外文翻譯---復(fù)合金屬和冷軋在固體氧化物燃料電池中的應(yīng)用技術(shù)（英文）

1、Journal of Power Sources 152 (2005) 40–45Short communicationClad metals, roll bonding and their applications for SOFC interconnects?Lichun Chen a,?, Zhenguo Yang b, Bijendra Jha a, Guanguang Xia b, Jeffry W. Stevenson ba

2、 Engineered Materials Solutions, 39 Perry Avenue, Attleboro, MA 02703, USA b Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA 99352, USAReceived 14 December 2004; accepted 5 January 2005 Available o

3、nline 22 March 2005AbstractMetallic interconnects have been becoming an increasingly interesting topic in the development in intermediate temperature solid oxide fuel cells (SOFC). High temperature oxidation resistant al

4、loys are currently considered as candidate materials. Among these alloys however, different groups of alloys demonstrate different advantages and disadvantages, and few if any can completely satisfy the stringent require

5、ments for the application. To integrate the advantages and avoid the disadvantages of different groups of alloys, clad metal has been proposed for SOFC interconnect applications and interconnect structures. This paper gi

6、ves a brief overview of the cladding approach and its applications, and discuss the viability of this technology to fabricate the metallic layered-structure interconnects. To examine the feasibility of this approach, the

7、 austenitic Ni-base alloy Haynes 230 and the ferritic stainless steel AL 453 were selected as examples and manufactured into a clad metal. Its suitability as an interconnect construction material was investigated. ©

8、 2005 Elsevier B.V. All rights reserved.Keywords: Clad metals; Roll bonding; SOFC interconnect1. IntroductionRecent advancements in solid oxide fuel cell (SOFC) tech- nologies have allowed a reduction in SOFC operating t

9、em- peratures to an intermediate range (600–800 ?C) [1–3]. This resulted in increased interest in development of cost-effective metallic interconnects to replace the traditional ceramic ma- terials that are used in high

10、temperature (900–1000 ?C) SOFC stacks [4–6]. There are three primary functions of intercon- nects in common SOFC designs: (1) to provide an electrical conductive path that permits an in-series connection of in- dividual

11、cells; (2) to separate the fuel and oxidant gas paths between individual cells; (3) to act as the primary structural element to maintain the overall mechanical support and sta- bility of the stack and to provide mechanic

12、al connection sur- faces for gas path sealing materials. Therefore, during SOFC? This paper was presented at the 2004 Fuel Cell Seminar, San Antonio, TX, USA. ? Corresponding author. Tel.: +1 508 342 2135; fax: +1 508 34

13、2 2535. E-mail address: lchen@emsclad.com (L. Chen).operation, the interconnects must be thermally, chemically and mechanically stable during simultaneous exposure to an oxidizing atmosphere at the cathode side and a red

14、ucing at- mosphere at the anode side for thousands of hours at elevated temperatures with numerous thermal cycles. The intercon- nect must be stable towards any sealing materials with which it is in contact. In addition,

15、 the interconnects must be chemi- cally compatible with electrical contact materials, which are used to minimize interfacial contact resistance, and/or the electrode materials. More specifically, the metallic intercon- n

16、ect materials are required to have excellent surface stabil- ity, i.e. oxidation and corrosion resistance, between 600 and 800 ?C, high long-term electrical conductivity, good thermo- mechanical stability and compatibili

17、ty with other stack com- ponents (e.g. seals, electrodes), as well as low cost. Overall, there are three groups of high temperature oxi- dation resistant alloys based on what protective oxide scales are formed; these are

18、 alumina forming, silica forming and chromia forming alloys [5]. Alumina forming Ni–Cr–Al, Co–Cr–Al and low cost Fe–Cr–Al alloys have extremely slow-growing alumina scale that is protective against oxida-0378-7753/$ – se

19、e front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.jpowsour.2005.01.05542 L. Chen et al. / Journal of Power Sources 152 (2005) 40–45Fig. 1. Schematic of roll bonding process for manufacturing cla

