COATING COMPOSITION COMPRISING CHROMIUM AND ALUMINUM AND COATINGS FORMED USING THE SAME

Abstract
This disclosure generally relates to coating compositions comprising chromium and aluminum and coatings formed using the same, and more particularly to bond coat compositions and coatings for use in various gas turbine applications. In one aspect, a material composition comprises M, Cr, and Al, wherein M is one or more of Ni, Co, and Fe. The material composition is configured to form a BCC ordered phase and a disordered metallic phase of either a BCC or FCC crystal structure.
Description
BACKGROUND
Field

This disclosure generally relates to coating compositions comprising chromium and aluminum and coatings formed using the same, and more particularly to bond coat compositions and coatings for use in various gas turbine applications.


SUMMARY

Disclosed herein are embodiments of a thermal spray feedstock material, comprising, in weight percent (wt. %) nickel: 18-31; cobalt: 18-31; iron: 18-31; chromium: 16-27; and aluminum: 2-13. In other embodiments, the thermal spray feedstock material comprises, in weight percent: Ni: about 12.15-about 23.73, Co: about 23.34-about 48.78, Fe: about 11.56-about 22.58, Cr: about 5.03-about 21.03, and Al: about 8.84-about 16.75. In some embodiments, the feedstock material further comprises 0.25-1 wt. % yttrium.


In some embodiments, the feedstock material is configured to have, under equilibrium thermodynamic conditions, a first and second matrix proximity of 85% or higher. In some embodiments, the feedstock material, is configured to have under equilibrium thermodynamic conditions, a first and second matrix proximity of 90% or higher. In some embodiments, the feedstock material is configured to have, under equilibrium thermodynamic conditions, a first and second matrix proximity of 95% or higher.


In some embodiments, the feedstock material is configured to have, under equilibrium thermodynamic conditions, a B2 formation delta in a range of 0 K to 150 K. In some embodiments, the feedstock material is configured to have, under equilibrium thermodynamic conditions, a B2 formation delta in a range of 25 K to 80 K. In some embodiments, the feedstock material is configured, under thermodynamic equilibrium conditions, to comprise 40% or more of a B2 ordered phase. In some embodiments, the feedstock material is configured, under thermodynamic equilibrium conditions, to comprise 45% or more of a B2 ordered phase. In some embodiments, the feedstock material is configured, under thermodynamic equilibrium conditions, to comprise 50% or more of a B2 ordered phase. In some embodiments, the feedstock material is configured, under thermodynamic equilibrium conditions, to comprise a B2 ordered phase at any percentage in a range defined by any of the above percentages.


In some embodiments, the feedstock material is configured, under thermodynamic equilibrium conditions, to comprise 5 mole % or greater of oxidation resistant phases. In some embodiments, the feedstock material is configured, under thermodynamic equilibrium conditions, to comprise 10 mole % or greater of oxidation resistant phases. In some embodiments, the feedstock material is configured, under thermodynamic equilibrium conditions, to comprise 20 mole % or greater of oxidation resistant phases. In some embodiments, the feedstock material is configured, under thermodynamic equilibrium conditions, to comprise oxidation resistant phases at a mole % in a range defined by any of the above percentages. In some embodiments, the oxidation resistant phases comprise carbides such as chromium carbides.


Also disclosed herein are embodiments of a coating formed from the feedstock material disclosed herein. The coating can be a thermal spray coating and/or a bond coating. It will be understood that, in various embodiments described herein, any of material characteristics of one of a feedstock material and a coating, including the compositions and/or thermodynamic properties, can also be present in the other of the feedstock and the coating. described herein.


In some embodiments, the coating comprises fine scale phases of at least 85 mole % or greater. In some embodiments, the coating comprises fine scale phases of at least 90 mole % or greater. In some embodiments, the coating comprises fine scale phases of at least 95 mole % or greater. In some embodiments, the coating comprises fine scale phases at a mole % in a range defined by any of the above percentages.


In some embodiments, the coating comprises at least 40 mole % of a B2 ordered phase. In some embodiments, the coating comprises at least 45 mole % of a B2 ordered phase. In some embodiments, the coating comprises at least 50 mole % of a B2 ordered phase. In some embodiments, the coating comprises a B2 ordered phase at a mole % in a range defined by any of the above percentages.


In some embodiments, the coating comprise 5 volume % or greater of oxidation resistant phases. In some embodiments, the coating comprise 15 volume % or greater of oxidation resistant phases. In some embodiments, the coating comprise 20 volume % or greater of oxidation resistant phases. In some embodiments, the oxidation resistant phases comprise chromium carbides. In some embodiments, the coating comprises oxidation resistant phases at a volume % in a range defined by any of the above percentages.


In some embodiments, the coating can exhibit greater than 270 cycles before failure during an FCT testing at 1150° C. In some embodiments, the coating can exhibit greater than 300 cycles before failure during an FCT testing at 1150° C. In some embodiments, the coating can exhibit greater than 330 cycles before failure during an FCT testing at 1150° C.


In some embodiments, the coating is applied on a Ni-based superalloy. In some embodiments, the coating can comprise a thermal barrier coating applied onto the coating. In some embodiments, a thermal spray coating comprises, in weight percent (wt. %): nickel: 18-31; cobalt: 18-31; iron: 18-31; chromium: 16-27; and aluminum: 2-13.


