Narrow Results

The relative stability of Molybdate-Phosphonic Acid (MPA) Complex in gas phase has been carried out using Density Functional Theory (DFT) methods. The methods used for calculations are B3LYP, BP86 and B3PW91, with three series of basis sets: D95**, 6-31+G (d,p) and 6-31++G (d,p) for hydrogen and oxygen atoms; LANL2DZ for Mo and Phosphorus. Predicted geometry and relative stability are discussed. Equilibrium geometry in the ground electronic state energy has been calculated for 1:1 complex. The best result for energetic and geometrical ground state was obtained with Becke3LYP calculations. The Basis Set Superposition Error (BSSE) begins to converge for all methods/basis sets. For this complex, most levels of theory seem to give reasonable estimates of the known binding energies, but here, too, the BSSE overwhelms the reliability of the binding energies for these basis sets.

The molybdate conversion coating for 6063 aluminum alloy was prepared with Na₂MoO₄·and K₂ZrF₆ via the dip process. The physical and chemical properties of conversion coating were analyzed by CuSO₄ dropping corrosion test, electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM) and energy-dispersive spectrometer (EDS). The optimized process conditions are as follows: Na₂MoO₄·2H₂O 6 g/L, K₂ZrF₆ 3 g/L, pH 3, temperature 40 °C, and reaction time 10 min. The conversion coating exhibits yellow color and consists of Mo, Zr, Mg, Al, O.

Polarization curve test and EIS are used to study the corrosion inhibition effect of silane modification on aluminum alloy (ADC12) in 3% NaCl. The effects of functional group of silane coupling agent, pH, and concentration have been studied. Small and polar group of silane coupling agent is benefit for the protection effect. The optimal conditions of passivation solution are pH of 1.8 and the silane coupling agents concentration of 0.8%.