Nickel-based alloy and preparation method thereof, and fuel cell interconnection plate and preparation method thereof

Abstract

The invention provides a nickel-based alloy and a preparation method thereof, and a fuel cell interconnection plate and a preparation method thereof, and belongs to the field of alloys. The nickel-based alloy comprises the following chemical components: 5%-9.5% of Cr, 1.0%-2.2% of Co, 0.005%-0.2% of Ce, 3.1%-4.0% of Cu, 12%-17.5% of Mo, Clt and the balance of Ni and inevitable impurities. 0.05%, T.O < = 0.002%, and Ni. The chemical components of the nickel-based alloy are reasonably designed, a high-nickel and low-Cr component system is designed, the excellent effect of inhibiting Cr volatilization is achieved while the excellent oxidation resistance is achieved, meanwhile, Ce and Sr are reasonably controlled, the diffusion rate of Sr in an oxidation film is promoted through Ce, and therefore (Ni, Sr and Cu) 3O4 is formed on the outer layer of a Cr2O3 oxidation film, and diffusion of Cr is inhibited. Therefore, the volatilization of Cr in the nickel-based alloy is inhibited.

Description

Technical Field

[0001] The present application relates to the field of alloy technology, and in particular to a nickel-based alloy and a preparation method thereof, and a fuel cell interconnection plate and a preparation method thereof. Background Art

[0002] High-temperature solid oxide fuel cells (800°C) are highly efficient energy conversion devices that convert the chemical energy of fuel into electrical energy without chemical reactions. They can directly use carbon-containing gases such as methane, natural gas and water gas as fuel. In recent years, improvements in material manufacturing processes and design technologies have enabled the operating temperature of SOFCs to be reduced from 1000°C to a medium temperature range of 600°C to 800°C, which also makes it possible to use metal connector materials as connector materials. Metal connectors can meet basic requirements such as electrical conductivity, thermal expansion coefficient, thermal conductivity, and oxidation resistance at operating temperatures.

[0003] The thermal expansion coefficient of each component of the solid oxide fuel cell is 10.5×10 -6 / K~12.5×10 -6 / K, so the thermal expansion coefficient TEC of the metal connector material is required to be close to this to avoid excessive thermal stress that causes rapid degradation of the battery stack performance. Generally, the TEC of austenitic stainless steel and nickel-based alloys is relatively high, generally 16×10 -6 / K~19×10 -6 / K. So far, due to the restriction of thermal expansion coefficient at high temperature, the expansion coefficient of solid electrolyte is 9×10 -6 / K~11×10 -6 / K, the current common practice is to use iron-based alloys. The more delicate ferritic stainless steel connectors include Crofer22APU, SUS430, X10CrAl18 and ZMG232. The more representative ferritic Fe-Cr alloys are ZMG232 developed by Hitachi Metals and Crofer22 APU alloy announced by ThyssenKrupp VDM in 2003. After optimization, ZMG232L and Crofer22H were further developed. Although the above alloys have excellent performance, there are still bottlenecks in commercial use. Although Fe-Cr-based alloys have suitable thermal expansion coefficients and oxidation resistance, due to excessive Cr content, the alloy forms volatile gaseous substances in an oxidizing environment. These volatile substances will be deposited on the cathode surface, seriously damaging the electrochemical performance of SOFC, and currently cannot meet the requirements of long-term operation of SOFC battery stacks. Therefore, a nickel-based alloy with low Cr volatilization is urgently needed. Summary of the invention

[0004] The present application provides a nickel-based alloy and a preparation method thereof, a fuel cell interconnection plate and a preparation method thereof, in order to solve the following technical problem: how to suppress the volatilization of Cr in the nickel-based alloy.

[0005] In a first aspect, the present application provides a nickel-based alloy, which includes the following chemical components, measured by mass fraction: Cr: 5% to 9.5%, Co: 1.0% to 2.2%, Ce: 0.005% to 0.2%, Cu: 3.1% to 4.0%, Mo: 12% to 17.5%, C<0.05%, TO≤0.002% and Ni.

[0006] Optionally, the chemical composition satisfies the following relationship:

[0007] 0.005≤[Ce] / [Co]≤0.1

[0008] Wherein, [Ce] represents the mass fraction of Ce, and [Co] represents the mass fraction of Co.

