JP2003535976A - Coating system for high temperature stainless steel - Google Patents

Abstract

(57) [Summary] For example, caulking and corrosion of carbon steel and stainless steel, especially high-temperature stainless steel, in a high-temperature corrosive environment such as the production of ethylene or the reduction of oxide ore by pyrolysis of hydrocarbons. A method for protecting steel from being coated with MCrAlX or MCrAlXT, where M is nickel, cobalt, iron or a mixture thereof, X is yttrium, hafnium, zirconium, lanthanum, scandium or Their combination, and T is silicon, tantalum, titanium, platinum, palladium, rhenium, molybdenum, tungsten, niobium, or a combination thereof. Preferably, the coating and the substrate are heated at about 1000-1200 ° C. for at least about 10 minutes, preferably at least about 10 minutes, where the overcoating is metallurgically bonded to the substrate and effective to form a multiphase microstructure. Heat treat for about 20 minutes to 24 hours. Preferably, the coating is aluminized by depositing a layer of aluminum over the coating, and the resulting coating is oxidized at a temperature of about 1000 ° C. for a period of time effective to form an alumina surface layer. Let it. Prior to depositing the topcoat, an intervening aluminum-containing intermediate layer can also be deposited directly on the substrate and heat treated with the coating to provide a protective intermediate layer between the stainless steel substrate and the coating. To form, thereby dispersing the nitride formed at the interface between the substrate and the coating. This coating can also be used to deposit finely ground MCrAlXT powder on a substrate by a plasma transfer arc method and bond it metallurgically to the substrate, thereby requiring a separate heat treatment. Disappears. Alternatively, a powder blend of components for producing the desired MCrAlXT alloy may be applied to the substrate.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION (i) Field of the Invention This invention relates to coating systems for forming protective surfaces on carbon steel and stainless steel, and more particularly, high temperature stainless steel tubes and The application of an alloy coating to the inner wall of the fitting to form a corrosion and erosion resistant surface, which is useful in the processing of hydrocarbons such as in the production of olefins and in the direct reduction of ores. It prevents the normal caulking. The protection systems used for carbon steel are known. For example, in oil and gas drilling, the use of protection systems improves erosion and corrosivity compared to commonly used carbon steel.

(Ii) (Background Art) Stainless steel belongs to an alloy containing iron, nickel and chromium as main components, and carbon, tungsten, niobium, titanium and molybdenum are added as additives in order to obtain specific structures and physical properties. , Manganese and silicon may be included. As main types, martensite type, ferrite type, two-phase type and austenite type are known. Austenitic stainless steel is usually used when both high strength and high corrosion resistance are required. As one of such steel materials, there is a type generally called high temperature alloy (HTA), and these are generally operated at a high temperature of 650 ° C or higher and the maximum value of about 1150 ° C which is the limit value of iron-based metals. Used in industrial processes. Mainly used austenitic alloys consist of compositions of iron, nickel and chromium, chromium in the range of 18-42% by weight, 18-42% by weight.
It contains nickel in the range of 48% by weight, a balance amount (the amount necessary to bring the total to 100%), and other alloy additives. Typically, high chromium stainless steels will contain about 31-38% by weight chromium, and low chromium stainless steels will contain about 20% chromium.
-25% by weight.

The bulk composition of HTA is designed for physical properties such as creep resistance and strength, and surface chemistry such as corrosion resistance. Corrosion can be of various types depending on the operating environment, such as carburization, oxidation, sulfidation, etc. The surface is often rich in chromium oxides (chromia) for the purpose of protecting bulk alloys. The composition of the alloy intended for such use is optimized for physical (bulk) and chemical (surface) properties. If the surface chemistry due to the alloy of the surface and the physical property due to the bulk composition can be imparted, it is expected that the material for the industrial environment under various severe use conditions will be greatly improved.

Surface alloying is possible by using various coating methods and depositing the materials in appropriate proportions in appropriate proportions on the surface of the composition. It is necessary to alloy these raw materials in a controlled manner with the bulk matrix, so that, as planned, a microstructure with the desired advantages can be obtained. To do so, it is necessary to control the interdiffusion between all components and the development of the phase as a whole. Once the surface alloy is formed, it can be activated or reactivated as desired by heat treatment using a reactive gas. Both surface alloying and surface activation require significant migration of the constituent atoms at temperatures above 700 ° C, but HTA products are designed for use at high temperatures, which makes them the most suitable for this operation. It can be said that it is suitable. This operation can also be applied to metals designed for use at lower temperatures, in which case the surface must be alloyed and then heat treated to activate it to regain its physical properties.

Surface alloys or coating systems may be designed to meet the needs of the end user by assembling the coating system from a commercially available basic alloy chemical composition as a raw material to meet a particular intended use. It is possible. Properties that can be adjusted by such system design include excellent gas corrosion resistance (carburization, oxidation, and sulphurization) during heating; adjustment of catalyst activity; and corrosion resistance during heating.

Two types of metal oxides are primarily used to protect alloys at high temperatures: chromia and alumina, and mixtures thereof. The composition of stainless steel for use at high temperatures is designed to balance good mechanical properties with good oxidation and corrosion resistance. When good oxidation resistance is required, an alloy composition capable of forming an alumina scale is preferable, whereas a composition capable of forming a chromia scale is suitable for the purpose of withstanding corrosive conditions at high temperatures. . Unfortunately, adding large amounts of aluminum and chromium to bulk alloys is incompatible with maintaining good physical properties, so it is common practice to deposit a coating containing aluminum and / or chromium on top of the bulk alloy. To produce the desired surface oxide.

One of the most severe industrial processes in terms of materials is the steam cracking of hydrocarbons (“
Cracking ") to produce an olefin such as ethylene. A hydrocarbon feedstock such as ethane, propane, butane or naphtha is mixed with steam and passed through a furnace coil made up of welded tubes and fittings. The outer wall surface of this coil is heated, and the heat is transmitted to the inner wall surface, so that 850 to 115
The hydrocarbon feedstock is pyrolyzed at a temperature of 0 ° C. to obtain the desired product mixture. A disadvantage of the side reaction in this process is the accumulation of coke on the inner wall surface of the coil. There are two main types of coke, one is catalytic coke (or fibrous coke), which is nickel and iron that act as a catalyst to grow into long filaments, and the other is amorphous coke. Then, it is generated in the gas phase and comes out from the gas flow. In the light-cracking "cracking", 80-90% of the precipitate is catalytic coke, which occupies a large surface area and collects amorphous coke together.

This coke acts as a heat insulator, and in order to maintain the throughput, the temperature of the outer wall of the tube must be raised gradually. When the accumulation of coke becomes so great that it is impossible to raise the surface temperature of the tube any further, the situation is reached in which the furnace coil is removed from the line and the coke is burned off (decoking). This decoking operation usually takes 24 to 96 hours and requires 10
Every 90 days, the operation of heavy raw materials needs to be performed at a rate of once in a considerably longer period. During decoking, no product that can be used as a product is obtained, which causes a large financial loss. In addition to that, decoking will accelerate the tube damage and shorten its life. Not only does the efficiency of operation decrease, but the formation of coke also accelerates the carburizing action, which is a kind of corrosion or erosion of the inner wall of the tube. This carburizing action occurs when carbon diffuses into the steel material and a brittle carbide phase is formed. This action causes volume expansion, which reduces strength due to embrittlement and can initiate cracking. As the carburizing action progresses, the performance of the alloy having the anti-coking property is deteriorated by generating the chromium-based scale. Under normal operating conditions, carburization proceeds to half the wall thickness of the steel tube alloy after only two years of use. Tube life typically ranges from 3 to 6 years.

It is known that aluminized steel, silica-coated steel, and manganese oxide- or chromium oxide-rich steel surfaces have the effect of inhibiting catalytic coke formation. Alonizing ™ or aluminization is a method of diffusing aluminum on the surface of an alloy by diffusion infiltration treatment or chemical vapor deposition.
This coating can produce alumina scale, which is effective in inhibiting the formation of catalytic coke and protecting it from oxidation and other types of corrosion. This coating is unstable at high temperatures like in an ethylene furnace,
Since it is brittle, it tends to come off and tends to diffuse into the base alloy matrix. Generally speaking, the diffusion and permeation treatment can deposit only one or two elements, and it is extremely difficult to deposit many elements at the same time. At the practical level, usually only a few elements, most of which are aluminum, are deposited. There has also been some research into the simultaneous precipitation of two elements, such as chromium and silicon. Another approach to diffusion coating aluminum on an alloy substrate is US Pat. No. 5,403,629 (P. Adam et al.).
Is disclosed by. This patent details a method of vapor depositing a metal intermediate layer on the surface of a metal component, such as by sputtering. Following that, a diffusion coating of aluminum is deposited on the intermediate layer.

Other diffusion coating methods have also been investigated. M. C. Meelu and M.L. H. “Processing and Physical Properties (Procece)” by Lorretto
Effect of Temperature on Time in Silicon-Titanium Diffusion Coating on IN738-Based Alloys (Thes and Properties) (The
Effect of Time at Temperature on Sil
icon-Titanium Diffusion Coating on I
N738 Base Alloy) "discloses the evaluation of Si-Ti coatings, which were deposited by diffusion permeation treatment at high temperature for extended periods of time.

There have been many previous reports on the benefits of aluminizing MCrAlX coatings on superalloys to improve their oxidation and corrosion resistance. For example, European Patent EP 897996 describes that the high temperature oxidation resistance of MCrAlY on superalloys is improved by top-coating aluminides using chemical vapor deposition. Similarly, US Pat. No. 3,874,90
No. 1 discloses a superalloy coating system that includes depositing an aluminum overcoat layer on MCrAlY using electron beam physical vapor deposition, which reduces the amount of aluminum near the surface of MCrAlY. By increasing and overcoating defects on the surface with the overcoat layer, the thermal corrosion and oxidation resistance of the coating is improved. Both of these systems relate to improving the oxidation resistance and / or high temperature corrosion resistance of superalloys by depositing MCrAlY on the superalloy. These references are not concerned with improving the anti-coking and corrosion resistance of high temperature stainless steels used in the petrochemical industry.

The difficulty in finding effective coatings is largely due to the fact that most of the applied coatings are tubes, where operation at high temperatures such as hydrocarbon pyrolysis furnaces is the norm. It has a tendency to be hard to adhere to the alloy base material. Furthermore, such coatings lack the required thermal stability, resistance to heat shock, high temperature erosion, carburization, oxidation, sulphurization, etc., and / or all. In order to make it a practical product in the production of olefins by steam cracking of hydrocarbons and direct reduction of iron ore, it must have the anti-coking and anti-carburizing properties necessary for long-term operation, as well as thermal stability, It must also have high temperature erosion resistance and thermal shock resistance.

Carbon steel is commonly used for oil and gas drilling, production and casing tube strings and tools, but carbon steel is susceptible to corrosion and erosion in harsh subterranean environments. Therefore, it is necessary to coat such a carbon steel member with a protective surface coating.

Plasma-transfer arc surfacing method (PTAS, p., Such as disclosed in US Pat. Nos. 4,878,953 and 5,624,717).
Lasma transferred red surface surfing is a technique used to apply coatings of various compositions and thicknesses to electrically conductive surfaces. This material, in the form of powder or filaments, is fed to a torch that forms an arc between the cathode and the work piece. The arc produces a plasma that raises the temperature of both the powder or filaments and the surface of the substrate, melting them into a liquid puddle that solidifies into a weld coating. By varying the feed rate of the material, the speed of the torch, the distance between the torch and the substrate, and the current passed through the arc, it is possible to adjust the thickness, microstructure, density or other properties of this coating ( P. Harris and B. L. Smith, Metal Con.
structure, 15 (1983) 661-666). This technique has been applied in many fields to prevent high temperature corrosion, for example, surface treatment of nickel-based superalloys with MCrAlY (G. A. Salzman).
), P.I. Sahoo, Proc. IV National The
rmal Spray Conference, 1991, p. 541-548
) And high chromium nickel based coatings on parts such as exhaust valves of cylinders of internal combustion engines (Denmark 165,125, US Pat. No. 5,958,
332) and so on.

