Electrochimica Acta 50 (2005) 4551–4556 Corrosion and wear resistant electrodeposited composite coatings Maria Lekka a , Niki Kouloumbi a,∗ , Mauro Gajo b , Pier Luigi Bonora c a National Technical University of Athens, 9 Heroon Politechniou Street, 15780 Athens, Greece b Elsy Rersearch snc, Conegliano, TV, Italy c University of Trento, Italy Received 27 January 2004; received in revised form 18 October 2004; accepted 18 November 2004 Available online 24 June 2005 Abstract Composite electroplating is a method allowing to co-deposit fine particles of metallic or non metallic compounds into the plated layers in order to improve the surface properties. The aim of the present work was to compare the performance of pure nickel and Ni–SiC nano-structured composite coatings as far as corrosion, wear and abrasion resistance were concerned. The characteristics of the coatings were assessed by scanning electron microscopy, micro hardness test, Taber Abrader test, electrochemical impedance spectroscopy and wear corrosion measurements. Additionally accelerated salt spray tests were performed. The results obtained in this study indicate that the co-deposition of nickel and SiC nano-particles leads to uniform deposits possessing better abrasion, wear and corrosion properties. © 2005 Elsevier Ltd. All rights reserved. Keywords: Nickel; Silicon carbide; Nano-particles; Composite; Coating; Abrasion; Corrosion 1. Introduction The need for coatings with improved resistance to highly aggressive environments is high as a result of a growing demand for extended safe service life of industrial objects. In our previous research work the corrosion and wear corro- sion resistance of nitrides coatings [1], (TiCr)N and Ti/TiN PVD coatings [2], hard chromium coatings[3], HVOF cermet coatings[4] as well as of composite electrodeposited coatings of nickel and nano-crystals of silicon carbide was studied [5,6]. The production of nano-composite films can be achieved through electrochemical deposition of the matrix material from a solution containing suspended particles such as: oxides, carbides, nitrides, metal powder and s.a. This tech- nique has been applied in the present work using nanometer size SiC particles for the production of the composite coat- ings. Ni–SiC composites have been studied extensively [7–10] and commercialized successfully for the protection of ∗ Corresponding author. Tel.: +30 210 7723101; fax: +30 210 8035906. E-mail address: koni@chemeng.ntua.gr (N. Kouloumbi). mechanical parts under friction, due to their high wear resis- tance and the low cost of ceramic powder. The usual dimen- sions of SiC powder in such applications are in the range of micrometers. The shapes used vary from round to acicu- lar while a mixture of them can also be used. The objective of the present experimental work is the extension of these researches when nano-crystals of silicon carbide (mean diam- eter 20 nm) are codeposited. 2. Experimental Two types of samples were prepared. Samples coated with pure nickel coating and samples coated with Ni + SiC coating. The electroplating bath used for the electrochemical depo- sition of pure nickel coatings had the following composi- tion: 240 g/l nickel sulphate (NiSO 4 ), 45 g/l nickel chloride (NiCl 2 ), 30 g/l boric acid (H 3 BO 3 ) and 10 g/l sodium dode- cylsulphate (CH 3 (CH 2 ) 11 OSO 3 Na). The pH of the solution was about 4.5. The nanostructured SiC-nickel coatings were electrode- posited from a suspension of SiC nanoparticles (20 nm) in the above mentioned electrolyte. Suspensions were pre- 0013-4686/$ – see front matter © 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.electacta.2004.11.067