**3. The applications of ceramics coated metallic materials**

Up to now, the ceramics coated metallic materials have great potential in a wide variety of applications due to its unusual properties, such as good mechanical properties, corrosion resistance, thermal stability, and biological properties. It is worth noted that hydrophobic treatment of ceramic coatings on metallic materials ensuring superhydrophobic surfaces with special surface physicochemistry has recently received much attention in many fields.

It is well known that metallic material is irreplaceable in industrial application. The ceramic coatings bestow numerous unusual properties to metallic materials. Early in 1987, Ceramic coating as thermal barrier coating was tested on turbine blades in a research engine. Today, thermal barrier ceramic coatings are used in a low risk location within the turbine section of certain gas turbine engines [11]. In addition, Qin *et al.* reported that multiphase ceramic coatings significantly improved the hardness and wear resistance properties of 5052 Al alloy, which is conducive to industrial application [61]. In 2018, an alumina-titania ceramic coating was fabricated on carbon steel for corrosion protection [62].

Recently, superhydrophobic surface has been extensively developed due to its unique property including corrosion protection, self-cleaning, oil water separation, anti-fouling, anti-icing, and drag reduction [63]. Superhydrophobic ceramic coating was obtained by hydrophobic treatment of ceramic coating with hierarchical rough structure, which greatly expanded the application range of metal materials [64, 65]. In 2020, Emarati *et al.* fabricated a superhydrophobic nano-TiO2/TMPSi ceramic composite coating on 316 L steel by using a one-step electrophoretic deposition method, the results indicated that the superhydrophobic ceramic nanocomposite coating had excellent corrosion resistance [66]. Also, the water shear stress and drag can be reduced on superhydrophobic ceramic coated metallic materials surfaces resulting from the air pockets present between the liquid and solid substrate. In this context, the rolling-off droplets can remove contamination particles displaying self-cleaning feature [22]. Furthermore, a superhydrophobic ceramic coating is also reported as an emerging material exhibiting their promising diverse applications for anti-fogging, anti-fouling, and oil water separation [67–69]. **Figure 2** shows the oil/water separation of *1H, 1H, 2H, 2H*-perfluorodecyltriethoxysilane-modified CuO-grown copper foam (PCCF).

### **Figure 2.**

*Separation apparatus with an 18:25 v:v isooctane/water mixture above PCCF. Inset, PCCF was fixed in Cu flange and then sandwiched between two glass tubes (a). Isooctane passed through PCCF whereas water was retained (b). Water is dyed blue. Scale bar, 3 cm. Reproduced with permission [69]. Copyright 2013, Royal Society of Chemistry.*

In addition, ceramic coatings have numerous applications in the field of biomedical engineering, mainly because of their biological properties. The bioinert properties of ceramic coatings help them with biocompatibility, and good hardness and wear-resistance properties make them suitable for substitution of hard tissues (bones and teeth). On the contrary, bioactive ceramic coatings such as HA coating have been clinically used onto the metallic implant surfaces combining the mechanical strength of metals and their alloys with the excellent biological properties of ceramics for the enhancement of new bone osteogenesis [70, 71].

Importantly, researching work shows that superhydrophobic surfaces can dramatically reduce the contact between fouling organisms and substrate surfaces

### **Figure 3.**

*The comparison of properties of unmodified ceramic coating and superhydrophobic ceramic coating on metallic materials.*

*Ceramics Coated Metallic Materials: Methods, Properties and Applications DOI: http://dx.doi.org/10.5772/intechopen.93814*

exhibiting excellent anti-fouling and hemocompatibility properties [72, 73]. Hu *et al.* designed a superhydrophobic SiO2 biodegradable coating with exceptional anti-bioadhesion through one-step co-electrospraying poly(L-lactide) (PLLA) modified with silica nanoparticles [74]. It was revealed that the superhemophobic TiO2 surface with a robust Cassie–Baxter state displayed more hemocompatible compared to hemophobic or hemophilic TiO2 surface [75]. The comparison of properties of unmodified ceramic coating and superhydrophobic ceramic coating on metallic materials is shown in **Figure 3**.
