Preparation method of anticorrosive composite coating for LNG (liquefied natural gas) gasifier surface

The invention relates to a preparation method of an anticorrosive composite coating for an LNG (liquefied natural gas) gasifier surface. A (Al-Mg)+(Al-Zn) composite coating is prepared on the LNG gasifier surface; the linear expansion coefficient of Mg is between Al and Zn; the formation of the transition layer can obviously improve the bonding strength between the aluminum alloy matrix and the Al-Zn coating; the surface Al-Zn coating has excellent corrosion resistance, and greatly improves the overall corrosion resistance of the LNG gasifier surface coating; even if the surface Al-Zn coating is corroded and perforated, the Al-Mg electrode with lower potential is previously corroded and can still perform the function of protecting the matrix; besides, epoxy resin closing or plastic spraying treatment can be performed on the LNG gasifier surface after spray coating to further enhance the resistance to sea water corrosion; and a surface spray coating technique is utilized to form the gradient coating so as to obtain the ideal composite coating with high bonding strength, surface sea water erosion resistance and uniform corrosion.