synthesis of a special enamel for Nickel-Chrome resistor and characterizing the viscosity and surface tension

In the present work, attempts have been made to find appropriate coating by testing different compounds. Results showed that the optimum enamel is a compound with 1 wt.% cobalt oxide, 3 wt.% chromium oxide (in addition to hundred percent) with the firing temperature of 840 ˚C. Constants of VFT equation were determined by examination of melting behavior of the optimum enamel and measurement of the transition and softening temperatures (Tg and Ts). Results also showed that in the firing temperature, the viscosity of coating is 103.8 Pa.s, the contact angle (wetting of melt with the ceramic substrate) is 135° and the surface tension of the melt is 245.1 mN/m.