**5. Conclusion**

slight decrease of electrical conductivity can be attributed to the increment of scattering effect. The increase of grain boundaries and the scattering effect of electron wave strengthened by

In order to utilize this novel sol-enhanced technology and promote this technology into real production, the dopant technology has been developed based on the sol-enhanced method. Different types of sol were added into various commercial electrolytes to study their effects on the plating bath and property of coatings. Comprehensive investigations on the technical datasheet for different types of sol are being conducted. Table 2 briefly summarized the different types of sol which can take significant effect on commercial baths according to our studies. It can be seen that this sol dopant technology can be used in almost all types of

**4. Dopant technology derived from sol-enhanced plating and future**

commonly used commercial baths, which gives a broad application prospect.

Types of sol Name of sol Types of commercial bath Inorganic Al2O3 Zn-Ni [26]

Al2O3 Cu

The sol-enhanced coatings have a highly dispersed nano-structure with superior performance. This sol-enhanced technology based on a simple and feasible process which is also compatible with the commercial solution. Therefore, it has great economic potential and market value in the future industrialization. For example, the micro-hardness of sol-enhanced Ni-P and Ni-B coating can reach up to above ~1000 HV, the same level of the widely used hard chrome coatings which require an environmentally harmful fabrication process. Hence, this solenhanced coating technology provides a potential replacement to the hard chrome coatings process [4]. On the other hand, the mechanical property of sol-enhanced Au and Ag coating can be increased up to more than 20% while keep the same level of conductivity and surface gloss. These research outcomes will find wide applications such as jewelry, craftwork and

A combination of different coatings can maximize the performance and functionality of coating by utilizing the different properties of each layer. Recently, we apply multi-layer technology to new sol-enhanced coatings systems in order to optimize the surface properties of coatings [20, 30-31]. Electroless double-layered Ni-P/Ni-P-XZrO2 coatings with different phosphorus

EP means electroless plating, (eg. Ni-B(EP) means electroless Ni-B)

Ni, Ni-P, Ni-B, Ni-Co [27-28], Cu [29], Au, Au-Ni, Ag, Co, Co-W, Sn, Ni-P(EP), Ni-B(EP)[\*]

ZrO2 Ni, Ni-P, Ni-B, Ni-Co, Au, Au-Ni, Au-Co, Ni-P(EP), Ni-B(EP)

the second phase lead to the decrease of electrical conductivity [13].

**industrial application of sol-enhanced coatings**

TiO2

Organic

118 Electrodeposition of Composite Materials

electronics.

Note: [ \*]

**Table 2.** The sols have significant effect on the commercial baths

A novel sol-enhanced method was developed to prepare nano-composite coatings. A small amount of oxide contained sol was added into the traditional electrolyte to in-situ form nanostructured composite coatings with highly dispersed nano-particles. The effect of sol addition on the microstructure and properties of composite coatings has been elaborated. The sol-enhanced nano-composite coatings have much improved mechanical property than that of the traditional coatings without sacrificing corrosion resistance, surface gloss and electrical conductivity. Dopant technology was developed to promote the real application of solenhanced coating method. Multiple sol-enhanced coatings were also developed in order to further improve the property of coatings. Scaling up tests is being conducted in an effort to realize industrial applications.
