Research On High-intensity Ultrasonic Fabrication And Corrosive Resistance Of Nano-CeO_2p/Galfan Metal Matrix Composites

The composites of Galfan alloys reinforced by nano-CeO2 featured with good corrosion resistance, adhesion and excellent processing performance, can be used as protective materials for steel components. In present study, surface pretreatment to nano-CeO2 particulates (average particle diameter 25nm), fabrication process of nano-CeO2/Galfan (ZACs) with different CeO2 contents via high-energy ultrasonic stirring technique, the wetting process between particles and molten Galfan alloy, the mechanical properties, the corrosion resistance and corrosion mechanism of ZACs were investigated using more than one means.The TEM and AES et al results indicate that the distribution of nano-particles is obviously improved and the surface covering thickness is about 20nm. The carbonization temperature range of covering layer on nano-CeO2 particle is 300～500℃. According to thermodynamic analysis, the wettability of the ZACs system could be improved due to the reaction between the carbonized surfactant on nano-CeO2 surface and the block of zinc oxide film on the surface of Galfan melt.Based on the FE-SEM observations, the dispersion of untreated nano-CeO2 particles into Galfan alloy melt is quite difficult. And the pretreated nano-CeO2 particles could distribute homogeneously into the alloy matrix when the mass fracture is below 3.0wt.%, but the excessive loading also results in the agglomeration. The microstructure observations also show that the finest distance of lamellar body of matrix alloy could be achieved at a 1.0wt.% nano-CeO2 particles. The apparent viscosity of composites is remarkably influenced by the addition of nano-particles according to the height decreasing rate of composite before and after re-melting.A optimized amount of CeO2 addition could improve the mechanical properties Galfan matrix. The peak values of HV hardness, modulus and tensile strength are increased by 41.2%, 34.6% and 34.2% compared to original Galfan alloy, however, the elongation ratio of composites decreases by 4.6%. But the increased mass fraction deteriorates the distribution of CeO2 particles in matrix alloy, which leads to the decrease of mechanical properties of ZACs. The tensile fracture also shows that the damage mechanism of composites varied into a brittle fracture pattern.The results of various corrosion tests indicate that the corrosion resistance of the composites increase initially and then decrease with the increasing nano-CeO2 content. The best electrochemistry and salt spray corrosion resistance were achieved at the 1.0wt.% particles and the peak value of intergranular corrosion resistance was obtained at 0.8wt.% nano-CeO2 addition. The addition of nano-CeO2 enhances self corrosion potential, therefore enhances the corrosion resistance of the ZACs.