Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 50, Issue 1 (2018) 1-9 1 Penerbit Akademia Baru Journal of Advanced Research in Fluid Mechanics and Thermal Sciences Journal homepage: www.akademiabaru.com/arfmts.html ISSN: 2289-7879 Effect of Current Density and Fly Ash Composition on Nickel Grain Size and Hardness of Nickel-Fly Ash Composite Coating Deposited on Aluminum Alloy 6061 Intan Sharhida Othman 1,∗ , Muhamad Khaizaki Ahmad 1 , Muhammad Zaimi Zainal Abidin 1 , Qumrul Ahsan 1 , Noraiham Mohamad 1 , Syahrul Azwan Sundi 2 1 Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia 2 Faculty of Engineering Technology, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia ARTICLE INFO ABSTRACT Article history: Received 3 May 2018 Received in revised form 19 August 2018 Accepted 22 September 2018 Available online 26 September 2018 The nickel- fly ash (Ni-FA) composite coatings were deposited on zincated aluminium alloy 6061 (AA6061) substrate by using electrodeposition technique. The electrodeposition process was carried out for 1 hour at 40º C. The current density used was extended from 1, 5 to 9 A/dm2. Fly ash particles was added to nickel citrate bath at 0, 10, 50 and 90 g/l for electrodeposition of Ni-FA composite coating. The produced composite coatings were characterized using X-ray Fluorescence (XRF) and X-ray Diffraction (XRD). Microhardness of Ni-FA composite coatings were also investigated in this study. As the current density increased from 5 to 9 A/dm2. The nickel grain size in the Ni-FA composite coating were decreased. The decreasing in nickel grain size resulted in increasing of hardness value. Besides, the hardness results show a clear increasing trend with an increase of fly ash composition from 10 to 90 g/l, due to the presence of hard oxide in the fly ash particles. Keywords: Current Density, fly ash composition, grain size, Ni-FA composite coating Copyright © 2018 PENERBIT AKADEMIA BARU - All rights reserved 1. Introduction Aluminium alloy 6061 (AA6061) is the most versatile of the heat treatable alloy which is commonly used for medium to high strength requirements and has good toughness characteristics. Based on Leon [1], the aluminium alloy 6061 has excellent strength to weight ratio, corrosion resistance, good ductility and cracking resistance in adverse environment. These AA6061 is extensively employed in marine frames, pipelines, storage tanks, automotive parts and aircraft application [2]. However, according to Bocking and Reynolds [3] and Visser [4], it has low hardness and wears resistance, as well as susceptible to surface degradation when exposed to elevated temperatures. Therefore, nickel composite coating is introduced to AA6061 to improve its properties. According to Nguyen et al., [5], the composite coating is a helpful and minimal effort approach to ∗ Corresponding author. E-mail address: intan_sharhida@utem.edu.my (Intan Sharhida Othman) Open Access