Abstract: Solid oxide fuel cell (SOFC) interconnects are critical components for the durability of stack performance. Conventional materials such as stainless steels or ceramics face challenges including poor oxidation resistance, excessive weight or low machinability. This study proposes an innovative multilayer ceramic composite structure with the configuration of LaB6-hBN/TiB2-hBN/LaB6-hBN, and investigates high-temperature oxidation behavior and electrical conductivity. The composites are fabricated by spark plasma sintering (SPS), with precise control over powder composition and loading sequence to form a well-defined layered architecture: the top and bottom surface layers, rich in LaB6, provide excellent oxidation resistance and high-temperature electrical conductivity, while the middle matrix TiB2-hBN layer contributes to mechanical robustness and processability. Experimental results demonstrate that the multilayer sample A2 (with top and bottom surface layers each containing 7.5vol% LaB6 and 2.5vol% hBN, and a middle layer of 40.0vol% TiB2 and 40.0vol% hBN) exhibits remarkable oxidation resistance. After being oxidized at 600℃ for 100 hours, it still maintains a high-temperature conductivity of approximately 3 S/cm. The material's compressive strength and strain can reach 450 MPa and 1.67%, respectively, and it also has good processability. XRD, SEM, and EDS analyses confirm that LaB6 in the top and bottom surface layers remains largely unoxidized under long-term air exposure at 600℃, while TiB2 in the middle layer forms an oxidation barrier layer with 20 μm thick TiO2 film, which effectively suppresses inward oxidation. The hBN-TiB2-LaB6 structure, with hBN enriched in the interface layer, ensures a conductive pathway at the interface. This work presents a feasible and effective strategy for designing advanced SOFC interconnects with an optimal balance of oxidation-resistant, electrical, and mechanical properties, offering valuable insights into material selection and structural design for high-temperature energy applications.

Key words: solid oxide fuel cell interconnect, high-temperature conductive ceramics, multilayer composites, metal boride, hexagonal boron nitride

摘要： 固体氧化物燃料电池(Solid Oxide Fuel Cell, SOFC)连接体对电堆性能的稳定性至关重要。传统连接体材料如不锈钢或导电陶瓷存在高温抗氧化性差、质量过重或难加工等问题。为此，本研究设计并制备了一种新型叠层陶瓷复合材料(LaB6-hBN/TiB2-hBN/LaB6-hBN)，研究了其高温抗氧化性及导电性能。采用放电等离子烧结(SPS)工艺，通过控制粉体成分和添加顺序，成功制备具有层状结构的复合材料：上下表层以LaB6-hBN为主体，提供良好的抗氧化与高温导电性能；中间层以TiB2-hBN为主体，赋予材料良好的力学与可加工性能。研究结果表明，叠层样品A2 (上下表层成分：7.5vol% LaB6+2.5vol% hBN；中间层成分：40.0vol% TiB2+40.0vol% hBN)抗氧化性能显著，在600℃氧化100 h后仍保持约3 S/cm的高温电导率，且氧化后材料抗压强度和应变可达450 MPa和1.67%，同时具备良好的可加工性。分析表明，上下表层的LaB6在600℃氧化100 h后未发生明显氧化，中间层的TiB2氧化生成的TiO2分布在近表面20 μm范围内，有效抑制了进一步氧化，界面层富集hBN的hBN-TiB2-LaB6结构保证了界面处的导电通路。本研究为SOFC连接体材料的开发提供了新的设计思路，证实了通过多层结构实现抗氧化、导电与力学性能协同优化的可行性。

关键词: 固体氧化物燃料电池连接体, 高温导电陶瓷, 叠层复合材料, 金属硼化物, 六方氮化硼