20、d metal.duce a solid state joint between the original individual metal pieces. During roll bonding, no filler or adhesive agent is in- volved. Generally there are two types of roll bonding: hot roll bonding and cold roll

21、 bonding. Hot roll bonding is a process that involves external heating, while no external heat is ap- plied during cold roll bonding. Cold roll bonding has several advantages over hot roll bonding, including more uniform

22、 in- dividual layer thickness ratio, good surface quality and lower cost. Before roll bonding, the surfaces to be bonded must be properly cleaned and prepared to remove any barriers to bonding (Fig. 1). Chemical and mech

23、anical cleanings are two common methods used to remove organic matter and surface oxides. An alkaline detergent is normally applied to remove oil or organic matter and a diluted acid solution is used to re- move surface

24、oxides. Mechanical cleaning may also provide rough surfaces, which provide a greater amount of surface asperities and promote localized shear deformation to break unavoidable surface oxide films during cold roll bonding.

25、 During the bonding process, high reduction in thickness of the materials (capable of up to 60% or more in a single rolling pass) is achieved under high pressure at the roller. The high reduction generates a great amount

26、 of heat and creates vir- gin surfaces on the materials being bonded. The fresh, virgin surfaces along the bond interface are in a self-enclosed en- vironment, where oxidation cannot occur, and therefore do not have bond

27、-impeding oxide barriers. A bond (normally a mechanical bond) in the layered composite is thus obtained through interfacial mechanical locking and atomic affinity between the two metals. After roll bonding, annealing is

28、nor- mally performed (Fig. 1) to obtain or secure a metallurgical bond. In addition to recovery and recrystallization of highly cold-worked microstructures during annealing, residual or- ganic impurities can be gasified

29、and diffused away from the bond interface, and diffusion can occur along and across the bond interface, creating a “common lattice structure”. Some of the clad metal systems do not need a separate annealing process after

30、 cold-roll bonding because self-annealing oc- curs during and after bonding. After the above processes, the clad metals can be further processed by any of conventional strip metal manufacturing processes (e.g., cold-roll

31、ing, an- nealing, pickling, leveling and slitting) to specific required sizes and temper. They can be roll-formed, stamped, drawn and joined into a required component or part. As clad met-als can be produced by roll bond

32、ing and further processed in coil form, their manufacturing has high productivity and is economically cost-effective.4. Concepts for SOFC interconnectsTwo concepts have been proposed in preparing clad met- als for SOFC i

33、nterconnect applications. The first concept is to make simple clad metals by roll bonding of two or three layers of metals that typically have different compositions and properties. The second concept is to surface-alloy

34、 or - modify the clad metals through roll bonding and diffusion. In the first concept, for example, a ferritic stainless steel with an appropriate level of chromium and relatively low CTE can be used as the center core o

35、r back base in a clad metal sys- tem while a relative high CTE austenitic high temperature oxidation resistant alloy is used to form a thin surface layer in the clad metal. The ferritic stainless steel keeps the CTE of t

36、he clad metal to a value that is acceptable to stack de- signers, while lowering the interconnect cost. The austenitic high temperature oxidation resistant alloy, such as a Ni-base superalloy, provides excellent surface

37、stability as well as en- hances the structural stability. As a result, the clad metal inte- grates the advantages of Ni-base alloys and ferritic stainless steels, while their disadvantages are avoided. In the second conc

38、ept, a clad metal is first made by roll bonding of a base metal with one thin outer layer at one side or two thin layers at both sides of the base metal. This is followed by a spe- cial heat treatment during which diffus

39、ion alloying occurs on the surface of the clad metals. The surface alloying or modification offers the flexibility to modify the surface alloy composition of clad metals for improved chemical, electri- cal, and thermomec

40、hanical stabilities. For example, spinel phase is expected to form on the chromia scale to prevent chromium specie from volatilization which poises the cath- ode in the cell. Another hypothesis approach is to modify the

41、surface of alumina forming alloys to make the surface more conductive. In addition to the aforementioned advantages, the flexibil- ity of cladding also allows for addressing cathode and anode side issues separately, beca