Surface Modification Of Floating Beads And Preparation Of Floating Beads Reinforced Composite Coating

Floating beads are a kind of cenospheres which are fine, weight light and acid alkiaresistance. Besides, it also has the characteristics of heat resistance, insulation, chemicalstability, non-toxicity and refractory. It is a by product of burning coal. Its density is0.3g/cm3, it can drift on water surface. Therefore, it is not fit to act as reinforce particles appliedin composite plating field.Firstly, the surface of floating bead was modified in a solution containing titaniumsulfate by heterogeneous deposition method in order to increase the density of floating beads.And then the modified floating beads were used as reinforced particles, and Ni-P/floatingbeads composite coating were prepared by composite electroplating method. Themicrostructure of modified floating beads, and microstructure, interfacial adhesion andcorrosion resistance of the composite coatings were investigated by optical microscope,SEM, EDS, XRD, and friction and wear tester, and electrochemical work. The experimentalresults were obtained as follows.A TiO2film was prepared on the surface of floating bead. When the Ti(SO4)2contentincreases, the theoretical coating thickness increases. When the theoretical coating thicknessis over0.3μm, the crack appears on the surfaces of floating beads. When the pH valueincreases, the compactness of the TiO2film first increases and then decreases. Along withthe analysis results of EDS, we think the best preparation process of TiO2film is pH5. Whenthe reaction temperature increases, the deposition rate of TiO2increases, the best reactiontemperature is50℃. Above at all, the best preparation process of TiO2film covering floatingbeads is theoretical coating thickness of0.3μm, the reaction temperature of50℃and pH5.Ni-P/floating beads composite coatings were prepared by composite electroplatingmethod. When the addition of modified floating beads in the solution increases, the contentof modified floating beads in the composite coating also increases. For the composite coating produced in the addition of modified floating beads of15g/L, the content of floating beads inthe coating is less and its coating thickness is thinner. It is found that the bigger is the currentdensity, the thicker is the coating thickness and the finer is the particles of the coating. Thebest preparation process is the addition of modified floating beads of10g/L and currentdensity of20mA/cm2.The Ni-P/floating beads composite coatings were prepared on the surface of aluminumalloy. The results show that the interfacial adhesion of composite coating is biggest when theaddition of modified floating beads is10g/L and the current density is20mA/cm2.The corrosion resistance of the Ni-P/floating beads composite coatings wereinvestigated in3.5%NaCl aqueous solution. The results show that the corrosion resistance isbest for the coating prepared in the condition of modified floating bead addition of10g/L andcurrent density of20mA/cm2.