Setareh Golrooh - MS student
Saeed Reza Allahkaram - Assosiate professor, School of metallurgy and materials engineering
Morteza Mohammadalipour - MS student

Composite coating electroplating nano-sized particles is promising candidates for advanced surface finishing applications. The inclusion of hard particles such as alumina in a metal matrix can yield high mechanical properties. The presences of fine dispersion of Al2O3 particles in a copper matrix improve the hardness and corrosion resistance. In addition, high thermal stability of Al2O3 particles prevents the particles from ripening and dissolving which thus retain their ability to obstruct dislocation motion and slow down the rate of grain growth at temperatures even close to the melting point of copper matrix where other reinforcing mechanisms such as precipitation hardening or solid solution strengthening rapidly lose their effectiveness. However, just putting the particles in a commercial plating bath and electroplating with the standard parameters usually does not work. It is generally accepted that the characteristics of the metal deposition process and the conditions in the cell are important parameters in coating process. In this investigation copper matrix was reinforced with nano Al2O3 particles by both DC and Pc methods in order to compare the properties of composite and non composite coatings applied by both methods. Because of the very fine grain sizes, composite coatings exhibit a variety of properties that are different and considerably improved in comparison with its matrix and also non composite copper coating. These include morphological/structural properties, increased hardness and enhanced corrosion resistance. The combination of increased hardness/corrosion resistance results in improved protective coating performance that can be used as a hard surface on softer substrates.

Pulse plating, Electrocodeposition, Composite coating, Nano particle, alumina