Experimental investigation of hydrophobic characteristics of aluminum oxide on carbon fiber sheet with varied solvent content

Abstract This dip coating research investigates the hydrophobic properties of aluminium oxide coatings on carbon fiber sheets using ethanol, polyvinyl alcohol (PVA), and acetone at varying ratios. The dip coating technique applies Al 2 O 3 coatings to carbon fiber sheets. At 5%, 10%, and 15%, ethanol is combined with Al 2 O 3 . These amounts of PVA and acetone are also produced by combining Al 2 O 3 with PVA and ethanol. Samples are heat-treated in a hot air oven at 250℃ to 350℃ after 48 h of drying. The contact angle measurements reveal that increasing Al 2 O 3 concentrations enhances hydrophobicity. The coatings lack diffraction peaks, indicating that they are amorphous. No Al₂O₃ diffraction peaks in epoxy–Al₂O₃ coatings suggest a homogeneous dispersion of alumina nanoparticles in the epoxy matrix. XRD (X-ray diffraction) analysis of the 5 wt% Al₂O₃ coating shows uniformity, no particle agglomeration, and an amorphous nature. There is a single peak at ~ 20°, corresponding to the (002) crystallographic plane of the carbon substrate. No distinguishable Al₂O₃ peaks are found, indicating homogeneous dispersion. The untreated carbon fiber sheet has a contact angle of 37°, whereas the coated sample has contact angles of 98.80°, 102.80°, and 103.80° for Al 2 O 3 + Ethanol, PVA, and Acetone, respectively. Each sample’s coating was 10 mm x 50 mm, and the solution volume was constant, but the weight % of aluminium oxide fluctuated.