NL2014687A

NL2014687A - Object comprising a fiber reinforced plastic and a ceramic material.

Info

Publication number: NL2014687A
Application number: NL2014687A
Authority: NL
Inventors: Hubert Christiaan Coumans Roeland
Original assignee: Hubert Christiaan Coumans Roeland
Priority date: 2015-04-21
Filing date: 2015-04-21
Publication date: 2016-10-24
Also published as: NL2014687B1

Abstract

The invention is directed to an object comprising a. a fiber reinforced plastic and b. a ceramic material, wherein the ceramic material is prepared by plasma electrolytic oxidation of a metal selected from the group consisting of aluminium, titanium and magnesium. The invention is further directed to a process for the preparation of the object wherein the process comprises the following steps a. Providing a metal selected from the group consisting of aluminium, titanium and magnesium and a fiber reinforced plastic or a precursor of a fiber reinforced plastic, b. Treating, at least partially, the metal with plasma electrolytic oxidation to provide a ceramic material, c. Attaching the ceramic material with a resin to the fiber reinforced plastic or the precursor of a fiber reinforced plastic, d. Curing the resin to provide an object comprising a fiber reinforced plastic coated with a ceramic materia!.

Description

OBJECT COMPRISING A FIBER REINFORCED PLASTIC AND A CERAMIC MATERIAL

The invention is directed to an object comprising a fiber reinforced plastic and a ceramic material and to a process for the preparation of the object.

It is known to make objects made of fiber reinforced plastics. These objects are used where light and strong materials are required, for example car parts or machine parts. The problem of many of these parts is a low wear resistance. This becomes visible when the parts are moving and are in contact with other parts.

This problem is solved according to the prior art by the application of a metallic or ceramic layer on the fiber reinforced plastic on the side that is in contact with other parts.

The ceramic or metallic layer can be applied by thermal spray techniques, like for example, plasma spraying or flame spraying.

Thermal spay processes are for example described in EP0514640, EP1129787, EP1264708 and W02006/089519. EP0514640 describes a process for the application of a metallic or ceramic layer on an object of fiber reinforced plastic. The layer is applied by thermal spraying after the surface of the fiber reinforced plastic is treated to free particles in the surface layer of the fiber reinforced plastic that is said to improve the adhesion between the fiber reinforced plastic and the metallic or ceramic layer after spraying. EP1129787 describes coatings on fiber reinforced composites. The coating comprises a first polymeric layer free of fibers and particulate, a second polymeric layer containing a polymeric matrix and a particulate and a thermally sprayed material coats the second polymeric layer. EP1264708 describes a process to apply a coating on a rotating body. The rotating body is coated with a thermoset or thermoplastic layer comprising 5-80 vol% metal particles or ceramic particles. This layer is sanded and thereafter a metal layer or ceramic layer is applied thereon by thermal spraying. W02006/089519 describes a coated member that is made of carbon fiber reinforced plastic. This coated member comprises an adhesive layer made of a ductile material, that is selected among the group comprising copper, nickel, iron, lead and tin, and a hard metal or oxide ceramic layer which is applied to the adhesive layer.

The above references all describe that the adhesion between the fiber reinforced plastic and the ceramic layer is important and is difficult to achieve.

Object of the invention is to improve adhesion between the object made of fiber reinforced plastic and the ceramic material.

It has been surprisingly discovered that the adhesion can be significantly improved in an object comprising a. a fiber reinforced plastic and b. a ceramic material, wherein the ceramic material is prepared by plasma electrolytic oxidation of a metal selected from the group consisting of aluminium, titanium and magnesium.

The object has the advantage that an excellent adhesion exists between the fiber reinforced plastic and the ceramic material. The ceramic material in the object is hardly porous and forms a closed layer resulting in an excellent adhesion.

Another advantage of the objects according to the invention is that the wear resistance of the object is improved by the ceramic material that forms a very hard surface on the object. A further advantage of the objects according to the invention is that the ceramic material is an electrical insulator and protects the object from galvanic corrosion.

The object according to the invention comprises a fiber reinforced plastic. The plastic in the fiber reinforced plastic can be a thermoset resin composition but also a thermoplastic resin composition. Examples of resins are epoxies, polyesters, vinyl esters, phenolic resins or nylons.

Preferably, the fiber reinforced plastic comprises a thermoset resin composition.

