A Statistical Analysis to Study the Effect of Silicon Content, Surface Roughness, Droplet Size and Elapsed Time on Wettability of Hypoeutectic Cast Aluminum–Silicon Alloys

In this study, the effect of silicon content, surface roughness, water droplet size, and elapsed time on contact angle (CA) of Aluminum-Silicon alloys were examined. To study wettability the static water contact angle was measured on a given sample using a goniometer. A laser confocal microscopy was used for measuring surface roughness. A full factorial design was utilized for the design of the experiment that includes all possible combinations of the independent factors and their levels (120 combinations). CA for each combination was measured three times, so in total 360 CA measurements were performed. To find the significant factors in CA variation and correlation between the significant factors and CA, Analysis of Variance (ANOVA) and Regression Analysis were performed, respectively. A significance level (α) of 0.05 was used for all statistical analyses. Contact angle values averaged 77° ± 5° with maximum value of 90º and minimum value of 64º, respectively. ANOVA results show that surface roughness and droplet size are significant factors. Regression analysis shows that CA increases by increasing surface roughness and water droplet size.