[0009] Optionally, the chemical composition satisfies the following relationship:

[0010] 4.5%≤0.8[Cr]+0.3[Co]+0.15[Cu]≤8%

[0011] Wherein, [Cr] represents the mass fraction of Cr, [Co] represents the mass fraction of Co, and [Cu] represents the mass fraction of Cu. Optionally, the chemical composition satisfies the following relationship:

[0012] 1.5≤(2.2[Cr]+2.4[Co]+3.2[Cu]) / [Mo]≤3

[0013] In the formula, [Cr] represents the mass fraction of Cr, [Co] represents the mass fraction of Co, [Cu] represents the mass fraction of Cu, and [Mo] represents the mass fraction of Mo.

[0014] Optionally, the cast structure of the nickel-based alloy includes, by volume fraction, γ phase ≧70%, BCC phase ≤10%, μ phase ≤3%, and б phase ≤2%.

[0015] In a second aspect, the present application provides a method for preparing the nickel-based alloy according to any one embodiment of the first aspect, the method comprising the following steps:

[0016] The nickel-based steel liquid is subjected to vacuum refining, and when the TO of the nickel-based steel liquid is less than or equal to 0.002%, an alloy containing Cr, Ce, Mo, Co and Cu is added to the nickel-based steel liquid to obtain an alloyed steel liquid;

[0017] The alloyed nickel-based steel liquid is poured to obtain a nickel-based alloy containing the chemical composition.

[0018] In a third aspect, the present application provides a fuel cell interconnection plate, wherein the fuel cell interconnection plate is made of the nickel-based alloy described in any one of the embodiments in the first aspect.

[0019] Optionally, the fuel cell interconnect plate includes at least one of the following properties:

[0020] ASR≤0.004Ω·cm at 900℃ for 10000h 2 ;

[0021] The thermal expansion coefficient at 900°C is 10×10 -6 / K~12×10 -6 / K;

[0022] The total thickness of the oxide film after oxidation at 900℃ for 30,000 hours is less than 10μm;

[0023] 400mA / cm at 900℃ 2 The cathode deposited Cr content of the current polarization for 4000h is ≤0.004mg / cm 2 ;

[0024] 900℃ tensile strength ≥360MPa, 900℃ yield strength ≥320MPa.

[0025] In a fourth aspect, the present application provides a method for preparing the fuel cell interconnection plate according to the embodiment of the third aspect, the method comprising:

[0026] The nickel-based alloy described in any one of the embodiments of the first aspect is rolled, stamped and solution treated to obtain a fuel cell interconnection plate.

[0027] Optionally, the solution treatment includes the following parameters: solution treatment temperature is 1050°C to 1080°C, holding time is 1h to 3h, hydrogen injection volume is ≥ 20m 3 / h.

[0028] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0029] The present application provides a nickel-based alloy, which includes the following chemical components by mass fraction: Cr: 5% to 9.5%, Co: 1.0% to 2.2%, Ce: 0.005% to 0.2%, Cu: 3.1% to 4.0%, Mo: 12% to 17.5%, C<0.05%, TO≤0.002% and Ni. The chemical composition of the nickel-based alloy is reasonably designed, and a high-nickel and low-Cr component system is designed to achieve excellent antioxidant properties while having an excellent effect of inhibiting Cr volatilization. Ce and Sr are reasonably controlled, and Ce is used to promote the diffusion rate of Sr in the oxide film, thereby forming (Ni, Sr, Cu)3O4 in the outer layer of the Cr2O3 oxide film to inhibit the diffusion of Cr. And the conductivity of (Ni, Sr, Cu)3O4 is 5 to 7 times that of Cr2O3, which greatly enhances the conductivity of the oxide film. Adding Mo significantly reduces the thermal expansion coefficient of nickel-based alloys, and by matching and coordinating with Cr, an element that increases the thermal expansion coefficient of the alloy, the thermal expansion coefficient of solid oxide fuel cells is met. At the same time, through the composition ratio of Mo, Cu, Sr, and Cr alloy elements, under medium-temperature oxidizing atmosphere conditions, due to the external diffusion of Cr, Ni, Sr, and Cu, holes are formed between the matrix and the oxide film, which promotes the diffusion of Mo into the holes and reaches the critical formation conditions of Ni3Mo, forming a conductive barrier between the matrix and the oxide film that inhibits Cr volatilization, preventing corrosion from extending to the matrix and enhancing the conductivity between the matrix and the oxide film. Thus, the volatilization of Cr in the nickel-based alloy is inhibited. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0032] Figure 1 A schematic diagram of a process for preparing a nickel-based alloy provided in an embodiment of the present application;

[0033] Figure 2 The as-cast structure diagram of the nickel-based alloy provided in Example 1 of the present application;