Also disclosed herein are embodiments of a method of forming a heat resistant coating comprising applying a bond coat layer unto a Ni-based superalloy, the bond coat layer comprising Ni: about 12.15-about 23.73, Co: about 23.34-about 48.78, Fe: about 11.56-about 22.58, Cr: about 5.03-about 21.03, and Al: about 8.84-about 16.75, and applying a thermal barrier coating onto the bond coat layer. In some embodiments, the method of forming comprises thermal spraying. In some embodiments, the bond coat layer further comprises 0.25-1 wt. % yttrium.


Disclosed herein are embodiments of a bond coat material comprising M, Cr, and Al, wherein M is one or more of Ni, Co, and Fe which under equilibrium thermodynamics will precipitate a BCC ordered phase from the liquid upon cooling followed by a disordered metallic of either BCC or FCC crystal structure, wherein the microstructure comprises a fine scale structure making up 85% or greater of the total microstructure as characterized by phases which are 100 nm in size or smaller when solidified from a liquid state at a rate of 20 degrees K/second or slower.


In some embodiments, the formation temperature of the BCC ordered phase and the disordered phase is 0-150 K. In some embodiments, the BCC ordered phase and the disordered metallic phase are compositionally similar as defined by a cosine similarity of greater than 85% when comparing the chemistries of both phases. In some embodiments, the BCC ordered phase comprises greater than 40% of the total microstructure. In some embodiments, the material thermodynamically forms an oxidation resistant phase at a mole fraction of 10% or greater. In some embodiments, the material forms an oxidation resistant phase which is chromium carbide at a mole fraction of 10% or greater. In some embodiments, the microstructure comprises a fine scale structure making up 85% or greater of the total microstructure as characterized by phases which are 100 nm in size or smaller when solidified from a liquid state at a rate of 20 degrees K/second or slower.


In some embodiments, the composition comprises in wt. %, Ni: 12.15-23.73 (or about 12.15-about 23.73), Co: 23.34-48.78 (or about 23.34-about 48.78), Fe: 11.56-22.58 (or about 11.56-about 22.58), Cr: 5.03-21.03 (or about 5.03-about 21.03), and Al: 8.84-16.75 (or about 8.84-about 16.75). In other embodiments, the composition comprises in wt %, nickel: 18-31; cobalt: 18-31; iron: 18-31; chromium: 16-27; and aluminum: 2-13.


In some embodiments, the composition comprises in wt. %, Ni: 20-22 (or about 20-about 22), Co: 21-23 (or about 21-about 23), Fe: 20-24.2 (or about 20-about 24.2), Cr: 26-30 (or about 26-about 30), C: 0.5-1 (or about 0.5-about 1), and Al: 6-8 (or about 6-about 8).


In some embodiments, the composition comprises yttrium from 0.1-1 wt. %.


Also disclosed herein are embodiments of a bond coat material comprising M, Cr, and Al, wherein M is one or more of Ni, Co, and Fe which under equilibrium thermodynamics will precipitate a BCC ordered phase from the liquid upon cooling followed by a disordered metallic of either BCC or FCC crystal structure.


Further disclosed herein are embodiments of a thermal spray feedstock material configured for high temperature use, the feedstock material comprising, in wt. %, Ni: about 18-about 31, Co: about 18-about 31, Fe: about 18-about 31, Cr: about 16-about 27, and Al: about 2-about 13.


Further disclosed herein are embodiments of a thermal spray feedstock material configured for high temperature use, the feedstock material comprising, in wt. %, Ni: about 21-about 28, Co: about 21-about 28, Fe: about 21-about 28, Cr: about 18-about 15, and Al: about 6-about 10.





BRIEF DESCRIPTION OF THE DRAWINGS


FIG. 1 illustrates a cosine similarity equation.



FIG. 2 illustrates an embodiment of a phase diagram for P118-X5.



FIG. 3 illustrates an embodiment of a phase diagram for Diamalloy® 4700.



FIG. 4 illustrates an SEM micrograph of P118-X5 at 2kX magnification.



FIG. 5 illustrates an SEM micrograph of Diamalloy® 4700 at 1kX magnification.



FIG. 6 illustrates an embodiment of a phase diagram for P118-X11.



FIG. 7 illustrates an SEM micrograph of P118-X11 at 12kX magnification.



FIG. 8 illustrates an SEM micrograph of P118-X11 at 1kX magnification.





DETAILED DESCRIPTION

MCrAlY alloys, which refer to some alloys comprising nickel, cobalt, iron, chromium and optionally yttrium, can be used to protect Ni-based superalloys from high temperature oxidation and corrosion, though the particular substrate type is not limiting, and are particularly useful in various gas turbine applications. For high temperature applications, such as at temperature of 900° C. or higher, a thermal barrier coating (TBC) can be applied to the top of the bond coat to reduce the effective surface temperature of Ni-based superalloys. Embodiments of the disclosure can be an intermediate coating between the superalloy and the TBC.


The TBC is applied on top of a superalloy to reduce the temperature at the substrate interface. However, the TBC tends to be quite porous so oxygen can still penetrate and attack the substrate. Advantageously, embodiments of the disclosed MCrAlY bond coat can be applied between the layers, and at elevated temperatures the bond coat can form an oxide layer on the surface. This oxide layer is a thermally grown oxide (TGO). This TGO layer can be very dense and may not react with oxygen. Accordingly, the TGO layer formed from a MCrAlY bond coat can prevent or reduce the amount of oxygen that reaches the substrate. At high temperatures though, the MCrAlY starts to form a thermally grown oxide (TGO) between itself and the TBC.


