they are substantially lighter and more rigid and thus can be controlled more easily and with more security that the rollers made for example of steel. Due to their lower inertia they also need less energy and time to accelerate and brake. This allows cost savings not only in the control and assembly but also in the operation. To provide the working surfaces of the rollers with the necessary characteristics, the rollers comprise a coating of metals, ceramics or carbides or mixtures thereof with plastic, whose coating offers the required wear resistance and other necessary characteristics. By using the thermal spray processes, a large multiplicity of metallic and ceramic layers, cermet layers, ie carbide particles inserted in a metal matrix, as well as some polymeric coatings can be produced. The family of thermal spray processes includes detonation spraying (among others Super D-GunTM), high-speed fire sprinkling and variations thereof, for example air-fuel spraying, plasma spraying, sprinkling with fire and electric spray. In most thermal coating processes, the spray material is heated in the form of powder, wire or rods to a temperature corresponding to or slightly above the melting point thereof, and the droplets or melting particles of the material are accelerated in a gas stream. The droplets are directed to the surface of the substrate to be coated, where they adhere, solidify and form a continuous layer having a laminar structure. In the case of the batch spray process of discontinuous operation, the layer is developed by rigidly joined individual spray nozzles overlapped. Such processes are known to the expert and are described in detail in numerous documents. Although many attempts have been made to apply thermal spray coatings based on metal, ceramic or carbide directly on the surfaces of fiber reinforced composites, generally only very poor adhesion of the layer can be obtained. Frequently the layers do not adhere to the fiber reinforced substrate or previously formed flakes during the deposition of a small layer thickness. Commonly the surface of the limb becomes roughened before the application of the thermal spray layer to improve adhesion. Primarily the frizz is effected by altering the surface with corundum. Alteration with corundum or other types of frizz of the surfaces to be coated, however, can result in unacceptable erosion of the polymer matrix combined with an exposure of the fibers. The latter can strongly deteriorate the characteristics of the layer. This and other problems, for example, become apparent when applying the process described in US-A-5,857,950. In this case the surface of a carbon fiber roller is altered with sand, with which a zinc coating is applied as a thermal protection. After again with the alteration with the roll sand now coated with zinc, an adhesive coating is applied, such coating may consist of a mixture of bronze, aluminum and polyester. Subsequently, the adhesive coating is altered with sand, and a ceramic spray coating is applied and etched. This process has proven to be unacceptable. An alternative process is described in EP 0 514 640 B 1. In this case, at the beginning a layer consisting of a mixture of a synthetic resin and metal particles dispersed therein is produced on the surface of a fiber-reinforced composite material. During curing of this layer, the surface is turned to expose the dispersed particles, so that the particulate material can be chemically combined with the material of an outer layer that is thermally sprayed on the first layer. Despite the fact of the limited success that can be achieved with this process, the mixture of synthetic resin and particulate material can not adhere properly to the composite material and tends to form in the superficial globules of the material, so it does not adapt for a commercial production According to DE 100 37 212 A1, an adhesive surface is applied to a plastic surface by a thermal spray process, wherein this adhesive surface can consist of zinc, zinc alloy, alloys and / or aluminum materials, such as nickel-aluminum alloys, which react exothermically during the course of the spraying process. Subsequently, a functional layer produced in addition by a thermal spray process is applied to the adhesive surface. Furthermore, EP 1 129 787 B 1 discloses a coating process in which a substrate of fiber reinforced composite material is coated with a first layer containing only the polymer, a second layer of a polymer / metal mixture and subsequently a thermal spray coating. To obtain a sufficient bond strength between the layers, the polymeric materials suitable for the first two coating layers must be selected. The basic problem of the present invention is to provide the coated fiber-reinforced composite materials in which the adhesion of the coated layers to the composite material is further improved. The present invention relates particularly to the object of improving the wear resistance of fiber reinforced plastics by combining two or more thermally or kinetically sprayed layer systems. According to the invention this problem is solved based on the principle of a compound containing organic and metallic components applied by means of thermal spray as an adhesive layer to the surface of the fiber-reinforced plastic material; the thermally or kinetically sprayed layer comprising predominantly metallic components is applied to the adhesive layer as an intermediate layer; and the thermally or kinetically sprayed functional cover layer consisting of metal, CERM ET (a metal-carbide composite), oxide ceramic or mixtures of the materials or mixtures thereof with plastic material, is applied to the intermediate layer. A mixture of two or more different materials can be used in the spraying of the metal-plastic compound that is applied as an adhesive layer. Instead of the use during the process of spraying two or more partial streams, the material sprayed in the form of powder or wire by itself may consist of the material compound. The purpose of the aforementioned adhesive layer is to provide via its plastic component an improved bond to the matrix of the fiber-reinforced raw material, and simultaneously ensure a better fusion of any exposed fiber, which is also favorable for the adhesion of the layers . The purpose of the metallic components of the adhesive layer is to allow a bond to the metal intermediate layer to be applied later. This intermediate layer is essential for the final use of the functional cover layer. It serves as a stable base for the very fragile wear-resistant cover layer and simultaneously provides a moderate equalization of the modulus of elasticity of the adhesive layer and the cover layer. In addition, the metallic intermediate layer provides a uniform distribution and dissipation of the heat introduced during the additional coating of the member by, for example, high-speed fire sprinkling or detonation sprinkling. Without sufficient heat dissipation, local evaporation of the organic binder from the substrate body can occur, which would result in separation of the entire layer system. The currently suggested process allows the production of coated members of the fiber reinforced composite material that also adapt to high dynamic loads, as well as members that have a large layer area. Preferred embodiments of the invention continue from the sub-claims. Preferably the organic component of the adhesive layer, for example polyester, amounts between 5 and 60%, more preferably between 20 and 50%, and most preferably between 30 and 40%. The metal component of the adhesive layer, for example aluminum, copper or nickel, preferably amounts between 40 and 90%, and more preferably between 60 and 80%. The thickness of the adhesive layer is preferably between 0.1 and 2 millimeters, more preferably between 0.1 and 1 millimeter, and most preferably between 0.2 and 0.4 millimeters. In a particularly preferred embodiment an adhesive layer 0.2 millimeters thick is applied by spraying plasma and consists of a metal-polyester compound. In another particularly preferred embodiment, the metal layer having a thickness of approximately 0.1 to 1 millimeter is sprayed by a thermal spray process onto the adhesive layer. In one embodiment, the thickness of the intermediate layer is between 0.5 and 2 millimeters. Before applying the cover layer, the intermediate layer can be turned, for example by grinding or turning it, to level the inequality caused by the stages of previous processes. It is favorable to apply the metal intermediate layer by a method that does not involve combustion, such as arc spraying, plasma spraying or kinetic spraying, to keep the heat input into the raw material of the fiber reinforced plastic as low as possible.

