20钢基体表面热浸镀铝＋微弧氧化复合处理研究

摘要

针对大功率柴油发动机排气管的隔热层损伤问题，首先采用热浸镀技术在20钢基体表面制备了铝涂层，然后采用微弧氧化技术对铝涂层进行了氧化处理，形成了复合陶瓷涂层体系，并利用扫描电子显微镜（Scanning E-lectron Microscopy，SEM）、X射线衍射仪（X-Ray Diffraction，XRD）及 DZDR S 导热仪对该涂层体系分别进行了表面形貌与组织结构观察、物相分析和热导率检测。结果表明：从宏观上，涂层表面较平整，无漏镀现象，微观上分布有大量微弧孔，但无微裂纹现象；从剖面来看，复合涂层从表至里分别由氧化铝陶瓷层、铝层和铁铝合金层组成；复合陶瓷层的主要物相组成为 Al、α-Al2 O3、Al86 Fe14和 Fe，其导热率可达20．06 W／（m·℃）。%In view of the serious surface hot-corrosion problem of the exhaust pipe of ship diesel engine, firstly the aluminium coating is made on the surface of 20 steel substrate by the hot dip aluminum technlo-ogy,and then the oxidation processing is conducted by micro-arc oxidation,a multilayer composite ce-ramic coating system is obtained.The morphology,construction,phase analysis and thermal conductivity of the coating are investigated by SEM(Scanning Electron Microscopy),XRD(X-Ray Diffraction)and DZDR S thermal conductivity instrument.The results show that the macro morphology of the coating is smooth and none-plating-leakage.The micro morphology of the coating shows lots of micro-arc holes and no micro-crack;from surface to inner,the composite coating includes Al2 O3 ceramic layer,aluminum layer and Fe-Al alloy layer;the main phase of the coating system is Al,α-Al2O3,Al86Fe14 and Fe,and its thermal conductivity is 20.06 W/(m·℃).