P 410 - Production of a fuel tank of complex geometry from steel using hydroforming

P 411: Basic properties and potential of decorative glassy sol-gel coatings on stainless steel for industrial applications Stainless steels, commonly referred to as stainless steels, are often used for decorative purposes in the household and architectural sectors. Depending on the application and stress, an attractive appearance can only be achieved in the long term if measures are taken to prevent scratching in daily use and discolouration under thermal stress. The aim of the research project was to investigate the basic properties and potential of decorative glass-like sol-gel coatings as a transparent alternative to enamel coatings with corresponding properties. As part of the present work, a glass-like sol-gel coating system already developed by the Institute for New Materials (INM) was tested for the requirements of the industrial partners involved in the project. In particular, the extent to which these requirements can be met with continuous or piece coating and the extent to which the system can be formed, welded or mechanically joined was investigated. Parallel to the tests at the industrial partners, investigations were carried out at the INM to optimise the existing system (particle incorporation, component variations) and to combine several coating systems (primer layer plus metal oxides). The results of the investigations have shown that the properties of stainless steel surfaces can be significantly improved in some areas by applying the glass-like coatings. The coatings can achieve at least temporary (approx. 500 h) tarnish protection at 500 °C. The abrasion resistance of the stainless steel surface is significantly improved. After 500 cycles of the abrasion test, there are only isolated scratches, whereas uncoated steel is already severely damaged after 10 cycles. Furthermore, in the area of high-temperature protection, it was demonstrated that the investigated glass-like coatings offer a clear advantage over conventional sealing methods when it comes to maintaining the visual appearance of stainless steel. However, tests with mechanical stresses have also shown that the glass-like coatings do not offer sufficient elasticity for any necessary forming operations. forming operations. In the case of piece coatings, on the other hand, glass-like sol-gel coatings can offer advantages depending on the requirements profile. This applies to scratch resistance, tarnish protection and transparency of the coating as well as easier cleaning. Colouring without major impairment of the metallic appearance is also conceivable. However, significant optimisation steps are still required to exploit this potential in the household and office furniture sector, in the automotive and architectural sectors and for decorative purposes. STUDIENGESELLSCHAFT STAHLANWENDUNG e.V. Publication: 2001 Authors: Dr rer. nat. M. Amlung, Dr.-Ing. K. Endres, Dipl.-Chem. Ch. Schelle