Although the TGO is useful for preventing further oxygen penetration, it can grow too thick, which may result in high internal stresses during thermal cycling which may ultimately cause spalling of the TBC and failure of the system. This disclosure describes embodiments of a new family of MCrAlYs that have shown increased cycle life as determined by furnace cycle testing.


As disclosed herein, the term alloy can refer to the chemical composition forming the powder, the powder itself, and the composition of the metal component formed by the heating and/or deposition of the powder.


In some embodiments, the material may be applied to a substrate, such as through thermal spray processing. In some embodiments, high velocity oxygen fuel spraying, atmospheric plasma spraying, or controlled atmospheric plasma spraying can be performed to apply the material to a substrate. In some embodiments, the material may be applied via welding or other methods, and the application procedure is not limiting.


Composition:


In some embodiments, various material compositions disclosed herein, including those of a thermal spray feedstock material, a thermal spray coating and a bond coat material, can include, in weight percent:

    • nickel (Ni): 12.15-23.73 (or about 12.15-about 23.73)
    • cobalt (Co): 23.34-48.78 (or about 23.34-about 48.78)
    • iron (Fe): 11.56-22.58 (or about 11.56-about 22.58)
    • chromium (Cr): 5.03-21.03 (or about 5.03-about 21.03)
    • aluminum (Al): 8.84-16.75 (or about 8.84-about 16.75)


In some embodiments, various material compositions disclosed herein, including those of a thermal spray feedstock material, a thermal spray coating and a bond coat material, can include:

    • Ni: 23.24-24.18 (or about 23.24-about 24.18)
    • Co: 36.75-38.84 (or about 36.75-about 38.84)
    • Cr: 21.42-29.34 (or about 21.42-about 29.34)
    • Al: 10.68-15.56 (or about 10.68-about 15.56)


In some embodiments, various material compositions disclosed herein, including those of a thermal spray feedstock material, a thermal spray coating and a bond coat material, can include:

    • Ni: 20-22 (or about 20-about 22)
    • Co: 21-23 (or about 21-about 23)
    • Fe: 20-24.2 (or about 20-about 24.2)
    • Cr: 26-30 (or about 26-about 30)
    • C: 0.5-1 (or about 0.5-about 1)
    • Al: 6-8 (or about 6-about 8)


In some embodiments, various material compositions disclosed herein, including those of a thermal spray feedstock material, a thermal spray coating and a bond coat material, can include:

    • Ni: 18-31 (or about 18-about 31)
    • Co: 18-31 (or about 18-about 31)
    • Fe: 18-31 (or about 18-about 31)
    • Cr: 16-27 (or about 16-about 27)
    • Al: 2-13 (or about 2-about 13)


In some embodiments, various material compositions disclosed herein, including those of a thermal spray feedstock material, a thermal spray coating and a bond coat material, can include:

    • Ni: 21-28 (or about 21-about 28)
    • Co: 21-28 (or about 21-about 28)
    • Fe: 21-28 (or about 21-about 28)
    • Cr: 18-25 (or about 18-about 25)
    • Al: 6-10 (or about 6-about 10)


In some embodiments, various material compositions disclosed herein, including those of a thermal spray feedstock material, a thermal spray coating and a bond coat material, can include:

    • M: Balance whereas M is a combination of nickel, cobalt, and iron
    • Cr: 10-50 (or about 10-about 50)
    • C: 0.5-3.5 (or about 0.5-about 3.5)
    • Al: 5-14 (or about 0.5-about 3.5)


In some embodiments, any or all of the above ranges can be defined by the following relationship:

    • 6%<Al+0.25*Cr<16%
    • about 6%<Al+0.25*Cr<about 16%


Embodiments of the disclosure can form an alloy which forms chromium carbide precipitates in a gamma matrix.


In some embodiments, any or all of the above ranges can be defined by the following relationship:

    • 15%<Al+0.25*Cr<21%
    • about 15%<Al+0.25*Cr<about 21%


In some embodiments, alloys can have a lower Al content which can therefore form a gamma matrix. A gamma matrix is generally a continuous matrix with a face-centered cubic (FCC) nickel based austenitic phase that usually contains a high percentage of solid solution elements. With higher Al content, the alloy may form a gamma and beta matrix. A beta matrix generally has a body centered cubic structure and is often but not always found at high temperature. Advantageously, carbides can be added into the microstructure to help improve thermal and resistance properties.


In some embodiments, the MCrAlY material can form an alloy of chromium carbide precipitates in a matrix comprising a combination of gamma and beta whereas the gamma/beta ratio is 0.5 to 2.


In some embodiments, anywhere from 0.1-1 (or about 0.1-about 1) weight percent of yttrium can be added to any of the above compositions described. The yttrium can help the TGO layer adhere to the MCrAlY, and can reduce the chance of spallation.


Table 1 illustrates certain compositions encompassed by this disclosure.









