Modified potassium titanate whiskers for preparation of enhanced corrosion-resistant phosphating conversion coatings with high NIR reflectivity on mild steel

• Published in: Journal of alloys and compounds 2023-09, Vol.955, p.170247, Article 170247
• Main Authors: Wang, Weishan, Tian, Yuqin, Shen, Huifang, Zhang, Xinya
• Format: Article
• Language: English
• Subjects: Cool coatings; Corrosion resistant; Phosphating conversion coatings; Potassium titanate whiskers; Super-hydrophobic
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2023.170247

In this paper, Potassium titanate whiskers (PTW), a kind of high NIR reflectional material, were modified with stearic acid (SA) and used as a green accelerator in phosphating bath to build super-hydrophobic phosphating conversion coatings (PCCs) with enhanced corrosion resistance and high NIR reflectivity on mild steel in one-step at low temperature. The scanning electron microscopes (SEM), water contact angle (WCA), X-ray diffraction (XRD), potentiodynamic polarization, copper sulfate titration, electrochemical impedance spectroscopy (EIS), long-term immersion test, NIR reflectivity, linear abrasion experiment as well as tape peeling experiment were investigated to explore the performance of PCCs. The PCCs with the optimal 0.8 g/L concentration of SA-PTW possesses the densest structure, the largest WCA of 153° and the highest NIR reflectivity of 48 %. The potentiodynamic polarization results show that the 0.8-SA-PTW occupies the lowest corrosion rate (7.531 ×10−4 mpy), and remains minimal (3.56 ×10−3 mpy) after soaking in 3.5 wt % NaCl solutions for 20 days, resulting in enhanced long-term corrosion protection of mild steel. These special properties of PCCs effectively prevent the invasion of corrosive medium and the heat accumulation which would have great potential applications in anti-corrosion “cool coatings” for exterior corrosion protection of body and hull. [Display omitted] •SA-PTW was introduced as green accelerator for preparing PCCs at low temperature.•The PCCs decrease the corrosion rate from 1.045 mpy to 7.531×10-4 mpy, and possess excellent long-term corrosion resistance.•SA-PTW endows the coating super-hydrophobicity (153 °) and NIR reflection properties (48%).•The PCCs can be used for energy-efficient and anti-corrosion “cool coatings”.