Application Status and Corresponding Protection Technology of Titanium Alloy in Marine Environment

Titanium and titanium alloy have an excellent corrosion resistance in seawater and marine atmosphere, and have been widely applied in ships, submarines, deep submersibles, oil and gas exploration and seawater desalination devices. However, the titanium has some disadvantages of poor wear resistance, proneness to biofouling and severe contact galvanic corrosion during service in the harsh marine environment with high temperature, high humidity and high salinity. These disadvantages restrict the long service life, safety and reliability of titanium structural parts. The application status of titanium in marine environment is reviewed and the natural reason for the above problems is revealed. The interaction of wear and corrosion in marine environment leads to the increase of the material loss of titanium with poor wear resistance. The good biocompatibility of titanium causes serious biological fouling. Compared with other metals, titanium has a high positive potential, which makes it to be protected as a cathode when coupled with other metals in the medium environment, thus accelerating the corrosion of the coupling alloy. The application of titanium in marine environment will be wider and the appropriate surface treatment and coating protection are essential to solve the above problems of the poor tribocorrosion resistance, serious biological fouling and galvanic corrosion for the titanium used in marine environment. The research status of protection technology to solve the above problems of titanium used in the marine environment is reviewed. The ceramic coating and controllable nanostructure oxide ceramic coating are the promising methods for tribocorrosion protection of titanium moving parts in marine environment. The antifouling agent release and nano slow release coatings are the promising technologies to achieve long-term biological fouling prevention of titanium. The design and preparation of the surface modification layer with the low conductivity on titanium surface can reduce the galvanic corrosion rate of the other metals in contact with titanium. The development trend is prospected for the surface protection technology on titanium in marine environment. The design and development of the technologies and equipment suitable for titanium surface treatment, such as the high temperature nitriding equipment and technology for titanium, and the deformation of complex titanium components with large size and thin walls caused by high-temperature nitriding also need to be focused on and resolved. For the nitride and oxide coatings with excellent tribocorrosion resistance, the design and preparation should focus on the development of multi-component, multi-scale structure coordination, surface and interface structure optimization, and achieve multi-functional integration and environmental adaptability. The anti galvanic corrosion technology in new electromagnetic field has a good application prospect. The research on the effect of magnetic field strength and magnetic field orientation on galvanic corrosion protection and the design of new magnetic field protection devices are expected to achieve long-term, safe and reliable service of titanium and other metal coupling equipment structures. It is urgent to carry out research on the establishment of damage evaluation device, evaluation method and damage mechanism of titanium materials under extreme environment, complex working conditions and strong coupling of multiple factors. It is an inevitable trend to develop the composite technologies of the multiple surface treatment for titanium parts used in extreme environments. © 2023 Chongqing Wujiu Periodicals Press. All rights reserved.