## 1 Introduction
[PERSON] coated nanocomposites on 304 stainless steel substrates based on dip-coating method in thin-film technology and successfully prepared nano-TiO\({}_{2}\) composite coatings with good corrosion resistance through corrosion resistance and stability tests [35]. [PERSON] successfully prepared low coating damage and high corrosion resistance nano-TiO\({}_{2}\) coatings on MS mild steel by using the doctor blade coating method, which enhanced the structural and morphological properties and corrosion resistance of mild steel (MS) plates [36]. In the TiO\({}_{2}\) and Al\({}_{2}\)O\({}_{3}\) composite coating system, TiO\({}_{2}\), which has a lower melting point, is able to improve the toughness of the composite coating and enhance the bonding force between Al\({}_{2}\)O\({}_{3}\) grains [37; 38]. By optimizing the ratio of TiO\({}_{2}\) to Al\({}_{2}\)O\({}_{3}\) powder, TiO\({}_{2}\)-Al\({}_{2}\)O\({}_{3}\) composite oxide powders with different properties can be prepared [39]. [PERSON] investigated the microstructure and wear properties of Al\({}_{2}\)O\({}_{3}\)-13 wt% TiO\({}_{2}\) coatings prepared by plasma spraying agglomerated nanoparticle powders, and found that the microhardness of the nanostructured coatings was about 15%-30% higher than that of the conventional coatings, with a significant increase in wear resistance [40]. [PERSON] used plasma spraying technique to prepare Al\({}_{2}\)O\({}_{3}\)-TiO\({}_{2}\) nanocoatings, and four nanostructured Al\({}_{2}\)O\({}_{3}\)-13 wt% TiO\({}_{2}\) coatings were prepared by varying the plasma spraying parameters, and the wear test results showed that the nanostructured coatings were three to four times more wear-resistant than the conventional coatings [41]. Current research shows that the proportion of TiO\({}_{2}\) is usually less than 30 wt%, and the content of more than 50 wt% is rarely studied, and Al\({}_{2}\)O\({}_{3}\) as the backbone of the wear-resistant phase can significantly improve the hardness of the coating through the grain refinement and dispersion reinforcement and the formation of a continuous corundum network to give the system a high load-bearing capacity [42]. However, the high content of Al\({}_{2}\)O\({}_{3}\) is prone to cause interfacial stress concentration leading to the increase of wear rate, and there is a risk of grain boundary embrittlement of pure Al\({}_{2}\)O\({}_{3}\) in high-temperature oxidizing environment at 400-500 \({}^{\circ}\)C. Existing researches are mostly focused on the Al\({}_{2}\)O\({}_{3}\)-phosphoric acid system (through the formation of AlPO\({}_{4}\) network to realize the low-temperature densification), and the mechanism of synergism of multicomponents has not been explored sufficiently. In this study, a synergistic strengthening scheme of nano-TiO\({}_{2}\)-coated Al\({}_{2}\)O\({}_{3}\) is proposed to design a core-shell structure of 65 wt% nano-TiO\({}_{2}\)-coated 30 wt% micrometer Al\({}_{2}\)O\({}_{3}\), which maintains a high level of corrosion resistance while forming a submicrometer reinforcement network through interfacial metallurgical bonding. This system has a broad application potential in the field of aerospace high-temperature parts protection, marine equipment corrosion-resistant coatings and heavy machinery wear-resistant linings, especially suitable for high-temperature working conditions under the environment of high load-bearing components of the surface reinforcement, for the performance of multi-component ceramic coatings synergistic design to provide a new paradigm.