Air Force Materials Laboratories
Ory) technical report AFML-TR-76-91, entitled "Reaction Sintering Process with Controlled Composition for the Production of MCrAlY Coatings (Control).
ed Composition Reaction Sintering Pr
process for Production of MCrAlY coati
technical report AFML of the Air Force Materials Research Institute.
-TR-79-4097 "Ni / Co-Cr-Al for gas turbine components.
Development and evaluation of a process for Y (MCrAlY) coating (Develo)
moment and Evaluation of Process for
Deposition of Ni / Co-Cr-AlY (MCrAlY) C
“Oatings for Gas Turbine Components)”
The process being evaluated under the title is International Harvester
Company Research Laboratory Solar Division (Solar
Division of International Harvester
Company Research Laboratory, San Diego, Calif.) And has been used to apply MCrAlY type coatings on superalloys. Gas turbine blades were coated with finely ground MCrY alloy using a slurry containing an organic binder. The turbine blade thus coated was then embedded in a diffusion penetrant consisting of aluminum oxide (Al ₂ O ₃ ), aluminum powder (Al) and ammonium chloride (NH ₄ Cl). Heating this diffusion penetrant in a controlled atmosphere with controlled time and temperature conditions produced a MCrAlY coating, which was similar to a standard PVD deposited coating. . A major problem with this approach in gas turbine applications is that the coating thickness varies and is difficult to control. In addition, Al is added to the coating by a diffusion-penetration aluminized CVD method, which is not environmentally friendly.

DISCLOSURE OF THE INVENTION From the above, the main object of the present invention is to impart beneficial properties to carbon steel and stainless steel, and in order to achieve this, the surface is alloyed and substantially To improve surface performance, for example, by minimizing the number of catalytically coked sites on the inner surface of tubes, pipes, fittings and other ancillary furnace components. It completely eliminates or reduces typical coke formation, and improves the properties of the alumina scale formed on surface alloy coatings deposited on such steels. Applications for which the alloy coatings of the invention are particularly suitable are the production of olefins by steam cracking of hydrocarbons, in particular of ethylene, and of other hydrocarbon-based products in the petrochemical industry, such as carbon of iron oxide ores. It is an application to high-temperature stainless steel used in a direct reduction method of ores, which is represented by direct reduction in an existing atmosphere.

Coating of this material on high temperature stainless steel tubes used in ethylene manufacturing furnaces was observed to improve the tube's resistance to coking, carburization and hot erosion.

Another object of the present invention is to improve the carburization resistance of HTA used in tubes, pipes, fittings and other ancillary furnace components during operation.

A further object of the present invention is to provide thermal stability, high temperature erosion resistance and heat shock resistance to provide further long-lasting performance improvement benefits from alloying surfaces under real operating conditions. It is to let.

In accordance with the present invention, a coating of MCrAlX alloy is formed on a high temperature stainless steel alloy substrate, either directly or on an intermediate layer that is intermediate, and then heat treated to establish the microstructure of the coating. There are four embodiments of surface alloy structure resulting from metallurgically bonding the coating to the material. When tubes used in ethylene furnaces were treated in this way, improvements in tube anti-coking, carburization and hot erosion resistance were noted.

In a first embodiment of the surface alloy structure of the present invention, MCrAlX (where M is nickel, cobalt, iron or a mixture thereof and X is yttrium, hafnium, zirconium, lanthanum, scandium or a mixture thereof). The coating material (which is a combination) is coated on a high temperature stainless steel alloy substrate and the MCrA
IX coating and subjecting the substrate to a suitable heat treatment.

A second embodiment of the surface alloy structure of the present invention comprises a layer of aluminum or aluminum alloyed with silicon, or a layer of aluminum alloyed with silicon and either or both chromium and titanium. On the MCrAlX coating and heat treating the composite of aluminum or aluminum alloy, the MCrAlX coating and the substrate to establish the microstructure of the coating.

A third embodiment of the surface alloy structure of the present invention involves depositing an intermediate layer on the high temperature stainless steel alloy substrate below the MCrAlX coating. The presence of nitrogen and carbon in standard high temperature stainless steel alloys can lead to the formation of brittle and undesirable nitride and carbide layers at the coating-substrate interface. Depositing an intermediate layer containing a stable nitriding agent below the MCrAlX coating acts to disperse the nitride deposition.
This is preferable to the continuous presence of the nitride layer. It can be expected that carbide precipitation and dispersion are also dispersed in this intermediate layer. Again, this is preferred over the continuous presence of a carbide layer at the coating-substrate interface. This intermediate layer is also MCrA
It is not necessary to improve the adherence of the lX coating to the substrate and to have a high level of surface conditioning required for coating deposition. The MCrAlX alloy is deposited on the intermediate layer, the aluminum layer is deposited on the MCrAlX coating, and the coating system is heat treated to add aluminum to the MCrAlX coating.
Diffusing into the coating, these layers are metallurgically bonded to each other and also to the substrate to obtain the desired metallurgical microstructure.

A fourth embodiment of the surface alloy structure of the present invention comprises a blended powder composition,
By performing the reactive sintering process directly on the substrate surface, the desired MCrAlXT
Includes forming an alloy.

In any of the above embodiments, a pre-oxidation can optionally be performed to form a protective outer layer consisting primarily of α-alumina. This α
The alumina layer is very effective in reducing or eliminating catalytic coke formation. These surface alloys are compatible with practical high temperature processes up to temperatures of up to 1150 ° C, and such conditions are applicable, for example, by steam pyrolysis of hydrocarbons as typified by ethylene production to produce olefins. This is the case when manufacturing.

Broadly speaking, the method of the present invention for providing a protective and inert coating on carbon steel and high temperature stainless steel substrates up to 1150 ° C. comprises a MCrAlX alloy on a steel substrate. To produce a continuous coating of M, where M is nickel, cobalt or iron or a mixture thereof,
X is yttrium, hafnium, zirconium, lanthanum, scandium or a combination thereof, the composition of which is 0-40% by weight of chromium and about 3-3.
0 wt% aluminum, and up to about 5.0 wt%, preferably up to 3 wt%, more preferably about 0.25 to 1.5 wt% yttrium, hafnium, zirconium, lanthanum, scandium or combinations thereof, It contains a balance amount of M. The MCrAlX alloy can be deposited by various methods including, but not limited to, thermal spraying, plasma transfer arc, physical vapor deposition, and slurry coating methods. About 1 overcoat layer and substrate
It is preferable to perform the heat treatment at an ablation heat treatment temperature in the range of 000 to 1200 ° C. for at least 10 minutes, more preferably for about 20 minutes to 24 hours.

The thickness of the deposited coating is about 50 to 500 μm, preferably about 1
20-250 μm, most preferably 150 μm, and about 200-100 on the substrate.
At a temperature in the range of 0 ° C, preferably about 450 ° C, for example magnetron sputtering deposition, the coating and substrate are heated to the desired ablation heat treatment temperature.
Preferably, the MCrAlX is NiCrAlY and contains, on a weight basis, about 12-22% chromium, about 8-15% aluminum, about 0.8-1% yttrium, and a balanced amount of nickel. .

The high temperature stainless steel base material contains, on a weight basis, 18 to 38% chromium, 18 to 48% nickel, a balanced amount of iron, and alloying additives, including high chromium. Chromium is preferably 31 to 38% by weight for stainless steel and 20 to 25% by weight for low chromium stainless steel.

In another embodiment of the invention, an aluminum layer is deposited and aluminized onto a high temperature stainless steel substrate having a continuous coating of the above MCrAlX alloy with a thickness of about 120-250 μm. The aluminum-bearing coating and the substrate are heat treated in an oxygen-free atmosphere at an ablation heat treatment temperature in the range of about 1000 to 1200 ° C. for about 20 minutes to 24 hours to allow metallurgical treatment between the coating and the substrate. To form a multi-phase microstructure. The aluminum layer deposited on the coating has a thickness of up to about 50% of the thickness of the coating, preferably up to about 20% of the thickness of the coating and a temperature in the range of about 200-500 ° C, preferably about 300 ° C. Then, for example, magnetron sputtering vapor deposition is carried out, and the coating having the alumina layer and the substrate are heated to the heat treatment temperature.

In a further embodiment of the method of the present invention, a continuous intermediate layer is first deposited on the substrate prior to coating for the purpose of diffusing the nitride or carbide layer at the coating-substrate interface. . An effective composition of the intermediate layer is about 35-4.
5% by weight aluminum, either or both titanium or chromium to a total of about 5-20% by weight, and 40-55% by weight silicon, preferably about 35-40% by weight aluminum, about 5%. ~ 15 wt% titanium and about 50-5
It contains 5% by weight of silicon, which is a co-pending application number 08 /
No. 839,831, which is incorporated herein by reference, is deposited on a high temperature stainless steel substrate by the deposition method described above, and a continuous coating is deposited on the diffusion coating. A MCrAlX alloy coating is deposited and an aluminum layer is deposited on the MCrAlX alloy coating.

This intermediate layer is formed by a physical vapor deposition method at 400 to 600 ° C. or 800 to 900.
It is preferred to precipitate at a temperature in the range of ° C, preferably either 450 ° C or 850 ° C. It is also possible to use a deposition method by thermal spraying. The intermediate layer is then heated to the cauterization temperature at a rate of temperature increase of at least 5 ° C./min, preferably 10-20 ° C./min, which establishes the microstructure of the coating. An MCrAlX coating, and preferably an aluminum layer, is deposited on this intermediate layer, for example by physical vapor deposition, and then heat treated to establish a multiphase microstructure and metallurgically bond it to the coating system.

Further, the system is heated in a continuous step or another post step in an oxygen-containing atmosphere at a temperature of about 1000 ° C. or higher, preferably in the range of about 1000 ° C. to 1160 ° C. for a suitable period of time. Then, an α-alumina surface layer can be formed thereon.

The thickness of the deposited intermediate layer is about 20 to 100 μm, preferably about 20 to 60 μm.
m. An enrichment reservoir containing a base alloy and an intermetallic compound of silicon and one or more of titanium or aluminum and elements of the base alloy at an ablation heat treatment temperature in the range of about 1030 to 1150 ° C.
heat treatment for a period of time effective to form a diffusion barrier with This intermediate layer contains about 6-10% by weight silicon, 0-5% by weight aluminum, 0-4% by weight titanium and about 25-50% by weight chromium, a balance of iron and nickel and either. A base alloy element is preferably included.

In another process for forming a similar coating system, an intermediate layer, MCr
An AlX alloy coating, and optionally an aluminum layer, are deposited in this order and heat-treated in an inert atmosphere at a cauterizing temperature in the range of about 1030 to 1160 ° C. to establish the microstructure and bond the coating.

Furthermore, the surface alloy M is deposited on the HTA in a single step without separate heat treatment.
The optional provision of a CrAlX coating is a further object of the invention.

In broad terms, embodiments of the method of the present invention for providing a protective inert coating on high temperature stainless steel include protective on top of the high temperature stainless steel. It is to provide an inert coating, as the method, on the high temperature stainless steel substrate, by plasma transfer arc deposition method,
Consisting of a continuous coating of MCrAlX alloy with a metallurgical bond, where M is nickel, cobalt or iron or a mixture thereof, and X is yttrium, hafnium, zirconium, lanthanum, scandium or combinations thereof. Wherein the composition is 0-40% by weight chromium, preferably about 10-25% by weight chromium, about 3-30% by weight aluminum, preferably about 4-20% by weight aluminum, and about 5%. It comprises up to 0.0% by weight, preferably up to 3% by weight, more preferably about 0.25 to 1.5% by weight X, a balance amount of M. The coating is about 20 μm to 6000 μm, preferably 50 μm to
It is deposited on the substrate in a thickness of 2000 μm, more preferably 80 to 500 μm.

MCrAlX is FeCrAlY with 0-25% by weight chromium, about 3-4
It may include 0% by weight aluminum, up to about 3% by weight yttrium, and a balance amount of substantially iron.

MCrAlX is NiCrAlY, based on weight, about 12-25% chromium, about 4-15% aluminum, and about 0.5-1.5% yttrium.
It is preferable if it contains a balanced amount of nickel.

In a preferred embodiment of the present invention, a dense anti-caulking NiCrAlY alloy coating is deposited in a single step on the HTA tube by plasma transfer arc deposition to provide a space between the alloy coating and the substrate. A stepwise metallurgical bond can be made. The final thickness of this coating is preferably about 0.02-6 mm. A suitable thickness is in the range of 80 to 500 μm, which allows the cost of the powder to be kept within a reasonable range and does not unnecessarily narrow the inner diameter of the tube.

