FR2817284A1 - PART, IN PARTICULAR HYDRAULIC COMPONENT, OF COMPOSITE MATERIAL AND METHOD FOR MANUFACTURING SUCH A PART - Google Patents

Abstract

A part (11) such as a hydraulic component, made of a composite material with an organic matrix and reinforcing fibers (22-24), is coated at least locally with a protective or reinforcing layer, metallic or based on metal. It comprises metallic or metal-based fibers (21), the aforementioned layer being formed by electrolytic deposition on these metallic or metal-based fibers.

Description

The invention relates to a part, such as a hydraulic component, in

  composite material with organic matrix and reinforcing fibers, and a method of manufacturing such a part. The term “hydraulic component” means any member capable of interacting with a flow of water and, for example, a Pelton type turbine trough, a director for a flow, a Kaplan type turbine blade or a

Francis type turbine wheel.

  It is known, for example from WO-A-99 / 49,213 or from EP-A-0 900 283 to produce the buckets of a Pelton turbine wheel in composite plastic material. Indeed, organic matrix composite materials have good mechanical properties due, essentially, to the weaving of

  reinforcement. However, these materials are difficult to use.

  when they work in an environment where they are subject to abrasion, shock or erosion by solid elements present, for example, in the flow in which they are immersed. For example, in the case of a Pelton turbine used in a chute whose water is heavily loaded with mineral matter, the damage to the organic matrix and to the carbon reinforcing fibers is very rapid,

  so the lifespan of the buckets is short.

  Similar problems arise with other parts

  which are subject to difficult conditions of use.

  It is known to try to protect such parts or components by applying a protective or reinforcing layer based on metal on such parts. The deposits obtained have an adhesion resulting, essentially, from the difference in surface energy between the constituent material

  of the part and that constituting the protective layer.

  In practice, this proves to be insufficient and there is a significant risk of untimely separation of the protective layer from the part to which it is applied,

  with risk of damage to an undue installation

  trielle and then very rapid wear of the composite part. In particular, such a type of deposit is not

  applicable to hydraulic components.

  It is to these problems that the invention more particularly intends to remedy by proposing a part made of composite material which is effectively protected against impact and abrasion. In this spirit, the invention relates to a part, in particular a hydraulic component, made of a composite material with an organic matrix and reinforcing fibers, this part being coated at least locally with a protective layer of metal or based on metal, characterized in that that it comprises metallic or metal-based fibers, the protective or reinforcing layer being formed by deposition

  electrolytic on these metallic or metal-based fibers.

  Thanks to the invention, it is possible to have an addiction

  intimate chage between the material of the protective or reinforcing layer and the material of the fibers insofar as the couple of material chosen, for metallic or metal-based fibers on the one hand and the protective layer on the other , is compatible with electrolytic deposition. In fact, the electroplating 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

  risk of inadvertent release of the protective layer.

  In particular, the rigidity of the attachment obtained does not depend on the radii of curvature of the part in the areas where the protective or reinforcing layer is affixed, which makes it possible to envisage deposits on sharp edges, such as middle edges of the buckets of a Pelton turbine. Bending tests have made it possible to show that the rupture of a part in accordance with the invention takes place by separation 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 part incorporates one or more of the following characteristics: - The metallic or metal-based fibers are arranged, essentially, in the vicinity of the surface of the part intended to be coated with the protective reinforcement layer. Indeed, it is at the surface of the

  part which constitutes the substrate which the accretion must take place

  chage. - The material of metallic or metal-based fibers comprises copper, alumimium, or an alloy of these metals and / or other metallic elements. - The material of the protective or reinforcing layer comprises nickel, cobalt, copper, other metallic elements and / or alloys of these elements.

  - The part in question is a hydraulic component.

  The invention also relates to a manufacturing method

  of a part as previously described and, more specifically

  only a process which comprises steps consisting in: - using, in at least certain areas of the room, metallic or metal-based fibers and - carrying out an electrolytic deposition of the protective or reinforcing layer on these metallic fibers

or based on metal.

