镁合金表面再制造AlCoTi非晶涂层组织及力学性能研究

采用高速电弧喷涂技术在AZ91镁合金表面制备了高非晶含量AlCoTi涂层，研究了涂层显微组织、力学性能、摩擦磨损及电化学腐蚀性能。结果表明，涂层呈典型的层状结构，其结构紧凑，与镁合金基体结合良好，孔隙率约为1.63%。涂层的组织主要由非晶相、纳米结构的α-Al和Al3Ti相组成。相比于AZ91镁合金，AlCoTi非晶涂层具有更高的显微硬度和耐磨性能：涂层的显微硬度约为511.3Hv0.1，远高于AZ91镁合金(62Hv0.1)；在相同的磨损条件下，非晶涂层相对耐磨性约为晶体结构AZ91镁合金的3.9倍，其主要磨损机制为脆性剥落。在0.6 mol/L NaCl溶液中，非晶涂层自腐蚀电位、自腐蚀电流密度和电荷转移电阻分别为-0.696V、0.741 8μA/cm²和33 660?·cm²，明显优于AZ91镁合金的-1.392V、769.3μA/cm²和1 914?·cm²。通过对镁合金表面不同防护涂层的电化学腐蚀性能和显微硬度比较分析，本研究为镁合金提供一种低成本、高性能的涂层材料及再制造关键技术。

Microstructure and Mechanical Properties of the AlCoTi Amorphous Coating for Magnesium Alloy Remanufacturing

The AlCoTi amorphous coating was fabricated onto AZ91 magnesium alloy substrate by using high velocity arc spraying process. The microstructure, mechanical properties, wear and electrochemical corrosion behaviours of the coatings were studied. The coating shows a typical laminar morphology with compact structure and a good combination with the substrate. The porosity of the coating is about 1.63%. The microstructure of the coating consists of amorphous phase, α-Al and Al₃Ti nanocrystalline phases. The coating displays higher microhardness and better excellent wear resistance than AZ91 alloy. The microhardness of the coating is about 511.3 HV_0.1, which is much higher than the AZ91 magnesium alloy (62 HV_0.1). The relative wear resistance of the AlCoTi amorphous coating is about 3.9 times that of AZ91 magnesium alloy under the same wear circumstances. The main failure mechanism of the coating is brittle spalling. In 0.6 mol/L NaCl solution, the AlCoTi amorphous coating displays excellent corrosion resistance. The corrosion potential, current density and charge transfer resistance of the coating are －0.696 V, 0.741 8 μA/cm² and 33 660 Ω·cm², respectively, while that of the magnesium alloy is －1.392 V, 769.3 μA/cm² and 1 914 Ω·cm², respectively. This study provides a low-cost, high-quality and efficient remanufacturing protective coating for magnesium alloy by analyzing the electrochemical corrosion properties and microhardness compared with other coatings.