Investigation on electroless Cu–P–micro/ nanoSiC composite coatings S. Faraji* 1 , A. H. Faraji 2 , S. R. Noori 3 and F. N. Ani 1 Copper–phosphorus (Cu–P) coatings composited with superfine silicon carbide (SiC) particles were prepared by electroless plating. The composition, morphology, structure and roughness of the composite coatings, with micro- and nanosize SiC particles were studied respectively by energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and atomic force microscopy (AFM). It was shown that SiC particles are codeposited homogeneously and Cu–P–SiC composite coatings have crystalline structure. Mechanical properties of coatings were studied by Vickers hardness and wear testers. Cu–P/nano–SiC composite coating showed higher microhardness and better antiwear performance than microsize SiC composite coatings. Corrosion resistance of the electroless Cu–P composite coatings on carbon steel was studied in 3?5 wt-% NaCl and 1M HCl solutions by potentiodynamic polarisation technique. The study revealed that the corrosion resistance increases with incorporation of nano SiC particles in the Cu–P. Keywords: Electroless Cu, Micro/nanoSiC, Corrosion, Hardness, Wear This paper is part of a special issue on electrodeposition Introduction In the past few decades, a lot of research has been carried out on electroless plating of Ni 1–9 and Cu, 10–13 both on the particles and on the substrates. Diversified metallic and non-metallic surfaces endowed with attrac- tive appearance, high corrosion resistance, electromag- netism, low density and some other special properties were produced by electroless copper. Because of excellent thermal conductivity, the electroless copper technique has been widely used in electronic industry, machinery manufacturing and national aerospace plane airframe. Owing to high mechanical strength and electrical conductivity, copper matrix composites have a wide range of applications as electrical material for conductive fabrics, lead wires, relay blades, contact supports and electrodes for spot welding. The extensive demand for these applications promotes the development of copper formulation and plating techniques. 10–12,14–16 Embedding particles in electroless deposited metals is a convenient method of preparing composite coatings, in which the particles increase the mechanical and physical properties. 7 With the addition of SiC to the coating, 3,17–21 Si 3 N 4 , 22–24 Al 2 O 3 , 3,5,25,26 ZrO 4 , 27 B 4 C, 28,29 WC 30,31 and TiO 2 9,32,33 particles, corrosion and wear resistance of composite coatings is extremely improved. SiC is a useful electronic material, which is a high strength ceramic with excellent corrosion and erosion resistance. Thus, electro- less metal–P–SiC composite coatings are attractive and have been investigated before. 18–20 Among the solid particles used as reinforcement, SiC is studied and applied more frequently. Because of their high strength, excellent corrosion and erosion resistance, thermal conductivity and mechanical and physical properties, 18–20,34 SiC particles are of great technological importance for their applications as semiconductor materials and structural ceramics. In recent years, SiC has found new applications in electronic industry for its excellent and adjustable dielectric properties. 35 With the electroless plating process, solid SiC particles used for reinforcement are added to the plating solution and are stirred to avoid sedimentation of particles in the solution so that codeposition of the discrete SiC particles can be obtained. 34 Consequently, corrosion resistance, microhardness and wear resistance of composite coatings are greatly improved with incor- poration of SiC particles. Recently, Faraji et al. 20,36–40 reported that corrosion and erosion resistance of electro- less Cu–P increased with the addition of SiC particles. Some authors have reported that smaller particles with a narrow size distribution yielded the excellent chemical and mechanical properties under the similar operating conditions. 5,41 Moreover, development of nanotechnol- ogy has raised interest in metal matrix nanocomposite coatings because of their unique chemical, mechanical, magnetic and optical properties. 9,16,40 Carbon steel is one of the major construction materials used extensively in chemical and allied indus- tries dealing with acidic, alkaline and salt solutions. The corrosion of carbon steel is a major infrastructure 1 Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor D.T., Malaysia 2 Young Researchers Club, Varamin-Pishva Branch, Islamic Azad University, Varamin, Iran 3 Department of Material Science and Metallurgical Engineering, Iran University of Science and Technology, Tehran, Iran *Corresponding author, email soheilafaraji@yahoo.com ß 2015 Institute of Materials, Minerals and Mining Published by Maney on behalf of the Institute Received 21 February 2014; accepted 13 July 2014 DOI 10.1179/1743294414Y.0000000334 Surface Engineering 2015 VOL 31 NO 3 179