Title of Invention	COMPONENT, IN PARTICULAR HYDRAULIC COMPONENT, MADE OF COMPOSITE MATERIAL AND METHOD FOR MAKING SAME
Abstract	The invention concerns a component (11) such as a hydraulic component, made of composite material with organic matrix and reinforcing fibres (22-24), coated at least locally with a protective or metal reinforcement or metal-based layer. It comprises metal or metal-based fibres (21), said layer being formed by electrolytic deposition on said metal or metal-based fibres.

Full Text

COMPONENT, IN PARTICULAR HYDRAULIC COMPONENT, MADE OF COMPOSITE MATERIAL AND METHOD FOR MAKING SAME The invention relates to a component, such as a hydraulic component, made of composite material with organic matrix and reinforcing fibers, and to a method for making such a component. Hydraulic component is understood to mean any member capable of interacting with a flow of water and, for example, a Pelton type turbine bucket, a guide vane for a flow, a Kaplan type turbine blade or a Francis type turbine wheel. It is known, for example from WO-A-99/49213 or from EP-A-0 900 283, to make the buckets of a Pelton turbine wheel from composite plastics material. In effect, composite materials with organic matrix present good mechanical properties, essentially due to the weaving of the reinforcing fibers. However, such materials are difficult to exploit when they work in an environment where they are subjected to abrasion, shocks or erosion by the solid elements present, for example, in the flow in which they bathe. For example, in the case of a Pelton turbine used in a fall of which the water is considerably laden with inorganic matter, damage of the organic matrix and the carbon reinforcing fibers is very rapid, with the result that the life duration of the buckets is short. Similar problems are raised with other components which are subjected to difficult conditions of use. It is known to attempt to protect such pieces or components by applying a metal-based protective or reinforcing layer on such components. The deposits obtained present an adherence essentially resulting from the difference in surface energy between the material constituting the component and that constituting the protective layer. In practice, this proves insufficient and a considerable risk exists of untimely disconnection of the protective layer with respect to the component on which it is applied, with risks of damage of an industrial installation and wear and tear of the component of composite material, which is in that case very rapid. In particular, such a type of deposit is not applicable to hydraulic components. It is a more particular object of the invention to overcome these problems by proposing a component made of composite material which is efficiently protected against shocks and abrasion. In this spirit, the invention concerns a component, particularly a hydraulic component, made of composite material with organic matrix and reinforcing fibers, this component being coated at least locally with a metal or metal-based protective layer, characterized in that it comprises metal or metal-based fibers, the protective or reinforcing layer being formed by electrolytic deposition on these metal or metal-based fibers. Thanks to the invention, it is possible to have an intimate attachment between the matter of the protective or reinforcing layer and the matter of the fibers, insofar as the couple of materials chosen, for the metal or metal-based fibers on the one hand, and the protective layer on the other hand, is compatible with an electrolytic deposit. In fact the electrolytic deposit probably makes it possible to obtain a chemical bond between the material of the reinforcing fibers and the material of the protective layer, which avoids the risks of untimely detachment of the protective layer. In particular, the rigidity of the attachment obtained does not depend on the radii of curvature of the component in the zones where the protective or reinforcing layer is affixed, which makes it possible to envisage deposits on sharp edges, such as median edges of the buckets of a Pelton turbine. Bending tests have make it possible to show that the rupture of a component according to the invention occurs by disconnection of the mat or fabric of reinforcing fibers and of the organic matter, before the separation between the protective layer and the substrate on which it is affixed. According to advantageous aspects of the invention, the component incorporates one or more of the following characteristics: - The metal or metal-based fibers are essentially disposed in the vicinity of the surface of the component intended to be coated with the protective reinforcing layer. In effect, it is at the level of the surface of the component which constitutes the substrate that the attachment must occur. - The material of the metal or metal-based fibers comprises copper, aluminium, or an alloy of these metals and/or other metal elements. - The material of the protective or reinforcing layer comprises nickel cobalt, copper, other metal elements and/or alloys of these elements. - The component in question is a hydraulic component. The invention also relates to a method for making a component as described previously and. more specifically, to a method which comprises steps consisting in: - using, in at least certain zones of the component, metal or metal-based fibers, and - proceeding with an electrolytic deposit of the protective or reinforcing layer on these metal or metal-based fibers. According to advantageous aspects of the invention, the method incorporates one or more of the following characteristics: - It consists