| Because of it’s great energy density, linear I-V characteristics, smaller resistance temperature coefficient, adjustable resistivity and low cost, ZnO-based pluse power resistance has desired for neutral grounding resistance(NGR), circuit breaker opening and closing resistance, field-suppressing resistance, and has received widely attention and research. In this paper, the ohmic electrode material, sintering process, formula and ability to withstand against high energy shock pulses of Al-doped ZnO power resistor ceramics were systematically studied. The main work and conclusions of this research are as follows:1. The influence of Zinc-containing silver paste electrode, Al sputtering electrode and Ti/Au alloy sputtering electrode to the ZnO power resistor ceramics were studied respectively. The results show that the contact resistance between the Zinc-containing silver electrode that are sintered in an N2 atmosphere and the Al-doped ZnO ceramics was reduced; the contact resistance between the Al electrode and Al-doped ZnO resistor ceramics is ohmic contact when the samples were annealed,and the resistivity is 3.94Ω ? cm when 300 ℃ annealing, but it is easily oxidized to be forming a thin oxide layer and bringing additional resistance; the contact resistance between the Ti/Au alloy electrode and Al-doped ZnO resistor ceramics was excellent ohmic contact when samples were annealed, and the resistivity is 0.503Ω ? cm when 400 ℃ annealing.2. The effects of Al(NO3) 3 ? 9H2 O additive contents on the microstructure and electrical properties of ZnO-based linear resistor were investgated. The result show that the electrical properties of Al(NO3) 3 ? 9H2O-doped ZnO linear resistor was better than single Al2O3-doped ZnO linear resistor, when Al(NO3) 3 ? 9H2 O content within 8mol%, resistivity was 0.79 ~ 22.89Ω ? cm, nonlinear coefficient was less than 1.2 and resistance temperature coefficient was-1.0x10-3 ~-2.2x10-3/℃. 20 us pluse wave were used to test Al(NO3) 3 ? 9H2O-doped ZnO linear resistor samples.they could endure the impacts of high energy, and their energy density were greater than 1000J/cm3, after being impacted, resistance decreased within 5 %.3. The electrical properties of LSCO(La0.5Sr0.5CoO3) ceramic resistors and the effects of sintering process on LSCO ceramic resistors were invested. The result show that the density of LSCO ceramic resistors increased first and then decreased when the sintering temperature in the range of 1240 ~ 1300℃;And when sintered at 1270℃, density, resistivity, nonlinear coefficient and resistance temperature coefficient of LSCO ceramic resistors was 6.250g/cm3, 0.5Ω·cm,1.04 and-3.33x10-3/℃ respectively. After being sticked with coppers and packaged with epoxy resin, LSCO ceramic resistors were impacted with 20 us higher energy pluse waves. The result show that LSCO ceramic resistors could endure the impacts of high energy, their dendity greater than 8000J/cm3. After being impacted, the contact between electrode and LSCO ceramics was worse and resistance increased greatly.Finally Combined with practical application, ZnO+1.5mol%Al2O3 ceramic power resistors which their size is Φ125x10.5mm were prepared. These samples were welded with copper electrode, encapsulated with epoxy resin and then tested with 8.7ms stronger energy and higher current pluses. The result show that the power capacity of ZnO power resistors is 4.17 kJ when these samples were intact after the pros and cons of each five times testing. Therefore ZnO ceramic resistors can be used to prepare power resistors with power capacity 3.4kJ. |
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