TABLE 1







Arc Melted Sample Compositions















Ni
Co
Fe
Cr
Mn
C
Al


















P118-X1
5
9.99
40.01
5
8

32


P118-X2
20
20
15.01
5
10

30


P118-X3
30
30.01
9.99
5
10

15


P118-X4
25.33
25.44
24.11
22.44


2.68


P118-X5
23.73
23.83
22.58
21.03


8.84


P118-X6
23.25
23.34
22.12
20.6


10.69


P118-X7
23.24
36.75

29.34


10.68


P118-X8
24.18
38.84

21.42


15.56


P118-X9
22.71
45.61
16.21
5.03


10.44


P118-X10
12.15
48.78
11.56
10.76


16.75


P118-X11
22
21
20.5
28

0.5
8


P118-X12
20
21
20.2
30

0.8
8


P118-X13
20
21
20
30

1
8


P118-X14
22
23
22.5
26

0.5
6


P118-X15
20
21
24.2
28

0.8
6


P118-X16
20
21
22
30

1
6









The disclosed alloys can incorporate the above elemental constituents to a total of 100 wt. %. In some embodiments, the alloy may include, may be limited to, or may consist essentially of the above named elements. In some embodiments, the alloy may include 2 wt. % (or about 2 wt. %) or less, 1 wt. % (or about 1 wt. %) or less, 0.5 wt. % (or about 0.5 wt. %) or less, 0.1 wt. % (or about 0.1 wt. %) or less or 0.01 wt. % (or about 0.01 wt. %) or less of impurities, or any range between any of these values. Impurities may be understood as elements or compositions that may be included in the alloys due to inclusion in the feedstock components, through introduction in the manufacturing process.


Further, the M content identified in all of the compositions described in the above paragraphs may be the balance of the composition, or alternatively, where M is provided as the balance, the balance of the composition may comprise M and other elements. In some embodiments, the balance may consist essentially of M and may include incidental impurities.


Thermodynamic Criteria

In some embodiments of this disclosure, alloys can be described fully by equilibrium or near equilibrium thermodynamic parameters. The alloys can meet some, or all, of the described thermodynamic criteria.


In typical MCrAlY alloy systems, the size of the individual phases are on the order of 5 μm-50 μm if not larger. This disclosure identifies alloys that form multiple matrix phases (a face centered cubic (FCC) metal, body centered cubic metal (BCC) metal, or an ordered structure in which two simple cubic sublattices interpenetrate each other (B2 ordered phase)) on the order of 10 nm-100 nm (or about 10 nm-about 100 nm). In a B2 ordered phase, one of the sublattices may be occupied by one element, while the other sublattice may be occupied by another element. The B2 ordered phase is distinguishable from a disordered phase, in which the sublattice positions may be occupied without or less long range order relative to the B2 ordered phase, e.g., randomly, by both elements. The B2 ordered phase can have a crystal structure such that a substantially 1:1 stoichiometry can exist between atomic species. In some of the embodiments described, one of the atomic species is aluminum (Al) and another one of the atomic species can be a transition metal such as iron (Fe), chromium (Cr), nickel (Ni), and cobalt (Co). In some embodiments, the B2 ordered phase structure is two interpenetrating BCC latices. In some embodiments, the BCC structure is entirely occupied by Al atoms and the other lattice contains a distribution of certain transition metals as described above. This fine microstructure can be defined thermodynamically by looking at two factors: 1) the compositional proximity between any two matrix phases when they form and 2) the formation temperature delta between the two phases. The compositional proximity may be determined in analyzing how similar the compositions are of two phases in an alloy. Typically, phases that have different crystal structures such as FCC and BCC have very different compositions, but not in the case of some MCrAlY alloys. The grain size of an alloy can be estimated by using the cosine similarity equation (FIG. 1) and by looking at the temperature gap between the formation of the B2 ordered phase and the next matrix phase. As described herein, B2 formation delta refers to a temperature gap between the formation temperature of the B2 ordered phase and the formation temperature of a disordered phase that is immediately adjacent to the B2 ordered phase on a temperature axis of a phase diagram. Another phase that is immediately adjacent to the B2 ordered phase on the temperature axis of the phase diagram may be any disordered metallic phase, including BCC or FCC phases. The cosine similarity considers each phase as a compositional vector. Per the equation in FIG. 1, A is the compositional vector corresponding to the composition of the B2 ordered phase and B is the compositional vector corresponding to the disordered metallic phase. Per the cosine similarity equation as Cos p, or the proximity, approaches 1, the matrix compositions are increasingly similar.


In embodiments of the disclosure, the first and second matrix phase compositional proximity of the alloy can be 85% (or about 85%) or higher. In some embodiments, the first and second matrix phase compositional proximity of the alloy can be 90%, or about 90%, or higher. In some embodiments, the first and second matrix phase compositional proximity of the alloy can be 95%, or about 95%, or higher.


In some embodiments, the B2 Formation Delta can have a range of 0 K to 150 K (or about 0 K to about 150 K). In some embodiments, the B2 formation delta has a range of 25 K to 80 K (or about 25 K to about 80 K).


In some embodiments, the B2 ordered phase can comprise 40% (or about 40%) or greater of the total microstructure at 1300 K. In some embodiments, the B2 ordered phase can comprise 45% (or about 45%) or greater of the total microstructure at 1300 K. In some embodiments, the B2 ordered phase can comprise 50% (or about 50%) or greater of the total microstructure at 1300 K.


