Characterization and electrochemical corrosion properties of Sn and Al + Sn containing coatings on magnesium alloys prepared by laser surface treatment

Abstract

Sn and Al þ Sn containing coatings were prepared on the surface of AZ91D magnesium alloy by laser surface treatment. The microstructure and composition of specimens were analyzed by metallurgical microscope, scanning electron microscope (SEM), field emission scanning electron microscope (FESEM) equipped with energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The corrosion resistance of the as-received and laser treated magnesium alloys were evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests. The effect of Sn and Al þ Sn addition on the microstructure, composition and corrosion behavior of magnesium alloys was investigated. Results showed that the surface presents different phase composition. The corrosion resistance of magnesium alloys sharply decreased after laser surface cladding (LSC) of Al þ Sn, for the galvanic corrosion between Al and Sn. Conversely, the corrosion resistance was improved by laser surface alloying (LSA) of Sn due to the refinement effect and the protection of Mg 2 Sn and SnO 2 in the grain boundary to the a-Mg matrix.

Corrosion resistance and characterization studies of calcium series chemical conversion film via green pretreatment on magnesium alloy

“…Where Y 0 is a proportional factor, j is the imaginary unit (−1 ), ω is the angular frequency and n as the deviation parameter (−1≤ n ≤ 1, which is dependent on the surface morphology). The double-layer capacitance values ( C dl ) can be calculated from the CPE parameter values Y 0 and n using the expression (Zhang et al , 2010; Ghasemi et al , 2008; Wang et al , 2014): …”

Influence of coating thickness on the morphology of TiC particles

“…Wear conditions were a normal load of 49 N, a sliding speed of 200 r min −1 and a sliding time of 20 min. The wear volume could be calculated by Equation (1) after measured the depth and width of wear scars [10]:…”

“…On the basis of service condition, some materials with special performance are coated on the magnesium alloy surface by the laser cladding technology, the wear resistance and corrosion resistance can be effectively improved [1][2][3][4]. The Al-based coatings have a good metallurgical bonding with the magnesium alloy substrates because the aluminium and magnesium can form the limited solid solution [5,6].…”

Al-WC composite coating on AZ91D Mg alloy by low power pulsed laser cladding

“…The cladding powders applied on Mg substrate generally are classified as five types: binary metal powders such as Al-Cu [7], Al-Si [8][9][10], and Al-Sn [11]; ternary metal powders like Ni-Cu-Al [12], Ni-Zr-Al [13], and Ti-Ni-Al [14]; single pure ceramic powders like SiC [15], Al 2 O 3 [16] which are in general processed by plasma-spraying followed by laser cladding; mixture powders used to in-situ synthesize ceramic reinforced particle such as Al-Zr-B 4 C [17], Al-Ti-B 4 C [18]; mixture powders of metal and ceramic particle like Al-Al 2 O 3 [19], Al-SiC [20,21], and Al-Al 2 O 3 [22]. Composite coatings in which ceramic particles with a certain size are added directly may improve hardness and wear resistance and corrosion resistance of the coating.…”