Nickel-based expansion alloy for metal connector of medium temperature plate type solid-oxide fuel battery

Abstract

The invention belongs to the alloy steel field, in particular to a nickel base expanding alloy used on an intermediate temperature flat-plate type solid oxide fuel cell metallic interconnector. The alloy has chemical compositions (in weight percent): Mo 18.0 to 24.0 percent, Cr 10.0 to 14.0 percent, Co 2.5 to 3.5 percent, W 3.5 to 4.5 percent, Ti 1.0 to 1.5 percent, Mn 0.8 to 1.2 percent, Si<=0.05 percent, La<=0.02 percent, Y<=0.01 percent, C<=0.005 percent, S<=0.005 percent, P<=0.005 percent, balance Ni. Compared with the prior art, the alloy has the advantages of good compatibility of expansion properties with surrounding materials in the solid oxide fuel cell operational environment, good pyroconductivity, oxidation resistance and mechanical property. The tensile strength of alloy is higher than 1100MPa under room temperature, the elongation at break is higher than 18 percent, and the coefficient of expansion from the room temperature to 1000DEG C is controlled under 15x10<-6>DEG C<-1>.

Description

technical field [0001] The invention belongs to the field of alloy steel, and in particular relates to a Ni-based expansion alloy for a metal connector of a medium-temperature flat solid oxide fuel cell (SOFC). Background technique [0002] A solid oxide fuel cell is a device used to directly convert chemical energy into electrical energy. At present, the structure of oxide fuel cell SOFC is roughly divided into two types, tube type and flat plate type. Tubular SOFC generally works at about 1000°C. Its advantages are simple sealing and easy assembly into relatively high-power modules. The problems it faces are low power density and complicated preparation process. Compared with tubular SOFC, planar SOFC has high power density and simple preparation process, but the problem it faces is the difficulty of sealing. In solid oxide fuel cells, the interconnect material has two main functions, the function of connecting the single cells and isolating the fuel gas. The connector ...

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Problems solved by technology

However, the oxidation of metal materials as connector materials in the working environment is inevitable, and the formed oxide film leads to a sharp increase in the contact resistance of the connector and its adjacent components, resulting in a sharp drop in the efficiency of the battery.

[0004] At present, the alloy materials used as connectors mainly include Fe-based, Ni-based, and Cr-based alloys. These alloy materials usually contain anti-oxidation components such as Cr and Al, and the surface of the alloy forms Cr 2 o 3 and Al 2 o 3 protective layer, reducing the oxidation rate of the alloy, although Al 2 o 3 The oxidation rate of the oxide layer is only Cr 2 o 3 1 / 10 of that, but due to its low conductivity, it is not suitable for oxidation-resistant alloying elements as SOFC connector materials

[0005] Introduced in CN1149892A is Fe-Cr-W-M, M is one or more than two kinds of a group of elements composed of Y, Hf, Ce, La, Nd and Dy, and adding a trace element B, obtained a material with the same expansion properties as zirconia. New alloy materials with matching coefficients have excellent high-temperature oxidation resistance, but the high-temperature electrical conductivity and mechanical properties of the materials need to be further studied

However, due to the variety of alloying elements, many uncertain factors are brought in the production process, the composition is not easy to control, and the cost of materials is relatively high.

Introduced a kind of Fe-Cr (15~30wt%) base alloy among CN1468970A, add the alloying element Ni, Al, Zr of 0.1~1.0wt%, the alloying element Si of 0.1~1.5wt%, the obtained alloy material 600 The coefficient of expansion at ~1000°C is 11~13×10 -6 K -1 between, which matches the expansion coefficient of existing electrolyte materials, but the high temperature oxidation resistance of the alloy needs to be further improved

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