CMC materials with integrated thermocouple

Abstract

A part includes a substrate made of ceramic matrix composite material, the substrate being coated with a multilayer stack including at least, and in this order, starting from the substrate a tie layer including silicon; an insulation layer including a rare earth disilicate or silica; a barrier layer including a rare earth disilicate; the part further including at least one thermocouple inserted between the insulation layer and the barrier layer.

Claims

1. A part comprising a substrate made of ceramic matrix composite material, said substrate being coated with a multilayer stack comprising, in this order, starting from the substrate: a tie layer comprising silicon; an insulation layer comprising a rare earth disilicate or silica; a barrier layer comprising a rare earth disilicate; the part further comprising at least one thermocouple inserted between the insulation layer and the barrier layer.

2. The part according to claim 1, wherein the insulation layer has a thickness less than or equal to 100 m.

3. The part according to claim 1, wherein the barrier layer has a thickness between 10 m and 2.0 mm.

4. The part according to claim 1, further comprising, on the barrier layer, one or more layers chosen from a thermal barrier, an abradable layer and/or a layer resistant to compounds comprising calcium, magnesium, aluminium and/or silicon and/or oxides of these compounds (CMAS).

5. The part according to claim 1, wherein the part is an aeronautical turbomachine part chosen from: a turbine ring, a blade/vane, a combustion chamber, a high-pressure distributor or a low-pressure distributor.

6. A method for producing the part according to claim 1, the production method comprising: forming the tie layer comprising silicon on at least one surface of the substrate made of ceramic matrix composite material; then forming the insulation layer comprising the rare earth disilicate or silica on the tie layer; then forming the thermocouple on the insulation layer; then forming the barrier layer comprising the rare earth disilicate on the insulation layer, and such that the thermocouple is inserted between the insulation layer and the barrier layer; then a step of heat treatment at a temperature between 1000 C. and 1500 C., for a duration of between 5 hours and 50 hours.

7. The production method according to claim 6, wherein forming the thermocouple comprises a step of depositing a conductive ink by ink jet, aerosol jet printing, screen printing, micro-extrusion or laser deposition.

8. The production method according to claim 7, wherein the conductive ink is a suspension comprising one or more solvents, one or more organic binders and particles, the particles being chosen from nanoparticles or microparticles of silver (Ag), a copper-nickel-manganese alloy (CuNiMn), platinum (Pt) or a platinum-rhodium alloy (PtRh).

9. The production method according to claim 7, wherein forming the thermocouple comprises a step of printing the thermocouple on the insulation layer and a step of high-temperature sintering of the deposited ink in order to remove the organic components of the ink and to sinter together the metallic particles of the ink and to form the continuous circuit of the thermocouple.

10. The production method according to claim 6, wherein the heat treatment step is carried out at a temperature between 1100 C. and 1150 C., for a duration of between 5 hours and 10 hours.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 schematically shows a part at various times during its preparation.

(2) FIG. 2 schematically illustrates a method of the invention.

DESCRIPTION OF THE EMBODIMENTS

(3) The invention is now described by means of the figures which illustrate certain particular embodiments and which must not be interpreted as limiting.

(4) FIG. 1 shows a final part 105 and several intermediate states 101, 102, 103, 104 of the final part 105 during its preparation.

(5) At least one face of the substrate 10 is covered by a tie layer 11 comprising silicon. The purpose of the tie layer 11 is to facilitate the subsequent attachment of the insulation layer 12. For example, the tie layer 11 can be a layer comprising only silicon.

(6) The substrate 10 is made of ceramic matrix composite material chosen from silicon carbide based substrates (SIC).

(7) The tie layer 11 is then covered with an insulation layer 12, on an opposite surface to the substrate. The purpose of the insulation layer 12 is to avoid any contact between the tie layer 11 and the thermocouple 13.

