钙钛矿型La1-xSrxCoO3-δ粉体的制备及其在银基电接触材料中的应用

Preparation of perovskite La1-xSrxCoO3-δ Powders and its application in Silver based electrical contact materials

摘要:

采用溶胶-凝胶法和粉末冶金工艺分别制备了颗粒状和网孔状La_0.5Sr_0.5CoO_3-δ(LSCO)粉体及其Ag-LSCO电接触复合材料。优化了溶液pH,溶胶预处理温度等工艺对LSCO粉体微结构的影响,并考察成型压力,烧结温度等对Ag-LSCO材料电学、力学性能的影响研究。采用扫描电镜、X-射线衍射仪、D60K数字金属电导率测量仪和HVS-1000型数显显微硬度计等对LSCO粉体及Ag-LSCO电接触材料进行了微观形貌、物相结构、电导率与硬度等性能表征。结果表明：以柠檬酸为单一胶凝剂,当pH为9.5,在700℃烧结8h可获得颗粒状LSCO_p粉体；而以柠檬酸和EDTA为复合胶凝剂时,于前驱体溶液pH=9.5,溶胶预处理温度200℃,烧结温度700℃,8h条件下合成网孔块体结构的LSCO_w粉体。经成型压力及烧结制度的优化结果可知,成型压力(1100MPa)、烧结温度900℃,6h 为制备Ag/LSCO_w电接触材料的最佳工艺参数。相比于Ag-LSCO_p电接触复合材料,Ag-LSCO_w表现出更低的电阻率(2.5μΩcm)。

Abstract:

The LSCO_p and LSCO_wpowders were synthesized by sol-gel method. And then Ag-LSCO_pand Ag-LSCO_w electrical contact composites were fabricated by high-energy ball milling and sintering process with LSCO powders as the second reinforcement phase. The effects of pH and pre-treated sol temperature on the microstructure of LSCO powder were optimized. The effects of molding pressure and sintering temperature on the electrical and mechanical properties of Ag-LSCO contacts were investigated. The microstructure and phase of LSCO powders and Conductivity and hardness characteristics of the Ag-LSCO electrical contact material were tested by scanning electron microscopy (SEM), X-ray diffractometer(XRD), D60K digital metal conductivity meter and HVS-1000 digital microhardness tester. The results showed that LSCO_p was obtained at pH= 9.5 and sintering temperature of 700℃ for 8 h when using single citric acid as gelling agent, but LSCO_w was obtained with citric acid and EDTA used as complex gelling agents. Ag/LSCO_w electrical contact materials were prepared with the molding pressure of 1100 MPa, sintering temperature of 900℃ and sintering time of 6h. And when using LSCO_w powder as the second reinforcement phase, Ag-LSCO_w electrical contacts showed lower resistivity than that of Ag-LSCO_p.