Preparation And Properties Of Aluminum And Aluminum Alloy Coatings Electrodeposited From Organic Solvent System

Aluminum electrodeposition on Q235 steel from AlCl₃₊LiAlH₄ organic solvent was carried out,and the surface morphology, thickness, structure, adhesion and corrosion resistance of aluminum coating were observed and determined. The results show that the electroplating of aluminum on Q235 steel from AlCl₃₊LiAlH₄ organic solvent is feasible. The deposited aluminum coating is smooth, uniform and with large irregular particle or block forms. The thickness and the particle size of aluminum coating increase obviously with the increase of current density and electroplating time. The adhesion of aluminum coating to the substrate decreases with the coating thickness, and the aluminum coating has a very higher corrosion resistance in 3.5% NaCl solution under the optimum current density of 2⁴ A/dm2 and electroplating time of 30⁶0 minutes. After chemistry conversion, the friction coefficient of the aluminum coating decreases, the microhardness and the corrosion resistance are greatly enhanced.Aluminum-magnesium alloy, aluminum-manganese alloy, aluminum-nickel alloy and aluminum-molybdenum alloy coatings were electrodeposited by adding MgBr₂, MnCl₂, NiCl₂, MoCl₅ into AlCl₃₊LiAlH₄ organic solvent,and the surface morphology, thickness, structure, alloy atom concentration, adhesion and corrosion resistance of aluminum alloy coatings were observed and determined. The results show that the AlCl₃₊LiAlH₄ organic solvent is a valid system for aluminum alloy electrodeposition. The deposited aluminum alloy coatings are flat, smooth, uniform and compact. The thickness of aluminum alloy coatings increases with the increase of current density except aluminum-nickel and the thickness of aluminum-nickel coating increases first and then decreases with the increase of current density. The deposited coating was in a crystalline structure. X-ray diffraction result indicates that the aluminum diffraction peaks were shifted from their standard position to lower angles, which indicates the formation of Al based solid solution. The concentration of alloy atoms increases with the increase of current density except aluminum-molybdenum, and the concentration of molybdenum increases first and then decreases with the increase of current density. The adhesion of aluminum alloy coating with the substrate is greater than 50 N. The aluminum alloy coatings can be arranged as follows:...