Effects of heating time on corrosion behavior and surface conductivity of Ti-Al coated Ti-6Al-4V

Titanium alloys are potential candidates with low density, high strength and excellent corrosion resistance to meet the demand of bipolar plate of fuel cell for vehicles. Nevertheless, the shortcomings of low conductivity and corrosion resistance in acid solutions need to be addressed. Herein, a Ti - Al coating with both high interfacial conductivity and corrosion resistance is fabricated on the surface of Ti-6Al-4V (TC4), relying on a facile in -situ generation of pack cementation method. The effects of heating time on the morphology, composition, thickness, and wettability of the Ti - Al coating were investigated. The corrosion resistance and conductivity were also studied, and the corresponding mechanisms were discussed in detail. The results indicated that the heating time significantly affects the morphology, composition, thickness and wettability, which distinctly affects the corrosion resistance and conductivity of the coated samples. All coated samples exhibit a higher hydrophobicity than TC4 before and after the potentiostatic polarization test. The corrosion resistance of the coated samples firstly improved and then decreased with increasing heating time. At a heating time of 14 h, the coated sample presents the lowest corrosion current density (1.45 x 10 -7 A/cm 2 ) and interfacial contact resistance value (7.5 Omega cm 2 ) after the potentiostatic polarization test.