Effect Of Current Density And Heat Treatment On The Characteristic, Wear Resistance And Adhesion Of Nickel Nanocrystalline Coatings Deposited On Aluminum Alloy 7075 Substrate

The nickel-fly ash (Ni-FA) composite coatings were deposited on zincated aluminium alloy 7075 (AA7075) 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.