The NiCrAlY alloy coating serves as an aluminum source for forming an α-alumina-based layer on the surface of the NiCrAlY alloy coating. 1 in an oxidizing gas atmosphere such as air during the process
The oxygen-containing gas is introduced or present at a temperature of 000 ° C or higher, on the substrate and the coating, or in practical use, at an operating temperature of about 1000 ° C or higher. The more complete the scale of the alumina, the better the anti-coking and corrosion resistance. Therefore, it may sometimes be possible to achieve improved performance by adding an additional step of aluminization.

However, in another embodiment of the present invention, the thickness is 50 to 2000 μm.
Aluminum, or about 60% by weight, on a high temperature stainless steel substrate having a continuous coating of the above MCrAlX alloy, preferably about 80-500 μm.
Aluminum, alloyed with up to, preferably up to about 15% by weight silicon, or at least 20% by weight aluminum up to about 60% silicon and up to about 30% total titanium and chromium, or both. Of alloyed with a layer of plasma transfer arc method, for example by thermal spraying or magnetron sputtering physical vapor deposition, up to about 50% of the coating thickness, preferably about 20% of the coating thickness. Aluminization can be carried out by depositing with a thickness. This system can be used in the next step or in a separate later step, taking an effective time to form the α-alumina surface thereon,
It can be heated in an oxygen-containing atmosphere.

A further object of the invention is to improve the performance of the coating by using MCrA
providing an IX alloy with additional silicon and / or T element, wherein the T element comprises tantalum, titanium, platinum, palladium, rhenium, molybdenum, tungsten, niobium, or a combination thereof. Selected from the group.

In this aspect of the invention, in the MCrAlXSiT alloy, M is nickel,
Cobalt, iron or a mixture thereof, X is yttrium, hafnium, zirconium, lanthanum, scandium, or a mixture thereof, T is tantalum, titanium, platinum, palladium, rhenium, molybdenum, tungsten, niobium or a combination thereof, Compositions of about 0-40 wt% chromium, about 3-30 wt% aluminum, up to about 5 wt% X, 0-40 wt% silicon, and up to about 10 wt% T, a balance amount of M. Have. MCrAlXSiT alloy is 10-25
It preferably contains about 4% to about 20% by weight aluminum, up to 3% by weight X, up to 35% by weight silicon, and up to 10% by weight T. X is present in an amount of 0.25 to 1.5% by weight, silicon is present in an amount of up to 15% by weight,
It is preferred that T is present in an amount of 0.5-8.0% by weight, and most preferably T is present in an amount of 0.5-5.0% by weight.

In a preferred embodiment, MCrAlXSi having a composition of 22 wt% Cr, 10 wt% Al, 1 wt% Y and 3 wt% Si, a balance amount of Ni.
The alloy coating promotes the formation of a Cr-carbide layer at the coating-substrate interface, which acts as an effective diffusion barrier to retain the aluminum within the coating. The presence of silicon in the MCrAlX coating also facilitates the formation of Cr-based scales by the overcoating.

And, a further object of the present invention is to apply the blended powder slurry composition to a substrate, whereby a desired MCrAlX or MCrAlXSiT is obtained.

In a preferred embodiment of this aspect of the invention, MCrAlX or MCr
A mixture of two or more powders of the components of AlXSiT is blended with a binder in an amount effective to firmly coat the work piece, and the resulting work piece coated with MCrAlX or MCrAlXSiT is then subjected to reactive sintering of the coating. Heating to a temperature at which the coating creates a sticky bond to the workpiece.

This method of the invention for providing a working inert coating on carbon steel and stainless steel at temperatures up to 1150 ° C. comprises depositing a continuous topcoat coating of MCrAlXSi alloy on a steel substrate, To form a metallurgical bond, where M is nickel, cobalt or iron or a mixture thereof, X is yttrium, hafnium, zirconium, lanthanum or a combination thereof, the composition of which is , 0-25 wt% chromium, about 3-40 wt% aluminum, about 0-35 wt% silicon and up to about 5.0 wt%, preferably about 0.25-1.5 wt% yttrium. , Hafnium, zirconium, lanthanum, scandium or combinations thereof, and a balance of at least 40
% M by weight. This overcoating can be deposited by various methods, including physical vapor deposition (PVD), thermal spraying, plasma transfer arc, to name a few.
Examples of the method include, but are not limited to, a slurry coating method, and reactive sintering is performed at the same time as or after the precipitation. If reactive sintering does not occur at the same time as the deposition, then overcoat the coating and substrate at about 500-120
Reactive sintering is initiated by heat treatment for at least 10 minutes at an ablation heat treatment temperature in the range of 0 ° C.

The addition of silicon to the blended powder results in a low melting point component in the reactive sintering process, which allows the molten alloy to wet the surface of the substrate, allowing the coating and substrate to Effective diffusion coupling is generated in the meantime. Also, by adding silicon,
It is believed to have the effect of preventing the formation of brittle carbides at the interface between the coating and the substrate. When the silicon concentration is 6% by weight or more, the silicon carbide dissolves the chromium carbide formed in the base material, but when the silicon concentration is less than 6% due to the diffusion of silicon into the base material, the carbide is randomly regenerated. It begins to precipitate.

It is also preferred to pre-react some of the components with one another, eg
Chromium, aluminum and silicon are pulverized and mixed into a CrAlSi powder which is then blended with nickel, NiCr or NiAl powder or a combination thereof. By reacting the powder in advance, the exothermic reaction rate of the powder can be suppressed, and the amount of heat generated during the reactive sintering can be reduced. The thus coated workpiece is heated to a temperature of at least about 500-1100 ° C. to initiate the reactive sintering of the coating on the workpiece substrate, and then the temperature is raised to 1200 ° C. or less to allow the coating and substrate to cool. A continuous impermeable coating bonded to the substrate is made so that no clear demarcation line is visible between the materials, resulting in a random distribution of aluminum nitride at the coating-substrate interface.

In another embodiment of the present invention, the coating has a thickness of about 50-6000 μm.
, Preferably about 120-500 μm thick, more preferably 150-350 μm, where MCrAlXSi is a blended powder of NiCrAlYSi,
Up to 20% by weight chromium, about 4-20% by weight aluminum, about 5-20% by weight
Of silicon and about 0.5-1.5% by weight yttrium, with a balance of at least 40% by weight nickel.

This high temperature stainless steel base material contains, on a weight basis, 18 to 38% chromium, 18 to 48% nickel, a balanced amount of iron and alloying additives, including high chromium. Chromium is preferably 31 to 38% by weight for stainless steel and 20 to 25% by weight for low chromium stainless steel. For use in ethylene furnaces, the workpiece substrate is preferably high temperature stainless steel.

In another embodiment of the present invention, the reaction sintering results in a thickness of about 150-500 μm.
a high temperature stainless steel substrate which is continuously surface alloyed with MCrAlXSi alloys within m, aluminum, aluminum alloys containing up to about 60% by weight, preferably up to about 15% by weight of silicon, or up to 60% by weight. Aluminide by depositing thereon a surface layer of an aluminum alloy comprising silicon and up to about 30% by weight of either or both titanium and chromium and a balance amount of at least 20% by weight of aluminum, and then preferably Heat-treat in an oxygen-free atmosphere at an ablation heat-treatment temperature in the range of about 1000-1160 ° C. for at least 10 minutes to establish a multiphase microstructure. The aluminum or aluminum alloy surface layer is preferably deposited on the overcoat layer to a thickness of up to about 50%, preferably up to about 20% of the thickness of the MCrAlXSi layer, for which purpose magnetron physical vapor deposition, for example. Depending on the method, the temperature range is about 200-5
The substrate, which is deposited in the range of 00 ° C., preferably about 300 ° C. and whose surface is alloyed with this aluminum overcoat, is heated to the cauterization temperature.

Furthermore, the system is heated in a continuous process or in a separate post-process in an oxygen-containing atmosphere at a temperature of about 1000 ° C. or higher, preferably in the range of 1000 ° C. or higher to 1160 ° C. for a suitable time. Then, an α-alumina surface layer can be formed thereon.

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described with reference to FIGS. 1 and 2 of the drawings. It can be seen that the MCrAlX coating is continuously deposited on the high temperature austenitic stainless steel substrate and is metallurgically and firmly bonded. MCr of the present invention
In the AlX alloy, M is a metal selected from the group consisting of iron, nickel and cobalt or mixtures thereof, and X is an element selected from the group consisting of yttrium, hafnium, zirconium, lanthanum and scandium or combinations thereof. And, on a weight basis, about 10-25% chromium, about 8-15% aluminum and up to about 3%, preferably about 0.25-1.5% yttrium, hafnium, zirconium, lanthanum, scandium, or Contains a combination of them, a balanced amount of iron, nickel or cobalt. When these elements coexist, the growth rate of the oxide decreases, the mechanical strength of the oxide scale increases, and it acts as a scavenger of sulfur. The composition of this high temperature stainless steel substrate is iron, nickel and chromium, based on weight, 18-42% chromium, 18-48% nickel,
It contains balanced amounts of iron and other alloying additives, typically about 31-38% chromium in high chromium stainless steels, and about 20% in low chromium stainless steels.
Contains 25% chromium.

The substrate to which the MCrAlX coating is applied is typically high chromium or low chromium stainless steel, such as centrifugally cast or wrought tubes or fittings such as those used in ethylene furnaces, and the coating is such. It is applied to the inner surface of the product. It has been found that coating by magnetron sputtering physical vapor deposition provides a continuous, uniform thickness and dense coating over the entire inner surface of the tube or fitting.

By magnetron sputtering, a temperature in the range of about 200 to 1000 ° C.,
The coating is deposited on the substrate, preferably at about 450 ° C., as a continuous layer having a substantially uniform thickness of about 50-350 μm, preferably about 150 μm. Heating the coating in an oxygen-free atmosphere at a cauterizing temperature in the range of 1000-1200 ° C. for about 20 minutes to 24 hours produces a metallurgically adherent bond between the coating and the substrate, Multiphase microstructure develops.

This coating serves as a source of aluminum for forming an α-alumina-based layer on the surface thereof, for which an oxygen-containing gas such as air at a temperature of about 1000 ° C. or higher is separately processed. The oxygen-containing gas is introduced onto a substrate and a coating which are heated to a temperature of 1000 ° C. or higher in an atmosphere of an oxidizing gas such as air, or at an operating temperature of about 1000 ° C. or higher when used in practice. Introduce or exist.

A second embodiment of the present invention will be described with reference to FIGS. 3 and 4. In the same manner as above, a coating of MCrAlX was deposited on the high temperature stainless steel by magnetron sputtering to a substantially uniform thickness of about 50-350 μm, preferably about 1 μm.
Precipitate to a thickness of 50 μm. Aluminum, an aluminum alloy containing up to about 60% by weight, preferably up to about 15% by weight of silicon, or up to 60% by weight of silicon and up to about 30% by weight of titanium and / or chromium and a balance amount. A uniform layer of an aluminum alloy containing at least 20% by weight of aluminum is deposited on the MCrAlX coating, for example using magnetron sputtering at a temperature in the range of about 200-500 ° C, preferably about 300 ° C. , Deposited in an amount of up to about 50% of the coating thickness, preferably up to about 20% of the coating thickness. The substrate, coating, and aluminum layer are applied in an oxygen-free atmosphere, such as a vacuum, 1
000-1200 ° C cauterization heat treatment temperature for at least about 10 minutes, preferably about 20
Heating from minutes to 24 hours creates a metallurgical bond between the coating and substrate,
As the multiphase microstructure develops and the aluminum layer diffuses into the coating, it is then preferably for at least 20 minutes in an oxidizing atmosphere such as an oxygen containing gas.
The stepwise heating, preferably for 20 minutes to 4 hours, oxidizes the aluminum-rich layer and forms an adherent α-alumina-based layer on it with a uniform thickness.
The oxidation of the aluminum layer can be carried out in a separate step later, and the composite coating is heated in an oxidizing atmosphere, typically to a temperature of about 1000 ° C. or higher,
Preferably, the α-alumina layer is formed in the range of about 1000 to 1150 ° C., or in practical operation, it is possible to cause oxidation in an oxidizing atmosphere at a temperature of about 1000 ° C. or higher.

