Characterisation of multilayered sol–gel silica coatings on aluminium–SiC composites

• Published in: Surface & coatings technology Vol. 201; no. 6; pp. 3715 - 3722
• Main Authors: Rams, J., Ureña, A., López, M.D., López, A.J.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 04.12.2006; Elsevier
• Subjects: Aluminium alloy; Aluminium composites; Applied sciences; Atomic force microscopy (AFM); Exact sciences and technology; Metals. Metallurgy; Nanoindentation; Nonmetallic coatings; Production techniques; Sol–gel; Surface treatment; Atomic force microscopy (AFM); Aluminium alloy; Sol–gel; Nanoindentation; Aluminium composites; Atomic force microscopy; Multilayer coating; Sol-gel; Multiple layer; Non metal coating; Indentation; Silica; Composite material; Surface treatment; Silicon carbide; Sol gel process; Composite coating
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2006.09.004

Silica coatings up to 20 μm thick have been obtained through a sol–gel route on aluminium matrix composites reinforced with SiC particles. Single silica layer and multiple ones have been deposited on the substrates and extensive crack-free surfaces have been achieved with both methods. The topography of the layers has been characterised by means of Scanning Electronic Microscopy and Atomic Force Microscopy, and dense flat surface has been observed. However, topographical details consisting of spherical zones tend to appear on the surface of multilayered coatings. The mechanical properties of the different coatings have been measured using the nanoindentation technique independently from the substrate underneath, and hardness and elastic modulus similar and even higher than those of fused silica have been obtained for sol–gel multilayered coatings. The microstructure of the coatings has been studied by Transmission Electronic Microscopy, and the appearance of nanocrystals on the flat surfaces has been considered responsible of the mechanical properties measured.