【作者】 张立伍；

【导师】 陶杰；

【作者基本信息】 南京航空航天大学 ， 材料加工工程， 2010， 硕士

【摘要】 为提高钛管件表面硬度,改善其耐磨损、耐腐蚀性能,需要对其表面进行处理。本文采用一种新工艺,制备了带有氧化铝陶瓷涂层的钛基复合管件。首先用爆炸焊接工艺制备了钛/铝复合管材,利用扫描电子显微镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)分析了复合管界面的形貌、元素分布及相组成,结果表明钛/铝复合管界面过渡层由钛-铝固溶体组成,实现了冶金结合,界面无微观裂纹存在。采用压剪试验、径向压扁试验和轴向压缩试验研究了界面结合性能。运用Marc有限元软件对钛/铝复合三通管件液压胀形和弯头推弯成形进行了数值分析,研究表明复合三通管件胀形所需的最小结合强度为5MPa。当摩擦系数小于0.1,内压力为100MPa,左右冲头的进给距离为25mm时,成形效果较好;复合弯头推弯所需最小结合强度为50MPa,摩擦系数应小于0.15。根据模拟结果对钛/铝复合管件进行了液压胀形和推弯成形试验,制备的钛/铝复合管件尺寸精度较高,双金属的界面结合良好。通过微弧氧化工艺对经过化学铣切处理的钛/铝复合三通和弯头管件进行了陶瓷化处理,分别采用划痕仪、电化学工作站及球盘式摩擦磨损试验机,对氧化铝陶瓷涂层的力学性能、耐腐蚀性能和摩擦学性能进行了表征,结果表明陶瓷涂层与基体结合力达55N,涂层腐蚀电流比钛基体降低5个数量级,摩擦系数比钛基体降低8倍。综合分析表明,运用有限元方法对钛基复合管件冷成形进行模拟,能较好地指导实际冷成形试验。通过新工艺所制备的带有陶瓷涂层的钛基复合管件能够显著提高钛基体耐磨损及耐腐蚀性能。更多还原

【Abstract】 Titanium pipe-fittings with ceramic coatings were prepared using a new composite process in this work to improve their surface hardness, corrosion resistance and wear properties..Firstly, the Ti/Al composite tube blanks were produced by explosive welding. The microstructure, element distribution and phase composition around the interface of the composite tubes were characterized respectively with the aid of scanning electron microscope （SEM）, energy dispersion X-ray spectrum （EDS） and X-ray diffraction （XRD）.The results showed that the metallurgical bonding occurred without any microcracks at the interface between Al and Ti matrix, and the microstructure around the interface was Ti-Al solid solution. The bonding strength of composite tubes was investigated individually by means of compression shear test, flattening test and upset test.Then, the Marc software was used to simulate the hydroforming process of T-shapes and push bending process of elbows. It was found that more than 5MPa interface bonding strength and less than 0.1 friction coefficient were needed with internal pressure 100MPa and feed distance 25mm in the hydroforming process. For the push bending process, the critical interface bonding strength was 50MPa, friction coefficient was less than 0.15. Ti/Al composite T-shapes and elbows with high size accuracy and good bonding strength were manufactured successfully according to the simulation results.The Al₂O₃ coatings were prepared by micro-arc oxidation. The adhesion strength, corrosion resistance and tribological behavior of Al2O3 coatings were investigated individually through scratch adhesion test, electrochemistry work station and ball-on-disc tribological test. The results reveal that the Al2O3 coatings have the bonding force of over 55N. The corrosion current of the Al2O3 coatings decreases dramatically by 5 magnitudes owing to their compact structure. Furthermore, the prepared coatings possess good wear resistance with friction coefficient 8 times lower than that of the titanium substrate.The above analysis indicates that the numerical simulation can guide the practical forming of Ti-based composite pipe-fittings effectively. Ti-based composite pipe-fittings with Al2O3 coatings prepared by a new composite process can improve their wear resistance and corrosion properties, significantly.更多还原