(8) More specifically, and as described above, the contact between the tie layer 11 and the thermocouple 13 is undesirable because silicon from the tie layer 11 can react with metal from the thermocouple 13, which would harm the correct operation of the thermocouple 13.

(9) However, the insulation layer 12 has the lowest possible thickness. For example, the thickness of the insulation layer 12 can be less than or equal to 100 m. More specifically, the smaller the thickness of the insulation layer 12, the more the measurement by the thermocouple 13 is representative of the temperature effectively experienced by the substrate 10.

(10) As described above, the insulation layer 12 comprises either silica or a rare earth disilicate.

(11) In an embodiment the insulation layer 12 consists of silica.

(12) In an alternative embodiment, the insulation layer 12 comprises a rare earth disilicate chosen from ytterbium disilicate and/or yttrium disilicate.

(13) In an embodiment, the insulation layer 12 can have the same composition as the barrier layer 14. In such an embodiment, the continuity between the insulation layer 12 and the barrier layer 14 is excellent, and the production method is further simplified.

(14) As shown in FIG. 1, a thermocouple 13 is then formed on the insulation layer 12. The methods for depositing such a thermocouple 13 will be described below, and in conjunction with the corresponding step from the second figure.

(15) Of course, the thermocouple 13 is formed such that the measurement of the temperature can be accessed from outside the part.

(16) For example, the thermocouple 13 may comprise connection means (not shown in FIG. 1), for example wires, which can connect the thermocouple 13 to outside the part 105. In an embodiment, the wires are formed at the same time as the thermocouple, and can be formed in the same manner.

(17) In an embodiment, in order to obtain such a thermocouple, it is possible to form the thermocouple with wires on the insulation layer 12 and slightly beyond, then to deposit a mask on the end of the wires formed beyond the insulation layer 12 which will be covered by the barrier layer 14, in order to deposit the barrier layer 14 only on the thermocouple 13 but not on the end of the wires, then to remove the cover and thus obtain access to the wires connected to the thermocouple 13.

(18) Of course, the metal or metal alloy composing the thermocouple 13 is chosen so that it can faithfully measure the temperatures of interest in the context of the normal use of the final part 105.

(19) For example, in the case of a turbomachine part, the temperatures measured at the substrate 10, and thus of the thermocouple 13, can be between 1000 C. and 1300 C. It is therefore preferable to choose a thermocouple composed of a copper-nickel-manganese alloy (CuNiMn), platinum (Pt) or a platinum-rhodium alloy (PtRh).

(20) In an embodiment, the insulation layer 12 and the barrier layer 14 are electrically insulating. This embodiment is advantageous because it is not then necessary to pay particular attention to the insulation of the thermocouple 13 or of any wires enabling it to be connected to an instrumentation, because the thermocouple is sandwiched between two insulating layers. This results in a more reliable part because the risk of a contact between the bare wires is reduced.

(21) Once the thermocouple 13 is formed on the insulation layer 12, a barrier layer 14 is deposited on the surface of the insulation layer 12. The thermocouple 13 is inserted between the insulation layer 12 and the barrier layer 14.

(22) As described above, the barrier layer 14 makes it possible to insulate the substrate 10 from the environment to which the part is exposed.

(23) As indicated, the barrier layer 14 comprises a rare earth disilicate. The rare earth disilicate is preferably chosen from ytterbium disilicate and/or yttrium disilicate. More specifically, it is observed that these two rare earths, alone or in combination, make it possible to obtain the best compromise between cost and the desired performance for the barrier layer 14.

(24) The barrier layer 14 can, for example, have a thermally insulating or environmentally insulating function, in other words providing a seal against conventionally encountered environmental pollutants such as compounds comprising calcium, magnesium, aluminium or silicon, in particular oxides of these compounds (conventionally called CMAS).

(25) In an embodiment, the barrier layer 14 can be covered with an additional barrier, not shown in FIG. 1, able to fulfil an additional function to that already fulfilled by the barrier layer 14.