[0034] Figure 3 This is the metallographic structure diagram of the nickel-based alloy provided in Example 1 of the present application. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0036] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0037] In addition, in the description of the specification of the present application, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second", etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" means one or more, and "plurality" means two or more. "At least one", "the following at least one item (items)" or similar expressions refer to any combination of these items, including any combination of single items (items) or plural items (items). For example, "at least one of a, b, or c", or "at least one of a, b, and c", can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple. "Parts" such as parts by weight and parts by mass indicate the proportional relationship between the components. In the proportional relationship involved in this article, the parameters that need to be described by proportion should be understood as the first term of the proportional formula in the order of description, and the proportional numbers should be understood as the second term of the proportional formula. For example, the mass ratio of substance A, substance B, and substance C is 1:2:3, then substance A, substance B, and substance C should correspond one-to-one with the proportional numbers in the proportional formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0038] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0039] The present application provides a nickel-based alloy, which includes the following chemical components, measured by mass fraction: Cr: 5% to 9.5%, Co: 1.0% to 2.2%, Ce: 0.005% to 0.2%, Cu: 3.1% to 4.0%, Mo: 12% to 17.5%, C<0.05%, TO≤0.002% and Ni.

[0040] The specific functions of each chemical component of nickel-based alloy are as follows:

[0041] Cr: A basic element to ensure the oxidation resistance and thermal expansion performance of stainless steel. If the content is less than 5%, the oxidation resistance of the present invention cannot be achieved. Due to the solid solution effect of Cr, if it is higher than 9.5%, it will cause excessive lattice distortion, thereby causing excessive scattering of conductive electrons and reducing the conductivity of stainless steel. Exemplarily, the Cr content can be 5%, 5.5%, 6%, 6.5%, 7%, 8%, 9%, 9.5%, etc.

[0042] Mo: On the one hand, the thermal expansion coefficient of Ni-based alloy is generally above 14, and the addition of Mo element has the effect of significantly reducing the thermal expansion coefficient of Ni-based alloy; on the other hand, under the conditions of 600-900℃, 20% O2, and 80% H2O, Mo in the matrix can diffuse to fill the vacancies of Cr, exist between the matrix and the oxide film, prevent corrosion from extending to the matrix, and enhance the conductivity between the matrix and the oxide film. With the synergistic effects of the two aspects, the optimal Mo content is 12% to 17.5%. Exemplarily, the Mo content can be 12%, 12.5%, 13%, 14%, 15%, 16%, 17%, 17.5%, etc.

[0043] Co: forms (Ni, Co, Cr) 3 O 4 on the outer layer of the Cr 2 O 3 oxide film, inhibiting the diffusion of Cr, and the conductivity of (Ni, Co, Cr) 3 O 4 is 2 to 5 times that of Cr 2 O 3, greatly enhancing the conductivity of the oxide film. Exemplarily, the content of Co can be 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, etc.

[0044] Ce: Ce is used to promote the diffusion rate of Co in the oxide film. For example, the content of Ce may be 0.005%, 0.01%, 0.03%, 0.05%, 0.1%, 0.12%, 0.15%, 0.2%, etc.

[0045] Cu: Improves the oxide film structure, inhibits Cr volatilization, and inhibits the outward diffusion of Cr through the reasonable matching of alloy element components and diffusion rate, and the inner wall (Cu, Cr)3O4 of (Ni, Co, Cr)3O4 under medium temperature oxidizing atmosphere. The amount of Cu added should be controlled at 3.1% to 4.0%. Exemplarily, the Cu content can be 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, etc.

[0046] It can be seen that the present application designs a high-nickel, low-Cr component system to achieve excellent antioxidant properties while having an excellent effect of inhibiting Cr volatilization. Reasonably control Ce and Sr, and use Ce to promote the diffusion rate of Sr in the oxide film, thereby forming (Ni, Sr, Cu) 3O4 in the outer layer of the Cr2O3 oxide film to inhibit the diffusion of Cr. And the conductivity of (Ni, Sr, Cu) 3O4 is 5 to 7 times that of Cr2O3, which greatly enhances the conductivity of the oxide film. Adding Mo significantly reduces the thermal expansion coefficient of nickel-based alloys, and by matching and synergizing with the element Cr that increases the thermal expansion coefficient of the alloy, the thermal expansion coefficient of solid oxide fuel cells is met. At the same time, through the composition ratio of Mo, Cu, Sr, and Cr alloy elements, under medium-temperature oxidizing atmosphere conditions, due to the external diffusion of Cr, Ni, Sr, and Cu, holes are formed between the substrate and the oxide film, which promotes the diffusion of Mo into the holes and reaches the critical formation condition of Ni3Mo, forming a conductive barrier between the substrate and the oxide film that inhibits Cr volatilization, preventing the extension of corrosion to the substrate and enhancing the conductivity between the substrate and the oxide film.

