Reoxidation process and corrosion behavior of TA15 alloy by laser ablation
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Reoxidation process and corrosion behavior of TA15 alloy by laser ablation Bo-Wen Liu, Gao-Yang Mi, Chun-Ming Wang*
Received: 10 January 2020 / Revised: 24 March 2020 / Accepted: 26 July 2020 Ó The Nonferrous Metals Society of China and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The thermal oxide layer formed of TA15 alloy has poor corrosion resistance. In this paper, the changes of the elements and components on the surface after laser ablation with different energy densities (E) were researched. The formation process and corrosion behavior of laser-generated oxide layer were clarified. As E increases, the oxygen content decreases from 8.52% to 5.43% and then increases to 11.89%. The surface oxide layer changes from TiO2(R) (i.e., rutile) to Ti2O3 ? TiO2(R) and finally becomes TiO2(R) ? TiO2(A) (i.e., anatase). The TiO2(R) gasification was confirmed by calculating the surface temperature rise. The surface reoxidation process was illustrated by a thermodynamically calculated DGT(i.e., the Gibbs free energy changes with temperature). When E C 17.5 Jcm-2, the oxide layer exhibits an agitated morphology, and oxide falls off at the bottom. As E increases, the corrosion rate decreases first and then increases. With energy density of 8.75 Jcm-2, the surface corrosion rate was 20.43 times slower than that of the untreated sample. The impedance spectrum and equivalent resistance results also prove the best corrosion resistance at 8.75 Jcm-2. The corrosion behavior of the oxide layer is analyzed from the properties of the oxide layer components and the reaction products with the electrolyte. Keywords Laser ablation; TA15 alloy; Reoxidation process; Corrosion behavior; Elemental analysis
B.-W. Liu, G.-Y. Mi, C.-M. Wang* School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China e-mail: [email protected]
1 Introduction Titanium alloy has excellent properties such as high strength, high heat resistance, and low density. However, it is easy to form a thermal oxide layer in hot and humid conditions. Thermal oxide layer not only has poor oxidative resistance [1, 2], and poor corrosion resistance [3, 4], but also affects subsequent manufacturing and processing [5, 6]. Traditional removal methods are chemical treatment and sand blasting. Chemical treatment causes damage to the environment [7]. Treatment agent may also be contaminate materials. Sand blasting damages the substrate severely and easily causes uneven machining surfaces [8]. A high-precision, low-pollution titanium alloy oxide film removal method is urgently needed. The non-contact and pollution-free characteristics of lasers have attracted attention in various fields. Laser ablation technology uses high-energy laser beams to rapidly vaporize pollutants. Micron-level processing accuracy reduces damage to the substrate. In recent years, laser ablation has been used in material coating removal, welding pretreatment, and post-treatment techniques for welding [9–
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