Sometimes hardphases such as carbides, borides and nitrides can be introduced to the alloy via mechanical blending for the purpose of increased wear resistance. In some embodiments, the formation of in-situ phases are precipitated on a fine scale during the atomization process. In some embodiments, the phases are more oxidation resistant than the metal itself which includes but is not limited to carbides, borides, nitrides, intermetallics, oxides, and silicides. Without limitation, oxidation resistance can be measured, e.g., by measuring an increase in the weight of a sample being studied (because of oxygen uptake by the metal), or a weight loss after removal of the oxide from the surface of the sample.


In some embodiments, the total mole fraction of oxidation resistant phases that form at 1300 K can be 5% (or about 5%) or greater. In some embodiments, the total mole fraction of oxidation resistant phases that form at 1300K can be 10% (or about 10%) or greater. In some embodiments, the total mole fraction of oxidation resistant phases that form at 1300 K can be 15% (or about 15%) or greater. In some embodiments, the total mole fraction of oxidation resistant phases that form at 1300 K can be 20% (or about 20%) or greater. In some embodiments, these oxidation resistant phases can include carbides, e.g., chromium carbides. For example, the oxidation resistant phases can include M7C3 or M23C6 carbides.


In some embodiments, mole % or mole fraction can describe an amount of atoms in the material share a characteristic. As a non-limiting example, if 40% of the atoms of a material are of a particular phase, the mole % of that phase is 40%. Mole % is a typical unit used in modeling, e.g., Calphad modeling. Calphad modeling is a phenomenological approach for calculating thermodynamic and kinetic properties of multicomponent materials systems.


In some embodiments, the alloy can have a total mole fraction of oxidation resistant phases that form at 1300 K of 5% (or about 5%) or greater and additionally the first and second matrix phase compositional proximity can be 85% (or about 85%) or higher. In such embodiments, the microstructure can combine both a fine scale structure and oxidation resistant precipitates. The following Table 2 illustrates certain measured thermodynamic criteria.









TABLE 2







Thermodynamics












1300 Total
B2





Oxidation
Formation
B2 @
1 + 2 Prox



Resistant Phases
Delta K
1300 K
Wt %















P118-X1

1735
100
1


P118-X2

640
100
97.4


P118-X3

1135
100
96.9


P118-X4


0
95.1


P118-X5

45
57.2
99.2


P118-X6

80
73.9
97.3


P118-X7

55
71.2
99.6


P118-X8

350
95
99.6


P118-X9

65
72.6
99


P118-X10

1105
100
99.9


P118-X11
10
60
50.5
89.6


P118-X12
15.9
70
51.7
90.5


P118-X13
19.8
75
51.7
93.5


P118-X14
9.9
5
34.1
94.7


P118-X15
16
25
35.2
96.5


P118-X16
20
25
35.7
95.8









Microstructural Criteria

In some embodiments, alloys can be described by their microstructural characteristics. The alloys can meet some, or all, of the described microstructural criteria.


In some embodiments, alloys form multiple matrix phases (a FCC metal, BCC metal, or B2 ordered phase) on the order of 10 nm-100 nm (or about 10 nm-about 100 nm), discussed below as fine scale phases. In some embodiments, this fine microstructure is seen in samples produced via arc melting which can have a cooling rate of approximately 5-20 degrees Celsius per second.


In some embodiments, the fine scale phases can make up 85% (or about 85%) or greater of the matrix. In some embodiments, the fine scale phases can make up 90% (or about 90%) or greater of the matrix. In some embodiments, the fine scale phases can make up 95% (or about 95%) or greater of the matrix.


In some embodiments, the B2 ordered phase can comprise 40% (or about 40%) or greater of the total microstructure. In some embodiments, the B2 ordered phase can comprise 45% (or about 45%) or greater of the total microstructure. In some embodiments, the B2 ordered phase can comprise 50% (or about 50%) or greater of the total microstructure.


In some embodiments, the total volume fraction of oxidation resistant phases can be 5% (or about 5%) or greater. In some embodiments, the total volume fraction of oxidation resistant phases can be 10% (or about 10%) or greater. In some embodiments, the total volume fraction of oxidation resistant phases can be 15% (or about 15%) or greater. In some embodiments, the total volume fraction of oxidation resistant phases can be 20% (or about 20%) or greater.


In some embodiments, oxidation resistant phases can be chromium carbides. In some embodiments, the oxidation resistant phases can be M7C3 or M23C6 carbides.


In some embodiments, the total volume fraction of oxidation resistant phases can be 5% (or about 5%) or greater while also maintaining a matrix consisting of 85% (or about 85%) or greater fraction of fine scale phases. In such embodiments, the microstructure will combine both a fine scale structure and oxidation resistant precipitates.


Performance

The performance of MCrAlY bond coats can be characterized by their Furnace Cycle Testing (FCT) results. Samples of the MCrAlY with a TBC topcoat are subjected to 60 min in the furnace at a predetermined temperature (1150° C. typically) and then removed and air quenched for 10 min to complete a single cycle. Samples are determined to have failed when the TBC has spalled or broken, typically due to overgrowth of the TGO and results are reported in cycles to failure.


In some embodiments, the alloy shows an improved cycle lifetime of 30% or more compared to Diamalloy® 4700 during FCT testing at 1150° C. In some embodiments, the alloy shows an improved cycle lifetime of 35% or more compared to Diamalloy® 4700 during FCT testing at 1150° C. In some embodiments, the alloy shows an improved cycle lifetime of 40% or more compared to Diamalloy® 4700 during FCT testing at 1150° C.


