With the development of the city, more and more cities are building rail transit, such as subway, urban rail, high-speed rail, etc. in the process of building rail transit, coating process has been an indispensable link, which greatly improves the service life and shelf life of rail transit vehicles, protects objects for a long time, prevents chemical corrosion, climate impact, chemical impact, etc. For example, in the case of acid rain, high temperature exposure and large temperature difference, they all play a very good role in protection.