[0047] It should be noted that TO is the total oxygen content.

[0048] Ni is a matrix element. The specific content / content range of Ni can be obtained through the upper and lower limit formula of the component, that is, the sum of the percentages of the contents of each component in a composition should be equal to 100%, and the content ranges of several components should meet the following conditions: the upper limit value of a component + the lower limit value of other components ≤ 100; the lower limit value of a component + the upper limit value of other components ≥ 100.

[0049] In some embodiments, the chemical composition satisfies the following relationship:

[0050] 0.005≤[Ce] / [Co]≤0.1

[0051] Wherein, [Ce] represents the mass fraction of Ce, and [Co] represents the mass fraction of Co.

[0052] The limit of 0.005≤[Ce] / [Co]≤0.1 ensures that Ce can play its role in promoting the diffusion of Sr, while avoiding the formation of large-sized inclusions due to excessive Ce addition, thereby deteriorating the performance of the alloy. For example, the value of [Ce] / [Co] can be 0.005, 0.01, 0.02, 0.04, 0.05, 0.06, 0.08, 0.09, 0.1, etc.

[0053] In some embodiments, the chemical composition satisfies the following relationship:

[0054] 4.5%≤0.8[Cr]+0.3[Co]+0.15[Cu]≤8%

[0055] In the formula, [Cr] represents the mass fraction of Cr, [Co] represents the mass fraction of Co, and [Cu] represents the mass fraction of Cu.

[0056] The present application rationally designs the relationship between Cr, Cu, and Co to form an oxide layer with a three-layer structure, which are Cr2O3, (Cu, Cr)3O4, and (Ni, Co, Cr)3O4 from the inside to the outside. If 0.8[Cr]+0.3[Co]+0.15[Cu]≤4.5%, then under service conditions, i.e., medium temperature conditions, oxidizing atmosphere and reducing atmosphere conditions, the three types of alloy elements Cr, Cu, and Co cannot diffuse into the oxide layer; if 0.8[Cr]+0.3[Co]+0.15[Cu]≥8%, unfavorable intermetallic compounds are formed in the nickel-based matrix. These intermetallic compounds may inhibit the diffusion of elements such as Cr, Cu, and Co to the oxide layer, thereby also failing to form the desired three-layer structure. Exemplarily, the value of 0.8[Cr]+0.3[Co]+0.15[Cu] can be 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, etc.

[0057] In some embodiments, the chemical composition satisfies the following relationship:

[0058] 1.5≤(2.2[Cr]+2.4[Co]+3.2[Cu]) / [Mo]≤3

[0059] In the formula, [Cr] represents the mass fraction of Cr, [Co] represents the mass fraction of Co, [Cu] represents the mass fraction of Cu, and [Mo] represents the mass fraction of Mo.

[0060] By precisely controlling the mass fraction ratio of Cr, Cu, Co and Mo, an appropriate amount of vacancies is formed in the nickel-based alloy, the diffusion of Mo is promoted, and the Ni3Mo intermetallic compound is formed with Ni, thereby forming a uniform barrier between the matrix and the oxide film. On the one hand, the conductivity of the matrix and the oxide film is enhanced; on the other hand, the diffusion of Cr is further inhibited and the oxidation rate is reduced. If (2.2[Cr]+2.4[Co]+3.2[Cu]) / [Mo]≤1.5, it means that the total content of Cr, Co and Cu is low relative to the content of Mo, resulting in the formation of Ni3Mo that cannot form a continuous film, and thus cannot achieve the effect of enhancing the conductivity of the matrix and the oxide film and further inhibiting the diffusion of Cr. If (2.2[Cr]+2.4[Co]+3.2[Cu]) / [Mo]≥3, it means that the content of Mo is low relative to the total content of Cr, Co and Cu. This will cause Mo to diffuse further outward because there are too many vacancies and Mo does not have enough Ni to form Ni3Mo. Excessive diffusion of Mo will lead to increased volatilization of Cr. For example, the value of (2.2[Cr]+2.4[Co]+3.2[Cu]) / [Mo] can be 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, etc.

[0061] In some embodiments, the cast structure of the nickel-based alloy includes, by volume fraction: γ phase ≧70%, BCC phase ≤10%, μ phase ≤3%, and б phase ≤2%.