For example, Diamalloy® 4700 exhibits 235 cycles before failure. In some embodiments, the disclosed alloys can exhibit>270 cycles before failure. In some embodiments, the disclosed alloys can exhibit>300 cycles before failure. In some embodiments, the disclosed alloys can exhibit>330 cycles before failure. In some embodiments, the disclose alloys can exhibit>340 cycles before failure.


EXAMPLES

In some embodiments, an alloy containing a fine microstructure is described. For this case, P118-X5 can be used as an example and compared to a typical MCrAlY named Diamalloy® 4700.


First, the thermodynamic properties of the two alloys can be compared. P118-X5 and Diamalloy® 4700 have a B2 order phase fraction at 1300 K of 57.2% (2.1 of FIG. 2) and 40.7% (3.1 of FIG. 3) and compositional matrix phase proximities that are fairly similar to one another at values of 99.2% and 97.1% respectively. The key difference is that the B2 formation delta for P118-X5 is 45K (2.2 of FIG. 2) whereas the B2 ordered phase forms second in Diamalloy® 4700 and thus has a B2 formation delta of −10K (3.2 of FIG. 3). Thus, P118-X5 forms a fine scale microstructure but Diamalloy® 4700 does not.


The analysis of the microstructures for each alloy confirms what the thermodynamics predicts, P118-X5 forms a fine microstructure whereas Diamalloy® 4700 does not. As seen in FIG. 4, the microstructure of P118-X5 contains the matrix phases of B2 ordered, BCC metal and FCC metal that are all within the range of 10 nm-100 nm resulting in a 100% fine scale microstructure. Diamalloy® 4700 on the other hand forms a FCC metal matrix with B2 phases forming in a lamellar fashion resulting in phases that are much coarser and in the range of 5 m to 50 m as shown in FIG. 5.


Lastly, the performance of the alloys can be compared to one another. P118-X5 saw an improvement in cycle lifetime of approximately 43% over Diamalloy® 4700.


In some embodiments, a MCrAlY type alloy is described that forms a fine scale microstructure while also precipitating oxidation resistant phases. P118-X11 can be used as an example to describe this embodiment thermodynamically and microstructurally.



FIG. 6 is the phase diagram for P118-X11. Here the B2 fraction at 1300K is 50.5% (6.1), the B2 formation delta is 60K (6.2) and the compositional proximity is measured to 89.6%, which indicates that this alloy will likely form a fine scale microstructure. In addition to these criteria, P118-X11 forms M7C3 type complex chromium carbides which are characterized as an oxidation resistant phase. The total mole fraction of oxidation resistant phases for P118-X11 at 1300K is roughly 10% (6.3).


Next, a microstructural analysis took place on an arc melted sample of P118-X11 and to see if a fine microstructure was formed in the matrix. As FIG. 7 shows, the matrix consists of a fine microstructure of B2 ordered and BCC metal phases with sizes in the range of 10 nm-100 nm. Additionally in FIG. 8, it is shown that approximately 10% volume fraction of coarser complex chromium carbides precipitate as the oxidation resistant phase (8.1). The favorable oxidation behavior at 1150° C. associated with Cr7C3 precipitates in the microstructure is not intuitive as Cr7C3 alone is known to decompose at temperatures of around 1000° C.


In further experiments P118-X5 was again compared against typical McrAlY compositions commercially known as Diamalloy® 4700 (nominally in wt. % Ni-32 Co-38-5 Cr-21 Al-8 Y-0.5), and Amdry®386 (nominally in wt. % Ni 47.6 Co-22 Cr-17 Al-12 Y-0.5 Si-0.4 Hf-0.5). The coatings were sprayed onto a Hastelloy X substrate with a MCrAlY thickness of 300 μm followed by a top layer of a standard 7 yttria stabilized zirconia thermal barrier coating. The resultant coating was then heat treated in a vacuum at 1080° C. for 4 hrs. Finally, the coatings were tested in standard furnace cycling testing (FCT) whereby 1150° C. was the high temperature portion of the cycle and the coatings were in a fan cooled room temperature environment at the low temperature portion of the cycle.


The P118-X6 alloy had an FCT lifetime of 374 cycles with a standard deviation of 51 cycles. The P118-X6 had an 18.7% increased cycle lifetime over Diamalloy® 4700 and P118-X6 additionally had more consistent performance: 51 cycle standard deviation in P118-X6 vs. 131 cycle standard deviation for Diamalloy® 4700. The P118-X6 had a 44% increased cycle lifetime over Amdry® 386.


Another inherent benefit of the P118-X6 is the reduction in cobalt and nickel content of the alloy in comparison to Diamllay® 4700, Amdry® 386 and the typical portfolio of MCrAlY compositions used by industry today. In some embodiments the combined nickel and cobalt content is below 60 wt. %, in preferred embodiments the combined nickel and cobalt content is below 55 wt. % In some embodiments, the combined nickel and cobalt content is below 50 wt. %.


