热浸镀与微弧氧化复合处理20钢的表面性能

为提高舰船发动机排气管用20钢基材耐腐蚀等表面性能,采用热浸镀铝与微弧氧化技术复合处理形成铝-陶瓷复合层,采用显微硬度计、扫描电镜、多功能材料表面性能测试仪、电化学工作站等表征复合层显微硬度、耐磨、耐腐蚀和抗热震等表面性能。结果表明:复合层至基体间结构层硬度分布呈硬-软-硬-软的间断区域性分布特点;铝-陶瓷复合层的耐磨性优于铝镀层和20钢基体;与20钢基体相比,铝镀层和复合陶瓷层的全浸泡腐蚀失重值下降,腐蚀反应极化电阻增加,腐蚀电压增大,腐蚀电流密度减小,尤其是复合陶瓷层的耐腐蚀性显著提高,耐盐雾能力达1 000 h;陶瓷复合层在600℃下热震次数可达130次,层间界面结合紧密。

Surface Performance of 20 Steel Prepared by Methods of Hot Dip Aluminum and Micro-Arc Oxidation

In order to improve the surface performances containing corrosion resistance of 20 steel substrate that applied to exhaust pipes for marine engines,a composite layer was obtained on the surface of 20 steel plate by combined methods of hot dip aluminum and micro-arc oxidation. The micro-hardness,morphology,wear-resistance,anti-corrosion and hot-shocking performance of the composite layer were investigated by micro-hardness instrument,scanning electron microscope,surface performance instrument,electrochemical workstation and etc. Results showed that the micro-hardness distribution from the composite layer to the substrate appeared the characteristics of hard-soft-hard-soft discontinuous regions. Moreover,the wear-resistance of Al-ceramic composite layer was higher than that of Al layer and the 20 steel substrate. In comparison of 20 steel substrate,Al layer and ceramic layer possessed lower weight loss of total immersion corrosion,larger corrosion polarization resistance,bigger corrosion potential and smaller corrosion current density. In particular,the corrosion resistance of composite ceramic layer was significantly improved,and it could endure salt corrosion for 1 000 h. Besides,the effective hot-shocking times of the coating was130 at 600 ℃,presenting excellent interlayer binding.