The presence of the aluminum layer on the coating acts as a supplemental source of aluminum for the MCrAlX coating and can maintain an effective continuous alumina layer during practical operation. When aluminum diffuses into the coating,
Covering the small structural defects that were present in the coating, while increasing the surface of the coating near the surface of the aluminum, alters the oxide growth mechanism and protects catalytic sites (such as Ni) on the alumina scale. -Oxide)
The number of

A third embodiment of the present invention will be described with reference to FIGS. According to this embodiment of the process of the invention, about 35-45% by weight of aluminum, about 5-5% in total.
Titanium or chromium, or both, at 20% by weight, and 40-55
% By weight of silicon, preferably about 35-40% by weight of aluminum, either or both of titanium or chromium to a total of about 5-15% by weight and about 5%.
A continuous aluminium-containing intermediate layer containing 0-55% by weight of silicon,
A MCrAlX alloy deposited on a high temperature stainless steel based alloy substrate and continuous onto this intermediate layer in a manner similar to that described in copending application Serial No. 08 / 839,831. The coating is deposited and aluminum or aluminum alloy containing nickel aluminide is deposited on the overcoated alloy coating.

In this embodiment, the aluminum in the interlayer can combine with the nitrogen in the substrate to form a dispersion of aluminum nitride deposits, thereby trapping the nitrogen released from the substrate. Becomes

This intermediate layer is formed by a physical vapor deposition method at 400 to 600 ° C. or 800 to 900.
It is preferred to precipitate at a temperature in the range of ° C, preferably either 450 ° C or 850 ° C. The intermediate layer is then heated to the cauterization temperature at a rate of temperature increase of at least 5 ° C / min, preferably 10-20 ° C / min, and the microstructure of the coating is established. The MCrAlX coating, and preferably an aluminum layer, is deposited by physical vapor deposition on this intermediate layer and then heat treated to establish a multiphase microstructure and to metallurgically bond to the coating.

The thickness of the deposited intermediate layer is about 20 to 100 μm, preferably about 20 to 60 μm.
m. The intermediate layer, the MCrAlX coating with the aluminum layer, and the base alloy of the substrate are provided with a base alloy and one or more of the elements of silicon and titanium or aluminum and the base alloy at a cauterizing temperature in the range of about 1030 to 1180 ° C. And heat treatment for a time effective to form an intermediate layer with the coating containing the intermetallic compound. The intermediate layer after this heat treatment has about 6 to 10
% By weight of silicon, 0-5% by weight of aluminum, 0-4% by weight of titanium and about 25-50% by weight of chromium, a balance of iron and nickel and any base alloying elements. Is preferred.

In order for the final coating to be well layered and adherent, this intermediate layer must be subjected to a suitable heat treatment. For example, 10% by weight titanium, 40
A coating containing wt% aluminum and 50 wt% silicon is deposited in the temperature range 400-500 ° C, preferably about 450 ° C, using sputtering as the process for deposition. It is possible to deposit the coating at temperatures as high as 1000 ° C., but there is little merit of coating at such high temperatures unless subsequently heat-treated in the same furnace. About 5 during this heat treatment
From 00 ° C to within 5 ° C of the maximum temperature, the rate of temperature increase should be at least 5 ° C / min, typically 10 ° C to 20 ° C / min.

At temperatures between about 1130 ° C. and about 1150 ° C., final segregation of the coating into layers occurs. Although the final microstructure is highly temperature sensitive, it is less sensitive to time at that temperature for at least about 10 minutes, preferably about 20 minutes to 2 hours. However, if the time at the final temperature is extremely short, eg 10 minutes or less, another less preferred microstructure results. At the lower limit of this temperature range, 1130 ° C, voids may still form. The optimum temperature range for the final cauterization heat treatment is 1135 ° C to 1145 ° C for at least about 20 minutes, preferably about 3 minutes.
Take 0 minutes to 2 hours. The higher the temperature, the more unstable the generated diffusion barrier becomes, and at 1150 ° C., silicon diffuses inward and is rapidly destroyed. Above this temperature, a downward diffusion of aluminum also occurs, resulting in an aluminum content of 5
% Or less. However, up to 1160 ° C., a sufficient aluminum content is maintained for the dispersion of the nitride.

If the stainless steel substrate is a forged or cast low chromium alloy substrate containing 20 to 25% by weight of chromium, the temperature gradient is the same as that of the high chromium alloy substrate.
It should be 20 ° C./min, provided that the preferred cauterization temperature is 1030 to 1160.
Within the range of ° C. In this embodiment, diffusion barriers containing chromium silicide are not formed due to the low chromium content in the base alloy. Chromium content is 20-25
Weight percent alloys include Inco 800 ™ series alloys such as 88H ™, 800HT ™ and 803 ™. The minimum required heating rate gradient is independent of the base alloy composition.

A further embodiment of the invention will be described with reference to FIG. In this embodiment of the method of the present invention, an intermediate layer of NiCr or TiAlSi alloy is magnetron sputtered onto a high temperature stainless steel substrate to about 20-100 μm.
The MCrAlX coating on the intermediate layer by one or two successive coatings, and heat treating the resulting coated substrate at a temperature in the range of 1000-1180 ° C. , The coating was metallurgically bonded.

These embodiments of the method of the present invention are illustrated by the following non-limiting examples.

Tubes and specimens of 25Cr35Ni (800H, 803, HPM, HK4M) and some 35Cr45Ni alloys were coated with the MCrAlX embodiment of the present invention using magnetron sputtering physical vapor deposition. The coated sample was vacuum coated to promote interfacial adhesion of the coating to the substrate by metallurgical bonding and to develop a metallurgical structure of fine grains, and then an aluminum surface coating on the coating. Was subjected to a high temperature heat treatment in an oxidizing atmosphere so as to form an oxide outer layer surface having anti-coking properties. Also using a coating method using magnetron sputtering, the outermost surface layer of aluminum is deposited, the aluminum content of the MCrAlX coating is increased, and the performance of the coating to regenerate the protective oxide surface layer is improved, and at the same time the coating is performed. Covering the small structural defects in it reduced the number of catalytic sites on the alumina scale.

When coating a certain type of centrifugally cast 25Cr-35Ni / 35Cr-45Ni alloy, an aluminum-bearing diffusion coating represented by a TiAlSi alloy is deposited on the substrate to form the substrate and aluminized coating. It acted as an intermediate layer between and to protect the coating from nitrogen diffusion out of the cast alloy. Alternatively, an intermediate layer of NiCr alloy can be used to disperse the nitride formation.

The coated and heat treated samples were tested for homogeneity, metallurgical bonding, microstructure, using standard laboratory techniques combining optical and scanning electron microscopy with energy dispersive spectroscopy. The thickness and composition were investigated. Tested to evaluate thermal stability and resistance to oxidation, carburization, heat shock, thermal fatigue and creep,
I got the data.

Small test pieces and 3 foot long tubes were tested in a simulated pyrolysis test apparatus. The temperature was 800 to 950 ° C., and the residence time was 0.4 to 3 seconds. The test time was varied from 1 to 8 hours. The performance of the coated tubes and specimens was compared to uncoated high temperature alloys, ceramics and pure nickel.

A coated tube 3 feet long and 5/8 inch outside diameter was tested in a simulated pyrolysis test apparatus. The performance of the coated tubes was compared to uncoated high temperature alloy and quartz tubes.

The coating was evenly deposited on the inner wall surface of the tube and was heat treated according to the method of the invention. Coated products vs. uncoated tubing and fittings are compared to commercially produced high chromium / nickel based centrifugally cast and wrought tubing surfaces under coking speed, carburizing, heat shock and heat cycle test conditions. Metallurgical fixing ability, and thermal erosion resistance.

Example 1 In FIGS. 1 and 2, the NiCrAlY coating 10 is 2 by weight.
Includes 2% chromium, 10% aluminum and 1% yttrium, balance amount of nickel, deposited by magnetron sputtering at 450 ° C. on Incoloy 800H ™ stainless steel substrate 12. The average thickness of the coating was 150 μm. The NiCrAlY coating and the substrate are heated in vacuum at a rate of 15 ° C./min up to 1100 ° C.,
A heat treatment of holding at 1100 ° C. for 1 hour produced a nickel aluminide precipitate phase 14 in the alloy matrix as shown in FIG.

The resulting coating was carburized in a CO / H ₂ atmosphere at 1080 ° C. for 70 16-hour cycles. This coating showed good carburizing resistance. The coating was heat stable at 1150 ° C. for 1000 hours. Although this coating exhibited excellent mechanical properties (compared to the diffusion coating), the stress-fracture test did not significantly compromise the properties of the substrate.

Example 2 Aluminized NiCrAlY coating 16 is 22% by weight.
Chrome, 10% aluminum and 1% yttrium, a balance amount of nickel, deposited by magnetron sputtering at 450 ° C. on Sandvik 800H ™ stainless steel substrate 18, The thickness of the coating was 150 to 200 μm. Magnetron sputtering an aluminum layer 22 over the coating at 450 ° C. resulted in an average thickness of the aluminum coating of about 40 μm, as shown in FIG.

The aluminized NiCrAlY coating and the substrate were vacuumed at 1100
When subjected to a heat treatment of raising the temperature to 15 ° C./min at a rate of 15 ° C./min and holding at 1100 ° C. for 1 hour, nickel aluminide phase 22 and nickel aluminide precipitation as a lower layer in the alloy matrix 26 adjacent to the stainless steel base material 18 A physical phase formed. The aluminized coating was oxidized in air for 1 hour at a temperature of about 1050 ° C. to form an α-alumina surface layer 28.

The coating thus obtained had good carburizing resistance and was able to withstand a 45 (+) 16 hour cycle in a CO / H ₂ atmosphere. This coating is 1
It had thermal stability at 150 ° C. for 500 hours. This coating 1
When subjected to a heat cycle test of 1000 cycles at 100 ° C., it showed excellent anti-coking property equivalent to that of an inert ceramic.

Example 3 In FIG. 5, the diffusion coating 30 is 10% chromium, 40% by weight.
% Aluminum and 50% silicon, which was deposited by magnetron sputtering at a temperature of 850 ° C. on a Manoir XTM ™ stainless steel substrate 32 to an average thickness of 40 μm. NiCrA
The LY coating 34 contains, by weight, 22% chromium, 10% aluminum and 1% yttrium, a balance amount of nickel, which was deposited on the diffusion coating by magnetron sputtering at about 850 ° C. The average coating thickness was 150 μm. An aluminum layer 36 was deposited on the NiCrAlY coating 34 at 450 ° C. by magnetron sputtering to give an average aluminum coating thickness of 20 μm.

The aluminized NiCrAlY coating on the diffusion coating was subjected to a heat treatment in vacuum at a rate of 15 ° C./min and held at 1150 ° C. for 1 hour, as shown in FIG. A diffusion barrier 40 was formed on the upper side, and an enriched reservoir 42 was formed adjacent to the diffusion barrier 40. The nickel aluminide phase 44 is generated when the aluminum layer diffuses inward and penetrates into the upper portion of the NiCrAY coating 46. The nickel aluminide phase 44 forms an α-alumina-based layer 48 on its surface by introducing air at the end of the vacuum heat treatment.

The coating thus obtained was kept at 1150 ° C. for 500 hours to evaluate its thermal stability and was also subjected to a heat shock test. This coating showed good thermal stability and good heat shock resistance.

Example 4 A NiCr alloy consisting of 50% Cr and 50% Ni on a weight basis was subjected to magnetron sputtering at 450 ° C. at Kubota's KHR35CW.
It was deposited on the alloy to an average thickness of 40 μm. 22% Cr by weight,
A NiCrAlY coating of 10% Al, 1% Y, and a balance amount of Ni was deposited by magnetron sputtering at 450 ° C. to an average thickness of 60 μm, and the second time, 18% Cr by weight, 15% Al, 1% Y
A balanced amount of Ni, a NiCrAlY coating, was deposited by magnetron sputtering at 450 ° C. to an average thickness of 80 μm. The resulting coating and substrate were heat treated in vacuum for 1 hour at 1150 ° C.

The thus heat-treated coating was subjected to isothermal oxidation in laboratory air for 192 hours, after which it remained relatively good. This coating also showed good mechanical properties compared to NiCrAlY without the NiCr layer.