The fibers in the fiber reinforced plastic can, for example, be chosen from carbon fibers, glass fibers, silicon carbide fibers, and fibers of many other oxides, carbides, aramid e.g. Kevlar® and Twaron®, ultra-high-molecular-weight polyethylene (UHMWPE) and other fiber materials. Preferably, the fiber reinforced plastic comprises carbon fibers.

The fibers may be very long and may be positioned in specific patterns or can be relatively short and randomly dispersed. When long fibers are positioned in specific patterns, they can be aligned in a single direction or positioned in patterns designed to give two or three dimensional strength to the fiber reinforced plastic. For example, from the fibers an unidirectional sheet can be created. These sheets can be layered onto each other in a quasi-isotropic layup, e.g. 0°, +60° or -60° relative to each other. From the fibers also a bidirectional woven sheet can be created.

The mechanical properties of the fiber reinforced plastic can be tailored to the specific requirements of the object. Fiber-reinforced polymers are composite materials. The composite consists of two parts: a matrix resin and a fiber reinforcement. In carbon fiber reinforced plastic the reinforcement is carbon fiber, which provides the strength. The matrix resin is preferably a thermoset resin, such as epoxy, to bind the reinforcements together. Because carbon fiber reinforced plastic consists of two distinct materials, the material properties depend on these two materials.

The properties of the object can also be affected by the type of additives introduced to the resin. The most frequently used additive is silica, but other additives such as rubber and carbon nanotubes can also be used.

The object according to the invention comprises a ceramic material. A ceramic material is an inorganic, nonmetallic solid comprising metal, nonmetal or metalloid atoms primarily held in ionic and covalent bonds. The crystallinity of ceramic materials ranges from highly oriented to semicrystalline, and often completely amorphous (e.g., glasses). When, for example, aluminium is treated with plasma electrolytic oxidation aluminiumoxide is partially converted from amorphous alumina into crystalline forms such as corundum (a-AI203).

Properties of the ceramic material are a high melting temperature, high hardness, poor conductivity, high modulus of elasticity, chemical resistance and low ductility.

In the object according to the invention the ceramic material is prepared by plasma electrolytic oxidation of a metal selected from the group consisting of aluminium, titanium and magnesium. Preferably, the metal is aluminium.

Plasma electrolytic oxidation (PEO), also known as microarc oxidation (MAO), is an electrochemical surface treatment process for generating oxide coatings on metals. It is similar to anodizing, but it employs higher potentials, so that discharges occur and the resulting plasma modifies the structure of the oxide layer. This process can be used to grow thick (tens or hundreds of micrometers), largely crystalline, oxide coatings on aluminium, titanium and magnesium.

Because of their high hardness and a continuous barrier, these coatings can offer protection against wear, corrosion or heat as well as electrical insulation. The coating is an electro-chemical conversion of aluminium, titanium or magnesium into its oxide, and grows both inwards and outwards from the original metal surface. Because it is a conversion coating, rather than a deposited coating (such as a coating formed by thermal spraying), it has excellent adhesion to the metal.

During PEO a layer of oxide is grown on the surface of the metal by the application of electrical potential, while the part is immersed in an electrolyte.

In plasma electrolytic oxidation, high potentials are applied. For example, in the plasma electrolytic oxidation of aluminium, at least 200 V must be applied. This locally exceeds the dielectric breakdown potential of the growing oxide film, and discharges occur. These discharges result in localised plasma reactions, with conditions of high temperature and pressure which modify the growing oxide. Processes include melting, melt-flow, re-solidification, sintering and densification of the growing oxide. The metal is immersed in a bath of an electrolyte, which usually is an aqueous solution comprising salts and bases. It is electrically connected, so as to become one of the electrodes in the electrochemical cell, with the other "counter-electrode" typically being made from an inert material such as stainless steel, and often consisting of the wall of the bath itself. Potentials of over 200 V are applied between these two electrodes. These may be continuous or pulsed direct current (DC) (in which case the part is simply an anode in DC operation), or alternating pulses (alternating current or "pulsed bi-polar" operation) where the stainless steel counter electrode might just be earthed.

Depending on the thickness of the metal a part or the complete metal is oxidized into a ceramic material.

The object according to the invention comprises a fiber reinforced plastic and a ceramic material. There is an excellent adhesion between the fiber reinforced plastic and the ceramic material.

The object can have any form, for example a plate, a disc, a cylinder, a cube, a block or any other form.

