Microstructure And Properties Of Aluminum And Aluminum Based Alloy Films Prepared By Evaporation And Magnetron Sputtering

Aluminum and aluminum alloy films were deposited onto Q235 steel by evaporation and DC magnetron sputtering. The surface morphology, microstructure, thickness, adhesion and corrosion resistance were studied. The effect of different treatments on the properties of films was also investigated.The results show that aluminum films could be deposited onto Q235 steel by evaporation and DC magnetron sputtering methods. Effective pretreatment could improve the quality of aluminum film, which helpful to obtain uniform, fine-grained morphology and excellent corrosion resistance. The aluminum film deposited by vacuum evaporation is in irregularly netlike form. With the increase of thickness and evaporation rate, aluminum film becomes smooth, flat and uniform. The adhesion force between the aluminum film and the substrate is entirely larger than 60N. The results of corrosion tests in 3.5% NaCl solution showed that the polarization resistance of Al films are larger than 4000?·cm2, while the substrate is only 1000?·cm2. Pure aluminum film can provide the substrate a well-protected effect.In order to improve the properties of aluminum film, the annealing treatment was carried out. It was seen that the lattice parameters of annealed aluminum films were diminished. The corrosion resistance of Al film after annealing with the thickness less than 0.8μm is less than that of as-deposited film, while the corrosion resistance of 1.0μm Al film is enhanced after annealing. The adhesion force of annealed Al film is a little smaller than as-deposited film.Compared with pure aluminum, it was found that the aluminum diffraction peaks of aluminum-manganese alloy film are shifted from their standard position to higher angles in X-ray diffraction curves. The polarization resistance of aluminum-manganese alloy film is about 5.0×104?·cm2, which is nearly five times as great as pure aluminum film. After the addition of Mn, the adhesion force of Al-Mn film decreases slightly.Aluminum film deposited by DC magnetron sputtering is smooth, uniform, and compact and with a spheroid particles. Under the same film thickness, the corrosion resistance of magnetron sputtering aluminum film is better than evaporated aluminum film. The polarization resistance could reach to 3.7×104?·cm2, which could protect the substrate well. At the meantime, the adhesion force is entirely beyond 64N, better than aluminum film obtained by evaporation.The morphology of Aluminum-magnesium alloy films is also smooth, uniform and compact with spheroid particles. The particle sizes and the content of magnesium in Al-Mg alloy films grow gradually with the increase of current and thickness. The optimum current for aluminum-magnesium alloy films is 0.1A. The corrosion resistance of Al-Mg film increases firstly, and then decreased with the increase of current. With the increase of the thickness, the Al-Mg film provided a higher corrosion resistance.