还原再氧化工艺制备Pr-ZnO基压敏陶瓷
发布时间：2019-06-22 10:35
【摘要】：叠层片式压敏电阻器具有非线性高、响应速度快、通流能力强等优点,在电路中可以起到过电压保护、吸收瞬间电压浪涌等作用。目前叠层片式压敏电阻器采用的内电极主要是贵金属Ag或Ag/Pd合金,使用贵金属不仅制造成本高,另外Ag在高温下容易渗入叠层而恶化压敏性能。而如果采用贱金属作为内电极,由于贱金属在传统的在空气气氛中烧结极易被氧化,影响其导电性。因此,本文通过还原再氧化工艺制备出低电压的压敏陶瓷,即先在保护气氛烧结保护贱金属不被氧化,然后在空气中较低温度下热处理提升压敏性能。这种新的方法为制备叠层片式压敏电阻采用贱金属做电极提供了可能。首先研究了ZnO-Pr6O11-Co2O3-x MnO2材料在N2中烧结特性和电性能,发现N2中烧结后材料失重高、密度低、平均晶粒尺寸小、电阻率低。再氧化后材料可以获得压敏性能,并且在900℃范围内,再氧化温度升高材料的压敏性能持续上升。此外,烧结温度升高,出现由于密度上升而材料难以氧化的现象,最后在1230℃、MnO2掺杂量为0.25 mol%取得最佳压敏性能(压敏场强208 V/mm,非线性系数11,漏电流15.4?A)。液相高温挥发和冷却收缩给材料带来气孔和裂纹,可降低再氧化难度。所以又研究了可带来液相的助烧剂BN对制备工艺的影响,发现BN的最佳掺杂量为1.5mol%,再氧化温度和烧结温度分别降低至850℃和1193℃。850℃可使材料均匀氧化,更高温度氧化压敏性能趋于稳定(压敏场强151 V/mm,非线性系数23,漏流3.7?A)。受液相的作用,烧结温度对晶粒大小和电性能影响大幅提升。最后发现再氧化的作用主要包括:(1)促进晶间相沿晶界分布,(2)晶界富集的氧可使晶界中锌填隙和氧空位的浓度降低,最终提高了势垒高度和材料的压敏性能。
[Abstract]:Laminated chip varistors have many advantages, such as high nonlinear, fast response speed, strong current flow ability and so on. They can play the role of overvoltage protection and instantaneous voltage surge in the circuit. At present, the inner electrode of laminated chip varistor is mainly precious metal Ag or Ag/Pd alloy. The use of precious metal not only has high manufacturing cost, but also Ag is easy to infiltrate into the stack at high temperature to deteriorate the varistor performance. If base metal is used as internal electrode, it is easy to be oxidized because base metal is sintered in air atmosphere, which affects its conductivity. Therefore, low voltage varistor ceramics were prepared by reduction and reoxidation process, that is, base metals were sintered in protective atmosphere to protect base metals from oxidation, and then heat treatment at lower temperature in air to improve varistor properties. This new method makes it possible to prepare laminated chip varistors using base metal as electrode. Firstly, the sintering characteristics and electrical properties of ZnO-Pr6O11-Co2O3-x MnO2 materials in N2 were studied. It was found that the sintered materials in N2 had high weightlessness, low density, small average grain size and low resistance. The varistor properties of the materials can be obtained after reoxidation, and the varistor properties of the materials increase with the increase of reoxidation temperature in the range of 900 鈩，
本文编号：2504500
[Abstract]:Laminated chip varistors have many advantages, such as high nonlinear, fast response speed, strong current flow ability and so on. They can play the role of overvoltage protection and instantaneous voltage surge in the circuit. At present, the inner electrode of laminated chip varistor is mainly precious metal Ag or Ag/Pd alloy. The use of precious metal not only has high manufacturing cost, but also Ag is easy to infiltrate into the stack at high temperature to deteriorate the varistor performance. If base metal is used as internal electrode, it is easy to be oxidized because base metal is sintered in air atmosphere, which affects its conductivity. Therefore, low voltage varistor ceramics were prepared by reduction and reoxidation process, that is, base metals were sintered in protective atmosphere to protect base metals from oxidation, and then heat treatment at lower temperature in air to improve varistor properties. This new method makes it possible to prepare laminated chip varistors using base metal as electrode. Firstly, the sintering characteristics and electrical properties of ZnO-Pr6O11-Co2O3-x MnO2 materials in N2 were studied. It was found that the sintered materials in N2 had high weightlessness, low density, small average grain size and low resistance. The varistor properties of the materials can be obtained after reoxidation, and the varistor properties of the materials increase with the increase of reoxidation temperature in the range of 900 鈩，
本文编号：2504500
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