Example 5 TiAlSi with 20% Ti, 20% Al, balance amount Si, by weight
The alloy was magnetron sputtered at 850 ° C. to produce Manio
r) It was deposited on the XM alloy to have an average thickness of 40 μm. Then, based on weight, 22% Cr, 10% Al, 1% Y, balance Ni.
The NiCrAlY alloy of was deposited by magnetron sputtering at 850 ° C. to have an average thickness of 160 μm. This coating in vacuum for 1 hour, 1
It heat-processed at 150 degreeC and formed the intermediate | middle layer shown in FIG.

The resulting coating was subjected to isothermal oxidation in laboratory air to successfully disperse the detrimental nitride phase and to protect it for up to 480 hours.

Example 6 In Figures 7-11, a continuous coating of MCrAlX was deposited on a high temperature austenitic stainless steel substrate by the plasma transfer arc method and metallurgically and firmly bonded. . In the MCrAlX alloy of the present invention, M is iron,
A metal selected from the group consisting of nickel and cobalt or mixtures thereof, X being an element selected from the group consisting of yttrium, hafnium, zirconium, lanthanum, scandium and combinations thereof, on a weight basis of about 0
-40%, preferably about 10-25% chromium, about 3-30%, preferably about 4
-20% aluminum, and up to about 5%, preferably up to 3%, more preferably about 0.5-1.5% yttrium, hafnium, zirconium, lanthanum and / or scandium, balance iron, nickel or Contains cobalt or a combination thereof.

The substrate to which MCrAlX is overcoated is typically a tube or fitting made by centrifugal casting or wrought of high chromium or low chromium stainless steel, which when coated by the plasma transfer arc deposition method. A continuous, uniform thickness over the entire length of the inner surface of the fitting,
It has been found that a dense coating is obtained.

A preferred MCrAlX is NiCrAlY, which is about 12-25% by weight.
Chromium, about 4-15% aluminum, about 0.5-1.5% yttrium,
And the balance amount is substantially made of nickel.

As a method of depositing the NiCrAlY coating, the base material of the base alloy is used as a part of the electric circuit, and the plasma transfer arc method is used to form the MCrAlX coating.
There is one in which a powder raw material having a composition is applied. In the above method, the plasma arc dissolves both the powder and the base alloy, but argon is used as a carrier and shroud gas to prevent oxidation. During deposition, the formation of molten puddle is controlled by process parameters to obtain a coating of desired thickness. Some dilution occurs as some of the base alloy melts, which affects the final composition of the coating. It also forms a transition zone between the base alloy and the coating, if desired, which results in the formation of carbides and nitrides produced by the diffusion of carbon and nitrogen at high temperatures, such as in ethylene furnace operation. Absorb in a diffused form. This greatly reduces the risk of coating delamination.

The coating thus obtained is dense and forms an alumina scale upon contact with air at elevated temperatures and also firmly adheres to the tube. In the plasma transfer arc method, a separate aluminizing step can be omitted. Further, the mass transfer can be performed very efficiently, and 80 to 90% of the raw material can be utilized in the coating, but in comparison, the efficiency of magnetron sputtering is only 25 to 30%.

There are two kinds of high temperature alloy stainless steel raw materials used as the base material, one is H46M alloy and the other is 900B alloy. The coating used was Ni
CrAlY powder, the nominal composition of which is expressed as wt%, where Al is 10, Cr is 22, Y is 1, Ni is a balance amount, and impurities are 1 wt% or less. The particle size distribution of the powder is +45 microns-106 microns. The feeding speed of powder to the gun is 30
g / min, and the arc used 100 amps and 50 volts.

As seen in FIG. 7, this coating is dense and continuous and has a smooth surface with a thickness of 4 mm or more. No defects were found to extend from the base alloy to the coating surface, but some bubbles were present near the outer surface of the coating. From the composition, part of the alloy melts and NiCrAlY becomes HTA.
The fact that it was mixed with the elements inside and diluted was found. In each case, the aluminum content was between 5 and 7% by weight. However, the sample deposited on H46M had less iron and more nickel and chromium than the sample deposited on 900B. Other elements present in the base alloy, such as silicon, niobium and manganese have also diffused into the coating, but in the weld layer 1
There was nothing that exceeded the weight percentage. None of these samples were heat treated prior to testing.

These samples were aged in air at 1150 ° C. for up to 500 hours. The sample after each aging time was taken out from the heating furnace and immersed in water to evaluate the heat shock resistance of the ensemble. Even with such treatment, none of the samples had peeling or cracks. As can be seen in FIGS. 8 and 9, there was no noticeable change in bulk microstructure with varying aging times. However, new structures developed at the free surface and interfaces. A 10 micron thick layer of alumina was formed on the outer surface, which was found to significantly reduce catalyst coke formation in the coated HTA alloy. At the voids and other internal defects, mixed oxides (Cr-Al-
A core of (Ni-YO) was deposited inside the surface layer of alumina. The oxygen attack extended to a few microns inside the coating. At the interface, a large amount of nitride, most of which was AlN, was formed, but these crystals grow in a dispersed form as seen in FIGS. 10 and 11. The number of nitrides was higher in the sample prepared from the high chromium alloy H46M, presumably due to the higher amount of dissolved nitrogen in the alloy. Even in this case, since the nitride is not agglomerated linearly or continuously, the possibility of mechanical defects is low. In this case, there is no need to deposit the intermediate layer. This is because the main purpose of the middle layer is to absorb the nitrogen coming out of the tube. The amount of aluminum in the bulk has decreased to just over 5% by weight after aging at 1150 ° C. for 500 hours, with the original aluminum diffused into the base alloy.

This embodiment of the method of the invention offers several important advantages. When NiCrAlY powder is applied to the alloy of the substrate by the plasma transfer arc method, the resulting intermediate layer has a high density, has a continuous and smooth surface, and has an adherent metallurgical bond to the HTA substrate. Form. Both the deposited nitrides and carbides are dispersed within or in the immediate vicinity of the interfacial layer, eliminating the need for heat treating the coating or providing another intermediate layer. The aluminum in the coating is fully utilized to form the alumina surface scale. Even after aging for 500 hours at 1150 ° C. in air and then heat shock test, there is almost no change in composition and bulk structure. Although the nitrides formed near the interface layer, they are dispersed and do not cause delamination of the coating. Oxidation was apparently occurring on the surface, but the attack remained on the surface, leaving sufficient aluminum to maintain the protective alumina scale. HTA
The surface layer alloy of the present invention for use is particularly useful for coating reactor tubes used in high temperature and corrosive environments such as ethylene production furnaces.

The additive silicon can be present in an amount of 0 to 40% by weight, preferably 3 to 15% by weight. The additive T can be present in an amount of 0-10% by weight, preferably 0.1-5% by weight, more preferably 0.5-3% by weight. About 12 ~
In MCrAlX consisting of 25% by weight of chromium, about 4 to 15% by weight of aluminum, about 0.5 to 1.5% by weight of yttrium and a balanced amount of nickel, preferred additive T is titanium, tantalum, Platinum or palladium, tungsten, molybdenum, niobium or rhenium. Addition of silicon to the MCrAlX coating improves resistance to both hot corrosion and oxidation. C
The addition of tantalum and tungsten to r-based coatings contributes to improved resistance to sulfidation and oxidation. The coexistence of molybdenum in an aluminum-forming alloy improves the properties of the Cr-based oxide scale formed after the aluminum has disappeared from the coating metal. The inclusion of titanium in the MCrAlX alloy composition makes the coating resistant to thermal corrosion, especially sulfide and / or
Alternatively, the resistance to halogen-containing compounds is improved. With the addition of niobium,
Since the coefficient of thermal expansion of the coating changes and matches the coefficient of thermal expansion of the substrate, the strength of the coating increases. The coexistence of palladium, platinum or rhenium improves the performance of the alumina scale and allows it to grow slowly. A preferred composition is MCrAlXSi consisting of 22 wt% Cr, 10 wt% Al, 1 wt% Y, 3 wt% Si, a balance amount of nickel.

The thickness of the MCrAlXSi or MCrAlXT topcoat coating ranges from 20 to 20.
6000 μm, preferably 50 to 2000 μm, more preferably 80 to 500 μm
Can be changed between m.

Aluminum, an aluminum alloy containing up to 50% by weight, preferably up to 15% by weight of silicon, or up to 60% by weight of silicon and up to 30% by weight of either or both titanium and chromium and a balance amount. At least about 20
A surface layer of an aluminum alloy containing wt% aluminum can be deposited on the MCrAlXSi or MCrAlXT coating in an amount up to about 50% of the coating thickness. Preferred as the top layer is an aluminum or aluminum alloy layer having a thickness of up to 20% of the thickness of the MCrAlSi or MCrAlXT topcoat coating.

An industrial example of the coating of the present invention is an anti-coking, corrosion-resistant reactor tube used in a high temperature environment, the tube being a high temperature stainless steel drawn tube and the drawn tube. Consisting of a continuous coating metallurgically bonded to the inner surface of a MCrAlXT alloy, where M is nickel, cobalt, iron or a mixture thereof,
X is yttrium, hafnium, zirconium, lanthanum, scandium or a combination thereof, T is silicon, tantalum, titanium, platinum, palladium, rhenium, molybdenum, tungsten, niobium or a combination thereof, on a weight basis, about 10-25% chromium, about 4-20% aluminum, about 3% by weight
X, and T up to about 8% by weight, and a balance amount of M to deposit the coating by physical vapor deposition, plasma spraying or plasma transfer arc surfacing, or binder coating. Of one of many methods, where the thickness of the MCrAlXT coating is about 20μ.
m to 6000 μm.

MCrAlXSi coatings in which silicon is present in an amount of 3 to 40 wt. It has been found that it can be applied by adding to an organic binder to form a slurry and coating the slurry on a substrate. The coated substrate is dried and heated in a vacuum oven to evaporate the organic binder and reaction sinter the coating with the substrate to adhere the coating to the substrate.

A preferable slurry composition contains at least two powder components of MCrAlXSi, and M of them is nickel. This powder is blended and added to an organic binder, such as an acrylic binder dissolved in an organic solvent. This nickel contains 50 to 150 μm of one or more other components.
Has a relatively small average particle size of 2 to 10 μm, and the other one or more components have a disk shape or a spherical shape.
It has an irregular shape. By having a difference in particle size and shape, after the organic binder has evaporated, the particles will interlock and stay on the substrate,
This is described below.

When the content of silicon contained in the blended powder is up to 40% by weight, the melting point of the coating is lowered to about 900 to 1150 ° C. When the silicon concentration is 6% by weight or more, the silicon carbide dissolves the chromium carbide formed in the base material, but when the silicon concentration is less than 6% due to the diffusion of silicon into the base material, the carbide is randomly regenerated. It begins to precipitate.

In this aspect of the invention, the MCrAlXSi alloy is reacted and sintered in vacuum or in an oxygen-free atmosphere by depositing two or more powders that are components of the MCrAlXSi alloy. Five types of embodiments of the surface alloy structure obtained by heating to the temperature and diffusion-bonding the alloy to the base material are shown.

In the first embodiment of the present invention, two or more kinds of powders of the components of the MCrAlYSi alloy are blended, and the surface of the processed product is subjected to hydrostatic compression molding. The compression-molded work piece of the topcoat is heated in a vacuum or oxygen-free atmosphere to cause reactive sintering. In reactive sintering, it is necessary to control the chemical activity of the components in order to avoid a sudden reaction. When the coating is formed, a reaction should also occur at temperatures such that the coating adheres to the substrate. An example of a reaction that cannot be controlled is a reaction in which a NiAl intermetallic compound is produced from Ni and Al powders. This reaction between Ni and Al begins at 800-900 ° C. The temperature rises rapidly to 1600 ° C, and NiAl is deposited on the surface of the relatively cold substrate.
Melt droplets are formed. Due to the low substrate temperature and the high chemical stability of NiAl, the molten droplets solidify rapidly and do not react with the substrate. In the present invention, the activity of the powder is adjusted in order to avoid a violent reaction between the powders. Some components, such as Si and Al, are reacted in advance to reduce their activity.
For example, finely ground CrAlSi powder may be combined and blended with Ni, NiAl and NiCr powders. This reduces the amount of heat generated during the reaction, and the reaction starts at a higher temperature. The elevated temperature causes the coating to react with the surface of the substrate, resulting in an excellent bond between the coating and the substrate. In order to create a low melting point liquid (900-1000 ° C.) between Fe and Ni, it is necessary to add Si to the coating. These liquids wet the surface of the substrate, creating a bond between the coating and the substrate. Si may also be added to prevent the formation of brittle carbides at the coating-substrate interface. When the initial concentration is set to 6% by weight or more, Si dissolves the chromium carbide existing in the base material, but when the concentration falls below 6% due to the diffusion of Si into the base material, the carbide is removed. It re-precipitates randomly.