[0062] The γ phase is a solid solution phase in nickel-based alloys, which has good toughness and plasticity, and can maintain a certain strength and toughness at high temperatures. High γ phase content helps to improve the oxidation resistance of the alloy, because the γ phase can accommodate more alloying elements and form a stable oxide film, thereby protecting the matrix from further oxidation. For example, the volume fraction of the γ phase can be 70%, 72%, 75%, 78%, 80%, 85%, etc., the volume fraction of the BCC phase can be 4%, 5%, 6%, 7%, 9%, 10%, etc., the volume fraction of the μ phase can be 1%, 1.5%, 2%, 2.5%, 3%, etc., and the volume fraction of the б phase can be 0.5%, 1%, 1.5%, 2%, etc.

[0063] Figure 1 A schematic flow chart of a method for preparing a nickel-based alloy provided in an embodiment of the present application.

[0064] Based on a general inventive concept, see Figure 1 The present application also provides a method for preparing the nickel-based alloy described in any one of the above embodiments, the method comprising the following steps:

[0065] S1, vacuum refining the nickel-based steel liquid, and when the TO of the nickel-based steel liquid is ≤0.002%, adding an alloy containing Cr, Ce, Mo, Co and Cu to the nickel-based steel liquid to obtain an alloyed steel liquid;

[0066] It should be noted that nickel-based molten steel is a special alloy melt with nickel as the main component and other alloy elements added to improve its performance.

[0067] In step S1, when the alloy is added, TO in the nickel-based molten steel is ≤20ppm. At this time, the nickel-based molten steel has been completely deoxidized, which can reduce the risk of alloy oxidation and improve the alloy yield.

[0068] In some embodiments, when the vacuum refining time reaches 0.6T to 0.8T, an alloy containing Cr, Ce, Mo, Co and Cu is added to the nickel-based steel liquid, wherein T is the total vacuum refining time.

[0069] When the vacuum refining time reaches 0.6T to 0.8T, an alloy containing Cr, Ce, Mo, Co and Cu is added before steel is tapped in the later stage of refining. At this time, under normal circumstances, TO in the nickel-based steel liquid is ≤20ppm, which can improve the recovery rate of expensive rare earth elements. If the alloy is added earlier than 0.6T, the recovery rate of the alloy elements will be reduced to a certain extent. If the alloy is added later than 0.8T, it will cause the alloy to be uneven to a certain extent, and the conductivity and oxidation resistance of the product will be uneven.

[0070] S2. pouring the alloyed nickel-based steel liquid to obtain a nickel-based alloy containing the chemical composition.

[0071] The product prepared by the method for preparing the nickel-based alloy is the above-mentioned nickel-based alloy. The chemical composition and microstructure of the nickel-based alloy prepared by the method for preparing the nickel-based alloy can refer to the above-mentioned embodiment. Since the method for preparing the nickel-based alloy adopts part or all of the technical solutions of the nickel-based alloy embodiment, it at least has all the beneficial effects brought by the technical solutions of the nickel-based alloy embodiment, which will not be described one by one here.

[0072] Based on a general inventive concept, the present application provides a fuel cell interconnection plate, wherein the fuel cell interconnection plate is made of the nickel-based alloy described in any one of the above embodiments.

[0073] The fuel cell interconnection plate can form a large amount of intermetallic compounds to improve the conductivity of the interconnection plate during the working stage. At the same time, the interconnection plate has good oxidation resistance and conductivity during the operation of the fuel cell, thereby improving the service life of the fuel cell.

[0074] In some embodiments, the fuel cell interconnect plate comprises at least one of the following properties: ASR≤0.004Ωcm at 900°C oxidation for 10000h 2 , the thermal expansion coefficient at 900°C is 10×10 -6 / K~12×10 -6 / K, the total thickness of the oxide film after oxidation at 900℃ for 30000h is less than 10μm, at 900℃ 400mA / cm 2 The cathode deposited Cr content of the current polarization for 4000h is ≤0.004mg / cm 2 , 900℃ tensile strength ≥360MPa, 900℃ yield strength ≥320MPa.

[0075] ASR represents the resistance per unit area. This application develops a nickel-based low-Cr system and cooperates with the beneficial effects of trace elements Ce, Co, Mo, and Cu to make the product meet the requirements of anti-oxidation performance, low Cr volatilization, conductivity, thermal expansion coefficient, and high-temperature mechanical properties, and meet the working conditions of solid fuel oxide batteries.

[0076] Based on a general inventive concept, the present application provides a method for preparing the fuel cell interconnection plate described in the above embodiment, the method comprising:

[0077] The nickel-based alloy described in any one of the above embodiments is rolled, stamped and solution treated to obtain a fuel cell interconnection plate.

