Fabrication of Vanadium–Zirconium Conversion Coatings on 6061 Aluminum Alloy and Performance Modulation by Additives
Year: 2025
Type: article
Abstract: Aluminum alloys used in harsh environments often suffer from inadequate protection due to the limited compactness and stability of existing chromate-free conversion coatings. This study designs and optimizes a corrosion-resistant vanadium-based conversion coating on 6061 aluminum alloy and investigates the influence of additives on its structure and performance. The effects of solution pH (2–4), reaction temperature (35–75 °C), and immersion time (10–30 min) on coating corrosion resistance were examined. The optimal parameters were determined as pH = 3, 55 °C, and 25 min, yielding a compact coating with excellent corrosion resistance (icorr = 0.335 μA·cm−2, Ecorr = −0.596 V, |Z| = 48.7 kΩ·cm2). To further enhance performance, polyvinyl alcohol (PVA), chitosan (CS), and a combination of sodium hexametaphosphate and cerium nitrate (SHMP + Ce(NO3)3) were introduced into the conversion solution. Characterization by SEM, AFM, and contact angle measurements showed that SHMP + Ce(NO3)3 significantly improved coating uniformity and compactness (Rq = 131 nm, Ra = 107 nm), resulting in superior corrosion resistance (icorr = 0.055 μA·cm−2, |Z| = 67.9 kΩ·cm2). The coating exhibited strong adhesion (grade 5B) and no visible corrosion after 72 h of neutral salt spray exposure, demonstrating excellent protective capability. In contrast, PVA produced porous coatings with reduced resistance, while CS provided only limited improvement.
Source: Coatings
Authors: Jiahao Fan, Song Luo, Li Zheng, Zhoumao Song, Xianrui Pen
Institution: Sichuan University of Science and Engineering
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,137
OpenAlex ID: W4416723561