in insulating the reinforcing fibers of the component located in zones other than those including metal or metal-based fibers before proceeding with the electrolytic deposit. This makes it possible to define with high precision the geometry of the protective or reinforcing layer. In particular, it may be provided to insulate the fibers, other than the metal or metal-based fibers, by application of an insulating varnish. - A metallic element is applied by a "plasma" type deposit, on the protective or reinforcing layer after its deposit. This aspect of the invention takes advantage of the fact that the attachment obtained between the above-mentioned layer and the component or substrate is sufficiently intense to make it possible to support added elements. - Use is made, for the electrolytic bath, of a solution of metal compounds including nickel at a temperature of about 6O°C with a nickel-based counter-electrode and a current density of the order of 4 A/dm2, while the reinforcing fibers on which the deposit is effected are made of a material comprising copper. The invention will be more readily understood and other advantages thereof will appear more clearly in the light of the following description of two forms of embodiment of a hydraulic component in accordance with its principle, given solely by way of example and made with reference to the accompanying drawings, in which: Figure 1 is an exploded view in perspective of a Pelton turbine bucket according to the invention. Figure 2 is an exploded view, on a larger scale, of detail II in Figure 1, during a first step of making the bucket of Figure 1. Figure 3 is a section along line in-HI in Figure 1, during a second step of making this bucket, and Figure 4 is a plan view of a fabric of reinforcing fibers used in a bucket in accordance with a second form of embodiment of the invention. The bucket 1 shown in Figures 1 to 3 is intended to be mounted on the rim (not shown) of a Pelton turbine wheel. This bucket 1 is constituted by a first skin 11 forming its pressure face and by a second skin 12 forming its suction face, these skins being made of composite materials with a matrix based on epoxide, polyester, vinylester, urethane, polyamide or poly-ether-ether-ketone resin and reinforcing fibers based on carbon, for example, on the essential of their surface. These fibers are in the form of a resin-impregnated fabric. The geometry of the skins 11 and 12 is such that they define therebetween a volume in which are arranged rigidifying ribs 13. 14 denotes the median edge of the bucket 1 which is formed by the skin 11. This edge is subjected to intense efforts of friction which are variable depending on the quality of the water used to rotate the Pelton turbine. This edge is also subjtcted to shocks as the water may be laden with debris of relatively large size. In accordance with the invention, a layer 15 for protecting and reinforcing the edge 14 is provided on the skin 11. The layer 15 is formed by an electrolytic deposit localized on the skin 11. For this deposit to lead to an intimate attachment of the layer 15 on the edge 14, and as it more particularly visible in Figures 2 and 3, where the spaced apart relationship of the fibers is exaggerated with respect to reality, the skin 11 comprises, at the level of the edge 14, reinforcing fibers 21 made of copper while, in the rest of its surface, the skin 11 is reinforced by carbon fibers. In fact, the copper reinforcing fibers 21 are woven together and form a fabric 23 constituting the upper or outer layer of the skin 11 in the zone of the edge 14, while fabrics 24 of carbon fibers are superposed in the rest of the thickness of the skin 11 and beneath the fabric 23 at the level of the edge 14. In this way, the fibers 21 are grouped together in the vicinity of the outer surface S of the skin 11, in the zone of the edge 14. According to a variant of the invention (not shown), the assembly of the reinforcing fibers used at the level of the edge 14 might be copper fibers, in which case a plurality of layers of the type of fabric 23 would be superposed. According to another variant of the invention (not shown), mats of non-woven fibers might be used in place of the fabrics 23 and 24. As shown in Figure 4 for a second form of embodiment, it is also possible to provide that the metal fibers 21 extend in one direction of the fabric 23. for example, that they constitute the warp threads thereof over a part of its width, while the weft threads are constituted by carbon threads. The carbon weft threads 22 extend both over a part 23A of the fabric 23 in which they are woven with copper warp threads 21 and on parts 23B of the fabric 23 in which they are woven with warp threads 26 made of carbon. In this way, the outer layer of the skin 11 of the bucket 1 is itself continuous, only a part thereof being adapted to the electrolytic deposit. In that case, the width of the part 23A is determined as a function of the desired width of the layer 15. The continuous nature of the fabric 23 ensures a good anchorage of the threads 21 in the structure of the skin 11. In Figure 4, the spaced apart relationship of the fibers is also exaggerated in order to improve understanding of the drawing. EXAMPLES When the skin 11 has been moulded, there is deposited on the parts 16 of this skin comprising only carbon fibers 22, namely bands 24A in the first form of embodiment or parts 23B in the second, a layer 25 of insulating varnish, before cleaning and degreasing the layers of fabrics 23 comprising fibers 21 and immersing the skin 11 in a bath of metal compounds with the following distribution: NiCl 50 g/I, NiSOa 