Sliding Wear Resistance and Microhardness of Epoxy ClayNanocomposite Coatings

Epoxy clay nanocomposites were prepared by ultrasonication and were applied on flat and cylinder or pin shaped mild steel specimen for microhardness and sliding wear resistance test, respectively. The optimum thickness of coating that doesn't experience any substrate effect when indented was determined to be 200 microns. Microhardness was optimized by conducting microhardness tests as per Taguchi's technique (L9 orthogonal array). The input factors influencing the microhardness were nanoclay concentration (wt.%), sonication time (minutes), and curing time (days). From the main effects plot, it was observed that microhardness increases with increase in nanoclay concentration. As sonication time increases from 5 to 10 minutes, microhardness increases. But when sonication time increases from 10 to 15 minutes, microhardness decreases. The microhardness is maximum for a curing time of 3 days. The optimum levels of the three factors were 5 wt % of nanoclay, 10 minutes of sonication time and 3 days of curing. Nanoclay concentration was the most influencing factor followed by sonication time and curing time. The obtained output data was used to fit in a regression equation. Sliding wear resistance test was carried out using a pin on disc wear testing machine. Sliding wear resistance increases with increase in nanoclay concentration till 4 wt %. The sliding wear resistance does not change beyond 4 wt % which is due to agglomeration of nanoclay.