Composited MAO coating with SiO2 particles on TA2 alloy by laser treatment

• Published in: Surface & coatings technology Vol. 472; p. 129966
• Main Authors: Li, Weizhou, Chen, Quanzhi, Shen, Deli, Yang, Ruixia, Zhang, Xiuhai
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.11.2023
• Subjects: Composite coating; Laser treatment; Micro-arc oxidation; SiO2 particles; TA2 alloy; SiO2 particles; Composite coating; TA2 alloy; Laser treatment; Micro-arc oxidation
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2023.129966

In order to decrease defects and improve protective performance, micro-arc oxidation (MAO) coating was modified by adding SiO2 particles to form a composite coating on TA2 alloy via laser treatment. The microstructural morphology, phase structure, cohesive strength and corrosion resistance of the composite coatings were investigated and analyzed by using SEM, XRD, thermal cycle, and electrochemical testing, respectively. The results showed that SiO2 particles were firstly adsorbed onto the MAO surface with the aid of ultrasonic treatment and then sealed micro-pores of the MAO coating after laser treatment. The composite coating mainly consisted of R-TiO2, A-TiO2 and SiO2 phases and exhibited a dense multilayer structure with a rich Si element in the outer layer. After subjecting the coatings to 300 thermal cycles, clacking or marked spalling zones could not be observed in the composite coating; nevertheless, an obvious destruction appeared in the single MAO coating without SiO2 particles. The corrosion potential (Ecorr) and pitting potentials (Epit) of the composite coating were −0.303 V and 1.765 V compared to that of −0.682 V and 1.401 V for the single MAO coating. Additionally, the corrosion rate decreased to 1.40 × 10−4 A·cm−2 with the highest resistance (76,788.67 Ω·cm2) from2.19 × 10−4 A·cm−2, indicating a stronger corrosion resistance in the composite coating. The results of simulation from Comsol Multiphysics demonstrated that a laser power as 80 W was appropriate for melting SiO2 particles into the MAO coating to form a dense and cohesive composite coating. •SiO2 particles were incorporated into the MAO coating by laser treatment.•Composite coating with SiO2 exhibited stronger resistance to thermal shock and corrosion.•Laser power was important to melt SiO2 and not influence the coating/substrate interface.