**3.1 Surface texture of coatings**

Average roughness of different coatings is indicated in Table 4.

It is evident that the average roughness values of alumina coatings cast iron substrates vary between 3.5 and 5.5 m and it is between 4.5 and 7.2 m in case of ZrO25CaO coatings. Top coat of test samples such as CI-S4, CI-S5, CI-S6 possess mounds of molten and unmolten particles contribute to the increase in roughness. Flowability of ZrO25CaO is less compared to alumina and this contributes to the formation of mounds and affects the quality of the surface texture of the coating. Increase in porosity as well as the coating thickness enhances the roughness of top coat. Coating roughness also increases with enhanced coating thickness. Similar observations regarding to the effect of coating thickness on roughness were reported by O. Sarikaya [17].

Fig.2 shows the roughness profiles of few coating systems (CI-S2 and CI-S6) with average roughness (Ra) as the main parameter.

Fig. 2. Roughness profiles of coating systems