[0078] In some embodiments, the solution treatment includes the following parameters: the solution treatment temperature is 1050°C to 1080°C, the holding time is 1h to 3h, the hydrogen injection volume is ≥ 20m 3 / h.

[0079] In the solution treatment, the solution treatment temperature is limited to 1050℃~1080℃, and the holding time is 1h~3h, so that the elements in the alloy are fully dissolved in the matrix to form a uniform solid solution. This helps to improve the corrosion resistance, strength and toughness of the alloy. During the solution treatment process, hydrogen spraying is also used to prevent the nickel-based alloy from oxidizing during the solution treatment process. Exemplarily, the solution treatment temperature can be 1050℃, 1055℃, 1060℃, 1065℃, 1070℃, 1075℃, 1080℃, etc., the holding time can be 1h, 1.2h, 1.5h, 1.8h, 2h, 2.2h, 2.5h, 2.8h, 3h, etc., and the hydrogen spraying amount can be 20m 3 / h、22m 3 / h、25m 3 / h、28m 3 / h、30m 3 / h, etc.

[0080] The product prepared by the preparation method of the fuel cell interconnection plate is the above-mentioned fuel cell interconnection plate. The chemical composition and microstructure of the fuel cell interconnection plate prepared by the preparation method of the fuel cell interconnection plate can refer to the above-mentioned embodiment. Since the preparation method of the fuel cell interconnection plate adopts part or all of the technical solutions of the fuel cell interconnection plate embodiment, it at least has all the beneficial effects brought by the technical solutions of the fuel cell interconnection plate embodiment, which will not be repeated here one by one.

[0081] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to industry standards. If there is no corresponding industry standard, then the conditions recommended by the manufacturer are followed.

[0082] This embodiment provides a method for preparing a fuel cell interconnection plate, and the specific process is as follows:

[0083] Step 1: Add electrolytic nickel, Cr alloy, C, Co, Mo and Cu into a vacuum induction furnace for vacuum refining. The loading amount of the vacuum induction furnace is 3 tons. The vacuum refining time is 60 minutes and the vacuum refining temperature is 1500° C. to 1650° C. The vacuum refining temperature, the time of adding the alloy containing Cr, Ce, Mo, Co and Cu and the TO at that time are shown in Table 1.

[0084] Step 2: pouring and crystallizing the nickel-based steel liquid in step 1 to obtain a nickel-based alloy ingot, heating the alloy ingot at 1100° C., forging and tempering the alloy ingot multiple times to obtain a flat slab; wherein the chemical composition of the nickel-based alloy ingot is shown in Table 2, and the relationship between the chemical compositions of the nickel-based alloy ingot is shown in Table 3.

[0085] Step 3, hot rolling, annealing, softening, grinding and welding the flat slab to obtain a hot-rolled strip;

[0086] Step 4: performing blanking, cold rolling, intermediate grinding, edge trimming and solution treatment on the hot-rolled strip to obtain a strip.

[0087] The hot rolling temperature is 1100°C. The hot rolling includes: a first hot rolling, a second hot rolling and a third hot rolling. The deformation of the first hot rolling is 40%, the deformation of the second hot rolling is 30%, and the deformation of the third hot rolling is 30%. The final rolling temperature is 910°C. After rolling, the steel is water-cooled to room temperature.

[0088] The cold rolling includes: a first cold rolling, a second cold rolling and a third cold rolling. The deformation amount of the first cold rolling is 30%, the deformation amount of the second cold rolling is 40%, and the deformation amount of the third cold rolling is 50%.

[0089] Step 5: Stamping: Heat treatment to 300°C, spray hydrogen volume 5m 3 / h, keep warm for 20min, and then perform stamping.

[0090] Step 6: Solution treatment of the alloy plate after stamping in step S5: solution treatment temperature 1050℃~1080℃, holding time 1h~3h and hydrogen spraying volume ≥20m 3 / h, and a fuel cell interconnection plate is obtained. The specific parameters of the solution treatment are shown in Table 4.

