Pengaruh Aditif Bi203 Terhadap Sifat Fisis dan Listrik dari Keramik Varistor ZnO

Abstract

Ceramic Varistor ZnO has been made by using raw materials ZnO and additive BizO:. The application of varistor ZnO is for circuit overvoltage protection in circuits electronic, machinery. and distribution of electrical field. There are two variables for this experiment such as : variables of additive are 0%, 2.5%, 5%, 7.5%, and 10% Bi;Os , and variables of temperature sintering are 900. 950, 1000, and 1050 °C. The mixing process of raw materials was done by using a magnetic stirrer with acetone solution, then the mixed powder was dried at 60°C. then grinding and sieving 400 mesh. Then the powder was pressing at 50 MPa and sintered at variation temperature, also each sintering temperature was hold for 2 hours. After sintering, the samples were characterized such as : measurement of density and porosity, and microstructure by using SEM and XRD. Characterization results show that samples without additive do not show properties as varistor, they have very low of coefficient non linier about 0.33 — 1.73. The samples with additive 7.5 % BizO, and sintering temperature 1000 - 1050 °C show as Varistor with characteristic : density about 5,60 g/cm’. porositas about 0.02 %. coefficient non linier about 64, and non finier voltage about 1 kViem. The XRD results show that it found a dominant phase ZnO and minor phase BisOs. also according the observation from photos SEM that grain boundary is formed at samples with additive > 2,5 % BizOs.