CA2612881A1

CA2612881A1 - Coating system for high temperature stainless steel

Info

Publication number: CA2612881A1
Application number: CA002612881A
Authority: CA
Inventors: Konstantin K. Tzatzov; Gary Anthony Fisher; Robert Prescott; Yan Chen; Hang Zheng; Chinnia Gounder Subramanian; Andrew George Wysiekierski; Juan Manuel Mendez Acevedo; Alexander S. Gorodetsky; Edward John Redmond
Original assignee: Individual
Current assignee: Manoir Industries SAS
Priority date: 2000-06-08
Filing date: 2001-06-08
Publication date: 2001-12-08
Anticipated expiration: 2021-06-08
Also published as: CA2357407C; CA2614962A1; CA2357407A1; CA2612881C

Abstract

A method for protecting carbon steel and stainless steel, and particularly high temperature stainless steel, from coking and corrosion at elevated temperatures in corrosive environments, such as during ethylene production by pyrolysis of hydrocarbons or the reduction of oxide ores, by coating the steel with a coating of MCrAlX or MCrAlXT in which M is nickel, cobalt, iron or a mixture thereof, X
is yttrium, hafnium, zirconium, lanthanum, scandium or combination thereof, and T
is silicon, tantalum, titanium, platinum, palladium, rhenium, molybdenum, tungsten, niobium, or combination thereof. The coating and substrate preferably are heat-treated at about 1000 to 1200°C for at least about 10 minutes, preferably about 20 minutes to 24 hours, effective to metallurgically bond the overlay coating to the substrate and to form a multiphased microstructure. The coating preferably is aluminized by depositing a layer of aluminum thereon and subjecting the resulting coating to oxidation at a temperature above about 1000°C for a time effective to form an alumina surface layer. An intermediary aluminum-containing interlayer may be deposited directly onto the substrate prior to deposition of the overlay coating and is heat-treated with the coating to form a protective interlayer between the stainless steel substrate and coating to disperse nitride formation at the substrate/coating interface. Also, the coating may be deposited onto and metallurgically bonded to the substrate by plasma transferred arc deposition of atomized powder of MCrAlXT, obviating the need for a separate heat treatment.
Alternatively, a blended powder composition to produce a desired MCrAlXT alloy may be applied to the substrate.

Claims

1. A surface alloyed component comprising a high temperature stainless steel substrate tube and a coating of MCrAlXSiT alloy, where M = nickel, cobalt, iron or mixture thereof, X = yttrium, hafnium, zirconium, lanthanum, scandium, or mixture thereof, and T = tantalum, titanium, platinum, palladium, rhenium, molybdenum, tungsten, niobium or combination thereof, having about 10 to 40 wt% chromium, about 1 to 30 wt% aluminum, 0.1 to about 5 wt% X, 0 to about 40 wt% silicon, and 0.1 to about wt% T, the balance M metallurgically bonded to the stainless steel substrate tube.

2. A surface alloyed component claimed in claim 1, wherein a said MCrAlXSiT
alloy has about 10 to 25 wt% chromium, 5 to 20 wt% aluminum, 0.5 to 3 wt% X, 1 to 15 wt% silicon and 0.1 to 10 wt% T.

3. A surface alloyed component claimed in claim 2, in which X is present in the range of 0.25 to 1.5 wt%.

4. A surface alloyed component claimed in claim 2, in which silicon is present in the range of about 3 to 15 wt%.

5. A surface alloyed component claimed in claim 2, in which T is present in the range of 0.1 to 5.0 wt%.

6. A surface alloyed component claimed in claim 2, in which T is present in the range of 0.5 to 3.0 wt%.

7. A surface alloyed component claimed in claim 1, in which the thickness of the coating is from 20 µm to 6000 µm.

8. A surface alloyed component claimed in claim 1, in which the thickness of the coating is from 50 µm to 2000 µm.

9. A surface alloyed component claimed in claim 1, in which the thickness of the coating is from 80 µm to 500 µm.

10. A surface alloyed component claimed in claim 1, in which the MCrAlXSiT
alloy is NiCrAlXSi and has about 12 to 25 wt% chromium, about 4 to 15% aluminum, about 0.5 to 1.5 wt% X, 1 to about 15 wt% silicon and the balance nickel.

11. A surface alloyed component claimed in claim 2, in which the MCrAlXSiT is NiCrAlXTi and has about 12 to 25 wt% chromium, about 4 to 15% aluminum, about 0.5 to 1.5 wt% yttrium, 0.5 to about 5 wt% titanium and the balance nickel.

12. A surface alloyed component claimed in claim 2, in which the MCrAlXSiT is NiCrAlYTa and has about 12 to 25 wt% chromium, about 4 to 15 % aluminum, about 0.5 to 1.5 wt% yttrium, about 0.5 to 5 wt% tantalum and the balance nickel.

