Wang Jintao, Zhang Xiaoshun, Chen Mengfan, Zhang Xihao, Zhang Zhongliang, Liu Jianguo
School of Forensic Science, Criminal Investigation Police University of China, Shenyang 116049, China.
Key Laboratory of Impression Evidence Examination and Identification Technology, Ministry of Public Security, Shenyang 110035, China.
Micromachines (Basel). 2025 May 15;16(5):578. doi: 10.3390/mi16050578.
Vehicle identification number (VIN) reappearance technology is an important means of vehicle traceability in various criminal cases. However, with the advancement of metallurgical techniques, the corrosion resistance of metal becomes stronger, and the traditional chemical etching reappearance method gradually fails. In order to break through the dilemma of traditional methods, this study establishes an electrochemical corrosion system by introducing the corrosion inhibitor hexamethylenetetramine (HMTA) to precisely regulate the electrochemical dissolution kinetics. Material characterization and electrochemical measurements demonstrated that the selective adsorption of HMTA significantly enhances the potential difference between plastically deformed regions and the normal metal substrate (ΔE = 6 mV). By effectively suppressing the corrosion rate in non-target areas, HMTA promotes selective anodic oxidation reactions in the vehicle identification number character regions due to their distinct microstructural characteristics, thereby substantially improving the contrast of the reappeared VIN markings. Density functional theory calculations and molecular dynamics simulations further reveal the formation of a dense adsorption layer, which is a key factor in improving the reproducibility of the results. The experimental results demonstrate that under conditions of 6 V applied voltage, with 0.5 M hydrochloric acid and 0.02-0.03 M HMTA in the electrolyte, efficient VIN reappearance could be achieved within 3-4 min on filed-down surfaces.
车辆识别号码（VIN）重现技术是各类刑事案件中车辆溯源的重要手段。然而，随着冶金技术的进步，金属的耐腐蚀性增强，传统的化学蚀刻重现方法逐渐失效。为突破传统方法的困境，本研究通过引入缓蚀剂六亚甲基四胺（HMTA）建立了电化学腐蚀体系，以精确调控电化学溶解动力学。材料表征和电化学测量表明，HMTA的选择性吸附显著提高了塑性变形区域与正常金属基体之间的电位差（ΔE = 6 mV）。通过有效抑制非目标区域的腐蚀速率，HMTA由于车辆识别号码字符区域独特的微观结构特征，促进了这些区域的选择性阳极氧化反应，从而大幅提高了重现的VIN标记的对比度。密度泛函理论计算和分子动力学模拟进一步揭示了致密吸附层的形成，这是提高结果重现性的关键因素。实验结果表明，在施加6 V电压的条件下，电解液中含有0.5 M盐酸和0.02 - 0.03 M HMTA时，在打磨过的表面上3 - 4分钟内即可实现高效的VIN重现。
