Investigation of Electrical and Chemical Properties of an especial Enamel for Ni-Cr Wire-wound Resistor

In present work a tested enamel coat for Ni-Cr wire-wound resistor is studied for its electrical and chemical properties. In the present work it is tried to find appropriate coating by testing different compounds. Results showed that the optimum enamel is the compound with 1 wt% cobalt oxide، 3 wt% chromium oxide and firing temperature 840˚C. Variation of the electrical conduction of the enamel with temperature is measured by an instrument designed by Rasch-Hinrichsen et al. Results indicate that with increasing the temperature to 275˚C electrical conduction reaches to 10-7. 60 Ω-1. cm-1. Dielectric strength test shows 100 KV/cm for breakdown voltage. Weight loss in different liquids with various pH shows that the most chemical resistance is yielded in water and for neutral pH.