13. A surface alloyed component claimed in claim 2, in which the MCrAlXSiT is NiCrAlYPt and has about 12 to 25 wt% chromium, about 4 to 15% aluminum, about 0.5 to 1.5 wt% yttrium, about 0.5 to 5 wt% platinum and the balance nickel.

14. A surface alloyed component claimed in claim 2, in which the MCrAlXSiT is NiCrAlYPd and has about 12 to 25 w.t% chromium, about 4 to 15% aluminum, about 0.5 to 1.5 wt% yttrium, about 0.5 to 5 wt% palladium and the balance nickel.

15. A surface alloyed component claimed in claim 2, additionally comprising a surface layer of aluminum, aluminum alloy containing up to 50 wt% silicon, or aluminum alloy containing up to 60 wt% silicon, a total of up to 30 wt% of at least one of chromium and titanium, the balance being at least 20 wt% aluminum in a thickness up to about 50% of the thickness of MCrAlXSiT layer.

16. A surface alloyed component claimed in claim 13, additionally comprising a surface layer of aluminum or aluminum alloy, wherein the aluminum alloy contains 1 to about 15 wt% silicon and has a thickness of up to 20% of the MCrAlXSiT
coating.

17. A coking and corrosion resistant reactor tube for use in high temperature environments comprising an elongated tube of a high temperature stainless steel and a continuous coating metallurgically bonded on the inner surface of the elongated tube comprising a MCrAlXSiT coating wherein M is nickel, cobalt, iron or a mixture thereof, X is yttrium, hafnium, zirconium, lanthanum, scandium or combination thereof, and T is tantalum, titanium, platinum, palladium, rhenium, molybdenum, tungsten, niobium or combination thereof, and comprising, by weight, about 10 to 25% chromium, about 4 to 20% aluminum, 0.1 to about 3 wt% X, 1 to 15 wt% silicon and 0.1 to about 5 wt%
T, the balance M, deposited by physical vapor deposition, plasma thermal spray or plasma transferred arc surfacing, and wherein the MCrAlXSiT coating has a thickness of about 20 µm to 6000 µm.

18. A method for providing a protective and inert coating on carbon steel and stainless steel comprising depositing onto a steel substrate a continuous coating of a MCrAlXSi alloy, where M = nickel, cobalt or iron or mixture thereof and X =
yttrium, hafnium, zirconium, lanthanum, scandium or combination thereof, having about 10 to 40 wt% chromium, about 3 to 40 wt% aluminum, about 1 to 35 wt% silicon and 0.1 to about wt% X, the balance at least 40 wt% M by physical vapour deposition, thermal spray, plasma transferred arc, weld overlay, isostatic pressing and by slurry coating, and metallurgically bonding the coating thereto by heat treating the coating at a temperature up to 1200°C for at least 10 minutes.

19. A method as claimed in claim 18, in which the coating is comprised of at least two powders of the constituents of the MCrAlXSi partially prealloyed and blended together and deposited onto the substrate, and heated in a vacuum or an oxygen-free atmosphere to a temperature above 500 to about 1200°C for a time of at least 10 minutes effective to initiate reactive sintering and to metallurgically bond the coating as a continuous impermeable coating to the substrate.

20. A method as claimed in claim 19, in which the coating is deposited in a thickness of about 50 to 6000 µm and in which the MCrAlXSi coating comprises essentially about to 20 wt% chromium, about 4 to 20 wt% aluminum, about 5 to 20 wt% silicon, and about 0.25 to 1.5 wt% yttrium, the balance being a minimum 40 wt% nickel.

21. A method as claimed in claim 20, in which the substrate is a high chromium stainless steel having 18 to 38 wt% chromium, 18 to 48 wt% nickel, the balance iron and alloying additives and in which the coating is deposited in a thickness of about 120 to 500 µm.

22. A method as claimed in claim 21, in which the coating is deposited in a thickness of about 150 to 350 µm.

23. A method as claimed in claim 22, in which the coating is aluminized by depositing a layer of aluminum having a thickness up to about 50% of the MCrAlXSi coating onto said coating and heat-treating the aluminum layer at a soak temperature in the range of about 1000 to 1160°C for at least 10 minutes effective to establish a multiphased structure.

24. A method as claimed in claim 23, in which the layer of aluminum is deposited in a thickness of about 20% of the MCrAlXSi coating by magnetron sputtering physical vapour deposition at a temperature in the range of about 200 to 500°C.

25. A method as claimed in claim 20, in which the substrate, MCrAlYSi coating and aluminum layer are subsequently heated in an oxygen-containing atmosphere at a temperature in the range of 1000 to 1160°C for a time of at least 10 minutes effective to form a layer of %-alumina thereon.

26. A method as claimed in claim 20, in which chromium, aluminum and silicon are atomized to form a CrAlSi powder prior to blending with nickel, NiCr or NiAl powders, or combinations thereof.

27. A surface alloyed component produced by the method of claim 18.

28. A surface alloyed component produced by the method of claim 21.