【摘要】：疊層片式壓敏電阻器具有非線性高、響應(yīng)速度快、通流能力強(qiáng)等優(yōu)點(diǎn),在電路中可以起到過(guò)電壓保護(hù)、吸收瞬間電壓浪涌等作用。目前疊層片式壓敏電阻器采用的內(nèi)電極主要是貴金屬Ag或Ag/Pd合金,使用貴金屬不僅制造成本高,另外Ag在高溫下容易滲入疊層而惡化壓敏性能。而如果采用賤金屬作為內(nèi)電極,由于賤金屬在傳統(tǒng)的在空氣氣氛中燒結(jié)極易被氧化,影響其導(dǎo)電性。因此,本文通過(guò)還原再氧化工藝制備出低電壓的壓敏陶瓷,即先在保護(hù)氣氛燒結(jié)保護(hù)賤金屬不被氧化,然后在空氣中較低溫度下熱處理提升壓敏性能。這種新的方法為制備疊層片式壓敏電阻采用賤金屬做電極提供了可能。首先研究了ZnO-Pr6O11-Co2O3-x MnO2材料在N2中燒結(jié)特性和電性能,發(fā)現(xiàn)N2中燒結(jié)后材料失重高、密度低、平均晶粒尺寸小、電阻率低。再氧化后材料可以獲得壓敏性能,并且在900℃范圍內(nèi),再氧化溫度升高材料的壓敏性能持續(xù)上升。此外,燒結(jié)溫度升高,出現(xiàn)由于密度上升而材料難以氧化的現(xiàn)象,最后在1230℃、MnO2摻雜量為0.25 mol%取得最佳壓敏性能(壓敏場(chǎng)強(qiáng)208 V/mm,非線性系數(shù)11,漏電流15.4?A)。液相高溫?fù)]發(fā)和冷卻收縮給材料帶來(lái)氣孔和裂紋,可降低再氧化難度。所以又研究了可帶來(lái)液相的助燒劑BN對(duì)制備工藝的影響,發(fā)現(xiàn)BN的最佳摻雜量為1.5mol%,再氧化溫度和燒結(jié)溫度分別降低至850℃和1193℃。850℃可使材料均勻氧化,更高溫度氧化壓敏性能趨于穩(wěn)定(壓敏場(chǎng)強(qiáng)151 V/mm,非線性系數(shù)23,漏流3.7?A)。受液相的作用,燒結(jié)溫度對(duì)晶粒大小和電性能影響大幅提升。最后發(fā)現(xiàn)再氧化的作用主要包括:(1)促進(jìn)晶間相沿晶界分布,(2)晶界富集的氧可使晶界中鋅填隙和氧空位的濃度降低,最終提高了勢(shì)壘高度和材料的壓敏性能。
[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，

本文編號(hào)：2504500