The effect of grain size on the wear properties of electrodeposited nanocrystalline nickel coatings

Abstract

Department of Metallurgy and Materials Science, University of Toronto, 184 College Street,Toronto, Ontario, Canada M5S 3E4*Integran Technologies Inc., 1 Meridian Road, Toronto, Ontario, Canada M9W 4Z6(Received August 25, 2000)(Accepted September 13, 2000)Keywords: Nanocrystalline nickel; Wear; Electroplating; Grain boundariesIntroductionNanocrystalline materials, as a result of the considerable reduction of grain size and their significantvolume fraction of grain boundaries and triple junctions, have exhibited many unusual mechanical,physical, chemical and electrochemical properties compared with conventional polycrystalline oramorphous materials [e.g. 1,2]. For many engineering applications, wear resistance is one of the mostimportant mechanical properties because wear accounts for more than 50% loss of all materials inservice [3]. Grain size reduction has been previously shown to lead to significant improvements of thewear resistance in nanocrystalline materials. For the case of nanostructured WC-Co composites, forexample, the reduction of WC grain size to 70 nm nearly doubled the abrasive wear resistance overconventional cermets [4]. Nanocrystalline nickel with 10 ; 20 nm grain size made by electrodepositionshowed 100 ; 170 times higher wear resistance and 45 ; 50% lower friction coefficient thanpolycrystalline nickel with 10 ; 100 mm grain size in the pin-on-disk test [5]. When the grain size ofaluminum was reduced from 1 mm to 16 nm, the peak coefficient of friction decreased by 57% in theminiature pin-on-disk test [6].In this study, the effect of grain size reduction on the wear resistance of electrodeposited nanoc-rystalline pure nickel coatings was investigated quantitatively by the Taber abrasive wear test, astandard test often applied in industrial testing.ExperimentalThe substrates for nanocrystalline nickel coatings were AISI 1010 mild steel with a size of 10 3 10 cm