[0091] Table 1 Vacuum refining temperature and alloy addition time and TO at that time

[0092]

[0093] Table 2 Chemical composition of nickel-based alloy ingots

[0094] serial number Cr / ％ Co / % Mo / % Cu / % Ce / % C / ％ TO / % Example 1 5 1 12 3.1 0.005 0.025 0.0015 Example 2 6 1.5 13 4 0.1 0.020 0.0016 Example 3 7 2 14 3.5 0.15 0.030 0.0014 Example 4 8 2 15 3.2 0.2 0.025 0.0015 Example 5 9 2 17 3.2 0.1 0.030 0.0014 Comparative Example 1 5 2 12 3.1 0.005 0.025 0.0015 Comparative Example 2 4 0.5 10 2 0.005 0.025 0.0015

[0095] Table 3 Relationship between the chemical compositions of nickel-based alloy ingots

[0096] serial number [Ce] / [Co] 0.8[Cr]+0.3[Co]+0.15[Cu] / % (2.2[Cr]+2.4[Co]+3.2[Cu]) / [Mo] Example 1 0.005 4.765 1.96 Example 2 0.067 5.85 2.29 Example 3 0.075 6.725 2.26 Example 4 0.1 7.525 2.26 Example 5 0.05 8.28 2.07 Comparative Example 1 0.0025 5.1 2.2 Comparative Example 2 0.01 3.65 1.65

[0097] Table 4 Specific parameters of solution treatment

[0098] serial number Solution treatment temperature / ℃ Insulation time / h <![CDATA[Hydrogen injection rate / m 3 / h]]> Example 1 1050 1.0 20 Example 2 1055 1.5 25 Example 3 1060 2.0 30 Example 4 1070 2.5 20 Example 5 1080 3.0 25 Comparative Example 1 1060 2.0 30 Comparative Example 2 1060 2.5 25

[0099] The fuel cell interconnect plates prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were oxidized at 600°C to 900°C for 30,000 h in a 20% O2-80% H2O atmosphere, and the oxide film thickness and the resistance per unit area (ASR) were measured respectively; 400 mA / cm at 900°C 2 The current polarization was performed for 4000 h, and the cathode deposited Cr-containing substances were measured. The tensile test was performed at 900 °C, and the results are shown in Table 5.

[0100] Table 5 Performance of fuel cell interconnection plates prepared in Examples 1 to 5 and Comparative Examples 1 to 2

[0101]

[0102] As shown in Table 5, the fuel cell interconnection plates provided in Examples 1 to 5 of the present application have an ASR of ≤0.004 Ωcm when oxidized at 900°C for 10,000 hours. 2 , the thermal expansion coefficient at 900°C is 10×10 -6 / K~12×10 -6 / K, the total thickness of the oxide film after oxidation at 900℃ for 30000h is less than 10μm, at 900℃ 400mA / cm2 The cathode deposited Cr content of the current polarization for 4000h is ≤0.004mg / cm 2 , 900℃ tensile strength ≥360MPa, 900℃ yield strength ≥320MPa. It can be seen that the fuel cell interconnection plate provided in the present application simultaneously meets the requirements of anti-oxidation performance, low Cr volatilization, conductivity, thermal expansion coefficient and high-temperature mechanical properties, and meets the working conditions of solid fuel oxide cells.

[0103] In Comparative Example 1, [Ce] / [Co]=0.0025, which does not meet the requirement of 0.005≤[Ce] / [Co]≤0.1. The total thickness of the oxide film of the provided fuel cell interconnect plate after oxidation at 900°C for 30,000 hours is greater than 10 μm, the oxide film thickness is thick, and the oxidation resistance is poor; the ASR after oxidation at 900°C for 10,000 hours is greater than 0.004 Ωcm 2 , high resistance per unit area, poor conductivity; 400mA / cm at 900℃ 2 The cathode deposited Cr content after current polarization for 4000h is > 0.004mg / cm 2 , Cr volatilizes more.

[0104] In Comparative Example 2, [Ce] / [Co]=0.01, 0.8[Cr]+0.3[Co]+0.15[Cu]=3.65, which does not meet the requirements of 0.005≤[Ce] / [Co]≤0.1, 4.5%≤0.8[Cr]+0.3[Co]+0.15[Cu]≤8%. The total thickness of the oxide film of the provided fuel cell interconnect plate after oxidation at 900°C for 30,000 hours is greater than 10 μm, the oxide film is thick, and the oxidation resistance is poor; the ASR after oxidation at 900°C for 10,000 hours is greater than 0.004 Ωcm 2 , high resistance per unit area, poor conductivity; 400mA / cm at 900℃ 2 The cathode deposited Cr content after current polarization for 4000h is > 0.004mg / cm 2 , Cr volatilizes more.

[0105] Figure 2 The as-cast structure diagram of the nickel-based alloy provided in Example 1 of the present application; Figure 3 This is the metallographic structure diagram of the nickel-based alloy provided in Example 1 of the present application. Figure 2 and Figure 3 It can be seen that the cast structure of the nickel-based alloy of Example 1 includes: γ phase ≧ 70%, BCC phase ≤ 10%, μ phase ≤ 3%, and б phase ≤ 2%.

