Turbine engine stator wall covered in an abradable coating

Abstract

An annular turbine engine stator portion including a structural support provided in succession with a bonding underlayer and with an abradable coating formed by a resin filled with microbeads, the bonding underlayer for fastening the abradable coating to the structural support being formed by fiber reinforcement made of long fibers having a peripheral portion of the reinforcement that is secured to the structural support and having a central portion thereof that is impregnated with the resin filled with microbeads while the abradable coating is being fastened to the structural support.

Claims

1. An annular turbine engine stator portion comprising: a structural support provided in succession with a bonding underlayer and with an abradable coating formed by a resin filled with microbeads, the bonding underlayer having a peripheral portion and a central portion and fastening the abradable coating to the structural support, the bonding underlayer formed of fiber reinforcement made of fibers, only the peripheral portion of the bonding underlayer secured to the structural support by adhesive bonding or by co-curing, the central portion of the bonding underlayer impregnated during deposition of said abradable coating.

2. An annular turbine engine stator portion according to claim 1, wherein the fiber reinforcement comprises one or more juxtaposed plies of fiber fabric.

3. An annular turbine engine stator portion according to claim 2, wherein the fiber reinforcement comprises a non-impregnated fabric ply of glass fibers or of any other fiber reinforcement.

4. An annular turbine engine stator portion according to claim 2, wherein the fiber reinforcement comprises a plurality of plies that are pre-impregnated at least in part at their periphery with fabric of glass fibers or of any other fiber reinforcement.

5. An annular turbine engine stator portion according to claim 1, wherein the structural support is based on a metal alloy, and the peripheral portion is adhesively bonded to the structural support by an epoxy resin.

6. An annular turbine engine stator portion according to claim 1, wherein the structural support is based on composite material, and the peripheral portion is co-cured with the structural support while preparing the structural support.

7. An annular turbine engine stator portion according to claim 1, wherein the resin filled with microbeads is a silicone resin or an epoxy resin.

8. An annular turbine engine stator portion according to claim 7, wherein the microbeads are hollow beads of glass or of a refractory material.

9. An annular turbine engine stator portion according to claim 1, wherein the abradable coating is fastened to the structural support by deposition by thermal spraying, by injection, by molding, or by spreading, to impregnate the fiber reinforcement and the structural support.

10. A turbine engine stator comprising a plurality of annular portions according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Other characteristics and advantages of the present invention appear from the following description made with reference to the accompanying drawing which shows an embodiment having no limiting character, and in which:

(2) FIG. 1 is a section view of an annular turbine engine stator portion of the invention made of metal; and

(3) FIG. 2 is a section view of an annular turbine engine stator portion made of composite material.

DETAILED DESCRIPTION OF EMBODIMENTS

(4) FIG. 1 is a section view of a portion of a retention casing of an axial turbine engine fan, e.g. formed by connecting a plurality of sectors together end-to-end in the circumferential direction. The casing surrounds a rotary assembly made up of a plurality of blades (not shown), with the clearance between the inside surface of the casing and the tips of the blades being zero or almost zero.

(5) This annular stator portion comprises a structural support 10 provided on the inside (facing the flow of combustion gas) and in succession: a bonding layer 12; and a thermal protection coating 14 made of an abradable material having pores and into which the tips of the blades can penetrate in part without suffering severe wear.

(6) In this first embodiment, the structural support 10 is made of metal alloy, e.g. a titanium or an aluminum alloy.

(7) The thermal protection coating 14 is made of a material having pores, and of satisfactory strength at the temperatures usually encountered in operation. Conventionally, in order to constitute this abradable coating, recourse is had to materials based on silicone or epoxy resin filled with a pore-generating agent of the hollow microbead type made of refractory material, and in particular of glass.

(8) In the invention, the bonding underlayer 12 serving to bond the abradable coating with the surface of the structural support is formed by reinforcement of glass fibers or any other long-fiber reinforcement (e.g. using carbon or aramid fibers) that is secured in part at its periphery to the structural support 10.

(9) The fiber reinforcement is constituted by one or more juxtaposed plies of two-dimensional long-fiber fabric. When the reinforcement has only one ply, it is preferably not impregnated (dry) and it is advantageously adhesively bonded to the structural support 10 at its periphery (or at least along two of its lateral edges 12A and 12B) using an epoxy resin (or indeed a silicone resin when the abradable coating is based on silicone). In contrast, when the composite reinforcement comprises a plurality of plies, they are independent of one another and they may then be previously pre-impregnated at least in part at their periphery, in particular along their lateral edges, and they are then held by being adhesively bonded along these lateral edges to the structural support 10, e.g. using epoxy resin. This impregnation may advantageously be performed manually (laminating by hand), e.g. using a roller or a spray gun.

(10) In these two configurations, the central portion of the reinforcement 12C is left free (i.e. not adhesively bonded to the structural support) and it is impregnated during the physical deposition of the abradable coating, e.g. by thermally spraying powder, while using known plasma deposition techniques when the fabric is made of metal long fibers. In other circumstances, the abradable material may merely be injected, molded, or spread in such a manner as to impregnate the fiber reinforcement and the surface of the structural support.

(11) FIG. 2 shows another embodiment of the invention that is more particularly adapted to a structural support 10 that is made of composite material being constituted in conventional manner by fiber reinforcement made of carbon, glass, aramid, or ceramic fibers embedded in an epoxy resin or in a resin having similar properties. Under such circumstances, the bonding underlayer 12 is not bonded at its periphery directly on the structural support 10 with the help of an epoxy resin, but each lateral edge 12D, 12E is preferably co-cured together with the structural support while the structural support is being prepared in such a manner that the reinforcement is directly incorporated with the structural support's own reinforcement of fibers 10A structuring its surface. Naturally, care is taken to ensure that this curing does not affect the central portion that is to remain free. The structure of the bonding underlayer 12 is nevertheless identical to the structure described above and is formed by reinforcement of glass fibers or of any other long reinforcing fibers comprising a dry ply or a plurality of pre-impregnated plies of two-dimensional long-fiber fabric that are nevertheless co-cured with and not adhesively bonded to the structural support.