預鍍銀層於2205-LSM 高溫電性之作用

Effect of Ag-Precoating on the Electrical Conductivity of 2205-LSM at High Temperature

本研究以 2205 雙相不銹鋼 （2205DSS） 為底材，並披覆La0.7Sr0.3MnO3（2205-LSM），以及在披覆La0.7Sr0.3MnO3 之前，於底材表面預先分別濺鍍2、4、5 μm 的Ag 層、網印Ag 層，再經1100 °C 氮氣氣氛高溫燒結後，探討2205-LSM於800 °C 的高溫氧化行為及Ag 於高溫電性的作用。實驗結果顯示，2205-LSM於800 °C 氧化1000 小時後，合金底材與LSM 界面形成的氧化物厚度相較於未氧化的2205-LSM 之氧化層增長1.56 ± 0.05 μm。但在500 ~ 750 °C 的ASR（area specific resistance），卻僅增加0.16 ~ 0.003 Ωcm2，其原因是Cr-Mn spinel比例提高或二價金屬離子摻雜Cr2O3，提昇了氧化層的導電性。在500 ~ 750 °C的電性量測，含中間Ag 層的2205-LSM 之ASR 均隨溫度提昇而下降，且其值也均低於2205-LSM 的ASR，其提昇的效果在低溫環境相較於高溫更為顯著。主要的代表是貴金屬縮短電子的傳導路徑 （current collection），增加電荷轉移效率，另為低價金屬離子摻雜氧化物與LSM 層，提昇整體導電性所致。使用濺鍍方式披覆不同Ag 層厚度的2205-LSM，在500 °C 測得的ASR 均低於2205-LSM 在750 °C 的ASR，2205DSS/Ag/LSM 用以作為金屬雙極板 （metallicinterconnects） 的材料，將可降低固態氧化物燃料電池 （Solid Oxide Fuel Cell,SOFC） 操作溫度。

This research focuses on the behavior and characteristics of oxidationfor 2205-LSM at 800 °C and its influence on electrical performance at hightemperature for a silver layer. LSM, Ag-LSM coated on 2205DSS byscreen print and sputter were sintered at 1100 °C in a nitrogen atmospherefor 30 to 90 minutes. Treated specimens were then oxidised at 800 °C. After oxidation at 800 °C for 1000 hours, an oxide layer was formed at theinterface between LSM and 2205DSS. An increase in thickness of oxidelayer was observed about 1.56 ± 0.05 μm but there were only small differencesin resistance measurements about 0.16 to 0.003 Ωcm2 as comparedwith non-oxidised specimens. During long-term oxidation, formationof Cr-Mn spinel derived from the reaction of Cr2O3 from 2205DSS andLSM was increased. Formation of Cr-Mn spinel would reduce resistancedue to its better conductivity. Regarding resistance measurements at temperaturesof 500 to 750 °C, ASR (area specific resistance) for noble metal-LSM coated 2205DSS was decreased with increase of temperature. ASR ofthe specimens was less than for LSM coated 2205DSS, especially at lowertemperatures because the noble metal acted as a current collector to providea better pathway for conduction of electrons, and low valence cations werediffused to the LSM and oxide layers. Different thicknesses of Silverwere coated on 2205-LSM by sputtering. According to our results, ASRfor Ag-LSM coated 2205DSS at 500 °C was less than for LSM coated 2205DSS at 750 °C. This demonstrated that metallic interconnects preparedwith Ag-LSM coated 2205DSS could lower working temperatures forSOFC.