Another benefit of the P118-X6 composition is the ability to achieve good performance without the use of expensive rare earth additions. Rare earth elements most commonly used in MCrAlY alloys include ytrrium. rhenium, hafnium, and tantalum. In some embodiments, the rare earth content is at or below 2 wt. %. In some embodiments, the rare earth content is at or below 1 wt. %, In some still preferred embodiments, the rare earth content is at or below 0.5 wt. %. In some embodiments, no rare earth elements are used other than yttrium


Applications for Use

MCrAlY alloys as described above can be used in a variety of applications and industries. Some non-limiting examples of applications of use include:


Upstream oil and gas applications include the following components and coatings for the following components: process vessels and coating for process vessels including steam generation equipment, amine vessels, distillation towers, cyclones, catalytic crackers, general refinery piping, corrosion under insulation protection, sulfur recovery units, convection hoods, sour stripper lines, scrubbers, hydrocarbon drums, and other refinery equipment and vessels.


Power generation applications include the following components and coatings for the following components: boiler tubes, precipitators, fireboxes, turbines, generators, cooling towers, condensers, chutes and troughs, augers, bag houses, ducts, ID fans, coal piping, and other power generation components.


Steel applications include the following components and coatings for the following components: cold rolling mills, hot rolling mills, wire rod mills, galvanizing lines, continue pickling lines, continuous casting rolls and other steel mill rolls, and other steel applications.


Aerospace applications include the following components and coatings for the following components: bond coats for thermal barrier coatings and/or environmental barrier coatings, material constituents for abradables coatings, and general coatings for oxidation resistance.


The alloys described in this patent can be produced and or deposited in a variety of techniques effectively. Some non-limiting examples of processes include:


Thermal spray process including those using a wire feedstock such as twin wire arc, spray, high velocity arc spray, combustion spray and those using a powder feedstock such as high velocity oxygen fuel, high velocity air spray, plasma spray including atmospheric and vacuum, detonation gun spray, and cold spray. Wire feedstock can be in the form of a metal core wire, solid wire, or flux core wire. Powder feedstock can be either a single homogenous alloy or a combination of multiple alloy powder which result in the desired chemistry when melted together.


Welding processes including those using a wire feedstock including but not limited to metal inert gas (MIG) welding, tungsten inert gas (TIG) welding, arc welding, submerged arc welding, open arc welding, bulk welding, laser cladding, and those using a powder feedstock including but not limited to laser cladding, ultra-high speed lasers cladding (EHLA), and plasma transferred arc welding. Wire feedstock can be in the form of a metal core wire, solid wire, or flux core wire. Powder feedstock can be either a single homogenous alloy or a combination of multiple alloy powder which result in the desired chemistry when melted together.


Post processing techniques including but not limited to rolling, forging, surface treatments such as carburizing, nitriding, carbonitriding, heat treatments including but not limited to austenitizing, normalizing, annealing, stress relieving, tempering, aging, quenching, cryogenic treatments, flame hardening, induction hardening, differential hardening, case hardening, decarburization, machining, grinding, cold working, work hardening, and welding.


From the foregoing description, it will be appreciated that inventive products and approaches for bond coat alloys are disclosed. While several components, techniques and aspects have been described with a certain degree of particularity, it is manifest that many changes can be made in the specific designs, constructions and methodology herein above described without departing from the spirit and scope of this disclosure.


Certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as any sub-combination or variation of any sub-combination.


Moreover, while methods may be depicted in the drawings or described in the specification in a particular order, such methods need not be performed in the particular order shown or in sequential order, and that all methods need not be performed, to achieve desirable results. Other methods that are not depicted or described can be incorporated in the example methods and processes. For example, one or more additional methods can be performed before, after, simultaneously, or between any of the described methods. Further, the methods may be rearranged or reordered in other implementations. Also, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated together in a single product or packaged into multiple products. Additionally, other implementations are within the scope of this disclosure.


Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include or do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments.


Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z.


Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than or equal to 10% of, within less than or equal to 5% of, within less than or equal to 1% of, within less than or equal to 0.1% of, and within less than or equal to 0.01% of the stated amount. If the stated amount is 0 (e.g., none, having no), the above recited ranges can be specific ranges, and not within a particular % of the value. For example, within less than or equal to 10 wt./vol. % of, within less than or equal to 5 wt./vol. % of, within less than or equal to 1 wt./vol. % of, within less than or equal to 0.1 wt./vol. % of, and within less than or equal to 0.01 wt./vol. % of the stated amount.


Some embodiments have been described in connection with the accompanying drawings. The figures are drawn to scale, but such scale should not be limiting, since dimensions and proportions other than what are shown are contemplated and are within the scope of the disclosed inventions. Distances, angles, etc. are merely illustrative and do not necessarily bear an exact relationship to actual dimensions and layout of the devices illustrated. Components can be added, removed, and/or rearranged. Further, the disclosure herein of any particular feature, aspect, method, property, characteristic, quality, attribute, element, or the like in connection with various embodiments can be used in all other embodiments set forth herein. Additionally, it will be recognized that any methods described herein may be practiced using any device suitable for performing the recited steps.


While a number of embodiments and variations thereof have been described in detail, other modifications and methods of using the same will be apparent to those of skill in the art. Accordingly, it should be understood that various applications, modifications, materials, and substitutions can be made of equivalents without departing from the unique and inventive disclosure herein or the scope of the claims.

