**1. Introduction**

In most cases, materials have a limited lifetime, which strongly depends on the actions of external factors and the operating environment. Occasionally, chemical or electrochemical

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reactions with the environment take place, which will sooner or later damage functionality by attacking the surface. Because of the atomic structure, the surface of a material or a component is the most vulnerable site for various forms of attacks and, therefore; it might be deemed. These attacks could be present individually or in combination of mechanical, chemical, electrochemical or thermal in nature [1]. The coating processes which maximize the lifetime of the materials can be classified as evaporation, hot metal processes, painting, thermal spraying, and **metallising**. Metallising appears to have particular importance in these main coating processes compared to others. Metallising is devided in two sub-groups, such as **electroless metal coating**, and **electrolytic metal coating**.

Among the processes concerning the production of nanostructured composites, the electro‐ deposition technique has further demonstrated the following benefits: a smoother surface, a better bonding between particles and a metal, an easier control of the thickness of the coating, appropriacy to automation, availability for obtaining metallic alloys and composite coatings, and, finally, a possibility to achieve higher microhardness [2].

It is known that combining the best properties of different materials to obtain one material with excellent properties is the main idea of fabricating composites. **Electrolytic co-deposition technique** seems to be feasible based on the idea determined.

In the present chapter, entitled **A New Approach: In-situ Codeposition of Composite Coatings,** general information about electrolytic coating and electrolytic codeposition is given and the factors affecting the coating structure, the main layer-property relations are explained in details. The electrolytic codeposition section explains the parameters, such as pH, zeta potential, agitation and etc., affecting this process. Under the section 3, property-performance relations of these coatings are examined. Finally, **in-situ codeposition** is detailed with examples and the experimental findings of our and other research groups are presented.
