Chemical Vapor Deposition of Aluminum as a Widely Applicable Technique for Corrosion Protection

摘要

Aluminum can be deposited on steel or other metallic substrates by controlled thermal decomposition of aluminum organic compounds at temperatures below 400°C under atmospheric pressure by a technique known as Chemical Vapor Deposition (CVD). Feasibility to use this technique for applications ranging from coil coating to coating of multiple small parts is shown. The morphology and chemical composition of coated substrates were investigated using SEM/EDX method. Characterization of the corrosion resistance of the coating was performed by electrochemical investigations, salt spray and oxidation exposure tests. The resulting Al-layers are closed and show a very even thickness distribution. Such layers provide a better corrosion resistance in neutral media containing chloride ions compared to the widely used Zn-galvanic layers. Hardness and overall corrosion resistance of the aluminum coatings can be even further enhanced by involving other elements like Zn in the coating. By thermal treatment it is possible to transform the pure Al-layers to very stable aluminides with a high-melting point. corrosion protection; aluminum; aluminum-zinc; diffusion layers; chemicalvapor deposition (CVD); atmospheric pressure metal organic CVD (AP MOCVD)