In a second embodiment of the invention, two or more powders of the components of the MCrAlYSi alloy are blended and deposited as a coating on the surface of the workpiece, for which purpose thermal spraying, chemical vapor deposition, or , Using magnetron sputtering from a pre-sprayed cathode. The coated workpiece is then heated in a vacuum or oxygen free atmosphere to cause reactive sintering.

In a third embodiment of the present invention, two or more powders of the components of the MCrAlYSi alloy are blended and deposited on the surface of the work piece, for which the plasma transfer arc method is used. , Reaction sintering at the same time as precipitation.

In a fourth embodiment of the invention, two or more powders of the components of the MCrAlYSi alloy are blended with an effective amount of an organic binder as needed and mixed with a solvent in combination with a high viscosity carrier. Then, it is applied as a slurry to the surface of the processed product. The top-coated slurry-coated workpiece is dried and then heated in vacuum or in an oxygen-free atmosphere to cause reactive sintering.

One of the advantages of this reactive sintering process is that no clear demarcation line is formed at the boundary between the coating and the substrate. Not only does this provide a good bond between the coating and the substrate, but it also allows the brittle aluminum nitride to be randomly dispersed when using the MCrAlY alloy on the nitrogen-containing substrate. PVD
In MCrAlY coatings deposited by the method, these nitrides may form a brittle layer at the coating-substrate interface, leading to delamination of the coating 1.

This coating serves as a source of aluminum for forming an α-alumina-based layer on the surface thereof, for which an oxygen-containing gas such as air at a temperature of about 1000 ° C. or higher is separately processed. The oxygen-containing gas is introduced onto a substrate and a coating which are heated to a temperature of 1000 ° C. or higher in an atmosphere of an oxidizing gas such as air, or at an operating temperature of about 1000 ° C. or higher when used in practice. Introduce or exist.

In a fifth embodiment of the surface alloy structure of the present invention, a layer of aluminum is deposited on the MCrAlXSi surface alloy structure described above and the composite of aluminum and MCrAlXSi surface alloyed substrate is heat treated to obtain the desired Establish the coating microstructure.

It will be understood that modifications can be made to the embodiments described and described herein without departing from the scope and terms of the invention as defined by the appended claims. Should be understood.

[Brief description of drawings]

The process of the invention and the products produced thereby are illustrated by the accompanying drawings, in which:

FIG. 1 is a micrograph of a cross section of a NiCrAlY coating deposited on a stainless steel substrate.

[Fig. 2]   2 is a photomicrograph of the NiCrAlY coating shown in FIG. 1 after heat treatment.

FIG. 3 is a micrograph of a cross section of a NiCrAlY coating having an aluminum layer deposited thereon.

FIG. 4 is a micrograph of a NiCrAlY coating having an aluminum layer deposited thereon after heat treatment.

FIG. 5 is a micrograph of a diffusion coating deposited on a stainless steel substrate, a NiCrAlY coating deposited on the diffusion coating, and an aluminum layer deposited on the overcoat.

[Figure 6]   6 is a photomicrograph of the composite coating shown in FIG. 5 after heat treatment.

FIG. 7: NiC deposited by plasma transfer arc method on HTA alloy 900B
It is a microscope picture of the interface part of rAlY coating.

FIG. 8: NiCrAlY after aging in air at 1150 ° C. for 500 hours
3 is a micrograph of the upper surface of FIG.

FIG. 9 is a micrograph of a microstructure of a bulk portion after aging in air at 1150 ° C. for 500 hours.

FIG. 10: NiCrAlY after aging in air at 1150 ° C. for 500 hours
3 is a micrograph of the interface between the coating and low chromium stainless steel.

FIG. 11: NiCrAlY after aging in air at 1150 ° C. for 500 hours
3 is a photomicrograph of the interface between the coating and high chromium stainless steel.

FIG. 12: Diffusion coating and NiCrAl on stainless steel substrate after heat treatment
It is a microscope picture of the interface with Y coating.

─────────────────────────────────────────────────── ─── Continued front page    (31) Priority claim number 2,348,145 (32) Priority date May 22, 2001 (May 22, 2001) (33) Priority country Canada (CA) (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE, TR), OA (BF , BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, G M, KE, LS, MW, MZ, SD, SL, SZ, TZ , UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, B Z, CA, CH, CN, CO, CR, CU, CZ, DE , DK, DM, DZ, EC, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, I N, IS, JP, KE, KG, KP, KR, KZ, LC , LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, P L, PT, RO, RU, SD, SE, SG, SI, SK , SL, TJ, TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW (72) Inventor Fisher Gary Anthony             Canada Tea 6 E 0 P 3 Al             Bertha, Edmonton, 67 Avenue             9843 (72) Inventor Prescott Robert             Canada Tea 6 A 1 M 8 Al             Bertha, Edmonton, 77th Avenue               10425, # 302 (72) Inventor Chen Yang             Canada Tea 8 A 5 L 1 Al             Bertha, Sherwood Park, Carmel               Window 2 (72) Inventor Seng Han             Canada T6 J0 T9             Alberta, Edmonton, 41 Avenue             ー 11465, # 305 (72) Inventor Subramunian Chinnia Gounder             Canada tee 6 are 2 sea 9 a             Ruberta, Edmonton, Falconer             Road 1039 (72) Inventor Weissel Kelsky Andrew Jo             Page             Canada buoy 0 etch 1 are 0 bu             Okanagan, British Columbia             False, Oliver Ranch Road             1840, 39, Barryview Estates (72) Inventor Mendes Ace Bed Houwan Manuel             Le             Canada Tea 6 E 0 P 2 Al             Bertha, Edmonton, 67 Avenue             9712 (72) Inventor Gorodetsky Alexander S             Canada Tea 8 A 5 M 8 Al             Bata, Sherwood Park, Rainbow             U Crescent 521 (72) Inventor Redmond Edward John             Canada Tea 5 Tea 1 E 3A             Ruberta, Edmonton, NW,             Wolf Willow Point 2 F-term (reference) 4K029 AA02 BA21 BA23 BA25 BC01                       BC02 BC10 CA05 DC04 DC39                       GA01                 4K044 AA02 AA03 AB03 BA01 BA02                       BA06 BA10 BB03 BB11 BC02                       CA11 CA13 CA24 CA27 CA62 [Continued summary] Allow it to oxidize for an effective time. Topcoat coating Aluminium-containing intermediate sandwiched before depositing The layers can also be deposited directly on the substrate, Heat-treated together with stainless steel base material and coating Form a protective intermediate layer between the Disperse the nitrides that form at the interface between the substrate and the coating It This coating is also a finely ground MCrAl XT powder is deposited on the substrate by plasma transfer arc method. And metallurgically bonded to the substrate, which Therefore, it is not necessary to perform heat treatment separately. Another way To produce the desired MCrAlXT alloy You may apply the powder blend of this to a base material.

Claims (100)