In the object the ceramic material is at least partially bound to the fiber reinforced plastic. Not all surfaces of the object need to be covered with the ceramic material.

Preferably, the object has a layered structure. More preferably, the object comprises a layer of carbon fiber reinforced plastic and a layer of ceramic material bound to the layer of carbon fiber reinforced plastic.

The thickness of the ceramic material is preferably more than 2 pm, more preferably more than 3 pm, most preferably more than 4 pm. The thickness of the ceramic material is preferably less than 150 pm, more preferably less than 120 pm, most preferably less than 100 pm.

Preferably, the ceramic material in the object has a thickness of 2-150 pm, more preferably a thickness of 3-120 pm, most preferably a thickness of 4-100 pm.

In a preferred embodiment the object comprises a. a layer of carbon fiber reinforced plastic, b. a layer of ceramic material and c. a layer of metal selected from the group consisting of aluminium, titanium and magnesium, wherein the layer of ceramic material is bound to the layer of carbon fiber reinforced plastic.

In this preferred embodiment the layer of carbon fiber reinforced plastic preferably has a thickness of more than 0.5 mm, more preferably of more than 0.7 mm, most preferably of more than 1.0 mm. The thickness of the layer of carbon fiber reinforced plastic is preferably less than 5 mm, more preferably less than 4 mm, most preferably less than 3 mm.

The layer of ceramic material preferably has a thickness of more than 2 pm, more preferably more than 3 pm and most preferably more than 4 pm. The thickness of the ceramic material is preferably less than 25 pm, more preferably less than 20 pm, most preferably less than15 pm.

The layer of metal preferably has a thickness of more than 0.1 mm, more preferably of more than 0.2 mm, most preferably of more than 0.3 mm. The thickness of the layer of metal is preferably less than 5 mm, more preferably less than 3 mm, most preferably less than 2 mm.

In an object according to the preferred embodiment the layer of carbon fiber reinforced plastic has a thickness of 0.5-5 mm, the layer of ceramic material has a thickness of 2-25 pm and the layer of metal has a thickness of 0.1-5 mm.

Preferably, the layer of ceramic material is present on at least one side of the layer of metal and is prepared by plasma electrolytic oxidation of the metal. In the preferred object the layer of ceramic material can be present on one or on both sides of the layer of metal. The layer of ceramic material is prepared by plasma electrolytic oxidation of the metal before the metal layer with the layer of ceramic material is brought into contact with the layer of carbon fiber reinforced plastic.

The object of the invention can be used for various applications. Especially for application where a light and wear resistant material is required. The object according to the invention can for example be an engine part, more specifically a bearing or a roller. The object can also be used where a metal part needs to be fastened to a fiber reinforced plastic to improve the adhesion between the metal part and the fiber reinforced plastic. The object can, for example, be a fiber reinforced plastic object with at least one insert comprising ceramic material.

The invention is also directed to a process for the preparation of an object, wherein the process comprises the following steps a. Providing a metal selected from the group consisting of aluminium, titanium and magnesium, and a fiber reinforced plastic or a precursor of a fiber reinforced plastic, b. Treating, at least partially, the metal with plasma electrolytic oxidation to provide a ceramic material, c. Attaching the ceramic material with a resin to the fiber reinforced plastic or the precursor of a fiber reinforced plastic, d. Curing the resin to provide an object comprising a fiber reinforced plastic coated with a ceramic material.

According to the process of the invention a fiber reinforced plastic or a precursor of a fiber reinforced plastic is provided. A precursor of a fiber reinforced plastic is a non-cured combination of fibers and resin. A precursor is, for example a non-cured resin comprising fibers or a fiber sheet or can be a fiber sheet that is provided separate from the resin and is combined during the process with the resin to form a fiber reinforced plastic.

The metal is also provided and the surface of the metal is treated, at least partially, with PEO to provide a ceramic material. The ceramic material can be brought in contact with the precursor before the resin is added to the mold or just after the resin is added to the mold. The ceramic material is attached with a resin to the fiber reinforced plastic or the precursor of the fiber reinforced plastic. A method of producing a fiber reinforced plastic object is, for example, by placing the ceramic material in a mold and layering sheets of carbon fiber cloth into the mold in the shape of the final product. The alignment and weave of the cloth fibers is chosen to optimize the strength and stiffness properties of the resulting material. To obtain the fiber reinforced plastic object the mold is then filled with resin and is cured. Curing of the resin can be obtained by treating the resin with heat, air or UV light.

