GAS TURBINE PART AND METHOD FOR MANUFACTURING SUCH GAS TURBINE PART

Abstract

The present disclosure relates to a gas turbine part, which can be exposed to high temperatures and centrifugal forces within a gas turbine. The gas turbine part can include plural sliced parts, wherein at least one of said sliced parts is made from a ternary ceramic called MAX phase, having the formula M.sub.n+1AX.sub.n, where n=1, 2, or 3, M is an early transition metal such as Ti, V, Cr, Zr, Nb, Mo, Hf, Sc, Ta, and A is an A-group element such as Al, Si, P, S, Ga, Ge, As, Cd, In, Sn, Tl, Pb, and X is C and/or N.

Claims

1. Gas turbine part configured for exposure to heat and centrifugal forces within a gas turbine, wherein said gas turbine part comprises: a plurality of sliced parts, wherein at least one of said sliced parts is made from a ternary ceramic called MAX phase, having a formula M.sub.n+1AX.sub.n, where n=1, 2, or 3, M is an early transition metal selected from a group which includes Ti, V, Cr, Zr, Nb, Mo, Hf, Sc, Ta, and A is an A-group element selected from a group which includes Al, Si, P, S, Ga, Ge, As, Cd, In, Sn, Tl, Pb, and X is C and/or N, whereby M is in a range of 40-60 at-%, A is in a range of 10-30 at-% and X is in a range of 20-40 at-%, and whereby M+A+X is in a range of 80-100% with 0-20% being elements other than those already listed and are a result of impurities or oxidation, and wherein said sliced parts are joined.

2. Gas turbine part as claimed in claim 1, wherein said sliced parts, are joined by a bolt, a brazed joint, an interlock or a combination of these joints to fix said sliced parts.

3. Gas turbine part as claimed in claim 1, wherein said MAX phase is single phase Ti.sub.2AlC or a composition of two phases, Ti.sub.2AlC and Ti.sub.3AlC.sub.2, where a range of the Ti.sub.2AlC phase is 60-95%.

4. Gas turbine part as claimed in claim 1, wherein said MAX phase is single phase Ti.sub.3SiC.sub.2 or a composition of two phases, Ti.sub.3SiC.sub.2 and Ti.sub.4SiC.sub.3, where a range of the Ti.sub.3SiC.sub.2 phase is 60-95%.

5. Gas turbine part as claimed in claim 1, wherein said MAX phase is a mixture of two main phases Ti.sub.3SiC.sub.2 and Ti.sub.2AlC, where a range of the Ti.sub.3SiC.sub.2 phase is 40-90%, and whereby two MAX phases are in a range of 50-100% with 0-20% being other MAX phases or elements.

6. Gas turbine part as claimed in claim 1, wherein said gas turbine part possesses anisotropic material properties by combining several sliced parts with different crystalline orientation.

7. Gas turbine part as claimed in claim 6, wherein in one of the sliced parts a crystalline orientation is in a direction of intended centrifugal force, and in another one of the sliced parts a crystalline orientation is perpendicular to the direction of centrifugal force.

8. Gas turbine part as claimed in claim 1, wherein said gas turbine part possesses anisotropic material properties by combining several sliced parts with fibers in different orientations.

9. Gas turbine part as claimed in claim 1, wherein said gas turbine part is a rotor heat shield.

10. Method for manufacturing a gas turbine part, the method comprising: a) providing a ternary ceramic called MAX phase, having a formula M.sub.n+1AX.sub.n, where n=1, 2, or 3, M is an early transition metal selected from a group which includes Ti, V, Cr, Zr, Nb, Mo, Hf, Sc, Ta, and A is an A-group element selected from a group which includes Al, Si, P, S, Ga, Ge, As, Cd, In, Sn, Tl, Pb, and X is C and/or N, whereby M is in a range of 40-60 at-%, A is in a range of 10-30 at-% and X is in a range of 20-40 at-%, and whereby M+A+X is in a range of 80-100% with 0-20% being elements other than those already listed and are a result of impurities or oxidation; b) manufacturing a plurality of sliced parts, whereby at least one of said sliced parts is made from said MAX phase; and c) joining said sliced parts to build said gas turbine part.

11. Method as claimed in claim 10, wherein said joining step c) comprises: bolting, brazing and interlocking or combination of these to fix said sliced parts.

12. Method as claimed in claim 10, wherein sliced parts with different crystalline orientation are combined to produce a gas turbine part with anisotropic material properties.

13. Method as claimed in claim 10, wherein fibers are used to produce a gas turbine part with anisotropic material properties.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention is now to be explained more closely by means of different embodiments and with reference to the attached drawings.

[0032] FIG. 1-3 show the subdivision of an exemplary rotor heat shield design of a gas turbine into three separate slices to be manufactured separately according to an embodiment of the invention;

[0033] FIG. 4 shows a first example of how the slices are joined after being manufactured separately;

[0034] FIG. 5 shows a second example of how the slices are joined after being manufactured separately;

[0035] FIG. 6 shows slices similar to FIG. 2, with different crystalline orientation in order to achieve an anisotropic material; and

[0036] FIG. 7 shows a rotor heat shield with separate parts (fins) on the top of the heat shield, which are made of Max phases, and are inserted into a recess on top of the heat shield.

DETAILED DESCRIPTION OF DIFFERENT EMBODIMENTS OF THE INVENTION

[0037] The invention is about producing a gas turbine part, especially rotor heat shield of gas turbine using new materials, design and processing, where new materials provide low density and therefore reduce centrifugal force on rotor, and new design and processing methods facilitate fabrication of the parts.

