Cost-efficient conversion coatings for corrosion protection prepared by the sol-gel process

✍ Scribed by Th. Lampke; S. Darwich; B. Wielage; S. Steinhäuser

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 447 KB
• Volume: 39
• Category: Article
• ISSN: 0933-5137
• DOI: 10.1002/mawe.200800277

✦ Synopsis

Abstract

For several years, chromate compounds were used as effective and inexpensive corrosion inhibitors. Studies showed that these materials were toxic and carcinogenic. A subsequent ban on these materials has led to extensive research to develop effective alternative inhibitors. The sol‐gel method appeared as an effective technique forming protective silane layers from hydrolyzed tetraethylorthosilicate (TEOS) and glycidoxypropyltrimethoxy silane (GPTMS) in an aqueous sol–gel process. The final cross‐linking of the layer is realized by heat treatment to form thin, fully dense, protective films of silane on diverse metal surfaces.

Most sol‐gel layers use a considerable amount of solvent VOC (volatile organic compound) in order to achieve a dispersion of silane with water. However, in a wide range of industries, the high amount of VOC is the major hindrance for the application of silane layers.

This article shows a coating concept without VOC, which is cost‐efficient, effective for corrosion protection and applicable for metal surfaces. The corrosion protection effect is given by means of comprehensive impedance spectroscopy measurements.