[0106] In addition, one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0107] In the embodiments of the present application, the fuel cell interconnection plate provided satisfies the requirements of anti-oxidation performance, low Cr volatilization, electrical conductivity, thermal expansion coefficient and high-temperature mechanical properties, and meets the operating requirements of the solid fuel oxide cell.

[0108] In the embodiments of the present application, by designing reasonable alloy element addition and ratio and optimizing process preparation technology, the problem of existing alloys having both oxidation resistance, electrical conductivity and thermal expansion properties at medium and high temperature operating temperatures of 600°C to 900°C is solved.

[0109] In the embodiment of the present application, the fuel cell interconnection plate provided has an ASR of ≤0.004Ωcm after oxidation at 900°C for 10000h. 2 , the thermal expansion coefficient at 900°C is 10×10 -6 / K~12×10 -6 / K, the total thickness of the oxide film after oxidation at 900℃ for 30000h is less than 10μm, at 900℃ 400mA / cm 2 The cathode deposited Cr content of the current polarization for 4000h is ≤0.004mg / cm 2 , 900℃ tensile strength ≥360MPa, 900℃ yield strength ≥320MPa.

[0110] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A nickel-based alloy, comprising the following chemical components by mass fraction: Cr: 5% to 9.5%, Co: 1.0% to 2.2%, Ce: 0.005% to 0.2%, Cu: 3.1% to 4.0%, Mo: 12% to 17.5%, C<0.05%, TO≤0.002% and Ni.

2. The nickel-based alloy according to claim 1, characterized in that The chemical composition satisfies the following relationship: 0.005≤[Ce] / [Co]≤0.1 Wherein, [Ce] represents the mass fraction of Ce, and [Co] represents the mass fraction of Co.

3. The nickel-based alloy according to claim 1, characterized in that The chemical composition satisfies the following relationship: 4.5%≤0.8[Cr]+0.3[Co]+0.15[Cu]≤8% In the formula, [Cr] represents the mass fraction of Cr, [Co] represents the mass fraction of Co, and [Cu] represents the mass fraction of Cu.

4. The nickel-based alloy according to claim 1, characterized in that The chemical composition satisfies the following relationship: 1.5≤(2.2[Cr]+2.4[Co]+3.2[Cu]) / [Mo]≤3 In the formula, [Cr] represents the mass fraction of Cr, [Co] represents the mass fraction of Co, [Cu] represents the mass fraction of Cu, and [Mo] represents the mass fraction of Mo.

5. The nickel-based alloy according to claim 1, characterized in that Measured by volume fraction, the cast structure of the nickel-based alloy includes: γ phase ≧70%, BCC phase ≤10%, μ phase ≤3%, and б phase ≤2%.

6. A method for preparing the nickel-based alloy according to any one of claims 1 to 5, comprising the following steps: The nickel-based steel liquid is subjected to vacuum refining, and when the TO of the nickel-based steel liquid is less than or equal to 0.002%, an alloy containing Cr, Ce, Mo, Co and Cu is added to the nickel-based steel liquid to obtain an alloyed steel liquid; The alloyed nickel-based steel liquid is poured to obtain the nickel-based alloy.

7. A fuel cell interconnection plate, said fuel cell interconnection plate being made of the nickel-based alloy according to any one of claims 1 to 5.

8. The fuel cell interconnection plate according to claim 7, characterized in that: The fuel cell interconnect plate includes at least one of the following properties: ASR≤0.004Ω·cm at 900℃ for 10000h 2 ; The thermal expansion coefficient at 900°C is 10×10 -6 / K~12×10 -6 / K; The total thickness of the oxide film after oxidation at 900℃ for 30,000 hours is less than 10μm; 400mA / cm at 900℃ 2 The cathode deposited Cr content of the current polarization for 4000h is ≤0.004mg / cm 2 ; 900℃ tensile strength ≥360MPa; 900℃ yield strength ≥320MPa.

9. A method for preparing a fuel cell interconnection plate according to claim 7 or 8, the method comprising: The nickel-based alloy according to any one of claims 1 to 4 is subjected to rolling, stamping and solution treatment to obtain a fuel cell interconnection plate.

10. The method according to claim 9, characterized in that The solution treatment includes the following parameters: the solution treatment temperature is 1050°C to 1080°C, the holding time is 1h to 3h, the hydrogen injection volume is ≥ 20m 3 / h.

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