[0038] This allows building very large gas turbines without changing rotor materials. This can be done by application of new materials and processing to manufacture components with reduced specific density and robust mechanical strength.

[0039] In this connection, so-called MAX phases, ternary ceramics, are extremely interesting candidates that can fulfill this request, with density of about 4-4.5 g/cm.sup.3, thermal expansion coefficient>810.sup.6 K.sup.1, thermal conductivity>50 W/mK at 700 C., fracture toughness>5 MPa.Math.m.sup.1/2, and high oxidation resistance.

[0040] The proposed solution of using MAX phases will solve the oxidation problem, especially on fins 14 of a rotor heat shield 13, as shown in FIG. 7.

[0041] The MAX phases, which are used to produce hot turbine parts by powder metallurgy processes, are a family of ceramics having M.sub.n+1AX.sub.n formula, where n=1, 2, or 3, M is an early transition metal such as Ti, V, Cr, Zr, Nb, Mo, Hf, Sc, Ta and A is an A-group element such as Al, Si, P, S, Ga, Ge, As, Cd, In, Sn, Tl, Pb and X is C and/or N. M is in the range of 40-60 at-%, A in the range of 10-30 at-% and X in the range of 20-40 at-%. And M+A+X is in the range of 80-100% and 0-20% elements, which are not listed above and are result of impurities or oxidation.

[0042] One preferred composition of MAX phase is single phase Ti.sub.2AlC, or two phases, Ti.sub.2AlC and Ti.sub.3AlC.sub.2 (211 and 312), where the range of the 211 phase is 60-95%.

[0043] Another preferred composition of MAX phase is single phase Ti.sub.3SiC, or two phases, Ti.sub.3SiC.sub.2 and Ti.sub.4SiC.sub.3 (312 and 413), where the range of the 312 phase is 60-95%.

[0044] Another preferred composition of MAX phase is a mixture of two main phases Ti.sub.3SiC.sub.2 and Ti.sub.2AlC, where the range of the Ti.sub.3SiC.sub.2 phase is 40-90%, and whereby two MAX phases are in the range of 50-100% with 0-20% being other MAX phases or elements.

[0045] Especially, a rotor heat shield of gas turbine (the part) is produced from MAX phase by powder technology processes. A rotor heat shield is for example shown in FIG. 2 of document EP 1 079 070 A2.

[0046] FIG. 1 of the present application shows the design of a rotor heat shield 10, which is mounted on the rotor of a gas turbine to shield the rotor against the hot gas temperatures of the hot gas path. The T-shaped rotor heat shield 10 has a bottom part 11, which is in contact with the not shown root section of the rotor. A top part 13 with a plurality of parallel fins 14 on its upper side is in contact with the tips of the stationary vanes at the stator part of the turbine (not shown). Top part 13 and bottom part 11 are connected by an intermediate part 12. As the rotor heat shield 10 rotates with the rotor, it is subjected to a centrifugal force CF, the direction of which is marked by an arrow in FIG. 1 and FIG. 3.

[0047] The rotor heat shield 10 is (in the example shown in FIG. 1-3) subdivided into three separate sliced parts 10a, 10b and 10c along the direction of centrifugal force CF. Other subdivisions are possible. Of the three sliced parts 10a, 10b and 10c one, two or all parts are made from a MAX phase having M.sub.n+1AX.sub.n formula, where n=1, 2, or 3, M is an early transition metal such as Ti, V, Cr, Zr, Nb, Mo, Hf, Sc, Ta and A is an A-group element such as Al, Si, P, S, Ga, Ge, As, Cd, In, Sn, Tl, Pb and X is C and/or N. M is in the range of 40-60 at-%, A in the range of 10-30 at-% and X in the range of 20-40 at-%. And M+A+X is in the range of 80-100% and 0-20% elements, which are not listed above and are result of impurities or oxidation.

[0048] According to FIGS. 4 and 5 the sliced parts 10a, 10b and 10c are then joined by bolting, brazing, interlocking with a bolt 15 and respective interlocks 16 (FIG. 4) or 17 (FIG. 5), or combination of these is used to fix the parts.

[0049] As current rotor heat shields are usually bending due to thermo-mechanical load and heating and cooling of different mass distributions, it is further proposed to provide a rotor heat shield with anisotropic material produced from several sliced parts 10a, 10b and 10c (see FIG. 6), where in one sliced part a crystalline orientation is in the direction of centrifugal force, and in another sliced part a crystalline structure is perpendicular to the direction of centrifugal force. In FIG. 6, this different crystalline orientation is illustrated by a different hatching.

[0050] This is especially beneficial for a T-shaped rotor heat shield (including the top part 13 in contact with vane tip/shroud and the bottom part 11 in contact with the root section) where the top part 13 is not bending due to the combination of different orientations and the high thermal conductivity of the MAX phase.

[0051] Alternative to different crystalline orientation the anisotropic material properties are may be produced with immersed fibers of different orientation.

[0052] In addition, according to another embodiment, as shown in FIG. 7, separate parts (fins 14) on the top of the heat shield may be made of MAX phases, which fins 14 could be inserted into respective recesses on top of the heat shield 13.

LIST OF REFERENCE NUMERALS

[0053] 10 rotor heat shield (T-shape) [0054] 10a-c sliced part [0055] 11 bottom part (in contact with root section) [0056] 12 intermediate part [0057] 13 top part (in contact with vane tip) [0058] 14, 14 fin [0059] 15 bolt [0060] 10 16, 17 interlock [0061] CF centrifugal force