Varistor is an electronic component that is commonly used in sensitive electronic circuit for protection against unpredictable voltage surge. In microprocessor based electronic devices, the utility switching of the operation on unloaded line may give rise to overvoltage too but in small amplitude since the normal operating voltages are in 120 V range. Hence, to overcome this problem in electronic devices, it is necessary to implement a small dimension varistor that is able to clamp any surge in voltage above the normal operating voltage but in lower range. The factor that determines the low voltage varistor characteristics is the electrical properties of the sample which is highly depending on the defect states of the grain boundaries of varistor sample. The defect states will be modified by adding different types of metal dopant that is expected to differently modify the microstructure and electrical characteristics of the varistor.
Plasma electrolytic oxidation (PEO) will be utilized as a method to produce a thin oxide layer on the zinc metal surface and the incorporation of metal dopant particles will agglomerate into oxide coatings producing zinc oxide based varistor with dopant particles coated on the surface. Different types of metal dopant will be used as the parameter of this research project to investigate the effect of different metal dopant on the electrical nonlinearity of the coating produced. The coated sample will be characterized accordingly based on the microstructure characteristics, mechanical properties of the coating and the electrical properties that will eventually evaluates the performance of the varistor sample.
By Nur Athirah binti M Sukrey
Supervisor: Assoc. Prof. Dr. Bushroa Abdul Razak
Produced by PEO for varistor
Last Update: 27/10/2022