  According to advantageous aspects of the invention, the method incorporates one or more of the following characteristics: - It consists in isolating the reinforcing fibers from the part located in areas other than those including metallic or metal-based fibers before proceeding to electroplating. This allows the geometry of the protective or reinforcement layer to be defined with good precision. In particular, it is possible to isolate the fibers, other than metallic or metal-based fibers,

  by applying an insulating varnish.

  - A "plasma" type deposit is applied,

  metallic element on the protective or reinforcing layer

  ment after its deposit. This aspect of the invention takes advantage of the fact that the bonding obtained between the aforementioned layer and the part or substrate is sufficiently intense to allow

  to support reported elements.

  - For the electrolytic bath, a solution of metallic compounds including nickel is used at a temperature of approximately 60 C with a nickel-based counter electrode and a current density of the order of 4 A / dm2, then that the reinforcing fibers on which the

  deposit are made of a material comprising copper.

  The invention will be better understood and other advantages thereof will appear more clearly in the light of the

  description which follows of two embodiments 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 perspective view 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 manufacturing the bucket of Figure 1; - Figure 3 is a section along line III-III in Figure 1, during a second step of manufacturing this bucket and - Figure 4 is a plan view of a fabric of reinforcing fibers used in a trough conforms to a second

  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 consists of a first skin 11 forming its lower surface and a second skin 12 forming its upper surface, these skins being made of composite materials with a matrix based on expoxy resin, polyester, vinylester, urethane, polyamide or poly -ether-ether-ketone and carbon-based reinforcing fibers, for example, over most of their surface. These fibers are in the form of a fabric impregnated with resin. The geometry of the skins 11 and 12 is such that they define a volume between them

  in which are stiffening ribs 13.

  We note 14 the middle edge of the bucket 1 which is formed by the skin 11. This edge is subjected to intense friction forces which vary according to the quality of the water used to turn the Pelton turbine. This edge is also subjected to shocks because the water can be charged in

  relatively large debris.

  According to the invention, a protective layer 15

  and for strengthening the edge 14 is provided on the skin 11.

  Layer 15 is formed by an electrolytic deposit

localized on the skin 11.

  So that this deposit leads to an intimate attachment of the layer 15 on the edge 14, and as is more particularly apparent from FIGS. 2 and 3, where the spacing of the fibers is exaggerated compared to reality, the skin 11 includes, at 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 11il in the region of the ridge

  14, while 24 carbon fiber fabrics are superpo-

  sés in the rest of the thickness of the skin 11 and under the fabric 23 at the edge 14. Thus, the fibers 21 are grouped in the vicinity of the external surface S of the skin 11,

in the area of the ridge 14.

  According to a variant not shown of the invention, all of the reinforcing fibers used at the edge 14 could be copper fibers, in which case several

  23 fabric type layers would be superimposed.

  According to another variant, not shown, of the invention, non-woven fiber mats could be used for the

place of fabrics 23 and 24.

  As shown in FIG. 4 for a second embodiment, it is also possible to provide that the metallic fibers 21 extend in a single direction of the fabric 23, for example, that they constitute the warp threads thereof on a part of its width, while the weft threads consist of carbon threads. The carbon weft threads 22 extend both over a portion 23A of the fabric 23 in which they are woven with warp threads 21 of copper and over portions 23B of the fabric 23 in which they are woven with threads of carbon chain 26. Thus, the outer layer of the skin 11 of the bucket 1 is continuous, only part of it being adapted to electrolytic deposition. In this 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 good anchoring of the wires 21 in the structure of the skin 11. In FIG. 4, the fiber spacing is also

  exaggerated to improve understanding of the drawing.