For objects used in less critical areas the fiber reinforced plastic or a precursor of a fiber reinforced plastic can be manufactured by draping cloth over a mold comprising the ceramic material, with resin either pre-impregnated into the fibers (also known as pre-preg) or "painted" over it. High-performance parts using single molds are often vacuum-bagged and/or autoclave-cured, because even small air bubbles in the material will reduce strength. Further compression molding and filament winding can be used to provide the fiber reinforced plastic objects.

During the process the ceramic material is attached with a resin to the fiber reinforced plastic or the precursor of a fiber reinforced plastic. The resin is cured in the presence of the ceramic material to provide an object comprising a fiber reinforced plastic coated with a ceramic material.

In the process for the preparation of the object preferably the surface of the metal is partially treated with plasma electrolytic oxidation (PEO) to provide a ceramic material and the resin is cured to provide an object comprising a fiber reinforced plastic coated with a ceramic material bound to metal. The metal surface of the obtained object can thereafter be further treated by machining, grinding, anodisation, plasma spray coating, flame spray coating, electric-arc spray coating, cold spray coating and/or plasma electrolytic oxidation.

Although the invention has been described in detail for purposes of illustration, it is understood that such detail is solely for that purpose and variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the claims.

It is further noted that the invention relates to all possible combinations of features described herein, preferred in particular are those combinations of features that are present in the claims.

It is further noted that the term ‘comprising’ does not exclude the presence of other elements. However, it is also to be understood that a description on a product comprising certain components also discloses a product consisting of these components. Similarly, it is also to be understood that a description on a process comprising certain steps also discloses a process consisting of these steps.

Claims

An article comprising a. A fiber-reinforced plastic and b. a ceramic material, wherein the ceramic material is made by plasma electrolytic oxidation of a metal selected from the group consisting of aluminum, titanium and magnesium.

The article of claim 1, wherein the fiber-reinforced plastic comprises a thermosetting resin composition.

The article of claim 1 or 2, wherein the fiber-reinforced plastic comprises carbon fibers.

The article of any one of claims 1 to 3, wherein the ceramic material is at least partially bonded to the fiber-reinforced plastic.

The article of any one of claims 1 to 4, wherein the article comprises a layer of carbon fiber-reinforced plastic and a layer of ceramic material bonded to the layer of carbon fiber-reinforced plastic.

The article of any one of claims 1 to 5, wherein the ceramic material has a thickness of 2-150 µm.

The article of any one of claims 1 to 6, wherein the article comprises a. A layer of carbon fiber-reinforced plastic, b. a layer of ceramic material and c. a layer of metal selected from the group consisting of aluminum, titanium and magnesium, wherein the layer of ceramic material is bonded to the layer of carbon fiber-reinforced plastic.

The article of claim 7, wherein the layer of carbon fiber-reinforced plastic has a thickness of 0.5-5 mm, the layer of ceramic material has a thickness of 2-25 µm and the layer of aluminum has a thickness of 0 , 1-5 mm.

The article of claim 7, wherein the layer of ceramic material is present on at least one side of the layer of metal and is made by plasma electrolytic oxidation of the metal.

The article of any one of claims 1-9, wherein the article is a machine part.

The article of claim 10, wherein the article is a bearing or a roller.

A method of making an article according to any of claims 1 to 11, wherein the method comprises the steps of a. Providing a metal selected from the group consisting of aluminum, titanium and magnesium and a fiber-reinforced plastic or a precursor of a fiber-reinforced plastic, e.g. treating, at least in part, the metal with plasma electrolytic oxidation to obtain a ceramic material, c. attaching the ceramic material with a resin to the fiber-reinforced plastic or to the precursor of the fiber-reinforced plastic, d. curing the resin to obtain an article comprising the fiber-reinforced plastic coated with the ceramic material.

The method of claim 12, wherein the metal is partially treated with plasma electrolytic oxidation (PEO) to obtain a ceramic material and the resin is cured to obtain an article comprising a fiber-reinforced plastic covered with a layer of the ceramic material bonded on the metal.

The method of claim 13, wherein the metal surface of the article is further treated by machine machining; grinding; anodizing; coated by plasma spraying, flame spraying, electric arc spraying, cold spraying; and / or by plasma electrolytic oxidation.