[Claims] 1. A method for providing a protective coating having a non-catalytic surface on low carbon steel and stainless steel, comprising depositing a continuous coating of MCrAlX alloy on a steel substrate. Metallurgically bonded thereto, where M is nickel, cobalt or iron or a mixture thereof, X is yttrium, hafnium, zirconium, lanthanum, scandium or a combination thereof, about 0 to A method comprising 40 wt% chromium, about 3-40 wt% aluminum, and up to about 5 wt% X, a balance amount of M. 2. The substrate is high temperature stainless steel and the MCrAlX alloy is about 1
The method as claimed in claim 1, comprising 0-25 wt% chromium, about 5-20 wt% aluminum and up to about 3 wt% X, a balance amount of M. 3. The coating and metallurgy are heat treated at an ablation heat treatment temperature for a time period effective to cause a change in the multiphase microstructure and metallurgically bond the coating to the substrate. The method as claimed in claim 2, wherein the method is biologically bonded to a substrate. 4. X is present in an amount of 0.25 to 1.5% by weight, the coating is deposited to a thickness of about 50 to 500 μm and the coating and substrate are about 1000.
The method as claimed in claim 3, wherein the method is heated to a cauterization temperature in the range of -1200 ° C and held at that caustic temperature for at least about 10 minutes. 5. The MCrAlX is NiCrAlY and comprises about 12-22% by weight chromium, about 8-20% by weight aluminum and 0.8-1% by weight yttrium, a balance amount of nickel, wherein: The method as claimed in claim 4, wherein the coating is deposited on the substrate by magnetron sputtering physical vapor deposition at a temperature in the range of about 200-1000 ° C. to a thickness of about 50-350 μm. 6. Aluminum, an aluminum alloy containing up to 50% by weight of silicon, or up to 60% by weight of silicon and up to 30% by weight of titanium and / or chromium and a balance amount of at least about 20% by weight. Aluminum alloy surface layer containing aluminum at about 50% of the coating thickness.
% On the coating, and the aluminum or aluminum alloy-laden coating and the substrate are heat treated at a heat treatment temperature in an oxygen-free atmosphere to diffuse the surface layer into the coating. The method as claimed in claim 4, further comprising metallurgically bonding a coating topcoat to the substrate and optionally heat treating in a more oxidizing atmosphere to produce an alumina surface scale thereon. 7. The aluminum alloy comprises up to 15% by weight of silicon and comprises about 20%.
Aluminum or an aluminum alloy is deposited on the coating at a thickness of about 20% of the thickness of the coating using magnetron sputtering physical vapor deposition at a temperature in the range of 0-500 ° C., and in an oxidizing atmosphere at about 1000- Heat treating at a temperature in the range of 1160 ° C. for a time effective to form an alumina scale thereon,
The method as claimed in claim 6. 8. A continuous layer is deposited on a stainless steel substrate prior to depositing the MCrAlX coating to provide a continuous nitride or carbide between the stainless steel substrate and the coating at the coating-substrate interface. 7. The method as claimed in claim 6, further comprising providing an intermediate layer effective to minimize or avoid layer formation. 9. A high temperature stainless steel substrate wherein the intermediate layer comprises about 35-45% by weight aluminum, about 5-20% by weight chromium and / or titanium, and about 40-55% by weight silicon. 400-600 ° C or 800-90 on top
The intermediate layer is deposited at a temperature of 0 ° C. to a thickness of about 20 to 100 μm, and the intermediate layer is about 1 μm thick.
9. The method as claimed in claim 8, wherein the heat treatment temperature is in the range of 030 to 1180 [deg.] C. for at least about 20 minutes. 10. The stainless steel substrate comprises about 31-38% by weight chromium.
10. The method as claimed in claim 9, wherein the intermediate layer is heat treated at an ablation heat treatment temperature in the range of about 1130-1160 [deg.] C. for about 30 minutes to 2 hours. 11. The stainless steel substrate comprises about 20-25% by weight chromium,
The method as claimed in claim 9, wherein the intermediate layer is heat treated at a cauterizing temperature in the range of about 1050-1160 ° C for about 30 minutes to 2 hours. 12. The intermediate layer comprises about 35-45% by weight aluminum, a total of about 5%.
~ 15% by weight of either or both titanium and chromium, and about 50 ~
Deposited on a high temperature stainless steel substrate containing 55% by weight of silicon and depositing a continuous MCrAlX alloy coating on this intermediate layer, where M
Is nickel, cobalt or iron or a mixture thereof, X is yttrium, hafnium, zirconium, lanthanum, scandium or a combination thereof, wherein about 10 to 25% by weight chromium, about 6 to 15% by weight aluminum and Up to about 3% by weight of X, containing a balance amount of M, optionally depositing an aluminum layer on the MCrAlX alloy coating, oxygen free substrate, intermediate layer, coating and aluminum or aluminum alloy surface layer This surface layer is heat treated in the atmosphere at an ablation temperature for an effective time to diffuse into the coating to form a multi-phase microstructure that metallurgically bonds the coating and intermediate layer to the substrate. And, optionally, an alumina surface scale at a temperature above about 1000 ° C. in an oxidizing atmosphere. There is heat-treated over a period of time effective, the claimed in claim 8 To produce thereon. 13. The method as claimed in claim 12, wherein the coating and substrate are heated at an ablation heat treatment temperature in the range of about 1030 to 1180 ° C. for about 20 minutes to 24 hours. 14. An intermediate layer is deposited by magnetron sputtering physical vapor deposition at a temperature in the range of 800 to 900 ° C., the intermediate layer, MCrAlX coating having an aluminum or aluminum alloy surface layer, and a substrate having at least 5 parts. 13. The method as claimed in claim 12, wherein heating to the ablation heat treatment temperature at a heating rate of ° C / min. 15. The claim of claim 14, wherein the intermediate layer, the MCrAlX coating having an aluminum or aluminum alloy surface layer, and the substrate are heated to a cauterization temperature at a heating rate of about 10-20 ° C./min. How 16. A MCrAlX coating having an intermediate layer deposited to a thickness of about 20 to 100 μm and having an intermediate layer, an aluminum or aluminum alloy surface layer,
And the base alloy of the base material at an ablation heat treatment temperature in the range of about 1030 to 1160 ° C.
Heat treating for a time effective to form an intermediate layer between the base alloy and the enriched reservoir containing silicon and one or more of titanium or aluminum and an element of the base alloy. The method as claimed in claim 15. 17. The heat-treated intermediate layer contains about 6-10% by weight of silicon, 0-5.
17. The method as claimed in claim 16, comprising wt% aluminum, 0-4 wt% titanium and about 25-50 wt% chromium and a balance amount of iron and nickel and any base alloying elements. 18. A stainless steel substrate comprising about 31-38% by weight chromium.
18. The method as claimed in claim 17, wherein said intermediate layer is heat treated at an ablation heat treatment temperature in the range of about 1130-1160 <0> C for about 30 minutes to 2 hours. 19. A stainless steel substrate comprising about 20-25% by weight chromium.
18. The method as claimed in claim 17, wherein said intermediate layer is heat treated at an ablation heat treatment temperature in the range of about 1050-1160 <0> C for about 30 minutes to 2 hours. 20. A surface alloying component comprising a continuous coating of a stainless steel base alloy substrate and a MCrAlX alloy deposited thereon, wherein M is nickel, cobalt, iron or mixtures thereof. X is yttrium, hafnium, zirconium, lanthanum, scandium or a combination thereof, and on a weight basis, about 10-25% chromium, about 5-20% aluminum and up to about 3% yttrium, hafnium, A surface alloy containing zirconium, lanthanum, scandium or a combination thereof, and a balance amount of M, which has been heat-treated at a temperature effective to cause a MCrAlX alloy to be metallurgically bonded to a base material and to form a multiphase microstructure in the MCrAlX alloy. Ingredients. 21. X is present in an amount of 0.25 to 1.5% by weight and the coating and substrate are heated at a caustic treatment temperature in the range of about 1000 to 1180 ° C. for about 20 minutes to 24 hours. The surface alloying component claimed in 20. 22. MCrAlX is NiCrAlY, and by weight, about 12-22% chromium, about 8-13% aluminum, about 0.8-1% yttrium, and a balance amount of substantially nickel. A surface alloying component as claimed in claim 21, comprising: 23. The surface alloying component as claimed in claim 21, wherein the coating is deposited on the stainless steel substrate by magnetron sputtering. 24. The surface alloying component as claimed in claim 23, wherein the thickness of the coating is about 50-350 μm. 25. Aluminum, an aluminum alloy containing up to 50% by weight of silicon, or up to 60% by weight of silicon and up to 30% by weight of titanium and / or chromium and a balance amount of at least about 20% by weight. %
A surface layer of an aluminum alloy comprising aluminum according to claim 21, further comprising a surface layer having a thickness of up to about 50% of the thickness of the coating and being metallurgically bonded to the coating. Alloying component. 26. An aluminum or aluminum alloy surface layer is deposited on the coating by magnetron sputtering to a thickness of up to about 20% of the thickness of the coating and protected in an oxidizing atmosphere at a temperature of about 1000 ° C. or higher. Oxidized over a period of time effective to produce an alumina scale on it,
A surface alloying component as claimed in claim 25. 27. A nitride or carbide deposited on a substrate and between the substrate and the coating, which is metallurgically bonded to the substrate and the coating, and which is continuous with the coating and the portion of the substrate surface. 21. The surface alloying component as claimed in claim 20, further comprising an intermediate layer effective to minimize or avoid layer formation. 28. The thickness of the intermediate layer is about 20 to 100 μm and is about 3 by weight.
5 to 45% aluminum, about 5 to 15% titanium or chromium, and about 45
28. The surface alloying component as claimed in claim 27, comprising-55% silicon. 29. On the substrate, further comprising an intermediate layer deposited between the substrate and the MCrAlX coating and having a thickness of about 20-100 μm, said intermediate layer comprising about 50% chromium and about 50% by weight. 50% nickel or about 20% titanium, 20
21. A surface alloying component as claimed in claim 20 comprising% aluminum and a balance amount of silicon. 30. The surface alloying component as claimed in claim 28, wherein the thickness of the intermediate layer before heat treatment is about 20-60 μm. 31. After heat treatment, the intermediate layer has a diffusion barrier between the stainless steel substrate and the coating containing one or more of silicon and titanium or aluminum and an intermetallic compound of the base alloying element. A surface alloying component as claimed in claim 28. 32. After heat treatment, stainless steel and about 6-10% by weight silicon, 0-5% by weight aluminum, 0-4% by weight titanium and about 25-50% by weight chromium, balance iron. 31. A surface alloying component as claimed in claim 30, wherein the intermediate layer has a diffusion barrier between and and a coating comprising nickel and any base alloying elements. 33. An anti-caulking, corrosion resistant reactor tube or fitting for use in a high temperature environment, comprising a drawn tube or fitting made from a high temperature stainless steel alloy and an inner surface of the drawn tube or fitting. Included is a continuous coating deposited, the coating comprising MCrAlX alloys, where M is Ni, Co, Fe or a mixture thereof, X is yttrium, hafnium, zirconium, lanthanum, scandium or combinations thereof. Yes, containing about 10-25% chromium by weight, about 5-20% aluminum and up to about 3% yttrium, hafnium, zirconium, lanthanum or scandium, a balance amount of M, and
An anti-caulking, corrosion resistant reactor tube or fitting that is metallurgically bonded to the inner surface of a drawn tube or fitting and heat treated at a temperature effective to impart a multiphase microstructure to the MCrAlX alloy coating. 34. Aluminum, an aluminum alloy containing up to 50% by weight of silicon, or up to 60% by weight of silicon and up to 30% by weight of titanium and / or chromium and a balance amount of at least about 20% by weight. %
34. The method of claim 33, further comprising a surface layer comprising an aluminum alloy including aluminum of up to about 50% of the thickness of the coating metallurgically bonded to the coating and having an alumina scale thereon. Anti-caulking, anti-corrosion reactor tube or fittings fitted. 35. About 35-45% aluminum, about 5-15, by weight.
% Chromium or titanium, and about 45-55% silicon, deposited on the inner surface of the draw tube or fitting as an intermediate layer between the stainless steel substrate and the coating, to the inner surface of the draw tube and the coating. 34. The anti-caulking, corrosion resistant reactor tube or fitting as claimed in claim 33, further comprising a metallurgically bonded intermediate layer. 36. The anti-caulking, corrosion resistant reactor tube or fitting as claimed in claim 35, wherein the thickness of the intermediate layer prior to heat treatment is about 20-100 μm. 37. The intermediate layer has a diffusion barrier between a stainless steel substrate and an enriched reservoir containing silicon and one or more of titanium or aluminum and an intermetallic compound of the elements of the base alloy. An anti-caulking, corrosion resistant reactor tube or fitting as claimed in claim 36. 38. Stainless steel with about 6-10% by weight silicon, 0-5% by weight aluminum, 0-4% by weight titanium and about 25-50% by weight chromium.
37. An anti-caulking, corrosion resistant reactor tube as claimed in claim 36, wherein the intermediate layer has a diffusion barrier between a balance amount of a coating containing iron and nickel and any base alloying element. fitting. 39. An anti-caulking, corrosion resistant reactor tube or fitting made by the method of claim 4. 40. An anti-caulking, corrosion resistant reactor tube or fitting made by the method of claim 7. 41. An anti-caulking, corrosion resistant, reactor tube or fitting made by the method of claim 16. 42. A furnace for ethylene production having a plurality of reactor tubes each comprising a drawn tube made from a high temperature stainless steel alloy and a continuous coating deposited on the inner surface of the drawn tube. , MCrAlX
Alloys, where M is Ni, Co, Fe or mixtures thereof, X is yttrium, hafnium, zirconium, lanthanum, scandium or combinations thereof, and about 10-25% chromium by weight, About 5 to 20% aluminum and about 0.25 to 1.5% yttrium, hafnium, zirconium, lanthanum or scandium or a combination thereof, a balance amount of M, including a MCrAlX alloy topcoat on the drawn tube. A furnace, metallurgically bonded to the inner surface and heat treated at a temperature effective to impart a multiphase microstructure to the MCrAlX alloy topcoat. 43. Each reactor tube further comprises aluminum, 50