EXAMPLES

  When the skin 11 has been molded, a layer 25 of varnish is deposited on the parts 16 of this skin comprising only carbon fibers 22, namely the strips 24A in the first embodiment or the parts 23B in the second. insulation, before cleaning and degreasing the layers of fabrics 23 comprising fibers 21 and immersing the skin 11 in a bath of metallic compounds with the following distribution: NiCl 50 g / l, NiSo4 150 g / l, H3Po3 8 g / l

H3Po4 26.3 ml / l.

  This bath is maintained at a temperature of around 60 C.

  A nickel counter-electrode and protruding elements are used and a current is applied with a density of approximately 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 abovementioned bath, at which

  case the deposit obtained is of Ni-Co type.

  Of course, other pairs of metals can be envisaged for, on the one hand, the metal fibers 21 and, on the other hand, the electrolyte bath, that is to say the layer

protection or reinforcement 15.

  We can in particular plan to use the following materials: - for metallic fibers: copper, aluminum, 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 can be implemented with a Kaplan turbine blade, with a director, in particular at their respective leading edges, and with a Francis turbine wheel, especially at the leading edges of the blades and at the exposed edges of the belt and the ceiling. In all cases, the areas to be protected are areas with small radii of curvature, which is not a problem.

  given the intimate bonding obtained by electrolytic deposition.

  Other mechanical parts can be made thanks to

  to the invention, such as for example turbine fins.

  Whatever the type of part considered, the

  intimate heat obtained between the protective or reinforcing layer and the substrate makes it possible to envisage supporting elements added to this layer by so-called "plasma" deposition, of the plasma spray type, PVD ("Power Vapor Deposition" or deposition by channel physical), CVD ("Chemical Vapor Deposition"), etc ... Indeed, the localized rise in temperature allowing the deposition is compatible

  with the nature of the layer material, without risk of damage

  magement of the part in composite materials. This additional plasma deposit increases thermal protection, protection against erosion or corrosion,

or even mechanical protection.

Claims (10)

  1. Part, in particular hydraulic component, made of composite material with organic matrix and reinforcing fibers, said part being coated at least locally with a metallic protective layer or based on metal, characterized in that it comprises fibers (21 ) metallic or based on   metal, said layer (15) being formed by electrolytic deposition   as on said metallic or metal-based fibers.   2. Piece according to claim 1, characterized in that said fibers (21) metallic or metal-based are arranged, essentially, in the vicinity of the surface (S) of said piece (1) intended to be coated with said layer (15).   3. Part according to one of the preceding claims,   characterized in that the material of said metallic or metal-based fibers (21) comprises copper, aluminum,   or an alloy of these metals and / or other metallic elements c.   4. Part according to one of the preceding claims,   characterized in that the material of said layer (15) comprises nickel, cobalt, copper or other elements   metallic and / or alloys of these elements.   5. Part according to one of the preceding claims,   characterized in that it is a hydraulic component (1). 6. Method for manufacturing a part, such as a hydraulic component, said part being made of composite material with organic matrix and reinforcing fibers and coated, at least locally, with a protective layer or with metallic reinforcement or with metal base, characterized in that it comprises steps consisting in: - using, in certain areas (14) at least of said part (1), metallic or metal-based fibers (21) and - carrying out a electrolytic deposition of said layer (15) on said metallic or metal-based fibers. 7. Method according to claim 6, characterized in that it consists in isolating the reinforcing fibers (22) from said part (1) located in zones (16) other than that (s) (14) including fibers ( 21) metallic or metal-based, before   to carry out said electrolytic deposition (15).   8. Method according to claim 7, characterized in that it consists in isolating said fibers (22) other than fibers (21) metallic or based on metal by application an insulating varnish (25).   9. Method according to one of claims 6 to 8,   characterized in that it consists in applying, by a "plasma" type deposit, a metallic element on said layer (15)   after the electrolytic deposition 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 metallic compounds including nickel at a temperature of approximately 60 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 deposition is carried out are made of a material including copper.