【作者】 李俊杰；

【导师】 翟文正；

【作者基本信息】 华中科技大学 ， 机械（专业学位）， 2022， 硕士

【摘要】 镍铝青铜（NAB）由于具有优异的机械性能和耐腐蚀性能被广泛用于深海远洋装备。传统的镍铝青铜制造工艺在制造复杂的零部件时常常出现微观组织不均匀,这将导致机械性能和耐腐蚀性能的降低。金属增材制造作为一种新的制造工艺,可以解决微观组织分布不均匀的问题。本文重点研究了三种不同初始粒径（小粒径45-63μm、中粒径63-75μm、大粒径75-105μm）的增材制造镍铝青铜微观组织演变以及腐蚀形貌,通过电化学实验对比了其与常规铸造镍铝青铜在海水环境下的静态腐蚀特性。此外,为了进一步提高增材制造镍铝青铜耐蚀性能,采用激光加工方法在增材制造镍铝青铜表面构筑微观超疏水结构,并分析其表面形貌、润湿性和耐静态腐蚀性。主要研究成果如下:（1）增材制造镍铝青铜是由α基体、B2型的NiAl和DO3型的Fe₃Al沉淀相组成,与传统铸造镍铝青铜（As-cast-NAB）相比,增材制造镍铝青铜（EBSM-NAB）第二相分布均匀性得到很大改善,在200μm尺度内分布均匀。（2）与As-cast-NAB相比,EBSM-NAB选相腐蚀得到明显改善。电化学实验结果表明,腐蚀7 d后,中粒径NAB的极化电阻为29925Ω·cm²,而As-cast-NAB合金的极化电阻为22114Ω·cm²,中粒径的极化电阻增加了约1.35倍。这主要归因于EBSM-NAB第二相分布的均匀性获得很大程度的改善。（3）为进一步提高EBSM-NAB表面耐腐蚀特性,采用激光处理获得表面微结构,当激光功率为50 W时,加工后的EBSM-NAB表现为超疏水特性,静态接触角为153°,滚动角为5°。激光加工后镍铝青铜虽然耐腐蚀性随着浸泡时间的增长而降低,但腐蚀7 d后其极化电阻仍可以达到176753Ω·cm²,远远大于极化电阻处于增长状态的中粒径NAB合金（极化电阻为29925Ω·cm²）。更多还原

【Abstract】 Nickel-aluminum bronze（NAB）is widely used in deep-sea ocean-going equipment due to its excellent mechanical properties and corrosion resistance.Traditional nickel-aluminum bronze manufacturing processes often produce uneven microstructures when manufacturing complex parts,which will result in reduced mechanical properties and corrosion resistance.As a new manufacturing process,metal additive manufacturing can solve the problem of uneven distribution of microstructure.This thesis focuses on the microstructure evolution and corrosion morphology of additively manufactured nickel-aluminum bronze with three different initial particle sizes（small particle size 45-63μm,medium particle size 63-75μm,large particle size 75-105μm）.Electrochemical experiments were conducted to compare its static corrosion characteristics with conventional cast nickel-aluminum bronze in seawater environment.In addition,in order to further improve the corrosion resistance of additively manufactured nickel aluminum bronze,the microscopic superhydrophobic structure was constructed on the surface of additively manufactured nickel-aluminum bronze by laser processing,and its surface morphology,wettability and static corrosion resistance were analyzed.The main research results are as follows:（1）Additively manufactured nickel-aluminum bronze is composed ofαmatrix,B2-type NiAl and DO3-type Fe₃Al precipitation phase.The distribution uniformity of the second phase in the additively manufactured nickel-aluminum bronze（EBSM-NAB）is greatly improved compared with the conventional cast nickel-aluminum bronze（As-cast-NAB）,and the distribution is uniform in the 200μm scale.（2）Compared with As-cast-NAB,the phase selective corrosion of EBSM-NAB is significantly improved.The electrochemical experiment results show that the polarization resistance of the medium-sized NAB is 29925Ω·cm² after corrosion for 7 days,while the polarization resistance of the As-cast-NAB alloy is 22114Ω·cm²,The polarization resistance of the medium particle size is increased by a factor of about 1.35,which is mainly attributed to the uniformity of the second phase distribution in EBSM-NAB.（3）In order to further improve the corrosion resistance of EBSM-NAB,laser processing was used to obtain the surface microstructure.When the laser power is 50 W,The laser processed EBSM-NAB shows super-hydrophobicity.Its static contact angle is 153°and the rolling angle is 5°.Although the corrosion resistance of Ni-Al bronze after laser processing decreases with the increase of immersion time,its polarization resistance can still reach176753Ω·cm² after 7 days of corrosion,which is much larger than that of the medium-sized NAB whose polarization resistance is increasing（polarization resistance is 29925Ω·cm²）.更多还原