(26) In an embodiment, the thermocouple is in direct contact with the insulation layer 12, and in direct contact with the barrier layer 14.

(27) The thickness of the barrier layer 14 is chosen to represent a compromise between the weight, cost and desired specifications for the final part 105.

(28) As described in FIG. 1, in the final part 105, the thermocouple 13 is located inserted between the insulation layer and the barrier layer. The thermocouple 13 inserted between the insulation layer and the barrier layer makes it possible to obtain a reliable measurement of the temperature effectively experienced in the final part 105 between the substrate 10 and the barrier layer 14.

(29) In an embodiment, the part comprises no layers other than the substrate 10, the tie layer 11, the insulation layer 12 and the barrier layer 14. Of course, the part comprises a thermocouple 13 inserted between the insulation layer 12 and the barrier layer 14.

(30) FIG. 2 schematically shows the various steps E1 to E7 of a method for preparing a final part 105, as described above, starting from a substrate 10 constituting an initial part 101. The steps represented by the dashed boxes of FIG. 2 are optional.

(31) The preparation method shown comprises a first step E1 of preparing a tie layer 11 at the surface of a substrate 10.

(32) For example, the tie layer 11 can be formed in a manner that is known per se, for example by thermal spraying, PVD or CVD on at least one surface of a substrate 10.

(33) This first step E1 makes it possible to obtain an intermediate part 102, wherein the substrate 10 is covered on at least one surface by the tie layer 11.

(34) The method then comprises a step E2 of forming an insulation layer 12. This step E2 makes it possible to obtain the intermediate part 103, wherein an insulation layer 12 has been formed at the surface of the tie layer 11.

(35) In the embodiments where the insulation layer comprises a rare earth disilicate, step E2 of forming the insulation layer 12 can be carried out by thermal spraying, physical vapour deposition or chemical vapour deposition, or by liquid deposition then sintering of one or more powders.

(36) The method can optionally further comprise a step E3 of polishing the insulation layer 12.

(37) Such a polishing step can be carried out by mechanical polishing or chemical polishing.

(38) This step makes it possible to achieve a better attachment of the thermocouple 13 and reduces the risk of electrical discontinuity in the thermocouple 13.

(39) The method then comprises a step E4 of forming a thermocouple 13 on the insulation layer 12, in order to form the intermediate part 104.

(40) For example, the thermocouple 13 can be formed directly on the insulation layer 12 by means of a conductive ink.

(41) For example, the conductive ink can comprise a plurality of metallic particles dissolved in a solvent, as previously described.

(42) For example, the formation can comprise depositing a conductive ink by ink jet, aerosol jet printing, screen printing or micro-extrusion.

(43) Alternatively, the thermocouple can be deposited by air plasma spraying (APS), high velocity oxy-fuel (HVOF), solution plasma spraying, cold spraying, electron beam physical vapour deposition (EBPVD), chemical vapour deposition (CVD), pulsed laser, plasma or screen printing.

(44) As described above, step E4 of forming the thermocouple 13 can comprise the depositing of an ink, immediately followed by its sintering in order to form the thermocouple.

(45) Alternatively, step E4 of forming the thermocouple can comprise depositing of an ink, optionally followed by its drying.

(46) If step E4 of forming the thermocouple comprises a printing step which is not followed by a sintering step, then the heat treatment step E7 can enable the sintering of the particles comprised in the ink in order to form the final thermocouple.

(47) The method then comprises a step E6 of depositing a barrier layer 14 comprising a rare earth disilicate on the insulation layer 12 and such that the thermocouple 13 is inserted between the insulation layer 12 and the barrier layer 14.

(48) The method presented in FIG. 2 then comprises a heat treatment step E7. This heat treatment step E7 can stabilise the barrier layer 14, and optionally the insulation layer 12. Such a step E7 also makes it possible, in certain embodiments, to finalise the sintering of the thermocouple 13.

(49) The expression between . . . and . . . should be understood as including the limits.