From an aluminum alloy containing up to 60% by weight of silicon, or up to 60% by weight of silicon and up to 30% by weight of either or both titanium and chromium and a balance amount of at least about 20% by weight of aluminum. 43. The furnace as claimed in claim 42, further comprising a surface layer having a thickness of up to 50% of the coating thickness, metallurgically bonded to the MCrAlX coating, and having an alumina scale thereon. 44. Each reactor tube has a thickness of about 20-100 μm.
And, by weight, about 35-45% aluminum, about 5-15% titanium, and about 45-55% silicon on the inner surface of the stretch tube between the stainless steel substrate and the coating. 44. The furnace as claimed in claim 43, further comprising an intermediate layer deposited and metallurgically bonded to the inner surface of the stretch tube and the coating. 45. A method of applying a protective inert coating to high temperature stainless steel, comprising metallurgically combining successive coatings of MCrAlX alloy, wherein M is nickel, cobalt or Iron or a mixture thereof, wherein X is yttrium, hafnium, zirconium, lanthanum, scandium or a combination thereof, wherein about 0-40% by weight of chromium, about 3-about.
Comprising 30% by weight of aluminum and up to about 5% by weight of X, a balance amount of M,
This is performed on a high temperature stainless steel substrate by a plasma transfer type arc coating deposition method. 46. The MCrAlX alloy is about 10-25% by weight chromium,
46. The method as claimed in claim 45, comprising 4-20 wt% aluminum and up to 3 wt% X. 47. The method as claimed in claim 45, wherein the coating is deposited on the substrate to a thickness of about 20 μm to 6000 μm. 48. A coating is deposited to a thickness of about 50-2000 μm,
48. The method as claimed in claim 47, wherein X is present in an amount of 0.25 to 1.5% by weight. 49. The coating is deposited to a thickness of about 80-500 μm,
The method as claimed in claim 47. 50. MCrAlX is FeCrAlY, 0 to 25% by weight
Chromium, about 3-40% by weight aluminum, up to about 3% by weight yttrium,
46. The method as claimed in claim 45, and including a balance amount of substantially iron. 51. MCrAlX is NiCrAlY, and by weight, about 12-25% chromium, about 4-15% aluminum, and about 0.5-1.5.
49. The method as claimed in claim 48 comprising% yttrium and a balance amount of nickel. 52. Aluminum, an aluminum alloy containing up to 50% by weight of silicon, or up to 60% by weight of silicon and up to 30% by weight of chromium and / or titanium and a balance amount of at least about 20% by weight. %
A surface layer of an aluminum alloy containing aluminum is deposited, the coating having a thickness of up to about 50% of the coating thickness, the coating having aluminum carried thereon and the substrate are heat treated to coat the aluminum. 48. The method as claimed in claim 47, further comprising diffusing therein. 53. The method as claimed in claim 52, wherein the thickness of the layer of aluminum or aluminum alloy deposited on the coating is up to about 20% of the thickness of the coating. 54. A surface alloying component comprising a stainless steel base alloy substrate and a continuous coating having a MCrAlX alloy deposited thereon by plasma transfer arc deposition, wherein M is nickel, cobalt, Iron or a mixture thereof, X is yttrium, hafnium, zirconium, lanthanum, scandium or a combination thereof, and on a weight basis, about 0-40% chromium, about 3-30% aluminum and about 5%. Up to yttrium, hafnium,
A surface alloying component comprising zirconium, lanthanum or a combination thereof, a balance amount of M, wherein the MCrAlX alloy coating has a thickness of about 20-6000 μm and is metallurgically bonded to a stainless steel substrate. 55. MCrAlX alloy is about 4-20 wt% aluminum, 1
55. A surface alloying component comprising a stainless steel substrate as claimed in claim 54 and a MCrAlX alloy comprising 0 to 25 wt% chromium and up to 3 wt% X. 56. X is present in an amount of 0.25 to 1.5% by weight.
Surface alloying components claimed in. 57. MCrAlX is NiCrAlY, based on weight, about 12-25% chromium, about 4-15% aluminum, about 0.5-1.5% by weight.
57. The surface alloying component as claimed in claim 56 comprising yttrium of claim 1, and a balance amount of substantially nickel. 58. The surface alloying component as claimed in claim 55, wherein the thickness of the coating is about 80-500 μm. 59. The aluminum surface layer having a thickness of up to about 50% of the thickness of the coating and being metallurgically bonded to the coating.
Surface alloying components claimed in. 60. The thickness of the aluminum surface layer is about 20 times the thickness of the coating.
60. The surface alloying component as claimed in claim 59, having a protective alumina scale thereon. 61. MCrAlX is FeCrAlY and comprises, by weight, about 0-25% chromium, about 3-40% aluminum, up to about 3% yttrium, and a balance amount of substantially iron. 55. A surface alloying component as claimed in claim 54. 62. An anti-caulking, corrosion resistant reactor tube for use in a high temperature environment, drawn tube made from high temperature stainless steel and metallurgically bonded onto the inner surface of the drawn tube. It includes a continuous coating, the coating including MCrAlX alloy, where M is Ni, Co.
, Fe or a mixture thereof, X is yttrium, hafnium, zirconium,
Lanthanum, scandium or a combination thereof, about 10-25 by weight
% Chromium, about 4-20% aluminum and up to about 3% yttrium, hafnium, zirconium, lanthanum or scandium or combinations thereof, which are plasma-transferred by arc coating deposition to the inside of the drawn tube. Applied to the surface, where the thickness of the MCrAlX coating is about 20 ~
6000 μm, metallurgically bonded to stainless steel substrate, anti-caulking, corrosion resistant reactor tube. 63. An anti-caulking, corrosion resistant reactor tube for use in a high temperature environment, drawn tube made from high temperature stainless steel and metallurgically bonded onto the inner surface of the drawn tube. Including a continuous coating, the coating comprising a MCrAlX alloy, where M is iron and y
Is yttrium and includes, on a weight basis, about 0 to 25% chromium, about 3 to 40% aluminum and up to about 3% yttrium, which is drawn by a plasma transfer arc coating deposition process into a drawn tube. An anti-caulking, corrosion resistant reactor tube applied to the inner surface, wherein the MCrAlX coating has a thickness of about 20-6000 μm and is metallurgically bonded to a stainless steel substrate. 64. The anti-claim as claimed in claim 57 further comprising an aluminum surface layer metallurgically bonded to the coating having a thickness of up to 20% of the thickness of the coating and having an alumina scale thereon. Caulking and corrosion resistant reactor tube. 65. An anti-caulking, corrosion resistant reactor tube made by the method of claim 48. 66. An anti-caulking, corrosion resistant reactor tube made by the method of claim 51. 67. An anti-caulking, corrosion resistant reactor tube made by the method of claim 53. 68. A furnace for ethylene production having a plurality of reactor tubes each comprising a drawn tube made of high temperature stainless steel alloy and a continuous coating of MCrAlX alloy, wherein M is Ni, Co, Fe or mixtures thereof, X is yttrium, hafnium, zirconium, lanthanum, scandium or a combination thereof, about 10-40% chromium by weight,
Stretched tube containing about 3-30% aluminum and up to 5% yttrium, hafnium, zirconium and / or lanthanum, balance M, deposited by plasma transfer arc deposition to a thickness of about 20-6000 μm. Furnace, metallurgically bonded to the inner surface of the furnace. 69. Each reactor tube comprises aluminum, 50% by weight
Aluminum alloy containing up to 60% by weight of silicon, or up to 60% by weight of silicon and up to 30% by weight of either or both titanium and chromium and a balance amount of at least about 20% by weight of aluminum. 69. The furnace as claimed in claim 68, further comprising a surface layer having a thickness of about 50% of the thickness of the coating, metallurgically bonded to the coating, and having an alumina scale thereon. 70. The MCrAlX is NiCrAlY, and by weight, about 10-25% chromium, about 4-20% aluminum, and about 0.5-1.5.
69. The furnace as claimed in claim 68, comprising% yttrium and a balance amount of nickel. 71. MCrAlX further comprising up to about 40% by weight silicon and up to about 10% by weight element T selected from the group consisting of tantalum, titanium, platinum, palladium, rhenium, molybdenum, tungsten, niobium or combinations thereof. Including a coating and a substrate, at a temperature of ablation heat treatment, a multiphase microstructure is obtained,
The method as claimed in claim 1, wherein the coating is metallurgically bonded to the substrate by heat treating for a time effective for the coating to be metallurgically bonded to the substrate. 72. High temperature stainless steel substrate tube and MCrAlXSi
A surface alloying component comprising a coating of a T alloy, wherein M is nickel, cobalt, iron or a mixture thereof, X is yttrium, hafnium, zirconium, lanthanum, scandium or a mixture thereof, and T is Tantalum, titanium, platinum, palladium, rhenium, molybdenum, tungsten, niobium or combinations thereof, wherein about 0-40 wt% chromium, about 1-30 wt% aluminum, up to about 5 wt% X, about Silicon up to 40% by weight and about 10
Surface alloying component containing up to wt% T, balanced M. 73. The MCrAlXSiT alloy comprises about 10-25 wt% chromium, 5-20 wt% aluminum, 3 wt% X, 15 wt% silicon and 10 wt% T. A surface alloying component as claimed in claim 72. 74. X is present in the range of 0.25 to 1.5% by weight.
The surface alloying component claimed in 3. 75. Silicon is present in the range of about 3-15% by weight.
Surface alloying components claimed in. 76. T is present in the range of 0.1 to 5.0% by weight.
Surface alloying components claimed in. 77. T is present in the range of 0.5-3.0% by weight.
Surface alloying components claimed in. 78. The surface alloying component as claimed in claim 72, wherein the thickness of the coating is from 20 μm to 6000 μm. 79. The surface alloying component as claimed in claim 72, wherein the coating has a thickness of 50 μm to 2000 μm. 80. The surface alloying component as claimed in claim 72, wherein the coating has a thickness of 80 μm to 500 μm. 81. The MCrAlXSiT alloy is NiCrAlXSi, comprising about 12-25% by weight chromium, about 4-15% aluminum, about 0.5-1.5% by weight X, up to about 15% by weight silicon and 73. A surface alloying component as claimed in claim 72 comprising a balance amount of nickel. 82. MCrAlXSiT is NiCrAlXTi;
~ 25 wt% chromium, about 4-15% aluminum, about 0.5-1.5 wt%
Yttrium, containing up to about 5% by weight titanium and a balance amount of nickel,
A surface alloying component as claimed in claim 73. 83. MCrAlXSiT is NiCrAlYTa, wherein
~ 25 wt% chromium, about 4-15% aluminum, about 0.5-1.5 wt%
74. A surface alloying component as claimed in claim 73 comprising yttrium of about 0.5-5% by weight tantalum and a balance amount of nickel. 84. MCrAlXSiT is NiCrAlYPt, wherein
~ 25 wt% chromium, about 4-15% aluminum, about 0.5-1.5 wt%
74. A surface alloying component as claimed in claim 73 comprising yttrium of about 0.5-5% by weight platinum and a balance amount of nickel. 85. MCrAlXSiT is NiCrAlYPd, wherein
~ 25 wt% chromium, about 4-15% aluminum, about 0.5-1.5 wt%
74. The surface alloying component as claimed in claim 73, comprising yttrium of about 0.5-5% by weight palladium and a balance amount of nickel. 86. The surface alloying component as claimed in claim 73, further comprising a surface layer up to about 50% of the thickness of the MCrAlXSiT layer. 87. The aluminum alloy comprises up to about 15% by weight silicon, and M
85. A surface alloying component as claimed in claim 84 having a thickness of up to 20% of the CrAlXSiT coating. 88. An anti-caulking, corrosion resistant reactor tube for use in a high temperature environment, drawn tube made of high temperature stainless steel and metallurgically bonded on the inside surface of the drawn tube. Includes a continuous coating, the coating comprising a MCrAlXSiT coating, where M is nickel, cobalt, iron or a mixture thereof, X is yttrium,
Hafnium, zirconium, lanthanum, scandium or combinations thereof, T is tantalum, titanium, platinum, palladium, rhenium, molybdenum, tungsten, niobium or combinations thereof, about 10-25% chromium by weight. , About 4-20% aluminum, up to about 3% by weight X, up to about 15% by weight silicon and up to about 5% by weight T, a balance amount of M, physical vapor deposition, plasma spray or plasma transfer arc. Precipitate by surfacing, where M
An anti-caulking, corrosion resistant reactor tube, wherein the thickness of the CrAlXSiT coating is about 20 μm to 6000 μm. 89. A method of applying a protective inert coating to carbon steel and stainless steel, comprising depositing a continuous coating of MCrAlXSi alloy on a steel substrate and metallurgically bonding it. , Where M is nickel,
Cobalt or iron or mixtures thereof, X is yttrium, hafnium, zirconium, lanthanum, scandium or a combination thereof, wherein about 0-40% by weight chromium, about 3-40% by weight aluminum, about 0- 35% by weight
Silicon and X up to about 5% by weight, at least 40% by weight of the balance of M
Including the method. 90. The method as claimed in claim 89, wherein the coating is deposited by physical vapor deposition, thermal spraying, plasma transfer arc, build-up welding, isostatic pressing, and slurry coating. 91. The coating comprises at least two powders of components of MCrAlXSi, partially prealloyed and interblended and deposited on a substrate,
This is reacted in vacuum or in an oxygen-free atmosphere at temperatures above 500 ° C. and up to about 1200 ° C., reactive sintering is initiated, and the coating is metallurgically as a continuous impermeable coating on a substrate. 90. The method as claimed in claim 89, wherein the heating is for a time effective to bond. 92. The coating is deposited to a thickness of about 50-6000 μm, and M
CrAlXSi coating basically contains about 0-20% by weight chromium, about 4-2
0 wt% aluminum, about 5-20 wt% silicon, and about 0.25-1.
92. The method as claimed in claim 91, comprising 5% by weight yttrium and at least 40% by weight nickel in balance. 93. The substrate is a high chromium stainless steel comprising 18-38% by weight chromium, 18-48% by weight nickel, a balance amount of iron and alloying additives, the coating being about 120-500 μm. 93. The method as claimed in claim 92, wherein the deposition is at a thickness of. 94. The method as claimed in claim 93, wherein the coating is deposited to a thickness of about 150-350 μm. 95. The coating is aluminized by depositing an aluminum layer on the MCrAlXSi coating to a thickness of up to about 50% of the coating, the aluminum layer being at least 10 at an ablation heat treatment temperature in the range of about 1000-1160.degree. 95. The method as claimed in claim 94, wherein the heat treatment is carried out for a period of time sufficient to establish the multiphase structure. 96. The method as claimed in claim 95, wherein the aluminum layer is deposited using magnetron sputtering physical vapor deposition at a temperature in the range of about 200-500 ° C. and a thickness of about 20% of the MCrAlXSi coating. 97. The substrate, MCrAlYSi coating and aluminum layer are subsequently heated in an oxygen containing atmosphere at a temperature in the range of 1000-1160 ° C. for a time effective to form an α-alumina layer thereon. The method as claimed in claim 91. 98. Chromium, aluminium, and silicon are milled to produce Cr prior to blending with nickel, NiCr or NiAl powder or combinations thereof.
The method as claimed in claim 91, wherein the method is AlSi powder. 99. A surface alloying component produced by the method of claim 89. 100. A surface alloying component produced by the method of claim 92.