Claims
  • 1. A feedstock material, comprising: a composition that comprises, in weight percent (wt. %): nickel: 18-31;cobalt: 18-31;iron: 18-31;chromium: 16-27; andaluminum: 2-13; anda microstructure that comprises a B2 ordered phase and a disordered metallic phase,wherein the disordered metallic phase comprises a BCC crystal structure or an FCC crystal structure,wherein, under equilibrium conditions, a formation temperature of the B2 ordered phase is greater than a formation temperature of the disordered metallic phase by between 0 K and 150 K, andwherein at least 85% of grains in the microstructure have a size of 100 nm or smaller.
  • 2. The feedstock material of claim 1, wherein the composition further comprises 0.25-1 wt. % yttrium.
  • 3. (canceled)
  • 4. The feedstock material of claim 1 wherein the formation temperature of the B2 ordered phase is greater than the formation temperature of the disordered metallic phase by between 25 K and 80 K under equilibrium thermodynamic conditions.
  • 5. The feedstock material of claim 1, wherein the microstructure comprises 40 mole % or more of the B2 ordered phase under thermodynamic equilibrium conditions.
  • 6. The feedstock material of claim 1, wherein the microstructure further comprises 5 mole % or greater of one or more oxidation resistant phases under thermodynamic equilibrium conditions, wherein the one or more oxidation resistant phases include a compound of a metal that has higher oxidation resistance compared to the metal and wherein the one or more oxidation resistant phases comprises chromium carbide.
  • 7. (canceled)
  • 8. A coating comprising: a composition that comprises, in weight percent (wt. %): nickel: 18-31;cobalt: 18-31;iron: 18-31;chromium: 16-27; andaluminum: 2-13; anda microstructure that comprises a B2 ordered phase and a disordered metallic phase, wherein: the disordered metallic phase comprises a BCC crystal structure or an FCC crystal structure,under equilibrium conditions, a formation temperature of the B2 ordered phase is greater than a formation temperature of the disordered metallic phase by less than 150 K, andat least 85% of grains in the microstructure have a size of 100 nm or smaller when the coating is formed by cooling from a liquid state at a rate between 5° C./sec and 20° C./sec.
  • 9. (canceled)
  • 10. The coating of claim 8, wherein the microstructure comprises at least 40 mole % of the B2 ordered phase.
  • 11. The coating of claim 8, wherein the microstructure further comprises 5 volume % or greater of one or more oxidation resistant phases, wherein the one or more oxidation resistant phases include a compound of a metal that has higher oxidation resistance compared to the metal and wherein the one or more oxidation resistant phases comprises chromium carbide.
  • 12. (canceled)
  • 13. (canceled)
  • 14. The coating of claim 8, wherein the coating is formed on a Ni-based superalloy.
  • 15. The coating of claim 8, wherein the coating has applied thereon a thermal barrier coating.
  • 16. The coating of claim 15, wherein the thermal barrier coating comprises yttria-stabilized zirconia.
  • 17. The coating of claim 8, wherein the composition further comprises 0.25-1 wt. % yttrium.
  • 18. A bond coat material comprising: M, Cr, and Al, wherein M is one or more of Ni, Co, and Fe; anda microstructure that comprises a B2 ordered phase and a disordered metallic phase,wherein the disordered metallic phase comprises a BCC or FCC crystal structure,wherein, under equilibrium conditions, a formation temperature of the B2 ordered phase is greater than formation temperature of the disordered metallic phase by between 0 K and 150 K, andwherein at least 85% of grains in the microstructure are 100 nm in size or smaller when solidified from a liquid state at a rate between 5° C./second and 20° C./second.
  • 19. (canceled)
  • 20. The bond coat material of claim 18, wherein the B2 ordered phase and the disordered metallic phase have a cosine similarity of greater than 85%.
  • 21. The bond coat material of claim 18, wherein the B2 ordered phase comprises greater than 40 mole % of the microstructure.
  • 22. The bond coat material of claim 18, wherein the microstructure further comprises 10 mole % or greater of one or more oxidation resistant phases, wherein the one or more oxidation resistant phases include a compound of a metal that has higher oxidation resistance compared to the metal and wherein the one or more oxidation resistant phases comprises chromium carbide.
  • 23. (canceled)
  • 24. The bond coat material of claim 18, wherein the bond coat material comprises in weight % (wt. %): nickel: 18-31;cobalt: 18-31;iron: 18-31;chromium: 16-27; andaluminum: 2-13.
  • 25. The bond coat material of claim 18, wherein, upon cooling from the liquid state during the formation of the bond coat material, the B2 ordered phase precipitates first, followed by the disordered metallic phase.
  • 26. The bond coat material of claim 25, further comprising: 0.1-1 wt. % yttrium.
  • 27. The bond coat material of claim 18, wherein the bond coat material is formed between a Ni-based superalloy and a thermal barrier coating.
  • 28. (canceled)
  • 29. (canceled)
  • 30. (canceled)
  • 31. (canceled)
  • 32. (canceled)
  • 33. (canceled)
  • 34. (canceled)
CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to U.S. Provisional application No. 62/151,934, filed Feb. 22, 2021, entitled “MCRALY BONDCOAT ALLOYS,” the content of which is incorporated by reference herein in its entirety.

PCT Information
Filing Document Filing Date Country Kind
PCT/US2022/070736 2/18/2022 WO
Provisional Applications (1)
Number Date Country
63151934 Feb 2021 US