Alternatives to cadmium plating on fasteners have been evaluated for a number of years. Torque-tension and corrosion resistance characteristics have been the major concerns. Zinc plating has been a popular substitute, but torque-tension at proper preloads on Grade 8 fasteners requires more torque. Torque-tension tests were ALSO evaluated on Grade 5 fasteners - same coatings.
A previous paper presented by the authors at SSPC 2015 demonstrated the futility and folly of attempting to use accelerated corrosion testing as a tool for predicting real world corrosion performance. The effect of corrosion was shown to be governed by the type of ions and the concentration of oxygen in the corrosion environment. By understanding these two factors, accelerated corrosion testing can, however, be used as an indicator of performance which may be encountered in the real world.
Cavitation erosion of the rudder has been a serious problem in the high-speed container ship industry. It is well known that the lifetime of a conventional coating system is about 6 months against cavitation bubble collapse. Although STS 316L stainless steel has been applied to prevent such a problem, there are several drawbacks such as high repair cost and poor workability.
When coatings are applied to substrates as e.g., metal, the adhesion of the cured paint is a critical parameter for the final performance of the paint film. The adhesion of the paint to the substrate influences many properties of the paint, which including visual appearance, anticorrosive performance, flexibility, resistance against scribing and scratching, delamination, blistering and many more. Many actions can be taken to influence and improve the adhesion of a coating to a substrate.