| Summary: | ABSTRAK
Feldspars addition on the breakdown voltage as well as mechanical strength of the medium voltage isolator has been investigated. The glaze properties were studied in particular its relationship to the dielectric and mechanical strengths. The breakdown voltage before and after glazing was examined. The averages breakdown voltage of ceramic body is 14.7 kV before glazing, and it increases after glazing with an average breakdown voltage ranging from 16-20 kV. Firing was done at temperature 1300 °C (with and without glazing) and six different compositions (A-F) were used in this investigation. The most positive result in this investigation was found in composition A, and the average glaze thickness is 0.318 mm with breakdown voltage of 5.51 kV (alternating current). The breakdown voltage increases linearly with the glaze thickness, and the average leaking current in this composition is 4.56 X 10-4. The average porosity of ceramic body ranging from 1.0 to 5.36 percent which is quite satisfactory within the limit of experimental observation and industrial application. The averages impact strength ranging from 0.26 cm-Kg to 0.57 cm-Kg. X-ray diffraction study shows that for glaze A, sillimanite was the main phase responsible for high breakdown voltage and high impact strength, and it has orthorhombic crystal structure. While for glaze B, indialite phase was responsible for the lowest breakdown potential and lowest impact strength, and it has hexagonal crystal structure.
Key word: feldspar, voltage ceramic isolator,
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