150 g/1, H,PO, 8 2/1, H3POi 26.3 ml/1 This bath is maintained at a temperature of about 6O°C. A nickel counter-electrode and depassivating elements are used and a current is applied with a density of about 4 A/dm2, which makes it possible to obtain on the fabric 23 the formation of the layer 15 essentially with nickel, the layer obtained having a Vickers hardness of the order of 150 HV. Satisfactory results have also been obtained with cobalt ions in solution in the aforementioned bath, in which case the deposit obtained is of Ni-Co type. Of course, other couples of metals may be envisaged for, on the one hand, the metal fibers 21 and. on the other hand, the electrolyte bath, i.e. the protective or reinforcing layer 15. In particular, it may be provided to use the following materials: - for the metal fibers: copper, aluminium, alloys of these metals or other metallic elements - for the protective or reinforcing layer: copper, nickel, cobalt or other metallic elements or alloys of these elements. The invention is not limited to a Pelton turbine bucket and may be carried out with a Kaplan turbine blade, with a guide Wade, particularly at the level of their respective leading edges, and with a Francis turbine wheel, particularly at the level of the leading edges of the blades and at the level of the exposed edges of the belt and of the ceiling. In all cases, the zones to be protected are zones with small radii of curvature, which is not detrimental in view of the intimate attachment obtained by electrolytic deposit. Other mechanical components may be made thanks to the invention, such as for example turbine fins. Whatever the type of component in question, the intimate attachment obtained between the protective or reinforcing layer and the substrate makes it possible to envisage supporting elements added on this layer by so-called "plasma" deposit, of the plasma spray type, PVD ("Power Vapor Deposition" or deposit by physical method), CVD ("Chemical Vapor Deposition" or deposit by chemical method), etc.. In effect, the localized elevation of temperature allowing the deposit is compatible with the nature of the material of the layer, without risk of damage of the component made of composite materials. This additional deposit with plasma makes it possible to increase the heat protection, the protection against erosion or corrosion, and even the mechanical protection. CLAIMS 1. Component, particularly hydraulic component, made of composite material with organic matrix and reinforcing fibers, said component being coated at least locally with a metal or metal-based protective layer, characterized in that it comprises metal or metal-based fibers (21), said layer (15) being formed by electrolytic deposition on said metal or metal-based fibers. 2. Component according to Claim 1, characterized in that said metal or metal-based fibers (21) are essentially disposed in the vicinity of the surface (S) of said component (1) intended to be coated with said layer. 3. Component according to one of the preceding Claims, characterized in that the material of said metal or metal-based fibers (21) comprises copper, aluminium, or an alloy of these metals and/or other metal elements. 4. Component according to one of the preceding Claims, characterized in that the material of said layer (15) comprises nickel, cobalt, copper or other metal elements and/or alloys of these elements. 5. Component according to one of the preceding Claims, characterized in that it is question of a hydraulic component. 6. Method for making a component, such as a hydraulic component, made of composite material with organic matrix and reinforcing fibers and coated at least locally with a metal or metal-based protective or reinforcing layer, characterized in that it comprises steps consisting in: - using, in at least certain zones (14) of said component (1), metal or metal-based fibers (21), and - proceeding with an electrolytic deposit of said layer (15) on said metal or metal-based fibers. 7. Method according to Claim 6, characterized in that it consists in insulating the reinforcing fibers (22) of said component (1) located in zones (16) other than that/those (14) including metal or metal-based fibers (21) before proceeding with said electrolytic deposit (15). 8. Method according to Claim 7, characterized in that it consists in insulating said fibers (22), other than the metal or metal-based fibers (21), by application of an insulating varnish (25). 9. Method according to one of Claims 6 to 8, characterized in that it consists in applying, by a "plasma'1 type deposit, a metal element on said layer (15) after the electrolytic deposit of said layer. 10. Method according to one of Claims 6 to 9, characterized in that it consists in using, for the electrolytic bath, a solution of metal compounds including nickel at a temperature of about 6O°C with a nickel-based counter-electrode and a current density of the order of 4 A/dm2, while the reinforcing fibers (21) on which the deposit is effected are made of a material comprising copper. 11. A component substantially as herein described with reference to the accompanying drawings.

Documents:

810-chenp-2003-abstract.pdf

810-chenp-2003-claims filed.pdf

810-chenp-2003-claims granted.pdf

810-chenp-2003-correspondnece-others.pdf

810-chenp-2003-correspondnece-po.pdf

810-chenp-2003-description(complete)filed.pdf

810-chenp-2003-description(complete)granted.pdf

810-chenp-2003-drawings.pdf

810-chenp-2003-form 1.pdf

810-chenp-2003-form 26.pdf

810-chenp-2003-form 3.pdf

810-chenp-2003-form 5.pdf

810-chenp-2003-other document.pdf

810-chenp-2003-pct.pdf

abs-810-chenp-2003.jpg