It is also favorable to use for the intermediate layer a metallic material having a ductility as high as possible. In another embodiment, the intermediate layer already consists of a composite of metal and hard material, for example a layer composed of aluminum-alumina sprayed kinetically, to provide an increase in strength. When the layer of the fiber-reinforced material particularly aims at increasing the wear resistance, the functional cover layer of the layer system preferably consists of ceramic oxide (for example chromium) or CERMET (metal-carbide compound, for example). example tungsten carbide particles inserted in a metallic cobalt matrix).

Claims (7)

1. Method for coating a fiber reinforced composite member, characterized in that (a) at first a compound consisting of organic and metallic components is applied by means of thermal spray as an adhesive layer to a surface of the member to be coated; (b) a layer comprising predominantly metal components is applied by means of thermal or kinetic spraying as an intermediate layer to the adhesive layer; and (c) a functional cover layer consisting of metal, a metal-carbide composite, ceramic oxide or mixtures thereof, is an intermediate layer applied by means of thermal or kinetic spraying. Method according to claim 1, characterized in that the organic component of the adhesive layer is between 5 and 60%, preferably between 20 and 50%, and more preferably between 30 and 40%. Method according to claim 1, characterized in that the metal component of the adhesive layer is between 40 and 90%, and preferably between 60 and 80%. Method according to any of the preceding claims, characterized in that the thickness of the adhesive layer is between 0.1 and 2 millimeters, preferably between 0.1 and 1 millimeter, and more preferably between 0.2 and 0.4 millimeters. Method according to any of the preceding claims, characterized in that the metal component of the intermediate layer amounts to 60% or more. Method according to any of the preceding claims, characterized in that the thickness of the intermediate layer is between 0.1 and 2 thousand meters, preferably between 0.2 and 1 thousand, and more preferably between 0.3 and 0.6 millimeters. Method according to any of the preceding claims, characterized in that the intermediate layer is turned before applying the cover layer.